Recognition and revision of the Phelister blairi group (Histeridae, Histerinae, Exosternini)

Abstract Forty-nine new species of Neotropical Exosternini are described in this work, representing the newly recognized Phelister blairi species group, within the large, heterogeneous taxon Phelister. Eight previously described species are also assigned to this group. Relationships within are indicated with several informal subgroups: P. blairi subgroup: (P. blairi Hinton, 1935, P. erwinisp. nov., P. fimbriatussp. nov., P. stellanssp. nov., P. sparsussp. nov., P. pretiosussp. nov., P. trigonisternus Marseul, 1889, P. globosussp. nov., P. serratussp. nov., P. geminussp. nov., P. paranasp. nov., P. asperatussp. nov., P. uniformissp. nov., P. miscellussp. nov., P. inbiosp. nov., P. sculpturatus Schmidt, 1893, P. tunkisp. nov., P. praedatoris Reichensperger, 1939, P. ifficussp. nov., P. genierisp. nov., P. marginatussp. nov., P. vazdemelloisp. nov., P. dilatatussp. nov., P. spectabilissp. nov., P. pervagatussp. nov.); P. amazoniae subgroup: (P. morbidussp. nov., P. annulatussp. nov., P. sphaericussp. nov., P. geijskesi Kanaar, 1997, P. fraternussp. nov., P. conjunctussp. nov., P. chabooaesp. nov., P. striatinotum Wenzel & Dybas, 1941, P. notandus Schmidt, 1893, P. amazoniae (Lewis, 1898) comb. nov., P. arcuatussp. nov.); P. gregarius subgroup: (P. gregariussp. nov., P. praecisussp. nov., P. rudissp. nov., P. incongruenssp. nov., P. congruenssp. nov., P. praesignissp. nov.); P. umens subgroup: (P. umenssp. nov., P. almeidaesp. nov., P. chicomendesisp. nov., P. microdenssp. nov., P. matatlanticasp. nov.); P. curvipes subgroup: (P. curvipessp. nov., P. vilavelhasp. nov.); P. rio subgroup: (P. riosp. nov., P. semotussp. nov., P. uncinatussp. nov., P. inscriptussp. nov.); incertae sedis – unplaced to subgroup: (P. incertussp. nov., P. okeefeisp. nov., P. blairoidessp. nov., P. piranasp. nov.). Lectotypes are designated for the following species: P. trigonisternus Marseul, P. sculpturatus Schmidt, P. praedatoris Reichensperger, P. notandus Schmidt, and Discoscelis amazoniae Lewis. Preliminary phylogenetic analyses of the broader Neotropical Exosternini do not support the monophyly of the P. blairi group, nor of all of these subgroups, but the majority do fall within one large clade (which is potentially paraphyletic with respect to some other Neotropical exosternine genera). More work on the phylogeny and taxonomy of this diverse fauna is needed.


Introduction
The Neotropical Exosternini represent one of the largest radiations of Histeridae, with more than 650 species (Caterino and Tishechkin, unpub. data). To date fewer than half of these have been described (298 spp.), but even this represents a three-fold increase over the past decade. As relationships and taxonomic limits have slowly improved, we have carved off and revised a number of subgroups/genera (Caterino et al. 2012(Caterino et al. , 2013Caterino and Tishechkin 2013a, b, 2014, 2016, 2019. However, the fauna remains a complicated one, containing many small, similar-looking species with relatively few distinguishing features. Attempts to resolve these relationships in order to delineate more meaningful taxa have met with mixed success (Caterino and Tishechkin 2015), and we have largely taken a pragmatic approach, under the presumption that increasing knowledge of the species level diversity across the tribe will lead to further improvements in our understanding of the higher level relationships. We continue that approach here, expanding the scope of the already large taxon Phelister.
In the present paper, we circumscribe a new subgroup of Phelister, the P. blairi group, redescribing several previously described species that we assign here, describe a large number of species, and perform a phylogenetic assessment of where they fit in among the other neotropical Exosternini. The P. blairi group contains 57 species, 49 of them being described here as new. We allocate most of these to six informal subgroups, leaving four unplaced to subgroup. Informally, the authors have long referred to these as 'the scutellar impression group', and most (not all) of the included species exhibit a distinct prescutellar impression. More formally, we have previously referred to these as 'Phelister blairi group', though without explicitly assigning species to it (Caterino and Tishechkin 2013b). Most (7 out of 8) of the previously described species here have been assigned to Phelister. However, the sole exception points out the primary challenge with this group: this is Reninus amazoniae (Lewis), clearly a relative of Phelister blairi and other more generalized species, but until now assigned to a genus of Haeteriinae. In fact, many Neotropical Exosternini exhibit highly modified morphologies, attributable in most to inquilinism with social insects, mainly ants. The Phelister blairi group encompasses one or more such transitions into inquilinous habits, and offers an interesting array of morphological characters accompanying the transition.
In our previous phylogenetic analysis of Neotropical Exosternini (Caterino and Tishechkin 2015), most of the species included here fell out within a large clade sister to much of Phelister. However, there were a number of exceptions to their exclusivity. Several species that we contend should be closely related fell elsewhere among the diverse Phelister species. In other cases, some falling outside the 'blairi group' would support preliminary hypotheses that the similarities shared (a prescutellar impression, mainly) were homoplasious. On the other hand, the core blairi group clade also appears to be paraphyletic with respect to several other taxa, especially if we include Phelister striatinotum in our blairi group concept, which we have. The few 'typical Phelister' inclusions are all species that have large amounts of missing data (male genitalia and DNA, especially), and for now cannot be adequately evaluated. However, the inclusion of most of the genera that we recently described (Pyxister, Crenulister, Conocassis, etc.;Caterino and Tishechkin 2014) as well as the very large genus Operclipygus poses significant difficulties. To address these, we present some new analyses, based on a reduced taxon set (allowing more thorough analysis of more contentious relationships), and discuss some slightly refined perspectives on relationships below.

Materials and methods
The morphological terminology used is that defined by Wenzel and Dybas (1941), supplemented by Helava et al. (1985), Ôhara (1994), and Caterino and Tishechkin (2013b). Following histerid conventions, total body length is measured from the anterior margin of the pronotum to the posterior margin of the elytra (to exclude preservation variability in head and pygidial extension), while width is taken at the widest point, generally near the elytral humeri. Conventional imaging was done using Leica's Photomontage imaging system and Visionary Digital's 'Passport' portable imaging system, which incorporates a Canon 7D with MP-E 65 mm 1-5 × macro zoom lens. Images obtained with the Passport system were stacked using Helicon Focus software. SEM imaging was done on a Zeiss EVO 40 scope, and the specimens were sputtercoated with gold. We have studied and imaged primary types of all species; images of these type specimens beyond those presented in this paper are available from the authors. Data quoted verbatim from labels are surrounded by double quotes ("_") with distinct labels separated by slashes (/). Non-verbatim data (paratypes and 'other material') are summarized in a standard format. GPS coordinates have been inferred for most localities and/or standardized to decimal degrees. Dates outside of verbatim records are presented as MM/DD/YY.

Phylogeny
We analyzed a subset of taxa from the 750+ taxon data set of Caterino and Tishechkin (2015) to attempt to better resolve species hypothesized to belong to the Phelister blairi group. This pruned data set included only small numbers of exemplars for those groups previously strongly supported as monophyletic. Specifically, it includes only three species of Baconia Lewis, two species of Hypobletus Schmidt, and one of Megalocraerus Lewis. We included twelve species of Operclipygus Marseul, given potentially close relationships to the blairi group, and most species of recently described genera (Caterino and Tishechkin 2014) with potential relationships to the blairi group. We reduced the number of outgroups to 12 (from 61), representing non-neotropical Exosternini, other tribes of Histerinae, and Haeteriinae. Finally, we added five newly discovered or recognized species within our concept of the blairi group (and removed a few others now considered synonyms of other species). This revised data set included a total of 235 taxa, including most described and undescribed Phelister and Pseudister spp., as well as many other undescribed species of uncertain placement. The included data for all partitions are identical to those included in our 2014 analysis. This included 259 morphological characters (141 external morphol-ogy, 87 of male genitalic morphology, and 31 of female genitalic morphology), and approximately 1/4 were represented by some molecular data, including some combination of 18S, 28S, and cytochrome oxidase I. Molecular data were sparse for blairi group taxa, as most of these have been collected only through flight interception trapping. Suppl. material 1: Table S1 details what species were included and what partitions were available for them. We did not realign the length variable portions for this reduced dataset, maintaining homology assessments from the preceding analysis. For original alignment parameters see Caterino and Tishechkin (2015). This reduced data set is available as an online supplement (Suppl. material 2). Tree searching was performed in PAUP* (v. 4.0a164;Swofford 2002) under the maximum parsimony criterion, running 1000 random sequence addition replicates, saving no more than 2000 trees for each replicate.

Phylogeny
This analysis yielded 131648 trees of 13048 steps (CI: 0.1752; RI: 0.4006). The majority rule consensus of these ( Fig. 1) is remarkably well resolved, with high consistency of the vast majority of branches. However, the consistency of the topology with the current taxonomy of Neotropical Exosternini is very low -few genera represented by multiple species are monophyletic. With respect to the possible monophyly of the P. blairi group, which we establish here, monophyly is also not supported. The species that we treat here as the blairi group (names in red in Fig. 1) fall out in 10 places in the tree. Still, the majority (39 spp.) do fall out together, together constituting most of a clade, the only exceptions being a few small genera which have been named as distinct (including Crenulister Caterino & Tishechkin, [2014], to which one of the species we describe here might possibly be related). This large lineage includes most members of the blairi, gregarius, and amazoniae subgroups with the blairi subgroup appearing potentially paraphyletic with respect to the others. The amazoniae subgroup species that are not resolved within this lineage (P. geijskesi and P. striatinotum) are indeed species that exhibit some inconsistent characters. Three subgroups fall entirely outside of this group. Two of these, the curvipes and umens subgroups do appear monophyletic, though far from each other and the rest of the blairi group. The umens subgroup is resolved as the sister of the P. haemorrhous group, which we recently revised (Caterino & Tishechkin, 2019). The rio subgroup falls out in three separate places on the tree, suggesting that the characters those species share are mostly plesiomorphies or convergences. Overall, despite the obvious problems this phylogenetic hypothesis poses for an ideally cladistic nomenclature, this tree does offer improved perspective on possible relationships across Phelister and helps point out areas in which further characters are needed. As we continue to accumulate DNA-grade specimens of these taxa, we look forward to continued improvement in understanding their relationships.  Selected members of all Neotropical Exosternini higher taxa are included. Those we assign to the Phelister blairi group have their names in bold red font. The subgroups that we assign them to are indicated by colored names at the right (red = rio subgroup, green = blairi subgroup, dark blue = amazoniae subgroup, light blue = curvipes subgroup, gold = umens subgroup, violet = gregarius subgroup). Numbers above branches represent majority rule consensus indices.

Diagnosis of the Phelister blairi group
Prescutellar impression ( Fig. 2A-C, E, F) as large or larger than the scutellum, posteriorly confluent with the pronotal margin; frons and epistoma (Fig. 2D) fairly strongly depressed, epistoma sometimes ridged around the margin of this depression; frontal stria almost always present, often interrupted medially or at sides or both; distal margin of labrum emarginate, weakly transversely ridged at middle, sometimes subcarinate; anterior arch of mesometaventral stria reaching middle of mesoventrite or beyond, usually angulate at middle, sometimes arched; lateral submarginal pronotal stria, if present, close to margin, the marginal bead frequently raised between the stria and the edge; median pronotal gland openings ( Fig. 2A-C, E, F; sensu Caterino and Tishechkin 2013b) conspicuous, usually annulate (with a fine stria encircling opening), located on posterior 1/2 of disk in most species; anterior marginal pronotal stria crenulate, usually entire and slightly separated from margin behind head, occasionally interrupted behind eyes and recurved posterad (as in P. blairi and a few others).

Phelister blairi subgroup
This diverse subgroup, comprising 25 species, is defined primarily by genitalic characters, which we list below. There are also some external characters that are frequent if not ubiquitous across the group.
Distribution. This species is most commonly found in northeastern South America, including Pará, Brazil, French Guiana, and Suriname. We have also seen specimens from Peru, but surprisingly not Ecuador.
Remarks. Among the species treated here, P. blairi is best recognized by its small body size, median pronotal gland openings located close to anterior pronotal margin (Fig. 3A), broken anterior marginal pronotal stria, and posteriorly obsolete lateral submarginal pronotal stria. It also has a relatively small area (shortened) enclosed by its prosternal keel striae. Phelister blairoides (#56, below) has similarly anterior pronotal gland openings, but has the lateral submarginal pronotal stria complete, and has the outer subhumeral elytral stria present basally as well as apically (though interrupted at middle). Phelister blairoides is also ~ 2 × as large. Although both these species are widespread and somewhat variable across their ranges, these differences are consistent. This species is also very similar to the following, P. erwini, differing principally by the more anteriorly located pronotal gland openings.

Phelister erwini
Etymology. We dedicate this species to the renowned coleopterist, Dr. Terry Erwin, who unfortunately passed away early in 2020. His groundbreaking surveys of neotropical beetles, outstanding contributions to ground beetle systematics, and important contributions to the cause of insect biodiversity conservation have been a great inspiration to us, and many, many others.
Remarks. This species shows strong similarity to P. blairi, above; their almost completely non-overlapping distributions suggest that the two are sister taxa (and they are resolved as such in our analyses). The pronotal gland openings in P. erwini are nearly always ~ 1/3 removed from the anterior pronotal margin, whereas those of P. blairi are much closer to the anterior margin (see Fig. 3C and 3A, respectively). The two consistently differ near P. blairi's type locality (Pará, Brazil), as well at another point of sympatry (southeastern Peru), but some variation in gland opening location and sculpturing (pronotal and pygidial) make the two difficult to distinguish throughout their ranges and in all specimens.
A number of specimens of P. erwini have been collected in loose association with neotropical army ants (Eciton spp.), suggesting some degree of myrmecophily. However, the vast majority of specimens of this abundant species have been collected with flight interception traps, so other possible associations cannot be assessed.
Etymology. We name this species for the distinctive marginal fringe on the eighth sternite of the male genitalia.
Remarks. While this species shares a lot of its characters with various others in this group, the combination of having its outer subhumeral stria usually interrupted at middle, having 'normal' (not scalloped) protibiae, and having the lateral thirds of the pronotal disk quite distinctly more strongly punctate than the middle third ( Fig. 3E) is unique. It is particularly similar to the following species (P. stellans), but it differs from that one in having the arch of 4 th dorsal stria a little narrower, and the 5 th and sutural striae a little shorter. These seemingly insubstantial differences are backed up by a remarkable difference in the male 8 th sternite (Fig. 6A), which has a long apical fringe; the 8 th sternite of P. stellans has at most a few setae at the outer corners. We have restricted the type series of both species to males where identity could be confirmed by genitalia.
Specimens of this species have only been collected using flight interception traps. Distribution. This species is known from the Guianas, as well as Amazonian Brazil, Peru, and Ecuador.  Diagnostic description. Length: 1.85-2.09 mm (avg. 1.95 mm); width: 1.65-1.93 mm (avg. 1.73 mm). This species is very similar and closely related to the preceding, differing principally in the following characters: ground punctation of dorsum slightly coarser; secondary punctures of lateral portion of pronotum gradually increasing in size and density laterad; lateral submarginal pronotal stria usually not reaching anterior corner, abbreviated at front; outer subhumeral stria complete, not interrupted at middle. Male: S8 with only a couple setae at apical corner; basal piece ~ 1/3 length of tegmen; tegmen with sides weakly rounded, slightly wider toward base, more or less flat, with basal 'notch' in lateral view, apices subacute, weak medioventral process present in basal 1/3; median lobe ~ 1/2 tegmen length, basal apodemes thin.
Etymology. The name of this species means starry, referring to the array of pronotal punctures.
Remarks. This species, like the preceding one, has only been collected through the use of flight interception traps.
Distribution. This species is known from Amazonian Ecuador, Peru, and Brazil, as well as French Guiana. Diagnostic description. Length: 1.85-2.01 mm (avg. 1.95 mm); width: 1.65-1.93 mm (avg. 1.73 mm). Body somewhat narrowly elongate oval, convex, dark rufescent, with ground punctation very fine and inconspicuous; frons and epistoma narrow, depressed along midline, sparsely punctate; supraorbital stria present, narrowly separated from sides of frontal; frontal stria complete, sinuate through frontal depression; epistoma weakly raised along sides and front; labrum narrow, apically emarginate; mandibles lacking basal teeth; antennal club elongate with elongate median setose patch and two smaller basal setose patches on dorsal surface; prescutellar impression broadly oval, ~ twice as wide as scutellum; pronotal disk with sparse secondary punctures close to sides; median pronotal gland openings distinctly annulate, 3/4 behind anterior margin; marginal pronotal stria complete along sides and front; submarginal pronotal stria complete along sides, just turning anterior corner, the marginal bead markedly convex; elytron with single, complete epipleural stria, with a rather uniform row of punctures along its inner edge; outer subhumeral stria variably present in basal and apical halves, typically interrupted and basally fragmented (nearing absent), inner absent, dorsal stria one slightly abbreviated from apex, striae 2-4 complete, 4 th arched to suture, 5 th pre-sent in apical 1/2, sutural stria in apical 2/3, all striae formed by punctures connected by a thin stria; propygidium with large, elongate secondary punctures separated by ~ their widths, those of pygidium smaller and sparser, densest in basal corners; prosternal keel emarginate at base, striae separate basally, evenly convergent to meet ~ 1/4 from presternal suture; prosternal lobe short, bluntly triangular, lacking marginal stria; mesoventrite produced, with complete marginal stria continued at sides by postmesocoxal stria, which ends posterolaterad mesocoxa; mesometaventral stria bluntly angulate at middle, reaching middle of mesoventrite, continued at sides by lateral metaventral stria toward, but ending short of, inner 1/3 of metacoxa; metaventrite and 1 st abdominal ventrite impunctate; 1 st abdominal ventrite with incomplete lateral stria along inner margin of metacoxa; protibia with outer margin rounded, weakly dentate, with five or six marginal spines; male protarsus with flattened ventral setae; meso-and metatibiae slender, with marginal spines largely restricted to apical one-third. Male: basal piece ~ 1/4 length of tegmen; tegmen with sides subparallel to near apex, then apex roundly expanded, strongly curved in lateral view, medioventral process absent; median lobe ~ 3/4 tegmen length, basal apodemes abruptly thinner near tips.

Phelister sparsus
Etymology. The name sparsus is meant to contrast with the earlier fimbriatus, referring to the setae of the apex of the male 8 th sternite.
Remarks. Like several members of this group, this species is relatively elongate, with weakly rounded sides, strongly convex, and with relatively inconspicuous ground punctation. It is somewhat generalized within the group, lacking the oddly modified, 'scalloped' tibiae seen in a few species. This species, P. trigonisternus, P. pretiosus, and P. globosus also have two small sensory patches in place of the basal antennal annulus (at least on the ventral/anterior face), have the elytral striae serially punctiform (variably, but always to a great degree), and the males have flattened protarsal setae. Among these, P. sparsus is distinguished by the combination of a broadly oval prescutellar impression, a complete lateral submarginal pronotal stria, the lack of a prosternal lobe stria, the presence of ~ 20 larger secondary lateral pronotal punctures, and an outer subhumeral stria that is present basally and apically, but interrupted in the middle.
Distribution. This species is mainly found in lower Amazonian portions of Brazil, as well as in French Guiana and Suriname. Diagnostic description. Length: 1.97-2.17 mm (avg. 2.10 mm); width: 1.65-1.93 mm (avg. 1.84 mm). This species is also very closely related to P. sparsus, differing principally in the following characters: sides more broadly rounded; prosternal keel striae united by a transverse stria basally, enclosing a rather small triangular space ~ 3/4 as long as keel; prosternal lobe with marginal stria present; middle angle of mesometaventral stria only reaching basal fourth of mesoventrite; abdominal ventrite one with row of secondary punctures along anterior margin; male with aedeagus narrower, less curved in lateral view, with medioventral process that barely protrudes beneath; tergite 10 partially divided. Male: basal piece ~ 1/4 length of tegmen; tegmen widest near middle, evenly narrowed to base and apex, apex subtruncate; tegmen weakly curved, rather flat in lateral view, weak medioventral process present in basal 1/3; median lobe ~ 2/3 tegmen length, basal apodemes thin.
Etymology. This species name means 'precious', in reference to its jewellike appearance.
Distribution. This species is known from only a few specimens from Amazonian Ecuador and Suriname.
Remarks. The external characters listed in the description to distinguish this species are all relatively minor, but consistent. It lacks the labral fovea of P. trigonisternus Map 5. Collecting records for Phelister pretiosus (black circles), P. trigonisternus (black squares) and P. globosus (stars). and exhibits secondary punctures along the anterior margin of the 1 st abdominal ventrite that P. sparsus lacks. The male genitalia are also quite distinctive, with the tegmen sides being straighter than others (Fig. 6H vs. 6B, D, F, and 6J). Phelister trigonisternus is closely related and very similar to the two described above (P. sparsus & P. pretiosus), differing principally in the following characters: head (frons) slightly broader, distinctly widened above antennal bases; labrum depressed on anterior surface, appearing foveate; lateral submarginal pronotal stria weak to obliterated by larger, more conspicuous lateral pronotal punctures (submarginal stria basically obsolete except for a few connected punctures in some); 5 th dorsal stria present in apical 1/3, sutural stria in apical 1/2; striae of prosternal keel weakly united along basal margin; mesometaventral stria reaching basal 1/3 of mesoventrite, lateral metaventral stria nearly reaching middle of metacoxa (longer and displaced laterad from its course in P. sparsus). Male: basal piece ~ 1/3 length of tegmen; tegmen weakly widened at middle, evenly narrowed to base and apex, apex subtruncate; tegmen weakly curved in lateral view, slightly humped near base, weak medioventral process present in basal 1/3; median lobe ~ 2/3 tegmen length, basal apodemes thin.

Remarks.
The impressed labrum of this species is unique among the species in this paper. This species was described only from 'Amer.
[ica]', so the type locality is very imprecisely known. The closest match we were able to make was with a specimen from Pará, Brazil. It matches the lectotype very well in most characters but differs slightly in that the type lacks a basal fragment of the outer subhumeral stria, has a weaker frontal stria, and has the lateral pronotal punctation slightly sparser.
Distribution. This species is known from central to northeastern Brazil and Suriname. Diagnostic description. Length: 1.58-1.59 mm (avg. 1.58 mm); width: 1.26-1.38 mm (avg. 1.32 mm). Body small, elongate oval, convex, rufescent, with ground punctation very fine and inconspicuous; supraorbital stria absent; frons narrow, smooth, depressed at middle, depression barely extending onto epistoma, the latter mostly convex; frontal stria impressed at middle with ends curved dorsad, separate from sides; labrum narrow, produced, subangulate at middle; mandibles lacking basal teeth; prescutellar area depressed, but with impression weakly defined, little larger than scutellum; pronotal disk lacking secondary punctures; median pronotal gland openings small, not distinctly annulate, 3/4 behind anterior margin; marginal pronotal stria complete along sides and front; submarginal pronotal stria complete along the sides, just turning anterior corner, the marginal bead markedly convex; elytron with single, complete epipleural stria; outer subhumeral stria present in apical 1/2 only; inner absent; dorsal stria one abbreviated from apex, obsolete in apical one-third, striae 2-4 complete, but comprising series of weakly connected punctures apically, 4 th stria arched to near suture, 5 th stria present in apical one-third as series of punctures only, sutural stria a series of punctures in apical 1/2; propygidium only very sparsely punctate; prosternal keel broad, emarginate at base, striae widely separate basally, evenly convergent to meet in anterior arc; prosternal lobe short, rounded, slightly reflexed, with marginal stria rather deeply impressed and slightly removed from edge, especially at sides; mesoventrite produced, with very fine, complete marginal stria, continued at sides by postmesocoxal stria, which ends posterolaterad mesocoxa; mesometaventral stria fine, bluntly angulate at middle, nearly reaching middle of mesoventrite, continued at sides by lateral metaventral stria to middle of metacoxa; metaventrite and 1 st abdominal ventrite impunctate; 1 st abdominal slender, weakly dentate, with five or six prominent marginal spines; protarsus of both sexes with flattened ventral setae; mesoand metatibiae slender, with few fine marginal spines. Male: basal piece ~ 1/4 length of tegmen; tegmen narrowest near base, widening slightly toward rounded apex, weakly curved and thick in lateral view, medioventral process absent; median lobe ~ 1/3 tegmen length, basal apodemes abruptly narrowed at their midpoints.

Phelister globosus
Etymology. This species name refers to its broadly rounded body. Distribution. This species is known from three widely scattered localities, Amazonian Ecuador, Mato Grosso, Brazil, and French Guiana.
Remarks. This species is also quite similar to the above three, but is the most broadly rounded and convex of them. It is also distinguished by its smaller prescutellar impression, non-annulate median pronotal gland openings; lack of lateral pronotal punctures, and frontal stria with the median portion detached from the lateral portions. Despite the disjunct localities occupied by this species, no geographic variation is apparent. Diagnostic description. Length: 1.85-2.17 mm (avg. 2.01 mm); width: 1.50-1.77 mm (avg. 1.64 mm). Body subparallel-sided, weakly elongate, slightly flattened, rufescent, ground punctation of dorsum moderately fine; frons narrow, deeply impressed along midline; supraorbital stria fine, short, detached at sides; frontal stria deeply impressed along eyes, finely impressed at middle, complete; labrum weakly emarginate at apex; mandibles lacking basal teeth; antennal club elongate; prescutellar impression semicircular, ~ 2.5 × scutellar width; pronotum lacking secondary punctures in middle third, but with sparse (varied in density) secondary punctures laterad gland openings; median pronotal gland openings ~ 3/4 behind anterior margin, distinctly annulate; lateral submarginal pronotal stria complete, curved inward at front, weakly crenulate, disk depressed along its inner edge, marginal bead convex; elytron with single, complete epipleural stria; outer lateral subhumeral stria in apical 1/2 or less, inner absent; dorsal striae 1-4 complete, 4 th arched to suture, 5 th stria present in apical 1/2, sutural stria slightly longer; propygidium with small secondary punctures uniformly separated by about their diameters, those of pygidium slightly smaller and sparser; prosternal keel broad at base, striae widely separated at base, meeting 2/3 from base, keel abruptly narrowed anterad; prosternal lobe extremely short, with marginal stria; mesoventrite short, strongly projecting, marginal stria fine, continued at side by postmesocoxal stria to middle of lateral portion of metaventrite; mesometaventral stria bluntly angulate at middle, reaching middle of mesoventrite, lateral metaventral stria reaching middle of metacoxa; metaventrite impunctate; 1 st abdominal ventrite with single row of secondary punctures along anterior margin; protibiae narrow, outer margin 'scalloped', with a close set series of fine incisions, each with a minute spine, the apical-most spine larger; protarsal setae of male not modified; mesotibia with rather dense series of fine marginal spines, those of metatibia fewer, sparser, and principally restricted to apical 1/2. Male: basal piece sp. nov. 1/4 length of tegmen; tegmen with sides subparallel in basal 2/3, narrowed to thin, blunt, slightly divergent apices; weakly curved, thickened at middle in lateral view; medioventral process absent; median lobe ~ 1/3 tegmen length, basal apodemes abruptly narrowed at basal 1/3.
Etymology. This species name refers to the somewhat 'serrate' protibiae, shared with the very similar following species.
Remarks. This species and the next one (P. geminus) share one very distinctive character, having what we've previously referred to as 'scalloped' protibial margins (Fig. 2G), with very small, closely set marginal spines and no development of marginal teeth. While unusual, a similar form of protibia also occurs in the P. umens subgroup, not obviously related to this one. Phelister serratus and P. geminus are also rather elongate, parallel-sided, and relatively impunctate, with depressed pronotal margins, a quite vertical head, and a narrow frons. These two species are, however, extremely similar, and difficult to distinguish, even in male genitalia. However, we feel that the differences we have observed are sufficiently marked and consistent to recognize them as distinct (see Fig. 7C, D vs. 7E, F): P. serratus is narrower in body form, with the pronotal disk less strongly depressed along the inner edge of the lateral submarginal stria, has the median portion of the frontal stria attached to the lateral portions, and is generally more strongly punctate, both in ground punctation and in secondary pronotal punctures.
We have generated some DNA sequence data for individuals of each from the same (type) locality, and, while we have not successfully sequenced the barcoding gene for both, they are distinct in 18S sequence, which also supports the hypothesis that they are distinct. We have selected these respective DNA vouchers as the type specimens of each.
Central American specimens of P. serratus tend to show a few distinctive variants, but not consistently; often they have the prosternal keel less strongly narrowed toward the front, and the lateral epistomal ridges may appear striate. We considered separating these as distinct, but for now leave this as a widespread and variable species. In part for this reason, we have restricted the type series to a relatively small number of localities in eastern Ecuador and Colombia, and northern Peru.
Distribution. This common and widespread species is known from Costa Rica southward to Bolivia, east to the Guianas and Amazonian Brazil, with one record from coastal Brazil (Espírito Santo). Diagnostic description. Length: 1.65-2.05 mm (avg. 1.89 mm); width: 1.50-1.77 mm (avg. 1.62 mm). This species is extremely similar to the preceding (P. serratus), but differs consistently in being broader in body form (Fig. 7E), having the median portion of the frontal stria detached from the lateral portions rather than continuous across the frons, the pronotal disk more strongly depressed along the lateral margin, and in having sparser dorsal ground punctation, along with slightly lower density of secondary lateral pronotal punctures. The male genitalia exhibit no obvious differences from that of the P. serratus (Fig. 8C, D).
Etymology. This species name refers to its being a near twin of the preceding. Distribution. This species' distribution broadly overlaps the preceding, covering much of northern South America. It does not extend into Central America, however, and records are very few in the Guianas.
Remarks. As discussed under the preceding species, these are two very similar species, easily distinguished from all others by their unusual protibiae, but minimally different from each other. The description covers all characters that we have been able to find to distinguish them. We have restricted the type series to a relatively small number of localities in eastern Ecuador and Colombia, and northern Peru.  . This species is very similar to several others in this group, especially P. blairi and to P. erwini, but is unique in a few characters: body elongate (Fig. 7G), almost parallel-sided, with sides weakly rounded, dark rufescent, with conspicuous ground punctation; frons and epistoma deeply depressed along midline, sparsely but doubly punctate; pronotal gland openings just under halfway back on pronotal disk; pronotal disk with conspicuous secondary punctures throughout, sparser but distinct in middle third; marginal pronotal stria broken with inner ends recurved briefly behind eyes; submarginal pronotal stria short and weakly impressed, in anterior corners only; both propygidium and pygidium with dense secondary punctures; prosternal lobe very short, rounded. Male: basal piece ~ 1/3 length of tegmen; tegmen with sides weakly rounded, apices subacute, weakly separated; tegmen weakly curved, flatter toward apex, in lateral view; weak medioventral process present in basal 1/3; median lobe ~ 1/2 tegmen length, basal apodemes abruptly thinner near bases.
Etymology. We name this species for the state of its primary occurrence, Paraná, Brazil. Distribution. This species is only known from a relatively small area in coastal southeastern Brazil.

Phelister asperatus
Etymology. This species name refers to its asperate, or rough appearance. Distribution. This species is only known from the type locality, Brazil: Rio de Janeiro.
Remarks. This species is straightforward to recognize, particularly assuming it is restricted in distribution to southeastern Brazil. It has an unusual pattern of sculpture, with the pronotum densely doubly punctate, and the elytra less densely and mostly singly punctate. Among all the strongly punctate species in this group it is particularly small and elongate. Its elytral striae are also quite distinctive, appearing as double series of large punctures connected by a relatively fine stria.  small basal tooth; antennal club elongate, with extended setose patch along dorsal surface; prescutellar impression weakly triangular, about as long as, and 1.5 × as wide as scutellum; pronotum without lateral secondary punctures; median pronotal gland openings ~ 3/4 behind anterior margin, distinct, annulate; marginal pronotal stria complete along front and sides, weakly crenulate in front; lateral submarginal stria complete, barely turned inward anteriorly, the marginal bead weakly convex; elytral epipleuron with single, complete marginal stria; outer subhumeral stria present basally and apically, narrowly interrupted at middle, inner subhumeral stria present in apical 1/2 to 2/3; dorsal striae 1-3 complete, stria four present but fragmented along most of its length, with distinct basal arch to suture, stria five very weakly impressed in apical 1/2, sutural stria complete, meeting basal arch; propygidium with few larger secondary punctures sparsely intermingled with dense ground punctation; pygidium with dense ground punctation only; prosternal keel emarginate at base, striae complete, separate at base, converging to middle, close and parallel anteriorly, united in narrow apical arch; keel with distinct, annulate gland openings; prosternal lobe rounded, with complete marginal stria; mesoventrite produced, with complete marginal stria continued at sides by postmesocoxal stria nearly to middle of lateral portion of metaventrite; mesometaventral stria bluntly angulate at middle, reaching middle of mesoventrite, continued by lateral metaventral stria to middle of metacoxa; mesoventrite, anterior and lateral portions of metaventrite, and sides of 1 st abdominal ventrite with conspicuous, transversely reticulate microsculputure; 1 st abdominal ventrite with single, incomplete lateral stria, also with distinct, annulate gland opening along inner edge of stria; protibia with outer margin distinctly dentate, with five marginal spines; male protarsal setae not expanded; meso-and metatibiae similar, weakly expanded to apex, with few marginal spines mostly confined to apical 1/2. Male: basal piece ~ 1/3 length of tegmen; tegmen with sides widening toward apical 1/4, then narrowed to blunt apices; tegmen rather flat, weakly curved in lateral view; medioventral process present in basal 1/3; median lobe ~ 2/3 tegmen length, basal apodemes abruptly thinner near bases.
Distribution. This species is known only from French Guiana and Suriname.
Etymology. This species name refers to the mixed, or 'miscellaneous,' small and large punctures on the dorsum.
Distribution. This species is known from southern Peru and south-central Brazil.

Phelister inbio
Etymology. By this species name we honor the institution and effort that was the Instituto Nacional de Biodiversidad (INBio), now part of the MNCR. The parataxonomists and professional taxonomists engaged in the effort to document Costa Rica's biodiversity provided a successful model to which the rest of the world could aspire.
Distribution. This species is only known from Costa Rica.
Remarks. This species is very distinctive, particularly among the Central American Exosternini fauna. Its narrow, uniformly doubly punctate pronotum, broadly oval prescutellar impression, complete outer subhumeral stria with basomedial extension, and basally connected 4 th and sutural elytral striae distinguish it from anything else in the region.  along midline; supraorbital stria present at middle, obsolete at sides; frontal stria complete; epistoma obliquely subcarinate along sides; labrum emarginate and subcarinate apically; mandibles each with small basal tooth; antennal club with elongate setose patch on dorsal surface; prescutellar impression wide, forming a short rounded triangle 2-3 × as wide as scutellum; median pronotal gland openings present ~ 2/3 back from anterior margin, distinctly annulate; pronotal punctation doubled throughout, but more sparsely so in middle third; marginal pronotal stria complete along sides and front; submarginal pronotal stria complete, raised, close to margin, barely turning anterior corner; elytron with two complete epipleural striae; outer subhumeral stria complete, inner subhumeral nearly complete, obsolete at base; dorsal striae 1-4 complete, the 4 th arched to and usually connected to the sutural, 5 th slightly abbreviated from base, sutural stria complete or nearly so; prosternal keel narrow, emarginate at base, striae separate at base, evenly converging to near apex, united anteriorly; prosternal lobe shortly, weakly reflexed, with marginal stria complete; mesoventrite produced, with complete marginal stria continued at sides by postmesocoxal stria, ending behind mesocoxa; mesometaventral stria angulate at middle, crenulate, reaching middle of mesoventrite, continued at sides by lateral metaventral stria nearly reaching outer 1/3 of metacoxa; 1 st abdominal ventrite with incomplete lateral stria along inner margin of metacoxa; protibia with outer margin strongly dentate, with ~ five marginal spines; protarsal setae of male not flattened; meso-and metatibiae slightly broadened, with a few spines along outer margins. Male: basal piece nearly 1/2 length of tegmen; tegmen narrow at base, expanded then subparallel over most of length, apices rounded, slightly separated; tegmen flattened, slightly curved in lateral view; medioventral process present, projecting at basal fourth; median lobe ~ 1/2 tegmen length, basal apodemes abruptly narrowed at bases.

Phelister sculpturatus
Distribution. This species ranges from southeastern Mexico, through Central America to south-central Brazil.
Remarks. This widespread and variable species has much in common with P. praedatoris, especially in the nearly complete coverage of ground and secondary punctation. However, P. sculpturatus always has its inner elytral striae distinct amongst the punctures, is slightly more elongate in overall body form, and has the protibia less strongly dentate. The distributions of the two species don't appear to overlap, with P. sculpturatus known only from cerrado and western Amazonia in South America (beyond its more typical range in Central America). Like P. praedatoris, it appears to be an army ant associate, having been collected a few times (in both Peru and Panama) in Eciton bivouacs, though most records come only from flight interception traps. er; median pronotal gland openings nearer halfway back from anterior margin; frontal stria obsolete in median depression, frons with distinct microsculpture; antennal club with two distinct dorsal and one ventral setal sensory patch basal to elongate median patch (Fig. 11C); propygidium more coarsely and densely punctate; protibia slightly broader; lateral metaventral stria divergent toward mesepimeron. Male not known.
Etymology. This species name, tunki, is the local name of the Andean cock-ofthe-rock (Rupicola peruvianus), a beautiful and popular bird in the area, for which the lodge at the type locality was named.
Distribution. This species is only known from the type locality, Cusco, Peru. Remarks. Although this species is known only from a singleton, from a locality on the margin of the range of its closest relative P. sculpturatus, there are enough clear morphological differences between the two to support its separate species status. Reichensperger, 1939Figs 11E, F, 12C, D, Map 8 Phelister praedatoris Reichensperger, 1939: 281. Phelister praedatorius Mazur, 1984: 284, 1997: 28, 2011.
Distribution. While the species is well represented in collections, it seems still only to be known from the type locality (in Santa Catarina, Brazil), and only in association with army ants (both Labidus and Eciton are recorded as hosts).
Remarks. Phelister praedatoris was one of the first species in this group to be described, and it remains among the most distinctive, with its inner elytral striae largely obliterated by dense secondary elytral punctation. Few other species treated here are as thoroughly doubly punctate, including on the thoracic and abdominal ventrites, the principal exceptions being the species treated immediately below. Additional distinctive characters include its unusually strongly dentate protibiae, and a raised outer subhumeral stria that almost forms a lateral elytral margin (aligned with the strongly raised marginal pronotal bead). Diagnostic description. Length: 3.27-3.43 mm (avg. 3.35 mm); width: 2.80-2.84 mm (avg. 2.82 mm). Body elongate oval, slightly depressed, dark rufescent, with conspicuous double punctation throughout, the ground punctation coarse and uniformly intermingled with moderately large secondary punctures; frons rather broad, depressed along midline; supraorbital stria present at middle; frontal stria interrupted at middle; epistoma subcarinate along sides; labrum emarginate and subcarinate apically; mandibles each with small basal tooth; antennal club elongate, with small setose patch near apex of dorsal surface; prescutellar impression small and weak; median pronotal gland openings obscured by punctures, but distinctly annulate and present about midway from anterior margin; marginal pronotal stria complete around lateral and anterior margins; lateral submarginal pronotal stria complete, pronotal disk weakly impressed along its inner edge; elytron with single, complete epipleural stria; outer subhumeral stria interrupted at middle, inner absent; all dorsal striae finely impressed as a series of punctures, complete, with 4 th arched to sutural, 5 th not quite attaining basal arch; pygidia densely punctate; prosternal keel emarginate at base, striae separated at base, sinuate to united apex; prosternal lobe rounded, with marginal stria complete; mesoventrite produced, its marginal stria complete, continued by postmesocoxal stria toward anterior third of mesepimeron; mesometaventral stria weakly impressed, bluntly angulate at middle; lateral metaventral stria diverging to side, barely separated from postmesocoxal; 1 st abdominal ventrite with incomplete lateral stria along inner edge of metacoxa; all ventrites punctate; all tibia slightly broadened; protibia with outer margin strongly dentate, bearing four or five marginal spines; protarsal setae of male not flattened; meso-and metatibiae slightly broadened, mesotibia with several conspicuous spines along outer margins, those of metatibia fewer and finer. Male: basal piece 1/3 length of tegmen; tegmen narrow at base, weakly and unevenly expanded to near apex, Map 8. Collecting records for Phelister vazdemelloi (black circles), P. praedatoris (white star), P. ifficus (black squares), P. genieri (hexagon), and P. marginatus (black stars). apices rounded; tegmen flattened, mostly straight but apically curved in lateral view; medioventral process present, projecting at basal fourth; median lobe ~ 1/2 tegmen length, basal apodemes abruptly narrowed at bases.

Phelister ifficus
Etymology. This species name is a play on the full binomial, together forming -ter ifficus, in reference to its attractive morphology.
Distribution. This species only known from two localities, in the Andean foothills of central Peru and Bolivia.
Remarks. This species seems to be part of a monophyletic lineage, also comprising the following three species. Phelister ifficus is much more densely punctate than the most similar of them, P. vazdemelloi, as well as more elongate, yet not markedly flattened or laterally explanate like P. genieri and P. marginatus are. The two available specimens of this species differ slightly in the appearance of the prescutellar area, the Peruvian specimen having a very weak depression, and the Bolivian one having only a tiny smooth area with a puncture. Diagnostic description. Length: 2.52-2.76 mm (avg. 2.64 mm); width: 2.21-2.40 mm (avg. 2.30 mm). Body broadly rounded, depressed, sides explanate, rufescent, with very dense and conspicuous ground punctation throughout; frons rather broad, depressed along midline; supraorbital stria absent; frontal stria complete; epistoma subcarinate along sides; labrum emarginate and subcarinate apically; mandibles each with small basal tooth; antennal club elongate, with small setose patch near apex of dorsal surface; prescutellar impression absent; median pronotal gland openings small, obscured by punctures, but present ~ 2/3 from anterior margin; marginal pronotal stria complete, fine, continued around anterior margin; submarginal pronotal stria present close to marginal as a raised carina, disk deeply depressed along its inner edge; elytron with single, complete epipleural stria; outer subhumeral stria complete beneath strong lateral elytral carina, which may be the complete inner subhumeral stria; dorsal striae shallowly impressed but distinct, all complete, with 4 th arched to sutural; pygidia densely covered with elongate punctures, pygidium weakly differentiated, with flat anterodorsal surface and short, curved posteroventral surface, similarly punctate throughout; prosternal keel slightly depressed, emarginate at base, striae obsolete; prosternal lobe weakly reflexed, with marginal stria complete; mesoventrite produced, its marginal stria weakly impressed, continued by postmesocoxal stria toward but not reaching middle of mesepimeron; mesometaventral stria weakly impressed, angulate at middle; lateral metaventral stria diverging to side, subparallel to postmesocoxal; 1 st abdominal ventrite with incomplete lateral stria along inner edge of metacoxa; all ventrites punctate; all tibia slightly broadened; protibia with outer margin strongly dentate, bearing four or five marginal spines; protarsal setae of male not flattened; meso-and metatibiae slightly broadened, with a few spines along outer margins. Male: basal piece 1/3 length of tegmen; tegmen narrow at base, weakly and unevenly expanded to near apex, apices rounded; tegmen quite flattened, only weakly curved in lateral view; medioventral process present, projecting at basal fourth; median lobe almost 1/2 tegmen length, basal apodemes abruptly narrowed at bases.
Etymology. We are pleased to name this species in honor of François Génier, collector of the type, and contributor of numerous valuable specimens to our histerid studies.
Distribution. This species is only known from the type locality, Cochabamba, Bolivia. Remarks. As described above, this species is part of a related lineage comprising the preceding one and following two species. It is particularly close to P. marginatus but is easily distinguished by the much coarser dorsal punctation, and distinct elytral striae. Its body is also not so broad, and its sides less broadly explanate.  . Body broadly rounded, depressed, sides explanate, rufescent, with very dense and conspicuous ground punctation throughout; frons rather broad, moderately depressed along midline; supraorbital stria absent; frontal stria interrupted across median depression; epistoma subcarinate along sides; labrum emarginate and subcarinate apically; mandibles each with small basal tooth; antennal club elongate, with small setose patch near apex of dorsal surface; prescutellar impression absent, at most faintly depressed; median pronotal gland openings small, obscured by punctures, but present ~ 2/3 from anterior margin; marginal pronotal stria complete, fine, continued around anterior margin; submarginal pronotal stria present close to marginal as a raised carina, disk deeply depressed along its inner edge; elytron with single, complete epipleural stria; outer subhumeral stria complete beneath strong lateral elytral carina, which may be the complete inner subhumeral stria; dorsal striae faintly impressed, only a few vaguely traceable, primarily the complete sutural stria; propy- gidium flat, densely covered with elongate punctures, pygidium with flat anterodorsal surface punctate, and short, curved posteroventral surface impunctate but shagreened; prosternal keel narrowed, emarginate at base, striae narrowly separate at base, converg-ing and subparallel to near apex, united anteriorly; prosternal lobe reflexed, with marginal stria complete; mesoventrite produced, its marginal stria only faintly impressed; postmesocoxal stria present, not reaching mesepimeron; mesometaventral stria absent across middle; lateral metaventral stria forming a short stria parallel to postmesocoxal; all ventrites punctate; all tibia slightly broadened; protibia with outer margin strongly dentate, bearing four or five marginal spines; protarsal setae of male not flattened; meso-and metatibiae slightly broadened, with a few spines along outer margins. Male: basal piece 1/3 length of tegmen; tegmen narrow at base, evenly widened, rounded to near apex, apices rounded; tegmen curved to apex in lateral view; medioventral process present, projecting at basal fourth; median lobe ~ 1/3 tegmen length, basal apodemes abruptly narrowed at bases.

Phelister marginatus
Etymology. The name of this species refers to the carinate margins of the pronotum and elytra.
Distribution. This species is known only from Costa Rica, from Limón and Puntarenas provinces.
Remarks. As described above, this species is part of a related lineage comprising the preceding two and the following species. Phelister marginatus is easily distinguished by its broad, flattened, laterally carinate and explanate body, along with its largely effaced elytral striae. Diagnostic description. Length: 2.05-2.44 mm (avg. 2.25 mm); width: 1.85-2.29 mm (avg. 2.05 mm). Body rather broadly rounded, widest behind elytral humeri, rufescent, with conspicuous ground punctation throughout, the pronotum with uniformly dense secondary punctation as well; frons depressed along midline; frontal stria obsolete within median depression; epistoma broad, with raised edges along sides and front; labrum emarginate, weakly subcarinate along apical margin; mandibles lacking basal teeth; prescutellar impression not evident; median pronotal gland openings only slightly larger than secondary punctures, ~ 1/3 behind anterior margin, distinctly annulate; marginal pronotal stria complete along lateral and anterior margins; submarginal stria complete, well-impressed along lateral margin, just turning anterior corner; elytron with single, complete epipleural stria; outer subhumeral stria present at base and apex but interrupted at middle; inner subhumeral stria present at middle but obsolete at ends; all dorsal striae complete, 4 th arched to sutural, with 5 th nearly meeting basal arch; pygidia with moderately coarse secondary punctation; prosternal keel emar-ginate at base, striae separate at base, converging, meeting ¾ of the distance to apex, united anteriorly; prosternal lobe weakly reflexed, with marginal stria complete; mesoventrite weakly produced, with complete marginal stria continued at sides by postmesocoxal stria ending laterad mesocoxa; mesometaventral stria angulate at middle, crenulate, reaching middle of mesoventrite, continued at sides by lateral metaventral stria, reaching middle of metacoxa; 1 st abdominal ventrite with nearly complete lateral stria along inner margin of metacoxa; metaventrite with coarse secondary punctation; 1 st abdominal ventrite with secondary punctures largely limited to anterior third; protibia with outer margin weakly dentate, with five or six robust marginal spines; mesoand metatibiae slender, the mesotibia spinose along most of outer margin, metatibia with marginal spines finer and restricted to apical 1/2. Male: basal piece 1/3 length of tegmen; tegmen narrow at base, widest at basal 1/3, then rounded, narrowing to apex, apices rather thin, slightly separated; tegmen very flattened, straight with weak apical curve in lateral view; medioventral process present, projecting at basal fourth; median lobe ~ 1/2 tegmen length, basal apodemes abruptly narrowed at bases.

Phelister vazdemelloi
Etymology. This species is named in honor of our friend and colleague, Fernando Vaz-de-Mello. Fernando's lab and the collection he runs (CEMT) have provided many specimens to our studies, and he and his students graciously hosted the authors during a 2011 field trip to Mato Grosso.
Distribution. This species is only known from Mato Grosso, Brazil.
Remarks. This species and the preceding three (P. marginatus, P. genieri, and P. ifficus) form a closely related lineage within this group. All have lost a distinct prescutellar impression and are considerably larger in body size than average for the group. All also have more or less 'complete' elytral striation, uniformly double (ground and secondary) punctation on the dorsum, and have slightly expanded and strongly punctate protibiae. Phelister vazdemelloi is the least modified of these, with relatively sparse dorsal punctation, and a convex body. Diagnostic description. Length: 2.96-3.51 mm (avg. 3.21 mm); width: 2.56-3.84 mm (avg. 2.70 mm). Body large, elongate oval, strongly convex, castaneous to piceous; most surfaces conspicuously punctate; head with frons depressed along midline, produced above antennal bases, ground punctures not reticulate; supraorbital stria absent; frontal stria complete, continued above epistoma, also apparently continued anterad by lateral marginal epistomal carina; epistoma not constricted at base, elevated along anterior margin, labrum short, apex weakly emarginate; mandibles with incisor edges rather short, each with weak basal marginal tooth; pronotum broad, uniformly densely punctate; distinct prescutellar impression absent, prescutellar area only faintly depressed; median pronotal gland openings simple, not annulate, located ~ 2/3 from anterior margin; lateral submarginal stria complete, deeply impressed; lateral marginal stria complete and continuous with anterior marginal; elytron with one complete epipleural stria and a secondary epipleural striole between it and the margin over the metafemur; outer subhumeral striae complete, with outer basal appendix (i.e., appearing y-shaped); inner subhumeral slightly abbreviated from base; all other dorsal striae complete, 5 th stria arched to sutural; punctures of elytral disk distinctly interconnected by fine reticulations; propygidium large, midline length equal to that of pygidium; prosternal keel emarginate at base, with primary striae anteriorly connected ~ 1/3 short of presternal suture, divergent at base; secondary striae present along basal 1/2 of keel; prosternal lobe rounded, with complete marginal stria; mesoventrite with strong median projection; marginal mesoventral stria may be weakly interrupted at middle, continued by postmesocoxal stria nearly to metepisternum; mesometaventral stria strongly angulate at middle, extending anteriad to anterior third of mesoventrite, extending to mesocoxa at sides, not directly connected by lateral metaventral stria, which extends posterolaterally to posterior third of metepisternum; 1 st abdominal ventrite with single, incomplete lateral stria along inner edge of metacoxa; all tibiae (but not femora) broadly expanded; protibia with inner edge straight, outer edge deeply toothed, with five marginal spines; tarsi compressed, the tarsomeres together little longer than the tibiae are broad. Male: basal piece long, > 1/2 length of tegmen; tegmen widest near base, narrowed at basal 1/3, then weakly widening to apex, apices rounded; tegmen rather thick, mostly straight with weak apical bend in lateral view; medioventral process present, projecting at basal fourth; median lobe ~ 1/2 tegmen length, basal apodemes abruptly narrowed at bases.

Distribution. This species is only known from French Guiana.
Remarks. This is a distinctive species, superficially quite similar to P. amazoniae and P. arcuatus in the large convex body size with expanded tibiae (which we assert to be convergences). But the non-explanate pronotum and 'normal', non-expanded femora of the present species will easily separate it from the others. Its anteriorly split (y-shaped) outer subhumeral stria is unique among species treated in this paper.  . Body large, elongate, dark-rufescent, nearly parallel-sided, smooth, with fine inconspicuous ground punctation; supraorbital stria complete, forming a carina between upper margin of eyes; frons broad, widened anteriorly, deeply depressed at middle; frontal stria complete, raised as a sinuate transverse carina; epistoma deeply depressed at middle, sides raised, subcarinate; labrum wide, emarginate; mandibles lacking basal teeth; antennal club elongate; pronotum lacking prescutellar impression, disk without secondary lateral punctures; pronotal gland openings small, annulate, located just beyond middle of disk; lateral submarginal pronotal stria complete, deeply impressed, curving inward and joining anterior marginal stria, marginal bead raised laterad; anterior marginal stria separated from lateral portions of marginal stria; elytra with single, complete epipleural stria; outer subhumeral stria complete, forming a strong lateral marginal carina, other dorsal striae reduced, those present displaced laterad, carinate, inner subhumeral present as very short apical carina, stria one complete, 2 nd present in apical 2/3, 3 rd represented only by scratch-like basal vestige; other dorsal striae absent; propygidium with depressions on either side, disk with secondary punctures mainly at sides; pygidium with broken marginal stria, disk punctate along lateral and apical margins; prosternal keel elevated, narrow, emarginate at base, with complete striae united anteriorly; prosternal lobe short, marginal stria complete; mesoventrite deeply sulcate at sides, raised along midline, marginal stria obscured; postmesocoxal stria present, recurved to mesepimeral-metepisternal corner; mesometaventral stria absent at middle, lateral metaventral stria very short, divergent, ending freely behind mesocoxa; median portions of metaventrite and 1 st abdominal ventrite im-punctate, the latter with incomplete lateral stria along metacoxa; protibia with outer margin strongly dentate, with five marginal spines; male protarsus with modified setae; meso-and metatibiae with fine marginal spines. Male: basal piece 1/4 length of tegmen; tegmen narrow at base, weakly expanded to just beyond middle, narrowed to rounded apices; tegmen flattened at base and apex, thicker in middle in lateral view; medioventral process absent; median lobe ~ 1/3 tegmen length, basal apodemes narrower toward bases.

Phelister spectabilis
Etymology. The 'spectacular,' highly autapomorphic general morphology of this species inspires its name.
Distribution. This species is known from two disjunct areas, Amazonian Ecuador and Colombia in the west, and French Guiana far to the east.
Remarks. This very distinctive species is easily recognized by its elongate body form, carinate outer elytral striae, and obsolete inner elytral striae (including the sutural stria). The deep pits on the mesoventrite are also unique among Neotropical Exosternini. It lacks a distinct prescutellar impression, and its relationship to others in this group is not very clear. Its annulate pronotal gland openings near the middle of the pronotal disk do seem to support relationships somewhere in this group, however.
Specimens from the rather disjunct areas reported here differ somewhat. In Guianan specimens the frons is slightly broader, the supraorbital stria is connected to the frontal stria at the sides; the lateral submarginal pronotal stria is joined to the anterior marginal, and the lateral epistomal carinae is less prominent. Even the aedeagus is a bit more parallel-sided and apically quadrate. We considered separating these as distinct, but expect that additional specimens from intervening gaps will fill these minor morphological gaps.   1.49 mm). Body rounded, convex, dark rufescent, with moderately conspicuous ground punctation; frons narrow, depressed along midline; supraorbital stria complete, detached at sides from frontal; frontal stria interrupted across depression; epistoma depressed at middle, sides weakly elevated; labrum weakly emarginate; each mandible with subacute basal tooth; sides of pronotum rather abruptly narrowed in anterior third; prescutellar impression subtriangular, rounded at base, ~ 1.5 × width of scutellum; pronotal disk with secondary punctures in lateral thirds; median pronotal gland openings small, annulate, rather widely separated, ~ 2/3 behind anterior margin; marginal pronotal stria complete around front and sides; submarginal striae absent; elytron with single, complete epipleural stria; outer subhumeral stria very short, apical, inner absent; dorsal stria one slightly abbreviated from apex, striae two and three usually complete, becoming fragmented apically, striae four and five represented by series of apical punctures, 4 th also represented by strong, transverse basal arch; sutural stria present in apical 2/3, also becoming series of punctures toward apex; propygidium uniformly punctate, secondary punctures separated by ~ 1.5 × their diameters; pygidium much more finely and sparsely punctate; prosternal keel very broad, shallowly emarginate at base, lacking striae; prosternal lobe very short, also lacking marginal stria; mesoventrite weakly rounded in front, with fine marginal stria continued by very short, fine postmesocoxal stria; mesometaventral stria strongly crenulate, arched forward to middle of mesoventrite, continued by very short lateral metaventral stria; metaventrite and 1 st abdominal ventrite impunctate, but 1 st abdominal ventrite with distinct, annulate gland opening mesad metacoxa; protibia slender, outer margin rounded, weakly dentate, with ~ four marginal spines; male with flattened ventral protarsal setae; meso-and metatibiae very slender, with few fine marginal spines toward apex. Male: basal piece 1/3 length of tegmen; tegmen narrow at base, weakly expanded to near apex, apices rounded; tegmen slightly curved in lateral view; medioventral process absent; median lobe ~ 3/4 tegmen length, basal apodemes long, thin.
Etymology. The name pervagatus approximately translates to widespread, common, which is very true of this species.
Distribution. This species occurs across tropical South America, found in the Guianas, Ecuador, Peru, Bolivia, and across much of central and northern Brazil.
Remarks. This species is quite consistent in its morphology throughout its broad range. It can be easily recognized by its round (not very elongate) body form, broad prosternal keel lacking striae, short prosternal lobe, laterally flattened pronotal margins, lack of lateral submarginal pronotal stria, and apically serially punctate elytral striae. We restrict the type series to a small number of localities around eastern Ecuador (from which we have obtained DNA sequences) and northern Peru.
While the vast majority of specimens of P. pervagatus have been collected by flight interception traps, a few specimens have been collected in leafcutter ant (Acromyrmex hystrix) refuse piles, as well as in dung-baited pitfalls.

P. amazoniae subgroup
This small group of eleven species is well characterized by distinctive genitalic characters. We have only found two external characters that typically co-occur with these, and P. geijskesi is an exception to both of them.
Etymology. With two specimen records coming from carrion traps, this species is named for its 'morbid' apparent interest in dead carcasses.
Distribution. This species is only known from a couple localities in east-central Brazil (Rio de Janeiro and Minas Gerais).
Remarks. This species can best be recognized by the combination of its detached central portion of the frontal stria, the relatively broad prosternal keel, and the lack of a stria along the margin of the prosternal lobe. Due to the broad distributional gap between the known localities, we restrict the type series to the single holotype specimen from Minas Gerais (from which we illustrated the male genitalia).  Diagnostic description. Length: 2.40-2.56 mm (avg. 2.44 mm); width: 1.89-2.25 mm (avg. 2.08 mm). Body elongate, sides almost subparallel, dark rufescent to piceous, with conspicuous ground punctation; frons broadly impressed along midline, with sparse small punctures intermingled with ground punctation; supraorbital stria present, detached at sides; frontal stria complete, fine; epistoma raised along lateral and anterior margins; labrum emarginate, apical margin subcarinate; mandibles lacking basal teeth; prescutellar impression semicircular, slightly wider than scutellum; pronotal disk with doubly punctate, with numerous secondary punctures intermingled with ground punctation, denser toward sides; median pronotal gland openings distinctly annulate, just > 1/2 behind anterior margin; marginal pronotal stria complete along sides and front; submarginal pronotal stria complete, deeply impressed, close to margin, barely curving inward at front; elytron with single complete epipleural stria; outer subhumeral stria present at base and apex, briefly interrupted at middle in most individuals; inner subhumeral stria fragmentarily present at middle, rarely nearly complete; dorsal striae 1-4 complete, the 4 th arched to the sutural, 5 th obsolete in basal fourth, sutural stria complete; all elytral striae weakly crenulate; pygidia densely doubly punctate, with fine and secondary punctures uniformly intermixed; prosternum emarginate at base, striae divergent at base, sinuate to, and meeting at, apex; prosternal lobe short, with complete marginal striae; mesoventrite produced, with complete marginal stria continued at sides by postmesocoxal stria, which ends behind outer corner of mesocoxa; mesometaventral stria angulate at middle, reaching anterior third of mesoventrite, continued at sides by lateral metaventral stria to middle of metacoxa; metaventrite with ground punctation denser toward midline (particularly in males), with secondary punctures interspersed near metacoxae; 1 st abdominal ventrite with secondary punctures along anterior margin, lateral stria incomplete along inner margin of metacoxa; protibia weakly expanded, outer margin with ~ five spinose denticles; meso-and metatibiae also weakly expanded, with rather conspicuous marginal spines; ventral setae of all tarsi flattened (those of protarsus, particularly). Male: basal piece 1/3 length of tegmen; tegmen with sides subparallel in basal 1/3, abruptly narrowed to long, downturned apical portion; medioventral process absent; median lobe short, thick.

Phelister annulatus
Etymology. This species name refers to the annulate pronotal punctures (though this character is common to many species in the group).
Distribution. Most specimens of this species have been collected in northeastern Brazil and French Guiana. However, it is also known from Amazonian Ecuador and Peru, as well as Mato Grosso, Brazil.
Etymology. This species name, sphaericus, refers to its very convex body form. Distribution. This species has an unusual distribution, with the highest concentration of records coming from northeastern Brazil, Suriname, and French Guiana, but with a number also from central Brazil and Bolivia to the southwest.

Phelister geijskesi
Distribution. Though described only from Suriname, this species in fact has a wide distribution along the east coast of northern South America, even extending to the island of Trinidad.
Remarks. This species stands out among those treated here in having the frons simply convex, not at all impressed medially. It is also distinctive in having the scutellar impression broadly oval, and punctate within, and in having the elytral striae weakly carinate (the outer edge of the stria is elevated, while the inner edge is flat). In some respects (including its Atta association) the species resembles Pseudister rufulus (Lewis) (and a few others we consider related to it, such as Phelister rubens Marseul), which shares a convex frons, deeply emarginate labrum, and spinose tibiae. However, analyses to date don't support these as closely related. Instead P. geijskesi exhibits numerous features that ally it to the species above, including distinctly annulate pronotal gland openings ~ 2/3 removed from the anterior margin (those of Pseudister are non-annulate and close to the margin), depressed male mesoventrite, and anterior narrowing of the prosternal keel, in addition to genitalic features. Diagnostic description. Length: 3.15-3.43 mm (avg. 3.32 mm); width: 2.76-3.11 mm (avg. 2.98 mm). Body large, rounded, strongly convex, castaneous; most surfaces conspicuously punctate, with small ground punctation and significantly larger punctures rather sparsely intermingled; head with frons depressed along midline, weakly produced above antennal bases; supraorbital stria present, disconnected from frontal stria at sides; frontal stria complete, continued finely above epistoma; epistoma laterally weakly carinate, weakly constricted at base, elevated along anterior margin; labrum short, apex weakly emarginate; left mandible with weak basal tooth; pronotum broad, with punctures larger and denser toward prescutellar area; prescutellar impression absent; median pronotal gland openings annulate, located ~ 2/3 from anterior margin; lateral submarginal stria complete, strongly impressed; lateral marginal stria complete and continuous with anterior marginal; elytron with one complete epipleural stria; outer subhumeral striae complete, inner subhumeral slightly abbreviated from base; all other dorsal striae complete, 1 st -3 rd subcarinate, 5 th arched to sutural stria; propygidium large, midline length equal to that of pygidium; prosternal keel emarginate at base, with primary striae anteriorly connected, posteriorly divergent; secondary striae present along basal 1/2 of keel; prosternal lobe rounded, marginal stria absent; mesoventrite with strong median projection; marginal mesoventral stria complete, postmesocoxal stria short, ending behind coxa; mesometaventral stria weakly angulate at middle, reaching anterior third of mesoventrite, continued by lateral metaventral stria to inner 1/3 of metacoxa; metaventrite and anterior 1/2 of 1 st abdominal ventrite conspicuously punctate; 1 st abdominal ventrite with single, incomplete lateral stria along inner edge of metacoxa; protibiae weakly expanded, with inner edge weakly rounded, outer edge weakly 5-dentate, each tooth with small spine; meso-and metatibiae not distinctly expanded, tarsi not compressed. Male: basal piece 1/4 length of tegmen; tegmen with sides subparallel in basal 2/3, abruptly narrowed to ventrally curved apices; medioventral process absent; median lobe ~ 1/4 tegmen length.
Etymology. We name this species fraternus as a reference to the 'brotherhood' of three similar but non-identical specimens we have available of the species.
Distribution. The entirety of material available for this species is three specimens from three disparate locations (the type locality in French Guiana, plus Santa Cruz, Bolivia and Mato Grosso, Brazil).

Remarks.
In having the posterior 1/2 of the pronotum increasingly densely punctate, this species resembles species of Crenulister. This shared character may be informative, although they do not resolve together in preliminary phylogenies. This is true of the following two species newly described here, as well, having some characters of Crenulister, but resolving apart from it in results of analyses to date.
There is some variation among the specimens studied. The Brazilian example has a more nearly complete inner subhumeral stria, while the one from Bolivia has only a few basal fragments. The Brazilian specimen's pronotum is also faintly explanate. Diagnostic description. Length: 4.02-4.65 mm (avg. 4.32 mm); width: 3.90-4.10 mm (avg. 4.03 mm). Body very large, elongate oval, strongly convex, piceous; ground punctation conspicuous, most surfaces with conspicuous but sparse secondary punctures; head with frons weakly depressed along midline, weakly produced above antennal bases; supraorbital stria present, disconnected from frontal stria at sides; frontal stria interrupted at middle; epistoma weakly elevated at sides; labrum with apex emarginate; left mandible with moderate basal tooth; pronotum broad, with secondary punctures more numerous in posterior 1/2; prescutellar area weakly depressed; main median pronotal gland openings weakly annulate, with one pair at anterior margin, also apparently multiplied along a short track reaching 2/3 from anterior margin; lateral submarginal stria complete, strongly impressed; lateral marginal stria complete and continuous with anterior marginal; anterior margin weakly produced behind head; elytron with one complete epipleural stria; outer subhumeral, inner subhumeral and all dorsal striae complete, 4 th arched toward base of 5 th , but free, 5 th arched to sutural stria, all striae connected by apical arches along elytral apex; propygidium midline length nearly equal to that of pygidium; prosternal keel emarginate at base, with primary striae narrowly connected in front, posteriorly divergent but connected along basal margin; weak secondary striae present along basal 1/2 of keel; prosternal lobe short, emarginate apically, marginal stria absent; mesoventrite with strong median projection; marginal mesoventral stria complete, slightly disconnected from postmesocoxal stria, which extends just beyond mesocoxa; mesometaventral stria broadly angulate at middle, reaching anterior third of mesoventrite, continued by lateral metaventral stria toward, but not reaching, middle of metacoxa; metaventrite with cluster of secondary punctures near metacoxa; 1 st abdominal ventrite conspicuously punctate in anterior 1/2, with incomplete lateral stria along inner edge of metacoxa; protibia weakly expanded, outer edge weakly dentate, each tooth with small spine; meso-and metatibiae not distinctly expanded, tarsi not compressed. Male: basal piece 1/3 length of tegmen; tegmen with sides subparallel in basal 1/2, abruptly narrowed, then weakly expanded to ventrally hooked apices; medioventral process absent; median lobe ~ 1/4 tegmen length.

Phelister conjunctus
Etymology. This species name refers to the apically 'conjunct' or united elytral striae. Distribution. This species is only known three close locations in French Guiana.
Remarks. This species appears very closely related to P. fraternus (above), and as discussed under that species, has much in common with species we have assigned to Crenulister. It lacks the large, spatulate protarsal setae of Crenulister, and has quite dissimilar genitalia. Otherwise, compared to those and to P. fraternus, it has finer and sparser pronotal punctation, and has its pronotal gland openings apparently multiplied, with two or three openings in a longitudinal series, with larger irregular surrounding annuli. All its elytral striae are complete and most are also connected along the elytral apex. Diagnostic description. Length: 2.56 mm; width: 2.13 mm. Body elongate oval, slightly flattened, rufescent; ground punctation fine, with very few, larger secondary punctures; head with supraorbital stria weakly connected to frontal stria at sides; frontal stria complete, slightly recurved at middle; epistoma with sides and apical margin subcarinate; labrum with apex emarginate; left mandible lacking basal tooth, right mandible with very small basal tooth; pronotum broad, with secondary punctures more numerous toward prescutellar area, prescutellar impression small, poorly defined; median pronotal gland openings small, non-annulate, approximately 1/3 from anterior margin; lateral submarginal stria complete, strongly impressed; anterior margin weakly produced behind head; elytron with single, complete epipleural stria; outer subhumeral stria complete, crenulate; inner subhumeral stria absent; dorsal striae 1-5 and sutural stria complete, the 4 th arched to base of sutural stria, all striae appearing as series of connected punctures, the punctures alternating sides of the connecting line; propygidium with sparse secondary punctures mostly in basal 1/2; pygidium narrowed to apex, bluntly acute, lacking secondary punctures; prosternal keel deeply emarginate at base, somewhat broad, striae subparallel, connected in front, posteriorly divergent; prosternal lobe deflexed, rounded, with complete marginal stria; mesoventrite with strong median projection; marginal mesoventral stria complete, continued by postmesocoxal stria to mesepimeron; mesometaventral stria angulate at middle, reaching anterior third of mesoventrite, continued by lateral metaventral stria to middle of metacoxa; metaventrite and anterior 1/2 of abdominal ventrite one with dense secondary punctures; abdominal ventrite one with incomplete lateral stria along inner edge of metacoxa; protibia weakly expanded, with outer edge rounded and strongly dentate, with ~ 8 marginal spines; protarsal ventral setae expanded, leaf-like; meso-and metatibiae not distinctly expanded, with numerous long marginal spines; meso-and metatarsi slender, with long ventral spines.
Etymology. We name this species for Dr. Caroline Chaboo, in recognition of her exceptional work on documenting the beetle fauna of Peru.
Distribution. This species is only known from the type locality in Madre de Dios, Peru.
Remarks. This species may represent a connection between this group of Phelister and the recently described genus Crenulister (Caterino and Tishechkin 2014). We have debated whether it belongs there, lacking a few characters of that genus (and lacking confirmation from male genitalia). It shares some characters, including the broadly rounded and moderately flattened body form, the strongly spinose tibiae, the more conspicuous secondary punctures along the posterior portion of the pronotal disk, the broadly crenulate elytral striae, and the spatulate tarsal setae (not restricted to males). However, it differs from most of them in lacking a pygidial stria, lacking an inner subhumeral elytral stria, and having the middle of the anterior pronotal margin rather distinctly produced over the head. For now, we describe this distinct species in Phelister, and recognize that the relationships between these genera requires further examination. emarginate at base, striae convergent to apex; prosternal lobe rather long, subtruncate, with deep, complete marginal striae; mesoventrite strongly produced, with complete marginal stria continued at sides by postmesocoxal stria, which ends freely at middle of lateral portion of metaventrite; mesometaventral stria angulate at middle, reaching middle of mesoventrite, continued at sides by lateral metaventral stria to inner 1/3 of metacoxa; 1 st abdominal ventrite with one complete and one incomplete lateral striae; protibia rather strongly dentate, with ~ five marginal spines; spines of meso-and metatibiae fine and long, but largely confined to distal 1/2; ventral setae of tarsi simple, not flattened. Male: basal piece 1/3 length of tegmen; tegmen with sides subparallel in basal 2/3, abruptly narrowed to ventrally hooked apices; medioventral process absent; median lobe ~ 1/3 tegmen length.

Phelister striatinotum
Distribution. This species is very widely distributed, from Costa Rica in the north to Argentina in the south, with most other records coming from western Amazonia. The species is also known from the Guianas.
Remarks. This is a widespread and rather variable species. The very wide prescutellar impression, with its anterior margin distinctly sinuate, is its most consistent diagnostic feature. This, along with pronotal gland openings that are near the anterior third of the pronotal disk, will identify it unambiguously. Compared to other species treated in this paper, its frons is relatively weakly depressed, and the tooth on the base of the left mandible is quite strong. Its relationships to species immediately above are not very strongly supported, since this species has a completely divided male 10 th tergite (it is partly or completely fused in all the preceding species of the amazoniae subgroup).
Nearly all specimens have been collected using flight interception traps. However, one specimen from La Selva, Costa Rica was 'Riding [an] Atta Cut Leaf ', suggesting that leafcutter ant nests would be worth exploring for this species. Diagnostic description. Length: "3 mm" (Schmidt 1893b). Body rounded, slightly elongate, widest behind humeri, rufescent, with rather dense and conspicuous ground punctation; frons broad, depressed at middle; supraorbital stria absent; frontal stria strongly recurved at middle briefly interrupted; labrum shallowly emarginate at apex; prescutellar impression weakly impressed, narrower than scutellum; pronotal disk with few lateral secondary punctures; median pronotal gland openings annulate, ~ 4/5 behind anterior margin; marginal pronotal stria complete along sides and front; submarginal stria absent; elytral striae very reduced, crowded to side; outer subhumeral stria interrupted but present at base and apex; inner subhumeral present in apical 2/3; striae one and two complete; stria three present at base only; 4 th , 5 th and sutural striae absent except for basal arch; propygidium large, as long along midline as pygidium, with dense ground punctation and only slightly larger secondary punctures interspersed; pygidium largely lacking secondary punctures; prosternal keel emarginate at base, striae convergent to apex; prosternal lobe short, with fine marginal striae; mesoventrite produced, with complete marginal stria continued at sides by postmesocoxal stria, which ends freely at middle of lateral portion of metaventrite; mesometaventral stria sinuate at middle, reaching nearly to mesoventral stria, continued at sides by lateral metaventral stria toward metepipleuron; abdominal ventrites obscured by point; all tibiae slightly broadened; protibia strongly dentate, with ~ five marginal spines; spines of meso-and metatibiae weak, most confined to distal 1/2.

Phelister notandus Schmidt, 1893
Distribution. This species is only known from the type, with only the unfortunately vague location "Brasil".
Diagnostic description. Length: 2.72-3.11 mm (avg. 2.95 mm); width: 2.40-2.64 mm (avg. 2.56 mm). Body large, elongate, with sides subparallel, strongly convex, dark rufescent to castaneous; most surfaces densely punctate; head with frons depressed along midline, strongly produced above antennal bases, densely punctate, punctures interconnected by fine reticulations; supraorbital stria present, but disconnected from frontal at sides; frontal stria complete along sides, weakly continued above epistoma, may be finely interrupted at middle, also continued anterad by lateral marginal epistomal striae; epistoma constricted at base, swollen along anterior margin, labrum short, apically emarginate; mandibles with incisor edges rather short, without marginal teeth; pronotum broad, densely punctate, most punctures uniform in size, disk explanate along sides; prescutellar impression smaller than scutellum, weakly defined; median pronotal gland openings distinctly annulate, located ~ 2/3 from anterior margin; lateral submarginal stria complete, deeply impressed; lateral marginal stria complete and continuous with anterior marginal; elytral subhumeral striae and all dorsal striae complete, outer striae deeply impressed and carinate, 4 th stria arched to sutural stria; punctures of elytral disk distinctly interconnected by fine reticulations; propygidium large, midline length equal to that of pygidium, with two sizes of punctures (small and smaller) intermingled, intervening surface finely microsculptured; pygidium with deep, complete marginal stria, punctation finer and denser than that of pygidium; prosternal keel deeply emarginate at base, narrowed, with median striae complete, subparallel, connected anteriorly; prosternal lobe short, rounded, with complete marginal stria; mesoventrite rather narrow, with strong median projection; marginal mesoventral stria may be weakly interrupted at middle, continued by postmesocoxal stria to outer 1/4 of metaventrite; mesometaventral stria angulate at middle to midpoint of mesoventrite, continued by lateral metaventral stria to middle of metacoxa, then by recurrent stria anterad to middle of metepisternum; 1 st abdominal ventrite with broadly depressed, complete lateral stria along inner edge of metacoxa; all femora and tibiae broadly expanded; protibia with rounded inner and outer edges, with four or five marginal spines, spurs present, small; meso-and metafemora with posterior margin strongly produced; meso-and metatibiae broad and flat, with weak marginal spines; tarsi stout, compressed, together little longer than the tibiae are broad. Male: basal piece just > 1/3 length of tegmen; tegmen with sides subparallel to slightly widened in basal 1/2, abruptly narrowed to ventrally hooked apices; medioventral process absent; median lobe simple, ~ 1/3 tegmen length.
Remarks. Although this species was described from Pará state, Brazil, all recent material we have seen is from much further south and west, from Mato Grosso to Amazonian Peru. Nonetheless, the distinctive characters are clearly shared with the type specimen.
This species is very similar and closely related to the following one, but the presence of a pygidial stria in the present species will consistently distinguish them. In most specimens of P. amazoniae, the pronotal punctation is simple, comprising consistentsized punctures, and the elytral punctures are joined by a very fine network of reticulations. Specimens of P. amazoniae from Peru (Madre de Dios, La Convencion) tend to have a doubly punctate pronotum, like P. arcuatus, as well as non-reticulate elytral punctation, but based largely on their possessing a marginal pygidial stria we retain these here. These two species are also very similar to another new species (P. dilatatus, #23 above), which also shares the large convex, generally punctate body, as well as broadly expanded tibiae. However, remarkably, this appears to be convergence, as the male genitalia are quite different. Phelister dilatatus is also easily distinguished by the non-explanate pronotum and distinctly toothed (not externally rounded) protibia.
This species has previously been assigned to a genus of Haeteriinae. However, it clearly lacks critical characters of that subfamily (fused labrum, pyramidal antennal scape, sclerotized sides of antennal club, lack of tibial spurs), and is only superficially similar to members of Reninus Lewis. Among other characters, its male genitalia clearly ally it to this subgroup of the Phelister blairi group.

Phelister arcuatus
Etymology. This species' name refers to the strongly outwardly bowed 4 th (and other) elytral striae.
Distribution. This species is known from Pará and Mato Grosso states, Brazil.
Remarks. This species is broadly sympatric with the preceding, but the differences are consistent across this range, particularly the lack in the present species of a marginal pygidial stria. Both species are known from males and females, precluding the possibility that their differences represent sexual dimorphism.

P. gregarius subgroup
This subgroup comprises six species, united by a number of characters. Of them, the divided medioventral process of the aedeagus seems to be a strong synapomorphy.
Etymology. This species name refers to its apparent predilection for socializing with army ant colonies, from which several records originate.
Distribution. This is a relatively common species, known from many specimens over a broad area from Costa Rica south to Peru, and east to Paraná, Brasil. Remarks. Despite this species' wide range, it is relatively consistent in morphology, and readily identifiable, by the rounded triangular shape of its prescutellar impression, relatively sparse lateral secondary punctures on the pronotum, and presence of only a short fragment of the submarginal pronotal stria in the anterior corners. It also appears to be unique in showing a distinct sexual dimorphism, with the males' metaventrite being medially depressed as well as bearing a field of very short, almost imperceptible, scale-like setae. A few other species show a faint depression in males, but none as distinct as here.
Two specimens from Santa Cruz, Bolivia, and one from Junín, Peru have a complete lateral submarginal pronotal stria, and have pronotal microsculpture (like P. rudis), but have sparser dorsal sculpturing and an unbroken anterior marginal pronotal stria, so are ambiguous. We place these here for now, but additional material will be necessary to fully assess patterns of character variation. Specimens from Suriname have the lateral submarginal pronotal stria almost absent, represented by only a very short arc in the anterior corners.  Diagnostic description. Length: 1.89-2.17 mm (avg. 2.03 mm); width: 1.58-1.93 mm (avg. 1.71 mm). Body elongate oval, dark rufescent, with conspicuous ground punctation throughout; frons depressed along midline; supraorbital stria present, ends free; frontal stria complete, fine at middle; frontal disk with ground punctation but lacking secondary punctures; epistoma broad, with edges raised, subcarinate; labrum weakly emarginate; left mandible with blunt basal tooth, that of right mandible small, subacute; pronotum slightly elongate, sides weakly convergent; prescutellar impression broadly oval, ~ 4 × as wide as scutellum; median pronotal gland openings ~ 2/3 behind anterior margin, distinctly annulate; pronotal disk with numerous secondary punctures at sides; marginal pronotal stria complete along lateral and anterior margins, very close to margin anteriorly; submarginal stria present at sides and front, lateral portion complete (French Guiana) or abbreviated (others), anterior portion detached from lateral, briefly recurved behind eyes; elytron with single, complete epipleural stria; outer subhumeral stria fine, nearly complete, slightly abbreviated at base, inner subhumeral absent; dorsal striae 1-4 complete, 5 th present in apical 3/4 and as short basal arch, sutural stria slightly longer than 5 th , obsolete at base; propygidium with secondary punctures separated by ~ 1.5 × their diameters; pygidium with only few small secondary punctures along base; prosternal keel shallowly emarginate at base, striae united at base and apex, enclosing narrow area; secondary striae present along basal 1/2 of keel; prosternal lobe slightly reflexed, with complete marginal stria; mesoventrite weakly produced, with very fine, complete marginal stria continued laterally by postmesocoxal stria to middle of lateral portion of metaventrite; mesometaventral stria weakly angulate at middle, reaching anterior third of mesoventrite, continued at sides by lateral metaventral stria; lateral metaventral stria extending from mesometaventral suture to near outer 1/3 of metacoxa; metaventrite with few small secondary punctures near metacoxa; 1 st abdominal ventrite with complete inner and partial outer lateral striae along inner margin of metacoxa; protibia with outer margin strongly dentate, with five or six marginal spines, apical corner with shallow emargination (mediad apical spine); protarsi of male with flattened ventral setae; meso-and metatibiae with rather long, fine marginal spines. Male: basal piece wide, ~ 1/3 length of tegmen; tegmen with sides subparallel in basal 1/2, then widened to spoon-shaped apex; apical lobes produced laterally over main body of tegmen; medioventral process present, weak, not projecting ventrally, divided at middle; median lobe ~ 1/2 tegmen length, basal apodemes narrowed.
Diagnostic description. Length: 1.69-1.89 mm (avg. 1.80 mm); width: 1.42-1.54 mm (avg. 1.48 mm). This species is extremely similar to the preceding two (P. gregarius and P. praecisus), differing principally in the following characters: frons with microsculpture within frontal depression; prescutellar impression broadly semi-oval; mandibles each with distinct basal tooth; pronotum with marginal stria continuous around sides and front; submarginal pronotal stria present in anterior 1/2 at sides, anterior portion broken and recurved behind eyes; outer subhumeral elytral stria present in apical 1/2 only, rarely with detached basal appendix (especially in Peruvian examples); prosternal keel weakly narrowed anteriorly, with striae complete, united anteriorly only; prosternal lobe short; mesometaventral stria strongly angulate to near marginal mesoventral stria; male metaventrite not depressed; protibia with apical spine prominent, other marginal spines rather fine and slightly separated from it. Male: basal piece broad, short, ~ 1/3 length of tegmen; tegmen with sides subparallel in basal 1/2, then widened slightly to rounded apices, thick and notably curved in lateral view; medioventral process absent; median lobe ~ 1/2 tegmen length, with basal apodemes widely separated. Etymology. The name rudis, or rough, refers to the unusual microsculpture of the frons. Distribution. This species is known from Panama as well as much of western Amazonia, from Ecuador to Bolivia.
Remarks. We assign specimens from a broad area, ranging from Panama, southward along western South America to Bolivia, to this species. However, we restrict the type series to Panamanian specimens, as there is some variation, and other areas are poorly represented. Most specimens (all those from the type locality) exhibit distinct microsculpture within the frontal depression. This is quite unusual in this group, and within Phelister as a whole (being otherwise occasional in some Operclipygus spp.). The species is quite similar in other respects to P. gregarius and P. praecisus. From the former it consistently differs by its broadly oval prescutellar impression (subtriangular in P. gregarius) and the broken anterior submarginal pronotal stria. From P. praecisus it differs in having a shorter outer subhumeral stria, and prosternal keel striae that are not united at the base. Specimens from Peru tend to have several metaventral punctures, which is otherwise only found in P. gregarius (at least among these species), but these males don't have a depressed metaventrite, as those of P. gregarius do.   1.85 mm). Body elongate oval, convex, variably rufescent, with very conspicuous ground punctation everywhere, on pronotum uniformly intermingled with secondary punctation; frons weakly depressed; supraorbital stria present, ends free; frontal stria fine, complete; epistoma broad, with edges raised; labrum wide, deeply emarginate; left mandible with short, blunt basal tooth, that of right mandible small, acute; prescutellar impression slightly elongate, only slightly wider than scutellum; median pronotal gland openings obscured by punctation, possibly absent; marginal pronotal stria complete along lateral margin; lateral submarginal stria complete, con-tinuous with marginal stria behind head; elytron with single, complete epipleural stria; outer subhumeral stria fine, present at base and apex, narrowly interrupted at middle, inner subhumeral absent; dorsal striae 1-5 and sutural complete, 5 th arched to sutural stria; propygidium with small secondary punctures sparsely intermingled with ground punctation, that of pygidium finer and mainly in basal 1/2; prosternal keel weakly emarginate at base, striae united at base and apex, secondary striae present along basal 1/2 of keel, keel narrowed anteriorly; prosternal lobe short, with complete marginal stria; mesoventrite weakly produced, with complete marginal stria continued laterally by postmesocoxal stria which ends behind posterior corner of mesocoxa; mesometaventral stria arcuate across middle, reaching middle of mesoventrite, continued at sides by lateral metaventral stria to middle of metacoxa; metaventrite of male weakly depressed, with very dense ground punctation, with larger secondary punctures near metacoxa; metaventrite of female flat, with larger secondary punctures; 1 st abdominal ventrite with two incomplete lateral striae, the anterior 1/2 of disk with dense secondary punctures; protibia with outer margin weakly dentate but strongly spinose, with five or six marginal spines, the apical most particularly prominent, with a shallow emargination along apical margin; meso-and metatibiae with rather long, fine marginal spines largely restricted to distal halves. Male: basal piece narrow, ~ 1/3 length Map 14. Collecting records for Phelister gregarius (circles), P. rudis (black squares), and P. incongruens (stars). of tegmen; tegmen with sides subparallel in basal 2/3, abruptly narrowed to hooked apices; medioventral process present, projecting at basal 1/3 of tegmen, divided at middle; median lobe ~ 1/2 tegmen length, abruptly narrowed to bases.

Phelister incongruens
Etymology. The name refers to the very different, incongruous, punctation on the pronotum vs. the elytra.
Distribution. This species is known only from a couple of localities in French Guiana.
Remarks. This species is distinct in the distribution of surface sculpture, with its ground punctation conspicuous everywhere, that on the pronotum uniformly interspersed with coarse secondary punctation (not restricted to sides). Additionally, the venter exhibits distinct macrosculpture all over. The interrupted outer subhumeral stria is an unusual character but is seen in a few other species in this group. It is particularly similar to P. praesignis but has the secondary punctation of the pronotum larger yet slightly sparser, and the ground punctation of the pronotum and especially the elytra distinctly finer. It is also more broadly rounded, and has a complete submarginal pronotal stria, absent in P. praesignis.
While all (five) specimens of this species are from French Guiana, they fall into two distinct size classes, with the smaller ones (two males, one female) also lighter in color. However, no other differences are apparent, and we assume we have not captured the full range of variation with so few specimens. Diagnostic description. Length: 1.38-1.77 mm (avg. 1.56 mm); width: 1.22-1.58 mm (avg. 1.37 mm). Body elongate oval, convex, rufescent, with very conspicuous ground punctation, and no secondary punctation throughout; frons depressed along midline; supraorbital stria present, ends free; frontal stria complete; epistoma broad, with edges raised; labrum emarginate; left mandible with short, blunt basal tooth, that of right mandible small, acute; prescutellar impression semicircular, ~ twice as wide as scutellum; median pronotal gland openings obscured by ground punctation, but apparently present ~ 3/4 behind anterior pronotal margin, within a small elongate impunctate area, not distinctly annulate; marginal pronotal stria complete along lateral and anterior margins; submarginal stria absent; elytron with single, complete epipleural stria; outer subhumeral stria fine, present at base and apex, interrupted at middle, inner subhumeral absent; dorsal striae 1-5 complete, 5 th arched to sutural, the sutural stria obsolete in basal one-sixth; propygidium with secondary punctures separated by ~ 1.5 × their diameters; pygidium with only few small secondary punctures along base; prosternal keel subtruncate at base, striae united at base and apex, secondary striae present along basal 1/2 of keel; prosternal keel and meso-& metaventral disks of male bearing very short scale-like setae; prosternal lobe short, with complete marginal stria; mesoventrite not, or only weakly produced, with complete marginal stria continued laterally by postmesocoxal stria to middle of lateral portion of metaventrite; mesometaventral stria arcuate across middle, reaching middle of mesoventrite, continued at sides by lateral metaventral stria; lateral metaventral stria extending from mesometaventral suture to near middle of metacoxa; metaventrite of male not depressed; 1 st abdominal ventrite with complete inner displaced mediad, and partial outer lateral striae along inner margin of metacoxa; protibia with outer margin weakly dentate but strongly spinose, with five or six marginal spines, apical corner with shallow emargination (mediad apical spine); protarsi of male with ventral setae not flattened; mesotibia with rather long, fine marginal spines in apical 1/2, those of metatibia very fine to obsolete. Male: basal piece elongate, slightly > 1/3 length of tegmen; tegmen with sides unevenly subparallel in basal 3/4, abruptly narrowed to hooked apices; medioventral process present, projecting at basal 1/3 of tegmen, divided at middle; median lobe ~1/2 tegmen length, basal apodemes abruptly narrowed.

Phelister congruens
Etymology. This species name is meant to contrast with the above (P. incongruens), given the similar, congruous, punctation of its pronotum and elytra.
Distribution. This species is only known from a fairly small area in Amazonian Colombia, Ecuador and northeastern Peru.
Distribution. This species is known from two rather widely separated localities, in Amazonian Peru as well as southern Pará (Brazil).
Remarks. This species is quite similar to the preceding two (P. incongruens and P. congruens), with strong dorsal punctation especially on the pronotum. These also share the distinctive non-spinose metatibia. Phelister praesignis is narrower in overall body form than these, and has the secondary pronotal punctation denser, though the individual secondary punctures are not as large as those of P. incongruens. In P. congruens, the pronotal punctation, while dense, is entirely composed of finer ground punctures. The slightly swollen anterior pronotal corners of P. praesignis are also unique.

P. umens subgroup
This subgroup comprises five species, defined principally by the 'scalloped' protibia (a convergence with that of P. geminus and P. serratus, we believe) and the apically fringed eighth male sternite.
Etymology. This species name, umens, means wet or humid, referring to this species' Amazonian rainforest habitat.
Distribution. Records of this species extend from Amazonian Ecuador east along the Amazon River to Pará, Brazil, as well as to the northeast in Suriname and French Guiana. Remarks. The members of this small species group are all quite similar, having more or less 'scalloped' protibiae, weak to obsolete prosternal keel striae, the 1 st elytral stria tending to be obsolete posteriorly, and the lateral pronotal margin somewhat compressed, or bent down outside the submarginal stria. Among these, P. umens is distinguished in external characters by having the lateral submarginal pronotal stria slightly abbreviated posteriorly (in others it may be either more complete, or substantially abbreviated), having the subhumeral striae absent, and in having quite dense propygidial punctation. Other material. Brazil: Paraná [sic] Tucuruí, Sept. 1984, FIT (CHND 1ex.). This specimen is labelled as written. However, Tucuruí is in Pará state. Whether this specimen is in fact from this disjunct locality seems unlikely, and we suspect it is from some other locality in Paraná.

44.
Diagnostic description. Length: 1.54-1.81 mm (avg. 1.68 mm); width: 1.26-1.50 mm (avg. 1.37 mm). Body elongate oval, weakly depressed, dark rufescent, with fairly conspicuous ground punctation; frons broad, distinctly widened anteriorly, weakly depressed in middle, supraorbital stria complete, meeting frontal stria at sides, frontal stria complete, sinuate through depression; epistoma depressed at middle, sides raised; labrum sinuate, not emarginate, at apex, each mandible with very small basal tooth; prescutellar impression oval, barely larger than scutellum; pronotal disk with few secondary punctures near sides; marginal pronotal stria complete along sides and front, occasionally joining end of submarginal behind eye, thus interrupted; lateral submarginal stria obsolete in basal 1/2, continuing around anterior angle, ending freely near anterior marginal stria or joining it; median pronotal gland openings annulate, slightly > 1/2 pronotal length behind anterior margin; elytron with single, complete epipleural stria; outer subhumeral stria present in apical 1/2, inner absent; dorsal stria one weakened to obsolete in apical 1/2, striae two and three complete,  striae four and five both present in apical 1/2, sutural stria present in apical 2/3; propygidium with secondary punctures separated by about their diameters at base, sparser posterad; pygidial secondary punctures smaller and sparser; prosternal keel shallowly emarginate at base, striae separated at base or weakly joined along basal margin, united anteriorly; prosternal keel-lobe junction slightly narrowed, lobe short, rounded, with complete marginal stria; mesoventrite wide and short, produced anteriorly at middle, with fine marginal stria continued at side by short postmesocoxal stria which ends behind mesocoxa; meso-metaventral stria angulate at middle, reaching middle of mesoventrite; lateral metaventral stria diverging, ending freely at middle of lateral portion of metaventrite; metaventrite impunctate; 1 st abdominal ventrite with lateral stria complete or interrupted at gland opening mesad posterior corner of metacoxa; protibia with outer margin sinuate, 'scalloped', mainly in apical 1/2; meso-and metatibiae with fine marginal spines mainly in apical halves. Male: S8 with setal fringe; aedeagus with basal piece ~ 1/3 length of tegmen; tegmen with sides subparallel in basal 2/3, abruptly narrowed to bluntly rounded apices, largely straight in lateral view; medioventral process absent; median lobe ~ 5/6 tegmen length, basal apodemes thick over most of their lengths abruptly narrowed at extreme bases. Etymology. We name this species in honor of Dr. Lúcia Massutti de Almeida, of the Universidade Federal do Paraná, in recognition of her mentorship of several outstanding histeridologists, and in gratitude for her hospitality to the authors during a 2011 visit.
Distribution. This species is only known from a few localities, all within Paraná (Brazil).
Remarks. This species is very similar to the preceding, but differs in a number of respects, having the prescutellar impression elongate oval and only slightly larger than the scutellum, the pronotal gland openings more anterior, a more strongly abbreviated lateral submarginal pronotal stria, an outer subhumeral present apically, and having the 3 rd dorsal elytral stria complete. Ventrally the prosternal keel striae are also more distinctly impressed in this species. nearly as long; prosternal keel with striae weak but present, united anteriorly. Male: S8 with apical setal fringe; aedeagus short, basal piece slightly > 1/2 length of tegmen; tegmen with sides unevenly subparallel in basal 2/3, narrowed to subacute apices, apex slightly hooked in lateral view; medioventral process very strong, produced at basal fourth; median lobe ~ 3/4 tegmen length, basal apodemes narrow throughout.

Phelister chicomendesi
Etymology. The name microdens refers to the unusual, finely dentate form of the protibia (shared with a few others treated in this paper).
Distribution. This species is known from few specimens that nonetheless cover a broad swath of tropical South America, from Bolivia to Pará, Brazil. Remarks. This species is very similar to the two above but may be distinguished by the more anterior location of the pronotal gland openings, the weak but present prosternal keel striae, and the strongly punctate elytral striae.  stria complete, meeting frontal at sides, frontal stria complete, well impressed, weakly sinuate through depression; epistoma with sides raised; labrum weakly emarginate; each mandible with very small basal tooth; prescutellar impression oval, barely larger than scutellum; pronotal disk with few secondary punctures near sides; marginal pronotal stria complete along sides and front, strongly crenulate in front; lateral submarginal stria complete; median pronotal gland openings annulate, slightly > 1/2 pronotal length behind anterior margin; elytron with single, complete epipleural stria; outer subhumeral stria present in apical one-third, inner absent; dorsal stria one weakened to obsolete in apical 1/2, stria two and three complete, striae four and five both present in apical 1/2, sutural stria in apical 2/3; propygidium with secondary punctures dense almost throughout, sparse only along posterior margin; pygidial secondary punctures smaller and sparser; prosternal keel shallowly emarginate at base, striae well-impressed joined along basal margin, slightly sinuate, united anteriorly; prosternal keel-lobe junction slightly narrowed, lobe short, rounded, with complete marginal stria; mesoventrite wide and short, produced anteriorly at middle, with fine marginal stria often interrupted at middle, continued at side by short postmesocoxal stria which ends behind mesocoxa; meso-metaventral stria bluntly angulate at middle, reaching anterior third of mesoventrite; lateral metaventral stria directed posterolaterally, nearly reaching mid-dle of metacoxa; metaventrite impunctate; 1 st abdominal ventrite with complete inner and abbreviated outer lateral striae; protibia with outer margin sinuate, 'scalloped', more weakly so in basal 1/2; meso-and metatibiae with fine marginal spines those of mesotibia more numerous and robust. Male: S8 with apical setal fringe; aedeagus with basal piece nearly 1/2 length of tegmen; tegmen with sides slightly widened to middle, evenly narrowed to bluntly rounded apices, apex slightly curved ventrally in lateral view; medioventral process very strong, produced at basal fourth; median lobe ~ 3/4 tegmen length, basal apodemes abruptly narrowed in basal 1/3.

47.
Etymology. The species name is a contraction of Mata Atlantica, the Brazilian Atlantic Forest globally recognized hotspot on which this species largely depends.
Distribution. This species is known mainly from coastal (Atlantic forest) areas of southeastern Brazil. However, it also extends inland through Santa Catarina and into Paraguay.
Remarks. While similar in most characters to other species in this group, this species is considerably larger than the others. They are also frequently faintly bicolored (redder anterad), have the lateral submarginal stria complete, and have the prosternal keel striae well impressed, united anteriorly.
Etymology. We name this species for the distinctive curved protibia (which it shares with the following species).
Distribution. This species is only known from Minas Gerais in eastern Brazil.
Remarks. This species appears closely related only to the following, and they are very similar in a few distinctive external characteristics, listed above. In addition to the surprisingly substantial genitalic differences detailed in the description, this species is typically vaguely bicolored, whereas the following species is uniformly dark. They also differ in the form of the elytral striae, where in P. curvipes all the dorsal striae are contiguous, in P. vilavelha the inner elytral striae are formed by series of disconnected punctures. Diagnostic description. Length: 1.69-1.81 mm (avg. 1.76 mm); width: 1.54-1.65 mm (avg. 1.62 mm). This species is extremely similar to the preceding (P. curvipes) in external morphology (though not in male genitalia), differing principally in the following characters: body not bicolored, more less uniformly piceous frontal ground punctation slightly more conspicuous; right mandible with strong basal tooth (possibly not a difference from the preceding, in which it could not be observed); median pronotal gland openings 2/3 behind anterior pronotal margin; lateral secondary pronotal punctures more numerous and covering most of the outer 1/4 of the pronotal disk; 1 st dorsal elytral stria obsolete in the apical 2/3; 2 nd through sutural elytral striae distinctly comprising series of disconnected punctures; 4 th stria present only in apical Map 17. Collecting records for Phelister curvipes (upright black triangle), P. vilavelha (black hexagon), P. rio (white circle), P. semotus (stars), P. uncinatus (black squares), and P. inscriptus (inverted white triangles). 2/3, 5 th stria with no basal arch; secondary pygidial punctures sparse but extending nearly to apex; prosternal keel striae obsolete in anterior 1/2; protibia more strongly curved; Male: S8 without apical processes; aedeagus with basal piece ~ 1/3 length of tegmen; tegmen slightly widened to near apex, then evenly narrowed to subacute apices, apex slightly curved ventrally in lateral view; medioventral process absent; median lobe ~ 2/3 tegmen length, basal apodemes abruptly narrowed in basal 1/3.

Phelister vilavelha
Etymology. This species is named for the Parque Estadual Vila Velha, the only known locality for this species.
Distribution. This species is only known from the type locality in Paraná, Brazil. Remarks. The differences between this species and the very similar preceding one are adequately detailed in the preceding remarks section and the description above.

P. rio subgroup
This subgroup of four rather small, broadly rounded species shares non-annulate median pronotal gland openings with the preceding group.
External characters: • Median pronotal gland openings non-annulate Etymology. This species is named as an informal reference to the type locality, Rio de Janeiro.
Distribution. This species has been recorded from a handful of localities along coastal southeastern Brazil.
Remarks. The four species within this fairly distinctive group are mostly characterized by minor external differences (despite considerable variation in aedeagal form). Phelister rio is distinguished by its wide prescutellar impression in combination with a short, apical outer subhumeral stria, complete 3 rd dorsal stria, and lack of basal arch of the 4 th or 5 th striae. The male genitalia are quite similar to those of Operclipygus, a similarity that we presently hypothesize to be a convergence.
Specimens from Minas Gerais are somewhat variable in key characters, some individuals having a smaller, oval prescutellar impression, and more coarsely punctate and posteriorly inturned elytral striae. Others, including a male, however, correspond well to the above diagnosis, and male genitalia match as well. of male more broadly than females. Male: accessory sclerites present, S8 short, but with long, setose lateral processes; T10 entire; aedeagus with basal piece slightly > 1/3 tegmen length; tegmen weakly widened beyond midpoint, then narrowing slightly to subtruncate apices; medioventral process absent; median lobe long, proximal apodemes thin, undifferentiated. Etymology. The name of this species refers to the finely 'inscribed' basal portion of the 3 rd elytral stria.
Distribution. This species is known from three widely separated localities, in Amazonian Ecuador and Peru to Guyana.
Remarks. The primary distinguishing character of this species, compared to the others in this group, is the basally abbreviated 3 rd dorsal stria, which is replaced with a very fine, scratch-like basal fragment. The protibial shape, with the rather evenly rounded, densely spinose margins, is also unusual, and the mesometaventral stria in this species is not as strongly arched forward as others in this group. A single female specimen from Guyana has the same tibia and other major characters but differs in having more conspicuous ground punctation, a larger prescutellar impression, and a more complete 3 rd dorsal stria. But lacking a male to assess aedeagus shape, we consider it to be an aberrant member of the present species for now.

Incertae sedis
A few species treated below are either not obviously closely related to any of the subgroups delimited above, or they are not represented by adequate material (males, in one case) to verify critical characters for placement. Diagnostic description. Length: 1.42-1.54 mm (avg. 1.51 mm); width: 0.91-1.34 mm (avg. 1.24 mm). Body elongate oval, convex, outline somewhat interrupted at pronotal-elytral junction, with pronotum narrower, rufescent, ground punctation very fine and inconspicuous; frons rather narrow and elongate, along with epistoma weakly depressed; supraorbital stria nearly complete, slightly abbreviated at sides; frontal stria carinate, outwardly rounded, complete; epistoma with sides and front subcarinate, almost appearing striate around edges of depression; labrum weakly emarginate; antennal club short, round, with elongate setose patch on dorsum; prescutellar impression small, elongate oval, narrower than, and about as long as scutellum; pronotal disk with few or no lateral secondary pronotal punctures; marginal pronotal stria complete along sides and front; lateral submarginal pronotal stria complete, arched around anterior corner; pronotal gland openings 3/4 behind anterior margin, widely separated, non-annulate; elytral epipleuron with single, complete stria; outer subhumeral stria in apical 1/3, inner absent; 1 st dorsal stria slightly abbreviated from apex, 2 nd complete, 3 rd complete or interrupted at middle; striae four and five very short, apical, 4 th often with short basal fragment, 5 th with basal arch connected to base of sutural, sutural stria complete or very narrowly interrupted near base; pro-and pygidium evenly, sparsely covered with conspicuous secondary punctures; prosternal keel weakly emarginate at base, striae weakly divergent anteriorly and posteriorly, free anteriorly; mesoventral process weak, with fine, complete marginal stria; postmesocoxal stria rather long, ending behind outer corner of mesocoxa; mesometaventral stria broadly arched, reaching basal 1/3 of metaventrite, not at all crenulate; lateral metaventral striae divergent toward apical one-third. Male: T10 entire; S8 with few, inconspicuous apical setae; accessory sclerites absent; aedeagus with basal piece slightly > 1/3 tegmen length; tegmen mostly parallel-sided, weakly narrowed to rounded apices; medioventral process present, weak; median lobe 3/4 as long as tegmen, with proximal apodemes undifferentiated.

Phelister incertus
Etymology. This species name refers to uncertainty with regard to its systematic placement.
Distribution. This species is known from several localities in southeastern Peru and Bolivia.
Remarks. While this species has non-annulate pronotal gland openings, like the preceding two subgroups (P. curvipes and P. rio subgroups), genitalic characters such as the complete T10 and medioventral aedeagal process make it an awkward fit in either. These characters, in combination with small body size (~ 1 mm), lack of secondary lateral pronotal punctures, and complete, basally hooked sutural stria will distinguish it from other species treated here as well as other Phelister spp. Diagnostic description. Length: 1.85 mm; width: 1.58 mm. Body elongate oval, piceous, pronotum rather narrow, with conspicuous ground punctation; frons and epistoma weakly depressed, frontal stria complete, shallowly recurved at middle; labrum weakly emarginate, apical margin not at all carinate; both mandibles with basal tooth on incisor edge; prescutellar impression forming a small rounded triangle, ~ 2 × the length and width of scutellum; pronotal disk with numerous lateral secondary punctures in outer fourths; marginal pronotal stria complete along sides and front, not crenulate anteriorly; lateral pronotal margins slightly compressed, edges turned down, flattened; lateral submarginal pronotal stria absent; median pronotal gland A B
Etymology. We take pleasure in naming this species for the collector of the only known specimen of this species, scydmaenine staphylinid specialist, Dr. Sean O'Keefe (Morehead State University, USA).
Distribution. This species is only known from Guanacaste, Costa Rica.
Remarks. This species is a bit of an outlier among those treated in this paper. It has a relatively large subtriangular prescutellar impression, and annulate pronotal gland openings ~ 1/3 behind the anterior margin. But its frons and epistoma are only very weakly impressed, its labrum is only weakly emarginate, and the left mandible (and maybe the barely visible right one) has a strong basal tooth. Together, these characters will distinguish it from any other Exosternini in Central America.
Etymology. The name of this species signifies its strong but perhaps convergent similarity to the species P. blairi.
Distribution. This widespread species is known from Amazonian Ecuador, Colombia, central Brazil, and southern Suriname.
Remarks. This species is very similar to P. blairi in a number of external characters, although genitalic morphology suggest the two are not closely related. Both have the pronotal gland openings quite far forward, at most 1/4 behind the pronotal margin, and typically have the anterior marginal pronotal stria broken and/or recurved in front of these. Phelister blairoides can be distinguished by its complete (not obsolete basally) lateral submarginal pronotal stria, and its outer subhumeral elytral stria being present basally as well as apically (though interrupted at middle), whereas P. blairi has only the apical portion of the outer subhumeral stria present. It is also considerably larger in overall body size than P. blairi. The most salient differences in male genitalia include the fully divided 10 th tergite in P. blairoides (halves fused basally in P. blairi), and the more distal position of the medioventral process in P. blairoides.
Etymology. This species name refers to the name of the bridge, Puente Piraña, near the type locality.
Distribution. This species is known only from the type locality in Orellana, Ecuador. Remarks. This species is readily distinguished by its obsolete prosternal striae and pinched prosternal keel/lobe junction, its weakly margined elytra, and median pronotal gland openings very far forward. Its relationships may lie within the blairi subgroup, based on the position of the pronotal gland openings. However, it is not otherwise very similar to others there, and male genitalia would help assess its placement.