A revision of the genus Eurhoptus LeConte, 1876 (Curculionidae, Cryptorhynchinae) of America north of Mexico

Abstract The genus Eurhoptus LeConte, 1876 is revised for America north of Mexico. Eight species are recognized including E.pyriformis LeConte, 1876, E.sordidus (LeConte, 1876), E.curtus (Hamilton, 1893), resurrected name, and five new species as follows: E.rileyi new species (type locality, Texas, Hidalgo County, Bentsen Rio Grande State Park), E.imbricatus new species (type locality, Texas, Bandera County, Lost Maples State Natural Area), E.cariniventris new species (type locality, Texas, Bandera County, Lost Maples State Natural Area), E.occidentalis new species (type locality, Texas, Brewster County, Big Bend National Park), and E.aenigmaticus new species (type locality, Alabama, Winston County, Bankhead National Forest). Descriptions or redescriptions, and images of taxonomically important structures are presented for all species. A key to the eight species is included.


Introduction
The genus Eurhoptus was established by LeConte in 1876 for the species E. pyriformis LeConte, 1876. The genus was differentiated from the closely related Acalles Schoenherr, 1825 by the pear-shaped body and a stouter antennal club. Blatchley and Leng (1916) noted the presence of a deep triangular polished impression on the first ventrite in E. pyriformis but did not notice the similar impression in A. sordidus LeConte, 1876, likely because specimens are often encrusted in dirt, and left this latter species in Acalles. It was not until Kissinger (1964) recognized this similarity in abdominal ventrite sculpture and moved Acalles sordidus LeConte into the genus Eurhoptus that the definition of the genus came to rely primarily on the presence of this variously impressed first abdominal ventrite. Until the present publication, the genus contained, in addition to these two described species from the U.S.A., nine described Mexican and Central American species (O'Brien and Wibmer 1982). Here, we add five new species and resurrect the name A. curtus Hamilton, 1893 as a valid species and not a synonym of A. sordidus LeConte, 1876. The genus is tremendously diverse from Mexico south to Panama with likely a few hundred undescribed species (Anderson and O'Brien 1996;Anderson and Ashe 2000).
At least three new species have been known to occur in the U.S. for some time (Anderson 2002), but their exact limits and relationships to the described species have remained unclear. A phylogeographic study (Caterino and Langton-Myers in press) on E. pyriformis revealed deep divisions within this species in the southeastern U.S., suggesting a more complex taxonomic situation than expected, and prompting the current attempt to more completely revise the taxonomy of the known and unknown U.S. species.
The natural history of Eurhoptus is essentially unknown. The adults are frequently sifted from various types of leaf litter, where they may feed on fungus-infested plant debris, as some related taxa are thought to do (Luna-Cozar et al. 2014). The adults are flightless, and flightless relatives in Europe have been alleged to be important indicators of well-preserved ancient woodlands (Buse 2012). This does not necessarily appear so for the North American species, which have been found in a variety of secondary forest habitats. No larvae of the genus have been found or described.

Materials and methods
Standard taxonomic procedures for the examination of pinned specimens have been used. Maps were prepared with Simplemappr (http://www.simplemappr.net). Species identifications of outlying individuals were confirmed. GenBank numbers, label data, and voucher numbers for all sequences analyzed here are provided in Suppl. material 1: Table S1. Coordinates given for specimens examined are in decimal degrees. This study was based on 1250 specimens, obtained from (or deposited in) the following collections (listed by these acronyms in 'Specimens examined' sections): In part to test the distinctiveness of the species we have recognized among Nearctic Eurhoptus, we undertook a molecular phylogenetic analysis including multiple representatives where possible, of as many species as possible. Our main questions regarded the distinctiveness of a few morphological variants related to both E. pyriformis and E. sordidus. Our data set largely relies on data generated for a population level analysis of E. pyriformis in the southern Appalachians (Caterino and Langton-Myers in press). However, we have generated a number of additional sequences for the current study, and have pruned out many redundant or highly similar sequences (mainly within E. pyriformis) for the present analysis. In total, the present analysis includes data from 87 Eurhoptus individuals, and nine outgroup Cryptorhynchinae (representatives of Acalles, Peracalles, Trichacalles, Ouroporopterus, and Trigonopterus, the last three from sequences previously published by Riedel et al. (2016). Thus, analyses were based on 96 taxa overall. These include representatives of four of the eight species we now recognize in Eurhoptus, including E. curtus, E. sordidus, E. aenigmaticus, and E. pyriformis. Extractions of pointed specimens of other species were attempted, but none succeeded. See Suppl. material 1: Table S1 for full data and GenBank accession numbers for all individuals and genes sequenced. We dissected each specimen and used the GeneJet Genomic DNA Purification Kit (ThermoFisher Scientific, Waltham, MA) to extract DNA from the dissected head and prothorax. Following tissue digestion, we removed the remaining exoskeleton and mounted the body parts as vouchers. Most vouchers are deposited in the Clemson University Arthropod Collection. We sequenced portions of four genes for this analysis. We sequenced 826 bp of the mitochondrial cytochrome oxidase I (COI) gene, which is represented in 78 individuals. The portion sequenced is from the 5' half of the gene, mainly using the primers C1-J-2183 ('Jerry') and TL2-N-3014 ('Pat'; both from Simon et al. 1994). We developed one additional forward primer to amplify some difficult lineages, C1-J-2406 (TTYACTTCAGCWACWATAATYATTGC). Three nuclear genes were targeted, mainly selecting one or two individuals for each distinct mitochondrial haplotype. These included partial sequences of the internal transcribed spacer 2 (ITS2) for 56 individuals, using the primers TW81 and HITR (from Richards et al. 1997), aligned length 1611 bp; 921 bp of the protein coding rudimentary (CAD) gene from 78 individuals, using the primers CD821F and CD1098R2 (from Wild and Maddison 2008); and 344 bp of an intron in the krotzkopf verkehrt (kkv) gene from 67 individuals using the primers KKV2768F and KKV3023R (from Polihronakis-Richmond and Caterino 2012). Amplifications via PCR started with a 3-minute initial denaturation at 95°, a 30 second denaturation at 94°, 35-40 cycles with annealing temperatures of 50-62° (see Suppl. material 1: Table S1 for details), a 1-minute extension at 72°, and a 5-minute final extension at 72°. Successful PCR products were sent to Macrogen USA (Rockville, MD) for Sanger sequencing in both directions. Sequence chromatograms were compiled, inspected, and preliminarily aligned in Geneious (Auckland, NZ).
Sequences of COI were length invariant, and alignment was trivial. Sequences of all other markers included length variation. These were aligned using MAFFT online (Katoh et al. 2017), using the 'Auto' setting, which selected an internal algorithm depending on number, length, and complexity of sequences. Combined sequences were analyzed under parsimony in PAUP* (Swofford 2002), with all sequences weighted equally, gaps treated as missing data, 100 random sequence addition replicates, saving no more than 1000 trees at each step; and under Bayesian criteria using Mr-Bayes (v.3.2.6 [Ronquist and Huelsenbeck 2003]) on the CIPRES Science Gateway, partitioning the four-gene data set, and implementing a GTR+I+Γ model; nruns=2, ngen=10,000,000, nchains=4, burninfrac=0.25.

Phylogeny
There is a high degree of molecular diversity and divergence among species and populations of Nearctic Eurhoptus. Uncorrected pairwise divergences in COI exceeded 10% between all of the species we recognize below (for which we had data). Some still contain intraspecific divergences approaching this. However, the higher divergences in these cases are spanned by intervening populations, and are united by morphology, and we do not yet see clear grounds for further separation.
Both parsimony and Bayesian analyses (see Figure 1) supported a deep primary division between E. pyriformis and three species very similar to and including E. sordidus, which exhibit a narrowed pronotal base. Preliminary morphological work suggested that 'E. pyriformis', as previously circumscribed (all those populations with a broad pronotal base), contained up to three species. One of these, referred to below as E. cariniventris n. sp., was not represented by molecular data, but appears justifiably distinct based on Figure 1. One of a number of equally parsimonious trees (numerous rearrangments within species were equally parsimonious). Numbers on branches represent Bayesian posterior probabilities >75% for major clades. Terminal units are named by DNA extraction code/voucher number, followed by state of collection (two letter abbreviation) and COI haplotype, as reported in Caterino and Langton-Myers (in press), or newly here. Dotted lines represent hypothetical placements of two other species, yet unsampled for DNA. male genitalia. Another morphotype, referred to in Caterino and Langton-Myers (in press) as 'patterned E. pyriformis' turns out to be neither genetically nor morphologically supportable. Individuals showing these distinctively patterned elytra (Figures 2A, B) are now known from across the range (specifically individuals from NC, GA, and AR), and these are resolved as paraphyletic with respect to a 'plain' morphotype. Genitalia are somewhat variable in both, particularly with regard to the shape of the aedeagal tip.
Morphological and molecular data agree in distinguishing multiple species within what has been referred to as E. sordidus. Eurhoptus sordidus itself is restricted to eastern Texas, western Arkansas, and eastern Oklahoma. Sequenced individuals from Arkansas and Texas are strongly supported as monophyletic, and minimally divergent among themselves. A largely more eastern lineage is strongly supported as the sister to E. sordidus, and for this we resurrect Hamilton's (1893) name E. curtus. There is some potentially interesting subdivision among E. curtus, particularly with regard to some southeasternmost representatives (South Carolina specimens from Greenville and McCormick Counties). However, molecular sampling across this widespread species' broad range is not yet adequate to assess variation patterns. A third species in the sordidus lineage is that which we describe below as E. aenigmaticus. This is restricted to a rather small area of southern Alabama, Mississippi, and Lousiana. The genitalia of this species is quite distinct. We've only been able to sequence DNA from Alabama specimens, and their monophyly is not well supported (probably because COI has only been sequenced for two of the four individuals). However, it appears to represent a sister to E. sordidus + E. curtus.
With regard to species not represented by molecular data, we would predict that E. cariniventris would be resolved as the sister to E. pyriformis. Eurhoptus occidentalis from west Texas appears morphologically close to E. sordidus, and would likely fall out somewhere in that clade. Eurhoptus imbricatus and E. rileyi would appear further from these other Nearctic species, and may represent one or more independent lineages with closer relationships to groups known from Mexico and southward. Much broader representation from this largely undescribed Neotropical fauna will be necessary before anything can be said about their relationships.  Redescription (U.S.A. species only). Small, convex, rounded, dull black or darkbrown. Body length (exclusive of head and rostrum) 1.8-3.2 mm, cuticle either largely bare, variously covered with short, fine to coarse, recurved seta-like scales, lacking other scales or variously clothed with dense approximate to imbricate flat scales in addition to recurved seta-like scales. Rostrum short, stout, flattened dorsally, about as long as prono-tum or slightly less, scaly towards base, glabrous, finely punctured towards apex in female, more coarsely so in male; medially carinate or not. Eyes small, flat, oval, largely covered by slight post-ocular lobes when rostrum in repose. Head with frons scaly, not impressed. Antennae red-brown, funicle of 7 desmomeres, club small, oval. Pronotum about as wide as long, lateral margins rounded or straight; if straight, then margins tapered more or less evenly from base to apex with greatest width at base; if rounded, then apical portion constricted, tubulate with greatest width before base. Basal margin nearly straight, disc variously punctured, medially carinate, sulcate or evenly punctured; post-ocular lobes slight. Elytra robust, strongly rounded dorsally and laterally, striae distinct, of small to very large punctures; all elytral intervals evenly elevated, slightly rounded, each with single row of recurved seta-like scales. Scutellar shield not visible. Mesoventral cup distinct, metaventrite short, medially impressed behind cup or carinate. Abdomen with ventrite 1 variously modified with large median or paired rather deep pits, pit either glabrous, shining or filled with erect scales; areas around pit often with dense, fine golden setae encircling depression; ventrite 5 broadly triangular, about as long as ventrites 2-4 combined. Legs with femora not toothed, narrow to stout (greatly so in some species where width accentuated by dense, erect scales along dorsal and lateral margins); tibiae narrow to stout (greatly so in some species where width accentuated by dense, erect scales along dorsal and lateral margins); tarsi fine, narrow, article 3 widest, bilobed; tarsal claws minute. Male with aedeagus short, one-half or less length of aedeagal apodemes, in lateral view very slightly curved ventrally to almost straight, in dorsal view with lateral margins subparallel, slightly to abruptly convergent towards apex at about apical one-third to one-fifth. Internal sac with apical sclerite complex of modified cruciform arrangement. Female with bursa copulatrix and vagina lacking any internal sclerotization, spermatheca L-shaped; distal gonocoxite elongate-triangular, with distinct long, slender apical stylus, sternite 8 with apical lamellae short, basally widely divergent, basal apodeme rather robust, elongate, expanded slightly at apex, tergite 8 tapered towards truncate or acuminate finely irregularly serrate apex.

Taxonomy
Diversity. For many years two species have been recorded as occurring in the eastern U.S.A., E. pyriformis and E. sordidus; however, specimens from central Texas of E. sordidus differed in the structure of ventrite 1 with two separate impressions and not a single larger impression thus suggesting a third species was present. This species and two additional undescribed species were noted by Anderson (2002).
Natural history. Almost all records of specimens of Eurhoptus are from sifting leaf litter in various forested habitats. Otherwise, nothing is known of life history and immature stages.  Notes about types. This species was described from a single specimen labelled "Ill[inois]". It has a red square label with "Type 5316" and a handwritten label "Eurhoptus pyriformis Lec.". It is not dissected but appears to be a male based on the more coarsely punctate rostral apex. The type was not examined although high resolution images posted on the MCZC Online Type Database (http://140.247.96.247/mcz/Species_record. php?id=5050) were examined. There is little doubt as to the identity of this species. Redescription. Body length (exclusive of head and rostrum) 2.1-2.9 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales, most specimens lacking other scales but some with head and base of rostrum scaly and with a few broad, flat pale imbricate scales variously arranged in irregular oblique band across elytra in apical one-half on intervals 2-7 and at bases of intervals 3-4 and 7. Pronotum with lateral margins straight, margins tapered more or less evenly from base to apex with greatest width at base, not medially carinate but may be medially impunctate in some specimens. Elytra strongly rounded dorsally and laterally, striae distinct, of large punctures, especially in posthumeral region; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially deeply impressed behind mesoventral cup. Abdomen with ventrite 1 with large median deep glabrous shining pit, area around pit with dense, fine golden inwardly directed scales encircling depression. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus about as long as one-half length of aedeagal apodemes, in lateral view slightly ventrally curved, in dorsal view with margins subparallel but abruptly strongly tapered towards apex at about apical one-quarter to one-fifth, apex produced medially as narrow extension, broadly rounded at tip, extension slightly narrower or more acuminate in some (scaly) specimens. Internal sac with large distinct cruciform apical sclerite complex, anterior bars longer than posterior bars, bars well defined, subparallel. Distribution ( Figure 3). This species is widely distributed in the eastern U.S.A. from Illinois, Pennsylvania and Michigan in the north, to the Gulf Coast of Mississippi and Louisiana in the south, and from Arkansas in the west, east to the Carolinas. Any literature records of this species from Texas are of E. cariniventris. Salsbury (2000) records a single specimen of this species from Kansas without further details; Ciegler (2010) records it from South Carolina. Blatchley and Leng (1916), followed by O' Brien and Wibmer (1982) include Colorado in the distribution but this seems in error.

Eurhoptus pyriformis
Notes about variation. Some specimens examined have a few broad, flat pale imbricate scales variously arranged in an irregular oblique band across the elytra in the apical one-half on intervals 2-7 and at bases of intervals 3-4 and 7 (Figures 2A-B). These specimens also possess a slightly narrowed apex of the aedeagus but otherwise do not seem to be different from unscaled specimens and the two forms appear to be broadly sympatric. Sequences available to date are predominantly from southern Appalachia, the majority of which represent the unscaled form ( Figures 2C-D). However, the scaled form is in fact more widespread, ranging from Arkansas in the west to South Carolina, and north to Michigan, and the molecular data suggest that this form is paraphyletic with respect to those unscaled populations in Appalachia. Similar scaling and the structure of abdominal ventrite 1 in E. cariniventris lead us to suggest its relationship as sister to E. pyriformis.
Specimens examined (  Notes about types. This species was described from a single specimen labelled "Tex". It has a rectangular label "776" and a red square label with "Type 5268" and a handwritten label "A. sordidus Lec.". It is not dissected but appears to be a male based on the more coarsely punctate rostral apex.  (Geiser 1933). We here apply the name E. sordidus to specimens from throughout Texas north into bordering Oklahoma and Arkansas, and east through Louisiana to Mississippi. The herein described new species and the resurrected species closely related to E. sordidus occur further to the east and not into Texas although the three are narrowly sympatric in Louisiana and Arkansas. Kissinger (1964) was the first to recognize this species as Eurhoptus. Redescription. Body length (exclusive of head and rostrum) 2.1-2.7 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales only, although often encrusted and coated with a fine film. Pronotum with lateral margins rounded, margins strongly constricted at about apical one-third such that apical one-third is distinctly tubulate, greatest width at about basal one-third, medially carinate or not. Elytra strongly rounded dorsally and laterally, striae distinct, punctures moderate in size and depth; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially impressed behind mesoventral cup. Abdomen with ventrite 1 with pair of obliquely arranged transversely elongate pits which are shallowly continuous medially (but because of encrustation appearing as separate in most specimens), area around pits with dense inwardly directed scales. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus about as long as one-half length of aedeagal apodemes, in lateral view slightly ventrally curved, in dorsal view with margins subparallel but gradually tapered towards apex at about apical one-third where more strongly tapered, apex not produced medially as narrow extension, broadly rounded at tip. Internal sac with large distinct cruciform apical sclerite complex, with well-defined transverse bar, anterior and posterior bars not well defined.
Distribution ( Figure 5). This species is distributed from Texas and Oklahoma east into Arkansas and Louisiana with a single outlying specimen from southern Missis-  Notes about types. This species was described from Pennsylvania from a series of 4 specimens (CMNH) of which we have selected one as lectotype. It is labelled with a handwritten label "Type", a second rectangular pink blank label, a third rectangular label "Carn. Mus. / Acc. 349", a fourth red square blank label and our lectotype des- ignation label. It is not dissected but appears to be a male based on sculpture of the rostral apex. This name has long been considered a junior synonym of E. sordidus but with the recognition of the latter species as distinct from specimens occurring further east and north, the oldest available name for these eastern forms becomes E. curtus. Redescription. Body length (exclusive of head and rostrum) 1.8-2.8 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales only, although often encrusted and coated with a fine film. Pronotum with lateral margins rounded, margins constricted at about apical one-third such that apical one-third is tubulate, greatest width at about basal one-third, medially carinate or not. Elytra strongly rounded dorsally and laterally, striae distinct, punctures moderate in size and depth; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially impressed behind mesoventral cup. Abdomen with ventrite 1 with pair of obliquely arranged transversely elongate pits which are continuous medially, area around pits with inwardly directed scales. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus about as long as one-half length of aedeagal apodemes or slightly shorter, in lateral view slightly ventrally curved, in dorsal view with margins very gradually tapered towards apex at about apical one-quarter to one-fifth where abruptly constricted, apex produced medially as broad lobe-like extension, broadly rounded at tip. Internal sac with large distinct cruciform apical sclerite complex, with well-defined posterior bars, anterior and transverse bars not well defined.

Eurhoptus curtus (Hamilton, 1893), resurrected name
Distribution (Figure 7). This species is widely distributed in the eastern U.S.A. from Illinois and Pennsylvania in the north, south nearly to the Gulf Coasts of Louisiana and Mississippi. Across this range it exhibits a high degree of intraspecific genetic variation, with some surprisingly well supported subclades, especially in a group of populations from central South Carolina (Greenville and McCormick Counties). However, most of the range of the species is sparsely represented in the sequence data set, and no further subdivision appears warranted.
Specimens examined ( Description. Body length (exclusive of head and rostrum) 2.3-3.0 mm, cuticle almost fully covered with broad, flat scales and scattered short, fine recurved (pronotum) to appressed (elytra) seta-like scales. Pronotum with lateral margins rounded, margins constricted at about apical one-third such that apical one-third is tubulate, greatest width at about basal one-third, not medially carinate; pale scales almost entirely covering pronotum to limited to midline and pair of lateral lines (giving some specimens a trivittate appearance). Elytra strongly rounded dorsally and laterally, striae distinct, of small punctures; all elytral intervals flat, each with single row of fine almost appressed seta-like scales; broad flat scales largely dark brown, approximate, scales pale and imbricate in an irregular oblique band across elytra in apical one-half, at bases of interval 3, at humeri and at elytral apex. Metaventrite medially impressed behind mesoventral cup. Abdomen with ventrite 1 with large median deep shining pit, base of pit with numerous erect, broad pale scales, scales somewhat condensed along midline in anterior portion of pit (giving a divided appearance); area around pit with dense, fine golden inwardly directed scales encircling depression. Legs with femora and tibiae fringed with dense erect scales along outer and inner margins, hind tibiae distinctly wider at about basal one-third. Aedeagus about as long as slightly less than one-half length of aedeagal apodemes, in lateral view slightly ventrally curved, in dorsal view with margins subparallel but gradually rounded towards apex at about apical one-quarter, apex produced medially as slight extension, broadly rounded at tip. Internal sac with apical sclerite complex with well-defined pair of hook-like sclerites.
Distribution (Figure 9). This species is distributed in the Edwards Plateau region of central Texas, east into Louisiana and southern Arkansas.
Etymology. We name this species "imbricatus" (L., an adjective or participle in the nominative singular, tiled, having adjacent edges overlapping) after the overlapping or imbricate scales of the oblique band on the elytra.
Variation. There is some variation in the extent of the distribution of pale scales on the pronotum. Description. Body length (exclusive of head and rostrum) 3.2 mm, cuticle almost fully covered with broad, flat scales and scattered short, broad recurved, seta-like scales. Pronotum with lateral margins rounded, margins strongly constricted at about apical one-third such that apical one-third is distinctly tubulate, greatest width at about basal one-third, medially sulcate, median line glabrous, impunctate. Elytra strongly rounded dorsally and laterally, striae distinct, of small punctures; all elytral intervals evenly elevated, slightly rounded, each with single row of broad recurved seta-like scales. Metaventrite medially slightly impressed behind mesoventral cup. Abdomen with ventrite 1 with large median deep glabrous shining pit, area around pit with  dense, fine golden inwardly directed scales encircling depression and entering pit along anteriorly along midline such that pit appears somewhat divided. Legs with femora and tibiae fringed with dense erect scales along outer and inner margins, hind tibiae distinctly wider at about midlength. Single specimen likely female, not dissected.
Distribution ( Figure 5). This species is known only from a single specimen collected in southern Texas. No records of the species from Mexico are known.
Etymology. We name this species after Edward G. Riley (retired) Description. Body length (exclusive of head and rostrum) 1.8-2.7 mm, cuticle largely bare, variously covered with dense, short, fine recurved seta-like scales only. Pronotum with lateral margins rounded, margins constricted at about apical one-third such that apical one-third is tubulate, greatest width at about basal one-third, not medially carinate. Elytra strongly rounded dorsally and laterally, striae distinct, punctures moderate in size and depth; all elytral intervals evenly elevated, slightly rounded, each with single row of dense, fine recurved seta-like scales. Metaventrite medially slightly impressed behind mesoventral cup. Abdomen with ventrite 1 with pair of obliquely arranged transversely elongate pits which are separate medially, and with second pair of small rounded pits along posterior margin of ventrite; ventrite 5 with small pair of central, rounded impressions. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus about as long as one-half length of aedeagal apodemes, in lateral view slightly ventrally curved, in dorsal view with margins gradually convergent from base to apex, apex not produced, broadly rounded. Internal sac with large distinct apical sclerite complex, with median pyriform sclerite, bordered laterally by pair of apically convergent longitudinal bars these each bordered posteriorly by well-defined transverse pyriform sclerite, longitudinal bars not well-defined.
Distribution (Map 2). This species is distributed in west Texas in the Guadalupe and Chisos Mountains. Despite extensive sampling, no specimens are known from New Mexico or Arizona. National Park, Window Trail, 1370m (29.275, -103.317), W. Suter, 29 May 19836, CWOB);Brewster Co.: Big Bend National Park, Window Trail, 1370m (29.275, -103.317), W. Suter, 27 August 1983Brewster Co.: Big Bend National Park, Basin Area, (29.27, -103.30), E.G. Riley, 20-21 July 2002, berlese oak ravine litter (10, EGRC; 23, TAMU); ); Brewster Co.: Big Bend National Park,Emory Peak Trail (29.26,), C.E. Carlton, 4 Aug 2000, berlese (2, LSAM);Culberson Co.: Guadalupe Mountains National Park, McKittrick Canyon (31.98, -104.78), P.W. Kovarik, 4 Sep 1986, leaf litter (2, CMNC). Description. Body length (exclusive of head and rostrum) 2.2-2.5 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales only, although often encrusted and coated with a fine film. Pronotum with lateral margins rounded, margins constricted at about apical one-third such that apical one-third is tubulate, greatest width at about basal one-third, medially carinate (most) or not (few). Elytra strongly rounded dorsally and laterally, striae distinct, punctures large in size, deep; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved setalike scales. Metaventrite medially deeply impressed behind mesoventral cup. Abdomen with ventrite 1 with pair of rounded pits which are continuous medially, area around pits with inwardly directed scales. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus slightly longer than one-half length of aedeagal apodemes, in lateral view very slightly ventrally curved, in dorsal view with margins gradually tapered towards very blunt, truncate apex, apex not produced medially. Internal sac with large distinct apical sclerite complex, with median pyriform sclerite, bordered laterally by pair of inwardly arcuate longitudinal bars these each bordered posteriorly by an elongate oblique sclerite. Distribution (Figure 13). This species is distributed in the southern coastal plain of the U.S.A. from Alabama and Florida west to Louisiana. We have been able to sequence KKV, CAD, and COI from some individuals from Alabama. In COI these are rather divergent, though the other two genes show minimal difference from Eurhoptus curtus. Further effort to obtain sequences from these and other populations of E. aenigmaticus will help support its placement relative to E. sordidus and E. curtus.

Eurhoptus aenigmaticus
Etymology. We name this species 'aenigmaticus' (L., an adjective or participle in the nominative singular, enigma, puzzle or riddle) after encountering difficulty in separating it from closely related species of the genus.  Description. Body length (exclusive of head and rostrum) 1.8-2.4 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales, most specimens lacking other scales but some with head and base of rostrum scaly and with a few broad, flat pale scales variously arranged on elytra in apical one-half and at bases of intervals 2-4. Pronotum with lateral margins straight, margins tapered more or less evenly from base to apex with greatest width at base, medially carinate or not. Elytra strongly rounded dorsally and laterally, almost globular, striae distinct, of very large punctures, especially in posthumeral region; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially distinctly carinate behind mesoventral cup. Abdomen with ventrite 1 with large median deep glabrous shining pit, area around pit with dense, fine golden inwardly directed scales encircling depression. Legs with femora and tibiae fringed with erect scales along outer margin of tibiae, hind tibiae subequal in width throughout most of length to slightly wider at basal one-third. Aedeagus about as long as one third length of aedeagal apodemes, in lateral view almost straight, in dorsal view with margins subparallel but strongly tapered towards apex at about midlength, apex produced medially as fine acuminate point. Internal sac with distinct apical sclerite complex of pair of longitudinal parallel bars. Distribution (Figure 9). This species is distributed throughout central Texas and appears to be disjunct to the panhandle of Florida and adjacent Alabama and Georgia. All published Texas records of E. pyriformis are this species.
Etymology. We name this species "cariniventris" (L., an adjective or participle in the nominative singular, carina, keeled, and ventris, belly) after the distinctly carinate metaventrite posterior to the mesoventral cup. Variation. This species appears to have two disjunct portions of its range; central Texas and Florida panhandle and adjacent Alabama into eastern Georgia. We know of no specimens from the intervening areas. Specimens from Florida/Alabama have larger, deeper elytral punctures (especially in the posthumeral area) but have similar male genitalia and do not differ in other structural characters. At present, we consider these eastern specimens to be conspecific with the Texas specimens but have excluded them from the type series.  Body surface almost fully densely covered with broad flat scales, elytra with an irregular oblique band of lighter scales across elytra in apical one-half (Figures 8, 10). Legs with femora and tibiae fringed with dense erect scales on both inner and outer margins, hind tibiae with width distinctly greatest at basal one-third of length or at midlength . Pronotum with lateral margins more or less uniformly convergent from base to apex (e.g. Figure 2A), greatest width at base. Abdomen with ventrite 1 with single large cavernous, shining median pit ( Figure 2E Metaventral midline raised and carinate ( Figure 14C). Elytra with scales of intervals fine, narrow. Many specimens with elytral punctures large and pitlike in area behind humeri ( Figure 14B). Aedeagus as in Figures 14D-E  Metaventral midline impressed, not raised. Elytra with scales of intervals slightly broader but narrow. Most specimens with elytral punctures slightly larger in area behind humeri but not large and pit-like ( Figure 2B). Aedeagus as in Figures 2F-H  Abdomen with ventrite 1 with four distinct impressions (2 anteriorly, 2 posteriorly; Figure 11C). Aedeagus as in Figures 11D-E  Aedeagus as in Figures