On Neotropical Merophysiinae with descriptions of a new genus and new species (Coleoptera, Endomychidae)

Abstract Intensive survey of museum collections and new field collecting resulted in discovery of six new, closely related species of the Neotropical Merophysiinae. A new species of the genus Lycoperdinella Champion, L. boliviensis sp. n., from Bolivia and Brazil, and five new species from Mexico for which a new genus is proposed here as Rueckeria gen. n.: R. inecol (type species), R. nigrileonis, R. ocelotl, R. puma, R. skelleyi spp. n., have been discovered. Lycoperdinella, Rueckeria gen. n., L. subcaeca Champion and all new species are diagnosed, described, and illustrated. Keys to the species of Lycoperdinella and Rueckeria and a distribution map are provided. A lectotype of Lycoperdinella subcaeca Champion, 1913 is designated. Molecular barcodes of three new species of Rueckeria are provided in order to help with the identification of these taxa.


Introduction
Merophysiinae is a subfamily of Endomychidae, a moderately large family of mycophagous beetles distributed worldwide but with highest diversity in the tropical regions (Shockley et al. 2009a, b). The family, historically classified in the superfamily Cucujoidea (e.g., Lawrence and Newton 1995, Tomaszewska 2000, 2010, Shockley et al. 2009a) has recently been redefined by the exclusion of former subfamilies Eupsilobiinae, Mycetaeinae, and Anamorphinae which have been elevated to the level of independent families, all classified now in the superfamily Coccinelloidea (Robertson et al. 2015).
Merophysiinae (= Holoparamecinae) (Tomaszewska 2000(Tomaszewska , 2005 comprise 12 genera and more than 100 species (Shockley et al. 2009a) with most species diversity in the Old World. Merophysiines are usually small in size, ranging from one to three millimeters. The group is well supported morphologically by having the tentorium without a corpotentorium, labial palpomere 2 oval and inflated, and larval head lacking stemmata (Tomaszewska 2000(Tomaszewska , 2005. Molecular study (Robertson et al. 2015) also supports monophyly of this subfamily.
The Neotropical region is inhabited by five merophysiine genera. Holoparamecus Curtis, 1833, including numerous species distributed worldwide, and four genera endemic to the Neotropics: Colovocerida Belon, 1884, Lycoperdinella Champion, 1913, Pseudevolocera Champion, 1913and Pseudoparamecus Brèthes, 1922. However, apart from the often studied and well known Holoparamecus, and carefully studied (during preparation of this paper) type material of monotypic Lycoperdinella, the remaining three genera are rather enigmatic. Pseudevolocera was described as having a 10-segmented antenna with 3-segmented club, prosternum having large fossae for the reception of antennal club, pronotum with basal groove but without foveae, tarsi 3-segmented, metaventral postcoxal lines, and weak abdominal lines present. Champion (1913) himself suggested close relationships between Pseudevolocera and Evolocera (which is a member of the family Eupsilobiidae). Colovocerida, as described by Belon (1884), has an 11-segmented antenna with 2-segmented club, 4-segmented tarsi with tarsomere 3 shortened, and abdominal ventrite 1 with postcoxal lines. Finally, Pseudoparamecus, according to Brèthes (1922) has a 10-segmented antenna with 3-segmented club, front and hind coxae subcontiguous, and mid coxae contiguous. From the original descriptions of these genera (diagnostic combination of characters) it seems that they doubtedly belong to Merophysiinae or even to any other Endomychidae subfamily. Their taxonomic position needs further study.
In addition to the information about the introduced species of Holoparamecus, which probably feed on the molds of stored grains (Shockley et al. 2009b), almost nothing is known about the biology of the neotropical species of Merophysiinae. The most noteworthy exception is Holoparamecus gabrielae Rücker which was collected in a pile of bat guano in a cave of central Veracruz, Mexico (Rücker 2003). The gut content of a new species of Lycoperdinella described here shows fragments of phragmospores, suggesting that it probably feeds on Ascomycetes fungi. logical structures were taken using a Canon EOS 1100D digital camera attached to an Olympus BX41 compound microscope and subsequently combined using Helicon Focus software. Scanning electron micrographs were taken using a Hitachi S-3700N environmental electron microscope at the Department of Palaeontology, National Museum in Prague and a HITACHI S-3400N microscope (www.hitachi.com) in the Electron Microscopy Laboratory at the Museum and Institute of Zoology, Polish Academy of Sciences in Warsaw.
The species descriptions of Lycoperdinella start from the type species and follow by a new species; the species of Rueckeria gen. n., are ordered alphabetically.
The beetle-specific terminology and numbering of body parts follow Lawrence et al. (2011). Classification follow Tomaszewska (2010).
Distribution. Central and South America: Bolivia, Brazil, Costa Rica, Guatemala (Fig. 21). Figs 2,5,21 Lycoperdinella subcaeca Champion, 1913: 115. Type locality: Guatemala. -Shockley et al. 2009aRobertson et al. 2015: 766. Differential diagnosis. Lycoperdinella subcaeca is similar to L. boliviensis in its body shape, color and vestiture, however L. subcaeca can be separated from that species by having the pronotum more elongate (0.80 times as long as broad), eyes reduced to six facets only (in both type specimens studied), mentum somewhat pentagonal (sharply produced anteriorly in the middle of apical margin), the abdominal ventrite 1 longer than the mesoventrite and the hind wings absent. Redescription. Length 1.39 mm, width 0.66 mm, height 0.47 mm; body elongate-oval, moderately convex, 2.11 times as long as wide, 2.96 times as long as high 4a,b). Surfaces shiny; sparsely covered with long, decumbent, golden setae. Color homogeneously reddish brown.

Lycoperdinella subcaeca Champion
Head with interocular distance 0.83 times as wide as head including eyes. Eyes very small, composed of six facets (Fig. 5a). Antenna rather short and slender (Fig. 5c), 0.83 times as long as head and pronotum combined; scape 1.52 times longer than wide, 1.09 times as long as pedicel; pedicel 1.88 times longer than wide; antennomere 3, 1.50 times longer than wide, 0.66 times as long as pedicel; antennomeres 4-8 getting very gradually shorter and wider towards antennomere 9, which is 0.98 times wider than long and 0.64 times as long as pedicel; terminal antennomere inflated, asymmetrical, 2.03 times as long at longer margin than pedicel, its longest margin 1.30 times longer than shorter lateral one and 1.18 times as long as apical margin; apical margin truncate. Mentum subquadrate with lateral margins weakly rounded and anterior margin sharply produced anteriorly at mid-line (Fig. 5a).
Pronotum weakly transverse (Fig. 5b), 0.80 times as long as wide, 1.50 times wider than head, 1.06 times wider at widest part than at base, widest at about anterior third, weakly convex; front angles very weakly produced, rounded, lateral margins almost rounded in anterior third, then converging to posterior angles, comparatively widely bordered with edges distinctly crenulate; hind angles weakly obtuse, rounded at tips. Posterior half of disc with a vaguely defined triangular impression. Longitudinal sulci distinctly convergent anteriorly, extending from base to almost half length of pronotum; well defined transverse sulcus connecting deep pores and weakly marked basal transverse depression provided with large punctures (Fig. 5e); area between transverse sulci/depressions weakly convex; posterior margin weakly lobed at mid-line. Prosternal process widely separates front coxae, widest at mid length.
Elytra 0.94 mm long, 1.42 times longer than wide; 2.19 times as long as and 1.22 times as wide as pronotum; widest at basal fourth then continuously distinctly converging to rounded apex; with hooked tooth present anterolateral corner. Hind wings absent.
Legs moderately long. Femora very narrow at base, strongly widened at apical half. Tibiae narrow, straight, continuously widened towards their apices. Metatibia very narrow, 0.34 times as long as elytra. Metatarsus moderately long, 0.6 times as long as metatibia.
Male unknown. Comments. This species was listed by Shockley et al. (2009a) as present also in Costa Rica. However, due to a lack of any specimens accessible for examination from this country during our extensive study, a question mark is added in the distribution map for this species in Costa Rica. Champion (1913) clearly indicated that his original description of L. subcaeca was based on two specimens from Guatemala. One left in 'U.S. Nat. Mus.' and the second specimen was 'presented to the British Museum'. As the lectotype we have chosen and designated a specimen available for direct study (borrowed to WT from the NHM). The syntype from USNM, examined on photos becomes a paralectotype.
Differential diagnosis. Lycoperdinella boliviensis closely resembles L. subcaeca in its overall body shape, color and vestiture, but can be separated from L. subcaeca by having the pronotum more transverse (0.68-0.70 times as long as broad), eyes composed of 36 facets (based on studied specimens), mentum subrectangular with its anterior margin weakly arcuate, and the abdominal ventrite 1 shorter than the mesoventrite, and by the presence of well-developed hind wings.
Head with interocular distance 0.75 times as wide as head including eyes ( Fig. 6a, b). Eyes small, composed of 36 facets. Antenna rather short and slender (Fig. 1e), 0.72 times as long as head and pronotum combined; scape 1.33 times longer than wide, 1.15 times as long as pedicel; pedicel 1.15 times longer than wide; third antennomere 1.15 times longer than wide, 0.65 times as long as pedicel; antennomeres 4-8 getting very gradually shorter and wider towards antennomere 9 which is 1.28 times wider than long and 0.6 times as long as pedicel; terminal antennomere inflated, asymmetrical, 2.30 times as long at longer margin than pedicel, its longest margin 1.16 times longer than shorter lateral one, and 1.16 as long as apical margin, apical margin truncate. Mentum subquadrate, with lateral margins weakly rounded and anterior margin slightly arcuate (Fig. 6b). Pronotum weakly transverse (Fig. 6c), 0.68-0.70 times as long as wide, 1.53-1.57 times wider than head, about 1.05 times wider at widest part than at base, widest at about mid length, weakly convex; front angles weakly produced, rounded, lateral margins almost continuously rounded, subparallel to weakly sinuate in basal fifth, comparatively widely bordered with edges distinctly crenulate; hind angles right-angled to weakly obtuse, rounded at tips. Anterior half of disc with a vaguely defined longitudinal impression. Longitudinal lateral sulci distinctly convergent anteriorly, reaching anteriorly beyond half-length of pronotum; well defined transversal sulcus connecting deep pores; area between transverse sulcus and basal, shallow depression/sulcus weakly convex, with a guitar-shaped shallow, median depression; posterior margin distinctly lobed at mid-line. Prosternal process widely separates front coxae, widest at mid length (Fig. 6e).   Elytra 0.82-0.88 mm long, 1.38-1.45 times longer than wide; 2.60-2.70 times as long as and 1.25 times as wide as pronotum; widest at basal fourth then continuously distinctly converging to rounded apex; with hooked tooth present at anterolateral corner. Punctation composed of small setiferous punctures, and sparse larger, shallow foveate punctures (Fig. 6d). Hind wings well developed, 1.3 times longer than elytra.
Legs moderately long. Femora very narrow at base, strongly widened at apical half. Tibiae narrow, straight, continuously widened towards their apices. Metatibiae very narrow, 0.35 times as long as elytra. Metatarsus moderately long, 0.55 times as long as metatibia.
Abdomen with ventrite 1 slightly shorter than metaventrite and as long as three following ventrites combined (Fig. 6f ). Ventrite 5 arcuate at apex.
Female genitalia with long, narrow coxites, emarginate at their apices, styli indistinct; spermatheca with one chamber rounded and second irregularly long oval; sperm duct moderately long, accessory gland elongate oval (Fig. 3d, e).
Male unknown. Distribution. South America: Bolivia (Cochabamba), Brazil (Manaus) (Fig. 21). Comment. Robertson et al. (2015) included in their molecular analysis one specimen from Bolivia, Santa Cruz province, identified as Lycoperdinella subcaeca. However, we have studied pictures of the disarticulated voucher and concluded that it certainly does not belong to that species. Most likely it is a member of L. boliviensis n. sp.

Key to species of Lycoperdinella
Etymology. This genus is dedicated to Dr. Wolfgang Rücker, German coleopterist, who has devoted many years of his life to the study of merophysiine beetles.
Distribution. Mexico: Hidalgo, Querétaro, Veracruz (Fig. 21). Etymology. The name of the new species is dedicated to our colleagues in INECOL (The Institute of Ecology, Xalapa, Mexico), institution where the project within most specimens of this species were collected was held. Noun in apposition. Differential diagnosis. Rueckeria inecol is similar to R. skelleyi and R. ocelotl spp. n., by having the body completely brown and the abdominal ventrite 1 with irregularly rounded postcoxal lines (Fig. 16f ). However, it can be distinguished by the basal pronotal pores present (Fig. 16c) (not perforated in R. skelleyi), mentum subquadrate ( Fig. 16b) and pronotal lateral margins nearly smooth (Fig. 16c) (mentum subhexagonal and pronotal margins weakly crenulate in R. ocelotl), and by the features of the aedeagus (Fig. 8d-f ), with the tegmen about as long as the median lobe, with the sides parallel, and the median lobe widening apically.

Rueckeria inecol
Description. Length 1.90-2.17 mm, width 1.00-1.05 mm, height 0.62-0.67 mm; body elongate-oval, weakly convex, 2.07-2.34 times as long as wide, 3.32-3.36 time as long as high (Figs 8a-c, 13a, b). Surfaces shiny; sparsely covered with short, decumbent golden setae. Color reddish brown with yellowish brown antennae and legs. Head with interocular distance 0.77 times as wide as head including eyes (Fig. 16a,  b). Eyes small, composed of 16 facets. Antenna moderately long and slender (Fig. 7e), 0.86 times as long as head and pronotum combined; scape as long as wide, 1.7 times as long as pedicel; pedicel 1.8 times longer than wide; antennomeres 3-5, each 1.42 times as long as wide, 0.7 times as long as pedicel; antennomeres 6-8, 1.2 times as long as wide and 0.5 times as long as pedicel; antennomere 9, 1.33 times as long as wide, 0.55 times as long as pedicel; terminal antennomere inflated, asymmetrical, 2.2 times longer at longer margin than pedicel, longer margin 1.28 times as long as lateral one, apical margin concave. Mentum subquadrate, with straight anterior margin (Fig. 16b).
Legs moderately long. Femora very narrow at base, then strongly widened at apical half. Tibiae moderately narrow, continuously widening to apex. Metatibia very narrow, continuously widening apically, 0.31-0.36 times as long as elytra; metatarsus long, 0.66 times as long as metatibia.
Female genitalia with narrow coxites, with moderately large styli bearing two apical setae; spermatheca elongate (Fig. 8g). DNA barcode. GenBank accession number: MG676234 Etymology. The name of this new species is dedicated to our coleopterist colleagues in the National Collection of Insects in UNAM (National Autonomous University of Mexico) whose mascot is the puma, the pan-American felid.
Differential diagnosis. Rueckeria puma is most similar to R. nigrileonis by its small size, black body with yellow legs, antennae, and mouth parts (Fig. 11a-c); however, it can be distinguished by the pronotum more narrowed at base (1.20 times as wide at widest part than at base), abdominal postcoxal lines irregularly rounded and deeper reaching about half length of the ventrite 1 (Fig. 18g), and the aedeagus with the tegmen longer than the median lobe with the apex acuminate and the median lobe strongly widened at base and curved (Fig. 11d-f ).
Head with interocular distance 0.8 times as wide as head including eyes (Fig. 19a). Eyes small, composed of 18 facets. Antenna moderately long and slender (Fig. 19c), 0.85 times as long as head and pronotum combined; scape 1.30 times longer than wide, as long as pedicel; pedicel 1.55 times longer than wide; third antennomere 1.58 times longer than wide, subequal in length with pedicel; antennomeres 4-8 getting gradually shorter and wider towards antennomere 9 which is as long as wide and 0.5 times longer than pedicel; terminal antennomere inflated, asymmetrical, 2.5 times as long at longer margin as pedicel, its longer margin 1.22 times longer than lateral one and 1.4 times longer than apical margin, apical margin truncate. Mentum rectangular (Fig. 19b), weakly produced anteriorly in middle of apical margin.
Pronotum weakly transverse (Fig. 19e), 0.78 times as long as wide, 1.38 times wider than head, approx. 1.2 times wider at widest part than at base, widest at anterior fourth, strongly convex in mid length; front angles rounded, weakly produced, margins slightly sinuate, narrowing at basal third, narrowly bordered with edges very weakly crenulate; hind angles right-angled to weakly obtuse, rounded at tips. Anterior half of disc without impressions. Longitudinal sulci weakly convergent, reaching nearly anterior 2/5 of pronotum; basal lateral pores present, connected by deep, faintly defined transversal sulcus; posterior transverse sulcus provided with large foveate punctures, area between transverse sulci convex, weakly depressed at mid-line; posterior margin weakly lobed at mid-line. Prosternal process widely separates front coxae (Fig. 19f ), widest at mid length.
Legs moderately long. Femora very narrow at base, strongly widened at apical half. Pro-and mesotibiae very narrow, protibiae weakly sinuate, slightly widened towards apex. Metatibia very narrow, almost straight, continuously widening apically, more accentuated at apical fifth, slightly bent inwards in apical 2/3, 0.39-0.40 times as long as elytra. Metatarsus long, 0.65 times as long as metatibia.
Male genital segment with sternite emarginate apically, and acuminately rounded at its base. Tegmen large, sinuate in lateral view, with rugose and distinctly acuminate apex. Median lobe short, strongly widened at base, markedly curved, continuously strongly narrowing to acute apex. Tegminal strut absent (Fig. 11d-f ).
Female genitalia (Fig. 11g) with moderately broad coxites, and with large, elongate styli bearing two apical setae; spermatheca oval. Etymology. This new species is dedicated to our coleopterist colleagues in the entomological collection of the University of Guadalajara, whose mascot is a black lion. The name is derived from Latin "niger" (black) and "leo" (lion). Differential diagnosis. Rueckeria nigrileonis is most similar to R. puma by its small size and black body with legs, antennae and mouth parts yellow (Fig. 9a-c). However it can be distinguished by the pronotum being less narrowed at base (1.05 times wider at widest part than at base) (Fig. 17b), abdominal postcoxal lines regularly rounded, shallower, reaching about 1/3 length of ventrite 1, and the aedeagus with the tegmen longer than the median lobe with apex rounded and the median lobe moderately widened at base and curved (Fig. 9d-f ).
Head with interocular distance 0.8 times as wide as head including eyes. Eyes small, composed of 18 facets. Antenna moderately long and slender, 0.85 times as long as head and pronotum combined; scape 1.33 times longer than wide, 1.33 times as long as pedicel; pedicel 1.36 times longer than wide; third antennomere 1.66 times longer than wide, equal in length with pedicel; antennomeres 4-8 getting gradually shorter and wider towards antennomere 9 which is as long as wide and 0.7 times longer than pedicel; terminal antennomere inflated, asymmetrical, 2.25 times as long at longer margin as pedicel, its longer margin 1.45 times longer than lateral one and 1.05 as long as apical margin, apical margin truncate. Mentum subquadrate, weakly produced anteriorly in middle of anterior margin (Fig. 17a).
Pronotum weakly transverse (Fig. 17b), 0.75-0.80 times as long as wide, 1.41 times wider than head, 1.05 times wider at widest part than at base, widest at anterior fourth, strongly convex in mid length; front angles rounded, weakly produced; lateral margins slightly sinuate, narrowing at basal third, narrowly bordered with edges very weakly crenulate; hind angles right-angled to weakly obtuse, rounded at tips. Anterior half of disc without impressions. Longitudinal sulci weakly convergent, reaching nearly half length of pronotum; basal lateral pores present, connected by deep, faintly defined transversal sulcus; posterior transverse sulcus provided with large foveate punctures, area between transverse sulci convex, weakly depressed at mid-line; posterior margin weakly lobed at mid-line. Prosternal process widely separates front coxae, widest at mid length (Fig. 17e). Elytra 0.80-0.88 mm long, 1.18-1.24 times longer than wide; 2.10-2.20 times as long and 1.31-1.38 times as wide as pronotum; widest at basal fourth then continuously strongly converging to rounded apex. Punctation composed of small setiferous punctures, each accompanied posteriorly by 2-3 slightly larger shallow foveate punctures (Fig. 17c).
Legs moderately long. Femora very narrow at base, strongly widened at apical half. Pro-and mesotibiae very narrow, slightly curved inwards, parallel sided along basal 2/3, then widened towards apex. Metatibia very narrow, almost straight, continuously widening apically, more accentuated at apical fifth, 0.38-0.42 times as long as elytra. Metatarsus long, 0.68 times as long as metatibia.

Rueckeria skelleyi sp. n.
http://zoobank.org/DB845616-B120-457B- 13c,d,20 Etymology. The name of the new species is dedicated to our colleague Dr. Paul Skelley, the curator of the entomology collection in FSCA, where the holotype of this species was found during a visit of EA-V and WT in this collection. Differential diagnosis. Rueckeria skelleyi is similar to R. inecol and R. ocelotl spp. n, by the body completely brown and the abdominal ventrite 1 with irregularly rounded postcoxal lines. However it can be distinguished by the basal lateral pores not perforated as in the other species (Fig. 20c), mentum subrectangular and pronotal lateral margins smooth (Fig. 20c) (mentum subhexagonal and pronotal margins weakly crenulate in R. ocelotl), and by the features of the aedeagus (Fig. 12d-f ): tegmen markedly longer than the median lobe which is widened at base and provided with an additional acute process ventrally.
Description. Length 1.50 mm, width 0.64 mm, height 0.43 mm; body elongateoval, weakly convex, 2.35 times as long as wide, 3.32-3.50 times as long as high 13c,d). Surfaces shiny, sparsely covered by short, decumbent golden setae. Color reddish brown with yellowish brown antennae and legs. Head with interocular distance 0.80 times as wide as the head including eyes. Eyes small, composed of approximately 16 facets. Antenna moderately long and slender, 0.75 times as long as the head and pronotum combined; scape 1.20 times as long as wide, 1.16 times as long as pedicel; pedicel 1.5 times longer than wide; third antennomere 1.8 times as long as wide, 0.83 times as long as pedicel; antennomeres 4-7, 1.4 times as long as wide and 0.5 times as long as pedicel; antennomeres 8-9 as long as wide, 0.7 times as long as pedicel; terminal antennomere inflated, asymmetrical, 3.0 times longer at longer margin than pedicel, longer margin 1.32 times longer than lateral one, apical margin truncate. Mentum subquadrate, very weakly produced anteriorly in middle of anterior margin (Fig. 20a). Pronotum weakly transverse (Fig. 20a), 0.76 times as long as wide, 1.4 times as wide as head, 1.07 times wider at widest part than at base, widest at anterior fourth, rather convex at mid length; front angles rounded, weakly produced, margins slightly sinuate, narrowing at basal third; margins narrowly bordered, weakly crenulate; hind angles right-angled (Fig. 20c), rounded at tips. Anterior half of disc without impressions. Longitudinal sulci weakly convergent, almost reaching apical 2/5; basal lateral pores not perforated (Fig. 20c), just present as shallow depressions conected by moderately deep, faintly defined transversal sulcus, posterior transverse sulcus shallow provided with large foveate punctures; area between transverse sulci convex. Prosternal process moderately widely separates front coxae, weakly widening posteriad, its apical width 0.75 times the length of procoxae (Fig. 20d).
Elytra 0.85 mm long, 1.40 times as long as wide; 2.43 times as long and 1.34 times as wide as pronotum; widest at basal fourth then continuously strongly converging to rounded apex. Punctation composed of small setiferous punctures and dispersed, slightly larger, shallow foveate punctures.
Legs moderately long. Femora very narrow at base, then strongly widened at apical half. Tibiae moderately narrow, continuously widening to apex. Metatibia very narrow, straight, continuously widening apically, 0.31-0.36 times as long as elytra; metatarsus very long, 0.66 times as long as metatibia.
Abdomen with ventrite 1 slightly shorter than metaventrite and almost as long as three following ventrites combined; postcoxal lines on ventrite 1 reaching about half length of ventrite, irregularly rounded. Ventrite 5 arcuate apically.
Male genital segment with sternite rounded apically, basal margin acuminately rounded. Tegmen large, distinctly longer than median lobe, parallel sided, weakly curved in lateral view, apex rounded; tegminal strut indistinct. Median lobe widened and with additional acute ventral process near base, then strongly narrowing to markedly acute apex (Fig. 12d-f ). DNA barcode. GenBank accession number: MG676233 Etymology. The name is derived from the Nahuatl word for jaguar, inspired by the rosette-like pattern that can be seen on the elytra under certain type of light, caused probably by different densities of the chitin. A noun in apposition.
Differential diagnosis. Rueckeria ocelotl is similar to R. inecol and R. skelleyi spp. n, by the body completely brown and the abdominal ventrite 1 with irregularly rounded postcoxal lines (Fig. 18g). However, it can be distinguished by the pronotum with basal lateral pores present (not perforated in R. skelleyi), mentum subhexagonal (Fig. 18a) and pronotal lateral margins weakly crenulate (mentum subrectangular and pronotal margins smooth in R. inecol) and by the features of the aedeagus: tegmen distinctly shorter than median lobe, widened apically, median lobe subparallel-sided with moderately acuminate apex ( Fig. 10d-f ).
Head with interocular distance 0.75 times as wide as head including eyes. Eyes small, composed of approximately 16 facets (Fig. 18a). Antenna moderately long and slender (Fig. 18c), 0.78 times as long as head and pronotum combined; scape as long as wide, 0.8 times as long as pedicel; pedicel 2.0 times longer than wide; third antennomere 2.3 times as long as wide, 0.7 times as long as pedicel, antennomeres 4-5, 1.8 times as long as wide, 0.6 times as long as pedicel; antennomeres 6-8, 1.5 times as long as wide and 0.5 times as long as the pedicel; ninth antennomere 1.6 times as long as wide, 0.5 times as long as pedicel; terminal antennomere inflated, asymmetrical, 2.4     times longer at longer margin than pedicel, longer margin 1.4 times longer than lateral one, apical margin concave.
Pronotum weakly transverse, 0.77-0.80 times as long as wide (Fig. 18b), 1.51 times as wide as head, 1.09-1.14 times wider at widest part than at base, widest at anterior fourth, rather convex at mid length; front angles rounded, not conspicuously produced, margins slightly sinuate at anterior half, continuously narrowing to base; narrowly bordered, edges weakly crenulate (Fig. 18d); hind angles right-angled, rounded at tips. Anterior half of disc without impressions. Longitudinal sulci convergent, reaching apical 2/5; basal lateral pores present, connected by deep, faintly defined transversal sulcus, with additional posterior, transverse sulcus provided with large foveate punctures; area between transverse sulci convex. Prosternal process moderately widely separates front coxae, weakly widening posteriad, its apical width 0.85 times the length of procoxae. Mentum subhexagonal, with lateral margins angulate at mid-length, anterior margin straight (Fig. 18a). Elytra 1.15-1.18 mm long, 1.38-1.43 times as long as wide; 2.25-2.30 times as long as and 1.26-1.30 times as wide as pronotum; widest at basal fourth then continuously strongly converging to rounded apex. Punctation composed of small setiferous punctures and widely spaced, slightly larger, shallow foveate punctures (Fig. 18e).
Legs moderately long. Femora very narrow at base, then strongly widened at apical half. Tibiae moderately narrow, straight sided, continuously widening to apex. Metatibia very narrow, straight, continuous widening apically, 0.35-0.37 times as long as elytra; metatarsus 0.66 times as long as metatibia.
Abdomen with ventrite 1 slightly shorter than metaventrite and almost as long as three following ventrites combined; postcoxal lines on ventrite 1 shallow, nearly reaching 2/5 length of ventrite, irregularly rounded.
Male genital segment with sternite emarginate apically, and strongly acuminate at its base. Tegmen shorter than median lobe, narrower at basal third, then widening towards apex, with long setae on apical margin. Median lobe cylindrical, weakly curved in lateral view, narrowing near moderately acuminate apex (Fig. 10d-f ).

Discussion
The findings presented in this work reveal that the merophysiine fauna in the Neotropics is very poorly known. As a result, its diversity has been highly underestimated, while some monotypic genera considered as part of the subfamily were never re-examined and are most likely misclassified. This situation is caused in part to the lack of interest in studying small-sized beetles associated with environments such as forest leaf litter. Recent effort on studying the leaf-litter dwelling beetles from the cloud forests of Mexico revealed an unexpected diversity of merophysiine representatives that did not completely fit in the current generic concepts available. For those species a new genus, Rueckeria, is established here. Its members are evidently closely related to Lyco-perdinella, a genus that was previously considered as monotypic. The distribution of Lycoperdinella is greatly expanded, from Guatemala and Costa Rica where it was previously recorded to Bolivia and Brazil. In contrast to Lycoperdinella, where species seem to be broadly distributed, representatives of Rueckeria probably occur locally and have higher speciation-rate caused by the lack of flying ability. So far Rueckeria is known only from Mexican biogeographical provinces: Trans-Mexican Volcanic Belt and Sierra Madre Oriental. However, it cannot be stated that its distribution is restricted to these provinces. Additional collecting efforts will likely result in new discoveries at the specific level and could provide more DNA-grade specimens that will help us testing the monophyly of the genera. In parallel, the type specimens of the enigmatic genera Colovocerida Belon, Pseudevolocera Champion, and Pseudoparamecus Brèthes, must be studied in order to elucidate their systematic position.