Introduction
Epipocus Germar (Coleoptera: Endomychidae) is a genus of mycophagous beetles placed in the subfamily Epipocinae of the family Endomychidae. Epipocinae is restricted to the New World and is comprised of four genera presently: Anidrytus Gerstaecker, Ephebus Gerstaecker, Epipocus, and Epopterus Chevrolat. Tomaszewska (Reference Tomaszewska2000) proposed the male genital segment with lateral edges deeply and asymmetrically curved inwardly as a synapomorphy uniting members of this subfamily. Epipocus is easily diagnosed from the remaining genera by the following combination of characters: (1) antenna with the third antennomere two times longer than the fourth, (2) labial terminal palpomere weakly oval, moderately truncate apically, and (3) aedeagus with long and slender lateral ramus on left side in ventral view.
Before this work, Epipocus included 32 species and four subspecies ranging from the southern United States of America to Colombia, with greatest diversity in Mexico (Arriaga-Varela et al. Reference Arriaga–Varela, Tomaszewska and Navarrete–Heredia2007; Shockley et al. Reference Shockley, Tomaszewska and McHugh2009a). As with most members of Endomychidae, Epipocus species feed on hyphae and spores of a variety of fungi (Shockley et al. Reference Shockley, Tomaszewska and McHugh2009b). Specimens have been collected in association with basidiocarps of various families, for example, Boletaceae, Auriculariaceae, Polyporaceae, as well as on dead logs and under bark (Arriaga-Varela et al. Reference Arriaga–Varela, Tomaszewska and Navarrete–Heredia2007).
The most recent revision of Epipocus was published by Strohecker (Reference Shockley and Vandenberg1977). Therein, he proposed a division of the genus, for practical purposes, into four species groups based primarily on colour: (I) the E. longicornis group – species brown dorsally and ventrally, pronotum with or without black spots; (II) the E. tibialis group – species with pronotum red-brown, elytra black margined with red; (III) the E. sallaei group – species black dorsally, pronotal and elytral margins red; and (IV) the E. rufitarsis group – species entirely black, although tarsi and last two antennomeres may be lighter in colour.
Of the four species groups proposed by Strohecker, the E. rufitarsis group (group IV) is the most diverse, with 13 species and four subspecies distributed from central Veracruz, Mexico to Colombia. Some species of this group show a reduction of the wings, a feature to which Strohecker (Reference Shockley and Vandenberg1977) attributed the existence of many local “races”.
Herein, we add two species from Mexico and Costa Rica, which belong to the E. rufitarsis group. One species was found during preparation of a synopsis of Mexican Endomychidae (Arriaga-Varela et al. Reference Arriaga–Varela, Tomaszewska and Navarrete–Heredia2007). An interesting additional female specimen from Costa Rica clearly belonging to an undescribed species was found among material deposited in the INBio collection. Although this specimen shares the colour pattern of species assigned to Strohecker’s E. rufitarsis group, it displays a suite of characters that suggests it may represent a different lineage within Epipocus, calling into question the reliability of the colour-based species groups proposed by Strohecker (Reference Shockley and Vandenberg1977).
Materials and methods
This work is based on examination of specimens deposited in the following collections, with respective curators in parentheses:
CNIN – Colección Nacional de Insectos, Instituto de Biología, Universidad Nacional Autónoma de México, Distrito Federal, Mexico (Santiago Zaragoza-Caballero)
INBIO – Instituto Nacional de Biodiversidad, Heredia, Costa Rica (Ángel Solís)
NMNH – National Museum of Natural History, Washington, DC, United States of America (Floyd W. Shockley)
Despite examination of many collections from around the world, only two specimens representing the two new species described herein were found. As a consequence, the description of each new species is based on a single unique specimen (holotype). Due to similarity of the male genitalia of one of the new species with that of Epipocus manni Strohecker, the holotype of E. manni was also studied (Figs. 3B, 6). Measurements were made using an ocular micrometer as follows: body length from apical margin of clypeus to apex of elytra; width across elytra at widest part; height of elytra at highest part; length of each antennomere measured at mid-line; width of antennomere at widest part; width of pronotum at widest part; length of elytra from base to apex along suture, including scutellum. Species descriptions are based mainly on the same criteria used by Strohecker (Reference Shockley and Vandenberg1977) for species segregation. Features consistent with the generic redescription provided by Tomaszewska (Reference Tomaszewska2000) are not included in the species descriptions.
Photographs of the new species were generated using a Leica DFC3000g camera attached to a Leica Z16 APO A microscope. Composite images were created using Automontage software included in the Leica Application Suite 2.8.1 (Leica Microsystems, Wetzler, Germany). Habitus images of the holotype of E. manni were captured using a Canon EOS 7D (Canon, Tokyo, Japan) attached to a Visionary Digital Imaging System (Visionary Digital™, Palmyra, Virginia, United States of America). Images were then montaged and edited using Adobe Photoshop (San Jose, California, United States of America).
Taxonomy
Epipocus olmecus Arriaga-Varela, Tomaszewska, and Shockley, new species
Epipocus olmecus new species. (A) Dorsal habitus. (B) Ventral habitus. (C) Lateral habitus. (D) Close-up of metaventrite.
Epipocus olmecus new species. (A) Antenna. (B) Pronotum. (C) Prosternal process. (D) Right elytron, ventral. (E) Protibia. (F) Abdominal ventrite 5. (G) Male genital segment.
Median lobe, dorsal view. (A) Epipocus olmecus new species. (B) Epipocus manni Strohecker.
Holotype (male). “Barranca Metlac, 3/I/76, GRINVER” (CNIN).
Diagnosis. Epipocus olmecus is similar to Epipocus tristis tristis Guérin-Méneville, E. tristis costaricensis Strohecker, and E. manni. Epipocus olmecus differs from E. tristis subspecies by having the pronotum more transverse and less narrowed behind; elytra more elongate, widest near basal 1/3, with apex finely truncate; and by the shape of the aedeagus, which is more elongate with the apex truncate. The aedeagus of this species (Fig. 3A) resembles that of E. manni (Fig. 3B), but is more elongate anteriad of the genital pore and the ramus is regularly curved instead of geniculate. Moreover, the pronotum of E. manni (Fig. 6A) is rounded to the front angles, subsinuately narrowed basally, while the pronotum of E. olmecus has straight lateral margins, distinctly converging from the widest part towards the anterior angles and gently converging to the hind angles; the elytral apices are rounded in E. manni (Figs. 6A–6B), while in E. olmecus are finely truncate; and the antennomeres 10–11 are black in E. manni (Figs. 6A–6C) and orange in E. olmecus.
Description. Length 8.7 mm, width 4.01 mm, height 2.76 mm; body elongate oval, weakly convex (Figs. 1A–1C); feebly shiny; mainly black with ventral surfaces dark infuscate; antennomeres 10–11 and apex of 9, labrum, labial and maxillary palpi, apices of tibiae and tarsi of all legs orange; densely covered by short, decumbent, dark coppery pubescence.
Antenna (Fig. 2A) with 11 antennomeres, moderately long and slender, 1.5 times as long as head and pronotum combined; club about 0.25 times total antennal length; scape two times as long as wide, 2.0 times longer than pedicel; pedicel 1.2 times as long as wide; antennomeres 3–8 subequal in width; 3rd antennomere 3 times as long as wide, 2.3 times as long as pedicel; 4th and 5th antennomeres 1.65 times as long as wide, 1.3 times as long as pedicel; 6th antennomere 1.55 as long as wide, 1.2 times as long as pedicel; 7th and 8th antennomeres 1.43 as long as wide, slightly longer than pedicel; 9th antennomere 1.15 times as long as wide, 1.1 times as long as pedicel; 10th antennomere strongly produced internally, transverse, 0.8 times as long as wide, 1.1 times as long as pedicel; terminal antennomere as long as wide, 1.55 times as long as pedicel. Clypeus weakly transverse, 0.77 times as long as wide. Interocular distance 0.45 times as wide as head.
Pronotum (Fig. 2B) transverse, 0.54 times as long as wide, 2 times as wide as head, widest in apical third; strongly convergent to front angles, weakly convergent to hind angles; marginal area weakly reflexed in anterior 2/5, near front angles; front angles weakly produced, rounded anteriorly; hind angles produced posterolaterally to form a small acute spine; longitudinal sulci narrow, straight, reaching mid length of pronotum; densely and evenly punctate; punctures small, separated by 1 diameter. Prosternal process narrow, rounded apically (Fig. 2C).
Elytra 6.07 mm long; 1.52 times as long as wide (Fig. 2D); 3.75 times as long as and 1.3 times as wide as pronotum; elongate oval, widest near basal 1/3; densely punctate, punctures separated by 1–2 diameters; lateral margins narrow, continuously rounded, strongly convergent from widest point apically; apices very finely truncate; humeri prominent; epipleural fold moderately wide, strongly narrowed from mid length to apex. Hind wing well-developed, longer than elytra.
Metaventrite strongly transverse, 0.42 times as long as wide, slightly shorter than abdominal ventrite I, without depressions around discrimen (Fig. 1D).
Legs long and slender. Protibia with prominent tooth along inner margin at distal 2/3 (Fig. 2E); mesotibiae and metatibiae slender, about as long as their respective femora; mesotibiae and metatibiae with row of small tubercles along inner surface, more prominent on mesotibia; metatibiae 0.44 times as long as elytra; metatarsus 0.45 times as long as metatibia.
Abdomen with ventrite 1 as long as ventrite 2–4 combined; ventrite 5 elongate, as long as ventrite 2–4 combined, slightly rounded apically (Fig. 2F). Male genital segment with sternite rounded apically, edges asymmetrically incised (Fig. 2G). Aedeagus moderately stout and long, total length of median lobe about 3 times genital pore length, apex truncate, ramus curved (Fig. 3A).
Female. Unknown.
Distribution. MEXICO: Veracruz.
Etymology. The epithet of this species is derived from the Olmecs, who inhabited the southern portions of Veracruz and Tabasco states in Mexico and known as the “mother culture” of Mesoamerican peoples.
Remarks. The holotype of this species was previously studied during preparation of a review of Mexican Endomychidae (Arriaga-Varela et al. Reference Arriaga–Varela, Tomaszewska and Navarrete–Heredia2007) and was included as an undescribed species.
Due to the similarity of the genitalia of E. olmecus and E. manni, direct comparison between those species was desirable. Unfortunately the only known specimen of E. manni is the holotype, deposited by Strohecker (Reference Shockley and Vandenberg1977) in the NMNH collection. In a recent paper dealing with the types of Endomychidae deposited at NMNH (Shockley and Vandenberg Reference Shockley and Vandenberg2009), the type of E. manni was not included because it was not in the collection. However, it was recently found by the third author (F.W.S.), allowing us to directly compare the male genitalia of these species and confirming the new species as valid.
The description of E. olmecus brings the total to 21 species of Epipocus known from Mexico (Arriaga-Varela et al. Reference Arriaga–Varela, Tomaszewska and Navarrete–Heredia2007; Shockley et al. Reference Shockley, Tomaszewska and McHugh2009a).
Epipocus costatus Arriaga-Varela, Tomaszewska, and Shockley, new species
Epipocus costatus new species. (A) Dorsal habitus. (B) Ventral habitus. (C) Lateral habitus. (D) Close-up of metaventrite.
Epipocus costatus new species. (A) Antenna. (B) Pronotum. (C) Prosternal process. (D) Right elytron, ventral. (E) Hind wing. (F) Abdominal ventrite 5. (G) Ovipositor.
Holotype (female). “COSTA RICA. Prov. Puntarenas, A.C.O. Golfito, P. N. Corcovado, Est. Sirena. Send. Espavel. 10 m, 19 ABR 2001. A. Azofeifa. Intersección. L_S_270500_507900 #63648 // INB0003343957, INBIOCRI COSTA RICA” (INBIO).
Diagnosis. Epipocus costatus is easily distinguishable from all other black species of Epipocus by the prosternal process being widened posteriorly with a truncate apex, and the elytra having conspicuous longitudinal costae.
Description. Length 8.0 mm, width 4.0 mm, height 2.67 mm; body oval, moderately convex (Figs. 4A–C); feebly shiny; black with antennomeres 10–11 and apex of 9, labrum, labial and maxillary palpi, apices of femora, tibiae, and tarsi of all legs orange to light brown; densely covered by comparatively long, decumbent, coppery pubescence, golden on venter and on legs.
Antenna (Fig. 5A) with 11 antennomeres, moderately long and rather stout, 1.3 times as long as head and pronotum combined; club about 0.25 times total antennal length; scape 2 times as long as wide, 1.75 times as long as pedicel; pedicel 1.4 times as long as wide; antennomeres 3–8 subequal in width; 3rd antennomere 2.3 times as long as wide, 1.8 times as long as pedicel; 4th antennomere 1.9 times as long as wide, 1.3 times as long as pedicel; 5th antennomere 1.8 times as long as wide, 1.2 times as long as pedicel; 6th antennomere 1.4 times as long as wide, slightly shorter than pedicel; 7th and 8th antennomeres 1.3 as long as wide, 0.9 times as long as pedicel; 9th antennomere 1.1 times as long as wide, 1.1 times as long as pedicel; 10th antennomere strongly produced internally, transverse, 0.7 times as long as wide, 0.85 times as long as pedicel; terminal antennomere as long as wide, 1.35 times as long as pedicel. Clypeus weakly transverse, 0.77 times as long as wide. Interocular distance 0.41 times as wide as head.
Pronotum (Fig. 5B) transverse, 0.49 times as long as wide; 2.2 times as wide as head; subparallel along middle third; strongly, roundly convergent to front angles, weakly convergent to hind angles; front angles weakly produced, rounded anteriorly; hind angles produced and widely blunt apically; longitudinal sulci wide, curved inwards anteriorly, surpassing mid length of pronotum; densely and evenly punctate; punctures coarse, separated by 1 diameter. Prosternal process narrow, widening apically, truncate at apex (Fig. 5C).
Elytra 5.15 mm long; 1.29 times as long as wide (Fig. 5D); 3.17 times as long as and 1.2 times as wide as pronotum; broad oval, widest near basal 1/3; bearing conspicuous longitudinal costae, more conspicuously marked medially, less conspicuous in apical 5th; densely and rather coarsely punctate; punctures separated by 1–2 diameters; lateral margins distinctly thickened, continuously rounded, strongly convergent in the apical 3rd; apices rounded; humeri very weakly prominent; epipleural fold wide, continuously narrowed apically. Hind wings reduced, very narrow and shorter than elytra, with anal lobe and venation reduced; anal and cubital veins absent, radial vein present (Fig. 5E).
Metaventrite markedly transverse, about 0.3 times as long as wide, about 0.75 times as long as abdominal ventrite 1, posterior half depressed around discrimen (Fig. 4D).
Legs long and slender. Protibia unarmed, continuously widened distally; mesotibiae and metatibiae moderately stout, about as long as their respective femora; mesotibiae and metatibiae unarmed along inner surface; metatibiae 0.43 times as long as elytra; metatarsus 0.4 times as long as metatibia.
Abdomen with ventrite 1 about as long as ventrite 2–4 combined; ventrite 5 about 0.5 times length of ventrite 2–4 combined, emarginate apically (Fig. 5F). Ovipositor sclerotised, gonocoxites moderately elongate, gently narrowing apically, curved inwardly in apical half, apices rounded; styli absent (Fig. 5G).
Male. Unknown.
Distribution. COSTA RICA: Puntarenas.
Etymology. The epithet of this species is based on the distinctive longitudinal costae on the elytra.
Remarks. Six species and two subspecies belonging to groups II and IV have been recorded previously from Costa Rica (Strohecker Reference Shockley and Vandenberg1977; Shockley et al. Reference Shockley, Tomaszewska and McHugh2009a). The description of E. costatus brings the total to seven species of Epipocus known from Costa Rica.
Holotype of Epipocus manni Strohecker. (A) Dorsal habitus. (B) Ventral habitus. (C) Lateral habitus. (D) Labels.
Discussion
The species groups defined by Strohecker (Reference Shockley and Vandenberg1977) were based solely on colour, and as pointed out by Strohecker in that work, no conspicuous structural differences exist among the members of groups I and II. In contrast, the uniformly black species comprising group IV can be easily distinguished from members of the first two groups based on morphology. The main characters differentiating species of group IV from those of groups I and II are as follows: pronotum with lateral margins somewhat sinuate and converging at base, dorsal surfaces less punctate and setose, and the more complex aedeagal shape.
By far, the more divergent species group is group III, which presently includes only two species, Epipocus sallaei Gorham and E. similis Strohecker. Gorham (Reference Gorham1889), while describing his new species, noted the rather short, rounded elytra with wide epipleura, believing E. sallaei so divergent from the remaining Epipocus species that he suggested that it would likely eventually be shown to belong to a different genus. However, rather than erect a new genus to accommodate it, he assigned it to Epipocus on the basis of antennal structure and the shape of the prosternal process. He was further concerned about the fact that all the specimens he had studied were females. Strohecker (Reference Shockley and Vandenberg1977) noted Gorham’s concern regarding the peculiarity of E. sallaei but added some additional characters (e.g., male protibia unarmed, antennomeres 9–10 with disto-internal angle poorly developed). As with Gorham, Strohecker (Reference Shockley and Vandenberg1977) also decided to retain E. sallaei and E. similis within Epipocus.
Although based on single specimens, the two species described herein are easily distinguished from all congeners. Further, Epipocus olmecus is easily assigned to the E. rufitarsis group (IV). Conversely, the conspicuous longitudinal costae on elytra and the posteriorly widened and apically truncate prosternal process of Epipocus costatus not only separate it from other black-coloured species, but are not found in any other Epipocus species. Although a truncate prosternal process is found among members of Epopterus and Anidrytus, E. costatus clearly has an Epipocus-type labial palp and the antennal structure further confirms correct attribution to Epipocus. As no male specimen is yet known, we refrain from proposing a new species group within Epipocus to accommodate this unusual species until additional specimens (especially males) can be studied. Undoubtedly, study of male genitalia of this species would improve understanding of the species and species-group limits and diversity within Epipocus.
Acknowledgements
The authors want to thank the curators of the museums, Santiago Zaragoza-Caballero (CNIN) and Ángel Solís (INBio), for their permission to study these interesting specimens. Beatriz Rodríguez-Velez provided valuable feedback on an early draft of the descriptions. Susana Guzmán Gómez, Unidad de Informática para la Biodiversidad (UNIBIO) of the Instituto de Biología, Universidad Nacional Autónoma de México, provided technical assistance with the photographs of the two new species. Karie Darrow, Department of Entomology, National Museum of Natural History, Smithsonian Institution, took the high-resolution habitus images of the holotype of E. manni and its labels.
