Introduction

The beetle family Telegeusidae consists of 21 species belonging to 3 genera: Telegeusis Horn (16 spp.) (Fig. 1a) distributed in southern United States, Mexico and Panama; Pseudotelegeusis Wittmer (4 spp.) (Fig. 1b) distributed in Mexico, Venezuela, Ecuador, French Guiana, Trinidad and Peru; and Pseudokarumia Pic (1 sp.) (Fig. 1c) distributed in Costa Rica and Panama (^{Allen & Hutton, 1969}; ^{Barber, 1952}; ^{Constantin, 2010}; ^{Fleenor & Taber, 2001}; ^{Horn, 1895}; ^{Martin, 1931}; ^{Pic, 1931}; ^{Roza et al., 2019}; ^{Wittmer, 1976}; ^{Zaragoza-Caballero, 1975}, ¹⁹⁹⁰, ²⁰⁰⁸; ²⁰¹⁵; ^{Zaragoza-Caballero & Rodríguez-Velez, 2011}). Mexico has the highest diversity of telegeusids, with 12 species of Telegeusis (^{Horn, 1895}; ^{Martin, 1931}; ^{Zaragoza-Caballero, 1975}, ¹⁹⁹⁰, ²⁰¹⁵; ^{Zaragoza-Caballero & Rodríguez-Velez, 2011}) and 1 species of Pseudotelegeusis (^{Zaragoza-Caballero, 2008}).

Figure 1 Genera of Telegeusidae. a) Telegeusis moroni ^{Zaragoza-Caballero, 2015}; b) Pseudotelegeusis jiliotupaensis Zaragoza-Caballero, 2008; c) Pseudokarumia angustata ^{Pic, 1931} (Photograph by Jennifer Thomas, Division of Entomology, University of Kansas Biodiversity Institute©). 

The family’s position in Elateroidea is unclear. ^{Horn (1895)} included Telegeusis debilis Horn in Drilidae. ^{Barber (1952)} suggested a generic relationship with Lymexyloidea. ^{Martin (1931)} transferred Telegeusis to Cantharidae. Subsequently, ^{Zaragoza-Caballero (1990)} discussed the relationship of this family with Phengodidae. Moreover, different phylogenetic hypotheses have resulted from different analyses. ^{Branham and Wenzel (2001}, ²⁰⁰³⁾ recovered a clade where Telegeusis and Pseudotelegeusis were related with several genera of Phengodidae, Cantharidae and Omethidae. ^{Hunt et al. (2007)}, based on molecular evidence of 3 genes, found through a Bayesian statistical approach that Telegeusidae is related with Omethidae. ^{Bocakova et al. (2007)}, ^{Kundrata and Bocak (2011)} and ^{Kundrata et al. (2013)}, based on molecular evidence, related Telegeusis with Omethidae. ^{Kundrata et al. (2014)} proposed to synonymize Telegeusidae with Omethidae, giving telegeusids a subfamilial rank. ^{Zaragoza-Caballero and Zurita-García (2015)}, based on morphological evidence, suggested a close relationship between Telegeusidae and Phengodidae; Telegeusidae was found to be nested within Phengodidae as the sister group of Penicillophorinae. In a recent phylogenetic study focusing on Cydistinae, the only species of telegeusid sampled was nested within a clade with Artematopodidae and Omethidae (^{Kundrata et al., 2019}). Telegeusidae’s taxonomic position is unclear, so we treat it herein as a family.

Telegeusids, or long-lipped beetles, are recognized by their remarkably long labial and maxillary palpi with long terminal palpomeres; body distinctly flattened, narrow and elongate; elytra short, moderately densely clothed with erect or semierect setae; antennae 11-segmented, filiform to serrate; clypeus bi- or trilobate; pronotum quadrate, with margins beaded; abdomen with 8 or 7 (Pseudotelegeusis) ventrites; tibial spurs well developed; and tarsal formula 5-5-5 (^{Ivie, 2002}; ^{Lawrence, 2010}; ^{Miller, 2002}). All known individuals are adult males, and no females have been described (^{Lawrence, 2010}). Little is known about the natural history and immature stages of telegeusid beetles. Presumably, females are flightless or neotenic, given the repeated occurrence of neoteny in the elateriform lineage (^{Bocakova et al., 2007}). According to various works (^{Allen & Huntton, 1969}; ^{Fleeno & Taber, 2001}; ^{Roza et al., 2019}; ^{Wittmer, 1976}; ^{Zaragoza-Caballero, 2008}, ²⁰¹⁵; ^{Zaragoza-Caballero & Rodríguez-Velez, 2011}), specimens of Telegeusidae have been collected by using different types of traps (Malaise, flight intercept and light), from desert to humid areas, mainly during April, July and August.

Telegeusid beetles are rarely collected; this is reflected in the number of the genera and species described. In this paper, we describe and illustrate Stenodrilus gen. nov., Stenodrilus rodolfoi sp. nov., Platydrilus gen. nov., and Platydrilus magaliae sp. nov. from Chiapas, Mexico. Also, a key to all genera of Telegeusidae is provided.

Material and methods

Specimens studied were collected with flight intercept, blacklight and Malaise traps in the vicinity of Tacaná volcano, Chiapas, Mexico. Specimens were examined and measured using a Carl Zeiss Discovery V8® stereomicroscope. Measurements are in millimeters. Genitalia were dissected and, after examination, were transferred to microvials which were then pinned beneath the specimens. Anatomical terms and characters used here are those of ^{Horn (1895)}, ^{Barber (1952)}, ^{Sharp and Muir (1912)}, ^{Zaragoza-Caballero (1975)}, and ^{Zaragoza-Caballero and Rodríguez-Velez (2011)}. Photographs were obtained using a Zeiss Axio Zoom V-16® stereoscopic microscope equipped with an Axiocam MRC5® camera. Electron micrographs were obtained using a Hitachi® S-2460N (15KV) scanning electron microscope. All specimens are deposited in the National Collection of Entomology (CNIN), Instituto de Biología, UNAM.

Descriptions

Stenodrilus gen. nov. (Figs. 2a-g, 3a, b)

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Type species: Stenodrilus rodolfoi sp. nov.

Figure 2 Stenodrilus gen. nov. a) Punctation close to eyes; b) pronounced median tooth on clypeus; c) maxilar palpi; d) labial palpi; e) membranous wings; f) ventral view of aedeagus; g) lateral view of aedeagus. 

Figure 3 Stenodrilus rodolfoi sp. nov. a) Dorsal view; b) ventral view. 

Diagnosis. This genus can be distinguished from Telegeusis by the last labial palpomere not greatly enlarged and elongated; from Pseudotelegeusis by the filiform antennae and the 2-segmented labial palpi; and from Pseudokarumia by the smooth tibial spines (see a complete comparison between genera in Table 1). This new genus is most similar, and probably closely related, to Platydrilus gen. nov., but is easily recognizable by the coarsely punctate surface close to eyes, gula with 2 sutures, clypeus with a very pronounced median tooth, aedeagus not robust and lateral lobes more than 3 times longer than wide.

Description. Color: head yellow with sides dark brown; pronotum yellow; antennae and elytra dark brown (except yellow last antennomere); body ventrally yellow to brown. Body: elongate, parallel-sided, dorsoventrally flattened, clothed with dense, erect yellow setae. Head: surface coarsely punctate close to eyes (Fig. 2a); width behind eyes greater than longitudinal diameter of eye. Antennal tubercles slightly prominent. Antennae 11-segmented, filiform, inserted anterior to eyes in lateral margins of head. Eyes hemispherical, finely faceted, widely separated. Frons wider than long. Frontoclypeal suture complete. Clypeus wider than long, with a pronounced median tooth (Fig. 2b). Mandibles falciform. Galea dilated, with apex setose. Maxillary palpi 3-segmented, shorter than antennae; last palpomere spatulate, 6 times longer than palpomere 2 (Fig. 2c); labial palpi 2-segmented, last palpi shorter than the scape (Fig. 2d). Tentorium with 1 pit. Gula with 2 sutures (Fig. 2d). Thorax: pronotum quadrate, punctate, setose; edges margined, lateral margins subparallel to slightly sinuate; anterior and posterior angles pits; disc slightly convex, clothed with short, erect yellow setae. Scutellum hidden by pronotum, longer than wide, apex truncate, surface clothed with erect setae. Elytra with external margins parallel, apex rounded, dorsally clothed with erect setae. Epipleura present on elytral basal half, integument shiny, rugose. Metathoracic wings, revealing 2 abdominal ventrites when folded. Venation reduced; anterior radial vein (RA) somewhat sclerotized; radial cell (CR) obsolete; radial, posterior radial and median posterior veins fused; cubital 1 (C1), cubital 2 (C2) and anal posterior vein (AP) well defined (Fig. 2e). Prosternum reduced, wider than long. Mesosternum short. Metasternum rectangular. Legs: trochanters present on all 3 pairs of legs, elongate. Anterior and middle coxae conical; posterior coxae almost rectangular. Femora fusiform, flattened. Tibiae elongate, with 2 apical smooth spines. Tarsi 5-segmented; tarsomere 1 equal in length to 2-4 combined; claws simple. Abdomen: with 8 non-fused ventrites; pygidium triangular. Aedeagus (Fig. 2f, g) trilobate; basal piece nearly covering dorsally and laterally basal half of lateral lobes; in ventral view, basal piece longitudinal margins diverging strongly apically; lateral lobes symmetrical, more than 3 times longer than wide, oval, twisted near apex; apex rounded, granulate, with long semierect setae; median lobe projected ventrally, weakly arched, narrowed apically, covered by median strut.

Taxonomic summary

Etymology. This species is named after Rodolfo Cancino López, one of the collectors of the species.

Type material. Holotype male: Mexico. Chiapas, Cacahoatán, Ejido Benito Juárez, El Plan cerca de Estación Meteorológica, 7/IX/2018, 1,487 m asl, 15°05’27.66” N, 92°08’50.5” W, T. Luz negra, Cancino-López R.J. & Luna-Luna A.M. colls. Paratypes, 2 males: Chiapas, Cacahoatán, Ejido El Águila, 7/IX/2018, 1,209 m asl, 15°05’33.78” N, 92°10’52.02” W, T. Luz negra, Cancino-López R.J. & Luna-Luna A.M. colls; Cacahoatán, Ejido El Aguila, 11-12/II/2018, 1,210 m asl, 15°05’36.96” N, 92°10’48.36” W, T. malaise 1, Cancino-López R.J. & Luna-Luna A.M. colls.

Platydrilus gen. nov. (Figs. 4a-g, 5a, b)

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Figure 4 Platydrilus gen. nov. a) Punctation close to eyes; b) short median tooth on clypeus; c) maxilar palpi; d) labial palpi; e) membranous wings; f) ventral view of aedeagus; g) lateral view of aedeagus. 

Figure 5 Platydrilus magaliae sp. nov. a) Dorsal view; b) ventral view. 

Type species: Platydrilus magaliae sp. nov.

Diagnosis. This genus is distinguished from Telegeusis by the lack of greatly enlarged and elongated last labial palpomere; from Pseudotelegeusis by the filiform antennae and the 2-segmented labial palpi; and from Pseudokarumia by the non-serrated mesotibial spines (see a complete comparison between genera in Table 1). Platydrilus gen. nov. is most similar, and probably closely related, to Stenodrilus gen. nov., but is easily recognizable by the head somewhat punctate, gula with 1 suture bifurcating at base, clypeus with a noticeably short median tooth and robust aedeagus with lateral lobes longer than wide.

Description. Color: head, pronotum, antennae and elytra brown; ventrally yellow to brown. Body. Form elongate, parallel-sided, dorsoventrally flattened, clothed with dense, decumbent yellow setae. Head: surface somewhat punctate (Fig. 4a), width behind eyes 2.5 times greater than longitudinal diameter of eye; mouthparts prognathous. Antennal tubercles prominent. Antennae 11-segmented, filiform, inserted anterior to eyes in lateral margins. Eyes situated on lateral margins, spherical, finely faceted, widely separated. Frons wider than long. Frontoclypeal suture complete. Clypeus wider than long, with a short median tooth (Fig. 4b). Mandibles falciform. Galea bullet-shaped, setose. Maxillary palpi 3-segmented, shorter than antennae; last palpomere spatulate, more than 6 times longer than palpomere 2; labial palpi 2-segmented (Fig. 4c), last palpi as long as scape (Fig. 4d). Tentorium with 1 pit. Gula with 1 suture bifurcating at base (Fig. 4d). Thorax: pronotum quadrate; edges margined, lateral margins subparallel; anterior and posterior angle pits; disc flat, clothed with short, erect yellow hairs. Scutellum hidden by pronotum, wider than long, apex truncate, surface punctate, clothed with erect setae. Elytra with external margins parallel, apex rounded, dorsally and ventrally clothed with decumbent setae. Epipleura present on elytral basal half, integument shiny, rugose. Membranous wings, revealing 1 tergite when folded. Venation reduced; anterior radial vein (RA) sclerotized; radial cell (CR) and R3 fused, obsolete; posterior radial and median posterior veins fused; cubital 1 (C1), cubital 2 (C2) and anal posterior vein (AP) well defined (Fig. 4e). Prosternum reduced, wider than long. Mesosternum short. Metasternum as long as wide. Legs: trochanters present on all 3 pair of legs, elongate. Anterior, middle and posterior coxae conical. Femora fusiform, flattened. Tibiae elongate, with 2 smooth, apical spines. Tarsi 5-segmented; length of tarsomeres 1 about equal to 2-4 combined; claws simple. Abdomen: with 8 non-fused ventrites; pygidium subtriangular. Aedeagus (Fig. 4f, g) trilobate, robust; basal piece covering dorsally basal half of lateral lobes; in ventral view, basal longitudinal margins of basal piece widely separated, moderately diverging apically; lateral lobes as long as wide, oval, slightly twisted near apex; apex rounded, granulate, with long, semierect setae; median lobe projected ventrally, erect, weakly widening apically, covered by medium strut.

Discussion

Among Telegeusidae, the male genitalia have not been previously used to differentiate between genera or species. The study of the structure of the male genitalia allowed us to recognize the 2 new genera presented in this study. According to descriptions and illustrations of male genitalia in the other genera of Telegeusidae (^{Allen & Hutton, 1969}; ^{Barber, 1952}; ^{Lawrence, 2010}; ^{Zaragoza-Caballero, 1975}, ¹⁹⁹⁰), lateral lobes are very wide and are not twisted towards the apex; in the new genera, however, the lobes are twisted near apex and slenderer.

The new genera and species described here were collected in March, February and September in the Tacaná Volcano Biosphere Reserve, Chiapas, in shade-coffee plantations and cloud forest. The cloud forest is one of the most threatened vegetation types in Mexico. On the slopes of Tacaná volcano, the cloud forest area is highly reduced compared to other forests from the Sierra Madre de Chiapas (^{Challenger et al., 2010}). On the other hand, shade-coffee plantations are important repositories of biological diversity and could be used as corridors between natural areas for some groups of animals (^{Moguel & Toledo, 1999}; ^{Perfecto et al., 1996}). However, this change in the ecosystem may put pressure on the species and therefore a change in their composition. The new genera and species of these rare beetles from this type of vegetation show the need to search for efficient strategies to conserve the environment around this volcano in order to preserve its fauna and flora.