The Leptotyphlopidae, descriptively called threadsnakes or wormsnakes, is one of five families comprising the most ancient but highly specialized clade of snakes, the Scolecophidia, which dates back to the Jurassic Period (ca. 155 mya). Scolecophidians are the least studied and poorest known group of snakes, both biologically and taxonomically. Due to their subterranean habitat, nocturnal lifestyle, small size, and drab coloration, these snake are extremely difficult to find and seldom are observed or collected. Epictia is one of six genera found in the New World, with a distribution extending throughout Latin America. Whereas most Epictia are uniform brown or black, some species are brightly colored. Epictia tenella, the most wide-ranging member of the genus, occurs throughout much of northern South America. Pictured here is an individual from Trinidad that exhibits several distinctive features, including yellow zigzag stripes, relatively large bulging eyes, contact of the supraocular and anterior supralabial shields, and the presence of numerous sensory pits on the anterior head shields. ' © John C. Murphy 215 www.mesoamericanherpetology.com www.eaglemountainpublishing.com ISSN 2373-0951 Version of record:urn:lsid:zoobank.org:pub:A6B8D5BF-2E06-485A-BD7F-712D8D57CDE4 Morphological review and taxonomic status of the Epictia phenops species group of Mesoamerica, with description of six new species and discussion of South American Epictia albifrons, E. goudotii, and E. tenella (Serpentes: Leptotyphlopidae: Epictinae) VAN WALLACH 4 Potter Park, Cambridge, Massachusetts 02138, United States. E–mail: [email protected] ABSTRACT: I examined the “Epictia phenops species group” of Mesoamerica, and recognize 11 species as valid (E. ater, E. bakewelli, E. columbi, E. magnamaculata, E. phenops, plus four new species from Mexico, one from Honduras, and one from Panama). Epictia goudotii does not occur in Panama, but only in South America. I used head shields, color patterns, and visceral characters to differentiate the Mesoamerican taxa, and compared these species externally and internally with E. albifrons, E. goudotii, and E. tenella of South America. I selected a neotype for E. albifrons from a topotypic series, and provide identification keys for the genera of tribe Epictini, the scolecophidians of the state of Pará, Brazil, mem- bers of the “E. phenops species group,” and the Epictia of Mesoamerica and northern South America. Key Words. Epictia ater, E. bakewelli, E. columbi, E. magnamaculata, distribution, morphology, neotype, new species, viscera RESUMEN: Examiné el “grupo de especies de Epictia phenops” de Mesoamérica, y reconozco 11 especies como válidas (E. ater, E. bakewelli, E. columbi, E. magnamaculata, E. phenops, además de cuatro nue- vas especies para México, una en Honduras y otra en Panamá). Epictia goudotii no ocurre en Panamá, solamente en Suramérica. Usé las escamas dorsales de la cabeza, patrón de coloración y características viscerales para diferenciar los taxones de Mesoamérica, y comparé estas especies externa e internamente con E. albifrons, E. goudotii y E. tenella de Suramérica. Seleccioné un neotipo para E. albifrons de la serie topotípica, y proporciono unas claves de identificación para los géneros de la tribu Epictini, los scolecofidios del estado de Pará, Brasil, miembros del “grupo de especies de E. phenops” y los Epictia de Mesoamérica y norte de Suramérica. Palabras Claves: Epictia ater, E. bakewelli, E. columbi, E. magnamaculata, distribución, morfología, neotipo, nuevas especies, vísceras Citation: Wallach, V. 2016. Morphological review and taxonomic status of the Epictia phenops species group of Mesoamerica, with description of six new species and discussion of South American Epictia albifrons, E. goudotii, and E. tenella (Serpentes Leptotyphloptidae: Epictinae) 3: 216–374. Copyright: Wallach, 2016. This work is licensed under a Creative Commons Attribution-NoDerivate 4.0 International License. Received: 2 April 2016; Accepted: 8 May 2016; Published: 29 June 2016. Mesoamerican Herpetology 216 June 2016 | Volume 3 | Number 2 Wallach Taxonomy of Epictia INTRODUCTION Among all snakes, the Scolecophidia are unsurpassed in their difficulty of identification, scale counting, head shield identification, accuracy of illustration, and discovery of diagnostic characters of systematic and taxonomic value. In part, this situation results from their minute to small size, rarity of collection and field observations due to their secretive habits and fossorial lifestyle, and simplification of the general serpentine body plan. The Leptotyphlopidae is the sister group to the Typhlopoidea (Gerrhopilidae, Typhlopidae, and Xenotyphlopidae), and together they form the sister group to the Anomalepididae (Vidal et al., 2010; Pyron et al., 2013; Pyron and Wallach, 2014). Even within the five scolecophidian families (Anomalepididae with 18 species; Gerrhopilidae with 18 species; Leptotyphlopidae with ca. 130 species; Typhlopidae with ca. 400 species; and Xenotyphlopidae with a single species; Wallach et al., 2014; Uetz and Hošek, 2016), the Leptotyphlopidae, by far, is the most difficult group to study. Not only are mem- bers of this family the smallest of all snakes, but they also exhibit no variation in the number of longitudinal scale rows. In most of the 130 known species, only 14 scale rows are present throughout the body (which is the same as the 13-13-13 alethinophidian scale row formula with unenlarged ventrals), but 16 longitudinal rows are present in a few species. Their internal anatomy also is reduced to a minimum, with the respiratory system consisting of only a single, short, right lung (whereas, in addition to the right lung, a tracheal lung also is present in all the other scolecophidian families, and a left lung is found in some Typhlopidae). Thus, characters in the Leptotyphlopidae are at a premium. Based on a molecular analysis, Adalsteinsson et al. (2009) divided the genus Leptotyphlops (sensu lato) into the following 11 genera: Epacrophis Hedges, Adalsteinsson, and Branch In Adalsteinsson et al., 2009; Epictia Gray, 1845; Guinea Hedges, Adalsteinsson, and Branch In Adalsteinsson et al., 2009 (= Tricheilostoma Jan, 1861); Leptotyphlops Fitzinger, 1843; Mitophis Hedges, Adalsteinsson, and Branch In Adalsteinsson et al., 2009; Myriopholis Hedges, Adalsteinsson, and Branch In Adalsteinsson et al., 2009; Namibiana Hedges, Adalsteinsson, and Branch In Adalsteinsson et al., 2009; Rena Baird and Girard, 1853; Siagonodon Peters, 1881; Tetracheilostoma Jan, 1861; and Tricheilostoma Jan, 1861 (= Trilepida Hedges, 2011). Six genera were recognized within the sub- tribe Epictina, tribe Epictini, and subfamily Epictinae (Epictia, Mitophis, Rena, Siagonodon, Tetracheilostoma, and Trilepida) and can be identified by using the following key. Key to the genera of the tribe Epictini 1a. Supraocular absent .......................Siagonodon 1b. Supraoculars present ...............................2 2a. Supraoculars large, wider than long ..............Epictia 2b. Supraoculars small, as long as wide . 3 3a. Supralabials 4 (3–4 in M. leptepileptus) . 4 3b. Supralabials 2–3 ..................................5 4a. Total middorsals < 200 ................Tetracheilostoma 4b. Total middorsals > 250 .......................Mitophis 5a. Venter brown; supralabials 3.................. Trilepida 5b. Venter white; supralabials usually 2 (3 in R. bressoni, R. dissecta, and R. mypoica) . .Rena The three confusing species that form the focal point of this study are Epictia albifrons (Wagler In Spix, 1824) from Brazil, Epictia goudotii (Duméril & Bibron, 1844) from Colombia, and Epictia phenops (Cope, 1875) from Mexico. This complex of species variously has been referred to as the albifrons species group, the goudotii species group, and the phenops species group, with the majority of researchers considering E. albifrons and E. goudotii to be species complexes sorely in need of revision (Taylor, 1939; Schmidt and Walker, 1943; Thomas, 1965; Wilson and Hahn, 1973; Franco and Pinto, 2009; Ugueto and Rivas, 2010). These three species and their relatives are Mesoamerican Herpetology 217 June 2016 | Volume 3 | Number 2 Wallach Taxonomy of Epictia remarkably similar in external appearance, and various subspecies previously have been allocated to these taxa (Dunn and Saxe, 1950; Roze, 1966; Peters et al., 1970). For 150 years enormous confusion has existed with three species, each involving multiple species or subspe- cies, along with a number of presently undescribed forms. Klauber (1939: 59) stated that, “it was immediately evi- dent that L. albifrons, as usually defined, is a complex of a number of species and subspecies.” Schmidt and Walker (1943: 305) referred to “the Leptotyphlops albifrons of authors is an omnium gatherum of species of varying degrees of distinctness.” Schmidt and Inger (1951: 456) noted that “the albifrons of authors having been shown to be a com- plex of quite distinct species.” Thomas (1965: 6) claimed that “there is obviously more than one species involved in the material I have seen” when referring to South American albifrons. Wilson and Hahn (1973: 120) remarked that the albifrons complex was in “a notorious state of taxonomic confusion.” Vanzolini et al. (1980: 15) stated the albifrons group to be very difficult, with examples from very diverse regions that show apparent E. albifrons char- acters, but in reality consist of more than one species. Vanzolini (1996: 281–282) remarked that E. albifrons was “certainly