Walter E. Schargel

An Enigmatic New Snake from Cloud Forest of the Península de Paria, Venezuela (Colubridae: Genus Taeniophallus?)

Abstract The snake Taeniophallus nebularis, new species, is known from a single specimen collected in montane cloud forest, 800 m above sea level, Península de Paria, northeastern Venezuela. It is a small “xenodontine” colubrid (adult male, 492 mm total length); dorsal scales in 19-19-17 rows, smooth, with paired apical pits anteriorly; brown dorsally and grayish laterally, with ill-defined pattern; white postocular stripe; and bright yellow midventrally between serrated black edges. The species is easily diagnosed, although assignment to Taeniophallus is problematic. However, a few suggestive characters are shared with T. brevirostris and T. nicagus. These species, presumably the closest geographic relatives of T. nebularis, occur in the Amazon basin and the Guianas, indicative of a biogeographic parallel with certain plants. Taeniophallus occipitalis, with extreme scale-row reduction and a distinctive color pattern possibly derived from a brevirostris-like precursor, is widely distributed south of the Amazon. Four additional species of Taeniophallus s.l. comprise the monophyletic affinis species group centered in southeastern Brazil. The genus Echinanthera (also centered in southeastern Brazil) is sometimes expanded to include all of Taeniophallus. Echinanthera s.s. is viewed as a demonstrably monophyletic group of six named species, whereas relationships of the subgroups of Taeniophallus s.l. among themselves and to Echinanthera remain uncertain. Evolutionary divergence in copulatory organs of the otherwise similar Taeniophallus nicagus and T. brevirostris is extraordinary, suggesting that uncritical weight cannot safely be assigned to hemipenial characters of presumptive relatives. The hemipenis of Taeniophallus nebularis differs from those of other taxa discussed in being conspicuously bilobed for nearly a third of its length. However, some degree of bilobation is symplesiomorphic for these snakes, as evidenced by presence or absence of weak bilobation in a few species and divided insertions of retractor muscles in all. The penial asulcate interspinal gap in T. nebularis also might be symplesiomorphic for Taeniophallus s.l. and Echinanthera s.s., but homologies and level of generality for this character are not yet clear.

BRIDGING THE GAP IN PROCTOPORUS DISTRIBUTION: A NEW SPECIES (SQUAMATA: GYMNOPHTHALMIDAE) FROM THE ANDES OF VENEZUELA

We describe a new species of Proctoporus from the Cordillera de Mérida, Venezuela. The new species is the first Proctoporus recorded from this mountain range and fills a large hiatus in the known distribution of the genus. The new species possesses a uniquely elongated second supralabial scale and a combination of other characters that distinguish it from all other congeners. Due to its distinctness from the two other species of Proctoporus from Venezuela, the new species does not appear to be a member of the P. luctuosus group or any of the other recognized Proctoporus species groups. Resumen Describimos una nueva especie de Proctoporus de la Cordillera de Mérida, Venezuela. La nueva especie es la primera especie registrada para esta cordillera y cierra un vacío grande en la distribución conocida del género. La nueva especie posee la segunda escama supralabial exageradamente elongada, lo cual es un cáracter único en el género, y también la combinación de varios otros cáracteres que distinguen esta especie de todas las demás. Por ser muy distinto de las otras dos especies de Proctoporus de Venezuela, la nueva especie no se coloca en el grupo de P. luctuosus, ni en los otros grupos establecidos de Proctoporus.

The Hemipenes of Some Snakes of the Semifossorial Genus Atractus, with Comments on Variation in the Genus

Abstract The hemipenes of seven species of Atractus (Atractus emigdioi, Atractus major, Atractus mariselae, Atractus poeppigi, Atractus torquatus, Atractus univittatus, and Atractus ventrimaculatus) are described. Hemipenial morphology in this poorly known genus of snakes is found to be particularly variable among the species studied. Additionally, the primitive unicapitate hemipenal condition is more widespread among Atractus than was previously thought. Given the drastic variation in hemipenal morphology observed in Atractus, it is likely that characters derived from studying this organ may prove especially useful for future work on intrageneric relationships among members of this genus.

Morphological Extremes—Two New Snakes of the Genus Atractus from Northwestern South America (Colubridae: Dipsadinae)

Abstract Two new Andean snakes exhibit extreme morphology in a genus of South American dipsadine colubrids. One, Atractus attenuatus, new species, is a slender, exceptionally attenuated snake 420 mm in total length (adult male holotype), with 17 scale rows, a high ventral + subcaudal count (226), and an extremely vague pattern of numerous, closely spaced, indistinct dark crossbars on a brown ground color. Atractus attenuatus comes from 1000 m elevation in the northern end of the Cordillera Central (Sabanalarga, Antioquia, Colombia). A geographic neighbor, Atractus sanguineus Prado, is of similar morphology but differs in having distinct, widely spaced crossbars on a red ground color. At another extreme, Atractus gigas, new species, is a very robust snake that exceeds a meter in length (adult female holotype 1040 mm in total length), with a hint of pale transverse dorsal bars on a brown ground color. It is the largest known Atractus, differing in color pattern and details of scutellation from the several o...

A New Species and a New Record of Atractus (Serpentes: Colubridae) from the Andes of Venezuela

Abstract A new species of Atractus is described from the Cordillera de Mérida, Venezuela. The new species can be distinguished from all other congeners by the combination of 15 dorsal scale rows at midbody and a color pattern consisting of two pale dorsolateral stripes on a dark ground color. Additionally Atractus pamplonensis is reported for the first time for Venezuela.

Phylogenetic systematics of the genus Gonatodes (Squamata: Sphaerodactylidae) in the Guayana region, with description of a new species from Venezuela

The phylogenetic relationships and species boundaries of the diurnal geckos of the genus Gonatodes in the Guayana region are examined. Seven species of Gonatodes are recognized for the region, six of which are endemic to this region and form a monophyletic group together with G. hasemani from the southern part of the Amazon Basin. Two of the six species in this group are new to science, one of which is endemic to Venezuela and it is described here. Taxonomic accounts are provided for all the Venezuelan species of Gonatodes that are endemic to the Guayana region. The phylogenetic relationships of Gonatodes suggest that the diversity of this genus in the Guayana region has resulted mostly from in situ diversification rather than multiple colonization events by different lineages. The phylogenetic analyses also support that G. antillensis, the only nocturnal species in the genus, is indeed nested within Gonatodes, indicating re-evolution of some traits associated with nocturnal life. Finally, we comment on a recently proposed framework of temporal diversification in Gonatodes and suggest that we are still a long way from attaining a complete understanding about the systematics of this genus.

Rediscovery of Atractus microrhynchus and Reappraisal of the Taxonomic Status of A. emersoni and A. natans (Serpentes: Dipsadidae)

Abstract The species Rhabdosoma microrhynchum (now Atractus microrhynchus) was originally described based on a single specimen collected by the Orton Expedition at “Guayaquil,” in the Guayas province on the Pacific coast of Ecuador. The holotype is currently lost and all specimens previously referred to this species were misidentified on the basis of material from Peruvian Amazonia. While examining museum collections and conducting fieldwork in the Pacific lowlands of Ecuador and Peru, we found specimens assignable to A. microrhynchus. In this study, we report the morphological variation in these new specimens of A. microrhynchus and evaluate the taxonomic status of the Amazonian species previously confused with it. We restrict the concept of A. microrhynchus to the Pacific lowland populations from Ecuador and Peru, and we designate a neotype for the species. Based on the examination of the types of A. emersoni and A. natans from Amazonia, we found that there is wide overlap in the internal and external characters of both taxa. Therefore, A. emersoni is relegated to the synonymy of A. natans. Furthermore, we compared A. microrhynchus with all congeners and discuss its affinities with the A. multicinctus species group based on shared, exclusive hemipenial features. Resumen La especie Rhabdosoma microrhynchum (ahora Atractus microrhynchus) se basó en un solo espécimen colectado por la Expedición Orton en “Guayaquil,” provincia de Guayas, costa Pacífica del Ecuador. El holotipo está actualmente perdido y todos los especímenes previamente referidos a esta especie fueron identificados erróneamente sobre la base de material de la Amazonía Peruana. Durante la revisión de colecciones de museos y la realización de trabajo de campo en las tierras bajas del Pacífico de Ecuador y Perú, encontramos especímenes que se pueden asignar a A. microrhynchus. En este estudio, reportamos sobre la variación morfológica de estos nuevos especímenes de A. microrhynchus y evaluamos el estado taxonómico de las especies Amazónicas previamente confundidas con esta. Restringimos el concepto de A. microrhynchus para las poblaciones de las tierras bajas del Pacífico de Ecuador y Perú y designamos un neotipo para la especie. Basados en la revisión de los tipos de A. emersoni y A. natans de la Amazonía, encontramos que hay una amplia superposición de las características de ambos taxones. Por lo tanto, A. emersoni se coloca bajo la sinonímia de A. natans. Más aún, comparamos A. microrhynchus con todos sus congeners y sus afinidades con el grupo-de-especies A. multicinctus son discutidos sobre la base de las características hemipenianas exclusivas compartidas.

Coding meristic characters for phylogenetic analysis: a comparison of step-matrix gap-weighting and generalized frequency coding.

Meristic characters, or counts of discrete serially ho-mologous structures, are a distinctive and ubiquitousclass of quantitative organismal variation. Meristic char-acters share many properties with morphometric char-acters (i.e., measurements, proportions, etc.): they arereadily described numerically, they usually vary withinand among taxa, and they often appear to follow similarunderlying frequency distributions (e.g., Burbrink, 2001;Allsteadt et al., 2006). Based on these similarities, meris-tic characters are generally lumped with morphometriccharactersintothebroadercategoryof“quantitativecon-tinuouscharacters”forphylogenyreconstruction.Meris-tic characters also exhibit properties that differ subtly,butperhapsimportantly,frommorphometriccharacters.It has been increasingly recognized that morphologicalsystematists often code intrinsically quantitative char-acters as qualitative by artificially compartmentalizingvariation into relatively few ordered states (e.g., inter-clavicle,medianprocess:0=normallength;1=reduced;Etheridge and de Queiroz, 1988). This practice alwaysproduces arbitrary character states with morphometricdata. In contrast, meristic characters may be viewed asdiscrete traits that, depending on the range of variation,showacontinuumfrombinarytransformations,throughmultistate polymorphic characters, to quasicontinu-ous variation analogous to morphometric data (Wiens,2001).Arguments both for and against the inclusion ofquantitative continuous characters are prevalent in thesystematics literature and are beyond the scope of thisarticle (see Rae, 1998; Swiderski et al., 1998; Thiele,1993). Regardless, various authors have shown thatsuch characters do provide substantial phylogenetic in-formation despite the potential for increased levels ofhomoplasy, and thus remain relevant to empirical sys-tematics (e.g., Campbell and Frost, 1993; Wiens, 1995;WiensandServedio,1998).Severalcodingmethodshavebeen developed for incorporating meristic characters inphylogenetic analysis and dealing with the problem ofpartially overlapping character states across taxa. For bi-nary characters, frequency bins have most often beenused; whereas polymorphic multistate characters havebeen analyzed using majority methods, segment cod-ing, gap coding, gap weighting, step matrices, and var-ious statistical similarity analyses (e.g., Colless, 1980;Mabee and Humphries, 1993; Mickevich and Johnson,1976; Swiderski et al., 1998; Thiele, 1993; Wiens, 1993).Wiens (1998, 2000) and Wiens and Servedio (1997, 1998)evaluated several classes of coding methods and con-cluded that frequency methods were generally most ef-fective. In recent years, two methods that augment andimprove on previous approaches have become widelyused for coding meristic (and other quantitatively de-fined) characters for phylogenetic analysis: step-matrixgap-weighting (SMGW; Wiens, 2001) and general-ized frequency coding (GFC; Smith and Gutberlet,2001).SMGW is an application of step matrices (Wiens,1995) to the gap-weighting method introduced by Thiele(1993). In gap weighting, taxa are assigned states basedon range-standardized mean values of a trait, with thenumber of possible states scaled to the maximum num-ber allowed by the software used to infer phylogenies(e.g.,32statesforPAUP*;Swofford,1993).Gapsbetweenmeans are weighted based on the magnitude of theirdifferences so that larger differences in trait means be-tween taxa translate into larger weights. A limitation ofthe step-matrix approach is that the number of distinctstates is potentially restricted by the software used tobuild phylogenies (e.g., PAUP* only allows 32 states, sodata sets with over 32 taxa would likely not be amenableto SMGW). The purported advantage of SMGW is thatstep matrices allow more fine-grained weighting thansimple gap weighting by increasing the trait range from32 states to 1000 states (the maximum cost betweenstatesinastepmatrixusingPAUP*).Thus,charactersaretreated as approximations of a continuous scale (Wiens,2001).GFC can be viewed as a method that combines ele-ments of both gap weighting (as implemented by Thiele,1993) and the frequency bins method of Wiens (1993).In GFC, each quantitative character is divided into sub-charactersthatcorrespondwitheachcharacterstate.Thefrequency of specimens falling into a given subcharac-ter is described with frequency bins; the overall effectis that cumulative frequency distributions of characterstates per taxa are constructed for each character. A po-tential advantage of GFC is that frequency distributionsare simply translated into phlyogenetically analyzabledata, maximizing information content while eliminat-ing the need for further data manipulation (Smith andGutberlet, 2001). The primary operational difference be-tween these methods is that character states within taxaare coded using estimates of cumulative frequencies of

A strikingly polychromatic new species of Gonatodes (Squamata: Sphaerodactylidae) from northern Venezuela

We describe a new species of diurnal gecko, Gonatodes rozei sp. nov., from tropical and premontane humid forests of north central Venezuela. The new species can be distinguished from other congeners by a combination of large size, subcaudal pattern B (1’1’1’’), three or four lateral scale rows on the digits, males with blue iris, scalation of the gular area, and aspects of color pattern in males and females. The new species is strongly sexually dichromatic and up to four different color morphs are observed in males.

Taxonomy, Hemipenial Morphology, and Natural History of Two Poorly Known Species of Anadia (Gymnophthalmidae) from Northern South America

Abstract Anadia pariaensis Rivas, La Marca, and Oliveros, 1999, and Anadia steyeri Nieden, 1914, are two particularly rare and poorly known lizards described from single specimens. In the case of A. pariaensis, it remains known from the holotype, whereas A. steyeri is known from three additional specimens reported in the literature after the original description of the species. A single new specimen of A. pariaensis and five of A. steyeri, including the first adult males recorded for both species, make possible a more representative description of both species, including descriptions of the hemipenes. Despite both species presenting some similar morphological characteristics, the examination of the hemipenial morphology revealed very different organs. The hemipenis of A. steyeri presents some characteristics that resemble the organs of two species from the Santa Marta Mountain Range in the “bitaeniata-group” (Anadia pulchella and Anadia altaserrania). On the other hand, the hemipenes of A. pariaensis are unique morphologically and cannot be associated with the hemipenes known from other species in the genus. We describe variation within both species, and we comment on possible sexual dimorphism (number and arrangement of the femoral pores), natural history, and the known geographic distribution of the species. We also comment on Anadia bumanguesa Rueda-Almonacid and Caicedo 2004 based on a new specimen, the second known. This species may be a synonym of A. steyeri. Resumen Anadia pariaensis Rivas, La Marca, and Oliveros, 1999 y Anadia steyeri Nieden, 1914, son dos especies raras, escasamente conocidas y descritas con ejemplares únicos. En el caso de A. pariaensis, esta permanece conocida solo por el holotipo; mientras A. steyeri se conoce por cuatro ejemplares señalados en la literatura desde su descripción. En este trabajo, un nuevo ejemplar de A. pariaensis y cinco de A. steyeri, incluyendo los primeros machos adultos registrados para ambas especies hacen posible una descripción detallada, incluyendo la descripción de los hemipenes. A pesar que estas especies presentan algunas características morfológicas similares, el examen de la morfología hemipenial reveló órganos muy diferentes. El hemipene de A. steyeri, presenta algunas características que lo asemejan a los órganos de dos especies del grupo bitaeniata de la sierra de Santa Marta (Anadia pulchella y Anadia altaserrania). Por otra parte, el hemipene de A. pariaensis es único morfológicamente, y no puede ser actualmente asociado con los hemipenes conocidos para otras especies en el género. Se describe la variación intraespecífica, posible dimorfismo sexual (número y disposición de los poros femorales), historia natural y distribución geográfica conocida para ambas especies. Por último, se analiza el estado taxonómico de Anadia bumanguesa Rueda-Almonacid y Caicedo 2004 basado en un nuevo ejemplar disponible (el segundo conocido) y esta nueva información sugiere que la especie podría ser un sinónimo o al menos estar relacionada con A. steyeri.