Browsing by Author "Schargel, Walter E."
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item An enigmatic new snake from cloud forest of the Península de Paria, Venezuela (Colubridae, genus Taeniophallus?). American Museum novitates ; no. 3484(New York, NY : American Museum of Natural History, 2005) Schargel, Walter E.; Rivas Fuenmayor, Gilson; Myers, Charles W.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.Item Morphological extremes--two new snakes of the genus Atractus from northwestern South America (Colubridae, Dipsadinae) ; American Museum novitates, no. 3532(New York, NY : American Museum of Natural History, 2006) Myers, Charles W.; Schargel, Walter E.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 other congeners that attain lengths > 700 mm. The only known specimen has an azygous frontonasal scale that is atypical of colubrids (but is not an obvious aberrancy). Atractus gigas comes from 1900 m elevation on the Pacific versant of the Andes (Bosque Protector Râio Guajalito, Pichincha, Ecuador.Item Phylogenetic systematics of dart-poison frogs and their relatives (Amphibia, Athesphatanura, Dendrobatidae). Bulletin of the AMNH ; no. 299(New York, NY : American Museum of Natural History, 2006) Grant, Taran, 1972-; Frost, Darrel R.; Caldwell, Janalee P.; Gagliardo, Ron; Haddad, Célio F.B.; Kok, Philippe J.R.; Means, D. Bruce; Noonan, Brice P.; Schargel, Walter E.; Wheeler, Ward.The known diversity of dart-poison frog species has grown from 70 in the 1960s to 247 at present, with no sign that the discovery of new species will wane in the foreseeable future. Although this growth in knowledge of the diversity of this group has been accompanied by detailed investigations of many aspects of the biology of dendrobatids, their phylogenetic relationships remain poorly understood. This study was designed to test hypotheses of dendrobatid diversification by combining new and prior genotypic and phenotypic evidence in a total evidence analysis. DNA sequences were sampled for five mitochondrial and six nuclear loci (approximately 6,100 base pairs [bp]; å[arithmetic mean] = 53,740 bp per terminal; total dataset composed of approximately 1.55 million bp), and 174 phenotypic characters were scored from adult and larval morphology, alkaloid profiles, and behavior. These data were combined with relevant published DNA sequences. Ingroup sampling targeted several previously unsampled species, including Aromobates nocturnus, which was hypothesized previously to be the sister of all other dendrobatids. Undescribed and problematic species were sampled from multiple localities when possible. The final dataset consisted of 414 terminals: 367 ingroup terminals of 156 species and 47 outgroup terminals of 46 species. Direct optimization parsimony analysis of the equally weighted evidence resulted in 25,872 optimal trees. Forty nodes collapse in the strict consensus, with all conflict restricted to conspecific terminals. Dendrobatids were recovered as monophyletic, and their sister group consisted of Crossodactylus, Hylodes, and Megaelosia, recognized herein as Hylodidae. Among outgroup taxa, Centrolenidae was found to be the sister group of all athesphatanurans except Hylidae, Leptodactyidae was polyphyletic, Thoropa was nested within Cycloramphidae, and Ceratophryinae was paraphyletic with respect to Telmatobiinae. Among dendrobatids, the monophyly and content of Mannophryne and Phyllobates were corroborated. Aromobates nocturnus and Colostethus saltuensis were found to be nested within Nephelobates, and Minyobates was paraphyletic and nested within Dendrobates. Colostethus was shown to be rampantly nonmonophyletic, with most species falling into two unrelated cis- and trans-Andean clades. A morphologically and behaviorally diverse clade of median lingual process-possessing species was discovered. In light of these findings and the growth in knowledge of the diversity of this large clade over the past 40 years, we propose a new, monophyletic taxonomy for dendrobatids, recognizing the inclusive clade as a superfamily (Dendrobatoidea) composed of two families (one of which is new), six subfamilies (three new), and 16 genera (four new). Although poisonous frogs did not form a monophyletic group, the three poisonous lineages are all confined to the revised family Dendrobatidae, in keeping with the traditional application of this name. We also propose changes to achieve a monophyletic higher-level taxonomy for the athesphatanuran outgroup taxa. Analysis of character evolution revealed multiple origins of phytotelm-breeding, parental provisioning of nutritive oocytes for larval consumption (larval oophagy), and endotrophy. Available evidence indicates that transport of tadpoles on the dorsum of parent nurse frogs--a dendrobatid synapomorphy--is carried out primitively by male nurse frogs, with three independent origins of female transport and five independent origins of biparental transport. Reproductive amplexus is optimally explained as having been lost in the most recent common ancestor of Dendrobatoidea, with cephalic amplexus arising independently three times.Item Supplemental Material for 'Phylogenetic systematics of dart-poison frogs and their relatives (Amphibia, Athesphatanura, Dendrobatidae). (Bulletin of the AMNH ; no. 299)'(2006) Grant, Taran, 1972-; Frost, Darrel R.; Caldwell, Janalee P.; Gagliardo, Ron; Haddad, Célio F. B.; Kok, Philippe J. R.; Means, D. Bruce; Noonan, Brice P.; Schargel, Walter E.; Wheeler, Ward.Supplemental Material for 'Phylogenetic systematics of dart-poison frogs and their relatives (Amphibia, Athesphatanura, Dendrobatidae). (Bulletin of the AMNH ; no. 299)' - http://hdl.handle.net/2246/5803