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Contribution to the herpetofauna of the Venezuelan Guayana. Part I. A Data Base
... The other species suggested to be reproductively bimodal is He. angulatus, with some well-documented reports of egg-laying (e.g., Ford and Ford, 2002; Gorzula and Señaris, 1998; Rossman, 1973), but at least one record of viviparity (Rossman, 1984). A preserved female collected in Peru contained seven apparently fully developed young in the uterus without eggshell and residual yolk (Rossman, 1984). ...
... Variation in ventral coloration occurs within populations and in different areas (e.g., Ford and Ford, 2002; Starace, 2013). Diagnostic pholidosis characters (e.g., number of dorsal scale rows in mid-body, ventral scales, and cephalic scales) seem to be similar between individuals from areas where oviparity occurs (e.g., Venezuela, French Guiana, north and north-eastern Brazil: Cunha and Nascimento, 1993; Gorzula and Señaris, 1998; Schmidt and Inger, 1951; Starace, 2013; H.B. Braz; pers. obs.) and individuals from areas where viviparity occurs (e.g., Peru, Colombia, central and eastern Brazil: Frota, 2005; Lehr, 2002; Pérez-Santos and Moreno, 1988; H.B. Braz, pers. ...
... Long incubation periods suggest that eggs are laid with embryos at early stages, whereas short incubation periods suggest eggs are laid with embryos at later stages. Incubation duration in oviparous He. angulatus was 109 days in Venezuela (Gorzula and Señaris, 1998), 39-45 days in Trinidad (Ford and Ford, 2002), and 17-18 days in Colombia (Rossman, 1973). In the latter, well-developed embryos were readily visible through the shells at oviposition (Rossman, 1973). ...
Viviparity has evolved at least 115 times in squamates and these multiple origins have raised a series of functional and evolutionary questions. Ideally, testing evolutionary hypotheses on squamate viviparity requires focusing on closely related taxa that exhibit both reproductive modes. South American water snakes of the tribe Hydropsini (genera Hydrops, Pseudoeryx, and Helicops) are a potential model system for studying the evolution of viviparity. However, available information about reproductive modes in this group is often confusing and contradictory. Herein, we identify the reproductive modes of the Hydropsini species by combining original data taken from both museum and live specimens with a critical review of the published literature. In addition, we mapped the reproductive modes on different phylogenetic hypotheses to identify origins of viviparity. The genus Hydrops is exclusively oviparous. Contrary to previous suggestions, we found Pseudoeryx plicatilis to be oviparous, and available evidence suggests that females of the species remain with eggs throughout incubation. Our results show that reproductive mode varies only in the genus Helicops. Two Helicops species are oviparous and eight species are viviparous. Interestingly, we also found that one species (Helicops angulatus) exhibits both reproductive modes. Intraspecific variation in reproductive mode is a rare phenomenon in squamates, and H. angulatus is the only snake species in which reproductive bimodality has been confirmed. H. angulatus is oviparous from northern to mid-eastern and north-eastern South America, and viviparous from north-western to mid-western South America. The allopatric distribution of oviparous and viviparous forms of H. angulatus does not support the hypothesis of facultative changes in the reproductive mode. Geographic variation in the embryonic stage at oviposition is likely to occur in H. angulatus. Ancestral state reconstructions suggest that oviparity is plesiomorphic in Hydropsini, as well as in the bimodal genus Helicops, and that viviparity has evolved independently at least three times in Helicops. We argue that the water snakes of the tribe Hydropsini (and more importantly, the genus Helicops and the bimodal H. angulatus) are an excellent model to test hypotheses on the evolution of squamate viviparity.
... We do not doubt that several other summits and slopes of tepuis will yield surprises. For example, in the Serranía de la Neblina the preliminary account reported seven undescribed species (McDiarmid & Paolillo, 1988), and Gorzula & Señaris (1998) mentioned Eleutherodactylinae series A from Cerro Guanay (estado Bolivar), and Eleutherodactylinae series B, from several tepui summits in Estado Bolívar. ...
... As noted, only a few tepuis are known to be inhabited by Eleutherodactylus: Yavi (Myers & Donnelly, 1996), Tamacuari (Myers & Donnelly, 1997), Yutajé (Myers & Donnelly, 2001 ), Guanay, Corocoro, Aprada-tepui, Auyántepui , Terekyurén (Murisipán)-tepui, Yuruaní-tepui (Gorzula & Señaris, 1998), Neblina (McDiarmid & Paolillo, 1988) and Ayanganna (Guyana) (R. MacCulloch, pers. comm). ...
Se describe una nueva especie de Eleutherodactylus del grupo unistrigatus de la cima del Cerro Marahuaka en Amazonas, Venezuela. La nueva especie se distingue fácilmente entre las otras espe-cies de Eleutherodactylus del sur de Venezuela por su tímpano indistinto, ausencia de calcares, tubérculos metatarsales indistintos, piel dorsal lisa, dedos libres, con rebordes cutáneos presentes pero poco destacados, coloración del iris y general del cuerpo. Se provee un resumen histórico de los Eleutherodactylus del sur de Venezuela. Abstract A new species of Eleutherodactylus of the unistrigatus species group is described from the summit of Cerro Marahuaka, Estado Amazonas, Venezuela,. The new species is easily distinguished from other southern Venezuelan Eleutherodactylus by its indistinct tympanum, absence of calcars, indistinct metatarsal tubercles, smooth dorsal skin, weak fringes on fingers and toes, lack of basal webbing, iris colour pattern and overall body coloration. A historical resumé of southern Venezuelan Eleutherodactylus is provided.
... as currently recognized are recovered non-reciprocally monophyletic (Fig. 3). Our molecular phylogeny also reveals the occurrence of five candidate species (sensu Padial et al. 2010) that have been misidentified for more than a decade as S. ginesi (two candidate species) or S. satelles (three candidate species) (e.g., Señaris et al. 1997; Gorzula and Señaris 1999). Preliminary morphological analyses (in progress) indicate a few, sometimes subtle, morphological characters allowing discrimination among these candidate cies and S. ginesi and S. satelles. ...
It has been suggested that the inability to migrate in response to climate change is a key threat to tepui summit biota. Tepui summit organisms might thus seriously be threatened by global warming, and there is an urgent need to accurately evaluate their taxonomic status and distributions. We investigated phylogenetic relationships among several populations of Stefania ginesi and S. satelles, two endemic species reported from some isolated tepui summits, and we examined their IUCN conservation status. Molecular phylogenetic analysis and preliminary morphological assessment indicate that both species are actually restricted to single tepui summits and that five candidate species are involved under these names. We advocate upgrading the conservation status of S. ginesi from Least Concern to Endangered, and that of S. satelles from Near Threatened to Endangered.
... In our first paper (MacCulloch and Reynolds 2012) we briefly review some recent pertinent literature on the amphibians and reptiles of the Guiana Shield Region (Starace 1998; Gorzula and Señaris 1999; Lescure and Marty 2000; Reynolds et al. 2001; Avila-Pires 2005; Donnelly et al. 2005, McDiarmid and Donnelly 2005; Señaris and MacCulloch 2005; MacCulloch et al. 2007, Kok and Kalamandeen 2008, MacCulloch and Lathrop 2009) and report on the herpetofauna at two upland sites in the southern foothills of the Pakaraima Mountains in west-central Guyana. In this companion paper, we report the results from two separate collecting trips to the lowland forests near Baramita. ...
We provide an initial checklist of the herpetofauna of Baramita, a lowland rainforest site in the Northwest Region of Guyana. Twenty-five amphibian and 28 reptile species were collected during two separate dry-season visits. New country records for two species of snakes are documented, contributing to the knowledge on the incompletely known herpetofauna of Guyana.
How innovations such as vision, flight and pregnancy evolve is a central question in evolutionary biology. Examination of transitional (intermediate) forms of these traits can help address this question, but these intermediate phenotypes are very rare in extant species. Here we explore the biology and evolution of transitional forms of pregnancy that are midway between the ancestral state of oviparity (egg‐laying) and the derived state, viviparity (live birth). Transitional forms of pregnancy occur in only three vertebrates, all of which are lizard species that also display intraspecific variation in reproductive phenotype. In these lizards (Lerista bougainvillii, Saiphos equalis, and Zootoca vivipara), geographic variation of three reproductive forms occurs within a single species: oviparity, viviparity, and a transitional form of pregnancy. This phenomenon offers the valuable prospect of watching ‘evolution in action’. In these species, it is possible to conduct comparative research using different reproductive forms that are not confounded by speciation, and are of relatively recent origin. We identify major proximate and ultimate questions that can be addressed in these species, and the genetic and genomic tools that can help us understand how transitional forms of pregnancy are produced, despite predicted fitness costs. We argue that these taxa represent an excellent prospect for understanding the major evolutionary shift between egg‐laying and live birth, which is a fundamental innovation in the history of animals.
Ambos apéndices se refieren a la descripción de nuevas especies de serpientes. En el primer apéndice se describe una nueva serpiente del género Atractus del Parque Nacional Yacambú, Lara, Venezuela. Entre tanto, el segundo apéndice se dedica a la descripción de una nueva serpiente Epictia del Tepui Guaquinima, Bolívar, Venezuela; adicionalmente se analiza el género a lo largo de su distribución neotropical.
We report the herpetofauna of two neighboring upland locations in west-central Guyana. Twenty amphibian and 24 reptile species were collected. Only 40% of amphibians and 12.5% of reptiles were collected in both locations. This is one of the few collections made at upland (750-800 m) locations in the Guiana Shield.
Article 31 of the Code allows to form a species or subspecies from a personal name, using a nomen in the genitive case. Some zoologists have construed this rule as meaning that such nomina should always end in -i if dedicated to a man, in -ae if dedicated to a woman, in -arum to several women and in -arum to several persons including at least one man. They therefore proposed emendations to those nomina which they considered ill-formed under this interpretation. A detailed analysis shows that the latter is wrong, and that the original spelling (including its ending) of any new nomen based on a personal name should not be modified (except possibly in a few very rare cases). New spellings proposed by some authors for the reasons above are unjustified emendations, with their own authors and dates. Some problems related to homonymy in nomina based on personal names are also discussed. In conclusion, I propose a rewording of a few Articles of the Code to remedy some of the ambiguities pointed to by this analysis.
The first voucher specimen in a reference collection of Typhlonectes compressicauda (Duméril y Bibron 1841) (Gymnophiona: Typhlonectidae), was obtained in the Colombian Amazon, confirming previous observations in the region. Additional information obtained provide additional knowledge about their life history and in particular physical and chemical habitat features
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