A combined morphological and molecular phylogeny of the genus Chironius Fitzinger, 1826 (Serpentes: Colubridae)

Chironius is one of the most speciose genera of the South American colubrid snakes. Although the genus represents a well‐known radiation of diurnal racers, its monophyly, affinities with other Neotropical colubrid genera, and intrageneric relationships are open questions. Here, we present a phylogenetic analysis of Chironius based on a data matrix that combines one nuclear (c‐mos) and two mitochondrial (12S and 16S rRNA) genes with 37 morphological characters derived from scutellation, skull, and hemipenial features. Phylogenetic relationships were inferred using maximum parsimony (MP) and maximum likelihood (ML). Our combined morphological and molecular analyses strongly support the monophyly of the genus Chironius and its sister‐group relationship with a clade formed by the genera Dendrophidion and Drymobius. Phylogenetic relationships within the genus Chironius is still controversial, although five clades are retrieved with medium to strong support. © 2014 The Linnean Society of London     

介绍一种固定蛇类标本外翻半阴茎的制作方法

蛇类半阴茎的形态特征在蛇类分类、进化和系统发育等研究中具有重要价值.本文介绍了一种改进的固定蛇类标本外翻半阴茎的制作方法.     

Extrabuccal infralabial secretion outlets in Dromophis,Mimophis and Psammophis species (Serpentes,Colubridae, Psammophiini). A probable substitute for 'self-rubbing' and cloacal scent gland functions,and a cue for a taxonomic account

Extrabuccal infralabial secretion outlets (ILOs), periodically absent and heretofore non-described, have been found in nineteen species representing three of the eight psammophine snake genera. These infralabial outlets are thought to be non-existent in the other five genera. A few psammophines representing four genera, among which three of the five without ILOs, are characterised by their 'self-rubbing' behaviour, for which they employ an external narial valve bearing a secretion outlet of a special nasal gland. Such a valve is here reported for representatives of all eight genera. It is proposed that all psammophines perform self-rubbing to enable subsequent chemical marking of substrate and conspecific individuals. The newly found infralabial outlets, however, serve for direct chemical marking of conspecifics. This direct marking seems to substitute for a function of both the special nasal gland and the cloacal scent glands during social activity of the snakes in trees or shrubs. This hypothesis and the relationship of the observed traits with the presumed advantages of a thin and short hemipenis are discussed. A taxonomic implication is suggested.     

From the inside out: Discovery of a new genus of threadsnakes based on anatomical and molecular data,with discussion of the leptotyphlopid hemipenial morphology

The systematics of Leptotyphlopidae is historically controversial mostly due to their conserved external morphology in comparison with other snakes. However, recent studies have stressed that anatomical data might be informative for clarifying the leptotyphlopid taxonomy and evolution. We erect a new genus to accommodate Leptotyphlops collaris based on evidence from osteology, hemipenial morphology, and molecular data. We also provide expanded data regarding the intraspecific variation based on additional specimens collected in field trips and literature data, performing detailed comparisons among the new genus and all other New World leptotyphlopids. The new genus is distinguished from other leptotyphlopids by its unique hemipenial morphology and its exclusive combination of osteological and external morphology characters, with molecular data also supporting the new generic arrangement. We also provide a comprehensive discussion of the hemipenial morphology for the subfamily Epictinae based on literature and novel data gathered herein.     

Resurrecting embryos of the tuatara,Sphenodon punctatus,to resolve vertebrate phallus evolution

The breadth of anatomical and functional diversity among amniote external genitalia has led to uncertainty about the evolutionary origins of the phallus. In several lineages, including the tuatara, Sphenodon punctatus, adults lack an intromittent phallus, raising the possibility that the amniote ancestor lacked external genitalia and reproduced using cloacal apposition. Accordingly, a phallus may have evolved multiple times in amniotes. However, similarities in development across amniote external genitalia suggest that the phallus may have a single evolutionary origin. To resolve the evolutionary history of amniote genitalia, we performed three-dimensional reconstruction of Victorian era tuatara embryos to look for embryological evidence of external genital initiation. Despite the absence of an intromittent phallus in adult tuataras, our observations show that tuatara embryos develop genital anlagen. This illustrates that there is a conserved developmental stage of external genital development among all amniotes and suggests a single evolutionary origin of amniote external genitalia.