Hershler R.,Smithsonian Institution |
Lang B.K.,One Wildlife Way
Journal of Molluscan Studies | Year: 2010
The Phantom Cave snail (Cochliopa texana), a little-studied rissooidean gastropod that is locally endemic within the lower Pecos River basin (Texas) and currently a candidate for addition to the Federal list of threatened and endangered species, is redescribed and transferred to the hydrobiid genus Pyrgulopsis, based on shell and anatomical characters. Specimens from the type locality (Phantom Lake Spring) and San Solomon Spring are larger than those from East Sandia Spring and also differ somewhat in shell shape and shape of the central cusps of the lateral radular teeth. However genetic (mtCOI, NDI) variation within and among these geographically proximal (6-13 km) populations was slight, providing no basis for the recognition of distinct conservation units of this imperiled species. We also describe Pyrgulopsis ignota n. sp., which was recently discovered in a different part of the lower Pecos River basin and initially confused with the Phantom Cave snail. These two species differ in shell shape, operculum morphology, and form and glandular ornament of the penis. They are also strongly differentiated genetically from each other and from (13) other regional congeners (pairwise sequence divergence >6.3 for both genes). A Bayesian phylogenetic analysis of the COI and NDI dataset indicated that these two snails are not closely related and that P. ignota occupies a basal position relative to other regional congeners. © The Author 2010.
Seidel R.A.,Miami University Ohio |
Lang B.K.,One Wildlife Way |
Berg D.J.,Miami University Ohio
Journal of the North American Benthological Society | Year: 2010
Ecological speciation is the process by which barriers to gene flow arise between populations as a result of ecologically based divergent selection. Environmental salinity has been identified as one of the most important ecological drivers influencing distribution, abundance, and species richness of aquatic organisms. Springs of the northern Chihuahuan Desert vary in salinity and are home to the Gammarus pecos (Crustacea:Amphipoda) species complex. We used field experiments to compare salinity tolerance among 9 amphipod populations from geographically discrete habitats differing in ambient salinities and to calculate salinity response distances among populations. Cluster analysis placed populations into 3 groups corresponding to low, medium, and high ambient salinities. Partial Mantel tests revealed significant positive correlations between salinity tolerance and habitat salinity after controlling for other variables, such as geographic distance and neutral genetic differences. Our results provide evidence that ecological speciation could be occurring among amphipod populations at different springs, as indicated by dissimilar physiological responses that are correlated with differences in ambient spring salinities. Gene flow is restricted among populations, the restriction is reinforced by dispersal barriers between springs, and selection might preserve variants that most effectively tolerate local salinity levels. Gammarus diversification in the northern Chihuahuan Desert is driven by vicariance and isolation, along with local selection and adaptation. © 2010 The North American Benthological Society.
Lang B.K.,One Wildlife Way |
Gilbertson L.H.,Natural History Museum of Los Angeles County
Proceedings of the Biological Society of Washington | Year: 2010
Sonorella painteri, new species is described from the San Luis Mountains, Hidalgo County, New Mexico, U.S.A. Based on comparative studies of shell characters and genitalia, Sonorella hachitana flora Pilsbry & Ferriss, 1915 and Sonorella hachitana peloncillensis Pilsbry & Ferriss, 1915 from southwestern New Mexico are elevated to full species rank.
Liu H.-P.,Metropolitan State University of Denver |
Hershler R.,Smithsonian Institution |
Lang B.,One Wildlife Way |
Davies J.,Metropolitan State University of Denver
Conservation Genetics | Year: 2013
Pyrgulopsis gilae is a small springsnail that is narrowly distributed along the forks of the upper Gila River and currently being managed as a threatened and sensitive species by the State of New Mexico and United States Forest Service, respectively. A previous phylogeographic study of this species based on mitochondrial COI sequences delineated substantial divergence between several populations along the lower and upper reaches of the East Fork Gila River. The present study surveyed COI variation among a larger number of populations across the entire geographic range of P. gilae. Three haplotype groupings were delineated that were congruently resolved as clades by a Bayesian analysis. One of the clades was composed of populations along the lower East Fork and mainstem Gila River and corresponds to P. gilae as originally circumscribed. The other two clades were composed of populations along the Middle Fork and upper East Fork Gila River that were recently referred to P. gilae. These three geographically isolated clades do not share any haplotypes, have significant FST values, and are differentiated from each other by 3.9-6.3 % sequence divergence. Based on this evidence we suggest that the clades represent distinct species and should be managed as separate conservation units pending taxonomic revision of P. gilae. This study provides additional evidence that geographically disjunct subunits of Pyrgulopsis species often represent distinct monophyletic lineages that may warrant formal taxonomic recognition, and thus underscores the importance of fine-scale conservation genetics studies of these imperiled organisms. © 2013 Springer Science+Business Media Dordrecht (outside the USA).
PubMed | Smithsonian Institution, Metropolitan State University of Denver and One Wildlife Way
Type: | Journal: ZooKeys | Year: 2014
We describe two new species of springsnails (genus Pyrgulopsis) for populations from the middle Fork and upper East Fork of the Gila River Basin (New Mexico) that had been previously identified as P. gilae. We also restrict P. gilae to its originally circumscribed geographic range which consists of a short reach of the East Fork Gila River and a single spring along the Gila River (below the East Fork confluence). These three species form genetically distinct lineages that differ from each other by 3.9-6.3% for mtCOI and 3.7-8.7% for mtNDI (the latter data were newly obtained for this study), and are diagnosable by shell and penial characters. Collectively the three species form a strongly supported clade that is distinguished from other congeners by the unique presence of two glandular strips on the dorsal surface of the penial filament. These findings suggest that the conservation status of P. gilae, which was recently removed from the list of candidates for listing as endangered or threatened by the United States Fish and Wildlife Service, should be revisited and that the two new species may also merit protective measures given their narrow geographic ranges.