Encontro casual na região central do Texas fornece informações sobre a ecologia da estivação de Siren nettingi (Caudata: Sirenidae)

Siren spp. costumam ser vertebrados dominantes nas áreas úmidas que ocupam e são conhecidas por estivar quando essas áreas úmidas secam. Considerações práticas limitam as observações in situ de indivíduos em estivação. Em 12 de outubro de 2021, descobrimos por acaso um agregado em estivação de Siren nettingi no condado de Bastrop, Texas, Estados Unidos. Essas salamandras foram escavadas em solo compacto e rochoso adjacente a uma estrada de caliche, em profundidades que variavam entre ~0,2 e 1,5 m. A vegetação dominante nesse local incluía Ulmus crassifolia, Persicaria sp. e várias espécies de gramíneas. Recuperamos 140 indivíduos, dos quais sete foram resgatados e 133 foram capturados vivos. Medimos 115 deles quanto ao comprimento rostro-cloacal (SVL) e observamos que o agregado era dominado por jovens. Estimamos uma densidade de estivação de 2,33 indivíduos/m2 que é comparável às densidades estimadas para populações sem estivação. No entanto, como não houve monitoramento para esse estudo, provavelmente tenha ocorrido um evento de mortalidade em massa. Portanto, sugerimos que a construção de estradas no habitat preferido seja considerada uma ameaça às populações dessas salamandras.Siren spp. are often dominant vertebrates in the wetlands they occupy and are known to estivate when such wetlands dry up. Practical considerationslimit in-situ observations of estivating individuals. On 12 October 2021, we incidentally discovered an estivating aggregate of Siren nettingi in Bastrop County, Texas, USA. These salamanders were excavated from compact, rocky soil adjacent to a caliche road, at depths that ranged between ~0.2 to 1.5 m. The dominant vegetation at this site included Ulmus crassifolia, Persicaria sp., and various grass species. We recovered 140 individuals of which seven were salvaged and 133 were captured live. We measured 115 of these for snout–vent length (SVL) and observed the aggregate was predominated by juveniles. We estimated an estivation density of 2.33 sirens/m2 that is comparable to densities estimated for non-estivating populations. However, in-lieu of monitoring that was in place for this study, we expect a mass mortality event would have likely occurred. We therefore suggest that roadway construction in preferred habitat be considered as a threat to siren populations

Mitochondrial sequence data reveal population structure within Pustulosa pustulosa

Unionid mussels are among the most imperiled group of organisms in North America, and Pustulosa pustulosa is a freshwater species with a relatively wide latitudinal distribution that extends from southern Ontario, Canada, to Texas, USA. Considerable morphological and geographic variation in the genus Pustulosa (formerly Cyclonaias) has led to uncertainty over species boundaries, and recent studies have suggested revisions to species-level classifications by synonymizing C. aurea, C. houstonensis, C. mortoni, and C. refulgens with C. pustulosa (currently P. pustulosa). Owing to its wide range and shallow phylogenetic differentiation, we analyzed individuals of P. pustulosa using mitochondrial DNA sequence data under a population genetics framework. We included 496 individuals, which were comprised of 166 samples collected during this study and 330 additional sequences retrieved from GenBank. Pairwise ΦST measures based on ND1 data suggested there may be up to five major geographic groups present within P. pustulosa. Genetic differentiation between regions within Texas was higher compared to populations from the Mississippi and Great Lakes populations, which may reflect differences in historical connectivity. Mitochondrial sequence data also revealed varying demographic histories for each major group suggesting each geographic region has also experienced differential population dynamics in the past. Future surveys should consider exploring variation within species after phylogeographic delimitation has been performed. In this study, we begin to address this need for freshwater mussels via the P. pustulosa system