Threatened across much of their range, Timber Rattlesnakes (Crotalus horridus) exhibit patterns of genetic diversity that are shaped by movement and aspects of their environment in ways that may foster or constrain conservation. We combine movement data with nuclear and mitochondrial population genetic data to understand the population structure and patterns of gene flow for snakes in four overwintering sites (hibernacula) in central Pennsylvania. Our analyses show that hibernacula separated by only a few kilometers can maintain genetic structure along with high gene flow. Female spatial use rarely overlapped with individuals from adjacent hibernacula, whereas male spatial use typically did overlap with individuals from adjacent hibernacula. This study offers new evidence for how asymmetry in gene flow (with males responsible for inter-hibernaculum matings) shapes Timber Rattlesnake population genetics.

A new species of Gigantactis is described from a single female collected from the eastern North Pacific. As with others of this genus, this species is distinguished by its unique luring apparatus, most obviously through the presence of a relatively short illicium, bearing a secondary escal-like appendage.

A new species of Nannocharax is described from the Luongo and Kalungwishi Rivers, tributaries of the Luapula River in the northeastern region of Zambia. The new species differs from its congeners by a combination of characters, such as the body coloration pattern formed by a series of one-scale-wide vertical bars, a small caudal-peduncle spot surrounded by a light clear area at the base of the middle caudal-fin rays, and a low number of scales in the circumpeduncular series and lateral line series. The new species is also distinguished from other members of the Nannocharax multifasciatus species-group by genetic distances ranging from 10.3% to 11.6% with DNA barcoding. Likewise, distance and coalescent molecular species delimitation approaches recovered the new species as an independent operational taxonomic unit. Newly generated hypotheses of phylogenetic relationships based on maximum likelihood and Bayesian inference for the new taxon are provided.

Species-level diversification (speciation) results from the evolution of reproductive isolation. When reproductive isolation is intrinsic (independent of ecological context), speciation is thought to be irreversible. Intrinsic reproductive isolation manifests as a reduction in hybrid fitness due to Dobzhansky-Muller incompatibilities, and can render hybrids sterile or inviable. During fieldwork in western Cuba, I identified abnormal-looking individuals with small gonads within an assemblage of Anolis. I hypothesized that such individuals were interspecific hybrids and predicted a phenotypic distinctness and lower reproductive fitness. I evaluated my predictions by comparing putative hybrids with candidate parental species in external phenotypic traits and gonadal indicators of reproductive fitness. I found that putative hybrids were phenotypically distinct and did not produce sperm cells, suggesting that hybrid sterility may be important in maintaining species boundaries in this ecologically complex system.

A new species of the hagfish genus Eptatretus (Myxinidae) is described based on a single female specimen, 296 mm total length, collected from the Bahamas, off southern Grand Bahama Island, Northwest Providence Channel, between depths of 560 and 591 m. The new species is distinguished from its congeners by having five pairs of well-spaced gill apertures arranged in a nearly straight line, a 3/2 multicusp pattern of teeth, 54 total tooth cusps, 18 prebranchial slime pores, 4–5 branchial pores, 47–49 trunk pores, 82–85 total pores, and two bilaterally symmetrical nasal-sinus papillae. We also discuss the taxonomy of a specimen from Suriname provisionally named as Eptatretus sp. by Shimizu. A distribution map and an updated identification key for all species of Eptatretus and Rubicundus from the western Atlantic are provided.

The Gopher Tortoise (Gopherus polyphemus) is a keystone species endemic to the Coastal Plain ecoregion of the southeastern United States. Gopher Tortoises excavate extensive burrows that are used by over 60 vertebrate and 300 invertebrate species. Our understanding of burrow commensals has generally been limited to Longleaf Pine (Pinus palustris) savanna and xeric uplands and shrublands, excluding private, working pine (Pinus spp.) forests that are known to harbor tortoise populations. Therefore, we used passive infrared wildlife cameras to document vertebrate burrow commensals and evaluate differences in composition across burrow classifications (i.e., abandoned, active, and inactive) within a private, working Loblolly Pine (Pinus taeda) forest located in the Upper Coastal Plain ecoregion of Georgia, USA. Our study showed that the composition of vertebrate commensals did not differ across abandoned, active, or inactive tortoise burrows, indicating that burrows, regardless of classification, may provide a similar suite of resources (e.g., refugia, forage) to vertebrate commensals. Also, we observed numerous species using burrows that typically occur in other landscapes with known tortoise populations (e.g., Longleaf Pine savannah). We encourage continued monitoring of tortoise burrows and other potential refugia within working forests to better understand how these structures contribute to species abundance and persistence within these forests.