Patterns of head shape and scutellation in Drymarchon couperi (Squamata: Colubridae) reveal a single species.

Krysko et al. (2016a) used analyses of DNA sequence data to reveal two genetic lineages of Drymarchon couperi. The Atlantic lineage contained specimens from southeastern Georgia and eastern peninsular Florida, and the Gulf Coast lineage contained specimens from western and southern peninsular Florida as well as western Florida, southern Alabama, and southern Mississippi. In a second paper Krysko et al. (2016b) analyzed morphological variation of the two lineages, which allowed them to restrict D. couperi to the Atlantic lineage and to describe the Gulf Coast lineage as a new species, Drymarchon kolpobasileus. This taxonomic discovery was remarkable for such a large, wide-ranging species and was notable for its impact on conservation. Because of population declines, particularly in western Florida, southern Alabama, and southern Mississippi, D. couperi (sensu lato) was listed as Threatened under the Endangered Species Act (United States Fish and Wildlife Service 1978, 2008) and repatriation of the species to areas where it had been extirpated was listed as a priority conservation goal (United States Fish and Wildlife Service 1982, 2008). Such repatriation efforts were attempted in Alabama, Florida, Georgia, and South Carolina, starting in 1977 (Speake et al. 1987), but failed to create viable populations, likely because too few snakes were released at too many sites (Guyer et al. 2019; Folt et al. 2019a). A second attempt at repatriation was started in 2010 and concentrated on release of snakes at a single site in Alabama (Stiles et al. 2013). However, Krysko et al. (2016a) criticized this repatriation effort because it appeared to involve release of D. couperi (sensu stricto) into the geographic region occupied by D. kolpobasileus (as diagnosed in Krysko et al. 2016b).

Taxonomic and conservation implications of population genetic admixture, mito-nuclear discordance, and male-biased dispersal of a large endangered snake, Drymarchon couperi.

Accurate species delimitation and description are necessary to guide effective conservation of imperiled species, and this synergy is maximized when multiple data sources are used to delimit species. We illustrate this point by examining Drymarchon couperi (Eastern Indigo Snake), a large, federally-protected species in North America that was recently divided into two species based on gene sequence data from three loci and heuristic morphological assessment. Here, we re-evaluate the two-species hypothesis for D. couperi by evaluating both population genetic and gene sequence data. Our analyses of 14 microsatellite markers revealed 6-8 genetic population clusters with significant admixture, particularly across the contact zone between the two hypothesized species. Phylogenetic analyses of gene sequence data with maximum-likelihood methods suggested discordance between mitochondrial and nuclear markers and provided phylogenetic support for one species rather than two. For these reasons, we place Drymarchon kolpobasileus into synonymy with D. couperi. We suggest inconsistent patterns between mitochondrial and nuclear DNA are driven by high dispersal of males relative to females. We advocate for species delimitation exercises that evaluate admixture and gene flow in addition to phylogenetic analyses, particularly when the latter reveal monophyletic lineages. This is particularly important for taxa, such as squamates, that exhibit strong sex-biased dispersal. Problems associated with over-delimitation of species richness can become particularly acute for threatened and endangered species, because of high costs to conservation when taxonomy demands protection of more individual species than are supported by accumulating data.

Spatial patterns of the frog Oophaga pumilio in a plantation system are consistent with conspecific attraction.

The conspecific attraction hypothesis predicts that individuals are attracted to conspecifics because conspecifics may be cues to quality habitat and/or colonists may benefit from living in aggregations. Poison frogs (Dendrobatidae) are aposematic, territorial, and visually oriented-three characteristics which make dendrobatids an appropriate model to test for conspecific attraction. In this study, we tested this hypothesis using an extensive mark-recapture dataset of the strawberry poison frog (Oophaga pumilio) from La Selva Biological Station, Costa Rica. Data were collected from replicate populations in a relatively homogenous Theobroma cacao plantation, which provided a unique opportunity to test how conspecifics influence the spatial ecology of migrants in a controlled habitat with homogenous structure. We predicted that (1) individuals entering a population would aggregate with resident adults, (2) migrants would share sites with residents at a greater frequency than expected by chance, and (3) migrant home ranges would have shorter nearest-neighbor distances (NND) to residents than expected by chance. The results were consistent with these three predictions: Relative to random simulations, we observed significant aggregation, home-range overlap, and NND distribution functions in four, five, and six, respectively, of the six migrant-resident groups analyzed. Conspecific attraction may benefit migrant O. pumilio by providing cues to suitable home sites and/or increasing the potential for social interactions with conspecifics; if true, these benefits should outweigh the negative effects of other factors associated with aggregation. The observed aggregation between migrant and resident O. pumilio is consistent with conspecific attraction in dendrobatid frogs, and our study provides rare support from a field setting that conspecific attraction may be a relevant mechanism for models of anuran spatial ecology.

Emendation and new species of Hapalorhynchus Stunkard, 1922 (Digenea: Schistosomatoidea) from musk turtles (Kinosternidae: Sternotherus) in Alabama and Florida rivers.

Hapalorhynchus Stunkard, 1922 is emended based on morphological study of existing museum specimens (type and voucher specimens) and newly-collected specimens infecting musk turtles (Testudines: Kinosternidae: Sternotherus spp.) from rivers in Alabama and Florida (USA). Hapalorhynchus conecuhensis n. sp. is described from an innominate musk turtle, Sternotherus cf. minor, (type host) from Blue Spring (31°5'27.64″N, 86°30'53.21″W; Pensacola Bay Basin, Alabama) and the loggerhead musk turtle, Sternotherus minor (Agassiz, 1857) from the Wacissa River (30°20'24.73″N, 83°59'27.56″W; Apalachee Bay Basin, Florida). It differs from congeners by lacking a body constriction at level of the ventral sucker, paired anterior caeca, and a transverse ovary as well as by having a small ventral sucker, proportionally short posterior caeca, nearly equally-sized anterior and posterior testes, a small cirrus sac, and a uterus extending dorsal to the ovary and the anterior testis. Specimens of Hapalorhynchus reelfooti Byrd, 1939 infected loggerhead musk turtles, stripe-necked musk turtles (Sternotherus peltifer Smith and Glass, 1947), Eastern musk turtles (Sternotherus odoratus [Latreille in Sonnini and Latreille, 1801]), and S. cf. minor. Those of Hapalorhynchus cf. stunkardi infected S. minor and S. odoratus. Sternothorus minor, S. peltifer, and S. cf. minor plus S. minor and S. odoratus are new host records for H. reelfooti and H. cf. stunkardi, respectively. This is the first report of an infected musk turtle from the Coosa and Tallapoosa Rivers (Mobile-Tensaw River Basin), Pensacola Bay Basin, or Apalachee Bay Basin. Sequence analysis of the large subunit rDNA (28S) showed a strongly-supported clade for Hapalorhynchus.

Phylogeography and evolution of the Red Salamander (Pseudotriton ruber).

Phylogeographic studies frequently result in the elevation of subspecific taxa to species given monophyly, or the synonymy of subspecies that are not monophyletic. However, given limited or incongruent datasets, retention of subspecies can be useful to describe hypothesized incipient species or to illustrate interesting biological phenomena driving morphological diversity. Four subspecific taxa have been used to describe largely allopatric geographic variation within the species Pseudotriton ruber, a plethodontid salamander occupying stream and spring habitats across eastern North America: P. r. vioscai occurs in lowland Coastal Plain habitats, while P. r. ruber, P. r. nitidus, and P. r. schencki occupy upland regions in and around the Appalachian Mountains. Pseudotriton ruber co-occurs through its distribution with the aposematic newt Notophthalmus viridescens, and both species are hypothesized to be part of a Müllerian mimicry complex. In this study, we sequenced regions of two mitochondrial (cytochrome b, NADH dehydrogenase subunit 2) and one single copy nuclear protein-coding gene (pro-opiomelanocortin) from individuals sampled across much of the distribution of P. ruber and then used maximum-likelihood and Bayesian phylogenetic inference to test the monophyly of subspecies, reconstruct biogeographic history, and make inferences about morphological evolution. Phylogeographic hypotheses from mitochondrial and nuclear datasets described structure among populations of P. ruber which separated Coastal Plain and upland Appalachian populations, but subspecies were not monophyletic. Biogeographic reconstruction estimated the ancestor of all populations to have occupied and initially diverged in the Coastal Plain during the Pliocene (∼3.6mya), before one lineage subsequently invaded upland areas of Appalachia. Bold bright coloration of high elevation subspecies P. r. nitidus and P. r. schencki appears to have evolved twice. We hypothesize that the Müllerian mimicry complex with N. viridescens and P. ruber may provide a selective mechanism driving the co-evolution of striking bright and dull morphological variation among populations of both species. While P. ruber subspecies were not consistent with our criteria for diagnosing species (monophyly) and therefore could not be elevated to species, we advocate for the retention of subspecies because they describe hypotheses about an incipient species (P. r. vioscai) and how Müllerian mimicry may shape morphological diversity of species.

Evaluating recent taxonomic changes for alligator snapping turtles (Testudines: Chelydridae).

The Alligator Snapping Turtle (Macrochelys temminckii Troost in Harlan 1835, sensu lato) has been historically treated as a single, wide-ranging species, until a recently published paper by Thomas et al. (2014; hereafter Thomas et al.) analyzed variation in morphology and mitochondrial DNA sequence data to describe two new species of Macrochelys: the Apalachicola Alligator Snapping Turtle (Macrochelys apalachicolae Thomas, Granatosky, Bourque, Krysko, Moler, Gamble, Suarez, Leone & Roman 2014) and the Suwannee Alligator Snapping Turtle (Macrochelys suwanniensis Thomas, Granatosky, Bourque, Krysko, Moler, Gamble, Suarez, Leone & Roman 2014). The specific epithet temminckii was retained for populations in drainages from the Yellow River in Alabama and Florida west to the San Antonio River, Texas. Because populations of Macrochelys have been historically exploited by humans (Pritchard 1989) and the life-history strategies of large, long-lived turtles make them susceptible to declines from harvest (Congdon et al. 1994), a sound understanding of species delimitation and richness is critical for the conservation of alligator snapping turtles, especially if the acceptance of a widely distributed species disguises the presence of multiple, smaller-ranged species.