Turtles of the clade Pan-Testudinoidea have a rich fossil record in North America, including the Caribbean, ranging from the late Paleocene to the Holocene. All earlier reports cannot be substantiated herein. The earliest members of this clade probably immigrated in multiple waves from Asia. Current phylogenies of crown Testudinoidea recognize four primary clades: Pan-Emydidae, Pan-Geoemydidae, Pan-Testudinidae, and the lineage leading to Platysternon megacephalum. An updated global phylogeny allows attribution of fossils to these lineages with confidence that allows the discernment of new diversity trends and biogeographic patterns. The diversity of North American Pan-Testudinidae increased consistently throughout the Cenozoic and reached its peak in the early Miocene. The extinction of many testudinids at the end of the Pleistocene, however, decreased tortoise diversity toward its extant levels. The diversity of North American Pan-Emydidae and Pan-Geoemydidae shows opposite patterns. Pan-Emydidae are remarkably diverse today, but their diversity was low in the Eocene and only increased dramatically from the Oligocene and onwards. Pan-Geoemydidae, on the other side, were diverse in the late Paleocene to Eocene, but their diversity decreases to their extremely low present levels starting with the Oligocene. A taxonomic review of 191 named North and Central American pan-testudinoid taxa finds 57 nomina valida, 69 nomina invalida, 64 nomina dubia, and 1 nomen nudum.

We provide a description of the Blueface Darter, Etheostoma cyanoprosopum, which is distributed in the upper Sipsey Fork of the Mobile Basin and the upper portion of the Bear Creek system in the Tennessee River Drainage. The distinctiveness of Etheostoma cyanoprosopum is assessed through analysis of morphological variation and molecular phylogenetic diversity within the Etheostoma zonistium species complex. In addition to analyzing disparity of morphometric and meristic traits, we present phylogenetic analyses of a mitochondrial gene and two nuclear genes and identify genetic clusters through analysis of 25 microsatellite loci. In the mitochondrial DNA (mtDNA) gene tree, Etheostoma cyanoprosopumis resolved as the sister lineage to a clade containing all other species of the Etheostoma zonistium complex. Etheostoma zonistium is paraphyletic with respect to both Etheostoma pyrrhogaster and Etheostoma cervus, which do not resolve as sister species in the mtDNA gene tree. The two nuclear gene trees are much less resolved, but the S7 ribosomal protein intron 1 (S7) gene tree resolves Etheostoma cyanoprosopum and all sampled populations of Etheostoma zonistium as a clade with strong Bayesian posterior node support. Etheostoma cyanoprosopum is morphologically differentiated from Etheostoma zonistium by a shallower body, a more elongate nape, a higher number of lateral line scales, a higher number of transverse scale rows, and differences in coloration.

Percina apina, the Tennessee Logperch, is described as a new species endemic to Tennessee and distributed in the Duck River system and Whiteoak Creek. The earliest collection records for Percina apina date to 1971 and the species was identified as Percina burtoni, the Blotchside Logperch. A phylogenetic analysis of mitochondrial DNA (mtDNA) published in 2006 showed that populations identified as Percina burtoni in the Duck River system and Whiteoak Creek were a new and undescribed species. In this study, we test the hypothesis that Percina burtoni is composed of multiple species through analyses of mtDNA, nuclear genetic variation, and traditional meristic trait morphology. Our analyses of morphological divergence, nuclear genotypes, mtDNA gene trees, and comparisons with other sister species pairs of logperches confirm the distinctiveness of Percina apina. Morphologically, Percina apina is distinguished from Percina burtoni through higher average numbers of lateral line scales (93.1 versus 89.9); pored lateral line scales (91.6 versus 88.8); rows of transverse scales (38.1 versus 33.6); and scales around the caudal peduncle (36.2 versus 33.5). The two species also differ in patterns of pigmentation; the lateral blotches in Percina apina are typically wider than high, whereas the blotches tend to be higher than wide in Percina burtoni. We recommend that future species descriptions of North American freshwater fishes leverage available genetic resources and include molecular phylogenetic assessments in analyses of taxon distinctiveness. In addition, we advocate the deposition of morphological data used in species descriptions to online data repositories to ensure that other researchers are able to evaluate and modify hypotheses of species delimitations.

Placobdella nuchalis Sawyer and Shelley, 1976 was originally described based on specimens from Four Hole Swamp (type locality) and a stream near Ashepoo River in South Carolina, USA, and Merchant's Millpond and Nine Mile Creek in North Carolina, USA. Leeches collected during August 2014 and August 2015 from Four Hole Swamp (type locality) and Merchant's Millpond (paratype locality) facilitated a redescription and molecular characterization of Placobdella nuchalis. Two additional specimens of Placobdella nuchaliswere collected on 10 August 2014 from Nassawango Creek, Maryland, USA, representing a state distribution record. Placobdella nuchalis has a brownish green dorsum with a dark medial line interrupted three times by yellow-cream spots, a pair of paralateral rows of unpigmented papillae with adjacent dark green papillae, and a distinct discoid head. Molecular comparison of cytochrome c oxidase subunit I (CO-I) sequence data from a specimen of Placobdella nuchalis from Four Hole Swamp (type locality) revealed a 94.5% similarity to a specimen collected from Merchant's Millpond (paratype locality) and 14.2% to 17.5% differences among other species of Placobdella.

The Late Jurassic (Oxfordian to Tithonian) fossil record of Europe and South America has yielded a particularly rich assemblage of aquatic pan-cryptodiran turtles that are herein tentatively hypothesized to form a monophyletic group named Thalassochelydia. Thalassochelydians were traditionally referred to three families, Eurysternidae, Plesiochelyidae, and Thalassemydidae, but the current understanding of phylogenetic relationships is insufficient to support the monophyly of either group. Given their pervasive usage in the literature, however, these three names are herein retained informally. Relationships with marine turtles from the Cretaceous have been suggested in the past, but these hypotheses still lack strong character support. Thalassochelydians are universally found in near-shore marine sediments and show adaptations to aquatic habitats, but isotopic evidence hints at a broad spectrum of specializations ranging from freshwater aquatic to fully marine. A taxonomic review of the group concludes that of 68 named taxa, 27 are nomina valida, 18 are nomina invalida, 18 are nomina dubia, and 5 nomina oblita.