Morphology and Phylogeny of the Studfish Clade, Subgenus Xenisma (Teleostei: Cyprinodontiformes)

Phylogenetic relationships within the studfish clade, subgenus Xenisma, were elucidated using parsimony analysis of 21 morphological transformation series, primarily osteology and external morphology. The analysis supports monophyly of subgenus Xenisma and the studfishes sensu strictu (Fundulus bifax, Fundulus catenatus, and Fundulus stellifer). Fundulus julisia and Fundulus albolineatus are recognized as sister taxa and together are recognized as sister to the F. bifax, F. catenatus, and F. stellifer clade. Contrary to a previous allozyme study of the subgenus, Fundulus rathbum is recognized as sister to a monophyletic group composed of all other Xenisma species. This relationship is biogeographically consistent with the vicariant pattern previously demonstrated within darters of the subgenus Percina and suckers of the genus Hypentelium. The biogeography of the rest of subgenus Xenisma is complex and the sister-group relationship between F. catenatus and F. bifax is recognized as anomalous when compared to other Mississippi-Mobile basin biogeographic relationships in North American fishes

New species of Jenynsia (Teleostei: Cyprinodontiformes) from southern Brazil and its phylogenetic relationships

A new species of Jenynsia from southern Brazil is described. Jenynsia weitzmani n. sp. from the rio Pinheiros drainage in Santa Catarina state is diagnosed by a single dark midlateral stripe, absence of associated dark dorsolateral or ventrolateral stripes or blotches in adults, a terminal to slightly oblique mouth, and absence of the first mandibular-canal pore (pore W). A phylogenetic analysis of primarily osteological data supported the new species as sister to a group composed of J. eirmostigma and J. eigenmanni within the subgenus Plesiojenynsia. A key to Jenynsia species is provided

The first report of luminescent liver tissue in fishes: Evolution and structure of bioluminescent organs in the deep-sea naked barracudinas (Aulopiformes: Lestidiidae)

Bioluminescent organs that provide ventral camouflage are common among fishes in the meso-bathypelagic zones of the deep sea. However, the anatomical structures that have been modified to produce light vary substantially among different groups of fishes. Although the anatomical structure and evolutionary derivation of some of these organs have been well studied, the light organs of the naked barracudinas have received little scientific attention. This study describes the anatomy and evolution of bioluminescent organs in the Lestidiidae (naked barracudinas) in the context of a new phylogeny of barracudinas and closely related alepisauroid fishes. Gross and histological examination of bioluminescent organs or homologous structures from preserved museum specimens indicate that the ventral light organ is derived from hepatopancreatic tissue and that the antorbital spot in Lestrolepis is, in fact, a second dermal light organ. In the context of the phylogeny generated from DNA-sequence data from eight gene fragments (7 nuclear and 1 mitochondrial), a complex liver with a narrow ventral strand running along the ventral midline evolves first in the Lestidiidae. The ventral hepatopancreatic tissue later evolves into a ventral bioluminescent organ in the ancestor of Lestidium and Lestrolepis with the lineage leading to the genus Lestrolepis evolving a dermal antorbital bioluminescent organ, likely for light-intensity matching. This is the first described hepatopancreatic bioluminescent organ in fishes. J. Morphol. 276:310-318, 2015