Michael J. Ghedotti

Phylogeny, Classification, and Evolution of Salinity Tolerance of the North American Topminnows and Killifishes, Family Fundulidae (Teleostei: Cyprinodontiformes)

Abstract The North American topminnows and killifishes in the Family Fundulidae (Cyprinodontiformes) are widely distributed in freshwater, brackish, and coastal marine environments of North America, the Yucatan Peninsula, and Bermuda. Fundulid fishes are often found in habitats that undergo substantial variation in environmental conditions. Salinity tolerance of fundulids varies substantially, and some estuarine species can survive in water that is more than three times marine salinity, whereas other freshwater species can only tolerate up to one-third marine salinity. While the Family Fundulidae has been the focus of numerous phylogenetic investigations, their evolutionary relationships to other cyprinodontiforms and the evolutionary history of species within the family are in need of further investigation with robust taxonomic sampling. In this study we provide the most data-inclusive current hypothesis of evolutionary relationships for the Fundulidae, based on a combination of morphological, karyologic...

A New Jenynsia Species (Teleostei, Cyprinodontiformes, Anablepidae) from Southern Brazil and its Phylogenetic Position

Abstract A new species of the genus Jenynsia from southern Brazil is described. The analyses of character states, primarily osteological, support the new species as belonging to the subgenus Plesiojenynsia. A new hypothesis of phylogenetic relationships for the genus, including the new taxon, is presented. The new species, from the Rio Iguaçu drainage in the Brazilian state of Paraná, is diagnosed by the following combination of characters: absence of mandibular canal pore W, long epiotic processes in adults, ten anal-fin rays, discontinuous midlateral and dorsolateral stripes formed by series of blotches on body, midlateral stripe discontinuous anterior to dorsal-fin origin, large third hypobranchial, and presence of teeth on fourth ceratobranchial of adults. Uma nova espécie do gênero Jenynsia do sul do Brasil é descrita. As análises de estados de caracteres, principalmente osteológicos, suportam a nova espécie como pertencente ao subgênero Plesiojenynsia. Apresenta-se uma nova hipótese de relações filogenéticas para o gênero, incluindo o novo táxon. A nova espécie, da bacia do Rio Iguaçu no Estado do Paraná, é diagnosticada pela seguinte combinação de caracteres: ausência do poro W do canal mandibular; processos epióticos longos nos adultos, dez raios na nadadeira anal; faixas dorso-lateral e mediano-lateral descontínuas e formadas por uma série de máculas nos flancos; faixa mediano-lateral descontínua anterior a origem da nadadeira dorsal; terceiro hipobranquial grande; e presença de dentes no quarto ceratobranquial dos adultos.

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.

New Species of Jenynsia (Teleostei: Cyprinodontiformes) from Southern Brazil and Its Phylogenetic Relationships

Abstract 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.

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

Abstract 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 rathbuni 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.

Descriptions of Two New Species of Jenynsia (Cyprinodontiformes: Anablepidae) from Southern Brazil

Two new species in the genus Jenynsia from southern Brazil are described. Jenynsia eirmostigma sp. nov. from the rio Pelotas drainage in Santa Catarina and Rio Grande do Sul states is diagnosed by the presence of three distinct, discontinuous lateral stripes and a slightly oblique mouth.Jenynsia unitaenia sp. nov. from coastal drainages in the states of Santa Catarina and Rio Grande do Sul is diagnosed by the presence of a single distinct, continuous lateral stripe, more than 13 gill rakers on the ventral arm of the first gill arch, and a slightly subterminal mouth. The species in the genus Jenynsia that is most similar to the two new species is J. eigenmanni (Haseman). A key to the described species of Jenynsia is provided. Duas novas especies do generoJenynsia do sul do Brasil slo descritas.Jenynsia eirmostigma sp. nov. das drenagens do rio Pelotas, estados de Santa Catarina e Rio Grande do Sul, e diagnosticada pela presenia de tres listras laterais distintas e descontinuas e boca ligeiramente obliqua.Jenynsia unitaenia sp. nov. das drenagens costeiras, estados de Santa Catarina e Rio Grande do Sul, e diagnosticada por uma unica listra lateral distinta e continua, mais que 13 raios na nadadeira dorsal, e boca ligeiramente subterminal. A especie do genero Jenynsia mais semelhante s duas novas especies e J. eigenmanni (Haseman). Se apresenta uma chave para as especies descritas do genero Jenynsia.

The taxonomic placement of three fossil Fundulus species and the timing of divergence within the North American topminnows (Teleostei: Fundulidae)

The fossils species †Fundulus detillae, †F. lariversi, and †F. nevadensis from localities in the western United States are represented by well-preserved material with date estimations. We combined morphological data for these fossil taxa with morphological and DNA-sequence data to conduct a phylogenetic analysis and a tip-based divergence-time estimation for the family Fundulidae. The resultant phylogeny is largely concordant with the prior total-evidence phylogeny. The fossil species do not form a monophyletic group, and do not represent a discrete western radiation of Fundulus as previously proposed. The genus Fundulus diverged into subgeneric clades likely in the Eocene or Oligocene (mean age 34.6 mya, 53-23 mya), and all subgeneric and most species-group clades had evolved by the middle Miocene. †Fundulus lariversi is a member of subgenus Fundulus in which all extant species are found only in eastern North America, demonstrating that fundulids had a complicated biogeographic history. We confirmed †Fundulus detillae as a member of the subgenus Plancterus. †F. nevadensis is not classified in a subgenus but likely is related to the subgenera Plancterus and Wileyichthys.

Morphology and evolution of bioluminescent organs in the glowbellies (Percomorpha: Acropomatidae) with comments on the taxonomy and phylogeny of Acropomatiformes

Bioluminescent organs have evolved many times within teleost fishes and exhibit a wide range of complexity and anatomical derivation. Although some bioluminescent organs have been studied in detail, the morphology of the bacterial light organs in glowbellies (Acropoma) is largely unknown. This study describes the anatomy of the bioluminescent organs in Hanedas Glowbelly (Acropoma hanedai) and the Glowbelly (Acropoma japonicum) and places the evolution of this light‐producing system in the context of a new phylogeny of glowbellies and their relatives. Gross and histological examination of the bioluminescent organs indicate that they are derived from perianal ectodermal tissue, likely originating from the developmental proctodeum, contrary to at least one prior suggestion that the bioluminescent organ in Acropoma is of endodermal intestinal derivation. Additionally, anterior bioluminescent organ development in both species is associated with lateral spreading of the bacteria‐containing arms of the bioluminescent organ from an initial median structure. In the context of a 16‐gene molecular phylogeny, the bioluminescent organ in Acropoma is shown to have evolved within the Acropomatidae in the ancestor of Acropoma. Further, ancestral‐states reconstruction demonstrates that the bioluminescent organs in Acropoma evolved independently from the light organs in related howellid and epigonid taxa which have esophageal or intestinally derived bioluminescent organs. Across the acropomatiforms, our reconstructions indicate that bioluminescent organs evolved independently four or five times. Based on the inferred phylogeny of the order where Acropoma and Doederleinia were separated from other traditional acropomatids, the familial taxonomy of the Acropomatidae was modified such that the previously described Malakichthyidae and Synagropidae were recognized. We also morphologically diagnose and describe the family Lateolabracidae.