Morphology and evolution of the luminous roughy bioluminescent organ (Teleostei: Trachichthyidae)

INTRODUCTION Bioluminescent organs in fishes that produce ventral camouflage against a background of downwelling light are very common, yet their anatomy often is poorly understood (Hastings, 1971; Young & Roper, 1976). Camouflage via ventral bioluminescence has evolved at least seven times within a wide range of teleosts (Haddock et al., 2010; Davis et al., 2014, 2016) and they vary greatly in the anatomical structures that form them (Haygood et al., 1994; Chakrabarty et al., 2011; Ghedotti et al., 2015, 2018). The luminous roughies (genus Aulotrachichthys) have a light organ in the region of the anus that houses lumiescent bacteria in the genus Photobacterium. Kuwabara (1955) and Haneda (1957) discuss the anatomy and function of the bioluminescent organ in A. prosthemius noting that it contained Photobacterium in lobules in an area around the anus (Fig. 1) and a light conducting structure they called the “unknown” structure or the filiform body respectively. We seek to determine more specifically the structure of the bioluminescent organ in A. prosthemius and determine if Paratrachichthys, a closely related genus, is similarly bioluminescent. We also generate a phylogeny to better understand the evolution of bioluminescence in the Family Trachichthyidae

Phylogenetic analysis and taxonomy of the poecilioid fishes (Teleostei: Cyprinodontiformes)

Evidence from morphology is used to infer the phylogeny of the superfamily Poecilioidea using other cyprinodontoid fishes as outgroups. The three equally most parsimonious trees resulting from the phylogenetic analysis support the monophyly of the families Anablepidae and Poeciliidae with respect to each other, but the previous taxonomy within the Poeciliinae is not consistent with the resultant phylogenetic trees. The Poeciliidae is recognized with three subfamilies: the Aplocheilichthyinae containing solely Aplocheilichthys spilauchen, the Procatopodinae containing Fluviplylax (Fluviphylacini) and the African lamp-eyed killifishes (Procatopodini), and the Poeciliinae. The inferred hierarchical relationships of included suprageneric taxa are: ((Oxyzygonectinae, Anablepinae) (Aplocheilichthyinae ((Fluviphylacini, Procatopodini) (Alfarini (Priapellini (Gambusini (Heterandrini (Cnesterodontini (Girardini, Poeciliini))))))))). The tribe Alfarini is resurrected and a new tribe, the Priapellini, is described. Tomeurus gracilis is not the most basal poeciliine, and facultative viviparity in Tomeurus is not a plesiomorphic intermediate condition of viviparity retained from the common ancestor of poeciliines. Facultative viviparity in Tomeurus is the result of an evolutionary loss of obligate viviparity. Tomeurus gracilis is recognized as a member of the tribe Cnesterodontini. Lamprichthys tanganicus and Micropanchax pelagicus are not sister taxa, and the pelagic lacustrine habits of these two species are inferred to have evolved independently. Based on the principles of vicariance biogeography, the origin of the Poecilioidea is inferred to have occurred before the separation of Africa and South America. © 2000 The Linnean Society of London

A new species of Jenynsia (Cyprindontiformes: Anablepidae) from Brazil with comments on the composition and taxonomy of the genus

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Phylogeny, classification, and evolution of salinity tolerance of the North American topminnows and killifishes, family Fundulidae (Teleostei: Cyprinodontiformes) /

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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 Wileyich-Thys

A new Jenynsia species (Teleostei, Cyprinodontiformes, Anablepidae) from southern Brazil and its phylogenetic position

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. © 2006 by the American Society of Ichthyologists and Herpetologists

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

Using independent research projects to foster learning in the comparative vertebrate anatomy laboratory

This paper presents a teaching methodology involving an independent research project component for use in undergraduate Comparative Vertebrate Anatomy laboratory courses. The proposed project introduces cooperative, active learning in a research context in a Comparative Vertebrate Anatomy course. This project involves pairs or groups of three students testing a hypothesis concerning variation of an anatomical feature among vertebrates and an oral or poster presentation that reports the results. The project requires both examination of anatomical descriptions in scientific literature and direct anatomical investigation of vertebrate specimens available in the laboratory. This project component has been used successfully at two schools, where it increased student enthusiasm for the discipline, increased student interpretive skills, and better placed the course material within the context of science. Both faculty and student perceptions of the successes and difficulties of such a project are presented

The first evidence of intrinsic epidermal bioluminescence within ray-finned fishes in the linebelly swallower Pseudoscopelus sagamianus (Chiasmodontidae)

External and histological examination of the photophores of the linebelly swallower Pseudoscopelus sagamianus reveal three epidermal layers of cells that form the light-producing and light-transmitting components of the photophores. Photophores among the examined photophore tracts are not significantly different in structure but the presence of mucous cells in the superficial layers of the photophore suggest continued function of the epidermal photophore in contributing to the mucous coat. This is the first evidence of intrinsic bioluminescence in primarily epidermal photophores reported in ray-finned fishes

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