A revision of the genus Pseudoscopelus Lütken (Chiasmodontidae: Acanthomorphata) with descriptions of three new species

Abstract

Pseudoscopelus Lütken is a genus of meso- and bathypelagic fishes with a worldwide distribution. The genus is the most diversified within the family Chiasmodontidae, containing 16 valid species, three of which are described herein as new: Pseudoscopelus scriptus Lütken, from the western Central and North Atlantic; P. sagamianus Tanaka, from the Eastern Pacific and Indian Ocean; P. altipinnis Parr, widely distributed in the Atlantic and Pacific Oceans; P. cephalus Fowler, only known from the type locality in the Indo-Pacific; P. obtusifrons Fowler, from the Atlantic, Indian and Pacific Oceans; P. scutatus Krefft, widely distributed in the Atlantic, Indian and Pacific Oceans; P. aphos Prokofiev and Kukuev, from the western North Atlantic; P. parini Prokofiev and Kukuev, from the western Central Pacific to Hawaiian islands; P. astronesthidens Prokofiev and Kukuev, from the North Atlantic; P. australis Prokofiev and Kukuev, widely distribution in the southern parts of the Atlantic, Indian, Pacific Oceans, and in the Southern Ocean; P. pierbartus Spitz, Quéro and Vayne, from the North Atlantic and western South Atlantic; P. bothrorrhinos Melo, Walker Jr. and Klepadlo, from the western Pacific and Indian Ocean; P. lavenbergi Melo, Walker Jr. and Klepadlo, from the western North, western Central and western South Atlantic, P. paxtoni new species, from the western South Pacific; P. cordilluminatus new species, from the Indian Ocean and eastern South Atlantic; and P. odontoglossum new species, from the Central Pacific. Herein, Pseudoscopelus stellatus is placed in synonymy of P. scriptus; P. albeolus, in synonymy of P. australis; and P. vityazi, in synonymy of P. parini. Pseudoscopelus microps is confirmed as a junior synonym of P. altipinnis. A key to the species of Pseudoscopelus is provided as well as updated diagnoses, redescriptions, areas and distribution maps, based on extensive examination of collection material and comparison with type specimens.

A phylogenomic framework for pelagiarian fishes (Acanthomorpha: Percomorpha) highlights mosaic radiation in the open ocean

“…Pelagiaria includes tunas, which are among the most commercially significant, anatomically well-understood and physiologically remarkable of all fishes [7]. Tunas represent only about 5% of pelagiarian species, and are joined by a diversity of less prominent but no less spectacular lineages, including: swallowers (Chiasmodontidae), which contain bioluminescent species as well as those that engulf prey larger than themselves [8]; butterfishes and kin (Stromateoidei), which possess remarkable pharyngeal feeding structures and often develop commensal relationships with pelagic invertebrates [9]; scabbardfishes (Trichiuridae), with long, eel-like bodies [10]; the butterfly kingfish (Gasterochisma), which evolved endothermy independently of the closely related tunas [11]; and the mysterious ragfish (Icosteus), which possesses a weakly mineralized, largely cartilaginous skeleton, and displays contrasting juvenile and adult forms once assigned to separate species [12].…”

The Scientific Explorations for Deep-Sea Fishes in Brazil: The Known Knowns, the Known Unknowns, and the Unknown Unknowns

“…The many efforts to obtain samples from greater marine depths since the beginning of the twenty-first century are contributing to cover such gaps and boosting significant gains to better understand the biodiversity of deep-sea fishes in the western South Atlantic. In the past years, a number of scientific contributions were published focusing on the deep-sea fish fauna, including general inventories and books (De Figueiredo et al 2002;Madureira et al 2004;Bernardes et al 2005b;Costa et al 2007;Lavrado and Brasil 2010;Oliveira et al 2015), ecological data on distribution and abundance (Bernardes and Rossi-Wongtschowski 2007;Braga et al 2014), comprehensive taxonomic reviews Santos and Figueiredo 2008;Melo 2009Melo , 2010Lima et al 2011), and descriptions of sixteen new taxa (see above).…”

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

“…The patterns of the serial photophores in Pseudoscopelus spp. subsequently have been important in the taxonomy of the group (Melo, ; Melo et al ., ; Prokofiev, ; Spitz et al ., ), but their anatomical structure has not been determined and whether bioluminescence in Pseudoscopelus spp. is intrinsic or bacterial has not been established (Davis et al ., ).…”

“…We grossly examined photophores and the homologous skin in non‐bioluminescent taxa with a Leica MZ 12.5 stereomicroscope (http://www.leica-microsdystems.com). We used the photophore terminology of Prokofiev and Kukuev () as modified by Melo (). We photographed whole specimens using a Canon EOS Rebel T3i camera with macro lens (http://www.canon.com).…”

“…For histological sections, lateral at left: *, probable photogenic cells; ct, collagen‐rich connective tissue; m, acidic‐polysaccharide containing mucous cell; mxf, maxillary photophore series; s, likely protein‐containing serous mucous cell; saf, anal‐fin photophores. Standard photophore abbreviations from Prokofiev and Kukuev () as modified by Melo ()…”