A revision of the genus Pseudoscopelus Lütken (Chiasmodontidae: Acanthomorphata) with descriptions of three new species 2710 Author Melo, Marcelo R. S. text Zootaxa 2019 2010-12-03 2710 1 1 78 http://dx.doi.org/10.11646/zootaxa.2710.1.1 journal article 10.11646/zootaxa.2710.1.1 1175­5334 6031390 Pseudoscopelus scutatus Krefft 1971 Figures 16 C , 18 B , 20 A–B , 21 A , 28 I ; Table 7 . Pseudoscopelus scutatus Krefft 1971: 165–174 , Figs. 1–8 [type locality: eastern North Atlantic, 2°44’ N , 25°12’ W , holotype ISH 567a/66, 84.7 mm ]; Lavenberg 1974: 183–196 , figures 41–42 [Atlantic and Pacific Oceans]; Nakabo et al. 1992 [western North Pacific]; Nakabo 2002 [key to species]; Moore et al. 2003: 227 [western North Atlantic]; Figueiredo et al. 2003: 94 [literature compilation]; Prokofiev and Kukuev 2006a: 228–229 , figure 5 [western North Atlantic, eastern Central Atlantic]; 2006c [key to species]; 2008: 125–136, figures 20, 50, 54–56, 69, 180–183 [in part, species account]. Diagnosis. A species of the Pseudoscopelus scutatus species group, which can be distinguished from P. bothrorrhinos by a single characteristic: lpf absent ( vs. lpf present). FIGURE 20. Pseudoscopelus scutatus : (A) USNM 236776, 70.0 mm; (B) lateral view of head of ISH 567b-c/1966, 80.4 mm, paratype. Pseudoscopelus bothrorrhinos : (C) LACM 31502-2, 45.9 mm, holotype; (D) LACM 56616-1, 38.1 mm, paratype, dorsal view of a cleared stained specimen, arrows indicate the plate-like distal radials of first dorsal fin. Scale bar equals 5.0 mm. Description. Medium-sized species of Pseudoscopelus , largest specimen examined 91.0 mm SL. Morphometric data summarized in Table 7 . General body shape as described for genus with diagnostic characteristics of species and species group. First dorsal-fin rays vi (3), vii (8), viii (1); second dorsal-fin rays ii+20 (3), ii+21 (6), ii+22 (3); anal-fin rays ii+22 (1), iii+20 (4), iii+21 (5), iii+22 (2); pectoral-fin rays 13 (3), 14 (8), 15 (1); pelvic-fin rays I+5 (12); caudal-fin rays i+7+8+i (12). Branchiostegal rays 7 (12). Pre-caudal vertebrae 17 (5), 18 (9); total vertebrae 35 (2), 36 (10), 37 (2). Lateral line complete; lateral-line pores 74 (1), 75 (2), 76 (2), 77 (2), 78 (2), 79 (1), 80 (1). Pores in temporal canal 2 (12); supratemporal canal 3 (12); otic canal 2 (12); supraorbital canal 6 (12); supranasal pore 3 (12); epiphyseal branch 3 (12); infraorbital canal 12 (12); preopercular canal 5 (12); mandibular canal 6 (12); fifth pore of mandibular canal 1 (12). Dentition. Enlarged teeth on premaxilla, dentary and palatine. Premaxilla and dentary illustrated in Figure 16 C . Premaxilla narrow, widest point of premaxillary body 12–14 % in premaxillary length. Premaxillary teeth on head, neck, body and caudal process. Lateral series of teeth in single longitudinal row, along lateral edge of premaxillary head, neck, body and caudal process; teeth slightly curved. Canine and fang on ventral shelf of premaxillary head. Middle and mesial series on ventral shelf of premaxillary body. Middle series in two, irregular, longitudinal row; teeth needle-like, straight, gradually increasing in size from lateral to medial. Mesial series in single, longitudinal row; teeth needle-like, slightly curved. Dentary teeth in lateral and mesial series. Lateral series along lateral shelf of dentary, in single, longitudinal row, extending from symphysis to posterior tip; teeth conical, slightly curved. Mesial series on dorsal shelf of dentary, in single row; teeth straight, needle-like. Palatine teeth 3 (4), 4 (5), 5 (3); in single, longitudinal row. Teeth on infrapharyngobranchials and fifth ceratobranchial, conical, curved. Teeth on second basibranchial 6 (2), 7 (2), 8 (2), 9 (3), 11 (1), 12 (1), conical, in V-shaped or single, irregular row. Teeth absent on basihyal and other basibranchials. Gill rakers on first epibranchial 0 (12); first ceratobranchial 5 (2), 6 (4), 7 (4), 8 (2); first hypobranchial 1 (4), 2 (5), 3 (3). Gill rakers absent on other elements. Luminescent organs. Luminescent organs present as discrete photophores on head and body ( Fig. 21 A ). Photophores on head: dnf , inof 1–2, lpf , mxf , opf , pof and ppf absent; apf in angle between dentary and preopercle; vnf absent from most specimens, and if present as small patch posterior to anteriormost pore of supraorbital canal; amf in two to three rows, medial to mandibular canal, between second and third pores; pmf in one to two rows, anteriorly medial to mandibular canal, posteriorly lateral to mandibular canal, from forth pore to halfway between fifth and sixth pores. Photophores on body: lvf , pf, paf , vaf , vf , trf , rtf , and spf absent; scf usually absent, present as three photophores in a single specimen (USNM 240671); if in two rows, from isthmus to ventral edge of cleithrum; prvf in irregular single row, from posterior to cleithrum, connected to ptvf posteriorly and extending to slightly anterior to anus; svf triangular, anterodorsal to pelvic-fin; saf in two rows, oval, not extending anteriorly to anus, and connected posteriorly; prcf oval-shaped or three-pronged, medial prong extending over anteriormost lower procurrent rays. Identification of juveniles. The smallest specimen recognized has 28.4 mm (SIO 68-537); the identification was concave shape of snout and the complete development of photophore groups. Color. Specimens preserved for long time faded to light brown. Body brown or dark brown, except for triangular area on epiphyseal branch. Pectoral, pelvic first and second dorsal, anal and caudal fins hyaline. Internal area of mouth and gill arches pale. Distribution. Widely distributed in the Atlantic Ocean, from 40° N to 30° S , 22° to 83° W . A single record in the Indian Ocean, from the Arabian Sea; from 2°00’ N , 55°00’ W . In the Pacific Plate; from 22° N to 25° S , 100° W to 157° W ( Fig. 18 B ). Bathymetric distribution. Meso- to bathypelagic, from 85 to 1716 m (mean 578 m ).