Pseudoscopelus aphos Prokofiev & Kukuev 2006, 2005

Melo, Marcelo R. S., 2019, A revision of the genus Pseudoscopelus Lütken (Chiasmodontidae: Acanthomorphata) with descriptions of three new species 2710, Zootaxa 2710 (1), pp. 1-78 : 49-50

Pseudoscopelus aphos Prokofiev & Kukuev 2006

Figures 22 A–B , 23 A , 28 O; Table 8.

Pseudoscopelus aphos Prokofiev and Kukuev 2006a: 572–727 [type locality: western North Atlantic , 34º N, 50º W, holotype ZMMU 16468 , 145.0 mm]; 2008: 46–50, figures 12, 34, 67, 99–101 [species account].

Pseudoscopelus stellatus Beebe 1932: 76–79 [in part, three specimens used in description; western North Atlantic ].

Diagnosis. A species of the Pseudoscopelus aphos species group, which can be distinguished from P. parini by the complete absence photophores or clear lines on body (vs. clear lines in place of photophores in ventral part of body in Pseudoscopelus parini , and photophores present in all other species).

Description. Medium-sized species of Pseudoscopelus , largest specimen examined 60.7 mm SL. Morphometric data summarized in Table 8. General body shape as described for genus with diagnostic characteristics of species and species group.

First dorsal-fin rays vii (1), viii (2), ix (2); second dorsal-fin rays xxiii (1), xxiv (1), xxvii (1), ii+21 (2); anal-fin rays iii+20 (2), iii+21 (2), iii+23 (1); pectoral-fin rays 12 (1), 14 (1), 15 (1); pelvic-fin rays I+5 (5); caudal-fin rays i+7+8+i (4), i+8+7+i (1). Branchiostegal rays 7 (5). Pre-caudal vertebrae 18 (2); total vertebrae 36 (2).

Lateral line complete; lateral-line pores 74 (1), 75 (1), 76 (1), 77 (2). Pores in temporal canal 2 (5); supratemporal canal 3 (5); otic canal 2 (5); supraorbital canal 5 (5); supranasal pore 4 (5); epiphyseal branch 3 (5); infraorbital canal 12 (5); preopercular canal 5 (3), 6 (2); mandibular canal 6 (5); fifth pore of mandibular canal 1 (3).

Dentition. Enlarged teeth on premaxilla, dentary and palatine. Teeth arrangement as illustrated for Pseudoscopelus scriptus . Premaxilla moderately wide, widest point of premaxillary body 10–14 % in premaxillary length.

Premaxillary teeth on head, neck, body and caudal process. Lateral series in single longitudinal row, along lateral edge of premaxillary head, neck, body and caudal process; teeth conical, slightly curved. Canine and fang on ventral shelf of premaxillary head. Middle and mesial series of premaxilla on ventral shelf of body. Middle series in two, irregular, longitudinal rows; teeth needle-like, straight, gradually increasing in size from lateral to medial. Mesial series in transverse rows, each row with three to four teeth; teeth needle-like, slightly curved, gradually increasing in size from medial to mesial.

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 in transverse rows of one to four teeth; teeth straight, needle-like, gradually increasing in size from lateral to mesial. Palatine teeth 3 (4), 5 (1).

Teeth on infrapharyngobranchials and fifth ceratobranchial, conical, curved. Teeth on second basibranchial 9 (1), 10 (2), 11 (1), 12 (1), conical, in V -shaped or two rows. Teeth absent on basihyal and other basibranchials. Gill rakers on first epibranchial 0 (5); first ceratobranchial 8 (2), 9 (1), 11 (1), 14 (1); first hypobranchial 4 (1), 5 (1), 6 (2), 9 (1). Gill rakers absent on other elements.

Color. Specimens preserved for long time faded to light brown. Body uniformly dark brown, including skin on epiphyseal branch. Pectoral, pelvic, first and second dorsal, and anal fins slightly pigmented at their bases; caudal fin black or dark brown. Internal area of mouth and gill arches pale.

Luminescent organs. Photophores completely absent.

Distribution. In the western North Atlantic; from 24º N to 40º N, 50º W to 76º W ( Fig. 23 A ).

Bathymetric distribution. Meso- to bathypelagic, from 220 to 1634 m (mean 667).

Remarks. Prokofiev and Kukuev (2005) presented an erroneous description of color. They based the description on a poorly preserved specimen, which was collected in 1977 and kept in formalin since then; the bones were uncalcified and the overall color was faded to brown, typical of museum specimens. They described the color of internal area of mouth as black; in fact there are some melanophores on the skin of premaxilla and dentary, especially on dentigerous areas and on basibranchials, which gives a dusky aspect.

The data presented herein is based on a reasonable amount of specimens from the type locality and adjacent areas. Some specimens are in great shape and have well-preserved pigmentation allowing this to be a more accurate description. The internal areas of mouth and gill arches are demonstrated in Figure 19 B ; it is not as back as described. Based on such mistake, Prokofiev and Kukuev (2008) diagnosed P. aphos from P. parini [see species comments for discussion on species’ status and synonyms], and suggested that it might be related to the P. altipinnis and P. astronesthidens .

Figures

FIGURE 19. Pseudoscopelus paxtoni: (A) NMNZ P. 28657, 205.1 mm, holotype; (B) MNMZ P. 37858, 200.4 mm, paratype.

FIGURE 22. Pseudoscopelus aphos: (A) USNM 296957, 71.9 mm; (B) USNM 296948, 58.6 mm, detail of internal pigmentation of mouth. Pseudoscopelus parini: (C and D) NMNZ P. 24463, 100.8 mm, in lateral and ventral views.

FIGURE 23. Map of distribution of (A) Pseudoscopelus aphos (diamond), P. lavenbergi (cross), and P. parini (circle); (B) P. astronesthidens (cross), P. australis (asterisk), and P. odontoglossum (star). Each symbol may represent more than one locality; solid symbols represent type localities.