Pseudoscopelus bothrorrhinos Melo, Walker Jr. & Klepadlo 2007

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 : 47-49

Pseudoscopelus bothrorrhinos Melo, Walker Jr. & Klepadlo 2007

Figures 18 B , 20 C–D , 21 B , 28 J; Table 7.

Pseudoscopelus bothrorrhinos Melo et al. 2007: 41–44 , figures 7, 8, and 9 [type locality: western Central Pacific , 2°51’S, 169°55’ E, holotype LACM 31502-2 , 45.9 mm].

Pseudoscopelus legandi Lavenberg 1974:197–210 , figures 42–44 [Indian and Pacific Oceans; name not available in accordance to the ICZN 1999].

Pseudoscopelus scutatus (non Krefft) Prokofiev and Kukuev 2008: 127–136, figures 184–186 [in part].

Diagnosis. A species of the Pseudoscopelus scutatus species group, which can be distinguished from its congeners by a unique characteristic of photophore pattern: lpf present (vs. lpf absent).

Description. Small-sized species of Pseudoscopelus , largest specimen 55.1 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 vii (11*); second dorsal-fin rays ii+20 (1), ii+21 (8*), ii+22 (2); anal-fin rays ii+20 (1), ii+22 (1), iii+20 (3), iii+21 (6*); pectoral-fin rays 12 (1), 13 (2), 14 (8*); pelvic-fin rays I+5 (11*); caudalfin rays i+7+7+i (1*), i+7+8+i (10). Branchiostegal rays 7 (11*). Pre-caudal vertebrae 17 (1), 18 (9); total vertebrae 35 (1), 36 (13*).

Lateral line complete; lateral-line pores 73 (1), 74 (2), 75 (2), 76 (5*), 77 (1). Pores in temporal canal 2 (11*); supratemporal canal 3 (11*); otic canal 2 (11*); supraorbital canal 6 (11*); supranasal pore 3 (11*); epiphyseal branch 2 (1), 3 (10*); infraorbital canal 12 (10*), 13 (1); preopercular canal 5 (11*); mandibular canal 6 (11*); fifth pore of mandibular canal 1 (11*).

Dentition. Enlarged teeth on premaxilla, dentary and palatine. Teeth arrangement illustrated in Melo et al. (2007). 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 rows; 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 two, longitudinal rows; teeth straight, needle-like. Palatine teeth 4 (1), 5 (5*), 6 (2), 7 (2), 8 (1); in single, longitudinal row.

Teeth on infrapharyngobranchials and fifth ceratobranchial, conical, curved. Teeth on second basibranchial 5 (1), 6 (3), 7 (2), 8 (2*), 9 (1), 10 (1), 11 (1), conical, in V-shaped or single, irregular row. Teeth absent on basihyal and other basibranchials. Gill rakers on first epibranchial 0 (11*); first ceratobranchial 6 (2*), 7 (5*), 8 (2), 9 (2); first hypobranchial 1 (1), 2 (9*), 4 (1). Gill rakers absent on other elements.

Luminescent organs. Luminescent organs present as discrete photophores on head and body ( Fig. 21 B ). Photophores on head: apf, dnf, inof 1–2, lpf, mxf, vnf, opf, pof and ppf absent; lpf at anterior edge of preopercle, extending dorsally to middle of preopercle; amf in two to three rows, medial to mandibular canal, between second and third pores; pmf in single row, 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, scf, and spf absent; if in two rows, from isthmus to ventral edge of cleithrum; prvf in single row, from posterior to cleithrum, connected to ptvf, posteriorly and extending to slightly anterior to anus; svf triangular, anterodorsal to pelvic-fin; free photophores between svf and pectoral fin present or absent; saf in single row, oval, not extending anteriorly to anus, and disconnected posteriorly; prcf two-pronged, prongs extending laterally on lower procurrent rays.

Color. No freshly collected specimen known, most specimens 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. In the Equatorial western Central Pacific, off the Gilbert Islands, Papua New Guinea, and Indonesia; from 1° to 4° S, 169° to 129° E. A single record in the western Indian, off the Comoros Islands; from 12° S, 44° E ( Fig. 18 B ).

Bathymetric distribution. Meso- to bathypelagic, from 146 to 1200 m (mean 719 m).

Remarks. Prokofiev and Kukuev (2008) fail to include this species in their revision but listed and illustrated the lot IORAN uncatalogued (1, 27.0, figures 184–186) under P. scutatus , even though the photophores clearly stand for P. bothrorrhinos .

Figures

FIGURE 18. Maps of distribution of (A) Pseudoscopelus altipinnis (triangle) and P.paxtoni (star); (B) P. scutatus (star) and P. bothrorrhinos (diamond). Each symbol may represent more than one locality; solid symbols represent type localities.

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.

FIGURE 21. Schematic drawing of the photophore pattern in lateral and ventral vies of (A) Pseudoscopelus scutatus, ISH 567b-c/1966, 80.4 mm, paratype; (B) P. bothrorrhinos, SIO 07-6, 39.6 mm, paratype.