248 



Fishery Bulletin 102(2) 



Pectoral fin notched, of 16 (15) rays. Upper lobe of 8 (8) 

 rays, the 2 (2) notch rays more widely spaced and placed 

 exactly at middle of fin base. In holotype, left lower pec- 

 toral lobe with 6, on right 5, rays. In paratype, 5 rays on 

 each side. Bases of lower-lobe rays stronger and thicker 

 than those of upper-lobe rays. Level of uppermost pectoral 

 ray below horizontal through lower end of upper jaw. Base 

 of pectoral fin close to vertical, lowest ray almost directly 

 below uppermost. Upper-lobe rays not reaching anal fin 

 origin, lower-lobe rays not reaching vertical through ends 

 of upper lobe rays. In holotype, length of notch rays 1.7 

 times in upper pectoral-fin lobe length, lower pectoral-fin 

 lobe 1.4 times in it. 



Body not humpbacked, dorsal contour of back almost 

 straight; spine horizontal, its anterior end not dorsally 



"'Vt 



B 



Figure 2 



Details of anatomy of Psednos rossi. (A) Cephalic pores 

 and prominent features of head. Portions of sensory canals 

 passing through bones are stippled. N = nostril and olfac- 

 tory rosette; io = infraorbital pores, n = nasal pores, t = 

 temporal pores; S = symphyseal knob; R = retroarticular 

 process. (B) Teeth of paratype: (leftl frontal view; (right) 

 lateral view. Tooth length about 0.25 mm. (C) First gill 

 arch of paratype, USNM 372727. right side; view from 

 inside of gill cavity. Raker height about 0.3 mm. 



curved (Fig. 3). Neural spines of vertebrae 1-4 neither 

 longer nor broader than those posterior, unlike other spe- 

 cies (see Fig. 5 in Chernova, 2001). Maximum body depth 

 4.2 (4.0) times in standard length and 1.6(1.5) times depth 

 at anal-fin origin. In holotype, occiput slightly swollen 

 (Fig. 3); in paratype, dorsal outline of head and back in 

 front of dorsal fin origin almost perfectly flat (Fig. 1), pos- 

 sibly an age-related difference. Abdominal part of body 

 long, preanal length almost half of standard length. Inter- 

 neural of first dorsal-fin ray between neural spines 3 and 

 4. Dorsal and anal fins moderately deep, maximum depth 

 of erect dorsal fin in paratype 8.9 times in SL, 2.7 times in 

 head length (damaged in holotype). Dorsal and anal fins 

 overlapping about one-third of caudal-fin length. Anus on 

 vertical behind head, slightly behind base of uppermost 

 pectoral ray. Skin transparent. Gelatinous subcutaneous 

 tissue weakly developed. In holotype (smaller specimen) 

 body not as deep and jaws longer than in the paratype 

 (larger specimen). Differences in head width and interor- 

 bital width are great because head of paratype was slightly 

 compressed during fixation. Other proportions similar to 

 those of holotype. 



Body color in alcohol pale; under magnification, slightly 

 dusky blotches of dots present caudally in paratype and 

 absent in holotype. Head musculature pale. Black perito- 

 neum visible through body wall. Mouth and gill cavities, 

 gill arches, tongue, and both jaws black; gill rakers pale. 

 Musculature of pectoral girdle appears pale on lateral 

 surface of belly. Color in life orange-rose. 



Distribution 



Western North Atlantic off Cape Hatteras, mesopelagic 

 at depths of 500-674 m. 



Etymology 



The patronym "rossi" after Steve W. Ross, who initially 

 notified us of the captures and furnished the specimens 

 to us for examination. 



Comparative notes 



Psednos rossi seems to belong to the P. christinae group 

 (see Chernova, 2001; Chernova and Stein, 2002), includ- 

 ing P. andriashevi, P. barnardi, P. christinae. P. dentatus, 

 P. groenlandicus, and P. harteli. Species of this group are 

 characterized by vertebrae 46-47, dorsal-fin rays 38-42, 

 anal-fin rays 33-35, and coronal pore absent (versus the 

 P. micrurus group having vertebrae 40-44. dorsal-fin rays 

 34-38, anal-fin rays 28-33, and coronal pore present) 

 (Chernova, 2001). Psednos rossi distinctly differs from the 

 other species of the christinae group in at least having 

 occiput not swollen (vs. greatly swollen), not humpbacked 

 because the vertebral column is straight (vs. humpbacked 

 owing to the greatly curved anterior part of the spine), 

 mouth vertical with jaws at 90° to horizontal, symphysis 

 of upper jaw above level of eye (vs. a more or less oblique 

 mouth at an angle of 30-45° and the upper jaw. symphysis 

 on a horizontal with the lower half of the eve); and anus 



