Owstonia psilos, Smith-Vaniz, William F. & Johnson, David, 2016

Smith-Vaniz, William F. & Johnson, David, 2016, Hidden diversity in deep-water bandfishes: review of Owstonia with descriptions of twenty-one new species (Teleostei: Cepolidae: Owstoniinae), Zootaxa 4187 (1), pp. 1-103 : 74-76

Owstonia psilos new species

( Figures 64−66 )

Holotype. NMV A.29673‒004, 82 mm SL, Western Australia, 17°21'30"S, 118°57'19"E – 17°20'53"S, 118°56'48"E, trawled in 437–446 m, R/ V Southern Surveyor , Imperieuse L 23 transect, 15 Jun. 2007.

Paratypes. 9 specimens, 47‒180 mm SL, all from off Western Australia: NMV A.29664‒004 (1, 64), 18°46'27"S, 116°54'45"E –18°46'32S, 116°55'28"E, 400–404 m, R/ V Southern Surveyor , Karratha L 21 transect, 13 Jun. 2007 ; CSIRO H 7136‒24 (1, 132, S. of Scott Reefs, 14°16'S, 122°16'E, 358 m, 6 Jun. 2004; NMV A.29664– 0 15 (1, 47), 17°21'30"S, 118°57'19"E –18°57'19S, 17°20'53"E, 437‒446 m, R/ V Southern Surveyor , Karratha L 23 transect, 15 Jun. 2007 ; NMV A. 29733‒007 (1, 125) 12°36'07"S, 123°25'23"E– 12°36'57"S, 123°26'12"E, 403‒419 m, R/ V Southern Surveyor , Ashmore L30 transect, 8 Jun. 2007 ; NTM S.12608–002 (1, 75), SW of Rowley Shoals, 17°51'S, 118°29'E, 415 m, 7 Nov. 1985; NTM S.12611‒001 (1, 82), SW of Rowley Shoals, 17°28'S, 118°53'E, 405 m, 8 Nov. 1985; NTM S.12727‒004 (2, 150‒180), SW of Rowley Shoals, 17°52'S, 118°28'E, 410 m, Feb. 1990; NTM S.12728‒018 (1, 149), SW of Rowley Shoals, 18°01'S, 118°23'E, 420 m, Feb. 1990.

Diagnosis. A species of Owstonia with LL pattern type 1; dorsal fin III, 21; anal fin I, 14; LL ends below dorsal-fin soft rays 14‒20; oblique body scale rows in mid-lateral series about 32; total gill rakers 36‒40; premaxillary stripe absent, with a few scattered melanophores or with an incomplete brown stripe; dorsal fin anteriorly with interradial membranes of spine 3 to soft rays 4‒5 black at least distally.

Description. (Where counts vary, those of the paratypes are given in parentheses.). A species of Owstonia with LL pattern type 1, consisting of a simple lateral line that originates from the posttemporal sensory canal near the anterodorsal margin of gill opening, curves upward and backward then continues posteriorly just below dorsal-fin base to at least soft ray 14‒20. Dorsal fin III, 21; anal fin I, 14; pectoral fin 22 (20‒23); gill rakers 14 + 25 = 39 (12‒14 + 24‒27 = 36–40). Vertebrae: precaudal 11, caudal 17, total 28; anal-fin pterygiophores anterior to 1st haemal spine 2. Oblique body scale rows in mid-lateral series about 32 (in most specimens too many of these scales are missing to accurately count them); nape scaly and cheek scale rows about 5‒6. Lower limb margin of preopercle without spines. Papillae in slight depression behind tip of premaxillary ascending processes 4, arranged in 2 almost equally spaced pairs. Teeth in outer row of each premaxilla 15-17 (15-24), 21/ 24 in largest specimen, with some anterior teeth moderately elongate with blunt tips; 0‒1 inner teeth anteriorly. Teeth in lateral row of each dentary 8 (7‒12 and 11/ 12 in largest specimen); symphyseal teeth 5 (3‒5), spike-like ( Fig. 9 C), and with 1‒2 inner teeth anteriorly. Pelvic fin short, depressed fin not extending behind anus (not reaching anus in three largest specimens, 125‒180 mm SL). Caudal fin lanceolate. In 9 specimens, 64‒180 mm SL, caudal fin 2.5‒2.8 times in SL; head 2.7‒3.2 times in SL; body depth at anal-fin origin 3.8‒4.5 times in SL.

Color pattern in alcohol: Dorsal fin with interradial membranes of spine 3 to soft rays 4‒5 with dark pigment at least distally; membrane connecting maxilla and premaxilla usually uniformly pale, occasionally (including holotype) with a few scattered melanophores or with an incomplete brown stripe, and inner membrane covering posterior part of dentary pale. A freshly collected 64 mm SL specimen ( Fig. 64 ) has dorsal fin with prominent black blotch anteriorly extending to base of fin; remainder of dorsal, anal, caudal and pectoral fins reddish proximally with white distal margins; pelvic fin mostly white; maxilla, cheek, belly, shoulder girdle and chest ivory; opercle, throat and dorsum of head dark red; iris golden-orange; body posterior to anal-fin origin mostly pale probably due to missing scales.

Proportions of 82 mm SL holotype are given first, followed by those of 8, 64‒ 180 mm SL, paratypes (in parentheses), as percentages of SL: predorsal length 33.3 (29.3‒36.2); preanal length 61.2 (56.9‒66.1); dorsal-fin base 57.4 (52.9–68.1); anal-fin base 26.7 (27.5‒31.2); pelvic-fin length 23.3 (17.1‒24.5); caudal-fin length 39.4 (35.0–39.0); body depth at anal-fin origin 24.7 (22.4‒26.0); head length 35.5 (31.0‒35.8); upper jaw length 20.7 (18.2‒20.8); upper jaw depth 9.3 (8.4–9.6); orbit diameter 16.2 (12.3‒16.8). As percentages of head length: upper jaw length 58.3 (53.7‒61.4); orbit diameter 45.5 (37.6‒48.1).

Comparisons. Species of Owstonia with many of the diagnostic characters of O. psilos all have more oblique body scale rows in mid-lateral series 45–56 (vs. about 32), and further differ (characters of O. psilos in parentheses) as follows: O. crassa has anal fin I, 12–13 (vs. I, 14); O. melanoptera and O. merensis both have dorsal-fin interradial membranes of spine 2 to soft ray 5 black (vs. membranes of spine 3 to soft rays 4‒5 black); O. melanoptera also differs in having the lateral-line terminus below dorsal-fin soft rays 7–8 (vs. 14–20) and O. merensis has anal fin II, 11 (vs. I, 14); O. similis has premaxillary stripe continuous and black (vs. stripe absent or incomplete) and total gill rakers 32–33 (vs. 36–40).

Etymology. The specific epithet, from the Greek psilos (bare, smooth, naked), is in reference to the smooth lower margin of the preopercle, and the numerous missing scales of the holotype due to trawl abrasion.

Distribution. ( Fig. 24 ) Western Australia between about 19°-14°S, where trawled in about 360‒ 440 m.

Figures

FIGURE 9. Frontal view of teeth in selected species of Owstonia (note widely spaced, spike-like, symphyseal, dentary teeth in C and D): A, O. ainonaka, AMS I. 33437 – 002, 213 mm SL; B, O. kamoharai, CSIRO 3596, 282 mm SL; C, O. psilos, NTM S. 12608 – 002, 75 mm SL; D, O. simotera, USNM 276514, 65 mm SL; E, O. simotera, SAIAB 605, 298 mm SL (photo by Ofer Gon, © SAIAB); F, O. weberi, ANSP 146627, 317 mm SL.

FIGURE 24. Distributions of selected species of Owstonia based on specimens examined, except records of O. mundyi from Kingman Reef based solely on submersible videos, and possibly could have been misidentifications of O. hawaiiensis.

FIGURE 64. Owstonia psilos, paratype, NMV A. 29664 – 004, 64 mm SL, Western Australia. Photograph by Martin F. Gomon.

FIGURE 65. Owstonia psilos, holotype, NMV A. 29673 ‒ 004, 82 mm SL, Western Australia. Photograph by Sandra J. Raredon.

FIGURE 66. Owstonia psilos, paratype, NMV A. 29733 – 007, 125 mm SL, Western Australia; insert part of dorsal fin showing traces of dark blotch. Photograph by Sandra J. Raredon.