Owstonia crassa, 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 : 42-43

Owstonia crassa new species

( Figures 31 , 32 )

Holotype. MNHN 2002−3164, 157 mm SL, New Caledonia, 22°6'S, 167°10'1.2"E, beam trawl in 500–550 m, Exped. MUSORSTOM 4, sta. 242, 3 Oct. 1985.

Paratypes. 6 specimens, 54−190 mm SL: New Caledonia MNHN 2014−2932 , (1, 81), 21°13'58.8"S, 165°55'12"E, beam trawl in 490–530 m, Exped. Bathus 1 sta. 657 ; MNHN 2002−3190 (1, 78), 22°9'S, 167°12'18"E, beam trawl in 470–480 m, Exped. MUSORSTOM 4, sta. 124, 3 Oct. 1985; MNHN 2014−142 (1, 86), no precise New Caledonia locality . Solomon Islands MNHN 2014−1366 (1, 190), 10°26'S, 161°22'E, Salomon Boa 3 cruise, R/ V Alis sta. 2837, beam trawl in 381–422 m, 22 Sep. 2007 ; MNHN 2006−298 (2, 54−81), 8°32'13.2"S, 157°48'14.4"E, beam trawl in 380–537 m, Exped. Solomon 2, sta. 2272, 5 Nov. 2004.

Diagnosis. A species of Owstonia with LL pattern type 1; dorsal fin III, 19–21; anal fin I, 12–13; lower limb margin of preopercle without spines; prominent dark premaxillary stripe; adults with 15–22 teeth in outer row of each premaxilla.

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 posttemporal sensory canal near anterodorsal margin of gill opening, curves upward and backward then continues posteriorly just below dorsal-fin base to soft rays 14 (15–17). Dorsal fin III, 20 (19–21); anal fin I, 13 (12–13); pectoral fin 20 (20–21); gill rakers 14 + 26/27 (13–15) + (24–27) = 40/41 (37–42). 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 45–47; nape scaly and cheek scale rows 4–7. Lower margin of preopercle without spines. Papillae in slight depression behind tip of premaxillary ascending processes 4, arranged in 2 closely spaced pairs with the posterior pair elongate in several specimens ( Fig. 14 A); two of the paratypes (MNHN 2014–142 and MNHN 2014–2932) also have small flaps on the anterior pair of papillae. When mouth completely closed upper jaw extending to or slightly beyond vertical from posterior margin of orbit. Teeth in outer row of each premaxilla 18/22 (15–21), with anterior teeth relatively short and middle ones longest; 2 smaller inner teeth usually present. Teeth in lateral row of each dentary 9/11 (8‒12), including 3−5 at anterior end that continue in a row behind symphyseal teeth in larger specimens; symphyseal teeth 3/5 (3‒4), short and spike-like, and with 1–2 smaller inner teeth anteriorly. Pelvic fin short, depressed fin extends only to anal-fin origin. Caudal fin lanceolate. In six specimens 83‒169 mm SL, caudal fin 1.9‒2.8 times in SL; head 4.7‒6.0 times in SL; body depth at anal-fin origin 4.6‒6.9 times in SL.

Color pattern in alcohol: Proximal half of interradial membranes of dorsal-fin soft rays 1–4 or 5 black in five paratypes (54‒86 mm SL), persisting as dusky smudges smaller than pupil diameter in holotype and absent in largest paratype (190 mm SL); membrane connecting maxilla and premaxilla with prominent black stripe extending to near anterior end of premaxilla, and inner membrane covering posterior part of dentary also black, at least in adults. Life coloration unknown.

Proportions of 157 mm SL holotype are given first, followed by those of 5 paratypes, 78–190 mm SL (in parentheses), as percentages of SL: predorsal length 28.7 (28.8‒31.3); preanal length 56.2 (56.7‒62.3); dorsal-fin base 62.2 (53.7‒65.6); anal-fin base 28.3 (26.7‒31.9); pelvic-fin length 25.4 (24.5‒28.0); caudal-fin length 53.0 (36.2‒51.0); body depth at anal-fin origin 27.4 (26.5‒30.5); head length 31.5 (29.8‒32.8); upper jaw length 18.5 (16.4‒18.1); upper jaw depth 9.3 (7.6‒9.0); orbit diameter 14.0 (12.9‒15.9). As percentages of head length: upper jaw length 58.6 (51.0‒59.5); orbit diameter 44.5 (43.0‒48.3).

Comparisons. Three other species, Owstonia grammodon , O. hawaiiensis and O. ignota , have the same first four diagnostic characters of O. crassa but differ (characters for O. crassa given in parentheses) as follows: all three species have more outer premaxillary teeth, 33–39 (vs. 15–22) and adults and small individuals have pale dorsal fins (vs. smaller paratypes, 54–86 mm SL, of O. crassa with a prominent dark blotch between dorsal-fin soft rays 1–4 or 5, persisting as faint dusky smudges in holotype but absent in largest paratype); Owstonia hawaiiensis and O. ignota also differ in lacking a premaxillary stripe (vs. prominent premaxillary stripe). Owstonia psilos is superficially similar but consistently has anal fin I, 14 (vs. I, 12–13) and premaxillary stripe absent, incomplete or very faint (vs. prominent dark stripe).

Etymology. The specific epithet is from the Latin crassus (thick, fat or stout), in reference to the general appearance of the holotype.

Distribution. ( Fig. 23 ) Known only from New Caledonia and the Solomon Islands where trawled between 380– 550 m.

Figures

FIGURE 14. Arrangement and relative sizes of papillae in slight depression at tip of ascending premaxillary processes (dorsal view, anterior to right) in selected species of Owstonia: A, O. crassa, MNHN 2002 – 3720; B., O. dispar, MNHN 2002 – 3720; C, O. maccullochi, CSIRO H 5946 – 20; D, O. mundyi, USNM 427880; E, O. sarmiento, NTM S. 11782 – 001; and F, O. totomiensis, NSMT – P 77978.

FIGURE 23. Distributions of selected species of Owstonia based on specimens examined.

FIGURE 31. Owstonia crassa, holotype, MNHN 2002 − 3164, 157 mm SL, New Caledonia. Photograph by Sandra J. Raredon.

FIGURE 32. Owstonia crassa, MNHN 2006 ‒ 0298, 54 mm SL, Solomon Islands. Photograph by Sandra J. Raredon.