Owstonia nudibucca, 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 : 72-74

Owstonia nudibucca new species

( Figures 61‒63 )

Owstonia totomiensis . Gloerfelt-Tarp and Kailola, 1984:229, unnumbered color photo (misidentification; brief description; ANSP catalog number of photographed fish [holotype] listed on p. 347).

Holotype. ANSP 151993, 224 mm SL, Andaman Sea , Mentawai Islands, off east coast of Siberut Island, 1°22'S, 98°37'E, depth not recorded, M/ V Jurong, via P.J.P. Whitehead, 1980.

Paratypes. 2 specimens, 93‒288 mm SL. SAIAB 201332 (1, 288) and SAIAB 201333 (1, 93), Andaman Sea , off Gulf of Mottama (Martaban), 14°31'12"N, 93°44'24"E, 268.5 m, R/V " Dr. Fridtjof Nansen " sta. 58, Peter N. Psomadakis, 9 May 2012.

Diagnosis. A species of Owstonia with naked nape and cheeks; LL pattern type 3, including a short vertical side branch slightly anterior to dorsal-fin origin ( Fig. 6 D); oblique body scale rows in mid-lateral series 38‒42; caudal peduncle depth 2.3‒1.7 times in its length.

Description. (Where counts vary, those of the paratypes are given in parentheses.) A species of Owstonia with LL type 3, in which lateral line does not contact posttemporal sensory canal near anterodorsal margin of gill opening, continues posteriorly just below dorsal-fin base and anteriorly where it makes a complete loop across nape and also has the horizontal section of lateral line with a short ventral side branch slightly anterior to dorsal-fin origin; lateral line ends below dorsal-fin soft rays 16-17. Dorsal fin III, 21; anal fin II, 14; pectoral fin 22 (21‒22); gill rakers 18 + 29/31 = 47 or 49 (16‒18 + 27‒32 = 45‒50. 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 38/44 (ca. 50); nape and cheeks naked. Papillae in slight depression behind tip of premaxillary ascending processes 4, arranged in 2 almost equally spaced pairs. Lower limb margin of preopercle with about 7 or 8 (6‒7) spines. Teeth in outer row of each premaxilla 17/18 (18‒23), anterior 8−11 teeth moderately elongate with blunt tips; no inner teeth anteriorly. Teeth in lateral row of each dentary 14/15 (12–17); symphyseal teeth 3/4 (4‒5), moderately short, spike-like (all other dentary teeth smaller with pointed tips), and with 1 or 2 (1) much smaller inner teeth anteriorly. Depressed pelvic fin extending to anal-fin origin (to soft ray 3 in larger paratype). Caudal fin lanceolate. In smallest to largest types, Caudal fin 1.6‒2.0 times in SL; head 3.2, 3.8, 4.0 times in SL; body depth at anal-fin origin 4.4, 5.1, 5.8 times in SL. Caudal peduncle depth 2.3 (2.4 and 1.6 in larger and smaller paratypes respectively) times in its length.

Proportions of 224 mm SL holotype are given first, followed (in parentheses) first by those of the 93 mm SL and then the 288 mm SL paratypes, as percentages of SL: predorsal length 22.7 (29.4‒22.3); preanal length 54.2 (54.1‒48.4); dorsal-fin base 61.4 (65.4‒63.4); anal-fin base 32.1 (29.7‒27.6); caudal peduncle length 17.4 (13.2‒20.0); caudal peduncle depth 7.5 (9.7‒8.2); pelvic-fin length 31.0 (23.7‒28.1); caudal-fin length 62.9 (50.5‒63.9); body depth at anal-fin origin 19.5 (22.9‒17.3); head length 26.3 (31.6–24.8); upper jaw length 13.4 (16.7‒14.0); upper jaw depth 6.2 (7.6‒5.0); orbit diameter 11.0 (15.4‒9.3). As percentages of head length: upper jaw length 50.8 (52.7‒56.5); orbit diameter 42.0 (48.9‒37.3).

Color pattern in alcohol: Dorsal fin of holotype with three faint traces of small dusky blotches between membranes of last spine and soft ray 4 (these blotches absent in largest paratype) and smaller paratype with interradial membranes between dorsal-fin spine 3 and soft ray 5 black; membrane connecting maxilla and premaxilla with prominent black stripe extending to near anterior end of premaxilla ( Fig. 15 B, 62‒63), and inner membrane covering posterior part of dentary also black.

In fresh specimens body and fins range from pink to red, paler below, with iris red; the largest paratype has at least the anterior half of the dorsal fin with a narrow, dark, red distal margin ( Fig. 61 ). Gloerfelt-Tarp and Kailola (1984) recorded the life coloration of the holotype as: "body and fins plain dark red; usually 3 dark brown patches over anterior dorsal fin membrane; black premaxillary groove."

Comparisons. Owstonia totomiensis , the only other species with naked nape and cheeks and LL pattern type 3, differs (characters of O. nudibucca in parentheses) in having horizontal section of the lateral line without a short ventral side branch slightly anterior to dorsal-fin origin (vs. short side branch present), more oblique body scale rows in mid-lateral series 50–60 (vs. 38–42), and caudal peduncle depth 1.3−1.7 (vs. 2.3‒3.0) times in its length.

Etymology. From the Latin nudus (bare, naked) and bucca (cheek), in reference to the naked cheeks.

Distribution. ( Fig. 22 ) Known from the Mentawai Islands off the east coast of Siberut Island, Indonesia and the Andaman Sea off Myanmar where trawled in 262‒ 269 m.

Remarks. A 55-cm TL (ca. 342 mm SL) specimen ( Fig. 62 ), photographed by Oddgeir Alvheim but not preserved, was collected from the Andaman Sea, off southern Myanmar (12°22'N, 96°51'E), trawled in 262 m, Dec. 2013. This specimen is notable for its narrow and elongate caudal peduncle (CP), depth of CP about 3.0 times in its length; measurements calculated from the photograph: CP depth 6.7 % and CP length 19.9% SL.

Figures

FIGURE 6. Diagrammatic illustrations of lateral-line patterns in selected species of owstonia: type 1 pattern: A (O. japonica); type 2 pattern: B, F (O. tosaensis), E (O. sarmiento); type 3 pattern: C, G (O. maccullochi), D (O. nudibucca); type 4 pattern: H (O. weberi). See text for detailed discussion of these patterns in owstoniines.

FIGURE 15. Premaxillary stripes in selected species of Owstonia: A, O. hastata, NTM S. 11779 – 002, 124 mm SL; B, O. nudibucca, ANSP 151993, 224 mm SL, Mentawai Islands; C, O. sibogae, CAS 32914, 96 mm SL, Philippines; D, O. ainonaka, AMS I. 33437 – 002, 213 mm SL. Photographs by Sandra J. Raredon.

FIGURE 22. Distributions of selected species of Owstonia based on specimens examined.

FIGURE 61. Owstonia nudibucca, paratype, SAIAB 201332, 288 mm SL, Andaman Sea, Gulf of Mottama. Photograph by Peter N. Psomadakis.

FIGURE 62. Owstonia nudibucca, not preserved, ca. 340 mm SL, Andaman Sea, off southern Myanmar. Photograph by Oddgeir Alvheim.

FIGURE 63. Owstonia nudibucca, holotype, ANSP 151993, 224 mm SL, Indonesia, Mentawai Is. Photograph by Sandra J. Raredon.