Owstonia japonica Kamohara

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 : 56-58

Owstonia japonica Kamohara

( Figures 43−45 )

Owstonia japonica Kamohara, 1935:133 , fig. 2 (original description; off Mimase, near Kôchi Prov., Tosa, Japan; depth 80 fms [146 m]); Endo et al., 2015:[7] and 2016:37 (comparative material 19 specimens, 101–157 mm SL, listed from Japan).

Owstonia grammodon (non Fowler). Okada and Suzuki, 1956:185, fig. 1 (misidentification, osteological description); Kamoharai, 1961:1 (considered to be a synonym of O. japonica ); Shiino, 1972:116 (misidentification, common name "White-edged jawfish"); Machida in Masuda et al., 1984:201, Pl. 192-F (misidentification, brief description, color photograph); Nakabo, 2002:914 (misidentification, diagnosis, in pictorial key); Shinohara and Matsuura, 1997:306 (misidentification, listed in checklist, Suruga Bay; Japanese name Soko-amadai-modoki).

Material examined. 13 specimens, 88‒174 mm SL, all from Japan: ANSP 151948 (2, 136‒143), Kochi Pref., Mimase fish market, 31 Oct. 1980 ; ASIZ P.71559 (3, 160–169), Kochi City, Japan, 25°3"N, 121°56'W, H. Endo ; BSKU 92331 (1, 142), off Kochi ; CAS 133927 (1, 141), CAS 133931 (1, 141), CAS 133935 (1, 174) and CAS 133937 (1, 148), all Kochi Pref., Kochi, T. Kamohara, 1937; NSMT-P 32720 (2, 88‒137), Shikoku, Kochi Pref., Tosa Bay ; NSMT-P 46724 (1, 156), Shikoku, Tosa Bay, K. Matsuura, Feb. 1984 .

Diagnosis. A species of Owstonia with LL pattern type 1 (one specimen, discussed below, is exceptional in having a lateral line with a nape loop); dorsal fin III, 21; anal fin I, 13‒14 (typically 14); lower limb margin of preopercle with 5–8 spines varying from embedded under skin and difficult to see to partially exposed and moderately large; teeth in outer row of each premaxilla 14‒23; in fresh specimens median fins with white margins and dorsal and caudal fins with narrow, red, submarginal stripe.

Description. A species of Owstonia with LL pattern type 1 ( Fig. 6 A) that typically 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 19–21. (CAS 133935, 1 of 13 specimens, is exceptional in having a lateral line with a complete nape loop but otherwise agrees perfectly with O. japonica ). Dorsal fin III, 21; anal fin I, 13‒14 (rarely 13); pectoral fin 20‒22; gill rakers 13‒16 + 26‒31 = 41‒47. 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 45‒52; nape scaly and cheek scale rows 5‒7. Lower limb margin of preopercle with 5–8 spines varying from embedded under skin and difficult to see to partially exposed and moderately large. ( Okada and Suzuki, 1956, fig. 1, include a good drawing of the preopercular spines of O. japonica , which they misidentified as O. grammodon .) 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 14‒23; 1 or 2 inner teeth anteriorly. Teeth in lateral row of each dentary 8‒12, including 1−4 teeth at anterior end that continue behind symphyseal teeth in larger specimens; symphyseal teeth 4‒6, blunt and conical, and with 1–3 very small inner teeth anteriorly. Depressed pelvic fin extending posteriorly only to anal-fin origin. Caudal fin lanceolate. In 10 specimens, 88‒174 mm SL, caudal fin 1.6‒2.2 times in SL; head 3.5‒4.0 times in SL; body depth at anal-fin origin 3.7‒4.4 times in SL.

Color pattern in alcohol: Adults with anterior part of dorsal fin uniformly pale; 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. In fresh specimens, interradial membranes of dorsal fin with dark reticulations, median fins with white margins and dorsal and caudal fins with narrow, dark red submarginal stripe. Kamohara (1934) noted that in life Owstonia japonica is uniformly reddish and the "vertical fins finely adorned with many small white vermiculate markings, the margin being whitish."

Proportions of 13 specimens 88‒174 mm SL mm SL, as percentages of SL: predorsal length 24.3‒28.7; preanal length 51.2‒66.2; dorsal-fin base 60.5‒77.6; anal-fin base 24.4‒41.3; pelvic-fin length 25.2‒32.6; caudalfin length 43.8‒70.3; body depth at anal-fin origin 22.6‒36.0; head length 24.9‒29.5; upper jaw length 13.0‒16.0; upper jaw depth 5.7‒7.3; orbit diameter 10.4‒13.9. As percentages of head length: upper jaw length 47.7‒63.3; orbit diameter 38.7‒52.1.

Comparisons. Owstonia scottensis and O. dispar , the only species with most of the diagonostic characters of O. japonica , differ (characters of O. japonica in parentheses) as follows: O. scottensis has a larger orbit diameter 15–17.5% SL (vs. 10.4–13.9%), and in fresh specimens median fins uniformly red (vs. median fins with white margins and dorsal and caudal fins with narrow, red submarginal stripe); O. dispar has fewer cheek scale rows, 3 (vs. 5–7), longer upper jaw at similar sizes, 16% SL (vs. 14.4% SL), and each dentary with 3 spike-like symphyseal teeth (vs. 4‒6 blunt, conical, symphyseal teeth).

Etymology. The specific epithet is the Latinized version of Japan, the type locality of the species.

Distribution. ( Fig. 23 ) Known only from vicinity of Shikoku Island, Japan where trawled in at least 146 m.

Remarks. The original description includes data for three specimens (145–225 mm TL), with no particular individual specified as the holotype other than the statement "the type is deposited at the Biological Laboratory, Kôchi College." Subsequently, Kamohara (1961:1) stated that the holotype (BSKU) was lost.

One specimen of Owstonia japonica ( Fig. 45 ) is atypical in having a type 3 lateral-line pattern with a complete nape loop but all its other characters agree well with typical specimens of O. japonica . This is one of several reasons why we do not use lateral-line patterns as the basis for generic groupings of owstoniine fishes. Owstonia totomiensis , the only other species known from Japan with a complete lateral-line nape loop, differs most obviously in lacking cheek scale rows.

Records of O. grammodon from Japan appear to have been based on misidentifications of O. japonica (see above synonymies and Remarks in O. grammodon account.).

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

FIGURE 43. Owstonia japonica, BSKU 92331, 142 mm SL, Japan, off Kochi. Photograph courtesy Hiromitsu Endo.

FIGURE 44. Owstonia japonica, ANSP 151948, 143 mm SL, Japan, off Kochi. Photograph by Sandra J. Raredon.

FIGURE 45. Owstonia japonica, CAS 133935, 174 mm SL, Japan off Kochi. Photograph by Sandra J. Raredon.