Owstonia nigromarginata (Fourmanoir)

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 : 71-72

Owstonia nigromarginata (Fourmanoir)

( Figure 60 )

Sphenanthias nigromarginatus Fourmanoir, 1985:40 , fig. 4 (original description; Philippines, 14°0.1'N, 120°17.1'E, 184‒186 m, MUSORSTOM II, sta. 2).

Material examined. 2 specimens 65–68 mm SL as follows: MNHN 1982‒1251 (68), holotype, Philippines, 14°0.1'N, 120°17.1'E, 184‒186 m, MUSORSTOM II, sta. 2, 20 Nov. 1980 ; MNHN 1982‒1252 (1, 65), paratype, same data as holotype .

Diagnosis. A species of Owstonia with LL pattern type 1; unique in having a black stripe anteriorly on dorsal fin that tapers posteriorly and extends from distal third of 1st spine to the tip of 4th soft ray.

Description. (When 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 ray 16. Dorsal fin III, 21; anal fin I, 13; pectoral 19‒20; gill rakers 16 + 28 = 44 (14 + 26 = 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 35–37; nape scaly and cheek scale rows 3. Lower limb margin of preopercle with about 8–10 small spines. Papillae in slight depression behind tip of premaxillary ascending processes 4, all papillae nearly equally sized with lateral pairs more closely spaced together, except the paratype with one anterior papilla missing on one side. Teeth in outer row of each premaxilla 15/18 (17/18); 1 or 2 inner teeth anteriorly. Teeth in lateral row of each dentary 9; symphyseal teeth 3–4, spike-like, and with 1–2 inner teeth anteriorly. Pelvic fin probably sexually dimorphic, extending posteriorly to anal-fin soft ray 8 in unsexed holotype (between rays 3–4 in slightly smaller, but unsexed paratype). Caudal fin lanceolate. Caudal fin 1.8‒(broken) times in SL; head 3.4‒3.6 times in SL; body depth at anal-fin origin 3.7‒4.4 times in SL.

Color pattern in alcohol: Anterior part of dorsal fin with narrow, black, distal stripe extending from spine 1 to soft ray 4; membrane connecting maxilla and premaxilla with prominent black stripe extending to near anterior end of premaxilla, and nner membrane covering posterior part of dentary also black. Fourmanoir (1985) recorded the dominant color of O. nigromarginata as pink, including the dorsal fin.

Proportions of 68 mm SL holotype are given first, followed by those of the 65 mm specimen (in parentheses) as percentages of SL: predorsal length 26.7(--); preanal length 59.9 (55.9); dorsal-fin base 63.5 (62.0); anal-fin base 31.8 (30.5); pelvic-fin length 53.7 (41.2); caudal-fin length 55.4 (broken off); body depth at anal-fin origin 21.8 (22.8); head length 27.9 (29.2); upper jaw length 15.3 (15.5); upper jaw depth 7.8 (6.7); orbit diameter 12.6 (11.9). As percentages of head length: upper jaw length 54.7 (53.2); orbit diameter 45.3 (40.8).

Comparisons. Other species with LL pattern type 1 and black pigment on the dorsal fin anteriorly differ in having melanophores extending to base of fin. The holotype of Owstonia doryptera possibly has dorsal-fin pigmentation similar to that of O. nigromarginata but differs in having LL pattern type 3 and a short pelvic fin extending only to anal-fin origin (vs. pelvic fin extending to anal-fin soft ray 8 in holotype and between rays 3‒4 in paratype).

Etymology. A combination of the Latin nigro (black) and marginatus (margin) in reference to the black stripe anteriorly on the distal margin of the dorsal fin.

Distribution. ( Fig. 23 ) Known only from the Philippine type locality where trawled in 184‒ 186 m.

Remarks. Fourmanoir (1985) listed only two specimens of Sphenanthias nigromarginatus , which he recorded as 67 and 68 mm SL, and designated the larger specimen as the holotype. He recorded the number of anal-fin rays as I, 14 but examination of a radiograph of the holotype and our count of the paratype reveals that both specimens actually have only I, 13 anal-fin rays.

Figures

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

FIGURE 60. Owstonia nigromarginata, holotype, MNHN 1982 ‒ 1251, 68 mm SL, holotype, Philippines. After Fourmanoir, 1985, fig. 4.