Owstonia elongata, 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 : 46-47

Owstonia elongata new species

( Figure 35 )

Holotype. MNHN 2014–2934, 111 , Vanuatu, 15°7'58.8"S, 166°52'58.8"E, beam trawl in 191–248 m, Exped. MUSORSTOM 8, sta. 118 , 9 Oct. 1994.

Paratypes. 10 specimens, 63–117 mm SL: Vanuatu MNHM 2008–1350 , (3, 80–117) and USNM 432454 (2, 110‒111), taken with the holotype . New Caledonia MNHN 2001–3368 (4, 48–88) 20°57'S, 165°34'58.8"E, beam trawl in 205–212 m, Exped. BATHUS 1, sta. 667, 14 Mar. 1993 ; MNHN 2004–2445 (1, 63), 21°52'12"S, 166°49'58.8"E, beam trawl in 255–360 m, Exped. BATHUS 1, sta. 646, 10 Mar. 1993.

Diagnosis. A species of Owstonia with LL pattern type 1; dorsal fin IV, 24–26; oblique body scale rows in mid-lateral series 30–33; total gill rakers 36–40; body depth at anal-fin origin 10.8–14.0% SL; precaudal vertebrae and pterygiophores anterior to 1st haemal spine 16 and 8 respectively.

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 20 (22). Dorsal fin IV, 25 (24–26); anal fin I, 19 (I, 18–19, except 1 specimen with II, 17); pectoral fin 17 (17–19); gill rakers 16 (15–16) + 28 (26–30) = 43 (41–46). Vertebrae: precaudal 16, caudal 16, total 32; analfin pterygiophores anterior to 1st haemal spine 8 ( Fig. 7 E). Oblique body scale rows in mid-lateral series about 30– 33; nape scaly and cheek scale rows 3 or 4, Fig. 12 C. Lower limb margin of preopercle with 5–8 spines ( Fig. 8 B). Papillae in slight depression behind tip of premaxillary ascending processes 4, arranged in 2 closely spaced but distinct pairs. Teeth in outer row of each premaxilla 22/27 (18–23); no inner teeth anteriorly. Teeth in lateral row of each dentary 18/20 (12–17), including 1−3 at anterior end that continue in a row behind symphyseal teeth; symphyseal teeth 4−5, short and conical, and with 3–4 smaller inner teeth anteriorly. Pelvic fin possibly sexually dimorphic, depressed fin length extending to posterior margin of anus or to anal-fin soft ray 2. Caudal fin lanceolate. In 6 specimens, 87.5‒117.5 mm SL, caudal fin 1.7‒2.9 times in SL; head 5.1‒6.3 times in SL; body depth at anal-fin origin 7.1‒9.1 times in SL.

Color pattern in alcohol: Adults with 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. Life coloration unknown.

Proportions of 110 mm SL holotype are given first, followed by those of 4 paratypes, 88–117 mm SL (in parentheses), as percentages of SL: predorsal length 16.6 (15.6‒18.8); preanal length 38.1(36.0‒42.2); dorsal-fin base 73.0 (69.3‒74.5); anal-fin base 50.7 (47.7‒54.0); pelvic-fin length 22.5 (15.9‒22.5); caudal-fin length 50.4 (34.1‒50.4); body depth at anal-fin origin 11.4 (10.8‒14.0); head length 18.9 (15.8‒19.7); upper jaw length 8.5 (7.6‒8.8); upper jaw depth 3.7 (3.6‒4.4); orbit diameter 7.1 (6.5‒7.6). As percentages of head length: upper jaw length 45.1 (44.0‒47.9); orbit diameter 37.6 (38.6‒40.9).

Comparisons. Owstonia elongata is superficially most similar to O. taeniosoma in having a relatively small head and low numbers of oblique body scale rows in mid-lateral series and cheek scales, but differs (characters of O. elongata in parentheses) as follows: dorsal-fin spines III (vs. IV), deeper body with depth at anal-fin origin 14.5–18.4% SL (vs. 10.8–14.0%), more total gill rakers 41–46 (vs. 36–40), and fewer precaudal vertebrae and pterygiophores anterior to 1st haemal spine, 15 and 6–7 respectively (vs. 16 and 8). Owstonia fallax , O. hastata and O. sibogae are also superficially similar in having IV dorsal-fin spines and relatively few oblique body scale rows in mid-lateral series but differ in having fewer precaudal vertebrae 12–13 (vs. 16) and pterygiophores anterior to 1st haemal spine 4–5 (vs. 8), and a deeper body depth at anal-fin origin 17.5–25.8% SL (vs. 10.8–14.0%). Etymology. From the Latin elongatus (prolonged), in reference to the elongate body of this species. Distribution. ( Fig. 25 ) Known only from New Caledonia and Vanuatu where trawled in depths of 191‒248, 205‒212 and 255‒ 360 m.

Remarks. One 87-mm SL specimen (MNHN 2001−3368) is exceptional in having two anal-fin spines. This is the only case of a species of Owstonia exhibiting intraspecific variation in number of anal-fin spines (see Table 4).

Figures

FIGURE 7. Radiographs of selected species of Owstonia to show number of anal-fin pterygiophores anterior to first haemal spine (indicated by white arrowhead): A, O. japonica, NSMT P. 32720, 137 mm SL, Japan; B, O. sarmiento, AMS I. 25826 – 0 0 7, 76 mm SL, eastern Australia; C, O. tosaensis, CSIRO H. 6431 – 03, 155 mm SL, western Australia; D, O. taeniosoma, BSKU 75249, 169 mm SL, Japan; E, O. elongata, MNHN 2014 ‒ 29345, 111 mm SL, New Caledonia. Number of anterior analfin pterygiophores in these specimens are: A = 2, B = 3, C = 4, D = 6 and E = 8.

FIGURE 8. Margins of preopercle lower limb (not drawn to scale), showing relative spine development in selected species of Owstonia: A, O. contodon, USNM 438013, 162 mm SL; B, O. elongata, USNM 432454, 110 mm SL; C, O. geminata, ASIZP 68128, 79 mm SL; D, O. maccullochi, holotype (right side reversed), AMS IA. 5815, 156 mm SL; E, O. maccullochi, NTM S. 11765 − 001, 146 mm SL; F, O. rhamma, holotype, MNHN 1995 – 0005, 102 mm SL; G, O. sarmiento, ANSP 165126, 82 mm SL; H., O. scottensis, CSIRO H. 7136 − 04, 103 mm SL; I, O. sibogae, ANSP 152035, 113 mm SL; J, O. taeniosoma, CAS 133928, 126 mm SL; K, O. tosaensis, ANSP 153169, 100 mm SL; L, O. weberi, ZMUC P. 531552, 127 mm SL.

FIGURE 12. Cheek scales on left side in selected species of Owstonia: A, O. ainonaka, AMS I. 33437, 213 mm SL; B, O. doryptera, USNM 93166, 65 mm SL; C, O. elongata, MNHN 2008 – 1350, 110 mm SL; D, O. grammodon, USNM 93167, 67 mm SL; E, O. kamoharai, NTM S. 12631 – 017, 206 mm SL; F, O. kamoharai, CSIRO H. 2099 – 007, 408 mm SL; G, O. maccullochi, AMS I. 25806 ‒ 012, 141 mm SL; H, O. raredonae, SAIAB 82406, 97.4 mm SL; I, O. sibogae, CAS 33843, 126 mm SL.

FIGURE 25. Distributions of selected species of Owstonia based on specimens examined.

FIGURE 35. Owstonia elongata, holotype, MNHN 2014 – 2934, 111 mm SL, Vanuatu. Photograph by Sandra J. Raredon.