Owstonia simotera (Smith)

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 : 86-87

Owstonia simotera (Smith)

( Figures 76 , 77 )

Sphenanthias simoterus Smith, 1968:11 , fig. 1 & pl. 6, fig. C (original description; off Bazaruto, southern Mozambique, depth 260‒300 fms [= 475‒549 m]).

Owstonia simoterus Smith-Vaniz, 1986:728 , fig. 226.2 (brief description).

Material examined. 2 specimens, 65‒298 mm SL: SAIAB 605 (298) holotype of Sphenanthias simotera , southern Mozambique, off Bazaruto , 475–549 m, [date not given] ; USNM 276514 (1, 65), Mozambique Channel, off Delagoa Bay , 25°31.0'S, 33°26.5'E, 450‒455 m, R/ V Anton Bruun cruise 8, sta. 396B, 28 Sep. 1964 .

Diagnosis. A species of Owstonia with LL pattern type 1; cheek scale rows 7–10; lanceolate caudal fin; adults with large curved dentary canines ( Fig. 9 E).

Description. Data for holotype based on an x-ray, the original description, and observations of Ofer Gon and Phillip C. Heemstra; where counts differ, those of the smaller specimen 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 17/18 (15). Dorsal fin III, 21; anal fin I, 14; pectoral fin 22 (21); gill rakers 13 + 25= 38 (12 + 22 = 34). Vertebrae: precaudal 11, caudal 17, total 28; anal-fin pterygiophores anterior to 1st haemal spine 2. Oblique body scale rows in mid-lateral series approximately 50−60 (50), in contrast to "about 70" given in original description; nape scaly and cheek scale rows 11–12. Preopercle lower limb margin without spines. 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 23/23 (14), smaller specimen with anterior 3 or 4 teeth spike-like and no inner teeth anteriorly. Teeth in lateral row of each dentary about 10 (8); smaller specimen with 3 symphyseal, spike-like teeth ( Fig. 9 D), and 1 smaller inner tooth anteriorly. Smith’s (1968) description of the holotype states “In the lower jaw [anteriorly] on each side is a widely spaced cluster of sharp curved teeth in about 3 rows, about 10 similar teeth uniserial on each side of jaw, shorter posteriorly." Figure 9 E shows the large curved dentary canines and some broken-off premaxillary teeth on right side of holotype. Pelvic fin short in holotype, depressed fin extending posteriorly to slightly behind anus. Caudal fin of adults lanceolate. Holotype with caudal fin 3.6 times in SL; head 3.5 times in SL; body depth at anal-fin origin 3.3 times in SL.

Color pattern in alcohol: Holotype with dark specks and scattered streaks on dorsal and anal fins; smaller specimen with dark blotch in dorsal fin on interradial membranes between spine 2 and soft ray 5. Membrane connecting maxilla and premaxilla with black stripe extending to near anterior end of premaxilla, and inner membrane covering posterior part of dentary pale. Smith (1968) recorded the life color as "body and fins clearly red or crimson, with dark spots on the body and specks and streaks up the membrane of the unpaired fins. There are signs of a darker red submarginal line along the dorsal."

Proportions of 298 mm SL holotype, with selected values for the 65 mm SL specimen given in parentheses, as percentages of SL: predorsal length 27.9; preanal length 53.8; dorsal-fin base 62.1; anal-fin base 30.8; pelvic-fin length 21.4 (22.6); caudal-fin length 27.9 (broken); body depth at anal-fin origin 30.1 (23.5); head length 28.2 (31.7); upper jaw length 16.5 (18.7); upper jaw depth 7.7 (8.3); orbit diameter 9.4 (13.9). As percentages of head length: upper jaw length 58.7 (59.1); orbit diameter 33.3 (43.8).

Comparisons. The allopatric Owstonia kamoharai is similar to O. simotera in having a relatively large numbers of cheek scale rows (11-12 vs. 7-10), dorsal fin with red marginal or submarginal stripe in life, other nearly identical meristic characters, and a short pelvic fin that does not extend behind anus but differs (characters of O. simotera in parentheses) as follows: caudal fin of adults rounded posteriorly and longer, 33.7-40% SL (vs. lanceolate and shorter, 27% SL) and no caniniform dentary teeth (vs. with large, curved, dentary canines ( Fig. 9 E).

Other western Indian Ocean species with LL pattern type 1, in addition to having lanceolate caudal fins and fewer cheek scale rows 2‒7 (vs. cheek scale rows 7‒10), further differ (characters for O. simotera in parentheses) as follows: O. similis has fewer upper gill rakers 10 (vs. 12–13) and dorsal fin interradial membranes between spine 2 and soft ray 3 with heavy concentration of melanophores (vs. smaller specimen with membranes between spine 2 and soft ray 5 black, and holotype with dark specks and streaks on dorsal fin membranes); O. whiteheadi has lower limb margin of preopercle with moderate to strong spines (vs. preopercular margin without spines) and fewer oblique body scale rows in mid-lateral series, 39–41 (vs. ca. 50−60); O. raredonae has fewer dorsal- and anal-fin soft rays, 19 and 12 respectively (vs. 21 and 14); O. lepiota has more oblique body scale rows in mid-lateral series 95 (vs. ca. 50–60), nape naked (vs. nape scaly) and more dorsal- and anal-fin rays, III, 23 and II, 15 respectively (vs. III, 21 and I, 14).

Etymology. From the Latin simoter (snub-nosed).

Distribution. ( Fig. 27 ) Known only from the western Indian Ocean off Mozambique where holotype reported from 475–549 m and the other specimen trawled in 450– 455 m.

Remarks. Smith (1956) reported that O. simotera has a series of about 70 scales from head to caudal base, and he incorrectly recorded the vertebrae as 11 + 15 (actually 11 + 17). Many body scales on holotype are missing and arranged in irregular rows making it very difficult to accurately count the number of mid-lateral scale rows. At our request, Ofer Gon and Phil Heemstra independently attempted to count oblique horizontal scale rows of the holotype and concluded that a range of approximately 50−60 is more reasonable.

Figures

FIGURE 9. Frontal view of teeth in selected species of Owstonia (note widely spaced, spike-like, symphyseal, dentary teeth in C and D): A, O. ainonaka, AMS I. 33437 – 002, 213 mm SL; B, O. kamoharai, CSIRO 3596, 282 mm SL; C, O. psilos, NTM S. 12608 – 002, 75 mm SL; D, O. simotera, USNM 276514, 65 mm SL; E, O. simotera, SAIAB 605, 298 mm SL (photo by Ofer Gon, © SAIAB); F, O. weberi, ANSP 146627, 317 mm SL.

FIGURE 27. Distributions of selected species of Owstonia based on specimens examined.

FIGURE 76. Owstonia simotera, holotype, SAIAB 605, 298 mm SL, Mozambique, off Bazaruto. After Smith, 1968, plate 6 c, image from original photographic negative courtesy of Ofer Gon, © SAIAB.

FIGURE 77. Owstonia simotera, USNM 276514, 65 mm SL, Mozambique Channel. Photograph by Sandra J. Raredon.