Owstonia mundyi, 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 : 68-70

Owstonia mundyi new species

( Figures 56‒58 )

Holotype. USNM 427880, 128 mm SL, gravid female, Kiribati (Line Islands), off southwest point of Christmas Island, shrimp trawl in 150 fms [= 274 m], Townsend Cromwell Cruise 60, sta. 53, R. Barkley et al., 22 Aug. 1972.

Paratypes. USNM 427319 (2, 121− 125 mm SL), both gravid females, same data as holotype.

Diagnosis. A species of Owstonia with LL pattern type 1; nape and cheeks without scales; oblique body scale rows in mid-lateral series 97–108.

Description. (When counts vary those of 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 20–23. Dorsal fin III, 23; anal fin I, 15–16; pectoral fin 17–18; gill rakers 13+22/23 (12+23–24). Vertebrae: precaudal 11, caudal 18, total 29; anal-fin pterygiophores anterior to 1st haemal spine 3. Oblique body scale rows in mid-lateral series about 106/108 (97–105); nape and cheeks naked. Lower margin of preopercle without spines. Papillae in slight depression behind tip of premaxillary ascending processes 4, arranged in 2 almost equally spaced pairs; each papilla is slightly tapered vertically and capped with a small flap, which condition is more apparent in the holotype ( Fig. 14 D). Teeth in outer row of each premaxilla 20/22 (19–24); 2–3 inner teeth anteriorly. Teeth in lateral row of each dentary 9‒15; symphyseal teeth 2/3 (2−3), small and conical, and with 2–3 small inner teeth anteriorly. Pelvic fin apparently sexually dimorphic, depressed fin short and extending only to anal-fin origin in the three gravid type specimens but much longer in a male tentatively identified as O. mundyi (see Distribution and Remarks). Caudal fin lanceolate. Caudal fin 2.1‒2.4 times in SL; head 3.4‒3.9 times in SL; body depth at anal-fin origin 5.0‒5.2 times in SL.

Color pattern in alcohol: Dorsal fin uniformly pale; membrane connecting maxilla and premaxilla with prominent black stripe that extends nearly to end of ascending process, and inner membrane covering posterior part of dentary also black. Based on videos of individuals at Kingman Reef tentatively identified as O. mundyi ( Figs. 57 , 58 ), upper part of head and body red, becoming paler below; and presumed male (see "Distribution") with distal margin of dorsal fin and elongate pelvic-fin soft ray white. Caudal and anal fins pale with narrow red margins and dorsal fin with narrow submarginal red stripe, wider posteriorly. Owstonia mundyi and O. hawaiiensis appear to have virtually identical life coloration.

Proportions of 128 mm SL holotype are given first, followed by those of the 121–125 SL paratypes (in parentheses), as percentages of SL: predorsal length 25.1 (22.9–26.0); preanal length 50.7 (50.6–52.2); dorsal-fin base 64.6 (64.4–64.6); anal-fin base 36.0 (37.0–40.0); pelvic-fin length 21.9 (21.9–24.0); caudal-fin length 42.0 (42.0–47.0); body depth at anal-fin origin 19.4 (19.3–19.6); head length 28.4 (25.5–27.5); upper jaw length 12.3 (12.2–12.3); upper jaw depth 5.3 (4.9–5.5); orbit diameter 10.4 (9.4–11.6). As percentages of head length: upper jaw length 43.4 (40.2–43.7); orbit diameter 36.5 (37.0–42.3).

Comparisons. The western Indian Ocean O. lepiota also lacks nape scales and has a high number (95) of oblique body scale rows in mid-lateral series but differs in having 5–6 cheek scale rows (vs. naked cheek) and analfin rays II,15 (vs. I, 15‒16 in O. mundyi ). Owstonia nudibucca and O. totomiensis , the only other congeners that lack cheek scales, differ from O. mundyi most obviously in having LL pattern type 3 and fewer oblique scale rows in mid-lateral series, 38‒60 (vs. 97‒108).

Etymology. Named for Bruce C. Mundy, NOAA National Marine Fishery Service, Pacific Islands Fisheries Science Center, who arranged for us to receive the type specimens of this species and called our attention to important video frame grabs in support of his important submersible observations on Owstonia spp.

Distribution. ( Fig. 24 ) Specimens came only from the Christmas Island type locality, and presumably the same species has also been observed and filmed ( Figs. 57 , 58 ) at Kingman Reef, 6°25.702'N, 162°26.338'W. Specimens were trawled in about 274 m at the type locality and observed in 342 m at Kingman Reef. We tentatively identify the Kingman Reef species as O. mundyi because Kingman Reef and Kiribati are both in the Line Island Group. However, we note that the life colors of the presumed female ( Fig. 57 ) are remarkably similar to that of O. hawaiiensis ; it also agrees in having a relatively short caudal fin, in contrast to the presumed male O. mundyi ( Fig. 58 ) which appears to have a much longer caudal fin than that of a male O. hawaiiensis ( Fig. 41 ); calculated caudal-fin lengths of the two fish, based on the video images ( Figs. 41 and 58 ), are approximately 39% SL and 47% respectively.

Remarks. Bruce Mundy (in litt, July 2009) observed a pair of Owstonia at Kingman Reef ( Figs. 57 , 58 ), one with short pelvic fins and the other with long fins, alternately swimming in and out of holes on a vertical rock face. Sexually dimorphic pelvic fins occur in several other species of Owstonia , so a reasonable hypothesis is that a single species with sexually dimorphic fins was observed. Apparent color differences of the two photographed fish are an artifact of the different distances of the camera from each fish, affecting the intensity of illumination.

Figures

FIGURE 14. Arrangement and relative sizes of papillae in slight depression at tip of ascending premaxillary processes (dorsal view, anterior to right) in selected species of Owstonia: A, O. crassa, MNHN 2002 – 3720; B., O. dispar, MNHN 2002 – 3720; C, O. maccullochi, CSIRO H 5946 – 20; D, O. mundyi, USNM 427880; E, O. sarmiento, NTM S. 11782 – 001; and F, O. totomiensis, NSMT – P 77978.

FIGURE 24. Distributions of selected species of Owstonia based on specimens examined, except records of O. mundyi from Kingman Reef based solely on submersible videos, and possibly could have been misidentifications of O. hawaiiensis.

FIGURE 41. Owstonia hawaiiensis, male, Hawaiian Islands, 19 ° 52 ' 9.8 " N, 156 ° 6 ' 4 " W, Tiburon 292, depth 408.5 m, 13 April 2001. Video frame-grab, color corrected by Lonny Lundsten, image courtesy © 2001 MBARI.

FIGURE 56. Owstonia mundyi, holotype, (right side reversed), USNM 427880, 128 mm SL, Kiribati (Line Islands), Christmas Island. Photograph by Sandra J. Raredon.

FIGURE 57. Owstonia mundyi? (see discussion under Distribution), female, Kingman Reef, 338 m, submersible dive P 5 - 654. Photograph by pilot Terry Kerby, courtesy of HURL.

FIGURE 58. Owstonia mundyi? (see discussion under Distribution), male, Kingman Reef, 338 m, submersible dive P 5 - 654. Photograph by pilot Terry Kerby, courtesy of HURL.