Owstonia rhamma, 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 : 77-79

publication ID

https://doi.org/ 10.11646/zootaxa.4187.1.1

publication LSID

lsid:zoobank.org:pub:4F14F9CF-6D55-4ECF-B034-C446B7A1AAC0

DOI

https://doi.org/10.5281/zenodo.5245018

persistent identifier

https://treatment.plazi.org/id/B9494D69-BE79-AB3F-0ACB-741BFF4BF998

treatment provided by

Plazi

scientific name

Owstonia rhamma
status

sp. nov.

Owstonia rhamma new species

( Figures 68 View FIGURE 68 , 69 View FIGURE 69 )

Holotype. MNHN 1995–0005, 102 mm SL, Vanuatu, 20°19'58.8"S, 169°49'1.2"E, MUSORSTOM 8, sta. 963, beam trawl in 400–440 m, 20 Sep. 1994. GoogleMaps

Other material. MNHN 2013–0354 About MNHN , (1, 50), Vanuatu, W. of Malo Island, 15°41'16.8"S, 167°2'34.8"E, 321– 336 m, Exped. Santo 6, sta. at18, 21 Sep. 2006 GoogleMaps .

Diagnosis. A species of Owstonia with LL pattern type 3; Dorsal fin III, 21; anal fin I, 14; nape scaly and cheek scale rows 2-3; dentary with 4 or 5 mid-lateral teeth noticeably enlarged and hooked backwards ( Fig. 69 View FIGURE 69 ).

Description. (Characters of the 50 mm SL specimen that are observable are given in parentheses when they differ from the holotype; also see below Remarks.) A species of Owstonia with LL pattern type 3, consisting of a lateral line that does not contact posttemporal sensory canal near anterodorsal margin of gill opening, but instead continues posteriorly just below dorsal-fin base to soft rays 19/20 (16) and anteriorly for about 5 scale rows beyond dorsal-fin origin (on left side) and on right side slightly beyond dorsal-fin origin but too many scales missing on nape to determine if the lateral line makes a complete loop across nape (nape loop definitely incomplete in the small specimen). Dorsal fin III, 21; anal fin I, 14; pectoral fin 19 (21/23); gill rakers 16 + 29 (15 + 30) (left gill arch of holotype missing). 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 50; nape scaly and cheek scale rows 2 or 3. Lower limb margin of preopercle with 5−6 very small blunt spines which could easily be overlooked ( Fig. 8 View FIGURE 8 F). Papillae in slight depression behind tip of premaxillary ascending processes 4, arranged in 2 approximately equally spaced pairs. Teeth in outer row of each premaxilla 16/22 (14); 2 (0) inner teeth anteriorly. Teeth in lateral row of each dentary 11/12 (11), 4 or 5 mid-lateral teeth noticeably enlarged and hooked backwards ( Fig. 69 View FIGURE 69 ); symphyseal teeth 4 (3) moderately large, conical, and with 2/1 (1) inner teeth anteriorly. Depressed pelvic fin extending to base of anal-fin soft ray 4 (2). Caudal fin lanceolate. Holotype with caudal fin 2.3 times in SL; head 3.0 times in SL; body depth at anal-fin origin 3.5 times in SL.

Color pattern in alcohol: Holotype with dorsal fin uniformly pale (small specimen with traces of melanophores distally in spinous dorsal fin); membrane connecting maxilla and premaxilla with prominent black stripe extending to near end premaxilla, but inner membrane covering posterior part of dentary pale with no trace of melanophores. Life coloration unknown.

Proportions of 102 mm SL holotype, with those of the 50 mm specimen (in parentheses), as percentages of SL: predorsal length 27.2 (27.9); preanal length 56.7 (55); dorsal-fin base 63.5 (63.6); anal-fin base 35.3 (32.9); pelvicfin length 27.9 (31.3); caudal-fin length 44.1 (27.6); body depth at anal-fin origin 28.7 (29.3); head length 33.0 (33.8); upper jaw length 16.3 (18.7); upper jaw depth 7.3 (8.6); orbit diameter 13.5 (16.4). As percentages of head length: upper jaw length 49.3 (55.4); orbit diameter 41.0 (48.5).

Comparisons. Owstonia maccullochi and O. doryptera are the only other species with most of the diagnostic characters of O. rhamma but differ (characters of O. rhamma given in parentheses) as follows: O. maccullochi typically has more dorsal- and anal-fin soft rays 22 and 15 respectively (vs. 21 and 14, see Table 4) more pectoral fin rays, typically 20 or 21 (vs. 19), and more cheek scale rows 5–6 (vs. 2–3). Owstonia doryptera has a lateral line with a complete nape loop (vs. lateral line apparently not united as a complete loop across nape), more cheek scale rows, 5–6 (vs. 2 or 3) and no enlarged lateral dentary canines (vs. several lateral canines noticeably enlarged, Fig. 69 View FIGURE 69 ).

Etymology. From the Greek rhamma (seam or suture) in allusion to the lateral line ( Fig. 68 View FIGURE 68 ), which is reminiscent of a surgeon’s suture. The name is treated as a noun in apposition.

Distribution. ( Fig. 22 View FIGURE 22 ) Known only from the Vanuatu type locality and Malo Island vicinity, where trawled in 400–440 and 321– 336 m.

Remarks. The small individual from near Malo Island is tentatively identified as Owstonia rhamma based, in part, on the Vanuatu locality and similarity of its dentition to that of the holotype, but in the absence of body and cheek row scale counts we cannot make an unequivocal identification. The relatively larger orbit diameter 13.5% SL (vs. 16.4%) and traces of melanophores on the spinous dorsal fin of Malo Island specimen are presumably size related.

MNHN

Museum National d'Histoire Naturelle

Kingdom

Animalia

Phylum

Chordata

Class

Actinopterygii

Order

Perciformes

Family

Cepolidae

Genus

Owstonia

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