Owstonia lepiota, 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 : 60-62

Owstonia lepiota new species

( Figures 49 , 50 )

Holotype. USNM 344575, 58 mm SL, Tanzania, 6°52'12"S, 39°54''E, trawled in 200 m, R/ V Anton Bruun cruise 9, sta. 423, 20 Nov. 1964.

Diagnosis. A species of Owstonia with LL pattern type 1; about 95 oblique body scale rows in mid-lateral series (fewer than 60 oblique scale rows in other species, except O. mundyi ); nape naked and cheek scale rows 5‒6.

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Description. 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 21. Dorsal fin III, 23; anal fin II, 15; pectoral fin 19; gill rakers 12 + 20. Vertebrae: precaudal 11, caudal 18, total 29; anal-fin pterygiophores anterior to 1st haemal spine 3. Oblique longitudinal body scale rows in mid-lateral series about 95; nape naked and cheek scale rows 5‒6. Lower limb margin of preopercle 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 15/17, no inner teeth anteriorly. Teeth in lateral row of each dentary 8; symphyseal teeth 3, conical, and with 1 inner tooth anteriorly. Depressed pelvic fin extending to anal-fin origin. Caudal fin lanceolate. Caudal fin 2.7 times in SL; head 3.6 times in SL; body depth at anal-fin origin 4.6 times in SL.

Color pattern in alcohol: Dorsal fin uniformly pale; membrane connecting premaxilla and dentary with brown stripe extending to near anterior end of premaxilla, and inner membrane covering posterior part of dentary also brown (brown rather than black coloration probably due to preservation history). Life coloration unknown.

Proportions of 58 mm SL holotype as percentages of SL: predorsal length 28.1; preanal length 57.3; dorsal-fin base 61.6; anal-fin base 39.1; pelvic-fin length 24.3; caudal-fin length 37.0; body depth at anal-fin origin 21.9; head length 27.8; upper jaw length 13.7; upper jaw depth 4.8; orbit diameter 10.4. As percentages of head length: upper jaw length 49.1; orbit diameter 37.5.

Comparisons. The allopatric O. mundyi is superficially similar to O. lepiota in having a high number of oblique body scale rows in mid-lateral series, 97‒108 (vs. 95) and a naked nape but differs in lacking cheek scales (vs. 5–6 cheek scale rows) and having anal-fin rays I, 15–16 (vs. II, 15).

Etymology. From the Greek lepis (scale) and iota (anything small) and, in reference to the relatively small body scales. The name is treated as a noun in apposition.

Distribution. ( Fig. 27 ) Known only from off Tanzania where trawled in 200 m.

Remarks. Although the holotype is relatively large, it has a distinctly enlarged posttemporal and preopercle ( Fig. 50 ). These features have otherwise been observed only in Owstonia larvae, suggesting that this individual remained in the water column for an extended period of time, presumably due to its failure to find or detect suitable benthic habitat prior to settlement.

Figures

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

FIGURE 49. Owstonia lepiota, holotype, USNM 344575, 57.6 mm SL, Tanzania. Photograph by Sandra J. Raredon.

FIGURE 50. Owstonia lepiota, holotype, close-up of head showing enlarged posttemporal and preopercle.