Owstonia hawaiiensis, 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 : 52-54

Owstonia hawaiiensis new species

( Figures 40 , 41 )

Owstonia sp. Grigg, et al., 1987:387 (Cross Seamount, photographed in 300–600 m); Chave and Mundy, 1994:389 (Hawaiian records, observations in 349–420 m).

Sphenanthias sp Mundy, 2005:418 (larvae reported from Cross and Lōʻihi seamounts to Oahu, Hawaii).

Holotype. (Only known specimen) BPBM 29660, 124 mm SL, female, Hawaiian Islands , Mauno Kea Ledge, 19°54'N, 154°57.7' W, 366 m (1200 ft), collected with suction device by E. H. Chave and B. Bartko (pilot of submersible Makalii) , HURL dive 218, 9 Feb. 1984.

Other material. (See also Remarks) Six larvae 10.9‒17.2 mm SL, all from off Oahu , Hawaii, 13 km off leeward side, Jul. 1978, T. A. Clarke: LACM 45959‒9 (1, 12.6) ; LACM 45962‒11 (1, 10.9); LACM 45965‒7 (1, 14.6); LACM 45966‒10 (1, 17.2); LACM 45967‒10 (1, 13.2); LACM 45990‒10 (1, 13.4).

Diagnosis. A species of Owstonia with LL pattern type 1; lower limb margin of preopercle without spines; dorsal fin III, 19; no dark premaxillary stripe; adults with 34–35 teeth in outer row of each premaxilla; papillae in slight depression behind tip of ascending process of premaxillae with a cluster of about 5 minute papillae present between the posterior pair of relatively large papillae.

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 rays 19‒20. Dorsal fin III, 19; anal fin I, 13; pectoral fin 19; gill rakers 15 + 28 = 43. Vertebrae: precaudal 11, caudal 17, total 28; anal-fin pterygiophores anterior to 1st haemal spine 3. Oblique body scale rows in mid-lateral series about 37 or 38; nape scaly and cheek scale rows about 4, left side only. Lower limb margin of preopercle without spines. Papillae in slight depression behind tip of premaxillary ascending processes 4, relatively large and arranged in 2 almost equally spaced pairs, with a cluster of about 5 minute papillae between the posterior pair of papillae. Teeth in outer row of each premaxilla 34/35, the anterior ones larger and slightly hooked; 2‒3 inner teeth anteriorly. Teeth in lateral row of each dentary 15, the anterior 6 or 7 moderately slender and slightly hooked ( Fig. 10 D); symphyseal teeth 3‒4, all conical, and with 3 similar-sized inner teeth anteriorly. Pelvic fin sexually dimorphic, depressed pelvic fin extending to1st anal-fin soft ray in female holotype, and an individual observed in video recordings off Hawai'i Island ( Fig. 41 ) has very long pelvic fins extending to near rear of anal fin. Caudal fin lanceolate. Holotype with caudal fin 2.4 times in SL; head 3.2 times in SL; body depth at anal-fin origin 3.6 times in SL.

Color pattern in alcohol: Adults with dorsal fin pale, membrane connecting maxilla and premaxilla, and inner membrane covering posterior part of dentary unpigmented. In life, head and body red, paler below, distal margin of dorsal fin and elongate anal-fin soft ray of males white. Caudal and anal fins pale with narrow red margins, and dorsal fin with narrow submarginal red stripe, wider posteriorly. Based on submersible videos, fish from Kingman Reef, presumed to be Owstonia mundyi , have virtually identical life coloration.

Proportions of 124 mm SL female holotype as percentages of SL: predorsal length 29.6; preanal length 58.8; dorsal-fin base 61.4; anal-fin base 30.9; pelvic-fin length 32.4; caudal-fin length 41.9; body depth at anal-fin origin 28.1; head length 31.1; upper jaw length 16.1; upper jaw depth 7.0; orbit diameter 13.7. As percentages of head length: upper jaw length 51.8; orbit diameter 44.0.

Comparisons. Owstonia hawaiiensis is very similar to the allopatric O. ignota but differs in several subtle characters (refer to Remarks in following species account) including relatively smaller and only slightly hooked mid-lateral dentary teeth ( Fig. 10 D), and papillae in slight depression behind tip of ascending process of premaxillae with a cluster of about 5 minute papillae present between the posterior pair of relatively large papillae (vs. no cluster of minute papillae present in O. ignota ). The only other congener from the central Pacific Ocean known from adults is the very distinctive O. mundyi , which differs from O. hawaiiensis in having nape and cheeks without scales (vs. nape and cheeks scaly), oblique body scale rows in mid-lateral series 97–108 (vs. 37‒38) and a black premaxillary stripe (vs. premaxillary stripe absent). Owstonia grammodon also agrees with O. hawaiiensis in having most of these characters, including a low number of dorsal- and anal-fin soft rays and adults with relatively high numbers (33–39) of teeth in the outer row of each premaxilla, but differs in having a prominent black premaxillary stripe (vs. premaxillary stripe absent in O. hawaiiensis ).

Etymology. The specific epithet is a combination of Hawaii, the type locality where it is presumably endemic, and the Latin suffix ensis (meaning belonging to).

Distribution. ( Fig. 24 ) Known only from the Hawaiian Archipelago. In addition to the holotype, fish we assume to be O. hawaiiensis have been observed from submersibles in 342–420 m in Hawaiian waters ( Chave and Mundy, 1994), in 300–600 m at Cross Seamount, 18°40'N, 158°17'W ( Grigg et al., 1987), and at 19°53'N, 156°6'W in 408 m (see Fig. 41 ).

Remarks. Six larvae from Oahu (see above) have a combination of dorsal- and anal-fin soft rays and caudal vertebral counts that match only those of O. hawaiiensis , O. ignota or Owstonia sp. 2 from Tarasoc seamounts, but the strong modal difference (4 vs. 3) in numbers of pterygiophores anterior to 1st haemal spine does not agree with this triad of species or with O. mundyi (see Table 5).We tentatively identify these larvae as O. hawaiiensis but do not designate them as paratypes. The very distinctive O. mundyi , the only other described congener known from the eastern part of the central Pacific Ocean, differs from O. hawaiiensis , the Hawaiian larvae and Owstonia sp. 2 in having no overlap in number of dorsal- and anal-fin soft rays ( Table 4).

Figures

FIGURE 10. Premaxilla and dentary (mostly right side reversed) to show dentition in selected species of Owstonia. A, O. contodon, USNM 438013, 162 mm SL; B, O. fallax, CSIRO H. 763 ‒ 06, holotype, 110 mm SL; C, O. grammodon, USNM 149321, 127 mm SL; D, O. hawaiiensis, BPBM 29600, holotype, 124 mm SL; E, O. ignota, USNM 344400, holotype, 118 mm SL; F, O. japonica, ANSP 151948, 136 mm SL.

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 40. Owstonia hawaiiensis, holotype, BPBM 29660, 124 mm SL, female, Hawaiian Islands. Photograph by John E. Randall.

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.