Plectranthias Bleeker 1873

Plectranthias sp. 1

Figure 3; Table 3

A single specimen of a possibly new species of Plectranthias was collected and photographed during the 2015 survey (Figure 3). Morphometric values for the specimen are provided in Table 3. It closely resembles P. sagamiensis (Katayama, 1964) from southern Japan in coloration and in having the following combination of characters: segmented dorsal-fin rays 15; pectoral fin with 14 mostly unbranched rays (8th ray on left side branched, 7th and 8th rays on right side branched); lateral line complete with 29–30 tubed scales; lower part of preopercle with two enlarged antrorse spines; no scales on maxilla; and predorsal scales extending anteriorly to middle of interorbital area (at about vertical through mid-pupil). However, a segmented dorsal-ray count of 15 is unusual for P. sagamiensis, with 16 the more usual count (Randall, 1980). The specimen also differs from Randall’s (1980) diagnosis of P. sagamiensis in having fewer rows of cheek scales (5 versus 6).

The specimen also closely resembles an undescribed species from the Northwest Shelf of Australia in coloration and most meristic details. However, the Northwest Shelf species has more extensive coverage of predorsal scales (extending anteriorly to at least the vertical through the anterior edge of the pupil, sometimes to the posterior nostrils versus to the vertical through the middle of the pupil), as well differing in some morphometric details (e.g. greatest body depth 32.4–39.3 versus 44.4 % SL; head length 42.6–45.7 versus 50.2 % SL; first segmented dorsal-fin ray 14.4–16.6 versus 19.3 % SL). Although it is likely this specimen represents a new species, we refrain from describing it until more specimens become available, and until proper comparisons can be made with P. sagamiensis.

Material examined: SAIAB 203726, 45.0 mm SL, off Tanintharyi coast, Myanmar, Andaman Sea, Indian Ocean (13°3.21’ N, 96°41.62’ E) 121–129 m, R/ V Dr. Fridtjof Nansen, stn 123, bottom trawl, 21 May 2015, collected by P. N. Psomadakis..