Plectranthias ferrugineus

description

Description. Dorsal rays X, 14 (X, 14 – 16), all (all or all but first) segmented rays branched; anal rays III, 7, all segmented rays branched; pectoral rays 13 / 13 (13 – 14), all rays unbranched; pelvic fin I, 5, all segmented rays branched; upper procurrent caudal-fin rays 6 (5 – 6); lower procurrent caudal-fin rays 5 (5 – 6); principal caudal-fin rays 9 + 8; branched caudal fin rays 7 + 7 (7 + 6 – 7); total caudal-fin rays 28 (27 – 29); lateral line complete with 29 /? (27 – 30) scales; scales above lateral line to origin of dorsal fin 3 / 3 (2 – 3); scales above lateral line to base of fifth dorsal spine 2 / 2 (1 – 2); scales below lateral line to origin of anal fin 11 / 11 (10 – 12); diagonal rows of scales on cheek 5 (5 – 7); predorsal scales 19 (15 – 22); circumpeduncular scales 16 (14 – 16); gill rakers 6 + 12 (4 – 7 + 11 – 14 = 16 – 20), the upper 4 – 6 and lower 2 – 6 rudiments; pseudobranchial filaments 8 (8 – 14); branchiostegal rays 7. Vertebrae 10 + 16; supraneurals 3; predorsal formula 0 / 0 + 0 / 2 / 1 + 1; dorsal pterygiophores in interneural spaces 9 – 13 1 / 1 / 1 + 1 / 1 + 1 / 1 (1 / 1 / 1 + 1 / 1 + 1 / 1, 1 / 1 / 1 + 1 / 1 / 1 + 1 or 1 / 1 / 1 + 1 / 1 + 1 / 1

Review of Australian species of Plectranthias Bleeker and Selenanthias Tanaka (Teleostei: Serranidae: Anthiadinae), with descriptions of four new species

diagnosis

Diagnosis. The following combination of characters distinguishes P. ferrugineus from congeners: dorsal fin with 14 – 16, modally 15 segmented dorsal rays; fourth dorsal spine longest; pectoral fin with 13 – 14 unbranched rays; lateral line complete with 27 – 30 tubed scales; lower part of preopercle with two enlarged antrorse spines; predorsal scales extending anteriorly to anterior part of interorbital area.

Review of Australian species of Plectranthias Bleeker and Selenanthias Tanaka (Teleostei: Serranidae: Anthiadinae), with descriptions of four new species

discussion

Comparisons. The combination of 14 – 16 segmented dorsal-fin rays, fourth dorsal spine longest, pectoral fin with 13 – 14 unbranched rays, lateral line complete with 27 – 30 tubed scales, and lower part of preopercle with 2 enlarged antrorse spines separates P. ferrugineus from all other described Plectranthias species except P. ryukyuensis Wada, Susuki, Senou & Motomura, 2020 and P. sagamiensis (Katayama, 1964). The former species was described from four specimens (41.2 – 61.6 mm SL) from the Okinawa Islands, Ryukyu Islands, Japan. Our comparisons with that species are based on data provided by Wada et al., as well as our original observations on a 70.5 mm SL specimen from Okinawa, obtained through the Singapore aquarium trade (AMS I. 49477 - 001; Figure 19). Our comparisons with P. sagamiensis are based on Wada et al. ’ s data from available type specimens from Sagami Bay, Honshu (including the holotype), and additional non-type specimens from various localities in Japan (total 22 specimens, 35.5 – 57.3 mm SL). Plectranthias ferrugineus differs from P. ryukyuensis in having longer third and fourth dorsalfin spines (16.4 – 21.3 and 19.0 – 24.1 % SL, respectively, versus 14.4 – 16.

Review of Australian species of Plectranthias Bleeker and Selenanthias Tanaka (Teleostei: Serranidae: Anthiadinae), with descriptions of four new species

distribution

Habitat and distribution. This species is known only from beam trawls and sled captures on the North West Shelf, off Western Australia, eastwards to the Arafura Sea, Northern Territory, at a very narrow depth range of 95 to 109 m (Figure 18). Video camera footage from the type locality showed the habitat to consist of low relief silty sand / mud with dense patches of crinoids and erect, cup-shaped sponges.

Review of Australian species of Plectranthias Bleeker and Selenanthias Tanaka (Teleostei: Serranidae: Anthiadinae), with descriptions of four new species