Longfin Perchlet

description

We add the following new observations: scales with peripheral cteni; vertebrae 10 + 16, rarely 10 + 17; supraneurals 2; predorsal formula 0 / 0 / 2 / 1 + 1; dorsal pterygiophores in interneural spaces 9 – 13 1 / 1 / 1 + 1 / 1 + 1 / 1; no trisegmental pterygiophores associated with dorsal fin; terminal dorsal pterygiophore in interneural space 17; no trisegmental pterygiophores associated with anal fin; terminal anal pterygiophore in interhaemal space 5; ribs present on vertebrae 3 through 9 – 10; epineurals present on vertebrae 1 through 8 – 10; hypurals 1 and 2 represented by undifferentiated plate, other hypurals and parhypural autogenous (Figure 5 B); well-developed hypurapophysis on parhypural; epurals 3; single uroneural (posterior uroneural absent); ventral tip of cleithrum with well-developed posteroventral process; proximal tip of first anal-fin pterygiophore near distal tips of parapophyses on vertebra 10. Morphometric data are summarised in Table 24.

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. longimanus from all other congeners: dorsal rays X, 12 – 15; fourth dorsal spine longest; pectoral rays 12 – 13, all rays unbranched; lateral line incomplete, with 10 – 17 tubed scales; greatest body depth 32.3 – 39.9 % SL.

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

discussion

Plectranthias longimanus is very similar to P. nanus in coloration and most morphometric and meristic features. They are apparently unique within the genus in having hypurals 1 and 2 present as an undifferentiated plate (Figure 5 B). This potential synapomorphy has not been found in other examined Plectranthias species, where instead the two hypurals are autogenous (Figure 5 A). The two species are distinguished from each other by the following characters: number of pectoral rays (12 – 13 in P. longimanus versus 14 – 15, rarely 13 in P. nanus); number of tubed scales in the lateral line (12 – 17 versus 15 – 21); number of circumpeduncular scales (12 versus 12 – 15, usually 14); degree of development of serrations on the interopercle and subopercle (bones with 2 – 6 and 2 – 7 conspicuous serrations, respectively, versus each bone with 0 – 2 weak serrations; Figure 3); and body depth (greatest body depth 32.3 – 39.9 % SL and body depth at anal origin 27.1 – 32.0 % SL versus 29.4 – 33.3 % SL and 24.6 – 27.2 % SL, respectively). The two species also differ slightly in coloration. In particular, P. nanus is distinguished in having a pale bar on the caudal-fin base, edged posteriorly wit

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

discussion

Remarks. A small Plectranthias species (largest known specimen 29 mm SL; Heemstra & Randall 2009), P. longimanus is known in Australia from the Timor Sea, Great Barrier Reef, Coral Sea and southern Queensland (Figure 32). Elsewhere it ranges widely throughout the Indo-west Pacific, from the east African coast to Tonga (Heemstra & Randall 2009, Randall et al. 2003). In their table 1 for western Indian Ocean Plectranthias, Heemstra & Randall (2009) gave a count of 15 branched caudal-fin rays for this species. In their account for the species, however, they gave a range of 13 – 15 branched caudal rays. All specimens examined by us had 13 (7 + 6) branched caudal rays.

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