Plectranthias japonicus (Steindachner)

Figures 1, 7, 25; Tables 1–16, 19

Common name: Japanese Perchlet

Paracirrhites japonicus Steindachner in Steindachner & Döderlein 1883b: 25 (type locality: Japan).

Plectranthias japonicus .— Sainsbury et al. 1985: 337 (diagnosis, colour photo, off Northern Territory).— Allen 1985: 2508 (checklist, Western Australia).— Paxton et al. 1989: 506 (checklist).— Hutchins 2001: 30 (checklist).— Allen et al. 2006: 990 (checklist).— Larson et al. 2013: 102 (checklist).— Anderson 2018: 29 (checklist).— Parenti & Randall 2020: 26 (checklist).

Sayonara satsumae Jordan & Seale 1906: 145, fig. 3 (type locality: Yamakawa, Japan).— Paxton et al. 1989: 507 (checklist, North West Shelf).

Sayonara mitsukurii Smith & Pope 1906: 469, fig. 3 (type locality: Kagoshima, Japan).

Diagnosis. The following combination of characters distinguishes P. japonicus from congeners: segmented dorsal rays 14–16, usually 15; fourth or fifth dorsal spine longest; pectoral rays 15–17, usually 16; lateral line complete, consisting of 30–35 tubed scales; posterior preopercle with 17–40 serrations, which continue around corner of bone to posteroventral edge; no antrorse serrations on ventral edge of preopercle; margins of subopercle and interopercle serrate.

Remarks. A relatively large Plectranthias species (largest specimen 129 mm SL), P. japonicus is known in Australia from the North West Shelf and Arafura Sea (Figure 7). Outside of Australia, it is known from southern Japan, Taiwan, and southern Indonesia (Randall 1980; Gloerfelt-Tarp & Kailola 1984; Lee 1990).

We add the following new observations: scales with basal cteni; vertebrae 10+16; supraneurals 2; predorsal formula 0/0/2/1+1; dorsal pterygiophores in interneural spaces 9–13 1/1/1+1/1+1/1+1 or 1/1/1+1+1/1/1+1; 6–13 trisegmental pterygiophores associated with dorsal fin; terminal dorsal pterygiophore in interneural space 17–18; 4–6 trisegmental pterygiophores associated with anal fin; terminal anal pterygiophore in interhaemal space 4–5; ribs present on vertebrae 3 through 10; epineurals present on vertebrae 1 through 9–11; parhypural and hypurals autogenous; 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 19.

Material examined. Australia. AMS I.21835-020, 81.3 mm SL, Northern Territory, Arafura Sea, 09°21′S, 132°12′E, 156–164 m, otter trawl, FRV Soela, 15 Nov 1980 (field number SO7/80/36); CSIRO H 2548-02, 101 mm SL, CSIRO H 2548-10, 3: 56.9–129 mm SL, Western Australia, northwest of North West Cape, 21°44.7′S, 113°52.3′E to 21°44.5′S, 113°52.5′E, 290–320 m, Engel trawl, P. Last, FRV Southern Surveyor, 24 Jan 1991 (field station number SS0191/8); NTM S.13147-005, 99.3 mm SL, Northern Territory, Arafura Sea, 9°47′S, 130°26′E, 255 m, D. Evans, 9 Dec 1990; NTM S.13577-005, 71.4 mm SL, Northern Territory, Arafura Sea, 9°5.1′S, 133°39.7′E, 165–176 m, R.S. Williams, 20 Oct 1992. Japan. CAS-SU 9259, 123 mm SL (holotype of Sayonara satsumae Jordan & Seale, 1906; radiograph only), Kagoshima Prefecture, near Kagoshima, Yamagawa, K. Mitsukuri; USNM 55617, 70 mm SL (holotype of Sayonara mitsukurii Smith & Pope 1906; radiograph only), Kagoshima, H.M. Smith, 16 Jun 1903 .