Plectranthias alleni Randall

Gill, Anthony C., Pogonoski, John J., Moore, Glenn I. & Johnson, Jeffrey W., 2021, Review of Australian species of Plectranthias Bleeker and Selenanthias Tanaka (Teleostei: Serranidae: Anthiadinae), with descriptions of four new species, Zootaxa 4918 (1), pp. 1-116 : 34-38

Plectranthias alleni Randall

Figures 2 , 8–9 , Tables 1–17, 19

Common name: Allen’s Perchlet

Plectranthias alleni Randall 1980: 113 , fig.1, table 4 (type locality, off SW Western Australia).— Allen 1985: 2508 (checklist, Western Australia).— Paxton et al. 1989: 506 (checklist).— Hutchins 2001: 30 (checklist).— Allen et al. 2006: 989 (checklist).— Anderson 2018: 25 (checklist).— Parenti & Randall 2020: 23 (checklist).

Diagnosis. The following combination of characters distinguishes P. alleni from congeners: segmented dorsal rays 14 (rarely 13); pectoral rays 16 (rarely 15 or 17), middle rays branched; lateral line complete, with 31–36 tubed scales; no antrorse spines on ventral margin of preopercle; no scales on maxilla. The species is also relatively distinctive in having a short dark stripe in front of the eye, a faint dusky stripe from behind eye across upper side of body, and a faint small dusky spot at midbase of caudal fin (stripes and spot better developed in small specimens).

Remarks. A moderate-sized Plectranthias (largest examined specimen, 71.0 mm SL), Randall (1980) described P. alleni on the basis of the holotype and 35 paratypes trawled in 90–192 m off southwest Western Australia (between 29 and 33° S). In spite of the large number of specimens, live coloration was not recorded. We located two photographs in CSIRO; the first specimen ( Figure 8 ) collected from west of Geraldton, WA, was taken in a beam trawl from 389-407 m depth, while the second specimen was collected from northwest of Perth in a sled in 205- 210 m. Both specimens agree well with the original description of P. alleni and with the diagnosis above. We also examined additional non-type material from west of Garden Island, west of Rottnest Island, west of Mandurah, southwest of Cape Naturaliste, and west of Cervantes (see below).

Paratypes in WAM P.23325-001 (as they are now accessioned) were originally 10 specimens with registration numbers between P.23325 and P.23330, but were lumped together by Randall (1980) and incorrectly referred to as WAM P.23325–30 (see Moore et al. 2008). Furthermore, we determined one of these paratypes is actually a misidentified 32.5 mm SL specimen of Lepidoperca occidentalis Whitley, 1951 . The L. occidentalis specimen does not appear to have contributed to Randall’s description of P. alleni . We have separated the specimen from the remaining paratypes and allocated it the number WAM P.23330-001; the remaining nine paratypes remain as WAM P.23325- 001.

The original description of P. alleni lacks information on several characters that may help clarify relationships of the species. We therefore provide the following new information: scales with basal cteni; 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 or 1/1/1/1+1/1+1; 0–2 trisegmental pterygiophores associated with dorsal fin; terminal dorsal pterygiophore in interneural space 17–18; 0–3 trisegmental pterygiophores in anal fin; terminal anal pterygiophore in interhaemal space 4–5; ribs present on vertebrae 3 through 10; epineurals present on vertebrae 1 through 12–14; 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. Western Australia, Australia. AMS I.20125-001, 48.4 mm SL (paratype), off Rottnest Island , 165–166 m, dredge, R. George , FV Bluefin, 15 Aug 1962; CSIRO H 6365-14 , 45.3 mm SL, west of Rottnest Island , 31°59.54′S, 115°10.98′E to 32°00.12′S, 115°10.68′E, 478–508 m, beam trawl, CSIRO, FRV Southern Surveyor , 29 Nov 2005 ( SS1005 /68); CSIRO H 6371-10 , 71.0 mm SL, west of Geraldton , 28°59.40′S, 113°45.90′E to 28°59.80′S, 113°46.14′E, 389–407 m, beam trawl, FRV Southern Surveyor , 03 Dec 2005 ( SS1005 /90); CSIRO H 6476-02 , 67 mm SL (radiograph only), northwest of Perth , 31°37.45′S, 115°00.24′E to 31°37.71′S, 115°00.18′E, 205–210 m, Sherman sled, FRV Southern Surveyor , 19 Nov 2005 ( SS1005 /11); WAM P.23309-001, 55.0 mm SL (paratype, radiograph only), west of Lancelin , HMAS Diamantinia , 23 Mar 1972; WAM P.23334-001, 61.7 mm SL (paratype, radiograph only), west of Rottnest Island , 32°00′S, 115°15′E, 146–150 m, HMAS Diamantinia , 23 Mar 1972; WAM P.23325-001, 9: 29.3–58.2 mm SL (paratypes), west of Green Head , 29°59′S, 118°25′E, 146 m, dredge, HMAS Diamantina , 22 Mar 1972; WAM P.23331-001, 47.2 mm SL, southwest of Cape Naturaliste , HMAS Diamantina , 16 Mar 1972; WAM P.25625-001, 52.0 mm SL (holotype, radiograph only), off southwest Western Australia, 29°09′S, 113°55′E, 103 m, dredge, RV Sprightly , 19 Feb 1976; WAM P.29069-001, 46.4 mm SL, west of Mandurah , 32°30′S, 115°00′E, HMAS Diamantina , Nov 1970; WAM P.29070-001, 58.2 mm SL, west of Garden Island , HMAS Diamantina , 18 Mar 1972; WAM P.29071-001, 1: 43.2 mm SL, west of Cervantes , 30°33′S, 114°32′E, HMAS Diamantina , 18 Mar 1972.

Figures

FIGURE 2. Plectranthias alleni, WAM P.29069-001, 46.4 mm SL, view of right side of head (reversed) showing bone serrations. Specimen stained with Cyanine Blue 5R (Saruwatari et al. 1997). Abbreviations: IO1, infraorbital 1; IOP, interopercle; LLS1–3, anterior three lateral-line scales; PTT, posttemporal; POP, preopercle; SOP, subopercle. Arrows point to serrations on opercle. Scale bar = 5 mm. Photo by A.C. Gill.

FIGURE 8. Plectranthias alleni, CSIRO H 6371-10, 71.0 mm SL, west of Geraldton, Western Australia. Specimen frozen for 8 years prior to photography. Photo by C. Devine, CSIRO.

FIGURE 9. Distribution records for Plectranthias alleni (closed circles), P. grahami (open circle) and P. robertsi (triangles).