Plectranthias robertsi Randall & Hoese

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 : 102-103

Plectranthias robertsi Randall & Hoese

Figures 9 , 42 ; Tables 1–16, 19

Common name: Filamentous Perchlet

Plectranthias robertsi Randall & Hoese 1995: 328 , fig. 2, table 1 (type locality, east of Hinchinbrook Island, Queensland).— Allen et al. 2006: 991 (checklist).— Last et al. 2014: 217 (list).— Anderson 2018: 32 (checklist). — Parenti & Randall 2020: 29 (checklist).

Diagnosis. The following combination of characters distinguishes P. robertsi from congeners: segmented dorsal rays 15; fourth or fifth dorsal-fin spine longest; pectoral rays 15–16, usually 16; lateral line complete, with 30–35 tubed scales; circumpeduncular scales 15–16; outer margin of preopercle with 26–52 serrae, and no enlarged antrorse serrations ventrally; scales present on maxilla; scales present on anguloarticular, none on dentary; gill rakers 5–8+13–16, usually 6–7+13–14. The species is also distinctive in having the posterior branch of the second segmented pelvic-fin ray filamentous, and a generally pale preserved coloration with dusky spots on the anterior few lateral-line scales.

Remarks. Randall & Hoese (1995) described P. robertsi on the basis of the holotype and 32 paratypes from various localities off the Queensland coast (ranging from about 17° to 23°S). Although Randall & Hoese described freshly dead coloration for the species based on a colour slide of one of their specimens, they did not publish the photo. We located three specimens from east of Rockingham Bay, two of which were photographed when fresh. We reproduce one of the photos here ( Figure 42 ). Additional type and non-type specimens were examined from throughout the range of the species ( Figure 9 ).

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 or 1/1/1+1/1+1/1+1; 8–9 trisegmental pterygiophores associated with dorsal fin; terminal dorsal pterygiophore in interneural space 17; 4–6 trisegmental pterygiophores associated with anal fin; terminal anal pterygiophore in interhaemal space 4–5; ribs present on vertebrae 3 through 9–10; epineurals present on vertebrae 1 through 9–10; 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. Queensland, Australia. AMS I.20968-003, 87.1 mm SL (holotype), east of Hinchinbrook Island , 18°03′S, 147°10′E, 357 m, prawn trawl, Australian Museum and Australian Institute of Marine Science team, 27 Feb 1979 ; AMS I.37598-006, 73.3 mm SL, east of Swains Reef , 21°48.44′S, 152°59.94′E to 22°00.58′S , 153°06.88′E, 201 m, trap, J. Lowry & K. Dempsey, FV Capricorn 1, 14 Sep 1995; AMS I.38088-013, 62.7 mm SL, east of Swains Reef , 21°50.99′S, 153°01.40′E to 21°59.4′S, 153°06.6′E, 199 m, bottom trawl, J.K. Lowry & K. Dempsey aboard FV Seadar Bay , 11 Sep 1995 ; CSIRO H 682-1 , 78.8 mm SL (paratype), east of Dunk Island , 17°59.9′S, 147°02.9′E to 17°57.6′S, 147°00.3′E, 250–252 m, lobster trawl, RV Soela Station SO06-85/44, J. Stevens, 29 Nov 1985 ; CSIRO H 691-1 , 81.0 mm SL (paratype), east of Dunk Island , 17°59.1′S, 147°09.6′E to 17°55.8′S, 147°06.9′E, 400–402 m, lobster trawl, RV Soela Station SO06-85/47, J. Stevens, 29 Nov 1985 ; CSIRO H 3645-13 , 97.8 mm SL, CSIRO H 3645-14 , 76.6 mm SL, CSIRO H 3645-15 , 97.2 mm SL, east of Rockingham Bay , 18°01.5′S, 147°06.2′E to 18°05.9′S, 147°08.9′E, 239–266 m, demersal trawl, G. Yearsley, FRV Southern Surveyor , 30 Nov 1993 (field station number SS0793/ T4 ) ; CSIRO H 3644-14, 112.6 mm SL, east of Rockingham Bay , 17°56.4′S, 147°02.7′E to 17°59.7′S, 147°07.5′E, 303–320 m, demersal trawl, G. Yearsley, FRV Southern Surveyor , 30 Nov 1993 (field station number SS0793/ T3 ) ; NMV A 4504 , 2 : 73.3–89.7 mm SL, 95 km east of Dunk Island , 18°00′S, 147°02′E to 17°57′S, 146°59′E, 220 m, Engel trawl, RV Soela , 8 Jan 1986 .

Additional specimens identified for distribution information. Queensland, Australia . CSIRO H 719-12, 125 mm SL, CSIRO H 719-13, 105 mm SL, CSIRO H 719-14, 127 mm SL, CSIRO H 719-15 , 127 mmm SL , CSIRO H 719-16, 122 mm SL, CSIRO H 719-17, 125 mm SL (paratypes), Capricorn Channel , southeast of Swain Reefs, 22°56.12′S, 153°00.13′E to 22°53.3′S, 152°59.3′E, 325–338 m, mud bottom, lobster trawl, RV Soela Station SO06-85/12, 18 Nov 1985 ; CSIRO H 690-01 , 3 : 70–89 mm SL (paratypes), west of Saumarez Reef , 21°33.4′S, 152°58.2′E to 21°31.1′S, 152°58.4′E, 239–247 m, RV Soela Station SO06-85/19, 28 Nov 1985 ; QM I.20024, 78.4 mm (paratype), Capricorn Channel , 22°51.7′S, 152°45.7′E, 261 m, trawl, RV Craigmin, 3 Oct 1980 ; QM I.24075, 2: 29–92 mm SL, east of Tully , Coral Sea, 17°57.06′S, 147°02.5′E, trawl 287–300m, Cidaris , 16 May1986 ; QM I.24145, 78 mm SL, east of Tully , Coral Sea, 17°55.38′S, 147°00′E, trawl 295–309m, Cidaris , 16 May 1986 ; QM I.24430, 30: 47–113 mm SL, QM I.24527, 3: 74–91 mm SL, QM I.24528, 15: 53–114 mm SL, QM I.24589, 2: 84–87 mm SL, Coral Sea , east of Innisfail, 17°38′S, 146°50′E, trawl 298–301m, Cidaris , 15 May 1986 .

Figures

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

FIGURE 42. Plectranthias robertsi, CSIRO H 3645-13, 97.8 mm SL, freshly dead, east of Rockingham Bay, Queensland. Photo by T. Carter, CSIRO.