Plectranthias grahami, Gill & Pogonoski & Moore & Johnson, 2021

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 : 63-65

Plectranthias grahami n. sp.

Figures 9 , 22 ; Tables 1–16, 18

Common name: Graham’s Perchlet

Holotype. AMS I.18855-003, 122.5 mm SL, Australia, Tasman Sea, New South Wales, east of Bulli , 34°18′S, 151°26′E, 457–485 m, demersal prawn trawl, K. Graham, FRV Kapala , 20 Aug 1975 (field number K 75-05-06).

Diagnosis. The following combination of characters distinguishes P. grahami from all congeners: dorsal rays X,15; pectoral rays 18; lateral-line scales 41–42; and gill rakers 6+13.

Description. Dorsal rays X,15, all segmented rays branched; anal rays III,7, all segmented rays branched; pectoral rays 18/18, upper ray unbranched; pelvic fin I,5, all segmented rays branched; upper procurrent caudal-fin rays 8; lower procurrent caudal-fin rays 7; principal caudal-fin rays 9+8; branched caudal fin rays 8+7; total caudal-fin rays 32; lateral line complete with 41/42 scales; scales above lateral line to origin of dorsal fin 5/5; scales above lateral line to base of fifth dorsal spine 3/3; scales below lateral line to origin of anal fin 15/16; diagonal rows of scales on cheek 9; predorsal scales 42, extending to upper lip; circumpeduncular scales 18; gill rakers 6+13, the upper 4 and lower 2 rudiments; pseudobranchial filaments 19; branchiostegal rays 7.

Vertebrae 10+17; supraneurals 3; predorsal formula 0/0+0/2/1+1; dorsal pterygiophores in interneural spaces 9–13 1/1/1/1+1/1+1; 0 trisegmental pterygiophores associated with dorsal fin; terminal dorsal pterygiophore in interneural space 18; 2 trisegmental pterygiophores associated with anal fin; terminal anal pterygiophore in interhaemal space 5; ribs present on vertebrae 3 through 10; epineurals present on vertebrae 1 through 12; 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 vertebra 10 ( Figure 22B ).

Dorsal-fin spines with short fleshy tabs on their distal tips; fourth dorsal spine longest; dorsal fin incised before first segmented-fin ray, the tenth spine 53.9% length of first segmented ray; second anal-fin spine longest and stoutest; anal fin rounded with second segmented ray longest; caudal fin weakly emarginate (lower part of fin damaged); lower 9 pectoral fin rays slightly thickened, with membranes between thickened rays deeply incised; 11th (counting from dorsal-most) pectoral ray longest, reaching vertical through base of third anal-fin spine; pelvic fins short, almost reaching anus, second segmented ray longest.

Morphometric data are summarised in Table 18.

Mouth large, slightly oblique, posterior margin of maxilla reaching vertical through middle of pupil; maxilla expanded posteriorly, with long, low, lateral ridge running parallel to dorsal margin; small splint-like supramaxilla present; mouth terminal; upper jaw with 2 fixed, short stout outer canines on either side of symphysis, flanked internally by villiform band with about 8 rows of depressible, smaller, sharp-tipped teeth, with inner rows becoming progressively longer and caniniform near symphysis, band reducing to 2 rows posteriorly, the teeth on outer row largest; lower jaw with 2 stout canines at front of jaw, a band of villiform band of about 6 rows of small depressible teeth at symphysis, teeth becoming progressively longer on inner rows near symphysis, 3 enlarged, curved canines on middle of jaw, band narrows to single row posteriorly; vomer with V-shaped band of 3–4 rows of sharp-tipped conical teeth; palatine with a band of 2–3 rows of small, sharp-tipped conical teeth; ectopterygoid and mesopterygoid edentate; tongue narrow, pointed and edentate.

Opercle with 3 flat spines, middle spine longest, upper spine concealed by scales; preopercle with 20 serrations on posterior margin and 4 weak serrations or crenulations on ventral margin; interopercle with 0–2 crenulae; subopercle with 0–3 crenulae; posttemporal with 0–2 weak serrations. Anterior nostril positioned at middle of snout, tubular with small flap on posterior rim, flap reaching anterior margin of posterior nostril when depressed; posterior nostril at anterior border of orbit, with slightly raised rim but no flap.

Scales ctenoid with basal cteni; lateral line broadly arched over pectoral fin following body contour to caudalfin base; scales present on lower part of maxilla, all infraorbitals except first, and upper part of snout; no scales on chin, mandibles, branchiostegal membranes, or lower part of snout; no auxiliary scales on head or body; dorsal fin with intermittent row of scales along base of spinous part of fin, and broad sheath of scales on soft part of fin; anal fin with broad scaly sheath basally; caudal fin with scaly basal sheath, with small scales extending on to basal third to half of fin membranes; pectoral fins with basal sheath and small scales extending on to fin membranes.

Colour in life: Not known

Colour in preservative ( Figure 22A ): Head, body and fins mostly pale tan; broad blackish brown wedge extending from middle of dorsal fin (from bases of tenth spine through fourth segmented ray) down to about 6 rows below lateral line; indistinct small (subequal to pupil) grey-brown spot mid-laterally on posterior end of caudal peduncle, this extending slightly on to base of caudal fin; blackish brown wedge on body extending onto basal half of adjacent part of dorsal fin

Habitat and distribution. Known only from the holotype, trawled in 457–485 m off Bulli , New South Wales, Australia ( Figure 9 ).

Comparisons. Plectranthias grahami has a relatively high number of lateral-line scales, which is approached or equalled by only a handful of species: P. kelloggi from the Hawaiian Ridge and southern Emperor Seamount Chain with 34–38; P. randalli Fourmanoir & Rivaton, 1980 from the Chesterfield Islands, Sulawesi and Taiwan with 37–39; P. taylori Randall, 1980 from the Phoenix Islands with 40–41; P. exsul Heemstra & Anderson, 1983 from the Juan Fernández Islands with 40–46; P. parini Anderson & Randall, 1991 from Easter Island and the Sala y Gómez Ridge with 37–40; and P. nazcae Anderson, 2008 from the Nazca Ridge with 36–42. Plectranthias grahami is distinguished from: P. kelloggi in having more pectoral rays (18 versus 14–16) and different head scalation (mandible without scales versus with scales); P. randalli in having fewer segmented dorsal rays (15 versus 16–17) and more pectoral rays (18 versus 14); P. taylori in having fewer segmented dorsal rays (15 versus 18), more pectoral rays (18 versus 14) and different ornamentation of the ventral ridge of the preopercle (four weak crenulations versus two broad antrorse spines); P. exsul in having more pectoral rays (18 versus 16–17) and fewer circumpeduncular scales (18 versus 20–22); P. parini in having fewer segmented dorsal rays (15 versus 16), more pectoral rays (18 versus 15–16) and fewer gill rakers (6+13 versus 8+18–20); P. nazcae in having fewer segmented dorsal rays (15 versus 16), more pectoral rays (18 versus 16–17) and fewer gill rakers (6+13 versus 7–10+19–22). The preserved coloration and vertebral count (10+17 versus 10+16) also distinguish P. grahami from these species.

Remarks. The specific epithet is for Ken Graham, who collected the holotype, and has contributed extensively to our knowledge of New South Wales trawl fishes and invertebrates. He noted (pers. comm.) that this is the only specimen of the species he has ever collected, despite several decades of extensive exploratory trawling in similar depths off the New South Wales coast.

As noted under Remarks for Plectranthias , this species resembles Hypoplectrodes , Epinephelides and Othos in having 27 vertebrae, and a justification might be made for placement of the species in one or other of those genera. However, it differs from those three genera in having weak crenulations on the ventral margin of the preopercle (versus 2 large antrorse serrations in Epinephelides , 1 small antrorse serration in Othos and either 1–3 enlarged antrorse or 4 enlarged retrorse serrations in Hypoplectrodes ); scales on the maxilla (versus maxilla without scales in Epinephelides and Hypoplectrodes ); the upper part of the snout fully scaled (versus anterior part of snout without scales in Epinephelides and Hypoplectrodes ); 15 segmented dorsal rays (versus 20–21 in Epinephelides , 18–19 in Othos and 16–22 in Hypoplectrodes ); 7 segmented anal rays (versus 7–8, usually 8 in Epinephelides , 8 in Othos , and 7–9, usually 8 in all Hypoplectrodes except H. annulatus with 7–8, usually 7) and 41–42 tubed lateral-line scales (versus around 70 in Epinephelides , 81–87 in Othos and 38–65 in Hypoplectrodes , with only four of the 11 species having 42 or fewer tubed scales). Plectranthias grahami further differs from all three genera in having 1/1/1/1+1/1+1 dorsal pterygiophores in interneural spaces 9–13 (versus usually 1/1/1+1/1+1/1+1, rarely 1/1/1+1/1+1/1 for the other genera). In this latter character, P. grahami more closely resembles certain other Plectranthias species, such as P. alleni , P. azumanus , P. maculicauda , P. melanesius , P. kelloggi and P. exsul .

Figures

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

FIGURE 22. Plectranthias grahami n. sp., AMS I.18855-003, 122.5 mm SL, holotype, east of Bulli, New South Wales, Australia: A) Preserved; B) Radiograph. Photo by A.C. Gill; radiograph by A. Hay and S.E. Reader.