Plectranthias moretonensis, 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 : 93-95

Plectranthias moretonensis n. sp.

Figures 35 , 38 ; Tables 1–16, 18

English common name: Moreton Perchlet

Holotype. AMS I.35797-004, 31.5 mm SL, Australia, Queensland, east of Stradbroke Island , 27°27.37′S 153°39′E, 77 m, W.F. Ponder, HMAS Kimbla , 29 Mar 1969.

Diagnosis. Plectranthias moretonensis is distinguished from congeners in having the following combination of characters: dorsal rays X,16; third dorsal spine longest, bearing fleshy pennant; pectoral rays 13, all rays unbranched; lateral line complete, consisting of 27–29 tubed scales; predorsal scales extending anteriorly to vertical through posterior edge of pupil; preopercle finely serrated posteriorly, with two enlarged antrorse serrations ventrally.

Description. Dorsal rays X,16, all segmented rays branched; anal rays III,7, all segmented rays branched; pectoral rays 13/13, all rays unbranched; pelvic rays 1,5; principal caudal rays 9 + 8; branched caudal-fin rays?+6; upper procurrent caudal-fin rays 6; lower procurrent caudal rays 5; total caudal-fin rays 28; lateral-line complete with 29/27 tubed scales; scales above lateral-line to origin of dorsal fin 3/3; scales above lateral-line to base of fifth dorsal spine 2/2; scales below lateral line to origin of anal fin 10/11; diagonal rows of scales on cheek 5; predorsal scales about 12, extending to vertical through posterior edge of pupil; circumpeduncular scales 15; gill rakers 5+12, the upper four and lower four rudiments; branchiostegal rays 7; pseudobranch filaments 13.

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; no apparent trisegmental pterygiophores associated with dorsal fin; terminal dorsal pterygiophore in interneural space 18; no apparent 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 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 ( Figure 38B ).

Dorsal-fin spines with fleshy tabs on their distal tips; third dorsal spine longest; dorsal fin incised before first segmented-fin ray; second anal-fin spine longest and stoutest; anal fin slightly pointed with third segmented ray longest; caudal fin irregular, with several upper and central rays elongated past fin margin; lower 6 pectoral fin rays somewhat thickened, with membranes between thickened rays deeply incised; eighth (counting from dorsal-most) pectoral ray longest, almost reaching vertical through posterior edge of anal-fin base; pelvic fins short, not quite reaching anus, second segmented ray longest.

Morphometric data are summarised in Table 18.

Mouth large, slightly oblique, posterior margin of maxilla reaching vertical through posterior third of pupil; maxilla expanded posteriorly, with long, low, lateral ridge running parallel to dorsal margin; small splint-like supramaxilla present; upper jaw with 1–2 fixed, short stout outer canines on either side of symphysis flanked internally by villiform band with about 5 rows of depressible, smaller, sharp-tipped teeth, with inner rows becoming progressively longer and caniniform near symphysis, band reducing to 1 or 2 rows posteriorly; lower jaw with villiform band of about 5 rows of small depressible teeth at symphysis, teeth becoming progressively longer and caniniform near symphysis; band reducing to single row on posterior half of jaw; 1–2 stout canines on middle of jaw; vomer with 2 rows of conical teeth in V-shaped band; palatine with a band of 1–2 rows of small, conical teeth; ectopterygoid and mesopterygoid edentate; tongue narrow, pointed and edentate.

Opercle with 3 flat spines, middle spine longest, upper spine mostly concealed by scales; preopercle with 16/18 serrations on vertical portion, and 2 enlarged antrorse serrations on ventral portion; interopercle relatively smooth, without obvious serrations or crenulations; subopercle smooth; posttemporal with 7/6 irregular serrations; no serrations on first infraorbital bone. Anterior nostril tubular, positioned at middle of snout; posterior nostril at mid-upper, anterior border of orbit with slightly raised rim.

Scales ctenoid with peripheral cteni; lateral line broadly arched over pectoral fin following body contour to caudal-fin base; no scales on mandibles, chin, branchiostegals, maxilla, snout, infraorbitals, lips and anterior interorbital area; no auxiliary scales on head or body; no scales on dorsal fin; low scaly sheath on basal part of anal fin; caudal fin with scaly basal sheath, with small scales extending over basal third of fin; pectoral fins with basal, wedge-shaped sheath of small scales.

Colour in life: Not known

Colour in preservative: Head, body and fins generally pale tan, except for a few dusky spots dorsally on nape and occiput ( Figure 38A ).

Habitat and distribution. Known only from the holotype, trawled in 77 m, east of Moreton Bay , Queensland ( Figure 35 ).

Comparisons. Plectranthias moretonensis does not key to any species using Randall (1996), as it contradicts information for both alternatives at couplet 35. There are three species listed by Randall at and after couplet 35: P. altipinnatus Katayama & Masuda, 1980 from southeastern Japan, P. vexillarius Randall, 1980 from the Gulf of Oman and P. pelicieri Randall & Shimizu, 1994 from Mauritius, South Africa ( Heemstra & Randall 2009), southern Japan ( Senou & Yunokawa 1995) and New Caledonia ( Fricke et al. 2015). Plectranthias moretonensis is readily distinguished from P. altipinnatus in having fewer segmented dorsal rays (16 versus 18) and from both P. altipinnatus and P. vexillarius in having 2 antrorse (versus no) serrations on the lower edge of the preopercle. It further differs from P. vexillarius in having fewer circumpeduncular scales (15 versus 18), fewer segmented dorsal rays (16 versus 17) and less extensive coverage of predorsal scales (extending to vertical through posterior edge of pupil versus almost to posterior nostrils). It differs from P. pelicieri in having more extensive coverage of predorsal scales (reaching only to vertical through posterior edge of preopercle in P. pelicieri ), and a different predorsal formula (0/0/2/1+1 versus 0/0+0/2/1+1). The following combination of characters distinguishes P. moretonensis from all other Plectranthias species described subsequent to Randall (1996): dorsal rays X,16, with the third spine longest; pectoral rays 13, all unbranched; lateral line complete with 27–29 scales; preopercle with 2 antrorse serrations ventrally; and predorsal scales extending to vertical through posterior edge of pupil.

Remarks. The specific epithet refers to the type locality, off Stradbroke Island, Moreton Bay, Queensland.

Figures

FIGURE 35. Distribution records for P. mcgroutheri (open circles; arrow indicates type locality), Australian specimens of P. retrofasciatus (closed circles) and P. moretonensis (triangle).

FIGURE 38.Plectranthias moretonensis n. sp.,AMS I.35797-004, 31.5 mm SL, holotype, east of Stradbroke Island,Queensland, Australia: A) Preserved; B) Radiograph. Photo by A.C. Gill; radiograph by A. Hay and S.E. Reader.