Plectranthias cruentus Gill & Roberts 2020, new species
Creators: name: Gill, Anthony C.
name: Roberts, Clive D.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Perciformes
Serranidae
Plectranthias
Plectranthias cruentus

description: Plectranthias cruentus new species
Figures 1–2; Table 1
Common name: Bloody Perchlet
Plectranthias sp C.— Williams et al., 2006: 29 (colour photo of holotype); Clark & Roberts, 2008: 51, fig. 18 (colour photo of holotype).
Holotype. AMS I.42725-007, 57.3 mm SL, Australia, Lord Howe Island, off Ball’s Pyramid, from 31°49.11’S, 159°20.74’E to 31°49.44’S, 159°20.39’E, 86–89 m, Sherman sled, R. V. Tangaroa, 22 May 2003 (NORFANZ TAN 0308 /061).
Paratypes. AMS I.12854, 43.0 mm SL, Australia, Lord Howe Island, P. R. Pedley, 1913; NMNZ P.039081, 52.7 mm SL, collected with holotype; NMNZ P. 061156, 44.4 mm SL, collected with holotype.
Non-type specimen. AMS I.35797-007, Australia, Queensland, off Moreton Bay, 27°27.37’S, 153°39’E, 77 m (stated depth 42 fathoms), W.F. Ponder aboard RANS Kimbla, 29 Mar 1969.
Diagnosis. The following combination of characters distinguishes P. cruentus from all known congeners: dorsal rays X,16–17, fifth or sixth spine longest; pectoral-fin rays 13, at least some middle rays branched, upper 5 or more unbranched; predorsal scales extending forward only to supratemporal commissure. Live coloration: dorsal and lateral body bright orange, becoming yellow-orange ventrally, crossed by narrow, red-edged pink oblique bars, which also extend along base of anal fin; posterior part of caudal peduncle with distinct, broad orange-red bar, caudal fin yellow; pectoral fins translucent orange-pink; pelvic fins bright yellow, tipped with orange.
Description. Dorsal rays X,17 (16 f 2; 17 f 1), all segmented rays branched; anal-fin rays III,8 (III,7 f 3), all segmented rays branched; pectoral-fin rays 13/13, upper 5/5 (5–7) and lower 1/1 (0–3) rays unbranched; pelvic fin I,5, all segmented rays branched; upper procurrent caudal-fin rays 6; lower procurrent caudal-fin rays 6 (5 f 1; 6 f 2); principal caudal-fin rays 9 + 8; branched caudal-fin rays 7 + 7; total caudal-fin rays 29 (28 f 1; 29 f 2); lateral line complete with 29/29 (29 f 5; 30 f 1) tubed scales; scales above lateral line to origin of dorsal fin 3/3; scales above lateral line to base of fifth dorsal spine 3/3 (2 f 1; 3 f 3; 4 f 2); scales below lateral line to origin of anal fin 11/11; diagonal rows of scales on cheek 5 (5 f 2; 6 f 1); predorsal scales 7, extending anteriorly to supratemporal commissure, at vertical above preopercle margin; circumpeduncular scales 14; gill rakers 5+13 (5 + 12 f 1; 5 + 13 f 1; 5 + 14 f 1), the upper 4 and lower 5 (5–6) rudiments; pseudobranchial filaments 18 (14–17); branchiostegal rays 7.
Vertebrae 10 + 16; supraneurals 3; predorsal formula 0/0 + 0/2/1 + 1; no trisegmental pterygiophores associated with dorsal and anal fins; ribs present on vertebrae 3 through 10; epineurals present on vertebrae 1 through 15 (14–15); parhypural and all hypurals autogenous (i.e., not “fused” to each other); 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; no parapophyses on first caudal vertebra (Figure 2).
Fleshy tabs present on distal tips of at least dorsal-fin spines 4 through 7 (and possibly on spine 3; tabs shrink when preserved, and are thus often difficult to see); sixth (fifth or sixth) dorsal spine longest; dorsal fin incised before first segmented fin ray; ninth (sixth to eighth) segmented dorsal ray longest; second anal-fin spine longest and stoutest; anal fin rounded with second or third segmented ray longest; caudal fin emarginate with upper lobe longer than lower lobe; lower 6 pectoral fin rays thickened, with membranes between thickened rays deeply incised; eighth (counting from dorsal-most) pectoral-fin ray longest, reaching vertical through base of second or third segmented anal-fin ray; second segmented pelvic-fin ray longest, relatively short, varying from just short of anus to reaching vertical through base of first segmented anal-fin ray.
Morphometric values are summarised in Table 1.
dard length (SL). –, no data (broken).
Mouth large, slightly oblique, posterior margin of maxilla reaching just beyond vertical through posterior edge of orbit; small splint-like supramaxilla present; maxilla expanded posteriorly, with long, low, lateral ridge running parallel to dorsal margin; mouth terminal; upper jaw with 1–2 fixed, stout outer canines at front of jaw; behind these a band of small conical teeth, about 3–4 rows wide at symphysis reducing to 2 rows posteriorly on sides of jaw, the outer row teeth slightly larger and curved; teeth in anterior part of band depressible, those nearest symphysis enlarged and caniniform; teeth in lower jaw similar to upper jaw, except inner row teeth in band slightly enlarged and curved, and 1–2 enlarged canine teeth in outer row, about midway along jaw; vomer with V-shaped band of 2 rows of small conical teeth; palatine with 2 rows of small conical teeth arranged in elongate oval patch; ectopterygoid and mesopterygoid edentate; tongue narrow, pointed and edentate.
Opercle with 3 flat spines, middle spine longest, upper spine relatively small; preopercle with 34/32 (19–32) serrations on posterior margin, these largest ventrally, and additional 2/3 (2) enlarged antrorse serrations on ventral margin; interopercle with 2/2 (1–3) small, inconspicuous serrations; subopercle with 0 (0–6) small, inconspicuous serrations; exposed portion of posttemporal with 6/6 (3–4) irregular serrations. Anterior nostril positioned on posterior third of snout, close to posterior nostril, in short tube with small flap on posterior rim; posterior nostril at anterior border of orbit, subtriangular with slightly raised rim but no flap.
Scales ctenoid with peripheral cteni and no basal cteni; lateral line broadly arched over pectoral fin following body contour to caudal-fin base; no scales on chin, mandibles, branchiostegal membranes, maxilla or snout; no auxiliary scales on head or body; intermittent row of scales along base of posterior part of spinous dorsal fin, becoming low scaly sheath, 2–3 rows high over basal part of soft dorsal; anal fin with low scaly sheath basally, 1–2 rows high; caudal fin with scaly basal sheath; pectoral fins with basal scaly sheath.
Colour in life: Head and body bright orange, becoming bright yellow-orange ventrally; two indistinct red-edged pink stripes beneath eye extending to first infraorbital, one from mid-ventral edge of orbit, the other from posterior edge of orbit; scales on cheek each with red-edged pink spot, these aligning to form three oblique stripes that extend, respectively, to pelvic fin origin, space between bases of pelvic and pectoral fins, and lower edge of pectoral-fin base; operculum with two large (subequal to pupil) red-edged, bright yellow spots; iris red, with short dark bar anteriorly, bright yellow spots ventrally and posteriorly and narrow yellow ring around pupil; scales of dorsal body each with a pink spot, these aligning on the lateral and ventral body to become narrow, red-edged pink oblique bars, each alternating with c.15 slightly oblique yellow bars, narrow dorsally, expanding to at least twice the width ventrally, extending to ventral profile of body and across anal fin; caudal peduncle with a distinctive broad vertical orange-red bar near caudal base, edged anteriorly with contrasting broad pale pink bar, and orange-yellow posteriorly; spinous portion of dorsal fin pale pink, spine tips and fleshy tabs bright orange-yellow to bright yellow; soft rays of dorsal fin yellow, becoming bright orange-yellow distally and narrowly pale pink basally; basal part of dorsal fin with five indistinct reddish orange blotches, first between 5 th and 6 th spines, second between 8 th and 9 th spines, third between 1 st and 5 th segmented rays, fourth between 7 th and 10 th segmented rays, fifth between 12 th and 17 th segmented rays; anal rays bright yellow, red on distal margin, with red bars on body extending on to base of fin, breaking up to become one (anteriorly) to three (posteriorly) rows of red streaks; caudal fin orange-yellow basally, becoming pale yellow posteriorly, with upper and lower margins of fin narrowly red; pelvic fin spine orange-red, the remainder of fin bright orange-yellow basally, becoming bright orange-red distally, with distal tip black; pectoral fin translucent reddish orange.
Colour in preservative: Generally pale tan, with no dark markings except blackish tip on second pelvic-fin ray.
Habitat and distribution. Known from the holotype and two paratypes collected at 86–89 m off Ball’s Pyramid, south-east of Lord Howe Island, and from a paratype collected by P.R. Pedley at Lord Howe Island in 1913. Possibly occurs off southeast Queensland, Australia (see Remarks).
Comparisons. Plectranthias cruentus closely resembles P. pelicieri Randall & Shimizu (1994) in live coloration, and most meristic and morphometric details. The latter species was initially described from Mauritius but was subsequently reported from southern Japan by Senou & Yunokawa (1995), from South Africa by Heemstra & Randall (2009), and from New Caledonia by Fricke et al. (2015). The two species are unique among Plectranthias species in having the predorsal scales extend anteriorly only to the supratemporal canal, at a vertical above the preopercle (versus to a vertical through the posterior edge of the orbit or further forward in congeners). Plectranthias cruentus is readily distinguished from P. pelicieri in having: some middle pectoral-fin rays branched (versus all unbranched in P. pelicieri), the fifth or sixth dorsal-fin spine longest (versus third longest), and interopercle with 1–3 small, inconspicuous serrations (versus “distinctly serrate anteriorly” according to Heemstra & Randall, 2009). Plectranthias cruentus also differs from P. pelicieri in the following live coloration details (cf. Figures 1 and 3): caudal fin yellow (versus clear with yellow or orange spots); operculum with two red-edged yellow pupil-sized spots (versus with a single eye-sized red and yellow ocellus); and posterior part of caudal peduncle with broad orange-red bar (versus pink with orange-red spots or rectangular markings dorsally and ventrally).
Etymology. The specific epithet is from the Latin, meaning stained or spotted with blood, and alludes to the bright red markings in life.
Remarks. A 37.4 mm SL specimen collected at 77 m off Moreton Bay in 1969 by W.F. Ponder (AMS I.35797- 007) is possibly referable to this species. The specimen agrees in all salient features with the type specimens (including characters listed in the diagnosis), but we treat the identification and distribution record of this specimen as tentative, pending the discovery of additional specimens. We therefore excluded the specimen from the type series.
description: Published as part of Gill, Anthony C. & Roberts, Clive D., 2020, Plectranthias cruentus, a new species of anthiadine perchlet (Teleostei: Serranidae) from the Lord Howe Rise, Tasman Sea, pp. 560-566 in Zootaxa 4750 (4) on pages 561-565, DOI: 10.11646/zootaxa.4750.4.6, http://zenodo.org/record/3708866