Filamentous Perchlet, Plectranthias robertsi Randall & Hoese 1995

Illustration of the holotype of the Filamentous Perchlet, Plectranthias robertsi, AMS 1.20968-003, 78.4 mm, female, from E of Hinchinbrook Island, depth 320-356 m. Source: Francisco Neira, Fig. 1, in Randall & Hoese (1995) Records of the Australian Museum 47(3): 327-335. License: CC By Attribution-NonCommercial-ShareAlike

A perchlet with 15 soft dorsal-fin rays, 16 pectoral-fin rays, 32-35 lateral-line scales, filamentous upper caudal-fin rays, and extremely prolonged second dorsal and second pelvic rays in the male.

Cite this page as:
Bray, D.J. 2021, Plectranthias robertsi in Fishes of Australia, accessed 14 Jun 2024,

Filamentous Perchlet, Plectranthias robertsi Randall & Hoese 1995

More Info


Trawled in the Coral Sea off Queensland from 18-23° S in the depths of 220-400 m. 


Dorsal fin X,15 (all rays branched, the last to base); Anal fin Ill,7 (all rays branched, the last to base); Pectoral fin 15-16 (mostly 16, uppermost and lower four to eight rays simple); Pelvic fin 1,5; Branched caudal-fin rays 8+7, upper and lower simple segmented caudal rays 3, upper and lower procurrent caudal rays 4; Lateral line complete, pored scales 32-35; scales above lateral line to origin of dorsal fin 3; scales below lateral line to origin of anal fin 10 (9.5-10); circumpeduncular scales 15; diagonal rows of scales on cheek 7; Gill rakers 6-7+ 13-14; Pseudobranchial filaments 23 (18-27); Branchiostegal rays 7; Vertebrae 10+16; Scales above lateral line to origin of dorsal fin 3; Scales dorsally on head extending to posterior nostrils; Scales present on maxilla; 
Body depth 2.6-3.2 in SL; margin of preopercle finely serrate, without antrorse spines on ventral edge; fourth or fifth dorsal spine longest, 2.6-3.1 in SL; second dorsal soft ray longest, prolonged as a filament in males; second pelvic soft ray longest, greatly prolonged as a filament in males; caudal fin emarginate, the second to fourth branched rays filamentous (but easily broken); pale in alcohol with a blackish spot on first four or five lateral-line scales and adjacent scales of the row above. 


Tan, becoming silvery white over abdomen and thorax, with some silvery iridescence on opercle; first four lateral-line scales dusky, with some dark pigment on adjacent scales above; a faint narrow yellow stripe extending from eye to anterior lateral line; some indistinct faint yellow to yellow-orange blotches of about pupil size barely detectable on the photograph, one series of about four dorsally on body at base of dorsal fin and a second series along side of body; snout dusky yellowish, the upper lip more yellow; lower jaw dusky orangish, this colouration more intense anteriorly; median fins pale yellowish (more yellow on the dorsal than the anal and caudal); paired fins whitish; iris a mixture of yellow and blackish (Randall & Hoese 1995).


The species is named robertsi in honour of Clive D. Roberts who first recognised it as an undescribed species from a single specimen taken in Capricorn Channel off Queensland and had plans to name it when more material was collected. When he heard of our research on the species, he kindly made his specimen available to us. 

Species Citation

Plectranthias robertsi Randall & Hoese 1995. Rec. Aust. Mus. 47(3): 328, fig. 1. Type locality: off Hinchinbrook Island, Queensland.


Bray, D.J. 2021


Australian Faunal Directory

Filamentous Perchlet, Plectranthias robertsi Randall & Hoese 1995


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

Randall, J.E. 1996. Two new anthiine fishes of the genus Plectranthias (Perciformes: Serranidae), with a key to the species. Micronesica 29(2): 113-131.

Randall, J.E. & Hoese, D.F. 1995. Three new species of Australian fishes of the genus Plectranthias (Perciformes: Serranidae: Anthiinae). Records of the Australian Museum 47(3): 327-335. Ref available online Open access

Quick Facts

CAAB Code:37311180

Depth:220–400 m

Habitat:Reef associated

Max Size:11.5 cm SL


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