Erdmannichthys, Conway & Fujiwara & Motomura & Summers, 2021

Conway, Kevin W., Fujiwara, Kyoji, Motomura, Hiroyuki & Summers, Adam P., 2021, Erdmannichthys, a new genus of Gobiesocidae (Teleostei: Gobiesociformes), and notes on the rare clingfish E. alorensis (Allen & Erdmann, 2012), new combination, Raffles Bulletin of Zoology 69, pp. 428-437 : 429-431

Erdmannichthys , new genus

Diagnosis. A genus of the subfamily Diademichthyinae sensu Conway et al. (2020) , distinguished from all other genera of this subfamily by the presence of a prominent dark reddishbrown oval to triangular marking at base of caudal fin ( Figs. 3 , 4 ). The new genus is distinguished from Diademichthys , Discotrema, Flabellicauda , “ Lepadichthys ”, Lepadicyathus and Unguitrema by having a double adhesive disc ( Fig. 5 ) (vs. single adhesive disc). It is distinguished from the remaining diademichthyine genera (viz. Aspasma , Aspasmichthys , Aspasmodes , Briggsia , Flexor , Liobranchia , Lissonanchus , Pherallodus , Pherallodichthys and Propherallodus ), all with a double adhesive disc, by the presence of three white lines on the body surface in life ( Figs. 3 , 4 ), including a mid-dorsal stripe (originating on tip of snout posterior to upper lip and extending to dorsal-fin origin) and a pair of dorsolateral stripes (originating on dorsolateral part of snout adjacent to anterior nostril and extending posterior, through upper part of eye, to area on upper body side close to caudal fin base) (vs. colour pattern in life largely uniform, with smaller indistinct dark markings [ Aspasma , Aspasmodes , Briggsia , Flexor and Lissonanchus ] or with prominent darker stripes, saddles or other markings [ Aspasmichthys , Pherallodus , Pherallodichthys and Propherallodus ] but without prominent white lines along long axis of body; life colour unknown for Liobranchia ). It is further distinguished from the other diademichthyine genera with a double adhesive disc by the following combination of characters: gill membranes united and free from isthmus forming single continuous gill opening ( Figs. 4 , 5A ) (vs. gill membranes connected to isthmus restricting gill opening to side of head in Aspasma , Aspasmichthys , Aspasmodes , Briggsia , Liobranchia , Lissonanchus and Pherallodichthys ); papillae of disc region A continuous across centre ( Fig. 5A, B ) (vs. centre of region A without papillae in Aspasma , Aspasmichthys [ Fig. 5C, D ] and Pherallodus ); mandibular portion of preoperculo-mandibular lateral-line canal absent ( Fig. 6C ) (vs. present on anguloarticular in Aspasmichthys ); preopercular portion of preoperculo-mandibular lateral-line canal with two pores (PR1 and PR3) only ( Fig. 6B, C ) (vs. three pores, PR1–3, in Aspasma , Aspasmichthys , Flexor and Propherallodus , preopercle without canal in Briggsia , Lissonanchus and Pherallodus ); presence of a small oval gap in dorsal view between anterior tips of premaxillae formed by a semicircular indentation along medial edge of premaxilla ( Fig. 6A ) (vs. minute square gap in Aspasma , medial edge of premaxilla straight, without gap between premaxillae in Aspasmodes , Liobranchia and Pherallodichthys ); subopercle poorly ossified, posterior margin rounded ( Fig. 6B, C ) (vs. subopercle well ossified, posterior edge with spine-like posterior process in Aspasmichthys ).

Etymology. Named for Mark V. Erdmann, in honour of his work on Indo-Pacific reef fishes. Gender masculine.

Type species. Aspasmichthys alorensis Allen & Erdmann, 2012 , by present designation.

Material examined. WAM P.34629-001, 1 (photograph only), 13.3 mm SL; WAM P.34629-005, 1 (preserved in ethanol [DNA voucher]), 9.1 mm SL (CT, https://doi.

org/10.17602/M2/M388066); Indonesia: Nusa Tenggara Province: submerged reef off south east coast of Padar island, Komodo Group , 10 metres depth, 08°41.284′S, 119°34.528′E, M. V. Erdmann and A. Sianipar (MVE-16-051) .

Figures

Fig. 3. Five individuals of Erdmannichthys alorensis photographed by M.V. Erdmann at a submerged reef (10 metres depth) off south east coast of Padar island, Nusa Tenggara Province, Indonesia. A–C. Not collected, not measured. D. Potentially WAM P.34629-001, 13.3 mm SL; E–F. Potentially WAM P.34629-005, 9.1 mm SL.

Fig. 4. Erdmannichthys alorensis, WAM P.34629-005, 9.1 mm SL; Indonesia, Nusa Tenggara Province. Dashed white circles highlight location of cephalic lateral line canal pores. Abbreviations: LC1, 2, lachrymal pore 1, 2; NC1, 2, nasal pore 1, 2; PO1, 2, postorbital pore 1, 2; PR1, 3, preopercular pore 1, 3.

Fig. 5. A. Photograph of adhesive disc of Erdmannichthys alorensis, WAM P.34629-005, 9.1 mm SL; anterior margin of disc inserted under gill membrane; dashed grey line highlights posterior margin of gill membrane. B. Schematic line drawing of adhesive disc in A. C. Photograph of adhesive disc of Aspasmichthys ciconiae, KAUM–I. 147568, 43.1 mm SL; disc treated with Cyanine blue (following Saruwatari et al., 1997). D. Schematic line drawing of disc in C. Abbreviations: A–C, adhesive disc regions A–C; GM, gill membrane; LM, larval melanocyte.

Fig. 6. CT scanned anterior skeleton, including cranium, paired-fin girdles and abdominal region of vertebral column, of Erdmannichthys alorensis WAM P.34629-005, 9.1 mm SL. A. Dorsal view. B. Lateral view of right side (image mirrored). C. Ventral view. Right side of specimen damaged. Cephalic lateral line canals highlighted in green. Pores of cephalic lateral line system orange. Anteriormost epicentral (epicentral 2) highlighted in aqua blue. Dorsal postcleithra highlighted in pink. Ventral postcleithra highlighted in yellow. Outline of subopercle highlighted with thin white line in B, C. Abbreviations: ACh, anterior ceratohyal; Ana, angulo-articular; Apa, autopalatine; Boc, basioccipital; Bp, basipterygium; Br, branchiostegal rays; Cb, ceratobranchials; Cl, cleithrum; Cor, coracoid; DHh, dorsal hypohyal; DPcl, dorsal postcleithrum; Ec2, 6, epicentral 2, 6; Ect, ectopterygoid; EPC, epiphyseal commissure; Epoc, epiotic; Exoc, exoccipital; Fr, frontal; Hy, hyomandibular; I, pelvic-fin spine; Iop, interopercle; LC, lachrymal canal; LC1, 2, lachrymal pore 1, 2; LE, lateral ethmoid; Na, nasal; NC1, 2, nasal pore 1, 2; NS1, 5, neural spine of vertebral centrum 1, 5; Op, opercle; Pa, parietal; PecR, pectoral radial; PecFR, pectoral-fin ray; PelFR1–4, pelvic-fin ray 1–4; PO1, 2, postorbital pore 1, 2; Pop, preopercle; PRC, preopercular canal; PR1, 3, preopercular canal pore 1, 3; Pro, prootic; Psph, parasphenoid; Pt, posttemporal; Pte, pterotic; Q, quadrate; Ra, retroarticular; Ri, ribs; Sc, scapula; Scl, supracleithrum; Soc, supraoccipital; Sop, subopercle; SPC, supraorbital canal; Sph, sphenotic; STC, stomach content; Ur, urohyal; V1, vertebral centrum 1; Vo, vomer; VPcl, ventral postcleithrum.