Brachiopsilus dossenus, Last & Gledhill Csiro, 2009

Last, Peter R. & Gledhill Csiro, Daniel C., 2009, A revision of the Australian handfishes (Lophiiformes: Brachionichthyidae), with descriptions of three new genera and nine new species 2252, Zootaxa 2252 (1), pp. 1-77 : 25-27

Brachiopsilus dossenus sp. nov.

Figs 2 , 3 , 10, 12; Tables 1, 7–10

Holotype. NMV A 29405–002 , 65.0 mm SL, off Marlo, Bass Strait , Victoria, 38° 27'S, 148° 26'E, 226 m, 10 Sep. 1984.

Paratypes. 2 specimens (52–54 mm SL): CSIRO H 4119–02 , 54.4 mm SL, east of Maria Island , Tasmania, 42° 43'S, 148° 24'E, 87–152 m, 5 Nov. 1984 ; CSIRO T 195 , 52.4 mm SL, east of Flinders Island , Tasmania, 40° 00'S, 148° 47'E, 20 m, 13 Apr. 1984 .

Diagnosis. Member of the genus Brachiopsilus with a combination of the following characters: esca small, 23–30% of illicium length; illicium smooth, thin, not exceedingly fleshy, length 13–16% SL, 3.1–3.6 times in head length, 2.1–2.3 times in length of second dorsal-fin spine; apex of esca situated above anterior half of eye when illicium adpressed; esca slightly wider than illicial stem, covered with dense, short, filaments; head slightly compressed; eye large (horizontal diameter 7–9% SL); mouth narrow; lips fleshy with prominent vertical folds; body and fins entirely naked (except for scales associated with pores of the acoustico-lateralis system and minute, deeply embedded scale and spinule fragments); long first dorsal-fin base (length 29–30% SL); second dorsal-fin rays 17, fin base 77–79% SL; length of second dorsal-fin spine 1.1–1.2 times length of longest ray of second dorsal fin; 10 anal-fin rays, length of anal-fin base 40–44% SL; 9 pectoral-fin rays; caudal peduncle short, length about 2% SL; caudal fin elongate, its length much longer than fin rays of pectoral fin, length 4.1–5.2 times caudal peduncle depth; body colour off white with yellowish patches on sides, uniformly white in preservative.

Description. D1 2 (2, n= 2 paratypes); D2 17 (17); A 10 (10); Pc 9 (9); Pv i, 4 (i, 4); C 1 (1) + 6 (5–6) + 2 (2–3) = 9 (9); Vt 9 (9–10) + 13 (13–14) = 22 (23).

Body elongate, moderately compressed anteriorly, not bulbous; upper anterior profile strongly convex, blunt, almost truncate anteriorly; upper eye slightly below anterodorsal margin; all of eye above level of illicial base; head subtriangular to dome-shaped when viewed anteriorly; nape humped prominently; anterior ventral profile almost straight to pelvic fin; abdomen not expanded; caudal peduncle short, length 2 (0–2)% SL. Head length 48 (49–50)% SL; snout short, 6.4 (5.7) times in head; eye medium-sized, lateral, not embedded or protruding, 6.7 (5.8–6.6) times in head length; gill opening small, aperture slightly smaller than pupil, located adjacent and directly posterior to insertion of pectoral fin. Nostrils enlarged, openings usually obvious; anterior opening tubular, almost abutting upper jaw; posterior opening not expanded, almost dorsal to anterior opening, close to orbit, upper edge just below level of mid orbit. Mouth very narrow, terminal, moderately protrusible; upper jaw almost horizontal, 4.1 (3.8–3.9) in head; lips fleshy, densely covered with papillose folds; angle of jaw recessed into groove, situated below hind margin of eye; jaws connected by narrow membrane at about a third of their length from angle; tongue broadly rounded apically. Teeth small villiform to subconical, similar in shape and size in both jaws; in bands, moderately broad anteriorly (4–6 teeth wide in holotype, but not in defined rows), becoming narrower posteriorly, extending almost to angle of jaw in paratype CSIRO H 4119–02; vomer edentate.

Skin thickened, flabby in paratypes, surface uniformly naked (apart from scales associated with sensory pores) on body and fins; minute, deeply embedded scale and spinule fragments evident under skin of semitranslucent paratype CSIRO H 4119–02; skin without wart-like patches, instead smooth or with low dermal ridges (appearing as wrinkles); dermal ridges mostly arranged horizontally on dorsal surface and tail, mostly vertically on sides of head; no obvious dermal flap present on mid-arm of pectoral fin; dermal flaps absent from body. Illicium with covering of thin, smooth skin; skin not papillose nor forming a loose covering around supporting ray; stem almost uniform in width along length of illicium. Acoustico-lateralis system well developed; scales bicuspid; spinules strongly elevated, evident without staining, spine apices overlain with papillose integument; sensory scales separated more or less evenly on tail; sensory scales highly prominent around mouth, on side of head and forehead (4 above eye), and on tail; sensory canals barely detectable; lateral line raised slightly over pectoral-fin base, extending along middle of tail to basal caudal rays.

Illicium relatively short, terminal on snout, 3.6 (3.1–3.4) times in head, (2.1–2.3) times in length of second dorsal-fin spine; apex of esca extending to just above eye when fin depressed; partly retractable into distinct groove on either side of first dorsal fin; esca small, sparsely covered with short globular filaments, 4.2 (3.3– 4.3) times in length of illicium, emanating from a narrower stem; illicial base not enlarged. First dorsal fin low, base moderately elongate; spines thickened slightly; second dorsal-fin spine (damaged in holotype) distinctly separate from base of illicium, longer than third spine; fin membrane thickened, expanded over bases of spines; membrane weakly connected by fleshy ridge or separated slightly from second dorsal fin; anterior elements of both fins very strongly recurved; first dorsal-fin base 2.6 (2.7) times in second dorsal-fin base. Second dorsal fin not well elevated, nor incised; rays simple; fin base very elongate, 77 (78–79)% SL; longest ray of second dorsal fin 1.1–1.2 times in longest dorsal-fin spine; basal membrane thickened, concealing bases of fin rays. Anal-fin margin weakly incised, rays moderately elongate, penultimate posterior rays longest; anal-fin base covered with well-developed membrane, 1.9 (1.8–1.9) times in second dorsal-fin base. Pectoral fin very elongate, enlarged, prominently arm-like, elbow extending well beyond gill opening, arm broadly connected to side of body by skin restricting extension anteriorly; fin rays slender, membranes deeply incised, tips long, flexible. Pelvic fin moderately well developed; rays narrow, deeply incised; anterior spine short, indistinct; rays not deeply embedded; fin located on ventral surface, directed ventrolaterally, base aligned horizontally, extended below ventral profile; interpelvic space narrow, almost flat. Caudal fin elongate, margin narrowly rounded; much larger than rayed portion of pectoral fin, length 4.1 (4.1–5.2) times caudal peduncle depth.

Coloration. In life (based on the holotype and only specimen for which the coloration has been observed): Reported by collector Peter Moulton as being ‘off white with light yellow patches on sides’.

In preservative: Uniformly plain white; fins and body semi-translucent in paratype CSIRO H 4119–02; eye bluish black.

Size. Attains at least 65.0 mm SL; smallest specimen examined 52.4 mm SL (ca. 89 mm TL). Size of newly hatched young and egg capsule diameter unknown.

Distribution. Demersal, recorded from off Marlo, Victoria (ca. 38° 27'S, 148° 26'E), and Flinders Island, Tasmania, in eastern Bass Strait (ca. 40° 00'S, 148° 47'E); and from off Maria Island, eastern Tasmania (ca. 42° 43'S, 148° 24'E). Collected at depths of 20– 226 m.

Etymology. Epithet based on the Latin dossenus (humpback or hunchback) in reference to the pronounced fleshy hump on its back between the snout and second dorsal fin. Proposed vernacular name: Humpback Handfish.

Comparisons. The two species, Brachiopsilus dossenus and B. dianthus , differ from each other in coloration, and in some meristic and morphometric characters. The only colour details for B. dossenus indicate that it is whitish with yellowish markings on the sides whereas B. dianthus is almost uniformly bright pink with a dark margin on the second dorsal fin. As its name implies, the nape of B. dossenus is strongly humped in all specimens. A similar-sized individual of B. dianthus (CSIRO A 1901, 68 mm SL), while possibly affected by preservation, is more compressed, has a much longer snout, smaller eye and shorter fin bases than the B. dossenus types. The following proportions can be used to distinguish available specimens of these species: total length 137–144 vs. 131–138% SL in B. dianthus , esca length 3.1–4.5 vs. 4.7–5.6% SL, second dorsal-fin base 77–79 vs. 73–76% SL, distance from snout to second dorsal-fin origin 34–36 vs. 31– 35% SL, length of anal-fin base 40–44 vs. 38–39% SL, distance from snout to anal-fin origin 55–59 vs. 61– 69% SL, body depth (at origin of second dorsal fin) 38–39 vs. 35–38% SL, eye (horizontal diameter) 7.1–8.6 vs. 5.8–7.1% SL; and esca length 23–30 vs. 29–38 times illicium length, head length 5.8–6.7 vs. 7.7–8.8 times eye length, longest dorsal-fin spine 1.1–1.2 vs. 1.3–1.5 times longest ray of second dorsal fin, and caudal-fin length 4.1–5.2 vs. 3.3–4.0 times caudal peduncle depth. Brachiopsilus dossenus has 9 (rather than mainly 10) pectoral-fin rays, 10 (rather than 9–10) anal-fin rays, 17 (rather than 17–18) dorsal-fin rays, and 13–14 (rather than 12–13) caudal vertebrae.

Remarks. A paratype of Brachiopsilus dossenus (CSIRO H 4119–01) was collected on station 168 of FRV Soela voyage 05/1984, on November 4 th, 1984, along with a specimen of Thymichthys verrucosus (CSIRO H 4119–02). It was fortuitously caught off Maria Island, eastern Tasmania, on the final station of a four week research voyage using a midwater trawl at 88–153 m, over an average bottom depth of 480 m; three handfish specimens (two above and a third unlocated) were caught (based on a detailed catch composition list) when the net grounded near the shelf break. The survey, which included sampling with a benthic sled and numerous demersal trawl stations, yielded only one other handfish specimen (paratype of Pezichthys eltanini sp. nov., NMV A 4282), but no other handfishes were recorded. The continental shelf and slope of southeastern Australia has been sampled on numerous occasions with benthic sleds and trawl nets. The incidental catch of three rarely caught fishes in a wayward pelagic trawl reflects the patchy distribution of handfishes.

Figures

FIGURE 2. Illustrations of the illicium and esca of: A. Brachionichthys australis, CSIRO H 4114–07, 55.8 mm SL; B. Brachionichthys hirsutus, CSIRO T 7, 78.9 mm SL; C. Brachiopsilus dianthus sp. nov., CSIRO H 4995–01, holotype, 99.5 mm SL; D. Brachiopsilus dossenus sp. nov., NMV A 29405–002, holotype, 65.0 mm SL; E. Brachiopsilus ziebelli sp. nov., CSIRO T 1993–01, holotype, 101.5 mm SL; F. Pezichthys amplispinus sp. nov., CSIRO H 4460–01, 37.2 mm SL; G. Pezichthys compressus sp. nov., CSIRO H 4447–01, holotype, 42.4 mm SL; H. Pezichthys eltanini sp. nov., LACM 11516–1, holotype, 30.0 mm SL; I. Pezichthys macropinnis sp. nov., CSIRO H 5317–02, holotype, 20.5 mm SL; J. Pezichthys nigrocilium sp. nov., CSIRO H 6154–01, holotype, 40.8 mm SL; K. Sympterichthys moultoni sp. nov., CSIRO H 3773–03, holotype, 45.1 mm SL; L. Thymichthys politus, CSIRO H 782–01, 67.3 mm SL; M. Thymichthys verrucosus (tasselled morph), CSIRO T 5, 51.3 mm SL; and N. Thymichthys verrucosus (eastern form) CSIRO H 3781– 01, 63.5 mm SL.

FIGURE 3. Skin morphology of: A. Brachionichthys australis, CSIRO H 4451–02 (x40); B. Brachionichthys hirsutus, TMH D 640 (x40); C. Brachiopsilus dianthus sp. nov., CSIRO H 4995–01, holotype (x20); D. Brachiopsilus dossenus sp. nov., NMV 29405–002, holotype (x20); E. Brachiopsilus ziebelli sp. nov., CSIRO T 1993–01, holotype (x25); F. Pezichthys amplispinus sp. nov., CSIRO H 4448–01, holotype (x50). All images orientated as a view of mid-upper body on left side (i.e. anterior part to left).