Alabes gibbosa, Hutchins & Morrison, 2004

Hutchin, Barry & Morrison, Sue, 2004, Five New Fish Species of the Genus Alabes (Gobiesocidae: Cheilobranchinae), Records of the Australian Museum 56 (2), pp. 147-158 : 151-152

Alabes gibbosa n.sp

Fig. 3 ; Tables 1, 3

Alabes brevis (non Springer & Fraser). Hutchins, 1991: 630, fig.

Type material. HOLOTYPE: WAM P.27985-001, 67 mm SL, male, Western Australia, Carnac Island , bay on eastern side (32°07'S 115°40'E), seagrass beds, box trawl at 3–4 m, J.B.

Hutchins, 13 January 1982. PARATYPES (4 specimens, 71– 91 mm SL, from Western Australia): WAM P.32206-001, 91 mm SL, female, Safety Bay , off yacht club towards Three Sisters (32°18.5'S 115°42.3'E), seagrass bed, beam trawl, P. Chalmer, 24 September 1981 ; WAM P.32207-001, 71 mm SL (cleared and stained), Carnac Island , bay on eastern side, seagrass, boxtrawl at 2 m, J.B. Hutchins and N.O. Sinclair, 10 February 1983 ; WAM P.32208-001, 87 mm SL, Rottnest Island , Porpoise Bay (32°01'S 115°32'E), seagrass, box trawl at 3–4 m, J.B. Hutchins and S. Morrison, 09 August 1996 ; WAM P.32209-001, 84 mm SL, Cockburn Sound , Success Bank (32°05'S 115°43'E), seagrass and sand, beam trawl, Murdoch University, 5 March 1997 .

Diagnosis. The diagnostic characters of Alabes gibbosa are listed in Table 1. It differs from all other species of Alabes by a combination of its deep body (7.8–9.5 in SL), which usually exhibits a gibbous dorsal profile, relatively large gill slit (3.3–3.9 in HL), moderate-sized rudimentary pelvic fin without obvious pelvic spines or fin rays, two postocular pores, one post nasal pore above eye on each side of head, and a unique colour pattern. Alabes gibbosa is most similar to its apparent sister species, A. brevis , differing in its deeper and larger body (maximum size 91 mm SL versus 36 respectively), presence of a post nasal pore (usually absent in the latter species), more vertebrae (68–69 versus 61–62), and different coloration (males of A. gibbosa never develop a tigerlike pattern of irregular dark bars on the side of the head as found in A. brevis ).

Description. Measurements of the holotype and paratypes are presented in Table 3. Body elongate and very compressed, dorsal profile rising abruptly over level of gill opening, reaching a maximum depth about midway between snout tip and caudal fin base, maximum body depth 7.8 (7.9–9.5) in SL, maximum body width 14.8 (11.6–22.6) and width at level of gill slit 19.1 (16.7–27.3), all in SL; head slightly rounded to somewhat pointed anteriorly, a little wider than body (head width 1.6 [1.5–2.1] in HL), HL 9.8 (9.8–11.4) in SL; snout triangular in dorsal view with rounded extremity, length 5.5 (4.0–5.3) in HL; diameter of orbit 4.2 (4.2–4.9) in HL, somewhat greater than bony interorbital width (5.5 [5.2–8.9] in HL); total of six cephalic pores on each side of head, consisting of two postocular pores widely separated, one posterior nasal pore, one anterior nasal pore and two lacrymal pores; gill opening a moderately narrow slit, length 3.9 (3.3–3.9) in HL; mouth slightly inferior, upper lip projecting slightly forwards of lower lip; rear corner of mouth below anterior margin of eye or slightly behind; teeth small, conical, somewhat caninelike, 1–2 rows in upper and lower jaws; caudal fin with 9 (9–11) fin rays; bases of dorsal and anal fins long, insertion of dorsal fin usually well posterior to vertical through urogenital opening (snout to insertion 2.5 [2.2–2.7] in SL), but in one paratype, origin of fin difficult to detect and appears to be over region of urogenital opening (3.25 in SL); insertion of anal fin a short distance posterior to urogenital opening (snout to insertion 2.4 [2.0–2.8] in SL); total vertebrae could not be counted for holotype but cleared and stained paratype has a total of 68 vertebra (19 precaudal), with last epineural on 20th vertebra (radiographs of two additional paratypes indicate counts of about 19+49– 50 = 68–69).

Preserved coloration. Head and body overall pale brown, fins slightly more translucent (paratypes are similar in colour to holotype, but usually are a paler creamy brown with more translucent fins).

Live coloration (based on colour transparencies of a freshly collected specimen from Carnac Island [see Fig. 3 ], and live aquarium-maintained individuals)—ground colour apple green, somewhat translucent (internal organs slightly visible), with a sprinkling of dusky and pale spots on body, largest on midside of body following course of lateral-line (each lateral line papilla enclosed in a minute white spot, surrounded by a larger dusky spot) (see also colour plate in Hutchins, 1991); thin dark brown stripe continues from snout, through eye, to preopercular margin; snout and upper lip mostly brownish, lower lip whitish; in life, dusky spots may be very faint and white spots—especially those on rear portion of body—may be more silvery and considerably larger in size; body colour continued on to fins, with indications of faintly darker cross bars.

Distribution. Alabes gibbosa is known only from the Perth region of Western Australia, from Safety Bay to Rottnest Island.

Remarks. This species has only been collected from shallow coastal waters at depths between 2 and 4 m. It is similar to Alabes brevis (also endemic to southwestern Australia), from which it differs as described in the diagnosis above. Both occur in seagrass but A. brevis is also found in vegetation growing on shallow coastal rocky reefs.

Figures

Fig. 3. Alabes gibbosa, paratype, WAM P.32202-001, 71 mm SL, Carnac Island, Western Australia; (a) whole specimen, (b) anterior half of specimen.