Alabes occidentalis, 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 : 153-154

Alabes occidentalis n.sp.

Fig. 4 ; Tables 1, 5

Alabes parvulus (non McCulloch). Springer & Fraser, 1976: 19, fig. 12 (in part); Hutchins, 1991: 630, fig.; Hutchins, 1994: 314 (in part).

Type material. HOLOTYPE: WAM P.25465-001, 36 mm SL, male, Western Australia, Safety Bay, Seal Island (32°17.4'S 115°41.1'E), beam trawl in seagrass, J. Scott, 3 October 1975 . PARATYPES (28 specimens, 17–40 mm SL, from Western Australia) : AMS I.42137-001, 37 mm SL, male, collected with WAM P.28267-001 (see below); WAM P.25465-004, 3 specimens, 22–40 mm SL, collected with holotype ; WAM P.25805-002, 26 mm SL, near Garden Island, just west of Five Fathom Bank (32°17'S 115°31'E), trawled at 37 m, N. Sarti and R. George , 29 June 1977 ; WAM P.27952-012, 5 specimens, 17–31 mm SL, Jurien Bay, south side of Boullanger Island (30°18'S 115°00'E), seagrass bed, box trawl at 1 m, J.B. Hutchins et al., 11 April 1983 ; WAM P.28267-001, 5 specimens, 34–38 mm SL, Carnac Island , east of island (32°07'S 115°40'E), seagrass, box trawl at 3–4 m, J.B. Hutchins et al., 10 February 1984 ; WAM P.28280-001, 6 specimens, 27–35 mm SL (2 cleared and stained), Israelite Bay, near Point Dempster (33°37'S 123°53'E), seagrass, box trawl at 0.5–2.0 m, J.B. Hutchins, 1 April 1984 ; WAM P.28291-001, 3 specimens, 27–30 mm SL, Great Australian Bight, Twilight Cove , just off beach (32°16'S 126°02'E), seagrass, box trawl at 0.2–1 m, J.B. Hutchins, 10 April 1984 ; WAM P.30384-002, 4 specimens, 29–39 mm SL, Rottnest Island, Porpoise Bay (32°01'S 115°32'E), seagrass, box trawl at 2–4 m, J.B. Hutchins, 21 November 1991 .

Diagnosis. The diagnostic characters of Alabes occidentalis are listed in Table 1. It differs from all other species of Alabes by a combination of its elongate transparent body (depth 9.1–15.9 in SL), very small gill slit (5.4–17.5 in HL), no rudimentary pelvic fin, single postocular pore, anterior nasal pore present but posterior nasal pore absent, no lacrymal pores and unique colour pattern in adult male (tiger-like brownish orange bars anteriorly on side of body, darker ventrally). Alabes occidentalis is very similar to A. parvula , differing in the shape of the posterior portion of the gut (shorter and more rounded in A. parvula when viewed laterally in freshly caught material), lack of lacrymal pores (usually present in A. parvula ) and in coloration of the adult male (see Remarks below).

Description. Measurements of the holotype and paratypes are presented in Table 5. Body elongate, more subcylindrical in adult male, maximum body depth 9.1 (9.9–15.9), maximum body width 16.7 (15.5–22.4) and body width at level of gill slit 16.7 (15.5–20.5), all in SL; head pointed, compressed, length 8.3 (7.8–10.0) in SL; snout rounded to slightly truncate in dorsal view, length 3.6 (3.1–4.0) in HL; diameter of orbit 3.5 (3.0–4.1) in HL, prominently larger than bony interorbital width (5.6 [6.5–10.4] in HL); total of two cephalic pores on each side of head, consisting of one postocular pore, one anterior nasal pore (no clearly defined lacrymal pores could be found); gill opening a short, narrow slit, width 8.2 (5.4–17.5) in HL; mouth inferior, upper lip projecting slightly forward of lower lip; rear corner of mouth below anterior margin of eye or slightly behind; teeth small but caninelike, 1–2 rows in upper and lower jaws; caudal fin apparently deformed in holotype, with only 1 or 2 rays (paratypes with 4–6 fin rays), continuous with dorsal and anal fins; bases of dorsal and anal fins long, insertion of dorsal fin over or slightly behind vertical through urogenital opening, snout to insertion 2.6 [2.7–3.1] in SL; insertion of anal fin about half way between urogenital opening and caudal fin (snout to insertion 1.7 [1.6–1.8] in SL); total vertebrae 63–69, precaudal 15–17, last epineural on 16–17th vertebra.

Preserved coloration (in alcohol). Head and body pale brown overall, fins more translucent (see also Remarks below).

Live coloration (based on colour transparencies of freshly collected material, Fig. 4 ): male—body mostly translucent to transparent, with organs visible through skin, although abdominal portion becoming more milky coloured anteriorly with a tiger-like pattern of brownish orange bars, distinctly darker ventrally, bars extending less than half distance to urogenital opening (see Springer & Fraser, 1976: fig. 12d,e [as Alabes parvulus ]); head brown, consisting of dark brown blotches below and behind eye; silvery white spot at rear of body (not always visible); dorsal fin with dusky blotches along length, fading posteriorly (usually no dusky bars on dorsal surface of back); female—body transparent, with all organs visible through skin (see Hutchins, 1991: 631 [as Alabes parvulus ]); no tiger-like pattern of bars anteriorly although numerous short, darkbrown bars present across ventral and dorsal surfaces of abdomen (see Springer & Fraser, 1976: fig. 12a–c); head mostly transparent with several short, dark bars and spots below eye; dusky blotches on dorsal fin and silvery white spot on rear of body as in male.

Distribution. Alabes occidentalis ranges from the Houtman Abrolhos in Western Australia to Twilight Cove in the Great Australian Bight. Specimens from South Australia and Tasmania identified as Alabes parvula may also prove to be this species, but freshly caught material has not yet been examined.

Remarks. Alabes occidentalis , unlike its apparent close relative, A. parvula , has only been taken from seagrass beds (the latter has also been found in reef and algal areas, particularly intertidal rock pools). The two species are so similar that they were initially treated by Springer & Fraser (1976) as belonging to one species, A. parvula . The figures of that species (Springer & Fraser, 1976: fig. 12) were based wholly on Western Australian material, and are thus illustrative of A. occidentalis and not A. parvula . Although the female colour pattern of both species is similar, that of the male differs considerably between species. The male of A. parvula , in comparison to the colour description of A. occidentalis provided above, is distinguished by the following: anterior portion of body with a tiger-like pattern of irregular reddish-brown bars, bars continued onto head and break into spots, and also continue posteriorly, and break into spots; abdominal area bright orange to yellow with four large bluish black circular to rectangular blotches, arranged in a horizontal line along lower side, extending over half distance to urogenital opening. Other differences are described in the Diagnosis above. Alabes hoesei is also very similar to A. occidentalis but is easily distinguished by the higher number of cephalic sensory pores (Table 1). This species is named occidentalis because of its western distribution.

Figures

Fig. 4. Alabes occidentalis paratype, female, WAM P.28280-001, 35 mm SL, Israelite Bay, Western Australia: (a) whole specimen; (b) anterior half of specimen. Paratype, male, WAM P.30384-002, 38 mm SL, Rottnest Island, Western Australia: (c) whole specimen; (d) anterior half of specimen.