Alabes springeri, Hutchins, 2006

Hutchins, Barry, 2006, Description of two new species of shore-eels (Gobiesocidae: Cheilobranchinae: Alabes) from south-eastern Australia and Norfolk Island, Memoirs of Museum Victoria 63 (1), pp. 25-28 : 27-28

Alabes springeri sp. nov.

Figure 2 ; Table 2

Alabes parvulus (non McCulloch) Springer and Fraser, 1976: 21.

Material examined. Holotype. AMS I.18497-001, 31 mm SL, Norfolk I., Emily Bay , Point Hunter (29°04'S, 167°57'E), rotenone at 1 m, C. Anderson et al., 16 Sep 1975.

Diagnosis. Alabes springeri differs from all other species of Alabes by a combination of its small gill opening (8.8 in HL), lack of a pelvic-fin rudiment, narrow interorbital space (8.8 in HL), presence of only 2 cephalic pores in the lateral line system, and the posteriorly placed origin of the dorsal-fin fold.

Description. Measurements of the holotype, the only known specimen, are presented in Table 2. Body elongate and subcylindrical, reaching a maximum depth at level of about anterior 3rd of body, then tapering posteriorly, body depth 11.1 in SL, maximum body width (= width at level of gill slit) 15.5 in SL; caudal peduncle absent (caudal fin joined to dorsal and ventral-fin folds); head small, length 7.0 in SL, a little wider than deep (head width 1.9 in HL); snout short, rather rounded to slightly truncate anteriorly in dorsal view, length 3.1 in HL; nostrils small but obvious, anterior one tubular, posterior one with low raised rim; eye moderate in size, with prominent clear cornea, diameter of orbit 3.7 in HL, noticeably greater than bony interorbital width (8.8 in HL).

Skin smooth and scaleless, normally covered with a thick mucus layer; lateral line sensory system consists of minute papillae (latter very difficult to detect); cephalic pores 2 on each side of head, 1 POP and 1 ANP. Gill opening a narrow slit, located on ventral surface of head, width 8.8 in HL; gills and branchiostegals not examined; mouth subterminal, upper jaw projecting over lower jaw, upper and lower lips rather narrow, rear corner of mouth not reaching anterior margin of eye (pigmented area); teeth incisorform, 1 row in upper and lower jaws; palatine and vomerine teeth absent. Dorsal and anal-fin folds resemble low fins, but lacking both fin rays and underlying pterygiophores, continuous with caudal fin; caudal fin without visible fin rays, although there is evidence that the posterior portion of the specimen was damaged at some time (portion of caudal and anal-fin folds lost, and some vertebral elements also protruding through side of body); bases of dorsal and anal-fin folds relatively short, insertion of dorsal-fin fold well behind vertical through urogenital opening (snout to insertion 1.8, snout to urogenital opening 2.6, both in SL), snout to insertion of anal-fin fold 1.4 in SL; urogenital opening with small papilla. Total vertebrae 71 (from Springer and Fraser, 1976), with last epipleural on 20th vertebra.

Colour in alcohol. Head and body overall pale brown, fins more translucent. Springer and Fraser, 1976 illustrated some partial cross banding on the abdominal region, triangular in shape (see fig. 2), but this has since faded.

Colour in life. Unknown

Distribution. Alabes springeri is known only from the type locality (Norfolk I.).

Remarks. This species inhabits shallow coastal waters (single specimen taken from a depth of 1 m). It is most similar to Alabes parvula from eastern Australia, differing in the exceptionally short base of the dorsal-fin fold, different shape of the dark bars on the side of the abdomen (triangular-shaped versus more squarish in A. parvula ), and the expanded shape of the buccal region (not expanded in A. parvula ). Like other members of the Alabes parvula complex ( A. parvula , A. occidentalis , and A. hoesei ), it lacks a pelvic fin rudiment, has a very small gill slit, its body probably is transparent in life (at least posterior to urogenital opening), and its maximum size is less than 50 mm TL (see Table 1 in Hutchins and Morrison, 2004). This species is named springeri in honour of V.G. Springer (USNM) who, with T. Fraser in 1976, first reported the apparent uniqueness of the Norfolk Island specimen. (NB. registration number AMS I.18470-002 was inadvertently assigned to this specimen by Springer and Fraser, 1973: 21, but that number belongs to one of the paratypes of Alabes hoesei which was described in the same paper).

Figures

Figure 2. Alabes springeri, hototype, AMS I.18497-001, 31 mm SL, Norfolk I., Emily Bay, Point Hunter (illustration courtesy of Victor Springer, USNM).