Desert Goby, Chlamydogobius eremius (Zietz 1896)

Endemic to the western and southern parts of the Lake Eyre drainage basin, South Australia, from north of the Flinders Ranges to the Neales River.

Desert gobies inhabit both permanent and ephemeral water bodies, including spring-fed pools and bores, and desert streams. They live on the bottom, preferring shaded areas around plants or rocks. During the day, they mostly shelter under rocks and in crevices.

Individuals can tolerate extreme variations in temperature (5-41°C), pH, salinity and dissolved oxygen levels.

Dorsal fin IV-VI +  I, 6-8; Anal fin I, 5-8; Pectoral fin 12-15; Caudal fin (segmented rays) 16-17 (branched rays) 14-16; Pelvic fin I, 5; Vertebrae 10-11 + 16-18 = 27-29; Gill rakers 2-3 +5-10 = 7-13; Horizontal scale rows 13-19; midlateral scales 32-57 (usually 40-51).

Body cylindrical anteriorly, compressed posteriorly. Head short, somewhat rounded, length 2.8-3.5 in SL. Snout rounded to rather flattened. Anterior nostril in short tube, placed on edge of preorbital, tube oriented down and forward, preorbital sometimes curved forward slightly to accommodate nostril. Posterior nostril small, oval, placed halfway between front centre margin of eye and edge of preorbital.

Eyes lateral, high on head, top usually part of dorsal profile, 2.6-5.6 in HL. Interorbital broad, flat to very slightly convex; top of head, from rear of interorbital space up to snout tip, with scattering of very fine villi. 
Lips usually fleshy, smooth, lower lip free at sides, fused across front.

Mouth terminal to subterminal, slightly oblique, upper jaw slightly overhanging lower jaw; generally reaching to below mid-eye in males and front half of eye in females; teeth of upper jaw in 4-6 rows, outermost usually larger than others, stout and curved or almost upright, others slightly smaller; teeth of lower jaw in 5-6 rows; teeth not differing much between males and females; tongue thick and fleshy, usually blunt to rounded. Gill opening restricted to pectoral base; inner edge of shoulder girdle either smooth and fleshy, or hard-edged.

Ctenoid scales on side of body at least as scattered scales on caudal peduncle and patch behind pectoral fin. Predorsal scales usually absent, when present, midline of nape naked with scales extending forward at sides to above opercle, or 0-10 small scales immediately before first dorsal fin or scattered unevenly over nape; operculum generally naked, occasionally a few dorsally; cheek naked; pectoral fin base naked; prepelvic area usually naked; belly sometimes with naked mid-line, otherwise covered with cycloid scales and isolated patch under pelvics of weakly ctenoid scales.  Lateral line absent; lateral scale series 33-57. Head pores absent.

Two dorsal fins, first low, rounded, spines not reaching second dorsal when depressed; second dorsal and anal fins low, last rays barely reaching caudal fin in largest males. Pectoral fin broad, rounded. Pelvic fins united into complete disc, small, rounded to oval, occasionally reaching half distance to anus. Caudal fin oval to rounded or nearly truncate.

Head and body greyish-brown with 7-8 brown clearly defined square saddles or highly marbled patches across the back, saddles not extending past the mid-side, replaced below by marbled blotches, square blotches or irregular spots merging ventrally with background; caudal fin base with 1-3 dark brown to greyish brown spots, sometimes forming Y-shape or vertical bar, with yellowish brown background surrounding spots; silvery white peritoneum usually evident through body wall.

Top and sides of head marbled and spotted with brown, sometimes 1-2 dark brown bars from eye to upper lip; lips bluish grey; iris deep golden, with dark brown margin.

First dorsal fin greyish brown with deep yellowish submarginal band, above narrow blue line that widens posteriorly to form bright blue spot; second dorsal fin with pale greyish brown membrane, dark brown fin rays and darker brown blotches along base.

Caudal fin pale greyish brown with irregular, vertically oriented rows of fine brown spots. Pectoral fin pale greyish brown to hyaline, fin base with brown blotch on upper half.

Breeding males with diffuse markings; first dorsal fin very dark grey, with vivid yellow and blue; second dorsal and anal fins dark grey to blackish with broad bright white margin; fins speckled basally with blue; caudal fin dark grey with narrow dull whitish fin margin.

Gomon, M.F. & Bray, D.J. 2023

Atlas of Living Australia