Actinopterygii (Gigaclass) > Actinopteri (Class) > Teleostei (Subclass) > Gobiiformes (Order) > Gobioidei (Suborder) > Gobiidae (Family) > Gobiinae (Subfamily) > Psammogobius (Genus)

Gobie des pentes sablonneuses, Sandslope Goby,

Description
Dorsal spines (total): 6+1; Dorsal soft rays (total): 9-10 (usually: 9); Anal spines: 1; Anal soft rays: 8-9 (usually: 9); Pectoral fin rays: 16-19 (usually: 17); Pelvic fin rays: I, 5; Caudal fin: 12 branched and 17 segmented rays and 6 (4-6) unsegmented (procurrent) rays dorsally and 5 (4-6) rays ventrally; Gill rakers poorly developed: 0 + 6; Total vertebrae: 27. Longitudinal scales: 26. Third dorsal-fin spine sometimes with short filamentous extension; Anal fin elements all segmented; Dorsal (and anal) fin rays branched; Pectoral fin rays branched except uppermost and lowermost; Pelvic fin rays ray branched twice except fifth ray with three branch points; Pelvic fin membrane fully developed, frenum relatively low and weakly developed. Scales ctenoid on body, except cycloid anteroventrally on breast, belly, and prepelvic area; Head and nape scaled. Max. length: 3.0 cm TL. Depth range: 10 - 20 m.

Color
Generally light gray to brilliant white with three broad brown saddles on dorsal half of body, first below posterior portion of first dorsal fin, second below middle of second dorsal fin, and third at middle of caudal peduncle, anteriormost saddle darker and wider than others; Horizontal row of 5–6 widely spaced, irregular dark-brown spots immediately below dorsal saddles and sometimes connected to them; Cheek and operculum mainly mottled brown with stellate melanophores, also a zone with same markings arching above pectoral-fin base and connecting with first dorsal saddle; 2-3 brilliant white spots on side of snout and on cheek; Eye with greenish-to-red pupil and reddish brown iris, becoming pale grey dorsally and sometimes with a pair of short bars on dorsal scleral surface; First dorsal fin mainly brownish due to numerous expandable melanophores, fin darkest posteriorly where merges with first saddle of dorsal half of body, sometimes a small blackish spot near tips of fifth and sixth spines; Second dorsal fin mainly plain translucent with a few scattered white dots; Anal and pelvic fins translucent with numerous melanophores; Pectoral fin with brilliant white base, white extending as elongate streak onto rays of middle portion of fin, also a blackish spot near base of upper rays and elongate blackish streak on lower edge of fin.

Etymology
Psammogobius: from Greek, psammos = sand +  from Latin, gobius = gudgeon. In reference to occurrence of Psammogobius knysnaensis on the "sand banks" of tidal rivers.
pisinnus: from Latin, pisinnus = small or little. In reference to to "exceptionally small" maximum size (<20 mm SL) compared to congeners (70-80 mm SL).
Original description: Psammogobius pisinnus Allen, 2017 - Type locality: Papua New Guinea, West New Britain Province, 1 km SW of Baronga Village, Sharon’s Island, 6°15.235’ S, 150°27.429’ E, 14-18 m, clove oil and hand net, G. Allen & A. Joseph, 3 February 2017.

Distribution
New Britain (Papua New Guinea), Great Barrier Reef (Australia) and New Caledonia.

Biology
Muddy bottom with algae in a bay. Hide in a burrow.