Glossogobius robertsi, Hoese, Douglass F. & Allen, Gerald R., 2009

Hoese, Douglass F. & Allen, Gerald R., 2009, Description of three new species of Glossogobius from Australia and New Guinea, Zootaxa 1981, pp. 1-14 : 3-6

Glossogobius robertsi , sp. nov.

Figures 1–4 , Tables 1–3

Glossogobius giuris . — Roberts, 1978: 61 (Fly River, in part, figures b and c). Glossogobius sp. 7. — Allen, 1991: 185, pl. 15, fig. 7 ( Papua New Guinea).

Holotype. WAM P.27803–009, 132 mm SL male. Ok Tedi River system tributary 10 km S. of Tabubil on Kiunga Rd. (5°21'S, 141°17'E), G. Allen and J. Paska, 17 September, 1982.

Paratypes (all from Fly River System, Papua New Guinea). AMNH 13788, 2(92–130), Upper Fly River, Archibold Expedition, Rand & Tate, 1936; AMS I.27510–001[ex WAM P.27803–006], 2(51–90), collected with holotype; NTM S.14819–002, 3(49–91), Ok Mani, Fly River, Ok Tedi Mining, 31 May 1983; USNM 217239, 1(62), small tributaries and mainstream, 1–2 km upstream from mouth of Elevala River, 856 km upriver from Toro Pass (6°03'S, 141°24'E), T. Roberts, 26 October, 1975; USNM 217242, 2(28–37), 7 km NNE of Ningerum, approximately 900 km upriver from Toro Pass (5°37'S, 141°10'E), T. Roberts, 4 November, 1975; WAM P.27803–006, 9 (37–106), taken with holotype; WAM P.28143–004, 1(91), Ok Mani River, 5 km E of Tabubil (5°16'S, 141°11'E), G. Allen & D. Balloch, 9 September, 1983.

Non-type Material. NTM S.14681, 1(52), Ajkwa River, Papua.

Diagnosis: A species of Glossogobius with mental frenum formed by short lateral lobes; cheek and operculum naked; predorsal scaled to near eye; pectoral base and prepelvic area only partly scaled; second dorsal fin-rays I,9-10; anal-fin rays I,8; pectoral rays usually 19; predorsal scale count 16-22; pelvic fin oval, slightly thickened, length subequal to or slightly longer than wide; midsides with large brown spots (much larger than eye length); no black spot posteriorly on first dorsal fin; cheek papilla lines composed of single row of papillae; papilla line 6 absent and vertebrae usually 12+16.

Description: Based on 21 specimens 28 – 132 mm SL. First dorsal spines 6(19*); gill rakers on outer face of first arch 0+1+5(2), 0+1+6(1), 1+1+5(1), 1+1+6(3), 1+1+7(5), 2+1+6(1), 2+1+7(1); segmented caudal-fin rays 17(19*); branched caudal rays 7/6(2), 7/7(9), 7/8(3), 8/7(2*); vertebrae 11+17(1), 12+16(8*); predorsal scale count 16(1), 17(2), 18(2), 19(2), 20(3), 21(1), 22(2*); longitudinal scale count 30(1), 31(2), 32(7), 33(6*), 34(2); transverse scale count (TRB) 9.5(10*), 10.5(4). Second dorsal-fin rays I,9–10; anal-fin rays I,8; pectoral-fin rays 18–19, usually 19 (see Tables 1–3 ).

Head depressed, 28–33% SL in specimens less than 80 mm SL, 32–35% SL in specimens greater than 80 mm SL. Cheeks bulbous. Interorbital narrow, much less than eye length. Snout short, rounded in dorsal view, slightly convex in side view; 6–10% SL in specimens less than 80 mm SL, 10–11% SL in specimens greater than 80 mm SL. Eye about 1.5 in snout, 6–8% SL in specimens less than 80 mm SL, 5–6% SL in specimens greater than 80 mm SL. Small bump below anterior nostrils present. Anterior nostril at end of short tube, well above upper lip (2–4 nostril diameters above). Posterior nostril pore midway between upper lip and eye and 2–3 nostril diameters from anterior nostril. Posterior preopercular margin without spine. Preoperculum short, distance from end of eye to upper posterior preopercular margin subequal to eye in specimens less than 60 mm SL to twice eye in specimens over 100 mm SL. Mental fraenum with posterior margin concave, short lateral lobes fused to chin. Mouth moderate, reaching to below or just before mideye; jaws forming an angle of 35–40° with body axis, upper margin of upper jaw in line with lower margin of pupil to midpupil. Upper jaw 11.5–12.8 % SL in specimens less than 60 mm SL, 12.5–14.8% SL in specimens greater than 60 mm SL. Postorbital long, subequal to or slightly longer than distance from tip of snout to posterior margin of eye. Gill opening reaching to below a point about 1 pupil diameter before posterior preopercular margin. Teeth in upper jaw: outer row of teeth conical, slightly enlarged and wideset, three inner rows of smaller depressible, inwardly directed teeth, innermost row larger than middle row. Teeth in lower jaw: teeth in outer row conical, slightly enlarged and wideset anteriorly, one inner row of smaller depressible. Tongue tip bilobed. Gill rakers on outer face of first arch short and broad; about one-fifth filament length. Rakers on inner face of first arch and other arches short and denticulate. Predorsal area scaled forward to just behind, with a naked patch from eye to midway to posterior preopercular margin. Cheek naked. Operculum naked. Pectoral base with few scales, one row dorsally and three ventrally, often naked in specimens less than 40 mm SL. Prepelvic area sparsely scaled, with minute embedded scales just before pelvic origin, covering less than half the area, sometimes naked in specimens less than 40 mm SL. Belly fully scaled. Body covered mostly with large ctenoid scales, cycloid on predorsal area (ctenoid in young), pectoral base, prepelvic area and midline of belly. First dorsal fin low, with rounded margin, spines 4–6 extending beyond other spines when fin depressed. Second dorsal fin subequal in height to first dorsal fin. Anal fin subequal in height to dorsal fins. Pectoral fin with pointed to acutely rounded margin, reaching to or just beyond anus. Pelvic disc rounded, rays slightly thickened, length of fin subequal to or slightly greater than width; fifth ray with 10–20 terminal tips; fin reaching about a pupil diameter short of anus in specimens less than 60 mm SL to about half way to anus in larger specimens.

Head pores: nasal pore usually in front of posterior nostril and above anterior nostril (above posterior nostril on one side of one specimen); anterior interorbital pore present; posterior interorbital pore present; postorbital pore behind eye present; infraorbital pore below postorbital present; lateral canal pore above preoperculum present; lateral canal pore above posterior preopercular margin absent; terminal lateral canal pore above posterior preoperculum present; short tube above operculum, with pore at each end present; 3 preopercular pores, upper in line with lower margin of eye, widely separated from lower 2.

Sensory Papillae: ( Figure 2 ). Line 1 (before nasal pore) short and composed of single row of papillae. Line 2 (medially between nasal pores) composed of single row of papillae, beginning well above posterior nostril, continuous across snout or with gap on midline of snout. Line 5 (suborbital) composed of single row of papillae, line curved ventrally anteriorly meeting line 7 below anterior margin of eye. Line 6 (suborbital branch) absent. Lines 7, 9, 10 (VL cheek rows) each composed of single row of papillae. Line 8 and 11 (VT row) short, not reaching posterior preopercular margin. Line 12 (Outer POP-mandibular) composed of single row of papillae, with large gap adjacent to end of jaws. Line 13 (Inner POP-mandibular) composed of double row of papillae at sides of chin, a single row of papillae posteriorly. Line 20 (OP VT) opercular segment composed of single row well separated from oblique row just above posterior preopercular margin, row extends ventrally curving forward on to branchiostegal membranes. Line 21 (Upper OT) composed of a single row of papillae, curved downward posteriorly. Line 22 (Lower OT) composed of a single row of papillae in a short segment extending posteriorly upward, not meeting line 21. Several vertical papillae rows on belly. A single curved line anteriorly on most body scales (often obscure dorsally and posteriorly. Chin papillae arranged in distinct TL lines behind mental fraenum following contour of fraenum.

Coloration in alcohol: Head and body brown. Eye with one or two short cross bands on dorsal margin. Cheek with small scattered dark brown spots; a broad stripe (width about equal to pupil diameter) from anteroventral margin of eye to upper lip; chin dark brown in both sexes; branchiostegal membranes light brown. Body scales densely pigmented with brown spots, not edged in dark brown; a small black spot (less than half pupil diameter) behind eye; a second spot of similar size on nape just above anterior part of operculum. Back with saddles above and often connected to midside spots; midside of body with 5 very large round spots (subequal to eye size or slightly larger); first spot below middle of first dorsal fin, usually connected to dark saddle below dorsal fin, forming an oblique band, second below second dorsal origin and just behind (also sometimes connected to dorsal saddle to form an oblique band, third below posterior end of second dorsal fin (also sometimes connected to dorsal saddle forming an oblique band), fourth on middle of caudal peduncle fin (rarely connected to dorsal saddle forming an oblique band); and fifth on posterior end of caudal peduncle, without a saddle dorsally. First dorsal fin without large black spots posteriorly. A dark brown spot or short horizontal bar dorsally on pectoral fin base, often with brown mottling on upper half of pectoral base; sometimes with a short horizontal bar ventrally on pectoral fin base.

First dorsal fin grey to brown, with distinct bands formed by dark brown spots on fin; usually a broad dark brown or black stripe at base of fin. Second dorsal fin with small brown spots forming 3–4 longitudinal rows basally, followed by a clear or pale gray band and dark gray band at distal tip. Caudal fin with 8–11 broad wavy bands, not extending onto lowermost 5–6 segmented caudal-fin rays, but extending onto all but upper one or two segmented caudal-fin rays. Anal fin gray to brown, with no mottling or banding. Pelvic fin brown to black, often light brown in females less than 50 mm SL. Pectoral fin uniform gray to brown and no spotting.

Distribution: Glossogobius robertsi is known from several locations from the Upper Fly River system, usually in creeks above 500 m elevation. Also possibly known from the Ajkwa River in the Timika region of Papua Province ( Indonesia), which lies approximately 500 km west of the Upper Fly (see Remarks).

Similarity to other species: Glossogobius robertsi is easily separated from other species ( Glossogobius celebius , G. t o r re n t i s, G. coatesi and other species described as new herein) with a developed lobed mental frenum by the large spots on the side of the body, the reduced scale coverage on the pectoral base and prepelvic area, short round pelvic fin and absence of opercular scales.

Remarks: A single specimen 52 mm female (NTM S.14681) from the Ajkwa River in Papua is tentatively identified as the current species ( Figure 4 ). The specimen agrees in coloration, particularly the large spots on the side with G. robertsi , but differs in having second dorsal-fin rays I,8 and anal-fin rays I,7, lower counts than in other specimens.

Etymology: Named for Tyson Roberts who collected most of the type material.

Figures

FIGURE 1. Holotype of Glossogobius robertsi, WAM P. 27803 – 009, 132 mm SL.

FIGURE 2. Sensory papilla pattern of Glossogobius robertsi based on paratype, USNM 217239, 62 mm SL.

FIGURE 3. Mental frenum of Glossogobius robertsi based on paratype, AMS I. 27510 – 001, 90 mm SL.

FIGURE 4. Glossogobius robertsi NTM S. 14681, 52 mm SL from Ajkwa River, Papua.