Glossogobius flavipinnis ( Aurich, 1938 )

Hoese, Douglass F., Hadiaty, Renny Kurnia & Herder, Fabian, 2015, Review of the dwarf Glossogobius lacking head pores from the Malili lakes, Sulawesi, with a discussion of the definition of the genus., Raffles Bulletin of Zoology 63, pp. 14-26 : 20-23

Glossogobius flavipinnis ( Aurich, 1938)

(English common name: Towuti Yellowfin Goby)

( Figs 5 , 6 ; Table 1 )

Stupidogobius flavipinnis Aurich, 1938: 149 (type locality Towoeti-See, Central Celebes).

Glossogobius flavipinnis . – Kottelat et al. 1993: 145 (Sulawesi, changed combination); Hoese & Allen 2009: 2 (listed)

Material examined. All from Lake Towuti , Sulawesi, Indonesia: CMK 6247, 5 males (25–36 mm SL), 2 females (40–55 mm SL), about 3 km S of Timampu, Tandjung Posombuwang ; MZB 5987 , 1 male (36 mm SL), 3 females (34-51 mm SL) about 8 km south of Timampu , between Tanjung Subalaoteh and Tandjung Petea; MZB 5988 , 1 male (32 mm SL), 2 females (44–47 mm SL), about 3 km south of Timampu , Tanjung Posombuwang , Sulawesi Selatan; MZB 21384, 3 males (33–37 mm SL), 2 females (30–31 mm SL), western Lake Towuti at cape Timbalo , – approximately 500m west of – 2°42.812’S, 121°26.885’E, F. Herder & A. Nolte, 29 Nov 2002; NSMT-P.59335, 1 female (41 mm SL), Tenemeijama; ZFMK 56309–56310 , 2 males (25–39 mm SL), alcoholic specimens, north-western Lake Towuti , about 1 km north-east of Timampu, F. Herder & A. Nolte, 7 Dec 2002; ZFMK 56311–56315 , 1 male (32 mm SL), 4 females (25–32 mm SL), western Lake Towuti south of cape Bakara, – approximately 300m west of – 2°41.331’S, 121°25.897’E, F. Herder & A. Nolte, 29 Nov 2002; ZFMK 67533-67538 , 2 males (28–39 mm SL), 4 females (31-40 mm SL), alcoholic specimens, same data as ZFMK 56311–56315 .

Diagnosis. A species of Glossogobius lacking all head pores, with mental fraenum indistinct and covered by sensory papillae; cheek naked; operculum with few embedded small scales dorsally; predorsal scaled to near eye; pectoral base scaled; prepelvic area partly scaled, naked anteriorly; second dorsal fin-rays usually I,8; anal-fin rays I,7; pectoral rays usually 15–16; predorsal scale count 17–23; pelvic fin oval, length about twice width, rays not thickened; midsides with large oval brown spots (subequal to pupil length) in juveniles; adults uniformly dark without obvious spots; gill opening wide, reaching to below or just before posterior margin of eye; first dorsal fin yellow posteriorly in life; cheek papilla lines composed of multiple rows of papillae merging into one another appearing as a uniform mass on cheek.

Description. Based on 15 males (25–38.5 mm SL), 18 females (25–57 mm SL) and 3 sex not determined 25–57 mm SL. First dorsal spines 6(30); second dorsal rays I,7 (1), I,8 (31), I,9(2); anal rays I,7(34); pectoral-fin rays 14(4), 15(24), 16(6); gill rakers on outer face of first arch 1+1+7 (3), 1+8 (1), 1+1+8 (3), 2+1+9(1); gill rakers on outer face of second arch 0+7(3), 0+8(4), segmented caudal-fin rays 16(2), 17(24); branched caudal rays 6/6(22), 7/6(3); vertebrae 10+17(12); predorsal scale count 16(1), 17(4), 18(12), 19(5), 20(7), 21(1); longitudinal scale count 27(7), 28(3), 29(62), 30(7). 31(6); transverse scale count (TRB) 8.5(5), 9(1), 9.5(25).

Head slightly compressed, depth subequal to width at posterior preopercular margin. Cheeks not bulbous. Interorbital narrow, about one half to three-quarters pupil diameter. Snout elongate, acutely pointed in dorsal view, slightly concave in side view, with distinct hump formed by ascending processes of premaxilla; often slightly convex in juveniles. No small bump below anterior nostrils. Anterior nostril at end of short tube, just above and almost in contact with upper lip. Posterior nostril a large pore just above and behind anterior nostril and separated by 1–2 posterior nostril diameters from anterior nostril. Posterior preopercular margin without spine or bony projection. Preoperculum short, distance from end of eye to upper posterior preopercular margin less than eye. Mental fraenum indistinct without fleshy projections. Mouth moderate; reaching to below or just behind anterior margin of pupil; jaws forming an angle of 15–25° with body axis, upper margin of upper jaw in line with lower half of eye. Postorbital long, distance from end of eye to posterior-most margin of operculum subequal to distance from tip of snout to middle to posterior margin of pupil. Gill opening very broad reaching to below a posterior end of eye to just behind posterior end of eye, before posterior preopercular margin. Teeth in upper jaw: outer row of teeth conical, enlarged and wide set, three-five inner rows of smaller depressible. inwardly directed teeth, an innermost row of teeth larger than those in middle rows. Teeth in lower jaw: teeth in outer row conical, slightly enlarged and wide set anteriorly to about half of dentary, two-three inner rows of smaller depressible teeth. Tongue tip bilobed. Gill rakers on outer face of first arch short and slender, becoming smaller anteriorly, shorter than filament length below each raker, longest raker near angle of arch subequal to filament length, shortest the anterior most about half filament length, anterior part of arch connected to inner face of gill cover without rakers. Rakers on inner face of first arch and other arches short and denticulate. Predorsal area scaled forward almost to eyes at sides of nape, with large triangular naked area between dorsoposterior margins of eyes. Cheek naked. Operculum with 2–4 rows of scales near dorsal margin. Pectoral base covered with small cycloid scales, two rows dorsally and three or four ventrally in about 12 vertical rows. Prepelvic fully scaled to isthmus to just before where opercula meet. Belly fully scaled, with scales on midline cycloid. Body covered mostly with large ctenoid scales, cycloid on predorsal area before a line from dorsal origin to upper pectoral fin insertion, one scale row below first dorsal fin usually cycloid, scales on pectoral base, prepelvic area and 3–4 rows on midline of belly cycloid. Body slender. First dorsal fin with second dorsal spine prolonged into a filament in males, reaching to a point between third segmented dorsal ray to beyond posterior end of second dorsal fin; normally not prolonged in females, but with a slight prolongation reaching second segmented ray in second dorsal fin in some females. Second dorsal fin subequal in height to first spine in first dorsal fin. Anal fin subequal in height to dorsal fins. Pectoral fin with pointed to acutely rounded margin, reaching to or slightly beyond anal fin origin. Pelvic disc oval, rays not thickened, length of fin 1.5–2 times greater than width; pelvic rays with few dichotomous branches, fifth ray with 4–6 terminal tips; fin reaching to or slightly behind anus.

Head pores. absent.

Sensory papillae. ( Fig. 6 ): A line of papillae along posterior margin of eye, extending between eyes, becoming two rows of papillae or each side, meeting Line 1 before eye. Line 1 (medial to nostril), continuous with interorbital lines, expanding near lip into multiple rows, curving toward midline. Line 2 (medially between nostrils) absent. Lines 5 (suborbital) and 7 composed of 4–6 rows of papillae, between eye and Line 8, without clear distinction between two lines. Line 6 (suborbital branch) probably absent or obscured by other papillae. Line 8 (VT cheek row) extending from above middle of upper lip to near posterior end of preoperculum. Below line 8, 5–8 rows of papillae representing lines 9 and 10 (VL cheek rows). Line 11 (VT row) long, short of posterior margin of preoperculum. 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 3–5 rows of papillae forming a wide band. 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 and following opercular margin a short distance ventrally. Line 22 (Lower OT) composed of a single row of papillae in a extending posteriorly upward, curving upward along opercular margin, but not meeting line 21. Line 15 (VT row) composed of a single row of papillae extending from posterior margin of eye continuous with Line 16 above operculum, extending to above posterior end of operculum. Line 17, composed of one or two rows of papillae extending from posterior margin of eye to above posterior end of operculum. Line 19 composed of 3 isolated rows extending from below Line 17 ventrally onto upper preoperculum near posterior end and a third row extending from Line 16, crossing Line 17 extending ventrally onto upper anterior part of operculum. Top of head with a line composed of a single row of papillae behind eye extending from above anterior part of Line 16 and almost meeting line from other side; Line 14 extending from transverse line posteriorly to above middle of operculum; numbers short transverse lines on each side of nape anterior to first dorsal fin. Several vertical papillae rows on belly. A single vertical line anteriorly on most body scales, becoming scattered on fewer scales posteriorly. Chin with numerous papillae arranged in oblique lines behind mental fraenum.

Colouration in alcohol. Colouration variable. Head and body uniformly light to dark brown, without distinctive markings on body or with 5 rounded dark spots on midside, spots subequal to or slightly smaller than eye size; first spot below front half of first dorsal fin, second below front of second dorsal fin, third spot below end of first dorsal fin, fourth spot on middle of caudal peduncle and fifth spots at end of caudal peduncle extending onto caudal fin base. Head with a dark brown oblique stripe (less than pupil diameter in depth) in some specimens, extending from anteroventral margin of eye to near upper lip, stripe not visible in dark specimens with dark snout. Head uniformly coloured or with two large blotches below eye, first below anterior half of eye and second extending obliquely downward and posteriorly from posterior quarter of eye; operculum with a thin dark area ventrally expanding dorsally to cover about three-quarters of operculum dorsally. Pectoral fin base uniformly coloured, light to dark brown in large adult, juveniles to about 35 mm SL with two dark areas, upper a large block mark extending on to pectoral fin dorsally and a short stripe ventrally extending slightly onto rays. Pelvic, second dorsal, anal and caudal fins usually heavily covered with melanophores appearing dark brown; pelvic fin usually lighter than other fins; first dorsal fin with dense melanophores along dorsal spines and a small patch of melanophores on anteroventral part of fin; membranes between spines otherwise white.

Life colouration. Breeding colouration of males a deep velvet-black to dark brownish black body and unpaired fins, except of the first dorsal fin. Rays in first dorsal fin black, including the prolonged second fin ray. Membranes bright yellow; base back, exceeding between the first two dorsal fin rays to mid of fin. Eye dark brown to blackish, iris back. Males in non-breeding mode with irregular brown to light blackish brown body and fins, except the yellow first dorsal fin membranes. Females with brown to dark grey body and fins; first dorsal fin membranes in females pale yellowish to grey.

Distribution and habitat. The species is only known from Lake Towuti, Sulawesi, Indonesia. In the lake, it inhabits predominantly hard substrates, from less than one to some few meters depth; deeper habitats are often dominated by soft substrates (see Rintelen et al. 2011 for a map showing the distribution of inshore habitats in the Malili Lakes). Males in breeding mood, as characterised by their velvet black colour of body and unpaired fins except for the bright yellow first dorsal fin, typically swim a few centimetres above an exposed piece of substrate, defending small territories, whereas the less conspicuous females are apparently not territorial. When scared, G. flavipinnis quickly hide between rocks or submerged wood. Glossogobius flavipinnis has been observed at all sites visited in Lake Towuti matching the habitat characteristics, and was in most cases fairly abundant.

Similarity to other species. See section under Glossogobius mahalonensis .

Remarks. A syntype ZMH 419, 1(35) was examined for us by John Paxton, however, it had dried out at some time and is now in poor condition. The description by Aurich (1938) shows no head pores and dorsal and anal ray count of I,8 and I,7 respectively agreeing with the species described here. Currently no other species is known form Lake Towuti which lacks head pores or has low dorsal and anal ray counts. Aurich (1938) indicated that none of the dorsal spines were prolonged, suggesting he only had female specimens.

In the material examined, females reach a larger size than males (57 mm SL versus 37.6mm SL, with females averaging 37.1 mm SL and males averaging 32.9 mm SL with the difference significant at p<0.05).

Figures

Fig. 5. Glossogobius flavipinnis. A, male (not preserved; © Chris Luikhaup); B, CMK 6247, male, 39 mm SL; C, CMK 6247, female, 59 mm SL; D, radiograph of CMK 6247, male; E, radiograph of CMK 6247, female.

Fig. 6. Papillae of Glossogobius flavipinnis, CMK 6247, composite of 56 mm SL female and 38 mm SL male. A, lateral view; B, dorsal view; C, ventral view.