Glossogobius macrocephalus, Hoese, Douglass F. & Allen, Gerald R., 2015

Hoese, Douglass F. & Allen, Gerald R., 2015, Descriptions of three new species of Glossogobius (Teleostei: Gobiidae) from New Guinea, Zootaxa 3986 (2), pp. 201-216 : 203-207

Glossogobius macrocephalus n. sp.

Figs. 2 a, 3, 4, Tables 1–6 Bighead Goby

Glossogobius sp. 13. — Allen, 1991: 187, pl. 15, fig. 3 ( Papua New Guinea).

Holotype. WAM P.26972–004, 73 mm SL male, creek 4 km E of Lake Tebera (6°45'S, 144°39'E), 24 Sept., 1980, G. Allen & B. Parkinson.

Paratypes. WAM P.26972–003, 2(59–66), taken with holotype; WAM P.30383–003, 2(23–112), small tributary creek and Lake Tebera, 19 Oct. 1991, G. Allen; AMS I.46502–001, 1(86), same data as WAM P.30383– 0 0 3.

Diagnosis. Preoperculum without a spine, but with small flat projection adjacent to lower preopercular pore. Mental fraenum low with short lateral lobes. Mouth small; reaching to below anterior margin of eyes; jaws forming an angle of 40–50° with body axis; upper margin of upper jaw in line with lower margin of pupil. Head robust and large, cheeks slightly bulbose and tapering. Interorbital narrow, less than eye length. Predorsal area scaled forward to just behind eye, with a narrow naked patch between and behind eyes. Cheek naked. Operculum naked. Pectoral base with 1–3 vertical rows of scales. Prepelvic area about three-quarters scaled in 7–8 rows, naked anteriorly. Belly largely scaled, with a very small naked patch behind pelvic insertion. First dorsal fin spine 3–5 extending beyond other spines when fin depressed. First dorsal fin with black spot posteriorly on membrane surrounding sixth dorsal spine, spot faint in female. Pelvic fin thin, length much greater than width, reaching anus. Second dorsal rays I,9–10; anal rays I,8; pectoral rays 17–18; longitudinal scale count 30–31; predorsal scale count 15–18; transverse scale count (TRB) 9.5–10.5; gill rakers on outer face of first arch 1+1+6–8=8–10; lower gill rakers on outer face of second arch 6–7; branched caudal rays 14–15; vertebrae 12+16=28.

Papillae: Line 1 (before nasal pore) composed of 2 rows of papillae (sometimes incomplete). Line 2 (between nasal pores) composed of a single row of papillae usually continuous across snout. Line 5 (suborbital) composed of single row of papillae (double in one specimens on one side of head below infraorbital pore), joining line 7 below posterior nostril. Line 6 (suborbital branch) absent. Lines 7, 9, 10 (LL cheek rows) composed of a single row of papillae, but irregular anteriorly appearing double, reaching to posterior preopercular margin. Lines 8 and 11 (LT row) reaching just short of posterior preopercular margin. Line 12 (Outer POP–mandibular) composed of single row of papillae, appearing double along lips, without gap at end of lips. Line 13 (Inner POP–mandibular) composed of 2–3 rows of papillae. Line 20 (opercular VT row) composed of single row of papillae dorsally, and double ventrally. Line 21 (Upper opercular OT) composed of single row of papillae, strongly curved ventrally meeting or almost meeting line 22. Line 22 (Lower opercular OT) composed of single row of papillae, curving upward along posterior opercular margin. Several vertical papillae rows on belly. A single curved line anteriorly on most body scales (often obscure dorsally and posteriorly); chin with an oval patch of papillae behind mental fraenum, with a notch posteromedially without papillae.

Description. Based on 6 specimens 23–112 mm SL, data not taken on smallest. Count of holotype indicated with an asterisk, where a range of counts exists. First dorsal spines 6(5*); gill rakers on outer face of first arch 0+1+7(1), 1+1+6(1). 1+1+7(2), 1+1+8(1); segmented caudal rays 9/8(5*); branched caudal rays 7/7 (2), 7/8(1), 8/ 7(2*); vertebrae 12+16(3*). Counts of other meristic characters given in Tables 1–6.

Species Locality Second dorsal fin

I, 7 I, 8 I, 9 I,10 G. macrocephalus - - 2 3* G. multipapillus Safia 1 27 - - Popondetta 1 22* 4 - Kokoda - 12 - - G. sentaniensis - 27* - - Species Locality Analfin

I. 6 I, 7 I, 8 I,9 G. macrocephalus - - 5* - G. multipapillus Safia 1 28 1 - Popondetta - 25* 2 - Kokoda 1 11 - G. sentaniensis - - 27* 2 Species Locality Pectoral ray counts

16 17 18 19 20 G. macrocephalus - 4* 1 - - G. multipapillus Safia 8 21 1 - - Popondetta - 1 19* 6 - Kokoda - 2 9 1 - G. sentaniensis - - 3 20* 5 Species Locality Predorsal scales

12 13 14 15 16 17 18 25 26 27 28 29 30 31 G. macrocephalus - - - 1 1 2* 1 - - - - - - - G. multipapillus Safia 4 3 6 2 - - - - - - - - - - Popondetta 1 3 5 2 - - - - - - - - - - Kokoda 1 4 3 4 1 - - - - - - - - - G. sentaniensis - - - - - - - 2 - 3 8* 2 5 2 Species Locality Longitudinal Scale Count

25 26 27 28 29 30 31 32 33 34 35 G. macrocephalus - - - - 1 3* 1 - - - - G. multipapillus Safia 1 5 6 - - - - - - - Popondetta - 3 10 2 - - - - - - - Kokoda 1 3 7 1 - - - - - - - G. sentaniensis - - - - - - 4 6 5 3* 1 TransverseScaleCount

Species Locality 8.5 9.5 10.5 11.5 12.5 G. macrocephalus - 3* 2 - - G. multipapillus Safia 15 - - - - Popondetta 7* 3 - - - Kokoda - - - - - G. sentaniensis - - - 13* 9 Head large, slightly depressed, length 32.9–34.9% SL, depth 17.3–18.3% SL, width 18.7–21.2% SL. Snout rounded in dorsal view, straight in side view; 9.4–11.7% SL. Eye about 1.2–1.5 in snout, 6.2–8% SL (6.2–7% SL in specimens over 70 mm SL). Small bump below anterior nostril present. Anterior nostril at end of short tube, 1 nostril diameter above upper lip. Posterior nostril a pore, midway between eye and upper lip, 3–4 nostril diameters from eye and 1–2 from anterior nostril. Preoperculum short, distance from end of eye to upper posterior preopercular margin slightly less than eye length. Postorbital long, subequal to distance from tip of snout to posterior half of eye. Gill opening reaching to below posterior preopercular margin. Teeth in upper jaw: outer row of teeth conical, slightly enlarged and wideset, 3 inner rows of smaller depressible, inwardly directed teeth, innermost row larger than middle rows. Teeth in lower jaw: teeth in outer row conical, slightly enlarged and wideset anteriorly, 2 inner rows of smaller depressible teeth, teeth in innermost row larger than teeth in middle row. Tongue tip bilobed. Gill rakers on outer face of first arch short and broad, one–third to one–quarter filament length. Rakers on inner face of first arch and other arches short and denticulate. Body covered mostly with large ctenoid scales, cycloid predorsal area, pectoral base, prepelvic area and midline of belly. First dorsal fin round to triangular shaped. Second dorsal fin subequal in height to first dorsal fin. Anal fin slightly lower than dorsal fins. Pectoral fin with pointed margin, reaching to above a point just before anus to anal origin. Pelvic disc thin, length greater than width, reaching about ¾ of way to anus or just reaching anus; fifth ray with 10 terminal tips of rays at posterior margin of fin in holotype.

Head pores: nasal pore before and medial posterior nostril; 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 anterior operculum present; short tube above operculum, with pore at each end present or represented by open trench; 3 preopercular pores, upper in line with lower margin of eye; widely separated from lower 2.

Coloration in alcohol: Head and body brown. A dark brown bar from anteroventral margin of eye extending to upper lip; posterior end of lips whitish; an oval brown blotch at posteroventral margin of eye, followed by a small irregularly shaped dark brown blotch; an irregular dark brown blotch on cheek below anterior half of eye; sometimes a series of small dark brown spots forming a horizontal line on cheek; chin pale to faint grey, lighter than top of head; operculum with dark brown mottling. Pectoral base with an upper dark brown spot followed by a curved brown bar on bases of pectoral rays; a second dark brown spot ventrally. Body with faint brown mottling on back forming indistinct saddles; midsides with series of vertically elongate spots, usually occurring in groups of 2 spots; first group below front of first dorsal fin, second below posterior end of first dorsal fin, third below beginning of second dorsal fin, fourth below second dorsal fin origin, fifth below middle of second dorsal fin, sixth below posterior end of second dorsal fin, seventh on middle of caudal peduncle, eighth at posterior end of caudal peduncle, extending onto base of caudal fin, a triangular (apex forward) brown spot on base of caudal fin, just touching last caudal peduncle spot; individual spots in each group coalesced into single large spot in largest specimen (110 mm SL). All fins grey. First dorsal fin with mottling; a black spot on membrane surrounding middle of sixth dorsal spine. Second dorsal fin with small dark brown spots forming rows. Caudal fin grey with brown spots forming 3–5 short oblique rows, fin darkest ventrally.

Coloration when freshly collected ( Fig. 4 ): Head and body yellowish tan; dark brown to blackish markings on head and pectoral-fin base similar to those described for preseserved specimens; fins translucent to slightly yellowish; first dorsal fin with mottling and reddish-yellow margin; a black spot on membrane surrounding middle of sixth dorsal spine. Second dorsal fin with brownish outer margin and small dark brown spots forming rows; caudal fin dusky yellowish brown to dark grey along posterior and ventral margins and with dark-brown spots forming 3–5 short oblique rows in central portion of fin.

Variation: Specimens collected from Lake Tebera differ slightly from specimens in the creek in being darker, with the spotting pattern obscured and chin dark to attachment of branchiostegal membranes.

Distribution Glossogobius macrocephalus is known only from the Lake Tebera basin, including the main lake and in-flowing tributaries, located in the Southern Highlands of Papua New Guinea. The type locality consisted of a small stream flowing into Lake Tabera about 4 km east of the lake. The water was exceptionally clear with respective temperature and pH values of 21°C and 7.8 recorded at the time of collection. The main lake and stream lie at an elevation of approximately 795 m. Lake Tebera is situated in a narrow, elongate basin, about 10 km long and 1.5 km wide. The basin is surrounded by steep mountains that rise to about 1000 m elevation. Apparently the drainage is isolated from the Erave-Purari system, lying just a few km to the east, although it is probably connected via subterranean flow. The lake contains numerous floating rafts of aquatic vegetation and the shoreline is swampy and lined with tall grass. Grassland and swamp habitat transition to dense rainforest on the eastern end of the basin, and the type locality is situated in the latter environment. The stream was about 3–5 m in width with a maximum depth of one m. The new species was relatively common on the mainly gravel/rock bottom. The melanotaeniid Melanotaenia herbertaxelrodi Allen, 1981 was the only other fish that was observed. Underwater observations revealed the new species was also common in the main lake during a visit to the Tebera Basin by the second author in October 1991.

Similarity to other species. Glossogobius macrocephalus differs from the lowland species of Glossogobius ( celebius , clitellus , illimis and munroi ) treated by Hoese & Allen (2012) in lacking opercular scales. It differs from Glossogobius bicirrhosus in lacking barbels extending from the mental fraenum. It differs from the highland species Glossogobius bulmeri and G. torrentis in having an elongate pelvic disc and predorsal scales reaching to near eye (versus rounded pelvic fin and predorsal scales reduced, not reaching before posterior preopercular margin). It differs from Glossogobius coatesi from the Sepik River system in having more dorsal rays (I, 9–10 versus I,8). It differs from Glossogobius hoesei from the Vogelkop Peninsula in western New Guinea in having fewer anal rays (I,8 versus I,9–10). Glossogobius macrocephalus is most similar to Glossogobius bulmeri from the highland rivers of Papua New Guinea in fin ray counts, sensory papillae and other morphological features. It differs from that species in having a slightly larger head (length 32.9–34.9% SL versus 28.5–32.4 %SL, head depth 17.3– 18.3% SL, versus 25.2–27.4 %SL), longer snout (9.4–11.7% SL versus 8.4–10.4% SL), longer pelvic fin (reaching anus versus ending short of anus).

Etymology. From the Greek makros = large and kephale = head, treated as a noun in apposition, relating to the large head of the species.

Figures

FIGURE 2. Sensory papillae of three species of Glossogobius: a. Glossogobius macrocephalus, based on holotype WAMP. 26972 – 003 and paratype WAMP. 26972 – 003; b. Glossogobius multipapillus, composite based on holotype and several Paratypes; c. Glossogobius sentaniensis, based largely on holotype, WAMP. 27852 – 004.

FIGURE 4. Photo of freshly collected specimen of Glossogobius macrocephalus from Lake Tebera, photo G. Allen.