Glossogobius nanus, Hoese & Allen & Hadiaty, 2017

Hoese, Douglass F., Allen, Gerald R. & Hadiaty, Renny K., 2017, Description of three new species of dwarf Glossogobius from New Guinea and northern Australia, Cybium 41 (2), pp. 179-193 : 185-187

Glossogobius nanus , new species

( Figs 7 , 8 , 1B , 4B, 4C , 12; Tabs I-V)

Glossogobius sp. – Allen & Hoese, 1980: 58 (Jardine and

Archer rivers, Cape York, Queensland).

Glossogobius sp. 2 . – Allen, 1991: 183, pl. 15, fig. 1 (in part, Papua New Guinea).

Glossogobius sp. 3 . – Allen et al., 2002: 271 (Cape York,

Queensland).

Material examined

Holotype. – QM I.40670, 37.5 mm SL male, Myall Creek , Weipa, Queensland, M. Hammer.

Paratypes. – Cape York, Queensland, Australia: AMS I.21240-001, 13(10-26), Packsaddle Creek , 11°08’S, 142°23’E, Aug. 1979, D. Hoese and G. Allen; AMS I.21241-001, 17(11-22), Packsaddle Creek , 11°08’S, 142°23’E, Aug. 1979, D. Hoese and G. Allen; AMS I.21238-001, 15(11-20), Jardine River , 11°08’S, 142°25’E, Aug. 1979, D. Hoese and G. Allen; QM I.17949, 5(18- 32) Jardine River , 13-15 Aug. 1980, R. Leggett; QM I.21787, 6(15- 25), Jardine River , 27 Aug.-5 Sep. 1985, R. Leggett; QM I.26727, 1(29), 30 km south of Bamaga , 11°09’S, 142°21’E, 1 Aug. 1988, S.H. Midgley; WAM P.26718-004, 2(18-25), Packsaddle Creek , Jardine River system, 11°08’S 142°23’E, 30 Aug. 1979, G. Allen and D. Hoese; AMS I.21237-002, 6(14-26), Creek just south of Jardine , Cape York, 11°09’S, 142°22’E, 28 Aug. 1979, D. Hoese and G. Allen; AMS I.21237-029, 6(14-22), creek just south of Jardine River , 11°09’S, 142°22’E, 28 Aug. 1979, D. Hoese and G. Allen; WAM P.26381-018, 2(17-20), creek 1 km south of Jardine River , 11°10’S, 142°22’E, 21 Sep. 1978, G. Allen and R. Steene; AMS I.21248-009, 6(22-29), McDonnell Creek , Jackson River System, 11°37’S, 142°28’E, 1 Sep. 1979, D. Hoese; AMS I.21249-003, 1(27), Cockatoo Creek , Jackson River System, 11°38’S, 142°28’E, 2 Sep. 1979, D. Hoese and G. Allen; QM I.28190, 10(27-29), Cockatoo Creek , 11°32’S, 142°47’E, Aug. 1988, S.H. Midgley; QM I.39558, 3(18-22.5), Bromley Road Crossing, Olive River , 12°14.01’S, 142°52.65’E, 12 Oct. 1992; AMS I.21250-004, 2(19- 29), Palm Creek , Wenlock River system, 12°04’S, 142°33’E, 2 Sep. 1979, D. Hoese and G. Allen; QM I.39550, 3(16-21), Snake Creek , Olive River system, 12°17.63’S, 142°51.48’E 21, Nov. 1992; AMS I.23275-004, 76(14-22), Schramm Creek , Wenlock River system, 12°23’S, 142°36’E, 8 Oct. 1982, D. Hoese and D. Rennis; AMS I.23283-005, 15(11-31), Bellvue Creek , Embley River system, 12°42’S, 141°59’E, 12 Oct. 1982, D. Hoese and D. Rennis; AMS I.23263-006, 21(15-25), east of Weipa, 12°47’S, 142°19’E, 4 Oct. 1982, D. Hoese and D. Rennis; AMS I.47250-001, 2(41-43), captive bred from Jardine River, R. Leggett .

Non-type material. – Cape York, Queensland, Australia: QM I.26719, 10(27-30), Cockatoo Creek , 11°32’S, 142°27’E, Aug. 1988, S.H. Midgley ; QM I.28173, 2(19-20), Olive River , Bromley Crossing , Bromley Station , 12°14’S, 142°52’E, 12 Oct. 1992, B. Herbert; AMS I.21233-001, 43(13-21), Creek 60 km N of Coen, 13°26’S, 142°56’E, 27 Aug. 1979, D. Hoese; AMS I.21249- 001, 9(11-21), Cockatoo Creek , Jackson River System, 11°38’S, 142°28’E, 2 Sep. 1979, D. Hoese and G. Allen; AMS I.23275-[ EX 004 ], 7(14-22), cleared and stained, Schramm Creek , Wenlock River system, 12°23’S, 142°36’E, D. Hoese and D. Rennis; AMS I.23273-002, 1(18), Ducie, River, 12°07’S, 142°16’E, 8 Oct. 1982, D. Hoese and D. Rennis; AMS I.23274-004, 20(14-20), Ducie River , 12°15’S, 142°30’E, 8 Oct. 1982, D. Hoese and D. Rennis; AMS I.23276-002, 6(13-20), Arthur Creek, Wenlock River system, 12°44’S, 142°30’E, 8 Oct. 1982, D. Hoese and D. Rennis .

Northern Territory, Australia: NTM S.15888-019, 1 (half taken for DNA), Cato River , 12°22’31”S, 136°22’46”E, 7 Jul. 2004, H. Larson .

Papua New Guinea: WAM P.27796-003, 2(25-26), Small creek 32 km N of Kiunga on Tabubil Road, Fly River system, 5°55’S, 141°17’E, 6 Sep. 1982, G. Allen and J. Paska ; WAM P.27808, 1(29), tributary of Fly River at Kiunga, 21 Sep. 1982, G. Allen and J. Paska .

Diagnosis

Mouth small, reaching to below a point between anterior margin of pupil and anterior margin of eye; mental fraenum indistinct in most specimens, developed as a low rounded to truncate fold in well preserved specimens; predorsal area largely naked to about half scaled, sides scaled forward to above posterior opercular margin, midline naked to about half scaled; cheek and operculum naked; pectoral-fin base and prepelvic area naked; first dorsal fin with black spot posteriorly surrounding area near base of sixth dorsal spine; second dorsal rays usually I,8; anal rays usually I,6; pectoral rays 14-16; longitudinal scale count 24-26; predorsal scale count 0-2 in Australian specimens, 5-7 in Fly River specimens; transverse scale count (TRB) 7.5; vertebrae usually 11+15 = 26; pelvic disc thin and elongate, width much less than length; preoperculum with 2-3 pores in adult, often absent in juveniles below 19 mm SL, lateral canal tube above operculum usually absent in Australian specimens, but present in specimens above 40 mm SL from Australia; lateral canal pore between infraorbital pore and terminal lateral canal pore present or absent.

Description

Counts based mainly on 55 specimens, measurements taken on 30 specimens above 24 mm SL, with 345 specimens examined. First dorsal spines 6(55*); second dorsal rays I,7-9, usually I,8; anal rays I,5-7, usually I,6; pectoral rays 14-15; predorsal scale count 0-2; longitudinal scale count 24(16), 25(14*), 26(6); transverse scale count (TRB) 6.5(3), 7.5(25*), 8.5(2); gill rakers on outer face of first arch 2+0-1+5-7 = 8-9; lower gill rakers on outer face of second arch 0+6-7; segmented caudal rays 9/8(30*); branched caudal rays 6/6(2), 6/7(1), 7/6 (13*), 7/7(6), 8/7(10). Other meristics shown in tables I-V.

Head slightly depressed, length 26.5-31.8% SL; cheeks slightly bulbous, head width at posterior preopercular margin 17.5-21.5% SL; depth at posterior preopercular margin 15.9-18.5% SL. Snout rounded in dorsal view; concave in side view in juveniles, convex in adults, with distinct notch formed from ascending process of premaxilla just before eye; 7.2-9.3% SL. Eye slightly longer than snout in juveniles and subequal to snout in adults above 20 mm SL, 6.5-9.1% SL. Small bump between nostrils below anterior nostril present, but very low. Anterior nostril at end of short tube, about one nostril diameter above upper lip. Posterior nostril pore without elevated rim, about one nostril diameter, from eye and 1-1.5 diameters from anterior nostril. Preoperculum short, distance from end of eye to upper posterior preopercular margin slightly less than snout length. Postorbital moderate, subequal to distance from tip of snout to a point above end of pupil to just behind end of eye. Gill opening reaching to below a point just behind posterior preopercular margin. Jaws forming an angle of 30-45° with body axis; upper margin of upper jaw in line with middle to lower margin of pupil, upper jaw length 11-12.5% SL in adult males and 9.1-11% SL in adult females. Teeth in upper jaw: outer row of teeth conical, slightly enlarged, teeth extending full length of premaxilla; an inner row of slightly smaller conical teeth. Teeth in lower jaw: teeth in outer row conical, slightly enlarged and close-set confined to anterior half of dentary; a second inner row of slightly smaller teeth extending full length of dentary; an innermost row of posteriorly directed depressible teeth anteriorly on inner face of dentary. Tongue tip distinctly bilobed. Gill rakers on outer face of first arch triangular, very short, much less than filament length. Rakers on inner face of first arch and other arches shorter than rakers on outer face of first arch and denticulate. Body covered mostly with large ctenoid scales, anteriormost one or two rows cycloid; midline of belly naked or with a few cycloid scales before anus and a large naked patch behind pelvic fin insertion and a few rows of cycloid scales extending forward to below pectoral fin insertion ventrally. First dorsal fin low and rounded in both sexes, lower than body depth at anal fin origin, fourth to sixth spines reaching to about the same point just before to just beyond origin of second dorsal fin when depressed; dorsal origin above a point just behind pelvic fin insertion. Second dorsal fin of slightly higher than first dorsal fin, but lower than body depth at anal fin origin. Anal fin slightly lower than second dorsal fin, posterior most rays elongate in mature males, reaching about half way to caudal fin when depressed, reaching less than half way to caudal fin in mature females. Pectoral fin with rounded to pointed margin, reaching to above or just behind anal fin origin, 29.3-31.7% SL in mature males and 23.6-29.6% SL in mature females. Pelvic fin thin and oval, reaching to or just beyond anus, but usually not to anal fin origin, fifth ray with few branches and about 8-12 terminal tips, second ray with most sequential branching beginning before middle of ray.

Figures

Figure 1. – Sensory papillae in three dwarf species of Glossogobius, composite drawing, based largely on holotypes. A: G. gnomus; B: G. nanus; C: G. pumilus. Numbers indicate papilla lines after Akhito and Meguro (1975) and in descriptions here. Scale bar = 5 mm.

Figure 4. – Dark area indicating anterior extent of predorsal and prepelvic scales and head pores in various populations and species of dwarf Glossogobius. A: Glossogobius gnomus; B: G. nanus, Australia; C: G. nanus, Fly River; D: G. pumilus, Bensbach River; E: G. pumilus, Timika region. Scale bar = 5 mm.

Figure 7. – Freshly collected holotype of Glossogobius nanus, QM I.40670, 37.5 mm SL. Photo M. Hammer.

Figure 8. – Live individual from type locality of Glossogobius nanus. Photo M. Hammer.