Glossogobius pumilus, 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 : 189-192

Glossogobius pumilus , new species

( Figs 1C , 4D, E , 9 , 10 , 11 , 12; Tabs I-V)

Glossogobius sp. 2 . – Allen et al., 2000 (in part, Timika

Region, New Guinea).

Material examined

Holotype. – WAM P.27823-011, 32 mm SL male, 17 km upstream of Bensbach lodge, 8°53’S, 141°12’E, 1 Oct. 1982, G. Allen and J. Paska.

Paratypes. – Papua New Guinea: AMS I.27507-001, 31 (21-32) and WAM P.27823-001, 109(13-35), taken with holotype ; WAM P.27817-006, 2(31-32), 5 km upstream of Bensbach lodge, 8°51’S, 141°13’E, 29 Sep. 1982, G. Allen and J. Paska; Papua , Indonesia: WAM P.31296-003, 11(25- 40) and MZB 23337 , 2 (29-32), south of Timika, E side of Portsite road, approximate km 24, 22 Apr. 1997, 04°37.47’S, 136°57’E, G. Allen and Party ; WAM P.31756-002, 22(15-29) and AMS I.47250-001, 6(21-27), south of Timika , 04°41’S, 136°54.31’E, 7 Aug. 2000, G. Allen and K. Hortle .

Diagnosis

Mouth small, reaching to below a point between anterior margin of pupil and anterior margin of eye; mental fraenum a small rounded protrusion or triangular, without distinct lateral lobes; predorsal partly scaled, midline scaled forward in adult to above a point between middle of operculum and just behind posterior preopercular margin; cheek and operculum naked; pectoral-fin base and prepelvic area naked; pelvic disc thin and oval, longer than wide and reaching to anus in adults; first dorsal fin with black spot posteriorly surrounding area near base of sixth dorsal spine; second dorsal rays usually I,9; anal rays usually I,7; pectoral rays 13-16; longitudinal scale count 24-27; predorsal scale count 0-9; transverse scale count (TRB) usually 7.5; vertebrae usually 11+16 = 27, preoperculum without pores, no lateral canal tube above operculum; lateral canal pore between infraorbital pore present in adults and terminal lateral canal pore present.

Description

Counts based on 59 specimens, measurements taken on 24 specimens 24-41 mm SL. First dorsal spines 6(40*); second dorsal rays I,8-10, usually I,9; anal rays I,6-7, usually I,7; pectoral rays 13-16, usually 14; longitudinal scale count 24(5), 25(11), 26(14). 27(5*), 28(1); predorsal scale count 0-9; transverse scale count (TRB) 7/5(28), 8.5(9*); gill rakers on outer face of first arch 1+0+5(1), 1+1+5(2), 1+1+6(3), 2+1+7(1) = 6-9; gill rakers on outer face of second arch 0+6(6), 0+7(1) = 6-7; segmented caudal rays 8/7(1), 9/8(29*); branched caudal rays 7/6(5), 7/7(8*), 8/7(19). Other meristics shown in tables I-V.

Head slightly depressed, length 29.2-33.5% SL; cheeks bulbous in adults over 22 mm SL, slightly bulbous in juveniles, head width at posterior preopercular margin 16.4- 20.3% SL; depth at posterior preopercular margin 14.3-17.9% SL. Snout rounded in dorsal view; convex or concave in side view, with distinct notch formed from ascending process of premaxilla just before eye in some specimens; 7.1-11.5% SL. Eye slightly longer than snout in juveniles and subequal to snout in adults above 20 mm SL, 6.3-8.5% SL in adults. Small bump between nostrils below anterior nostril present, but very low. Anterior nostril at end of short tube, slightly less than one nostril diameter above upper lip. Posterior nostril a pore without elevated rim, about 1.5-3 nostril diameters, from eye and 1.5-2 nostril 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 37-47° with body axis; upper margin of upper jaw in line with or just below lower margin of eye, posterior end below anterior margin of eye in females and immature males and below anterior half of pupil in mature males, upper jaw length 12.2-15.6% SL in adult males and 10.4-12.2% 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 smaller conical teeth; an innermost row of enlarged depressible conical teeth anteriorly on premaxilla. 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 the full length of the dentary becoming larger posteriorly; an innermost row of posteriorly directed, curved 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, cycloid before a line from pectoral fin insertion to below first dorsal fin; belly usually with a few cycloid scales before anus and a large naked patch behind lum (smallest specimen examined 19 mm SL); no short tube pelvic fin insertion and a few rows of cycloid scales extend- above operculum; no preopercular pores ( Figs 2 , 4D, 4E ). ing forward to below pectoral fin insertion ventrally. First dorsal fin low and rounded in both sexes, lower than body Papillae depth at anal fin origin, fourth to sixth spines reach to about Line 1(before nasal pore) present and very short, not the same point just before to just before origin of second dor- reaching snout tip. Line 2 extending from behind nasal pore sal fin when depressed; first dorsal fin origin above a point arching upwards and backwards to opposite side of head. just behind pelvic fin insertion. Second dorsal fin slightly Line 5 (suborbital) short, extending from below front half of higher than first dorsal fin, but lower than body depth at anal eye to infraorbital pore. Line 6 (suborbital branch) absent. fin origin; posterior rays reach just over half way to upper Line 7 (LL cheek row) extending from below front of eye caudal fin base in mature females and to base of upper cau- and usually continuous with papillae behind jaws, extenddal fin in mature males. Anal fin slightly lower than second ing posteriorly to just beyond eye. Line 8 (LT cheek row = dorsal fin, posterior most rays very elongate in mature males, row b) extending from jaws to end of preoperculum. Line 9 reaching to lower rays of caudal fin when depressed, reach- (LL cheek row) short extending from below front half miding over half way to caudal fin in mature females. Pectoral dle of eye arching upward then downward to just behind eye. fin with rounded margin, reaching to above a point between Line 10 (LL cheek row) extending from jaws to just beyond anus and behind anal fin origin, 23.3-31.2% SL. Pelvic fin end of eye and not reaching preopercular margin. Line 11 thin and elongate, reaching to or just beyond anus in males (LT row d) extending to below posterior end of eye. Line 12 (21.2-28.5% SL) and to or just anterior to anus in females (Outer POP-mandibular) continuous from chin to near lower (19.7-23.9% SL), fifth ray with few long branches and about preopercular pore, usually with a gap of no papillae behind 8-12 terminal tips. posterior tip of jaws. Line 13 (Inner POP-mandibular) continuous from chin to lower preopercular pore. Line 20 (Oper- Head pores cular VT) composed of single row of papillae extending Posterior nasal pore just medial and slightly above poste- from just behind upper preopercular pore to lower margin of rior nostril; anterior interorbital pore above a point between operculum. Line 21 (Upper OT) separate from Line 20 slopanterior margin of pupil to half way to anterior margin of ing downward posteriorly, ending close to posterior opercueye; posterior interorbital pore above posterior margin of lar margin. Line 22 (Lower OT) almost horizontal and compupil; postorbital pore behind upper margin of eye; infraor- posted of 6-10 papillae reaching to near end of operculum. bital pore below postorbital and behind middle of eye; lat- Other papillae shown in figure 1C. eral canal pore above preoperculum present just before posterior preopercular margin; terminal lateral canal pore above Coloration a point just behind posterior preopercular margin of opercu- Head and body brown. Head with scattered dark brown or black small spots and with larger mottling in adults; a broad dark stripe from anteroventral margin of eye to behind middle of upper lip, extending onto lips followed posteriorly by a broad white stripe extending from eye to over posterior third of lips, followed by a thin dark brown to black stripe from posterior margin of eye to behind posterior tips of jaws, becoming broader ventrally and often broken into two or three round spots; a small dark brown to black spot, smaller than pupil diameter almost in contact with posteroventral margin of eye; rest of cheek with large scattered dark brown to black mottling; chin and isthmus dark brown in mature males, chin dark brown with rest of ventral surface of head lighter in mature females; mental fraenum dark brown,

sometimes only at sides of fraenum; lips dark brown except white at posterior tip, bar from Figure 12. – Map showing known locations of dwarf species of Glossogobius anteroventral margin of eye bars crossing lips, but from Australia and New Guinea, each symbol may represent multiple samples for G. nanus and G. pumilus ; solid circle: G. nanus ; square: G. gnomus ; star: G. lips often dark and band not distinct on lips. Body pumilus . brown, with an irregular shaped dark brown stripe dorsally on midside breaking up into irregularly shaped dark brown spots on caudal peduncle ( Fig. 11 ). A series of 8 elongate spots on midside of body, with X-shaped extensions dorsally and ventrally, each covering 1-2 scales in a longitudinal direction along midside; first spot below anterior quarter of first dorsal fin; second below posterior quarter of first dorsal fin, sometimes connected to first spot, third spot below a point between first and second dorsal fin; fourth and fifth spots below second dorsal fin; sixth and seventh spot on caudal peduncle; eighth spot triangular at posterior end of caudal peduncle, without dorsal or ventral extensions and apex pointing anteriorly. First dorsal fin with a thin black stripe near base, connecting to an ocellated black spot surrounding middle of sixth dorsal spine, spot fainter in females and immature males. Second dorsal fin with black spots forming 2 rows ventrally, distal margin of fin dark brown. Pectoral fin base with a round to oval spot, smaller than pupil diameter dorsally and in some specimens a second smaller spot near ventral base, fin translucent without spots. Caudal fin with upper rays covered with brown spots forming wavy bands (usually 4–6) on dorsal two-thirds of fin, ventral third gray to dark brown; a large black median spot on dorsal midline of caudal peduncle followed by a white spot at base of caudal fin, followed by a small dark spot on caudal fin. Anal fin whitish to translucent in young and gray in adults of both sexes. Pelvic fins translucent in young, gray to dark brown in adults of both sexes.

In freshly collected individuals from Bensbach River ( Fig. 10 ), the overall coloration is similar to that described for preserved material, except as follows: distal tips of two dorsal and caudal fins orange and anal fin and ventral quarter of caudal fin gray with an orange tinge and the pectoral fins white. A live individual from the Timika region is similar in coloration, except that the pectoral fin is translucent ( Fig. 11 ).

Distribution

The species is known only from three localities, the Bensbach River in Papua New Guinea and the Timika Region in Papua, Indonesia. The species appears common in lowland clear to turbid streams (less than 50 m elevation) and also occurs in peat swamp habitat in the Timika region . It belongs to a relatively diverse fish species assemblage at the type locality, consisting of 16 species that also includes clupeids, plotosids (2 species), atherinids, melanotaeniids (2 species), ambassids, apogonids (2 species), terapontids, toxotids, eleotrids (3 species), and soleiids .

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 2. – Generalised drawing of head showing terminology used for sensory pore in dwarf species of Glossogobius. See Methods for explanation of abbreviations. 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 9. – Preserved holotype of Glos- sogobius pumilus, WAM P.27823-011, 32 mm SL male.

Figure 10. – Freshly collected para- type of Glossogobius pumilus, WAM P.27823-011, 33 mm SL male from Bensbach River. Photo G.Allen

Figure 11. – Live individual from Timi- ka area of Glossogobius pumilus. Photo G. Allen.