Philypnodon macrostomus, Hoese & Reader, 2006

Hoese, Douglass F. & Reader, Sally, 2006, Description of a new species of dwarf Philypnodon (Teleostei: Gobioidei: Eleotridae) from south-eastern Australia, Memoirs of Museum Victoria 63 (1), pp. 15-19 : 16-19

Philypnodon macrostomus sp. nov.

Figures 1-3

Philypnodon sp : Hoese, Larson and Llewellyn, 1980: 171, fig. 31.3 Philypnodon sp. 1 : Merrick and Schmida, 1984: 306, fig. 256 Philypnodon sp : Hoese and Larson, 1994: 810, fig. 715 Philypnodon species: Allen, Midgley and Allen, 2002: 317

Material examined. Holotype AMS I.20111-002, 36.5 mm SL male, creek 8 km from Glenreagh , N of Coffs Harbour, NSW, 5 May 1977, D. Hoese and J. Bell . Paratypes: AMS I.20111-016, 31(25–41), taken with holotype; AMS I.20111-003, 3(28–36), cleared and stained and- 004, 4(39–40), cleared and stained, taken with holotype; AMS I.29683-008, 1(33), Karinga Creek W of Coffs Harbour, NSW, 19 Aug 1977, D. Hoese and R. McDowall; AMS I.33875-001, 1(38), Dingo Creek, 27 km W of Coffs Harbour, 5 May 1977, D. Hoese and J. Bell; NMV A.29399-001, 4(21–36), taken with holotype; NTM S.16213-001, 3(31–39), taken with holotype; QM I.37768, 3(30–31), taken with holotype .

Diagnosis. Gill opening wide, extending anteroventral to preoperculum, but not reaching to below eye, usually ending below posterior preopercular margin, sometimes as far forward as midway between posterior preopercular margin and eye. Head papillae in transverse pattern (figs 2–3). Body generally dark brown, with darker brown mottling on sides; 1st dorsal with black stripes in adult males. Jaws reaching to behind eye in mature males, variably developed in juvenile males and females, usually reaching below middle of eye to near end of eye. Tongue tip rounded to truncate.

Description. An asterisk indicates count of holotype. 1st dorsal fin VI (in 8*), VII (23), VIII (4); 2nd dorsal-fin rays I,8 (8), I,9 (21*), I,10 (5); anal-fin rays I,8 (10), I,9 (22*), I,10 (3); pectoral rays 15 (4), 16 (21*), 17 (9). 18 (1) segmented caudal rays 8/7 (12), 8/8 (1*); branched caudal rays 7/6 (12*), 7/7 (1); procurrent caudal rays 9/8 (1), 9/9 (1), 10/8 (1), 10/10 (1), 11/10 (3); predorsal scale count 4(1), 5(1), 7(1), 8 (3), 9 (2), 10 (1), 11 (6), 12 (2), 13 (6), 14 (6*), 15 (1); longitudinal scale count 34 (5), 35 (6*), 36 (6), 37 (10), 38 (5), 39 (1), 42 (1); transverse scale count ( TRDB) 9 (16*), 10 (12), 11 (7); gill rakers on outer face of 1st arch 2+1+8 (7), 3+1+8 (1), 2+1+9 (22), 2+1+10 (2); lower rakers on outer face of 2nd arch 7 (9), 8 (22), 9 (3); vertebrae 12+19 (3), 13+18 (2), 13+19 (2).

Head distinctly depressed, flat on top, length 29.5% SL in holotype (range 29.5–33.6% SL); eyes dorso-lateral, 6.8% SL (6.4–7.4% SL), interorbital wide, slightly less than eye diameter in juveniles to about 1.5 times eye diameter in adult; snout short, about equal to eye diameter, 8.1% SL (7.8–9.2% SL); cheeks distinctly bulbous in adult males; mouth slightly oblique forming an angle of about 35–45° with body axis; posterior margin of jaws below mid-eye in females, to below or just beyond posterior end of eye in males, length of upper jaw 15.4% SL (13.7–18.7% SL) in males and 10.2–14.8% SL in females; teeth in both jaws small and curved, anteriorly in 2 or rarely 3 rows, tapering laterally to a single row; posterior nostril with raised rim, approximately 1 nostril diameter in front of eye in a horizontal line between mid-eye to upper pupil margin; anterior nostril at end of short tube, just behind middle of upper lip, in a horizontal line between mid-eye to lower margin of pupil; gill rakers slender, much shorter than filament length on outer face of 1st arch, longest rakers near angle of arch about one-quarter length filament length; rakers on inner face of 1st arch and following arches short and denticulate.

Body slender, slightly compressed anteriorly, becoming very slender posteriorly; depth at pelvic-fin origin 14.6% SL (14.5–18.8% SL); depth at anal-fin origin 14.1% SL (13.1–17.7); caudal peduncle slender and elongate, length 29.8% SL (24.1– 30% SL), least depth 9.2% SL (8.2–10.5% SL).

Head naked; predorsal partly scaled, midline scaled to above posterior preopercular margin to midway between posterior preopercular margin and eye (just before posterior preopercular margin in holotype), often naked in specimens less than 15 mm SL; scales on side of nape variable, sometimes with scales as far forward as midline scales (in holotype), but often reduced, sometimes naked forward of pectoral-fin base. Body scales ctenoid; body fully covered with scales, becoming cycloid above a line from upper gill attachment to below posterior quarter of 1st dorsal fin; belly covered with small cycloid scales, midline naked in specimens with reduced predorsal scales, pectoral-fin base normally covered with small scales, naked in specimens with reduced predorsal scales, prepelvic area covered with small cycloid scales, except for a triangular area behind gill opening to fully naked in specimens with reduced predorsal scales.

1st dorsal fin low, with rounded margin, fin reaching to or just short of 2nd dorsal fin when depressed; 1st dorsal spine slightly shorter than 2nd spine, 2nd to 4th spines subequal in length, 5th spine subequal in length to 1st spine; 6th spine slightly shorter than 5th spine, 7th spine shorter than 6th spine; 2nd dorsal fin separated from 1st dorsal fin, fin elevated, slightly higher than 1st dorsal fin, subequal to body depth, 1st segmented ray usually branched, other rays always branched; anal fin origin below and slightly behind 2nd dorsal-fin origin, usually below 2nd segmented dorsal ray, fin subequal in height to 2nd dorsal fin, 1st segmented rays usually branched, other rays branched; pelvic fins completely separate, pelvic fin short, reaching approximately half distance from pelvic-fin origin to anal-fin origin, length 18.4% SL (14.1–18.4% SL), pelvic-fin rays I,5, all segmented rays branched, rarely innermost ray unbranched; pectoral fin with broadly rounded margin, reaching to above or slightly before anus, length 22.8% SL (19.6–24.2% SL), pectoral rays branched, upper and lowermost sometimes unbranched; caudal fin with rounded posterior margin, caudal length 17.9% SL (17.0–25.1% SL).

Urogenital papilla of male flattened dorso-ventrally, with small lobes laterally; papilla of female broad and rounded, with an indentation posteroventrally.

Sensory papillae. Transverse papillate pattern; all papilla lines with papillae at right angle to axis of line. Sides of head with 6 lines radiating from eye; preopercular mandibular series with 10–14 transverse lines from chin to middle of preoperculum. Other papillae as shown in figs 2 and 3.

Coloration of freshly collected specimens. (holotype and male paratype). Head and body dark brown, lighter brown to pale orange ventrally. Lips dark brown with diffuse orange pigment on posterior half; 2 dark-brown stripes extending posteroventrally from posteroventral margin of eye onto cheeks, not reaching posterior preopercular margin; a large light-brown oval area behind tips of dark stripes; an irregularly shaped light-brown stripe extending from below eye posteroventrally to just above posterior end of jaws; operculum with light-brown almost horizontal stripe in line with interspace between dark stripes extending from eye; a similar light-brown stripe dorsally on operculum; rest of operculum dark brown; body scales edged in dusky-brown pigment, dorsally broadly edged with dark-brown pigment, scale centres often with light thin vertical line; series of 2–3 small black spots above pectoral-fin base; pectoral-fin base black dorsally followed by white irregular bar extending full length of pectoral-fin base; caudal peduncle with dark-brown vertical bar, with a short anterior extension. Dorsal fin with 2 black curved stripes following contour of fin; distal margin of dorsal fin with broad orange band, followed by black stripe curving to meet body, followed ventrally by a lighter orange to brown stripe, followed ventrally by 2nd black stripe; anteriorly white blotches below stripe; 2nd dorsal fin with black distal margin (about one-quarter of fin), followed ventrally by 4 curved, oblique stripes, with orange to white interspaces. Anal fin with scattered melanophores giving fin a gray appearance; base of fin lighter, followed distally by pale black stripe followed by lighter stripe, followed by dark gray stripe, distal tip lighter than rest of fin. Pectoral and pelvic fins white to dusky. Caudal fin pale orange basally, becoming dark gray posteriorly; series of 2–4 curved dark bands, extending across all, but uppermost 1 or 2 and lowermost 1 or 2 segmented caudal rays, each band formed from 2–3 rows of small black spots on fin rays, generally no spots on membranes between rays.

Coloration in alcohol. Head and body light brown, paler ventrally, males generally darker than females. 2 faint brown stripes extending posteroventrally from posteroventral margin of eye onto cheeks, not reaching posterior preopercular margin; distinct light-brown areas and stripes on head present in fresh material not visible; operculum light brown; body scales edged in light-brown pigment, dorsally broadly edged with dark-brown pigment; large black spot above pectoral-fin base with pale areas; black spot dorsally on pectoral-fin base, a thin brown band extending from spot ventrally covering pectoral-fin base, no pale band visible; large dark-brown area at posterior end of caudal peduncle forming a vertical band, a vertical band with a horizontal extension, or triangular mark. Dorsal fin with 2 black curved stripes following contour of fin as in fresh material, orange and white areas in fresh material becoming light brown; 2nd dorsal fin with black to gray distal margin (about one-quarter of fin), followed ventrally by 4 curved, oblique dark stripes, with light-brown interspaces. Anal fin with scattered melanophores giving fin a uniform gray appearance. Pectoral and pelvic fins clear, without pigment. Caudal fin pale light-brown to gray, with series of 2–4 curved dark bands, extending across all but uppermost 1 or 2 and lowermost 1 or 2 segmented caudal rays, each band formed by 2–3 rows of small dark brown spots on fin ray, generally no spots on membranes between rays.

Distribution. Philypnodon macrostomus is widely distributed in coastal rivers from Brisbane, Qld, throughout NSW, Vic. and eastern SA in freshwater and in brackish to full strength seawater in upper reaches of estuaries. It is also found in the Lower Murray R. system from scattered localities. The related Philypnodon grandiceps occurs north to the Burdekin R., Qld. Specimens of the dwarf species from the Mary R. north of Brisbane are currently under study, but do not appear to be conspecific and will be reported on later in a revision of the genus. Similarly, specimens from the Cudgegong R. in Macquarie R. drainage in central NSW lack predorsal scales and possibly represent a separate species to be treated in the revision.

Etymology. from the Latin macro = large and stomus = mouth, alluding to the large mouth that develops in males.

Remarks. Philypnodon macrostomus differs from Philypnodon grandiceps in having a narrower gill opening (below posterior preopercular margin versus below eye in P. grandiceps ); sides of belly without vertical bands (versus 4–5 thin brown almost vertical lines); tongue tip rounded to truncate (versus bilobed); body often mottled (versus body uniformly coloured) and having more numerous vertebrae (usually 31–32, versus usually 29–30). The species also reaches a much smaller size, usually less than 50 mm SL, with the largest specimen known 60 mm SL(versus commonly reaching a size of 70mm SL and reaching a maximum size of almost 90 mm SL).

While the species is widely distributed, it shows considerable variation over the range of the species. The intensity of coloration varies from light brown to almost black. Fin ray counts vary considerably, but without any clear geographical pattern. More detailed analysis of geographical variation will be presented in a revision by the authors at a later time.

The differences in the urogenital papilla were minor in comparison with other gobioid fishes and it was difficult to sex the species. Poor preservation can result in distortion of the papilla.

Figures

Figure 1. Holotype of Philypnodon macrostomus, AMS I.20111-002, 36.5 mm SL male.

Figure 2. Lateral view of head showing sensory papillae, largely based on holotype, drawing by S. Reader.

Figure 3. Dorsal view of head showing sensory papillae, largely based on holotype, drawing by S. Reader.