Chaunax gomoni, Ho & Satria, 2015

Ho, Hsuan-Ching, Kawai, Toshio & Satria, Fayakun, 2015, Species of the anglerfish genus Chaunax from Indonesia, with descriptions of two new species (Lophiiformes: Chaunacidae), Raffles Bulletin of Zoology 63, pp. 301-308 : 302-305

Chaunax gomoni sp. nov.

New English name: Gomon’s frogmouth

( Figs. 1A, B , 2A, B ; Tables 1 , 2)

Holotype. HUMZ 193991 (1, 174), Baruna Jaya IV, st. 21, 8°15.5’S, 110°22.0’E, 8°14.8’S, 110°20.3’E, off Java, Indonesia, eastern Indian Ocean , 290–295 m, 11 May 2005.

Paratype. BMNH 1986.9 . 29.18 (1, 134), S of Java and Bali, Indonesia, E Indian Ocean, coll. P. Whitehead. CAS 34598 (1, 121) , E of Dilao Point, Batangas Bay , the Philippines, 294–329 m, 1 August 1966, coll. J.E. Norton. HUMZ 191207 (1, 181) , HUMZ 191208 (1, 126) , HUMZ 191209 (1, 87) , MZB 22712 (formerly HUMZ 191210 , 1 , 126 ) , Baruna Jaya IV, st. 2, 8°6.17’S, 108°34.5’E, 8°4.22’S, 108°34.0’E, 180–210 m, 6 September 2004 . USNM 168256 (1, 138) , Albatross , st. 5117, 13°52’22”N, 120°46’22”E, Balayan Bay and Verde Island, 216 m, 21 January 1908 (from dark green mud) .

Non-types. HUMZ 193631 (1, 68), Baruna Jaya IV, st. 1, 8°4.7’S, 108°24.7’E, 8°4.4’S, 108°23.4’E, off Java, 246–263 m, 4 May 2005 . HUMZ 193992 (1, 30), same as holotype . HUMZ 194739 (5, 23-30), Baruna Jaya IV, st. 24, 8°27.2’S, 110°39.3’E, 8°27.0’S, 110°37.6’E, off Java, 353–359 m, 11 May 2005 .

Diagnosis. A species of the Chaunax abei -group with a unique un-pigmented peritoneum and the following combination of characters: irregular green spots on dorsal surface when freshly dead, turning into dark brown when preserved; head length 39.5–40.8% SL; 10 gill rakers on second gill arch; 12 or 13 pectoral fin rays; 29–38 neuromasts on lateral-line proper and 11–14 on pectoral series.

Description. Morphometric and meristic data are given in Table 1 ; the following data is that of the holotype, followed by variations in paratypes, if different, enclosed by parentheses.

Dorsal-fin rays III, 12; pectoral-fin rays 13 (12 or 13); analfin rays seven; caudal-fin rays nine. Head length 2.5 in SL; head width 6.3 (5.8–6.3) in SL and 2.5 (2.3–2.5) in HL; pre-dorsal length 2.0 (1.9–2.1) in SL; pre-gill-opening length 1.7 (1.6–1.9) in SL; pre-preopercular length 3.9 (3.5–3.9) in SL and 1.6 (1.4–1.6) in HL; upper jaw 5.0 (4.7–5.0) in SL and 2.0 (1.9–2.0) in HL; illicial length 8.9 (6.8–9.8) in HL; eye diameter 5.3 (5.0–6.8) in HL; post-dorsal fin length 5.5 (5.1–6.2) in SL and 2.2 (2.0–2.5) in HL; post-anus length 3.2 (3.0–3.8) in SL and 1.3 (1.2–1.5) in HL; post-anal fin length 5.9 (5.7–6.7) in SL and 2.4 (2.3–2.6) in HL; caudal peduncle depth 4.5 (4.4) in HL; caudal-fin length 3.5 (3.1–3.6) in SL and 1.4 (1.2–1.4) in HL.

Head globular, skull elevated above body posteriorly; trunk and tail robust, weakly compressed, tapering posteriorly to caudal-fin base; ventral surface of belly flattened; skin thick, loose and flaccid; caudal peduncle short. Eyes rounded, directed laterally; covered by dermal membrane, broadly connected to adjoining skin, forming clear window; interorbital space broad, convex.

Illicium relatively slender, its length less than eye diameter; esca depressed, forming a large central plate bearing many dark brown cirri; second dorsal-fin spine close to illicium, embedded under skin and not detectable externally; third dorsal-fin spine situated at about midpoint of predorsal distance, embedded beneath skin. Illicial trough oval, slightly concave, uniformly narrow, its length about twice its width. Origin of soft dorsal fin slightly behind midpoint of body; pectoral fin emerging laterally near middle of body, slightly anterior to vertical through gill opening; pelvic fin on breast, well anterior to pectoral fin; anus situated about third-fourths of way along body; anal-fin origin about fourfifths of way along body, tip nearly reaching caudal-fin base when depressed.

Both nostrils anterior to eye; anterior nostril surrounded by fleshy membrane, its posterior part taller than anterior portion; posterior nostril a circular depression; mouth wide, superior, its opening nearly vertical; lower jaw robust, protruding slightly in front of upper jaw; maxilla tapering, narrow dorsally, broadly expanded ventrally; blunt symphyseal spine on symphysis of lower jaw.

Broad transparent membrane on first gill arch; first ceratobranchial well connected to opercular wall and first epibranchial entirely free from it; gill filaments present on second to fourth gill arches, two rows of gill filaments on second and third gill arches, single row of gill filaments on fourth gill arch; filaments on inner rows of third and fourth gill arches about two-thirds length of filaments on other arches; inner surface of fourth gill arch completely connected to body. Single row of 14 (13–14) rakers on first gill arch, four on upper limb and 10 (9–11) on lower limb, 10 rakers on outer row of second arch, 11(10–11) rakers on outer row of third arch, and single row of eight (seven to eight) rakers on fourth arch.

Distance between lateral-line neuromast complex longer than width of the complex; three to four (mainly three) pairs of short spines bridging each neuromast. Lateral-line neuromast counts: supraorbital (AB) 11 on right side/12 on left side (11–12); premaxillary (AC) eight; upper preopercular (BD) two; infraorbital (CD) seven on right side/six on left side (six or seven); lower preopercular (DG) three; mandibular (EF) six; hyomandibular (FG) three; pectoral (GH) 13 (11–14); anterior lateral-line proper (BB’) four; supratemporal (BB) six; and lateral-line proper (BI) 32/35 (19–38), including two to four on caudal-fin base.

Dorsal surface covered by simple, stout spinules, except for eye window, lips, distal fifth of dorsal surface, entire ventral surface of pectoral fin, distal half of dorsal surface, entire ventral surface of pelvic fin, entire anal fin and its base, membranes of dorsal fin, anus, and caudal-fin rays. Narrow band of single row spinules anterior to illicial trough (naked medially in some smaller specimens). Ventral surface covered by slightly shorter, firm spinules (one paratype with scattered spinules centrally on belly). Jaws and body margin along lateral line densely covered with simple, stout cirri; cirri absent from the head, jaws and ventral surface.

Colouration. When freshly dead, many irregular large green spots, some more elongate, on rosy background, 5 bars radiating from eye; ventral surface paler. When preserved, spots deep brown; background light greyish to pale. Mouth cavity, gill chamber and peritoneum pale and unpigmented.

Distribution. Known from the eastern Indian Ocean off Indonesia and western Pacific Ocean off the Philippines. Found at depth between 180 m and 359 m.

Etymology. We are pleased to name this fish after Dr. Martin F. Gomon, Senior Curator of Fishes, Museum Victoria, Melbourne, Australia, for his great contribution to fish taxonomy and for his long-term friendship with the authors.

Comparison. Chaunax gomoni sp. nov. is the only species found to have un-pigmented peritoneum which readily distinguishes it from all known congeners. It is similar to several species in C. abei -group that have spots on dorsal surface, including C. abei Le Danois, 1978 , C. endeavouri Whitley, 1929 , C. breviradius Le Danois, 1978 and C. nudiventer Ho & Shao, 2010 . Although most similar to C. abei and C. endeavouris in having spots of similar size on the dorsal surface, C. gomoni sp. nov. can be distinguished from these two species in having only simple spinules covering the body (vs. bifurcate mixed with simple spinules on dorsal surface). Moreover, it can be distinguished from C. breviradius in having relatively large spots which become larger and more widely spaced with growth (vs. spots uniformly small and dense spots at all sizes) and relatively stout spinules on the body; and from C. nudiventer in having the ventral surface covered by fine spinules (vs. a large naked area on the ventral surface) and relatively few neuromasts in the upper preopercular series (two, vs. three to five), in the pectoral series (11–14, vs. 15–19), and in the pectoral series (29–38, vs. 39–50).

Figures

Fig. 1. Chaunax gomoni sp. nov., holotype, HUMZ 193991, 174 mm SL, fresh colour after freezing. A. lateral view. B. dorsal view. Photo by T. Kawai.

Fig. 2. Chaunax gomoni sp. nov.. A. holotype, HUMZ 193991, 174 mm SL, lateral view, preserved. B. paratype, BMNH 1986.9.29.18, 134 mm SL, dorsal view, preserved. Photo by H.-C. Ho.