Obliquogobius fluvostriatus, Chen & Jaafar & Shao, 2012

Chen, I-Shiung, Jaafar, Zeehan & Shao, Kwang-Tsao, 2012, A new Obliquogobius (Teleostei: Gobiidae) from Kumejima, Ryukyu Islands, Japan, Zootaxa 3367 (1), pp. 269-273 : 270-272

Obliquogobius fluvostriatus n. sp.

( Figs. 1 , 2 )

Material examined. Holotype, NSMT-P102090 , 24.3 mm SL, male, Dredge Station No. 79; Kumejima, Ryukyu Islands, Japan, 26°14.686ʹN, 126°49.623ʹE, 141–165 m depth, Tabata (triangular dredge); 11 Nov. 2009; coll. Y.C. Liao et al.

Diagnosis. Obliquogobius fluvostriatus n. sp. is distinguished from other congeners by the following combination of features: D2 rays I/9; A rays I/10; P rays 21; VC 26; LR 22; TR 7; belly scaled; isthmus, P base, cheek, predorsal region and operculum naked; gill opening very wide, extending forward of the vertical through rear margin of pupil; and specific life colouration as head with vertically infraorbital yellow band; one wide longitudinal yellow band from operculum terminating at posterior end of caudal fin, band increasingly wider, such that posterior half of body completely yellow.

Description. Body proportions listed in Table 1. Body elongate, compressed. Head large (30.1% SL), compressed; snout profile slightly pointed and blunt, snout rather short. Eyes large, dorsal margin prominent; bony interorbital width narrow. Mouth oblique, forms a 45–50° angle to the horizontal, lower jaw terminates at a vertical of through anterior margin of the pupil. Lower jaw prominent; upper and lower jaws with 3–4 rows of conical teeth; outermost row of teeth irregularly arranged; 11–12 teeth on each side of upper jaw approximately four times larger than the rest; vomerine teeth absent; tongue truncate, weakly notched mid-tongue. Anterior naris a short tube, posterior naris as large hole. Gill opening very wide, extends anteroventrally through the rear margin of eye. VC 10 + 16 = 26. Dorsal pterygiophore formula 3/221101/9.

Fins. D1 rays VI; D2 rays I/9; A rays I/10; P rays 21(left); V rays I/5+I/5; C segmented rays 17; C branched rays 13. D1 rays reaching D2 origin when adpressed; D2 rays shorter, not reaching segmented C rays when adpressed. P elliptical and long, rear tip extending posterior to vertical of A origin; A origin inserted into vertical of second element of D2; V rounded and moderately long, reaching genital papillae when adpressed, frenum absent, two sides of V joined together by concave, low connecting membrane, all soft rays of V splits into three branches twice. C asymmetrical with upper half of rays more protruded than those of lower half.

Scales. LS 22; TR 7; PreD 0. Scales on body ctenoid posteriorly and cycloid anteriorly. Belly scaled; isthmus, pectoral fin base, cheek and operculum naked. Middle extension of predorsal region entirely naked. Anterolateral extension of scales on head to above terminal pore ρ of anterior oculoscapular canal, anterodorsal portion of nape partially abraded.

Head lateral-line system. Canals: Oculoscapular canal present: anterior terminal paired pores σ, single interorbital pore λ, single pore κ, paired pores ω, paired postorbital pore α and lateral terminal pore ρ; preopercular canal with three pores as γ, δ and ε.

Sensory papillae: Infraorbital papillae pattern longitudinal: row a short and not reaching vertical midline of eye; row b very short, along the lower margin of orbit, row c extending beyond vertical midline of orbit, row d with densely set papillae, row cp as single papilla, row f as paired papillae.

Colouration in fresh preservative and markings. The following description is based on a photograph taken of a fresh specimen prior to preservation ( Fig. 1 ). Ground colour beige to light gray; infraorbital yellow band about a half of pupil diameter in width, band originating below eye and coursing ventrally and terminates at rear margin of lower jaw, band does not persist in preservative; inverted-triangular grayish black mark obscured under yellow band when live; when preserved, only an inverted-triangular gray mark remains, the broad end originates below eye and the apex terminates at the posterior end of the lower jaw; mark made up of closely-set melanophores; region of snout anterior to aforementioned black mark beige and devoid of melanophores; anterior tips of upper and lower lips light pink; one wide longitudinal yellow band originating at the posterior end of the operculum and courses along mid-flank, terminating at posterior end of caudal fin, band about one pupil width, band increasingly widens such that posterior half of body is uniformly yellow; band immediately decreases in width at the origin of caudal fin, covering only lower two-thirds of C region; upper third of C dusky, due to random small black spots on fin membrane; yellow longitudinal band does not persist in preservative; lower two-third of C hyaline in preservative; D1 slightly damaged but some melanophores observed distally; D2 hyaline with thin longitudinal yellow stripe at base, stripe does not persist in long preservative; P, V and A hyaline.

Distribution. This species is only known from Kumejima, Ryukyu Islands, Japan.

Etymology. The specific name, fulvostriatus , is derived from the longitudinal yellow band (in Latin: “ fulvo + striata ”) on the trunk, a conspicuous character in the fresh specimen.

Remarks. Obliquogobius fulvostriatus n. sp. and O. megalops Shibukawa & Aonuma, 2007 , have wide gill openings and a low connecting membrane between the pelvic fins versus narrower gill openings and the pelvic fins completely united in congeners. However, O. fulvostriatus n. sp. can be differentiated from O. megalops by these characters: D2 rays I/9, A rays I/10, P rays 21 (vs. D2 rays I/8, A rays I/9, P rays 23); black T-shaped mark absent from C base (vs. present); and dark markings absent from the body in the preserved specimen (vs. 5 narrow vertical black bars in preserved specimens).

Figures

FIGURE 1. Obliquogobius fulvostriatus n. sp., holotype, NSMT-P102090, 24.3 mm SL, 141–165 m depth, Kumejima, Ryukyu Islands, Japan. Photograph by S.H. Su.

FIGURE 2. Head lateral-line system of Obliquogobius fulvostriatus n. sp., holotype, NSMT-P102090, 24.3 mm SL. Scale = 1 mm. The arrow indicates the ventral extent of gill opening. Abbreviations: AN and PN = anterior and posterior nares, respectively; GOP = anteroventral extension of gill opening. Illustration by I-Shiung Chen.