Taenioides snyderi Jordan et Hubbs, 1925

Koreeda, Reo, Ho, Hsuan-Cing & Motomura, Hiroyuki, 2022, Records of the eel-goby, Taenioides snyderi (Actinopterygii: Gobiiformes: Gobiidae), from Taiwan, Acta Ichthyologica et Piscatoria 52 (2), pp. 167-172 : 167

Taenioides snyderi Jordan et Hubbs, 1925

Figs 1 , 2

Material examined.

NMMB-P5491, male, 150.7 mm SL, Chiayi, Taiwan, bottom trawl, 30 Aug. 1965 ; NMMB-P 6090, 137.1 mm SL, Anping Fishing Harbor , Tainan, bottom trawl, 23 Mar. 2003 ; NMMB-P32256, 2 specimens, 156.8-160.9 mm SL, off mouth of Tseng-Wen River , Tainan, Taiwan, 4 Apr. 1995 .

Description.

Counts and measurements are shown in Tables 1 and 2 and Fig. 3 . Body elongated, subcylindrical, compressed posteriorly. Head slightly depressed. Snout longer than interorbital space. Eye small, embedded in anterodorsal head. Anterior nostril just behind upper lip, with short tube, reaching to or slightly over (NMMB-P 32256) upper lip. Posterior nostril in front of eye, forming oblique crest, size similar to eye diameter. Mouth terminal, forming angle of 60° with body axis, gape relatively wide; maxilla extending posteriorly to slightly in front of eye; upper lip well developed below anterior nostril, extending posteriorly with small flap-like projections; lower lip covering posteroventral margin of lower jaw, smaller than upper lip, smooth. Gill opening narrow, extending from behind posterior margin of preopercle to just below upper part of pectoral-fin base. Anus located at anterior one-third of body.

Sensory canals and pores absent. Three paired slender barbels on chin surface to lower margin of mandible; anteriormost pair on tip of chin; middle pair midway along lower jaw; posteriormost pair slightly before mouth corner. Dermal folds with single row of sensory papillae on head and body (damaged in some areas on specimens, especially NMMB-P 6090); row 14 well developed, extending slightly below row 9 (Fig. 2 ); row 17 comprising two transverse rows, the anterior row the longer (Fig. 2 ); anteriormost low lv located on anterolateral trunk.

First and second dorsal fins connected by membrane; all first dorsal-fin spines flexible; all second dorsal-fin rays segmented; second dorsal fin continuous with caudal fin, with distinct notch between them. All anal-fin rays segmented, height subequal to second dorsal fin, continuous with caudal fin with distinct notch between them. Pectoral fin rounded, just behind gill opening, less than half length of pelvic fin; all rays segmented and branched (except upper and lowermost); free ray absent. Pelvic-fin origin below pectoral-fin base, posterior end reaching midway along trunk; spine covered with skin; all soft rays branched and segmented; fifth soft ray longest, anterior half connected by membrane to adjacent ray; left and right fins connected by membrane; pelvic frenum present, smooth with slightly concave posterior margin; half length of longest ray fused to abdomen by membrane; posterior margin of membrane between pelvic fin and abdomen located slightly behind anteriormost sensory papillae row lv. Caudal fin pointed, slightly shorter than pelvic fin.

Scales absent. Teeth in each jaw flat, conical, outer teeth larger than inner teeth; upper jaw with 10-16 slender outer teeth, distributed irregularly almost across entire jaw edge; lower jaw with 7-12 outer teeth (slightly longer than upper jaw teeth), distributed over slightly narrower to two-thirds width of jaw edge; inner teeth of each jaw less than one-third length of outer teeth. First hemal spine vertical. Other hemal spines slenderer than first spine, angled posteriorly. Second anal-fin pterygiophore Y-shaped.

Color in alcohol (Fig. 1 ). Body grayish-pink to pale pink, tail brownish. Dorsal fin light grayish-brown to grayish-brown with narrow white subtranslucent margin. Anal fin paler than dorsal fin, light grayish-brown to beige. Pectoral and pelvic fins paler than anal fin, pale beige to beige. Caudal fin darker than dorsal fin, dark yellowish-brown.

Distribution.

Taenioides snyderi has been recorded to date only from southern Japan; Tokyo Bay to Kochi Prefecture (Pacific coast), Fukuoka Prefecture (East China Sea), Seto Inland Sea, Ariake Bay, Yatsushiro Sea, and Kagoshima Bay ( Jordan and Hubbs 1925; Kurita and Yoshino 2012; Koreeda and Motomura 2021). The presently reported specimens, from the western coast of Taiwan, represent the first record outside of Japanese waters.

Remarks.

Identification of examined specimens was based on the following combination of characters, which closely matched the diagnostic features of Taenioides snyderi given by Kurita and Yoshino (2012), Murdy (2018), Kanagawa et al. (2018), and Koreeda and Motomura (2021): total dorsal-fin rays 51-55, total anal-fin rays 44-46, pectoral-fin rays 17-19, vertebrae 10 + 21 = 31, barbel arrangement 2-2-2, sensory papillae row 14 developed and extending just below row 9, row 17 comprising two transverse rows, pelvic-fin base fused to the abdomen by a membrane to anteriormost sensory papillae row lv (half-length of pelvic fin), and brownish second dorsal fin with narrow white subtranslucent margin.

The pelvic-fin posterior end to anus (P-A) length/head length of the Taiwanese specimens of T. snyderi was less than 65.6%, being slightly shorter than in Japanese specimens (Fig. 3 ). The proportion is variable depending on the degree of fusion of the pelvic fin to the abdomen. Koreeda and Motomura (2021) reported that the pelvic-fin base of T. snyderi from southern Japan was strongly fused to the abdomen by a membrane, the posterior end of the base being located below the anteriormost sensory papillae row lv. In the Taiwanese specimens, the pelvic-fin base fusion extended slightly behind the anteriormost row lv. The significance of this difference remains unclear.

Figures

Figure 1. Preserved specimens of Taenioides snyderi from Taiwan. A: NMMB-P 5491, male, 150.7 mm SL, Chiayi; B: one of NMMB-P 32256, male, 156.8 mm SL, Zengwen River; C: one of NMMB-P 32256, female, 160.9 mm SL, Zengwen River.

Figure 2. Head view of Taenioides snyderi from Taiwan, showing sensory papillae rows on the dermal fold (individual papillae indicated by yellow spots). White arrows indicate posterior end of pelvic-fin base. A: NMMB-P 5491, 150.7 mm SL, Chiayi; B: one of NMMB-P 32256, 156.8 mm SL, Zengwen River; C: one of NMMB-P 32256, 160.9 mm SL, Zengwen River.

Figure 3. Relations of P-A length (A), as % of head length (mm), and P-A length (B), head length (C), Pre-anal length (D), predorsal-fin length (E), and preanal-fin length (F) as % of standard length [mm] of Taenioides anguillaris and T. snyderi. Closed red circles: Taenioides snyderi (Taiwan); open red circles: T. snyderi (Japan); blue triangles: T. anguillaris (Japan). Data for T. anguillaris and T. snyderi from Koreeda and Motomura (2021) and Miyahira and Tachihara (2022).