Oxymetopon compressus Chan, 1966

Ragul, Sivakumar, Mahadevan, Gopalan, Murugan, Arumugam & Fricke, Ronald, 2024, Discovery of a ribbon goby, Oxymetopon compressus (Actinopterygii: Gobiiformes: Microdesmidae) in Indian waters: A new westernmost record for the genus Oxymetopon, Acta Ichthyologica et Piscatoria 54, pp. 125-129 : 125-129

Oxymetopon compressus Chan, 1966

English common name: robust ribbon goby Fig. 1 A – 1 E ; Table 1

Oxymetopon compressus . — Chan (1966): pp. 1–3, fig. 1. — Klausewitz and Condé (1981): pp. 67–76, figs. 5, 5 a, 6, 7, 19 b, tables I and III. — Koeda and Ho (2019): pp. 85–87.

Oxymetopon compressum . — Prokofiev (2016): pp 175–180, figs. 1 c, 2 c, table 1 and 2. — Prokofiev (2020): pp. 115, 116, fig. 1 f.

Material examined.

CASMBAURM / 2312819 , 1 probably female, 94 mm SL (Fig. 1 A – 1 E ), southeast coast of India, off Parangipettai, Mudasal Odai (fish landing center); 11 ° 29 ′ 06 ″ N, 079 ° 46 ′ 28 ″ E; 9 Oct. 2023, S. Ragul leg .

Description.

First dorsal spines VI; second dorsal fin elements I + 29; anal rays I + 29, pelvic rays I + 4; pectoral rays 19; caudal rays 20; predorsal scales 21; gill rakers on 1 st arch 26. Meristics and morphometrics in Table 1 . Body elongate, laterally compressed, maximum depth (below first dorsal fin) 19.1 % of SL, caudal-peduncle depth 9.7 % of SL. Straight frontal profile, upward faced lower and upper jaws, 46.0 % and 41.5 % in HL respectively. A distinct frontal notch present before eye. High dorsal crest (fleshy keel) present. A pair of nasal openings in preorbital region. Mouth oblique, with a single outer row of small, irregular, slightly curved, inward-pointed canine teeth on premaxillary (Fig. 1 E ). Branchiostegal rays 5 / 5. Body with small soft ctenoid scales, nape with cycloid scales. Caudal-fin base completely covered with scales. First dorsal fin low (base length 14.5 % of SL), second ray 13.5 % of SL, connected with second dorsal fin by a low membrane. Second dorsal fin (base length 49.4 % of SL) with fourth ray 10.8 % of SL; anal fin (base length 42.5 % of SL) with third ray 9.2 % of SL. Caudal fin lanceolate, pointed, caudal-fin length 30.3 % of SL. Pectoral fin rounded, its length 13.6 % of SL. Pelvic fin with third ray elongate, pelvic-fin length 14.0 % of SL.

Coloration.

Freshly dead specimen (Fig. 1 A ): Head and body pinkish brown; distinct red blotch on upper base of pectoral fin; crest rimmed with bright red; eye with red blotch each on upper and lower margins (Fig. 1 D ). Three grey-blue iridescent bars traversing eye. Anal fin and lower caudal fin light reddish pink; caudal fin with vertical light orange and pale blue bars. In preserved specimen (Fig. 1 B ), head and body transitioning to yellowish tint, and belly partially whitish. Anal fin darker compared to fresh state, and caudal fin with prominent dark vertical lines.

Habitat.

The robust ribbon goby, Oxymetopon compressus , has been reported from a depth range of 10 to 18 m, predominantly on silty-sand bottoms, positioned at the outer edge of coral reefs ( Prokofiev 2016). The type specimen, as documented by Chan (1966), was collected on a muddy bottom within the depth range of 14 to 16 m.

In contrast, the presently reported specimen was discovered in a novel habitat, ranging from 20 to 25 m in depth. This new location features muddy-silt washed-out bottom sediments along the Parangipettai coast.

Distribution.

Oxymetopon compressus has been known only from the western Pacific, from Hong Kong ( Chan 1966), Japan: Okinawa, Ryukyu Islands ( Ikeda et al. 2000; Akihito et al. 2002), Gulf of Thailand, East Sumatra, Papua New Guinea, Australia: Low Isles, Queensland ( Allen and Erdmann 2012) and Vietnam ( Prokofiev 2016). The presently reported study expands its distribution to the southeast coast of India in the Indian Ocean.

Figures

Figure 1. Oxymetopon compressus (CASMBAURM 2312819) from southeastern India: (A – C) lateral view of (A) fresh, (B) preserved specimen, and (C) radiograph; (D and E) lateral view of head: (D) prominent bright bands and red high crest; (E) prominent small scales and canine teeth. Scales: A and B = 10 mm; D and E = 5 mm.