Oxycheilinus arenatus (Valenciennes, 1840)

Murugan, Arumugam, Mahadevan, Gopalan & Fricke, Ronald, 2022, First record of the speckled Maori wrasse, Oxycheilinus arenatus (Valenciennes, 1840) (Actinopterygii: Perciformes: Labridae), from Indian coastal waters, Acta Ichthyologica et Piscatoria 52 (2), pp. 135-139 : 135

Oxycheilinus arenatus (Valenciennes, 1840)

Figs 1 , 2 , 3

Cheilinus arenatus Valenciennes, 1840: 101, pl. 397 ( Réunion, western Mascarenes, southwestern Indian Ocean).

Cheilinus notophthalmus Bleeker, 1853: 493 (Jakarta, Java, Indonesia).

Description.

Apart from the presence of the generic characters mentioned above, the specimens are diagnosed by the following characters: Dorsal fin IX, 10-11; anal fin III, 8-9; pelvic-fin rays I, 5; pectoral-fin rays of left and right sides 11/11~12/12 (2 uppermost rays unbranched); caudal-fin rays 13-14 (upper and lower 2 rays unbranched); pored lateral-line scales 22 (13 on anterior lateral line, 9 on posterior lateral line); vertical scale rows 2 + 7; number of scales on black streak 19; pored scales on black streak 8; predorsal scales 6; gill rakers 5 + 6 = 11; branchiostegal rays 5; vertebrae 10 + 12 = 22 (Fig. 2 ). Body elongate, laterally compressed. Snout short, profile moderately rounded. Eye small; pupil slightly elongate. Interorbital space slightly convex, naked. Head and body covered with scales. Predorsal scales reaching anterior end of orbit. Opercular margins scaleless. Last scale of anterior lateral line located just below base of 4th dorsal-fin soft ray. First scale of posterior lateral line located just above base of 2nd anal-fin soft ray. Head laterally compressed, mouth terminal, gape oblique; posterior margin of lower lip extending beyond vertical through that of upper lip; posterior margin of maxilla extending beyond vertical through anterior margin of orbit; teeth in jaws affixed to outer edge of bony ridge; 2 pairs of large, slender, curved canine teeth anteriorly in each jaw; 16-18 small conical teeth fixed posteriorly on each bony plate behind upper- and lower-jaw canine teeth. Tongue slender, rounded, its upper surface covered with small papillae. Gill rakers thick, short, compressed; rakers on upper limb slightly shorter than those on lower limb; gill membranes free from isthmus. Posterior end of pectoral fin not reaching anus. Pelvic-fin origin and dorsal-fin origin almost on same vertical. Caudal fin truncate, with central part of medium edge slightly rounded, and upper and lower rays elongate. 9th dorsal-fin spine and 7th soft dorsal-fin ray longest; 3rd anal-fin spine and 4th soft anal-fin ray longest; 1st pelvic-fin soft ray longest (Table 1 ).

Color.

Upper part of body light red, abdomen white. Sides with mottled pattern reaching from upper side of head to upper back, consisting of small, scattered orange or dark brown spots at low density. Dark vertical black band at center of body extending from posterior margin of eye to caudal-fin base. Small white spots scattered at high density above vertical band. Large black spot on membranes of first four dorsal-fin spines. Membranes between first four dorsal-fin soft rays otherwise pale green, with white lines and irregularly arranged white spots. Membranes between 4-10 dorsal-fin soft rays whitish translucent. Pectoral-fin base bright yellow, fin membranes transparent. Pelvic-fin base and anal-fin membranes white, fins mottled with light red. Medium caudal-fin membranes white-translucent, mottled with light red, upper and lower lobes yellow (Fig. 3 ).

Remarks.

Oxycheilinus arenatus (Valenciennes, 1840), commonly known as speckled Maori wrasse, is known from the Red Sea and the Indo-West Pacific: East Africa, Seychelles, Madagascar, and Mascarenes east to Marshall Islands and Samoa, north to Ryukyu Islands (Japan). Generally, from the conservation point of view, they are considered 'Least concern’ ( Liu and To 2010). In the Red Sea and Indian Ocean, the species was previously recorded from La Réunion ( Valenciennes 1839, as Cheilinus arenatus ; Fricke et al. 2009), Chagos Archipelago ( Winterbottom et al. 1989, as Cheilinus arenatus ), Mauritius ( Günther 1862, as Cheilinus arenatus ), Seychelles ( Smith and Smith 1963, as Cheilinus arenatus ), Maldives ( Randall and Anderson 1993, as Cheilinus arenatus ; Anderson et al. 1998), Mozambique ( Gell and Whittington 2002), Red Sea ( Randall and Khalaf 2003; Golani and Fricke 2018), Madagascar ( Fricke 1999; Fricke et al. 2018). The current findings represent a range extension of ca. 700 km to the northeast of the closest previously known region (Maldives), and the first record of this species from India. Oxycheilinus arenatus is widespread in the Indo-West Pacific and was probably previously overlooked in Indian waters. Apparently, the species is very rare in India.

This species is found in caves of steep outer reef drop-offs from 25 to at least 46 m with rich invertebrate growth such as large gorgonians or soft corals ( Froese and Pauly 2022). It is naturally rare and has been rarely documented due to its cryptic occurrence in deep reefs. The lower extent of the depth distribution range is unknown. The collecting depth of the Indian specimens below 40 m well agrees with the previously known depth range.

Figures

Figure 1. Geographical distribution of Oxycheilinus arenatus in Indian Ocean, (A) New record from Tuticorin, India and (B) Previous records.

Figure 2. Freshly preserved Oxycheilinus arenatus (A) (CASMBAURM / 232116489) and (B) X-ray of the adult Speckled Maori wrasse with 22 vertebrae (10 abdominal + 12 caudal).

Figure 3. Oxycheilinus arenatus (A) collected from Tuticorin, India (CASMBAURM / 232116487); (B) Head; (C) Dorsal fin and (D) Caudal fin.