Gymnothorax nudivomer ( Guenther , 1867)

Cabebe-Barnuevo, Roxanne A., Obar, El Andro A., Penuela, Dianne Frances A., Motomura, Hiroyuki, Babaran, Ricardo P. & Malay, Maria Celia D., 2023, Two new records of moray eels representing genera Gymnothorax and Strophidon (Actinopterygii: Anguilliformes: Muraenidae) from the Philippines, Acta Ichthyologica et Piscatoria 53, pp. 217-226 : 217

Gymnothorax nudivomer ( Guenther, 1867)

English common name: yellowmouth moray (Fig. 3

Material examined.

UPVMI-03157, 619 mm TL, Iloilo Fish Port Complex (IFPC), Iloilo City, Panay Island, Philippines, 8 June 2022, R. Cabebe-Barnuevo and R.P. Babaran leg.

Morphological diagnosis and description.

Body elongated, large; tapering towards caudal area. Head large; eyes moderate in size, and situated slightly closer to snout (19% of HL) than rear of lower jaw (22% of HL, see Table 1 ). Mouth large; snout short and blunt; anterior nostril short, tubular, and located at snout tip; posterior nostril large, elliptic, and located above and before anterior margin of eye; upper and lower jaws subequal; teeth not visible when mouth closed; teeth on both jaws uniserial, sharply pointed; anterior teeth large and triangular; posterior teeth short and serrated. Dorsal-fin base very long; its origin anterior to gill opening. Anal-fin base shorter; its origin just behind anus. Caudal fin confluent with dorsal and anal fins. Pectoral and pelvic fins absent. Gill opening moderately large and elongated; located on middle side of body. Anus moderate in size, circular, and positioned anterior to midpoint of body. Supraorbital pores 3: first pore located on snout tip, small and circular; second pore located above anterior nostril, largest in size, circular; third located above first infraorbital pore, equal in size with first pore, circular. Infraorbital pores 4, along upper jaw; first pore located below base of anterior nostril; second pore between anterior nostril and anterior margin of eye; third pore before anterior margin of eye; fourth pore located beyond posterior margin of eye. Preoperculo-mandibular pores 6, along lower jaw; all pores positioned anterior to rictus. Branchial pore 1, located along posterodorsal head anterior to gill opening, posterior to dorsal-fin origin. Teeth pointed and uniserial; intermaxillary teeth 7; median intermaxillary teeth 1; vomerine teeth absent.

Fresh coloration.

Body yellow to light brown, becoming darker on caudal area; covered entirely with white spots of varying sizes; white spots on head and anterior body area very small, becoming large towards caudal area; white spots on dorsal and anal fins similar in body spots; white spots on caudal area composed of both rounded and irregular in shape; posterior margin of caudal fin white; eyes with vertical black bar; inner mouth bright yellow; gill opening black.

Color of preserved specimen.

Body light brown, becoming darker on caudal area; white spots still visible; posterior margin of caudal fin white; inner mouth white; gill opening black.

Distribution.

Widely distributed across the Indo-Pacific Ocean. Specific reports are summarized in Table 2 .

DNA Barcode.

A COI sequence fragment measuring 605 basepairs (bp) was submitted to GenBank under accession number OR214978.

Remarks.

Gymnothorax nudivomer was originally described as Muraena nudivomer from the Zanzibar Archipelago by Günther ( Playfair and Günther 1867). It was then widely reported as G. nudivomer distributed across the Indo-Pacific Ocean at depths of 2-271 m ( Mundy 2005; Fricke et al. 2009). This species can reach up to 1800 mm in length ( Böhlke and Randall 2000). In Böhlke et al. (1999), G. nudivomer was listed as one of the moray eels occurring within the western central Pacific but it was not stated if the species was collected specifically within Philippine waters. Furthermore, according to the list of reef fishes by Allen and Erdmann (2012) from the East Indies (which includes the countries of Myanmar, Thailand, Indonesia, Singapore, Malaysia, Brunei, Papua New Guinea, Solomon Islands, and the Philippines), G. nudivomer was not known to exist in the country. Finally, Herre (1953) provided a list of approximately 2145 Philippine species, however, this species was not among them. Hence, the presently reported study treats the specimen collected from Iloilo as the first report (new country record) from Philippine waters. Table 2 and Figs 1 , 2 provide the geographic distribution of the species while Table 3 includes other species within the genus Gymnothorax reported in the country. Reports that did not clearly specify that the data collection occurred within the Philippines have been excluded from the list.

This fish is commonly known as the yellowmouth moray and can be easily identified by its tapering body form, white spots scattered throughout the body, and yellow coloration inside the mouth. Gymnothorax elegans and G. nudivomer are closely related species ( Smith et al. 2019), but can easily be distinguished based on their color patterns. Gymnothorax elegans Bliss, 1883 has larger and distinct patterns of white markings throughout the body that forms into bars towards the caudal fin (i.e., fig. 13, Smith et al. 2019), in contrast to G. nudivomer , which has relatively smaller, rounded spots on the body, that becomes a larger and elongated circle towards the caudal fin (i.e., Fig. 3 , this publication; fig. 24, Smith et al. 2019).

Family Muraenidae Rafinesque, 1810

Genus Strophidon McClelland, 1844

Figures

Figure 1. Global geographic distribution of Gymnothorax nudivomer (red star) and Strophidon dorsalis (green star).

Figure 2. Geographic distribution of Gymnothorax nudivomer (red dot) and Strophidon dorsalis (green dot) in Western Visayas, Philippines (the inset to Fig. 1)

Figure 3. Gymnothorax nudivomer, UPVMI- 03157, 619 mm TL, Iloilo Fish Port Complex (IFPC), Iloilo City, Philippines.