Gymnothorax angusticauda (Weber & de Beaufort 1916) —Shorttail Moray

(Figure 8)

Muraena (Priodonophis) angusticauda Weber & de Beaufort 1916: 389, fig. 388 (Near Supiori, Schouten Is., Papua New Guinea). Holotype (unique), ZMA 102162.

Gymnothorax angusticauda: Randall & Golani 1995: 854, Pl. 1a; Golani & Bogorodsky 2010: 10; Bogorodsky et al. 2014: 411; Golani & Fricke 2018: 20.

Red Sea material. Egypt: BPBM 19844 (2, 458–503), Nuweiba. Saudi Arabia: SMF 34962 [KAU12-731] (1, 383), Jizan.

Comparative material. Taiwan: USNM 438183 (1, 486); USNM 438650 (1, 547); USNM 439078 (1, 513). Philippines: USNM 408880 (1, 560). Papua New Guinea: ZMA 102.062 (1, 474, holotype).

Description. In TL: preanal length 1.9–2.2, predorsal length 11–13, head length 8.0–9.8, body depth at anus 25–34. In head length: snout length 5.3–7.1, eye diameter 8.8–11, upper-jaw length 2.8–3.5. Pores: LL 2, SO 3, IO 4, POM 6. Vertebrae: predorsal 4, preanal 58–70, total 143–152.

Body moderately elongate; anus near mid-length; dorsal fin begins slightly before gill opening; tail relatively slender. Head and jaws moderate, jaws closing completely. Eye well developed, at about midpoint of upper jaw. Gill opening nearly horizontal, midlateral. Anterior nostril tubular, reaches edge of lip when depressed; posterior nostril oval, with a slightly raised rim, over anterior part of eye.

Teeth conical to narrowly triangular, finely serrate on posterior edge. Upper jaw with about 5 or 6 peripheral intermaxillary teeth, narrowly triangular, retrorse; 0–3 median teeth, conical. Maxillary teeth uniserial, about 7–14, similar in shape to intermaxillary teeth. Dentary teeth uniserial, similar in shape to those in upper jaw, with about 7–19 teeth on each side. Vomer with about 3–6 teeth in a single row.

Color: medium to light brown or tan, snout and lower jaw darker, abdomen sometimes white; head pores in conspicuous white spots, nostrils white; fins with narrow pale edge; iris yellow.

Of the ten known specimens, the largest is 560 mm.

Distribution and habitat. Known from the Red Sea, Taiwan, the Philippines, Indonesia (Bali and Sulawesi), and Papua New Guinea. The two larger specimens from the Red Sea were collected in less than 0.5 m from the fringing reef at Nuweiba. The smaller specimen was captured in a trawl at about 30 m from the southern Saudi Arabia, off Jizan, from a sandy area close to the island. Information on depth and habitat is not available for the Philippine and Indonesian specimens. Fricke (2015) reported an additional specimen collected from a depth of 15 m from Madang, Papua New Guinea.

Remarks. The smallest trawled Red Sea specimen differs from all the other specimens in having the anus slightly behind midlength rather than slightly before. It also has more total vertebrae (152 vs. 143–148) and distinctly more preanal vertebrae (70 vs. 58–60). The other two Red Sea specimens do not differ in these characters from the western Pacific specimens. With the limited material available and without genetic information from other parts of the distribution area, we cannot assess the significance of these distinctions. In the COI-based phylogeny, the species is most closely related to Gymnothorax albimarginatus (Temminck & Schlegel) and an unidentified Gymnothorax species (Gymnothorax sp. 4, BOLD voucher of SBF244-11 collected from Madagascar), with which it forms a well-supported clade.