Gymnothorax cinerascens ( Rüppell 1830 )

Smith, David G., Bogorodsky, Sergey V., Mal, Ahmad O. & Alpermann, Tilman J., 2019, Review of the moray eels (Anguilliformes: Muraenidae) of the Red Sea, with description of a new species, Zootaxa 4704 (1), pp. 1-87 : 22-25

Gymnothorax cinerascens ( Rüppell 1830) —Plain Moray

( Figures 11 , 12 , 19 , 20 )

Muraena cinerascens Rüppell 1830: 120 ( Mohila , Red Sea). Holotype (unique), SMF 3486 .

Gymnothorax hepatica: Bamber 1915: 478 (part?).

Gymnothorax hepaticus (non Rüppell): Clark et al. 1968: 21 (part?); Goren & Dor 1994: 7 (part?); Randall & Golani 1995: 859, fig. 3; Golani & Bogorodsky 2010: 10 (part?); Golani & Fricke 2018: 21 (part?).

Lycodontis hepaticus: Dor 1984: 28 (part?).

Gymnothorax monochrous (non Bleeker): Khalaf 2004: 36 (part?).

Red Sea material. Red Sea: SMF 3486 (1, 475, holotype) ; SMF185 (2 of 3, 176–253). Egypt : USNM 166913 (1, 445), Ghardaqa (Hurghada) . Sudan: BPBM 20758 (3, 225–385), Suakin Archipelago . Saudi Arabia: KAUMM 395 [ KAU12-290 ] (1, 603), Farasan Archipelago ; KAUMM 396 [ KAU13-643 ] (1, 376), Al Khoreybah ; KAUMM 397 ( KAU13-116 ) (1, 755), Al Wajh bank ; SMF 185 (2 of originally 3, 178–253), Al Muwaylih ; SMF 35808 [ KAU12-016 ] (1, 675), Farasan Archipelago ; SMF 35809 [ KAU12-247 ] (1, 234), Farasan Archipelago ; SMF 35810 [ KAU12-416 ] (1, 890), Farasan Archipelago ; SMF 35828 [ KAU12-1085 ] (1, 191), Jeddah , Obhur ; SMF 35875 [ KAU17-157 ] (1, 569), Dumsuk I., 6– 10 m. Eritrea, Dahlak Archipelago : USNM 312570 (1, 496), Difnein Island ; USNM 312571 (4, 309–450), Sciumma Island ; USNM 446881 (16, 221–592), Delemmi ; USNM 312569 (3, 301–795), Melita Bay .

Diagnosis. Moderate-size moray, moderate in length and depth, tail relatively slender, head behind eye slightly elevated. Preanal length 2.0– 2.2 in TL. Third intermaxillary tooth close to vertical at anterior margin of eye. Vomerine teeth biserial in adults. Head and body plain brown without markings; margin of dorsal and anal fins yellowish to yellow at tip of tail. Vertebrae 5–6 / 55–57 / 128–135.

Description. In TL: preanal length 2.0–2.2, predorsal length 7.5–10.4, head length 6.2–8.1, body depth at anus 15–23. In head length: snout length 5.3–6.6, eye diameter 8.6–13.8, upper-jaw length 2.2–3.6. Pores: LL 2, SO 3, IO 4, POM 6. Vertebrae: predorsal 5–6, preanal 55–57, total 128–135.

Body moderately elongate; anus at or slightly before midlength; dorsal-fin origin before gill opening; height of dorsal fin about one-third body depth. Jaws slender, of equal length, may be slightly hooked. Eye moderate, over middle of upper jaw. Anterior nostril tubular; posterior nostril with a raised rim, above anterior margin of eye. Third infraorbital pore slightly behind level of anterior margin of eye.

Teeth smooth, slender and pointed or blade-like. Intermaxillary teeth long and slender, in a single peripheral series, 3–6 on each side sometimes with a few much smaller teeth between; three slender, depressible median teeth; third intermaxillary tooth close to vertical through anterior margin of eye, ratio between distance from third intermaxillary tooth to tip of snout and distance from same tooth to anterior margin of eye 3.2–12.6. Maxilla with about 10–18 triangular teeth in a single row in large adults, smaller specimens with 1–3 larger inner teeth anteriorly. Dentary with 1–4 larger inner teeth and about 12–22 smaller outer teeth. Vomerine teeth biserial in adults, uniserial in young.

Color: body and fins dark brown, fins with yellow margin at tip of tail, yellowish or yellow more obscure with growth. Throat grooves darker brown. Head pores with a narrow dark margin. Iris in life reddish brown. Some smaller specimens light grayish brown with scattered dark markings.

Maximum size at least 890 mm.

Distribution and habitat. Known with certainty only from the Red Sea, where it occurs primarily in turbid, silty water, on dead reefs, and in sheltered areas at depths of 1– 20 m. More common in the southern part of the Red Sea than in the north.

Remarks. This species has long been considered a synonym of Muraena hepatica Rüppell , but our studies indicate that it is distinct, based on both morphological and genetic characters. The holotype of M. cinerascens actually belongs to the species most commonly reported as Gymnothorax hepaticus . The true G. hepaticus has been redefined; see the account of that species for a more detailed explanation of the differences between the two species. Two of the specimens, SMF 35828 and SMF 35875 differ somewhat in their color pattern from the others ( Fig. 12 ). In preservative, they are medium brownish gray with scattered black markings. In life, SMF 35828 is pale brown speckled with dark brown, with edge of fins pale yellow. The live colors of SMF 35875 were not recorded, but it belongs to the same COI lineage as the other specimens of G. cinerascens (see Fig. 48 ), and we treat it here as an aberrant color pattern of that species. SMF 35828 was not tissue-sampled, but it agrees in most other characters, and we are placing it in this species. The specimens in SMF 185 were originally labeled as syntypes of Muraena cinerascens , but Böhlke & Smith (2002) showed that they are not. They were listed by Rüppell (1852) as Muraena cinerascens var. umbrina but without a description or a reference to a description, leaving the name as a nomen nudum, hence unavailable. SMF 185 contains three specimens; two of them are G. cinerascens and one is G. hepaticus (now SMF 35879).

For the phylogenetic analysis, no sequences of G. hepaticus from other regions could be identified. The four sequences from the Red Sea showed very little variation and the next closely related species are G. fimbriatus (Bennett) and an undescribed species of Gymnothorax with collection locality Red Sea ( Israel, Gymnothorax sp. 5), with which G. hepaticus was placed on a joint branch with moderately high bootstrap support.

Previous records of Gymnothorax hepaticus in the Red Sea undoubtedly include G. cinerascens . These specimens would have to be re-examined to determine their true identity. We can confirm that BPBM 20758 belongs to G. cinerascens because Randall & Golani (1995, Fig. 3 ) included a photograph of one of the specimens. It appears to be more common than the true G. hepaticus . It is uncertain whether it occurs outside the Red Sea.

Gymnothorax cinerascens has rarely been mentioned in the literature. Klunzinger (1871: 615) included it (as Muraena cinerascens ) as a synonym of Muraena undulata , although he suggested that it might be a separate species. However, he described it as having broad crossbands (“ Körper mit breiten Querbändern”), and it is obviously not Rüppell’s species.

Figures

FIGURE 3. Echidna nebulosa. A: Dahab, Egypt; B: Dahab, Egypt. Photos by S.V. Bogorodsky.

FIGURE 11. Gymnothorax cinerascens. A: Dumsuk I., Farasan Archipelago, Saudi Arabia; B: KAUMM 397 [KAU13-116], 755 mm TL, Al Wajh bank, Saudi Arabia. Photos by S.V. Bogorodsky.

FIGURE 12. Gymnothorax cinerascens, SMF 35828 [KAU12-1085], 191 mm TL, Obhur, Jeddah, Saudi Arabia. A: drawing of upper jaw; B: drawing of head close-up; C: alive. Drawings by D.G. Smith, photo by S.V. Bogorodsky.

FIGURE 19. Gymnothorax cinerascens (A, C, E) and G. hepaticus (B, D, F). A: SMF 3486, 475 mm TL, holotype, Red Sea; B: SMF 3554, 535 mm TL, holotype, Red Sea; C & D: drawing of the head showing cephalic sensory system and position of third intermaxillary tooth and IO pore; E & F: drawing of the dentition on the upper jaw. Photos by S. Traenkner (A & B), drawings by D.G. Smith.

FIGURE 20. Relationship of two characters to TL. A: preanal distance to TL; B: ratio between distances “third intermaxillary tooth-tip of snout” and “third intermaxillary tooth-vertical at anterior margin of eye” to TL. Open circle- G. cinerascens, solid circle- G. hepaticus. Drawing by T.J. Alpermann.

FIGURE 48. Unrooted maximum likelihood phylogeny of Indo-Pacific moray eels (Muraenidae) based on partial mitochondrial COI. Branch support values were obtained by 100 bootstrapped replicates; only bootstrap values above 50 percent are shown. The scale bar represents average number of nucleotide substitutions. (A) = specimen sequenced in this study; (B) = sequence retrieved from BOLD; (C) sequence retrieved from CRIOBE; (G) = sequence retrieved from GenBank; (R) = sequence retrieved from Reece et al. (2010); (ID) = species ID re-assigned herein; (ID-H) = specimen re-assigned as of Huang et al. (2019); (SAU) = collected in Saudi Arabia; (ISR) = collected in Israel.