Gymnothorax pharaonis, Smith & Bogorodsky & Mal & Alpermann, 2019

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 : 41-45

Gymnothorax pharaonis n. sp. —Pharaoh’s Moray

( Figures 25–29 )

? Muraena undulata: Klunzinger 1871: 615 (Quseir, Egypt).

? Gymnothorax meleagris (non Shaw & Nodder): Fowler & Steinitz 1956: 270 (Eilat).

Gymnothorax undulatus (non Lacepède): Randall & Golani 1995 (in part, Pl. 1F, Fig. 6 ).

Holotype. SMF 35814 [ KAU13-614 ] (322), Red Sea , Saudi Arabia, Al Khoraybah, Yabua Island, isolated coral block on slope, 27°47’24.66” N, 35°07’48.00’’ E, 14–16 m, 23 Jun. 2013, S.V. Bogorodsky.

Paratypes. Israel: BPBM 31848 (1, 475), Gulf of Aqaba, Eilat, North Beach , mooring, 7 m, 11 Nov. 1986, J.E. Randall . Egypt: BPBM 18265 (2, 270–284), S end of Sinai Peninsula, Sharm-el-Moya , reef, 15 m, 21 Sep 1974, J.E. Randall and A. Levy ; BPBM 19805 (1, 331), Ras Muhammad, S tip of Sinai Peninsula, reef front in 4–6 m, 26 Oct. 1975, J.E. Randall et al .; BPBM 20825 (1, 277), Gulf of Aqaba , 7 km S of Nuweiba, A. Ben-Tuvia, 3 Aug. 1976 ; USNM 262775 (1, 305 mm TL), NW coast Gulf of Aqaba, Bay at El Himeira, 0–18 m, 16 July 1969, V.G. Springer et al .; USNM 312604 (6, 133–380), Gulf of Aqaba, Bay Between Marsa Mokrakh and El Himeira , NW Coast, 0–3 m, 15 July 1969, V.G. Springer et al .; USNM 312605 (4, 187–228), NW Gulf of Aqaba, Ras Burqa , 9–15 m, 21 July 1969, V.G. Springer et al .; USNM 312609 (3, 303–419), Strait of Jubal S end of Sinai Peninsula at Ras Muhammad , 0–9 m, 26 Sep 1969, V.G. Springer et al .; USNM 405385 (4, 233–260), NW coast of Gulf of Aqaba, reef near road at Marsa Muqabila , 0–2 m, 29 July 1969, V.G. Springer et al .; USNM 410185 (7, 123–227), same data as USNM 312604 ; USNM 410188 (4, 223–299), same data as USNM 262775 ; USNM 410628 (1, 310), Gulf of Aqaba, Dahab, Lighthouse , 18 m, 25 Nov. 2011, S.V. Bogorodsky . Sudan: BPBM 19733 (1, 156), 1 mile N of Port Sudan , reef flat in 0.5–1.0 m, 9 Oct 1975, J.E. Randall . Saudi Arabia: KAUMM 400 [ KAU12-1059 ] (1, 225), Al Lith , 8 Mar. 2012, T.J. Alpermann & S.V. Bogorodsky ; KAUMM 401 [ KAU13-286 ] (1, 145), 50 km south of Al Wajh , fringing reef of seaward reef, 8–12 m, 13 Jun. 2013 ; KAUMM 402 [ KAU13-615 ] (1, 224), same data as holotype ; SMF 33617 (1, 49), Al Wajh, Rykhah Is , 10 Apr. 2011, S.V. Bogorodsky ; SMF 33618 (1, 78), Al Lith , 30 Mar. 2011, T.J. Alpermann & S.V. Bogorodsky ; SMF 35815 [ KAU12-1028 ] (1, 182), Al Lith , 9 m, 7 Mar. 2012, T.J. Alpermann & S.V. Bogorodsky ; SMF 35816 [ KAU12-1060 ] (1, 208), Al Lith , 8 Mar. 2012, T.J. Alpermann & S.V. Bogorodsky .

Non-type material (detailed counts and measurements not taken). KAUMM 403 [ KAU14-818 ] (1, 125), Al Lith , 6–8 m, 16 Nov 2014, T.J. Alpermann & S.V. Bogorodsky ; KAUMM 404 [ KAU14-1011 ] (1, 246), Al Lith , 8–10 m, 19 Nov 2014, T.J. Alpermann & S.V. Bogorodsky ; SMF 35817 [ KAU14-928 ] (1, 213), Al Lith , 6–9 m, 18 Nov. 2014, T.J. Alpermann & S.V. Bogorodsky ; USNM 312606 (4, 62–140) , Egypt, NW Coast, Gulf of Aqaba , about 1 Mile North of Ras Burqa, 21 July 1969 ; USNM 312607 (12, 49–160) , Egypt, just N of Ras Burqa , Gulf of Aqaba, NW Coast, 23 July 1969, V. G. Springer et al .; USNM 313223 (9, 64–96) , Egypt, Gulf of Aqaba , Bay at El Himeira, 8 Sept. 1969, V. G. Springer et al .; USNM 410183 (28, 50–192) , same data as USNM 262775 ; USNM 410184 (14, 56–265) , same data as USNM 312604 ; USNM 410186 (17, 77–280) , same data as USNM 312609 ; USNM 410187 (28, 75–225) , same data as USNM 405385 ; USNM 410189 (1, 227) , same data as USNM 262775 (cleared and stained).

Diagnosis. Small to medium-size moray with slender head and jaws. Teeth sharp, slender, and smooth; intermaxillary teeth in one peripheral and one medial series; maxillary teeth in two rows, an outer row of 14–20 small teeth, and an inner row of 0–6 large, depressible teeth; dentary teeth in one row, with two large fixed teeth at anterior end, followed by a single row of 15–20 small teeth, and one large, depressible tooth just behind the large anterior teeth. Color brown with irregular dendritic pale markings, not interconnected or chain-like; oblique, conspicuous, parallel streaks present in dorsal fin (on tail). Total vertebrae 123–128.

Description (data for the holotype first, for paratypes in parentheses). In TL: preanal length 2.3 (2.2–2.4), predorsal length 9.0 (7.7–10), head length 7.8 (7.0–8.4), body depth at gill opening 19 (15–28), depth at anus 23 (17–28). In head length: snout length 5.2 (4.9–7.1), eye diameter 8.7 (7.6–11), upper-jaw length 2.3 (2.3–3.1). Predorsal vertebrae 8 (5–8), preanal vertebrae 48 (47–50), total vertebrae 125 (123–128).

A small to medium-sized moray eel, moderately elongate, with the anus slightly anterior to midlength. Dorsal and anal fins continuous with caudal fin, anal fin beginning immediately behind anus, dorsal fin beginning anterior to gill opening. Jaws and snout moderately slender, edges usually straight, concealing teeth when closed, but sometimes slightly arched in larger specimens; upper and lower jaws nearly equal in length. Gill opening small and pore-like, on side of head slightly below lateral midline. Anterior nostril tubular, relatively long, reaching slightly beyond edge of lip when depressed. Posterior nostril a broadly oval opening, without a conspicuous raised rim, above anterior part of eye, at a point where a horizontal line drawn from dorsal edge of eye would meet a vertical line drawn from anterior edge of eye.

Lateral line with two small, inconspicuous pores at anterior end of canal, approximately under dorsal-fin origin; second pore closer to first pore than to gill opening ( Fig. 25 ). Preoperculo-mandibular canal with six pores, all of them along lower jaw: the first and smallest located at the anterior tip of jaw, the second below and behind that, the remaining four pores extending in a line posteriorly to a point slightly anterior to rictus. Infraorbital canal with four pores: the first slightly below and behind base of anterior nostril, the second about a third of the way to eye, the third just anterior to eye, and the fourth under posterior margin of eye. Supraorbital series with three pores: the first and smallest at tip of snout just above edge of lip, the second slightly above anterior edge of base of anterior nostril, the third on top of snout directly above second infraorbital pore. No pores in supratemporal canal.

Teeth slender, sharp, and smooth, without any serrations ( Fig. 26 ). Intermaxillary teeth large, conical, sharply pointed; peripheral series with about 8–14 teeth, the anteriormost teeth smallest, increasing in size posteriorly; two or three median teeth, long, extremely sharp and depressible. Maxillary teeth in one or two rows: the inner row with 0–6 long, sharp, widely separated, depressible teeth at anterior end, the outer row with about 13–20 much smaller, fixed, triangular, recurved teeth, smallest at anterior end of row, increasing in size posteriorly to a point approximately under eye, then decreasing in size again posteriorly. Lower jaw with two large, fixed teeth at anterior end, followed by approximately 15–25 much smaller, triangular, recurved teeth; directly behind the two large anterior teeth is an even larger, depressible tooth just inside the row of smaller teeth. Approximately 3–9 very small vomerine teeth, in a single row, partly hidden in the folds of skin in roof of mouth.

Color: in adults, ground color medium to dark brown with irregular, dendritic, pale markings, variable in size and form ( Figs. 27 & 28 ). The most common form is short, broadly linear, vermicular lines or spots, sometimes expanded into snowflake-like blotches, but not interconnected or reticulated. On tail, the spots often line up to form oblique streaks extending onto dorsal fin. Markings sometimes become smaller and more closely spaced anteriorly. Fins with a narrow white edge, but this often not conspicuous. Grooves on throat as dark streaks. An inconspicuous pale stripe usually present on dorsal midline of snout. Corner of mouth dark. Posterior nostril and pores usually edged in dark brown. Juveniles uniform brown with lower jaw and throat pale ( Fig. 29 ).

Size and development. This is a relatively small species, the largest specimen examined was 475 mm TL, but only one other specimen was greater than 400 mm and only three over 300 mm. Females with large eggs were found in specimens as small as 223 mm. Males appear to mature at larger sizes than females; two that were clearly males were among the largest specimens examined, 299 and 419 mm. Females were measured at 380, 325, and 305 mm. There is some evidence of sexual dimorphism in dentition. The two males mentioned above lack the inner maxillary teeth; they also have fewer dentary teeth (14 vs. 18–26 in females).

Small juveniles of this species are uniform brown with a conspicuous white lower jaw ( Fig. 29A ). At about 50 mm, pale spots begin to develop behind the head. As the eel grows, the spots progress posteriorly and become larger and more conspicuous, eventually assuming the dendritic pattern characteristic of adults ( Fig. 29B ). With growth, the pale lower jaw becomes less distinct.

Variation. The specimens collected and examined were all brown with pale markings. The relative extent of pale and dark areas varies considerably among individuals, however. In most cases, the dark areas are more extensive, giving the fish a brown appearance, but occasionally the pale areas prevail. In such cases, the eel may appear pale with brown markings. In most specimens, the pale and dark markings are relatively large, but in others the markings are smaller and more scattered, giving a vermiculated appearance. In some specimens, the markings are larger posteriorly and smaller anteriorly. In larger specimens, the jaws can become arched, leaving the teeth visible when the mouth is closed. This approaches the condition seen in Enchelycore , but the dentition of Enchelycore is quite different ( Smith et al. 2008: 68).

Distribution and habitat. Known from the Red Sea, where it is common in shallow water, but also collected by the second author from Socotra Island outside the Gulf of Aden ( Zajonz et al. 2019, listed as G. cf chilospilus Bleeker 1864 ). Typical habitats are crevices and shelters of fringing seaward reefs, observed from depths of 2– 30 m. May be seen out of shelter at night only.

Etymology. Named for the pharaohs, the rulers of ancient Egypt, whose realm included the Red Sea. Referring also to the regal appearance of this handsomely marked fish.

Remarks. This species has been confused with Gymnothorax undulatus . Like G. pharaonis , G. undulatus has pale markings on a dark background, but in G. undulatus the markings are generally interconnected in a reticulated or chain-like pattern, whereas in G. pharaonis the markings are separate. At larger sizes, G. undulatus has a distinct yellowish-green color on the head in life, which is never found in G. pharaonis . Gymnothorax undulatus is a much larger species, growing to well over 1 m in length. Mature G. pharaonis can be found at lengths less than 300 mm, a size at which G. undulatus is still immature. The two species also differ in the number of vertebrae, 122–128 in G. pharaonis vs. 126–138 in G. undulatus . Gymnothorax pharaonis also resembles G. baranesi , but in that species the pale markings on the body are more like snowflakes or rosettes. On the tail, the markings on G. baranesi are in the form of discrete spots rather than the oblique streaks found in G. pharaonis . In addition, G. baranesi has more vertebrae, 137–142. Gymnothorax pharaonis most closely resembles and is closest genetically ( Fig. 48 ) to G. margaritophorus Bleeker , which is widely distributed in the Indo-Pacific but does not occur in the Red Sea. The latter is also a small species, brown with pale markings and a pale stripe on the top of the snout. It has horizontal dark streaks behind the eye, however, which are lacking in G. pharaonis , and it has more vertebrae (127–134). Pale individuals (e. g. from Dahab, Fig. 28B ) may be confused with G. chilospilus Bleeker , but the latter species almost always has a distinctive pale spot at the corner of the lower jaw, which is lacking or not obvious in G. pharaonis . As in G. griseus and G. thyrsoideus , no reciprocal monophyly has yet evolved in the species pair G. pharaonis and G. margaritophorus . The closest relative to this pair of sibling species cannot be identified with high confidence from the present phylogeny, however, it is evident that the two species form part of a highly supported group of taxa to which another Red Sea species belongs, G. johnsoni ( Fig. 48 ).

Figures

FIGURE 6. Enchelycore schismatorhynchus. A: USNM 312174, 514 mm TL, preserved, Cargados Carajos Shoals; B: BPBM 23335, 502 mm TL, fresh specimen, Taiwan. Photos by D.G. Smith (A), J.E. Randall (B).

FIGURE 25. Gymnothorax pharaonis n. sp., drawing of the head showing cephalic sensory system. Drawing by D.G. Smith.

FIGURE 26. Gymnothorax pharaonis n. sp., drawing of the dentition. A: male; B: female. Drawing by D.G. Smith.

FIGURE 27. Gymnothorax pharaonis n. sp., SMF 35814 [KAU13-614], holotype, 322 mm TL, Yabua I., Al Khoraybah, Saudi Arabia. Photo by S.V. Bogorodsky.

FIGURE 28. Gymnothorax pharaonis n. sp. A: KAUMM 400 [KAU12-1059], paratype, 225 mm TL, Al Lith, Saudi Arabia; B: Ras Abu Galum, Egypt. Photos by S.V. Bogorodsky.

FIGURE 29. Gymnothorax pharaonis n. sp., juveniles. A: SMF 33617, 49 mm TL, Al Wajh, Rykhah Is, Saudi Arabia; B: SMF 33618, 78 mm TL, Al Lith, Saudi Arabia. Photos by S.V. Bogorodsky.

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.