Echidna nebulosa ( Ahl 1789 )

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 : 9-10

Echidna nebulosa ( Ahl 1789) —Snowflake Moray

( Figure 3 )

Muraena nebulosa Ahl 1789: 7 , pl. 1 (right fig.) (East Indies). No types known to exist, although Fricke (1999: 42) designated the illustrated specimen as the lectotype.— Klunzinger 1871: 21; Borsieri 1904: 218.

Muraena ophis Forsskål, 1775 : xiv. Nomen nudum.

Muraena ophis Rüppell 1830: 116 , pl. 29 (fig. 2) (Red Sea). Holotype (unique): SMF 19. Objectively invalid, preoccupied by Muraena ophis Linnaeus 1758 .

Echidna nebulosa : Marshall 1952: 223; Tortonese 1968: 9; Dor 1984: 26; Goren & Dor 1994: 6; Randall & Golani 1995: 851; Khalaf & Disi 1997: 39; Khalaf 2004: 35; Golani & Bogorodsky 2010: 9; Golani & Fricke 2018: 19.

Red Sea material. Red Sea: SMF 19 (1, 547, holotype of Muraena ophis ). Israel: HUJ 5239 (1, 547), Eilat; HUJ 5241 (1, 536), Eilat; HUJ 15020 (2, 410–476), Gulf of Aqaba , El Arkana . Egypt: USNM 166911 (2, 408–518), Ghardaqa (Hurghada) ; USNM 312130 (1, 601), channel at Ras Muhammad .

Comparative material. Mauritius: USNM 342096 (1, 352); USNM 345794 (1, 220). Taiwan: USNM 312122 (1, 156). Hawaii: USNM 126552 (3, 91–360). Panama: USNM 312135 (1, 267).

Description. In TL: preanal length 1.9–2.1, predorsal length 8.9–12, head length 8.1–11, body depth at anus 18–26. In head length: snout length 5.6–7.0, eye diameter 9.3–13, upper-jaw length 2.6–3.7. Pores: LL 2, SO 3, IO 4, POM 6. Vertebrae: predorsal 4–6, preanal 54–58, total 119–125.

Body moderately stout, generally deeper with growth; anus near midlength; dorsal fin begins slightly anterior to gill opening; anal fin begins immediately behind anus. Head moderate in length, snout relatively short and deep. Eye moderately small, closer to rictus than to snout tip.

Teeth stout, triangular to molariform. Intermaxillary with ca 5–6 peripheral teeth on each side, triangular to bluntly pointed, slightly retrorse, with finely serrate posterior margins in larger individuals; 0–3 median teeth bluntly pointed. Maxillary teeth uniserial, ca 6–10 on each side, bluntly pointed. Dentary teeth somewhat variable, uniserial or biserial with an outer row of small nodular teeth and an anterior inner row of 2–3 larger, stout, bluntly conical teeth; posterior to this point a single series of teeth, which in some cases appear to be a continuation of the inner series, in other cases a continuation of the outer series; in largest specimen examined, teeth become multiserial and molariform posteriorly. Vomerine teeth biserial, large and molariform, ca 6–10 on each side.

Color: light gray, white or pale brown (darker with growth), finely flecked with black, with two longitudinal rows of large, complex snowflake-like black blotches (those of ventral row are vertically elongate), containing one or more yellow spots and irregular dark edges; anterior tip of snout and lower jaw varying from white to gray; iris and anterior nostrils yellow.

Distribution and habitat. Widely distributed across the entire Indo-Pacific, from the east coast of Africa and the Red Sea to Central America. Common inhabitant of coral reefs, typically found on reef flats, sometimes in seagrass areas, usually from depth less than 3 m, but reported from the depth of 48 m; feeding largely on crustaceans, usually crabs.

Remarks. Fricke (1999) designated the specimen in the original illustration reproduced in Ahl (1789) as the lectotype and noted that Ahl published his dissertation of 1798 in 1801. Fricke (1999: 41) dated the original description of Muraena nebulosa to 1801, but that is apparently incorrect as there is a 1789 publication that differs from the 1801 reference. Smith (2012) gave the type locality as East Indies and mentioned Fricke’s designation of the lectotype as the illustrated specimen, which no longer exists. Muraena ophis Forsskål, 1775 was published in the synonymy of E. nebulosa , but without any comment or description; it is a nomen nudum, hence an unavailable name.

This species shows little morphological variation over its vast range. The three specimens from the Red Sea have slightly fewer vertebrae (119–122, N = 5) than those from elsewhere (122–125, N = 7), but the sample size is too small to draw any firm conclusions.

The three specimens from the Red Sea ( Israel), the Western Pacific ( Philippines) and the South Pacific (Society Islands) formed one joint monophyletic lineage in the phylogenetic analysis without apparent genetic divergence of the Red Sea specimen from e.g. the specimen from the Philippines (TZAIC707-06, see Fig. 48 ). A study on the genetic differentiation within E. nebulosa across the Indo-Pacific showed no marked intra-specific genetic variation in mitochondrial haplotypes ( Reece et al. 2011). One COI sequence of a specimen that was originally identified as Echidna nebulosa in Reece et al. (2010) ( HQ 122453 ) was part of a clade composed of specimens of Gymnothorax pictus (Ahl) . The reason remains unclear, and examination of the voucher specimen and/or re-sequencing of the COI gene would be required to solve the issue; however, we preliminarily re-assigned the sequence/specimen to G. pictus and suggest either a sequence mix-up or a misidentification as the cause for the unexpected placement of the sequence. Echidna nebulosa formed a well-supported clade with three other species, i.e. G. pictus , G. pseudothyrsoideus (Bleeker) and Echidna xanthospilos (Bleeker) . Other species of Echidna also formed part of well-supported clades in other parts of the phylogeny leading to a polyphyletic genus Echidna .

Figures

FIGURE 3. Echidna nebulosa. A: Dahab, Egypt; B: Dahab, Egypt. 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.