Gymnothorax phalarus , a new eastern Pacific moray eel . ( Pisces : Muraenidae )

Gymnothorax pllalarus is described from 23 individuals taken in trawl and dredge collections made on the Pacific coast of Costa Rica. The new species is nearly always syntopic with a similar species, Gymnothorax equatorialis. The new moray is distinguished by its white-spotted pattem, uniserial, slightly serrated teeth in adults, four infraorbital pores and mean vertebral formula of 6-58-140. Ofthe total of 21 valid species of morays recorded from the Pacific coast of Costa Rica, only the new species and G. equatorialis form part of the trawl fishery as the remainder are almost entirely restricted to nearshore rocky habitats. The known range of G. plla/arus is from Baja California to Pern.

The moray eel fauna of the Pacific coast of Costa Rica is abundant and diverse. To date, 19 valid species of morays have been recorded from nearshore rocky habitats and another two species by trawling in deeper waters over soft substrata. Nine of these eels, inc1uding the two deep-water species, belong to the genus Gymnothorax. In addition, Bohlke et al. (1989:149;172) referred to the presence in the eastem Pacific of oQe or two unidentified species of Gymnothorax of the subgenus Neomuraena similar to several Neomuraena in the westem Atlantic.
Trawl samples on the Pacific coast of Costa Rica routinely yield fair numbers of the white-spotted Gymnothorax (Neomuraena) equatorialis (Hildebrand) and a similar less common, undescribed species (Fig. 1). Unlike members of Neomuraena which have three infraorbital pores, the new species, described herein, possesses four infraorbital pores and slight1y serrated uniserial teeth and possibly belongs to another subgenus.
Head pores (Fig. 2) usually rimmed with darker pigment. Four conspicuous infraorbital pores; three smaller supraorbital pores; mandibular pores 5-7, usually 6 (holotype with 6-7). Jaws of equal length or lower jaw extending slightly, snout to rictus (upper jaw length) 2.1-2.9 (2.6) in HL. Teeth sharp, slender and uniserial with margins most strongly serrated on posterior edge. On upper jaw usually an anterior median fang, followed on each side by three or four widely-spaced long intermaxillary teeth, and followed by about eight maxillary teeth, the teeth evenly spaced and decreasing in size posteriorly (Fig.  3A). On lower jaw, a single row of 11-15 teeth,  the anterior three to five, similar in size and shape to intennaxillary teeth, the remainder decreasing gradually in size posteriorly, but less so than in upper jaw. Depressible replacement teeth present, in process of becoming functional. Median intermaxillary teeth absent. One or two conical vomerine teethonly on large specimens.
Vertebral,counts (Table 2)  Coloration: Color of liveand preserved specimens the same. Head and: trunk brown, becoming darker posteriorly to dusky chocolate brown or black on tall . Eye rimmed in darker pigment. Numerous small, pale, spots behind head, becoming fewer an'd larger (pupil to eye-diameter size) posteriorly; round or oval white spots very conspicuous on tail (Fig. 4A). Spots on trunk fewer and less diktinct on sorne specimens, more numerous and distínctly white on others; head and abdomen brown or straw-colored with few or no spots. Dorsal fin also white-spotted, becoming nearly black on tail; anal fin black with few or no white spots.
An immature specimen (283 mm) has small white spots commencing at snout tip; becoming larger ovals on branchial region; eye-sized white spots behind gill opening well-separated and contrasting with nearly black tail. The largest specimen, a 927 mm adult male, is dark brown, nearly black on mid dorsal line from snout to tail tip; head with a wide black ring around orbit; few well separated white specks on trunk, becoming more numerous and larger (pupil-sized) round or oval spots on tail; dorsal fin black with white spots, anal fin black without spots.
Etymology: From the Greek phalaros meaning white-spotted; to be treated as an adjective.

Distribution:
Known from Baja California, Mexico to Peru, (only Costa Rican material was utilized in the present study). Specimens of G. phalarus labeled "Gymnothorax C' or "Gymnothorax sp." were examined by the B6hlkes during their survey on the Gymnothorax ocellatus-marginatus saxicola complex, and are deposited at several institutions including SIO, LACM and USNM (E. B6hlke, pers. comm.). Taken by trawl and dredge on soft substrata between 23 and at least 295 m depth in Costa Rican waters.

REMARKS
Although not necessarily closely related, in general appearance, body shape and habitat, Gymnothorax phalarus resembles G. equatorialis. Both species are dark, white spotted eels with uniserial jaw teeth and few or no vomerine teeth. The anus is located near midbody and the tail tapers to a slender tipo Gymnothorax equatorialis is distinguished by its three infraorbital pores, different MVF values (Table 2), different jaw shape (Fig. 3B), often a median intermaxillary tooth, and by a narrower tai1 with very elongate (longer than eye diarneter), widely-spaced, terminal spots (Fig. 4B). Terminal spots on the tail of G. phalarus (Fig. 4A) are round or oval, smaller than eye diarneter, and more closely spaced.
The reef morays Gymnothorax castaneus Gilbert and G. dovií (Günther) may be related to and share several characteristics with G. phalarus. They also have four infraorbital pores, similar MVF values, uniserial teeth (but with an inner, median intermaxillary tooth) and anus near midbody. However the tail is more robust, ending in a blunt tip and the median fins are more elevated. The teeth are extremely finely serrated even on large specimens, whereas the teeth of G. phalarus are more conspicuously serrate. Both reef species are found in nearshore rocky habitats and have not been collected by trawls in deeper water.
Gymnothorax dovii is a dark brown or black eel covered with small (less than pupil size) white spots and can be. more readily confused with G. phalarus. whereas G. castaneus is brown or brownish green with few white or yellow flecks mostly on the posterior half of body and dorsal fin (McCosker & Rosenblatt 1975).
Three other spotted . eels have been reported from the mid Pacific at Easter Island (Randall & McCosker, 1975). Gymnothorax nasuta De Buen has a dark reticulum overlaying white spotting, the anterior nostril is exceptionally long (6-7% of HL), several inner median intermaxillary fangs and a row of several vomerine teeth. Gymnothorax eurostus (Abbott), in addition to a dense covering of minute white spots, presents larger (pupil diameter) black spots on the anterior third of the body; biserial maxillary teéth, three rows of intermaxillary fangs, a . .fQW of several vomerine teeth and the .. Easter Island specimens have 124-128 total vertebrae. Randall & McCosker (1975) placed Gymnothorax dentex De Buen in the synonymy of G. eurostus and described the deep-water (250 m) Gymnothorax bathyphilus. The latter species has similar dentition, but presents a light yellowish gray color with scattered dark brown blotches, mostly larger than eye and 145 total vertebrae.
No attempt is made to place G. phalarus in one oftne provisional sllogenera ofBéihlke et al.