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Anarchias cantonensis (Schultz, 1943)
Family Muraenidae
Original Published Description: Schultz, L.P. 1943. Fishes of the Phoenix and Samoan Islands collected in 1939 during the expedition of the U.S.S. “Bushnell.” Bulletin of the United States National Museum 180:1-316. View Article Here: http://si-pddr.si.edu/dspace/handle/10088/10193
Overview General Description Small, brown moray eel with light mottling. Distinguished from other morays by restriction of anal and dorsal fins to posterior tip of the tail (subfamily Uropterygiinae). Among subfamily Uropterygiinae, members of the genus Anarchias are unique in having an extra head pore medial and adjacent to the posterior nostril (see schematic here). There are two recently described species (Anarchias schultzi and Anarchias exulatus; Reece et al. 2010) that closely resemble Anarchias cantonensis and can be difficult to differentiate among. Anarchias cantonensis is distinguished from A. exulatus and A. schultzi by the position of the fourth supraorbital pore, anteromedial to the posterior nostril and separated from it by an interval of normal, pigmented skin (see schematic). It has fewer vertebrae (98-108) than A. exulatus and A. schultzi (110-117 and 105-113 respectively) and a longer snout-anus distance (45.1-50.6%TL vs. 40.3-45.1% and 41.5-45.4%). It also differs in color pattern from A. exulatus and A. schultzi by having discrete, sharply defined pale spots, as opposed to larger, more diffuse pale areas oriented vertically in A. exulatus and the uniform brown of A. schultzi.
Detailed Description Meristic and morphometric characters in table form here. Body moderately elongate, anus at or slightly before midlength. Gill opening low on side of body. Head and snout relatively blunt, tip of snout broadly rounded; eye moderate in size, about midway between tip of snout and rictus. Anterior nostril tubular, near tip of snout, projecting anterolaterally; posterior nostril with low rim, on top of head above middle of eye. Lateral line reduced to two pores at anterior end of canal above and before gill opening. Supraorbital canal with four pores: one at tip of snout below and slightly ahead of anterior nostril (the ethmoidal pore), one directly medial to anterior nostril, one on top of snout slightly behind level of anterior nostril, and one adjacent to and slightly anteromedial to posterior nostril, separated from nostril by narrow section of pigmented skin. Infraorbital canal with four pores along upper jaw: one below and slightly behind anterior nostril, one between anterior nostril and eye, one below middle of eye, and one slightly behind posterior margin of eye; no pores behind eye. Preoperculomandibular canal with six pores, first at tip of lower jaw, last directly below rictus; no pores in preopercular section of canal. Maxillary teeth biserial, those of outer series small, fixed, conical, recurved, and closely spaced, continuous around front of jaw with outer row of intermaxillary teeth, similar in size and shape; inner row maxillary teeth fewer, larger, and more widely spaced, conical, straight, depressible, extending posteriorly to approximate end of outer series, and continuous anteriorly with intermediate row of intermaxillary teeth, similar in size and shape. Two to three median conical, straight and depressible intermaxillary teeth, increasing in size posteriorly. Vomerine teeth small, conical, uniserial, in line with but well separated from median intermaxillary teeth. Mandibular teeth biserial, outer teeth small, fixed, recurved, continuous around front of jaw; inner teeth larger, straight, depressible, more widely spaced, continuous around front of jaw (see here). Adults with pale, irregular stellate spots on brown background, spots usually well defined, about same size, not forming indistinct bars. Juveniles with small, round pale spots on brown background, becoming more irregular with growth (see here). A small species, the largest specimen examined 219 mm TL.
Similar Speciess As described in the species description, Anarchias cantonensis can be difficult to distinguish from its two sister species, A. schultzi and A. exulatus. If you are having trouble, use this dichotomous key, and view pictures of the species side by side here.
Ecology and Distribution Distribution Tropical Indo-West Pacific from the central Indian Ocean in the west to Phoenix and Line Islands in the east. The southernmost records are from about 21 degrees South in Tonga, the northernmost from about 19 degrees North in the Philippines. It occurs in the eastern Indian Ocean but has not been recorded anywhere west of the Maldives. Although it reaches as far as Palmyra Island in the east, it does not occur in the Hawaiian Islands or anywhere in French Polynesia. Ecology Most specimens have been collected in relatively shallow water on coral reefs and rocky areas along the shore. We have no records deeper than 10 meters. They are cryptic in habit and are rarely if ever seen except when collected using ichthyocides. Phylogenetic Relationships The evolutionary relationships of this genus are broadly described by sequences of the entire mitochondrial genome by Inoue et al. (2010), although their analyses did not include this species. Genetic data for the genus are available at GenBank here. Monophyly of the subfamily that contains the genus has been demonstrated in Reece et al. (2010) and Loh et al. (2008). Their closest relatives are two species that were until recently synonymized; Anarchias schultzi and Anarchias exulatus.
Taxonomy Uropterygius cantonensis Schultz, 1943:27 [Type locality: Phoenix Islands, Canton Island] Anarchias cantonensis. Schultz, 1953:146. Broader taxonomy: Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Actinopterygii; Neopterygii; Teleostei; Anguilliformes; Muraenidae; Anarchias
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