Xyrias

E, John, Chen, Wei-Li & Chen, Hong-Ming, 2009, Comments on the snake-eel genus Xyrias (Anguilliformes: Ophichthidae) with the description of a new species, Zootaxa 2289, pp. 61-67 : 62

Genus Xyrias Jordan and Snyder, 1901

Xyrias Jordan and Snyder 1901: 868 (type species Xyrias revulsus Jordan and Snyder 1901, by original designation and by monotypy).

Diagnosis. Ophichthid eels, subfamily Ophichthinae , tribe Ophichthini (sensu McCosker 1977), with the following combination of characteristics: jaws elongate; snout short, subconical; eye small to moderate; anterior nostril in upper lip in a short tube and laterally directed, ovate, with a minute flap; posterior nostril in upper lip and covered by a flap; dorsal-fin origin above or behind pectoral-fin tips; postorbital strut absent; two preopercular pores; teeth strong, conical, not extremely enlarged, those of vomer largest, uniserial and widely spaced; anterior intermaxillary teeth exposed before lower jaw tip, lower jaw teeth uniserial, those of upper jaw biserial or with an outer uniserial row, flanked by a large inner multiserial patch which broadens posteriorly; gill arches typically ophichthine, fifth ceratobranchial ossified, upper pharyngeal tooth plates united by a suture. A more detailed description of the gill arches, hyoid apparatus, pectoral girdle, and other osteological characters of X. revulsus is provided in McCosker (1977: 84).

Remarks. Xyrias was, until recently, known only from very few specimens of the type species. The only record of Xyrias from the East China Sea was that of X. revulsus from Diaoyu Island ( Tan (1983). McCosker (1998) reviewed the genus and included Ophichthus multiserialis Norman (1939) and Ophisurus guineensis Blache (1975) within it. He examined all of the type specimens as well as four additional specimens. To that list we add the following new records and information concerning Xyrias revulsus . Two uncatalogued specimens from the Northern Territory Museum of Australia were bottom trawled from the Arafura Sea, one (790 mm TL) from east of Evans Shoal (09o46'S, 130o14'E, 270–300 m depth), the other (603 mm TL) from north of Bathhurst Island (09o47'S, 130o25'E, 265–275 m depth). They have 19/78/157 and 20/78/158 vertebrae, respectively. Xyrias revulsus has also been observed and photographed by scuba divers, reducing their depth range to a few meters. The unmistakable snout of X. revulsus extending from a shell and gravel substrate was photographed by K. Iwai at 25 m depth off the Izu Peninsula, Japan (Anon. 1996: 1). Several individuals were seen and photographed by divers Akos and Donata Lumnitzer at depths under three meters off Kurnell, New South Wales, Australia. The Lumnitzers observed as many as three eels each dive, but only at night.

The dentition of the new species, as described below, requires an expanded diagnosis of Xyrias . Its three described congeners have a posterior patch of maxillary teeth medial to the outer row of uniserial teeth; the new species has two linear uniserial rows of maxillary teeth separated by a trough. Other than that, it appears to be very similar in physiognomy and general morphology to its congeners.