First Finding of Swallowerfish (Pseudoscopelus sagamianus, Chiasmodontidae) in the Waters of Vietnam

摘要

Swallowerfishes of the genus Pseudoscopelus Liit-ken, 1892, are represented in the World oceans by 17 species, either separated or grouped into three or four species groups, or "superspecies" (Prokofiev, 2014). One of these superspecies is P. sc/v/tfj/s-superspecies, whose species composition was finally established only recently (Prokofiev, 2014). The diagnostic traits of this superspecies are multiple rows of teeth in the middle and inner series on praemaxillare, at least three rows of teeth on dentale, usually 36 vertebrae, linear mxf that reaches praeoperculum but does not form apf and a well-developed trf with a central, spot-like extension. This superspecies includes three species: P. sagami-anus Tanaka, 1908, P. scriptus Liitken, 1892 (synonym—P. sagamianus oceanicus Prokofiev, 2011), and P. cordilluminatus Melo, 2010 (synonym— P. scriptus fide Prokofiev and Kukuev, 2007), of which only the first is known in the Pacific—in the Kuroshio Current area, in the vicinity of New Guinea, in the central Pacific, and in New Zealand waters (Prokofiev, 2009, 2011; Melo, 2010). In the South China Sea, representatives of the genus Pseudoscopelus were not known reliably, although the presence of P. sagamianus here was not ruled out, because this species was depicted (but incorrectly identified as Chiasmodon niger) in the review of fishes of Taiwan {Fishes of Taiwan, 1993; Prokofiev, 2009). This specimen is missing in the museum collections, and the exact place where it was collected remains unknown. Previously, only one swallowerfish species, Dysalotus alcocki MacGil-christ, 1905 (Randall and Lim, 2000), was reported for the South China Sea, which was known from one catch in the waters of Taiwan (Prokofiev, 2011). In addition, Chiasmodon lavenbergi Prokofiev, 2008, was found off the northeastern coast of Taiwan (Prokofiev and Kukuev, 2009; Prokofiev, 2011). Swallowerfishes have not been found so far in the South China Sea beyond the water area of Taiwan.