Tuesday 3 July 2012

New species of Priapiumfish from the Mekong Delta.

Priapiumfish (Phallostethidae) are small partially translucent fish from Southeast Asia. The male Priapiumfish bear a unique organ, the priapium, under the throat, which is used in mating, clasping the females and fertilizing them internally; internal fertilization is unusual in Bony Fish, though common in Sharks, which also have clasping organs.

In a paper published in the journal Zootaxa on 3 July 2012, Koichi Shibukawa of the Nagao Natural Environment Foundation and Dinh Dac Tran and Loi Xuan Tran of the College of Aquaculture and Fisheries at Can Tho University describe a new species of Priapiumfish from the Mekong Delta in Vietnam.

The new species is placed in the existing genus Phallostethus, and given the specific name cuulong, from the Vietnamese name from the Mekong Delta. Phallostethus cuulong is a roughly 25 mm translucent white fish found swimming at depths of 0.5-3.5 m in tidal canals on the Mekong Delta.

Phallostethus cuulong. (A) Male. (B) Female. Shibukawa et al. (2012).

Head and anterior part of body of Phallostethus cuulong, Specimens are temporally stained with cyanine blue. (A) Lateral view of left side of head and body of male. (B) Lateral view of right side of head and body of male. (C) Lateral view of left side of head and body of female. (D) Ventral view of head and body of female. Shibukawa et al. (2012).

Lateral view of head and anterior part of body of cleared and stained specimen of Phallostethus cuulong. Shibukawa et al. (2012).

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