Saturday 28 January 2017

Rhagovelia caudata & Rhagovelia bisinuata: Two new species of Riffle Bug from Vietnam.

Riffle Bugs, Veliidae, are small, aquatic, carnivorous Hemipteran Insects related to Water Striders. members of the genus Rhagovelia are found around the world, though they are at their most diverse in the Indo-Australian region, with 30 species known on each of the Philippines, Borneo, Sulawesi, and New Guinea. However a much lower diversity has been recorded on the nearby Southeast Asian mainland, with eight species recorded in Thailand, five in Peninsula Malaysia, four in Vietnam, two in Laos and none in Cambodia, though this may be due to limited recording in these areas rather than a lower diversity.

In a paper published in the Raffles Bulletin of Zoology on 27 December 2016, Nguyễn Xuân Quýnh and Trần Anh Đức of the Department of Invertebrate Zoology at the Hanoi University of Science describe two new species of Rhagovelia from Vietnam.

The first new species is named Rhagovelia caudata, where 'caudata' refers to orange markings found on the abdomens of both sexes. The species was found in Nghe An, Dien Bien, Lai Chau, Ha Giang, Phu Tho, and Thanh Hoa provinces. These Bugs are small, with males reaching 2.47–2.75 mm and females reaching 2.66–3.00 mm. They are black in colour, with orange-brown and yellow markings.

Rhagovelia caudata, (1) male, (2) female. Nguyễn & Trần (2016).

The second new species is named Rhagovelia bisinuata, where 'bisinuata' refers  to the parameres of the males (part of the reproductive apparatus) which are sinuate (wavy) in form. The species was found in Nghe An, Lao Cai, Ha Giang, Vinh Phuc, Phu Tho, and Ha Tinh provinces. Males of this species reach 3.00–3.35 mm in legth and females 3.05–3.50 mm. The Bugs are black in colour, with yellow and brown markings.

Rhagovelia bisinuata, (3) male, (4) female. Nguyễn & Trần (2016).

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