Acyclus

Meksuwan, Phuripong, Pholpunthin, Pornsilp & Segers, Hendrik, 2011, Diversity of sessile rotifers (Gnesiotrocha, Monogononta, Rotifera) in Thale Noi Lake, Thailand, Zootaxa 2997, pp. 1-18 : 5

Acyclus sp.

( Figs 2a–2 c)

Although only a single specimen of this taxon was observed, we believe that it may represent an undescribed species. Morphologically, the animal is characterized by a prominent bifid anterior margin of dorsal corona lobe ( Fig. 2 c) which is reminiscent of Atrochus tentaculatus Wierzejski, 1893 , the sister taxon of Acyclus . The single known species of Acyclus , A. inquietus Leidy, also occurs in Thale Noi Lake but is easily distinguished by a rounded anterior margin of dorsal corona lobe. Moreover, the specimen of Acyclus sp. was observed predating on a colony of Lacinularia flosculosa (Müller) , whereas all of the specimens of Acyclus inquietus we observed were found in association with colonies of Sinantherina socialis (Linnaeus) . Acyclus inquietus feeds on eggs and larvae of S. socialis whereas Acyclus sp. was seen to predate on adult specimens of L. flosculosa ; the Acyclus sp. takes up a Lacinularia in its vestibulum, sucks out its content of its victim and finally releases the remains, an empty trunk and foot.

Figures

FIGURES 2 A – 2 I. Acyclus sp.; Collotheca spp. 2 a – 2 c: Acyclus sp.; 2 d – 2 f: Collotheca algicola (Hudson, 1886); 2 g – 2 i: Collotheca ambigua (Hudson, 1883). Scale bars: 2 a – 2 c, 2 d, 2 g = 100 µm; 2 e – 2 f, 2 h – 2 i = 50 µm.