Habrotrocha pusilla ( Bryce, 1893 )

Lee, Sue Yeon, Yoo, Jung Sun & Kim, Seung Tae, 2017, New records of 13 rotifers including Bryceella perpusilla Wilts et al., 2010 and Philodina lepta Wulfert, 1951 from Korea, Journal of Species Research 6, pp. 26-37 : 31

6. Habrotrocha pusilla ( Bryce, 1893)

Callidina pusilla Bryce, 1893, p. 201 , fig. 2.

Habrotrocha pusilla : Donner, 1970, p. 517, Abb. 2g, Abb. 3f.

Material examined. One specimen found in wet leaf litter from Daegwallyeong, Pyeongchang-gun, Gangwon-do, 37°41 ʹ 19.7 ʺ N 128°45 ʹ 39.0 ʺ E, 5 June 2016.

Diagnosis. Corona slightly narrower than cingulum. Pedicel very short. Sulcus very narrow. Upper lip slightly arched and rimmed. Cingulum somewhat expanded laterally. Cingulum pad angular medially. Lateral margin of antenna pseudosegment swollen. Teeth 6/6. Spurs short and conical. Egg oval.

Measurements. Total body length in feeding 214 μm. Antenna pseudosegment width 27 μm. Corona width 25 μm. Cingulum width 26 μm. Cingulum pad width 29 μm.

Remarks. Habrotrocha pusilla lives in a net made of mucus and debris. Habrotrocha pusilla differs from H. pusilla textrix in the following characteristics: (1) the rim of upper lip is wider in H. pusilla textrix , (2) each anterolateral corner of cingulum is somewhat expanded in H. pusilla , (3) the cingulum pad of H. pusilla is angular medially, while that of H. pusilla textrix is round medially, and (4) the lateral margin of antenna pseudosegment is swollen and round in H. pusilla .

The dental formula of the Korean specimen is 6/6 while that of the type specimen was 4/3. Habrotrocha pusilla is probably cosmopolitan because it has been reported from Central Africa, Europe, New Zealand, North America, Pacific islands ( Donner, 1965), Brazil ( Koste, 2000), and South Africa ( Koste, 1996).

Kaya (2013) reported this species from Erzurum (eastern part of Turkey), which was the first Asian record of it.

World distribution. Probably cosmopolitan.

Deposition. In a permanent slide, deposited in the collection of the National Institute of Biological Resources, Incheon, Korea ( ZIIYIV0000004841 ) .