Gastropodidae, H.K.Harring, 1913

Sharma, Bhushan Kumar, Online, Published & Version, Final, 2016, Interesting rotifers (Rotifera: Eurotatoria) from a subtropical wetland of Meghalaya, Northeast India: new records, Turkish Journal of Zoology 40 (3), pp. 433-437 : 434-436

Family: Gastropodidae

4. Gastropus minor (Rousselet, 1892)

Order: Flosculariaceae

Family: Floscularidae

5. Stephanoceros fimbriatus (Goldfusz, 1820)

Order: Collothecaceae

Family: Atrochidae

6. Cupelopagis vorax (Leidy, 1857)

Subclass: Bdelloidea

Family: Philodinidae

7. Dissotrocha aculeata (Ehrenberg, 1832)

The wetland is characterized by its subtropical, slightly acidic-circumneutral, soft, well-oxygenated, and calciumpoor waters with low free carbon dioxide and low ionic concentrations; the last salient feature warranted inclusion of the water body in the ‘Class I’ category of trophic classification according to Talling and Talling (1965). The chloride content indicated certain influence of human impact in this seepage and rainwater-fed ecosystem.

The present study revealed seven new records of rotifers belonging to six genera and six families. Of these, Colurella tesselata , Lecane stichaea , Gastropus minor , Stephanoceros fimbriatus , and Dissotrocha aculeata are new to the Indian Rotifera while Lecane dorysimilis and Cupelopagis vorax are new additions to the fauna of NEI. This report merits interest in terms of biodiversity and distribution interest and has raised the total tally of Rotifera known from Meghalaya to 141 species belonging to 41 genera and 20 families. Furthermore, the majority of these taxa, except Dissotrocha aculeata , are rare in the studied collections.

Colurella tesselata , a new record from India, is characterized by its dorsal keel and facet-like pattern of ribs on the lorica (Koste and Shiel, 1989). This species is known from African, Australian, Nearctic, Palearctic, Neotropical, and Oriental regions ( Segers, 2007). It is reported from the Oriental region from Thailand ( Sa-Ardrit et al., 2013) and Vietnam ( Trinh Dang et al., 2013); the present report extended its distribution within that region to the Indian sub-subcontinent. The lecanid L. stichaea , another new addition to the Indian Rotifera , is differentiated from its congeners L. haliclysta , L. stichoclysta , and L. verecunda by its toes bearing pseudoclaws. The examined specimens are assigned to L. stichaea following Segers (1995). This cosmopolitan species is known from the Oriental region from Thailand ( Sa-Ardrit et al., 2013) and the current report extended its distribution to the Indian subregion.

This study provided the first ‘validated record’ of Gastropus minor from India; earlier unverifiable reports of the taxon from Kashmir, Andhra Pradesh, Karnataka, Maharashtra, and Uttar Pradesh lack any validation (characters, figures, drawings, etc.) and hence they are considered dubious unless warranted. This dogma of ‘indiscriminate unverifiable reports of the rotifer taxa’ in several ‘ad hoc routine faunal lists without taxonomic expertise’ is seriously impairing the progress of knowledge of the biodiversity of the Indian Rotifera ( Sharma and Sharma, 2014a, 2014b, 2015) and needs the attention of future workers.

The sessile Stephanoceros fimbriatus is another new record from India. This rotifer is known elsewhere from the Australian, Nearctic, Neotropical, Palearctic, and Oriental regions ( Segers, 2007); it is reported from the Oriental region from Thailand ( Sa-Ardrit et al., 2013) and its distribution is now extended to the Indian subregion. The cosmopolitan bdelloid Dissotrocha aculeata is rather common in various samples, though invariably contracted, but identifiable. This species is known from the Oriental region from Thailand ( Sa-Ardrit et al., 2013) and the present record has extended its distribution to the Indian subcontinent.

Trinh Dang et al. (2015) recently described L. dorysimilis sp. nov. from the hygropsammon of Bau Thiem Lake, Thua Thien Hue Province of Vietnam, and considered it to be a psammophilous or even psammoxene littoral taxon rather than a psammobiontic species.