Chaetonotus (Hystricochaetonotus) novenarius Greuter, 1917

Chatterjee, Tapas & Todaro, M. Antonio, 2021, An annotated checklist of the chaetonotidan Gastrotricha from India, Zootaxa 5027 (3), pp. 332-350 : 336-337

Chaetonotus (Hystricochaetonotus) novenarius Greuter, 1917

Records from India. MAHARASTRA: Nagpur – Visvesvara (1964); GENERAL RECORD: Naidu & Rao (2004), Purushothaman (2017).

Habitat (as in Indian records). Freshwater; in ponds and tanks, sometimes in moss.

Distribution. Europe and India.

Remarks. This species was originally described from Switzerland by Greuter (1917); since then, it has been found twice, by Visvesvara (1964) in India and by Balsamo (1982, 1983) in Italy. A key character of the species is the presence of 9 ‘giant’ single barbed spines (64-84 μm in length) originating at mid-posterior trunk and arranged in three rows and three columns. Morphology of the Indian specimens agree well with the original description, except for the size; in fact, the Indian specimens appear much smaller compared to the Swiss animals (111-115 μm vs 193 μm in total length). Size of the Indian specimens approaches that of the Italian gastrotrichs, which have a total length of 106-138 μm. On the other hand, the ‘giant’ spines of the Italian specimens are double barbed. Future investiga- tions, at morphological and molecular levels, should clarify if the differences accounted fall within the intraspecific variability of the C. novenarius taxon or are instead clues of populations distinctness i.e., specimens from the three countries belong to three distinct species.