Chaetonotus (Hystricochaetonotus) spinulosus Stokes, 1887

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

Chaetonotus (Hystricochaetonotus) spinulosus Stokes, 1887

Records from India. MEGHALAYA: Sharma & Sharma (1990); GENERAL RECORD: Naidu & Rao (2004), Purushothaman (2017).

Habitat (as in Indian records). Freshwater; among aquatic vegetation in ponds and tanks.

Distribution. USA, Europe and India.

Remarks. Small sized species (up to 90 μm in total length) characterized by the presence of 7-8 big, singlebarbed spines (18-25 μm in length), at mid-posterior trunk. Spines originate directly from the body surface (i.e., not from a basal scale) and are arranged in two transverse rows of 4 + 3 spines each. Some variability in these traits has been reported. For example, Schwank (1990) refers to specimens having 8 big spines originating from a basal scale. In India, a single specimen belonging to this species has been recorded so far ( Sharma & Sharma 1990). According to the authors it was only 62 μm in total length, probably the smallest adult gastrotrich ever found, and matched the original description in having 7 big spines, arranged in 4 + 3 pattern. Future studies at morphological and molecular levels should investigate the status of the different populations. We also call for a better description of the species from its terra typica (i.e., New Jersey and/or Michigan, USA).