Chaetonotus (Captochaetus) gastrocyaneus Brunson, 1950

Chatterjee, Tapas & Todaro, M. Antonio, 2021, An annotated checklist of the chaetonotidan Gastrotricha from India, Zootaxa 5027 (3), pp. 332-350 : 333-334

Chaetonotus (Captochaetus) gastrocyaneus Brunson, 1950

Records from India. ASSAM: Ghorajan, Hiragota, Akhepeti, Bamoni— Sharma & Sharma (2008) ; ODISHA: Cuttack— Sharma (1987); GENERAL RECORD: Naidu & Rao (2004).

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

Distribution. Published records of this species are from the USA and India.

Remarks. The species derives its name from the cyan colour of the gut, very likely due to the cyanobacteria on which it feeds on. The bluish colouration was reported in the original description of the species by Brunson (1950), and has been recently observed in specimens from the US collected by Dr. Bas Kooijmanone (see picture at http://www.gastrotricha.unimore.it/picturegallery.htm). One of us (MAT) has seen gastrotrichs with a bluish gut content during his expedition in South Africa (e.g., Todaro et al. 2013); size and general appearance of the South African specimens are very similar to the American species (MAT, unpublished). Gastrotrich specimens identified as C. gastrocyaneus have been found twice in India, respectively by Sharma (1987) and Sharma & Sharma (2008). Surprisingly neither Sharma & Sharma (1990) nor Purushothaman (2017) did mention this species name in their lists of freshwater Gastrotricha from India.

Morphometric data provided for the Indian specimens are very scanty and the authors never mentioned these gastrotrichs to have a cyan-coloured intestine, which is a trademark trait for the species. Because of the poor morphological data and in the absence of any reference to the colour of their gut, we consider the identification performed so far of these Indian specimens to be unreliable; consequently, C. gastrocyaneus should not be considered part of the Indian fauna.