Faunal change over 3 decades to reveal Rotundocollarette capoori n.gen., n.sp., a unique anisakid from Johnius dussumieri from the Central west coast of India at Goa

A unique anisakid roundworm, Rotundocollarette capoori n. gen., n.sp. infesting Johnius dussumieri from the Central West coast of India at Goa has been described. The worms are typically characterized by a cephalic collarette, a muscular collarette in post-caudal zone, intestinal caecum and a ventricular appendix. 3 pores, a part of cephalic infrastructure–a dorsal oral aperture, a dorso-laterally placed genital pore, and a sub-ventral excretory pore, at the junction of the bases of the 2 ventro-lateral lips, were typically unique as revealed by SEM studies. A pair of large squarish teeth flanked each of these three pores in the cephalic region, with 3–5 denticles in the median group, at the junction of the two arms of V-shaped structure, that joined 26–29 denticles on each arm of this V-shaped formation, running parallel and crossed past dentigerous ridges on each lip. In addition, a set of 49–50 medially organized denticles occupying the dorsal arm of V-shaped formation, in the medial space, were a conspicuous configuration, besides 70 min triangular denticles at the junction of sub-ventral lips. A spined mucron at the tip of tail. The key provided by Moravec and Justine (Parasite 27:58, 2020. https://doi.org/10.1051/parasite/2020053 ) to segregate Porrocaecum -like nematode genera ( Porrocaecum, Pseudoterranova, Pulchrascaris, Euterranova, and Neoterranova ) has been revised to include the newly proposed genus, Rotundocollarette capoori n.gen., n.sp. The significance of the emerging nematode as an environmental bioindicator has been specified.