Genus Richtersia Steiner, 1916

Emended diagnosis (based in Gharakhani et al. 2020). Body short and stout, yellow-brownish, from cylindrical to sacciform. Cuticle finely annulated with longitudinal rows of small spines. Anterior sensilla arranged in 6 + 10 pattern, all anterior sensilla setose. Amphidial fovea ventrally coiled, uni- to multispiral, or of any other derived shapes. Broad mouth opening surrounded by six soft lips and a cuticular collar. Buccal cavity nearly cylindroid, with weakly sclerotised walls. Pharynx short, cylindrical, and evenly muscular. Male reproductive system monorchic, with outstretched testis. No precloacal supplements except for modified cuticular spines. Female reproductive system didelphic-amphidelphic. Strictly marine.

Type species: Richtersia collaris Steiner, 1916

Valid species

R. argentinae Pastor de Ward & Lo Russo, 2007 R. bathyalis Soetaert & Vincx, 1987

R. beibuwanensis Fu, Cai, Boucher, Cao & Wu, 2013 R. bicornis Pastor de Ward & Lo Russo, 2007

R. bispinata Gharahkhani, Pourjam, Leduc & Pedram, 2020 R. coifsoa Fu, Cai, Boucher, Cao & Wu, 2013

R. collaris Steiner, 1916

R. coomansi Soetaert & Vincx, 1987

R. deconincki Vincx, 1981

R. demani Schuurmans Stekhoven, 1935

= R. beauforti Chitwood, 1936

R. discorda (Inglis, 1968) Gerlach & Riemann, 1973

= Richtersiella discorda Inglis, 1968

R. erinacei Gerlach, 1964

R. farcimen Gerlach, 1964

R. heipi Soetaert & Vincx, 1987

R. iberica Riemann & Schrage, 1977

R. imparis Gerlach, 1956

R. inaequalis Riemann, 1966

R. kreisi Boucher, 1975

R. mediterranea Soetaert & Vincx, 1987

R. spicana Vitiello, 1973

R. spinosa Soetaert & Vincx, 1987

R. staresensis Soetaert & Vincx, 1987