Chromadoridae (Chromadorida: Nematoda) from the Indian Ocean: Difficulties in morphological identification of Actinonema Cobb, 1920 and Rhips Cobb, 1920.

Abstract

The diagnostic characteristics of ActinonemaCobb, 1920 and Rhips Cobb, 1920 are reviewed andtheir importance for genera diagnosis assessed. Threespecies of Actinonema and one species of Rhips are described. Actinonema longicaudatumSteiner, 1918 is characterised by short (2–3 µmlong) anterior sensilla, cylindrical body with arather narrow anterior end, lateral alae with inverted‘V’-patterns, wide (70–75 of cbd) double amphids andaccessory pieces composed of only the telamon which isbroad anteriorly and tapers on the posterior and along tail. Actinonema paraceltica ischaracterised by long (4–5 µm) anterior sensilla,large amphids (83–88% of cbd), lateraldifferentiation of ‘V’ pattern on each annule andaccessory pieces with telamons that have shortextensions. Actinonema smolae sp. n. ischaracterised by long and thin body, large amphidslocated close to the anterior end and six solid cones.Rhips reginae n.sp. is characterised by sixsolid cones, large (90% cbd) amphids, lateraldifferentiation of two longitudinal rows of dots anddouble jointed spicules.