Tentaculariid trypanorhynchs (Platyhelminthes: Cestoda) from Mobula japanica (Müller & Henle) from Indonesia, with the description of two new species.

This study presents new information on tentaculariid trypanorhynchs from the Indo-Pacific region around Bali, Indonesia. Two new tentaculariid species, Nybelinia balinensis n. sp. and N. mobulicola n. sp., are described from the stomach of their myliobatid host Mobula japanica (Müller & Henle). Nybelinia balinensis n. sp. is a large-sized tentaculariid (scolex length, 6766-10,991). It can be distinguished from its congeners by a falcate metabasal armature, a unique basal armature of four rows of triangular shaped hooks, craspedote proglottids, and testes arranged in multiple layers in two separate lateral fields. N. mobulicola n. sp. can be characterized by short tentacles of 25 rows of hooks and 60 testes not reaching posterior to the ovary. A combination of a shorter basal armature of uncinate hooks without anterior extension of the base and fewer metabasal uncinate hooks with anterior extension of the base distinguishes it from N. lingualis (Cuvier, 1817). It differs from N. balinensis n. sp. in the possession of uncinate rather triangular shaped basal hooks. The Nybelinia Poche, 1926 fauna of M. japanica is highly specific, in line with a unique trypanorhynch fauna earlier described for the devil rays. This reflects their unique position as oceanic plankton feeders within the marine food web.