Expanded description of Neoechinorhynchus (Hebesoma) manubrianus (Acanthocephala: Neoechinorhynchidae) from marine fish in Halong Bay, Vietnam

Neoechinorhynchus manubrianus Amin, Ha & Ha, 2011 (Acanthocephala: Neoechinorhynchidae) (formerly Neoechinorhynchus manubriensis Amin, Ha & Ha, 2011), was recently described based on optical microscopy of four males and two females (none was gravid) from caroun croaker, Johnius carouna (Cuvier), flower croaker, Nibea albiflora (Richardson), and silver croaker, Pennabia argentata (Houttuyen) (Sciaenidae) in Halong Bay, Vietnam. Subsequently, many more specimens became available from N. albiflora that were studied using SEM. SEM studies showed many additional features that were not possible to discern with optical microscopy. These included the prominent angulation of the anterior trunk, the presence of (1) anterio-dorsal and (2) undulating mid-lateral fin-like protrusions of the body wall, uniquely shaped eggs as well as details of trunk micropores, proboscis, bursa, and female gonopore. Microscopical examination of eggs from the new collection demonstrated the presence of polar prolongation of fertilization membrane which places N. manubriensis in the subgenus Hebesoma. The features of trunk angulation, trunk fins, and egg morphology further distinguish N. manubriensis from all other species of Neoechinorhynchus Stiles and Hassall, 1905 from Vietnam or from any where else in the world.