Disentangling the subgeneric division of Arenopontia Kunz, 1937: resurrection of Psammoleptastacus Pennak, 1942, re-examination of Neoleptastacus spinicaudatus Nicholls, 1945, and proposal of two new genera and a new generic classification (Copepoda, Harpacticoida, Arenopontiidae)

Abstract

A new generic classification is proposed for the 32 valid species of the interstitial marine family Arenopontiidae (Copepoda, Harpacticoida), primarily based on new observations of type species and reliable descriptions from the literature. The subgeneric division of Arenopontia Kunz, 1937 is abolished, and both Arenopontia and Neoleptastacus Nicholls, 1945 are upgraded to full generic rank. Arenopontia is restricted to the subterranea group, comprising Arenopontia subterranea Kunz, 1937 (type), Arenopontia problematica Masry, 1970, Arenopontia nesaie Cottarelli, 1975, and Arenopontia riedli Lindgren, 1976. The doubtful status of both Arenopontia pontica Apostolov, 1969 and recent Egyptian records of A. nesaie is discussed, and the alleged cosmopolitanism of A. subterranea is reviewed. Arenopontia is characterized by the unique morphology of the P1 (prehensile endopod, armature of distal segments of exopod and endopod). The genus Psammoleptastacus Pennak, 1942 is reinstated to accommodate Psammoleptastacus arenaridus Pennak, 1942 (type), Arenopontia stygia Noodt, 1955 and Psammoleptastacus barani sp. nov. The latter is described from the Turkish Black Sea coast, and had previously been identified as A. stygia in Bulgarian waters. The species identified as A. subterranea by Rao & Ganapati in 1969 is considered species inquirenda in Psammoleptastacus. Neoleptastacus is resurrected to accommodate all arenopontiids that have an inner spinous process on the P5. The Chilean species Arenopontia clasingi Mielke, 1985, Arenopontia pacifica Mielke, 1985, and Arenopontia spicata Mielke, 1985 are transferred to Neoleptastacus. The genus Pararenopontia Bodiou & Colomines, 1986 is considered a junior synonym of Neoleptastacus, with its type species Pararenopontia breviarticulata (Mielke, 1975) being relegated to species incertae sedis in this genus. The monotypic genus Mesopontia gen. nov. is established to accommodate Arenopontia dillonbeachia Lang, 1965, which holds an intermediate position between Arenopontia and Neoleptastacus. Material from Puget Sound identified as Arenopontia spinicaudata (Nicholls, 1945) by Chappuis in 1958 is attributed to Mesopontia dillonbeachia comb. nov.Psammoleptastacus orientalis Krishnaswamy, 1957, Arenopontia intermedia Rouch, 1964, and Arenopontia peteraxi Mielke, 1982 are transferred to a new genus, Onychopontia gen. nov., together with Onychopontia nichollsi sp. nov. (type), which was discovered among type material of Neoleptastacus spinicaudatus Nicholls, 1945. Redescriptions are given for A. nesaie, P. arenaridus, N. spinicaudatus, and M. dillonbeachia. A key to the five arenopontiid genera as well as keys (or comparative tables) to the species of Arenopontia, Onychopontia, Mesopontia, and the spinicaudatus lineage of Neoleptastacus are provided.