Onychopontia, Sak & Huys & Karaytuğ, 2008

Sak, Serdar, Huys, Rony & Karaytuğ, Süphan, 2008, 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), Zoological Journal of the Linnean Society 152, pp. 409-458 : 448

GENUS ONYCHOPONTIA GEN. NOV.

The close relationship between A. orientalis ( Krishnaswamy, 1957) , A. intermedia Rouch, 1962 , and A. peteraxi Mielke, 1982a was first recognized by Mielke (1982a), who regarded the sexual dimorphism on the P3 endopod as a synapomorphy linking these species. The transformation of this ramus is more derived than the condition displayed in Psammoleptastacus , where the two-segmented state is retained in the male. Species of the latter genus have a welldeveloped P1 exopod and an inner serrate seta on P2 enp-2. In A. orientalis , A. intermedia , and A. peteraxi , the P1 exopod is more condensed and the serrate seta on P2 enp-2 is lost. These three species are here collectively transferred to a new genus, Onychopontia , together with a new species from Australia found among the type material of N. spinicaudatus . Additional autapomorphies for Onychopontia are the modification of the two outer elements on P1 exp-3 into naked setae and the strong reduction of the outer geniculate seta; in all other genera the outer elements are spiniform and pinnate, and the outer geniculate seta is well developed. Lang’s (1965) claim that P. orientalis belongs to Arenocaris is obviously a slip of the pen, which was inadvertently adopted by Bodin (1967). The current known distribution of the genus is highly disjunct, with species recorded from Brazil, India, Australia, Galápagos, Panamá, Chile, and Venezuela.

Diagnosis: Arenopontiidae . Urosomites: without conspicuous surface ornamentation. Anal somite: without paired dorsolateral spinous processes. Anal operculum: not modified. Hyaline frills of abdominal somites with narrow rectangular lappets. Caudal ramus: without dorsolateral spur near medial margin. P1 exopod: three-segmented, short; exp-1 longest, with outer spine; exp-3 with two spines and two geniculate setae. P1 endopod: not prehensile, longer than exopod; enp-2 with two geniculate setae. P2–P3 endopods: two-segmented; inner serrate seta of P2 enp-2 absent. P3 endopod: without outer distal element (but see variability in Onychopontia peteraxi ). P4 endopod: with outer distal element well developed or reduced. Armature formula as follows:

Exopod Endopod

P2 0.0.021 0.020 [or 0.010*] P3 0.0.021 0.010 [or 0.020*†] P4 0.0.021 0.020

P3 endopod male: sexually dimorphic, onesegmented, with distal curved spine. P5: with outer basal seta and either three or four discrete elements in female; with outer basal seta and three elements in male, innermost one distinctly smaller than in female, and sometimes fused at base. P 6 male: with two setae.

Type species: Onychopontia nichollsi sp. nov.

Other species: Psammoleptastacus orientalis Krishnaswamy, 1957 = Onychopontia orientalis ( Krishnaswamy, 1957) comb. nov.; A. intermedia Rouch, 1962 = Onychopontia intermedia ( Rouch, 1962) comb. nov.; A. peteraxi Mielke, 1982 = Onychopontia peteraxi (Mielke, 1982) comb. nov.

Etymology: The generic name is derived from the Greek onyx (ONUx; genitive onychos), meaning nail, or claw, and the suffix pontia (PONTIA, the sea), commonly used in the formation of interstitial copepod names, and refers to the morphology of the modified P3 endopod in the male.