A new species of Parapleurocryptella Bourdon, 1972 (Isopoda: Bopyridae) from deep water squat lobster hosts of New Zealand with description of larval stages and transfer of the genus to Pleurocryptellinae

Squat lobsters (Decapoda: Anomura) harbor a high diversity of symbionts, including many parasitic isopod species (Epicaridea: Bopyridae) that reside in their branchial chambers. We describe the bopyrid Parapleurocryptella poha n. sp., found infesting at least four species of squat lobsters from New Zealand. The new species displays morphological traits characteristic of the genus Parapleurocryptella Bourdon, 1972 but it is distinct from the two other described species, P. minuta Bourdon, 1972 and P. elasmonoti Bourdon, 1972, based on the form of the female head as well as male antennal segmentation, midventral tubercles, and dactyl size. Additionally, the new species is widely separated geographically and occurs on different host species compared to others in the genus. The morphology of mature male and female specimens is described, and we show a significant positive correlation of mature female parasite length with host size. The first description of the epicaridium larva of any species of Parapleurocryptella is provided and illustrated using SEM. Epicaridium larvae of the new species possess posterior external yolk sacs, a feature previously reported for larvae in only two other bopyrid genera: Pleurocryptella Bonnier, 1900 and Paragigantione Barnard, 1920. A discussion of the potential impacts of this structure to our understanding of bopyrid life cycles is provided. Additionally, the genera Pleurocryptina Nierstrasz & Brender à Brandis, 1929 and Pagurocryptella Boyko & Williams, 2010 are transferred to Pleurocryptellinae from Pseudioninae and Pseudione kossmanni is transferred to Pleurocryptella as Pleurocryptella kossmanni (Nierstrasz and Brender à Brendis, 1923) nov. comb. based on examination of the holotype.