Subfamily Ioninae Milne Edwards, 1840

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Introduction

Contained in the subfamily Ioninae are all the branchial parasites of brachyuran crabs, half the branchial parasites of thalassinidean shrimps, and one species on a palinuran lobster.

Portunicpeon tiariniae Shiino, 1937 has been recorded in Australia from Lizard Is. The species does not belong in this genus nor in similar Allokepon Markham, 1982 and probably deserves a new genus (Markham 1982). We place it here in incertae sedis. Besides the species listed, an undescribed species of Rhopalione has been identified from Australia by J. Markham.

Diagnosis

Female: All segments distinct, body only slightly distorted; frontal lamina, coxal plates and dorsolateral bosses variously developed; brood pouch completely closed, formed by 5 pairs of symmetrical oostegites; often long middorsal projections on pereon; pleon much narrower than pereon and deeply set into pereon; lateral plates present, at least first pair directed forward; pleopods biramous or occasionally uniramous; uropods uniramous and typically similar to, but larger than pleopodal exopodites; all pleonal appendages (or at least exopodites of biramous pleopods) elongate and with tuberculate to digitate margins. Male: Often about half as long as female, body frequently elongate; head separated from pereon; often midventral tubercles on some or all pereomeres and occasionally on some pleomeres; pleon of 6 pleomeres usually bearing 5 pairs of tuberculiform pleopods; uropods present or absent.

General References

Markham, J.C. 1982. Bopyrid isopods parasitic on decapod crustaceans in Hong Kong and southern China. pp. 325-391 in Morton, B.S. & Tseng, C.K. (eds). Proceedings of the First International Marine Biological Workshop: The Marine Flora and Fauna of Hong Kong and Southern China, Hong Kong, 1980. Hong Kong : Hong Kong University Press.

Milne Edwards, H. 1840. Histoire Naturelle des Crustacés, comprenant l'anatomie, la physiologie et la classification de ces animaux. Paris : Librairie Encyclopédique de Roret Vol. 3 220 acompagnée de planches.

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