Homoeoscelis meridionalis sp. nov. (Copepoda, Nicothoidae) parasitic on two cumaceans from southern South America with comments on its biology, and partial redescription of H. frigida Hansen, 1923

Abstract

The adult female and male, and the copepodite stage of the nicothoid copepod Homoeoscelis meridionalis sp. nov. are described. This parasite infests the branchial chambers of two closely related cumaceans from southern South America: Diastylis planifrons and D. fabrizioi. The maxilliped of the adult female of Homoeoscelis minuta is reillustrated, and the copepodite stage of H. frigida is briefly redescribed on the basis of their respective type materials. Of the 1768 specimens of Diastylis fabrizioi examined, 2.6% were found to be infested by Homoeoscelis meridionalis sp. nov. The copepod prevalence differs significantly between the female and male of D. fabrizioi (4.2 vs. 0.7%), and it was much higher in older instars of D. fabrizioi (adults and subadults) than in younger ones (juveniles and mancas) (7.1 vs. 0.3%).

Keywords:

• Copepoda
• Cumacea
• Homoeoscelis meridionalis sp. nov.
• H. frigida
• H. minuta
• parasitic
• South-West Atlantic

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

The authors are grateful to Mr Fabrizio Scarabino for providing most of the specimens studied in this paper. Special thanks are given to Dr Jørgen Olesen for the loan of the syntypes of Homoeoscelis minuta, H. frigida and H. longipes, and for translating from Danish into English the handwritten labels that accompany this type material. We also thank Dr Martín Torres Jordá for the statistical analysis, Dr Peter Rehm and Dr Christopher Boyko for their help with the literature, and Mr Fabián Tricárico for the scanning electron micrographs. Dr Geoffrey Boxshall provided very helpful remarks on an earlier version of this manuscript. This research was partially supported by the Agencia Nacional de Promoción Científica y Tecnológica (PICT 02-11180), the University of Buenos Aires (Grant X162), and the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Argentina).

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark