Review of Pennella Oken, 1816 (Copepoda: Pennellidae) with a description of Pennella benzi sp. nov., a parasite of Escolar, Lepidocybium flavobrunneum (Pisces) in the northwest Atlantic Ocean.

The genus Pennella Oken, 1816, mesoparasitic copepods from marine fish and mammals, is reviewed with the objective of determining the validity of members of the genus. Details of the external morphological structures of the adult female are presented. Pennella species are differentiated based on a combination of characters: the type of host parasitized, overall length of the parasite, shape, size and configuration of cephalothoracic papillae, segmentation of the first and second antenna, holdfast horn number, shape and configuration, and structure of the abdominal plumes. A new species of Pennella, Pennella benzi sp. nov., is described from the escolar, Lepidocybium flavobrunneum in the northwest Atlantic. Pennella balaenoptera Koren & Danielssen, 1877 is reported from the harbor porpoise (Phocaena phocaena) in the Bay of Fundy, a new locality record. The validity of 44 species is assessed; nine species (P. balaenoptera Koren & Danielssen, 1877, P. benzi sp. nov., P. diodontis Oken, 1816, P. exocoeti (Holten, 1802), P. filosa Linnaeus, 1758, P. hawaiiensis Kazachenko & Kurochkin, 1974, P. instructa Wilson, 1917, P. makaira Hogans, 1988 and P. sagitta Linnaeus, 1758) are considered substantiated and valid; six species (P. elegans Gnanamuthu, 1957, P. longicauda Gnanamuthu, 1957, P. platycephalus Gnanamuthu, 1957, P. remorae Murray, 1856, P. robusta Gnanamuthu, 1957, and P. selaris Kirtisinghe, 1964) exhibit unique characteristics, but are based on descriptions of single specimens, have not been found since the original reports and are considered as species inquirendae; the remaining species are unsubstantiated and invalid based on inadequate or missing original descriptions, or are designated as synonyms of valid species. A key to the valid species of the genus is provided.

Case report: concurrent herpesviral and presumptive iridoviral infection associated with disease in cultured shortnose sturgeon, Acipenser brevirostrum (L.), from the Atlantic coast of Canada.

Approximately 8 weeks after a chlorine insult associated with the city water supply, shortnose sturgeon, Acipenser brevirostrum (L.), from one group presented with small (3-4 mm) irregular foci of cutaneous pallor that involved the dorsocranial integument with progressive ulceration of the nascent lesions. Various bacterial organisms were isolated from the cutaneous lesions, but not from the internal viscera. Histologically, the nuclei of the intralesional and perilesional epidermal cells often exhibited margination of the chromatin that resulted in a homogenous, pale, amphophilic, tinctorial quality of the nucleoplasm consistent with a herpesvirus infection. In addition, rare lamellar epithelial cells were prominently enlarged due to an abundant, dense, basophilic cytoplasm characteristic of an iridovirus infection. Inoculation of cutaneous lesion and kidney, spleen, liver sample pools from affected shortnose sturgeon onto white sturgeon spleen (WSS-2) cell line induced cytopathic effect characterized by syncytia formation. Ultrastructural analysis of infected WSS-2 cells revealed viral particles with a characteristic herpesvirus morphology. Intranuclear hexagonal capsids had a diameter of 95-108 nm, and enveloped particles present in the cytoplasm of infected cells had a diameter of 176-196 nm. This is the first report of a herpesvirus and a possible iridovirus-like infection in shortnose sturgeon.