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

Abstract

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.

Unusual Localization of Pennella Sp. in Swordfish (Xiphias gladius) Hearts

“…Additionally, Weigert-Van Gieson histochemical staining was performed on selected sections. The parasites were macroscopically identified according to published guidelines [4,5].…”

“…The literature on Pennella spp. infestation provides little to no information about the histopathological aspect of lesions but rather focuses more on the morphological description [4]. Here, we report on 10 cases of unusual Pennella sp.…”

“…Nine officially classified species (P. balaenoptera, P. benzi, P. diodontis, P. exocoeti, P. filosa, P. hawaiensis, P. instructa, P. makaira, P. sagitta) and six species inquirendae (P. elegans, P. longicauda, P. platycephalus, P. remorae, P. robusta, P. selaris) currently belong to this genus. In addition, other 29 species of Pennella not officially recognized are indicated in the literature [4,5]. For these species, the lack of an officially recognized nomenclature is due to single reports, incomplete information, or descriptions similar to species already known but with a different name (e.g., P. rubra is synonymous with the well-known P. filosa) [6].…”

“…The host spectrum, besides morphology, can be an indicator for identifying Pennella species. They are highly specific in their host spectrum, having one or two definitive hosts per species [4]. However, P. balaenoptera can be found in various marine mammals, including whales, dolphins, porpoises, or pinnipeds [9][10][11][12].…”

The Complete Mitochondrial Genome of Pennella sp. Parasitizing Thunnus albacares

“…After metamorphosis, the female enters the host’s body surface to parasitize while the male swims freely ( Hogans et al., 1985 ). Their bodies were straight and slender, with feathery bellies and straight egg sacs ( Hogans, 2017 ). People usually judge the species of Pennella from the host, the size and number of antennal processes, the shape and arrangement of cephalothorax, etc.…”