Pennella diodontis Oken, 1816

Hogans, W. E., 2017, 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, Zootaxa 4244 (1), pp. 1-38 : 16-17

Pennella diodontis Oken, 1816

( Fig. 7 )

Synonyms. Pennella cervicornis Heegaard, 1943 , P. plumosa ( Dekay, 1844) Type host and locality. Diodon sexmaculatus , Philippines.

Morphology. Size: 24–28 mm. Papillae: partial coverage, clavate and club-like, consistent in size and shape, not found in organized groups. Holdfasts: two only, short. First antenna with three segments, second with two segments. Plumes: simple, single.

Remarks. A valid species. Original description from porcupine fish, Diodon sexmaculatus (= D. holacanthus ) ( Oken 1816); redescription from the same host species, Ceylon ( Kirtisinghe 1932; Fig. 7 ). Considered incorrectly as infesting two host genera: Lophius and Diodon ( Wilson 1917) . The history of P. diodontis was often confused with that of P. sagitta ( Wilson 1917) , however, P. diodontis reported from Lophius was an error of Blainville (1822) based on a poor description and incorrect host identification; P. diodontis is in fact a parasite of porcupine fish ( Diodontidae : Diodon ) and P. sagitta is found so far only on frogfish (Antennaridae: Histrio , possibly Antennarius ) ). Lasarus and Sreenivasan (1977) reported P. diodontis from the moorish idol (Zanculus canascens (= Z. cornuta) in the Indian Ocean. The single habitus figure and brief description are not sufficient to confidently place their specimens (eight) in P. diodontis . However, the size of the parasite (26mm) and the cephalothoracic papillae (few small at center, and larger branched papillae around the cephalothorax periphery) are reminiscent of the species. As a parasite of Diodon , P. diodontis is a small species with uniformity in most structures between specimens ( Hogans 1988a), however, its cephalothoracic papillae may vary slightly in arrangement and number depending on the individual parasite ( Hogans 1988a; Heegard 1943).

Figures

FIGURE 7. Pennella diodontis, a. entire parasite; b. cephalothorax, dorsal; c. same, ventral; d. first and second antenna, dorsal; e. second and third swimming legs (redrawn from Kirtisinghe, 1935). Scale bars: a = 2.0 mm; b, c = 0.2 mm; d, e = 0.02 mm.