PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 117(1 ):76-87. 2004. Description of a new Synidotea species (Crustacea: Isopoda: Valvifera: Idoteidae) from Hawaii Wendy Moore University of Arizona, Department of Entomology, Tucson, Arizona 85721-0036 U.S.A., email,
[email protected] Abstract. — This paper provides the first description of a Hawaiian isopod of the genus Synidotea, S. oahu n. sp. This species is most similar to S. laevi-dorsalis (Miers, 1881) and S. harfordi Benedict, 1897. A list of Synidotea species described to date with biogeographic information, and a list of all marine isopods described from the Hawaiian Islands, are provided. This paper provides the first description of a Synidotea species from the Hawaiian Islands. The isopod genus Synidotea Har-ger, 1878 currently contains 57 species, in-cluding the species herein described (see Table 1). The following characters define this genus: penes fused forming penial plate, fifth oostegites absent, and sexually dimorphic mouthparts (Poore 2001). In ad-dition, Synidotea species possess the fol-lowing combination of characters: antennae 2 flagellum multiarticulate, maxillipedal palp triarticulate, pleon with one partial su-ture, pereonites 2-4 coxal plates not visible in dorsal aspect and (unlike most other val-viferan genera) pereonites 5-7 tergite-coxal plate sutures can be either present or absent. The Californian species of Synidotea were reviewed by Menzies & Miller (1972), who also included a biogeographic account of the genus that, at the time, contained 36 species. The phylogeny and biogeography of the 22 idoteid genera, including Syni-dotea, were discussed by Brusca (1984). Poore (2001) redefined and inferred the phylogeny of the families within the Val-vifera. Most Synidotea species occur in the Arc-tic and in boreal waters (39 of the 57 de-scribed species); 13 species have been de-scribed from tropical/subtropical waters. To date, only one other Synidotea species has been described from the islands of the trop-ical Pacific, S. pacifica Nobili, 1906 from the Tuamotu Islands. Synidotea oahu n. sp. is one of only 29 marine isopods known from the Hawaiian islands (see Table 2). The only other known Hawaiian valviferan is Colidotea edmondsoni Miller, 1940. Nine species in this genus belong to the Synidotea hirtipes species-group (Monod 1931, Menzies & Miller 1972): S. hirtipes (H. Milne Edwards, 1840), S. laevidorsalis (Miers, 1881), 5. laticauda Benedict, 1897, S. harfordi Benedict, 1897, S. marplatensis Giambiagi, 1922, S. brunnea Pires & Mor-eira, 1975, S. keablei Poore & Lew Ton, 1993, S. grisea Poore & Lew Ton, 1993, and S. oahu n. sp. Members of the S. hir-tipes species-group share the following dis-tinguishing characters: pereon smooth, frontal margin of head entire or slightly ex-cavate, and posterior border of pleotelson with median excavation. Because S. oahu n. sp. possesses these characters I herein consider it a member of this group. Species boundaries within the S. hirtipes group have been disputed in the literature. Chapman & Carlton (1991, 1994) argued that S. laevi-dorsalis is a widespread species, which has been widely introduced to many coastlines from Japan by the shipping industry. Chap-man & Carlton (1991, 1994) have thus sug-gested the synonymy of seven of the nine species within this group. However, their taxonomic justification for the synonymies
Specimen codes extracted from OCR text.
BioStor
