Status of Exosphaeroma amplicauda (Stimpson, 1857), E. aphrodita (Boone, 1923) and description of three new species (Crustacea, Isopoda, Sphaeromatidae) from the north-eastern Pacific

Abstract

Exosphaeroma amplicauda (Stimpson, 1857) from the west coast of North America is reviewed and redescribed and revealed to be a group of closely related species. A neotype is designated and the species redescribed based on the neotype and topotypic specimens. Exosphaeroma amplicauda is known only from the coast of California, at Marin, Sonoma and San Mateo Counties. Exosphaeroma aphrodita (Boone, 1923), type locality La Jolla, California and previously considered nomen dubium is taken out of synonymy and re-validated. A further three species: Exosphaeroma paydenae sp. n., Exosphaeroma russellhansoni sp. n., and Exosphaeroma pentcheffi sp. n. are described herein. Sphaeroma octonctum Richardson, 1899 is placed into junior synonymy with Exosphaeroma amplicauda. A key to the Pacific West Coast Exosphaeroma is provided.

Redescription of Gnorimosphaeroma oregonense (Dana, 1853) (Crustacea: Isopoda: Sphaeromatidae), designation of neotype, and 16S-rDNA molecular phylogeny of the north-eastern Pacific species

“…Along the Washington to California coast this species commonly co-occurs with Exosphaeroma inornata Dow, 1958. The latter is known from Puget Sound, Washington to central-southern Baja California Norte, Mexico (Wall et al 2015). When specimens are very small and/or subadults, not only do the species of Gnorimosphaeroma get readily confused, but sometimes they are misidentified as E. inornata if not the most careful attention is paid.…”

“…10, 11). Our Exosphaeroma amplicauda (Wall et al 2015) review resulted in the recognition of five species with Alaska and Washington specimens recognized as distinct from the type locality (Central California), and distinct from those from the Southern California coast. It would not be surprising if future studies based on broader sampling revealed greater genetic diversity than what we observed here.…”

“…see Bruce 2003;Espinosa-Pérez & Hendrickx 2001;Kensley 1978), and also species with greatly enlarged uropodal rami (e.g. see Bruce 2003;Kensley 1978;Wall et al 2015). Some of the smooth-bodied species of Exosphaeroma are superficially similar to Gnorimosphaeroma, but can be distinguished by the pleonal sutures running to the posterior margin (to the free lateral margin in Gnorimosphaeroma), as well as pleonite 1 having two flat sub-median lobes on the posterior margin (see Bruce 2003, figs.…”

Tricarina gadvanensisis an isopod: reinterpretation of an alleged lobster from the Lower Cretaceous of Iran

“…In many sphaeromatideans, the anterior pleonites often are partly overlapped or concealed completely by the last pereonite (Jacobs, 1987; Wall et al, 2015). In addition, some pleonites may be overlapped by other pleonites (Bruce, 1986; Brusca et al, 2007).…”

Redescription of Dynoides elegans (Boone, 1923) (Crustacea, Isopoda, Sphaeromatidae) from the north-eastern Pacific

“…Specimens are prepared for SEM as described in Wall et al (2015). Drawings were made with the aid of a camera lucida and illustrations were electronically “inked” with Affinity Designer, Serif Labs.…”