Seba Bate, 1862

Ariyama, Hiroyuki, 2009, Four species of the genus Seba from Japan, with descriptions of two new species (Crustacea: Amphipoda: Sebidae), Zootaxa 2159, pp. 44-68 : 44-45

Genus Seba Bate, 1862

Seba Bate, 1862: 159 (type species: Seba innominata Bate, 1862 by monotypy).— Stebbing, 1888: 782.— Della Valle, 1893: 773.— Stebbing, 1906: 162. – Walker, 1907: 37.— Schellenberg, 1931: 83.— J.L. Barnard, 1969: 436.— Karaman, 1971: 73.— Holman & Watling, 1983: 239.— Ledoyer, 1986: 944.— Shaw, 1989: 1885.—J.L.

Barnard & Karaman, 1991: 668.— Karaman, 1993: 681.— Lowry & Stoddart, 2003: 250. Teraticum Chilton, 1884: 257 (type species: Teraticum typicum Chilton, 1884 ).

Grimardia Chevreux, 1889: 284 (type species: Grimardia armata Chevreux, 1889 ).

Paravalettia K.H. Barnard, 1916: 112 (type species: Paravalettia chelata K.H. Barnard, 1916 ). Caribseba Shaw, 1989: 1885 (type species: Seba tropica McKinney, 1980 ).

Diagnosis [modified from J.L. Barnard & Karaman (1991)]. Body compressed, smooth or weakly carinate; urosomites 2 and 3 coalesced (except for Seba aloe Karaman, 1971 ). Rostrum obsolete, lateral lobes well developed, eyes absent [except for S. typica ( Chilton, 1884) ]. Antennae 1 and 2 of medium length, extending equally; peduncle of antenna 1 long, articles 1 and 2 longer than article 3; accessory flagellum present (except for S. tropica ), 2-articulate, article 2 tiny; flagella of both antennae short. Mandibular incisor developed, toothed, molar reduced; palp long, with 3 articles, article 2 elongate, article 3 with 1–3 (mostly 2) apical setae. Labium with well-developed mandibular lobes, inner lobes indistinct. Maxilla 1 with blunt inner plate bearing 0–2 apical setae, outer plate with 7 apical setae; palp elongate, 1-articulate, with 1–4 apical setae. Maxilla 2 formed of weakly setose similar plate, outer plate bearing 3–5 setae. Plates of maxilliped moderately developed, poorly setose; palp stout, 4-articulate, dactylus unguiform. Coxae 1–4 of medium length, coxa 4 poorly excavate posteriorly; coxae 5–7 moderately shortened. Gnathopod 1 weakly chelate or subchelate; carpus short, lobed; propodus broad. Gnathopod 2 slender, strongly chelate; ischium elongate; carpus long, unlobed; propodus elongate, forming a chela with fitted dactylus. Pereopods 3 and 4 similar, ordinary; pereopods 5–7 relatively similar to each other, bases expanded, meri often expanded and lobate. Coxal gills present on pereopods 2 or 3 to 6, oostegites of female on pereopods 2–5. Pleopods ordinary. Uropods 1 and 2 biramous, stout, weakly spinose or almost naked, outer rami subequal or slightly shorter than inner rami; uropod 3 uniramous, peduncle short, ramus much longer than peduncle, 2-articulate. Telson linguiform, longer than broad, entire, poorly setulose. Sexual dimorphism often present in gnathopod 1 and pereopods 5–7.

Remarks. Walker (1907) proposed to call the genus Seba Stebbing, 1875 , with Seba saundersi Stebbing, 1875 as the type species, because the existence of S. innominata had been questioned ( Stebbing, 1888; Della Valle, 1893); Karaman (1971) approved of the proposal, and Holman & Watling (1983) also pointed out this taxonomic problem. However, referring the International Code of Zoological Nomenclature (International Commission of Zoological Nomenclature, 1999: Articles 50.1, 67.2), Bate’s (1862) nomenclature is valid.

Shaw (1989) presented the following characters for the diagnosis of the new genus Caribseba : (1) antenna 1 without accessory flagellum, (2) inner plate of maxilla 1 without apical seta, and (3) mandibular palp segment 3 with single apical seta. Although only Carib s eba tropica , the type species of the genus, actually has the character (1) in the species of the genera Seba and Caribseba , the characters (2) and (3) are shared with some of the Seba species as Winfield et al. (2009) stated [character (2): S. alvarezi , S. ekepuu J.L. Barnard, 1970 and S. robusta ; character (3): S. ekepuu and S. robusta ]. Moreover, there are wide morphological variations in the genus Seba [e.g. the presence of eyes in Seba typica , and the separated urosomites 2 and 3 in S. aloe ]; therefore, Caribseba should be restored to Seba .