Quadrimaera Krapp-Schickel & Ruffo, 2000

[Japanese name: Kaku-sunnariyokoebi-zoku, new]

Quadrimaera Krapp-Schickel & Ruffo, 2000: 194 .— Krapp-Schickel, 2008: 25.— Lowry & Myers, 2013: 36.

Type species. Gammarus quadrimanus Dana, 1853, monotypy.

Emended diagnosis. Body smooth. Head, rostrum obsolescent, lateral cephalic lobe rounded, antennal sinus distinct; eyes oval or rounded. Antenna 1, peduncular articles 1–2 longer than article 3, accessory flagellum with 4– 12 articles. Mandible, molar developed; palp articles 2–3 longer than article 1, article 1 lacking distal tooth. Maxilla 1, inner plate longish oval or bullet-shaped, palp 2-articulate. Coxae short, anteroventral corner of coxa 1 rounded or produced acutely, coxae 5–6 lobate; gills present on coxae 2–6, oostegites present on coxae 2–5. Gnathopod 1 smaller than gnathopod 2, subchelate; carpus longer than propodus, anterior margin usually with shallow excavation; propodus roundish trapezoidal, palm oblique. Gnathopod 2 very large in both sexes, symmetrical, subchelate; carpus short, lobate; propodus usually subrectangular; palm usually transverse, defined by tooth, palmar margin with 1–2 middle and 0–1 posterior excavations; dactylus with single seta on anterior margin. Pereopods, dactyli bifid; pereopods 3–4 slender; pereopods 5 – 7, bases expanded, each with posterodistal lobe, meri relatively broad, meri–propodi setose anteriorly and posteriorly. Pleonal epimeron 3 projected posteroventrally. Uropods biramous; uropod 1 peduncle usually with basofacial and distolateral robust setae, uropod 2 about 0.6–0.8 times length of uropod 1, outer rami of uropods 1–2 shorter than inner rami, both rami with marginal and distal robust setae; uropod 3, rami subequal in length, outer ramus 0.9 – 2.3 times as long as peduncle, distal margins of rami truncate, usually with long setae, longest distal seta of outer ramus 0.2 – 1.2 times as long as outer ramus. Telson deeply cleft, distal margins of each lobe truncate or incised, bearing a few to many robust setae, longest seta about 0.2 – 1.4 times length of telson.

Included species (36 species, three species in brackets are dubious and are discussed in “Remarks”). Quadrimaera ariadne (Krapp, Marti & Ruffo, 1996); Q. ariel (Ruffo, Krapp & Gable, 2000); [ Q. ascensionis (K.H. Barnard, 1932)]; Q. aurora (Krapp, Marti & Ruffo, 1996); Q. brownorum Hughes, 2015b; Q. caliban (Ruffo, Krapp & Gable, 2000); Q. carla Krapp-Schickel & Jarrett, 2000; Q. ceres (Ruffo, Krapp & Gable, 2000); Q. chaelata Senna & Serejo, 2007; Q. chinarra (J.L. Barnard, 1979); Q. cristianae Krapp-Schickel & Ruffo, 2000; Q. franzi Krapp-Schickel & Ruffo, 2006; [ Q. frater Myers, 2014]; Q. gotoensis sp. nov.; Q. gregoryi Hughes, 2015b; Q. inaequipes (Costa, 1851); Q. incerta (Chilton, 1883); Q. kaiulani (J.L. Barnard, 1970); Q. massavensis (Kossmann, 1880); Q. metinaro Hughes, 2015a; Q. micheli Appadoo, Myers & Fagoonee, 2002; Q. miranda (Ruffo, Krapp & Gable, 2000); Q. mirandella Appadoo, Myers & Fagoonee, 2002; Q. pacifica (Schellenberg, 1938); Q. pieteri Krapp-Schickel & Ruffo, 2000; Q. quadrimana (Dana, 1853); Q. reishi (J.L. Barnard, 1979); Q. rocasensis Senna & Serejo, 2007; Q. santiniae Krapp-Schickel & Ruffo, 2006; Q. sarae Krapp-Schickel & Ruffo, 2000; Q. schellenbergi (Ruffo, 1938); Q. serrata (Schellenberg, 1938); Q. setibasis sp. nov.; Q. vallaris Hughes, 2015b; [ Q. vigota (J.L. Barnard, 1969)]; Q. viridis (Haswell, 1879) .

Remarks. Krapp-Schickel (2008) enumerated 28 species in this genus. In the above list, Q. kaiulani and recently or newly described species are added. Although she indicated Q. kaiulani as a synonym of Q. pacifica, the former is quite different from the latter in the rounded palm of the gnathopod 2 and the telson with distally incised lobes. The following three species are probably included in the other genera because of their heterogeneous characters (in brackets): Q. ascensionis [strongly oblique palm of gnathopod 2 lacking posterodistal tooth (K.H. Barnard 1932, Krapp-Schickel 2004)], Q. frater [mandibular palp article 1 with distal tooth (Myers 2014)] and Q. vigota [reniform eyes, palmar margin of gnathopod 2 with several blunt teeth, and simple dactyli of pereopods (J.L. Barnard 1969, Krapp-Schickel & Jarret 2000)]. The last species should be removed to the genus Orientomaera .