Quadrimaera Krapp-Schickel & Ruffo, 2000

Ariyama, Hiroyuki, 2019, Species of the Maera - clade collected from Japan. Part 2: genera Austromaera Lowry & Springthorpe, 2005 and Quadrimaera Krapp-Schickel & Ruffo, 2000 (Crustacea: Amphipoda: Maeridae), Zootaxa 4554 (2), pp. 460-496 : 468

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 .