Maeridae Krapp-Schickel, 2008a

Lowry, J. K. & Hughes, L. E., 2009, Maeridae, the Elasmopus group *, Zootaxa 2260 (1), pp. 643-702 : 644

Maeridae Krapp-Schickel, 2008a

Several authors ( Bousfield 1973, 1977; J.L. Barnard 1972a; Barnard & Barnard 1983; Lowry & Watson 2002; Krapp-Schickel 2009) have discussed groups within the Melitidae Bousfield, 1973 . Krapp-Schickel (2008a) formalised one of these groups in the newly established family Maeridae Krapp-Schickel, 2008a . The Maeridae was not fully defined, however, with only one character and two character states given to separate it from the Melitidae (sensu lato). Twenty-six genera were listed for the family ( Krapp-Schickel 2008a), with an acknowledgement that more genera might await inclusion. In this paper we present a diagnosis that separates the Maeridae from all other amphipod families and we include 40 genera.

Diagnosis. Body laterally compressed or sub-vermiform. Head anteroventral corner with notch/slit or anteroventral corner excavate. Antennae 1–2 without calceoli. Antenna 1 longer than antenna 2. Antenna 2 without bulbous article 1. Mandible molar well developed. Coxal gills not stalked. Urosomites 1–3 free. Urosomite 2 without dorsal robust setae. Uropods 1–2, apices of rami with robust setae. Uropod 1 peduncle with basofacial robust seta. Uropod 3 biramous, inner ramus at least half length of outer ramus; outer ramus 1– or 2–articulate, with article 2, when present, short or long, never greatly elongate. Telson laminar.

Included genera. Maeridae includes 40 genera: Anamaera Thomas & Barnard, 1985a ; Anelasmopus Oliveira, 1953 ; Animoceradocus G. Karaman, 1984 ; Austromaera Lowry & Springthorpe, 2005 ; Bathyceradocus Pirlot, 1934 ; Beaudettia J.L. Barnard, 1965 ; Ceradocoides Nicholls, 1938 ; Ceradocopsis Schellenberg, 1926 ; Ceradocus Costa, 1853 ; Ceradomaera Ledoyer, 1973 ; Coxomaerella G. Karaman, 1981 ; Dumosus Thomas & Barnard, 1985b ; Elasmopoides Stebbing, 1908 ; Elasmopus Costa, 1853 ; Glossomaera Krapp-Schickel, 2009 ; Hamimaera Krapp-Schickel, 2008a ; Hoho Lowry & Fenwick, 1983 ; Ifalukia J.L. Barnard, 1972a ; Jerbarnia Croker, 1971 ; Linguimaera Pirlot, 1936 ; Lupimaera Barnard & Karaman, 1982 ; Maera Leach, 1814 ; Maeracoota Myers, 1997 ; Maeropsis Chevreux, 1919 ; Mallacoota J.L. Barnard, 1972a ; Megaceradocus Mukai, 1979 ; Metaceradocoides Birstein & Vinogradov, 1960 ; Meximaera Ledoyer, 1983 ; Othomaera Krapp-Schickel, 2000 ; Paraceradocus Stebbing, 1899 ; Parelasmopus Stebbing, 1888 ; Pseudelasmopus Ledoyer, 1978 ; Quadrimaera Krapp-Schickel & Ruffo, 2000 ; Quadrivisio Stebbing, 1907 ; Ruffomaera Krapp-Schickel, 2008b ; Saurodocus Yerman & Krapp-Schickel, 2008 ; Spathiopus Thomas & Barnard, 1985a ; Thalassostygius Vonk, 1990 ; Wimvadocus Krapp-Schickel & Jarrett, 2000 ; Zygomaera Krapp-Schickel, 2000 .

Remarks. Now that the Maeridae Krapp-Schickel, 2008a is recognised as distinct from the Melitidae Bousfield, 1973 , it becomes apparent how morphologically similar the genera of Maeridae are to those of the freshwater family Hadziidae S. Karman, 1943 . Although hadziids generally have differently shaped gnathopods, third uropods and telsons from maerids, the only character we can currently find to separate the two families definitively, is the stalked gills (with partial or complete proximal diaresis) of the Hadziidae .

Most genera fit well within the definition of the Maeridae . Barnard & Barnard (1983) listed Parapherusa in their ‘ceradocid’ group. We exclude it from the Maeridae because the second antennae are slightly longer than the first, the anteroventral corner of the head is rounded and entire, the first gnathopods are apparently sexually dimorphic and the peduncle of uropod 1 has a distoventral spine and does not have a basofacial robust seta. Until there is a phylogeny which takes into account all of the ‘hadzioid’ taxa the family level structure will remain problematic.