Bioacoustics of Ryssonotus

1 Mandible with 4 scissorial teeth; tibiotarsus reduced to short lobe, length = width at base; raster setae outwardly directed............................................................................ Ryssonotus nebulosus ( Kirby, 1819 ) - Mandible with 5 scissorial teeth ( Fig. 64 ); tibiotarsus not reduced, length about 3x width at base ( Fig. 66 ); mid raster setae posteriorly or inwardly directed ( Fig. 67 ) ( Safrina )............................................................. 2 2(1) Apex of third antennomere truncate or almost so; middle of raster with elongate spines or setae....................... 3 - Apex of third antennomere, at large oval sensilla, produced as a rounded lobe beyond base of fourth antennomere; middle of raster with dense short spines, posteriorly and inwardly directed (apex of metatrochanter rounded, stridulatory file not reaching apex)....................................................................... S. jugularis ( Westwood, 1863 ) 3(2) Apex of metatrochanter angulate and stridulatory file reaching apex at this point, with 17−23 tubercles................. 4 - Apex of metatrochanter rounded and stridulatory file not reaching apex, with 15−17 tubercles (mesocoxal stridulatory file with 35−37 small granules or tubercles; fourth antennomere length to width ratio about 2.3)......... S. laticeps ( Macleay, 1885 ) 4(3) Mesocoxal stridulatory file with 33−36 small granules or pegs; fourth antennomere more elongate, length to width ratio 2.6−3.3............................................................................................. 5 - Mesocoxal stridulatory file with c.26−30 small granules or pegs; fourth antennomere less elongate, length to width ratio 2.1−2.3............................................................................ S. grandis ( Lea, 1915 ) 5(4) Inner edge of left mandible with deep excavation between bilobed apex of mola and middle of mola; inner margin of antennomere 3 deeply concave............................................................... S. polita ( Carter, 1921 ) - Inner edge of left mandible without excavation between bilobed apex of mola and middle of mola; inner margin of antennomere 3 shallowly concave.............................................................. S. moorei new species .