Bioacoustics of Eterosonycha

Description . Very small, entelegyne Araneoidea : total length 0.80 to 1.20. Cephalothorax : Carapace without glandular depressions above maxillae; cuticle without glandular pits ( Fig. 56A ). Eight eyes present on anterior margin of pars cephalica ( Fig. 52C ); AME smallest. Chelicerae with bulging anterior projections in males; promargin with inner denticles, true teeth, a pair of fused setal sockets adjacent to base of fang and three peg teeth in males ( Fig. 57H ); ectal stridulatory ridges present in males ( Fig. 59A ). Legs and female pedipalp : Legs three-clawed ( Fig. 58F ), covered with smooth or serrate hair-like setae; tibia I of males with distal, prolateral macroseta ( Figs 59 C–D). Trichobothria present on legs; tibiae each with three (legs I–III) or four (leg IV) trichobothria; metatarsi (legs I–III) each with single trichobothrium ( Fig. 58C ). Female pedipalp entire, five-segmented; claw absent ( Fig. 57E ). Abdomen : Abdomen oval; anterior sclerite present around epigastric region and petiole; large dorsal scute present on males ( Fig. 54A ), absent on females ( Fig. 54B ); posterior sclerotic ring surrounding spinnerets weakly-sclerotised. Six spinnerets situated posterior to fleshy colulus (Fig. 71A); PMS of E. alpina with single medial AC gland spigot; PLS of E. alpina with complete triad, including enlarged, sinuous FL gland spigot. Anterior tracheal system with multiple anteriorly-directed tracheae (Fig. 51B); posterior tracheal spiracle absent. Genitalia : Male pedipalp ( Fig. 60 ) relatively large; trochanter with modified prolateral seta forming stridulatory ‘tooth’; patella distally-expanded, with retrolaterallydirected, hooked ligulate retrolateral apophysis and ornate, ridged cuticular microstructure; tibia modified, enlarged, with one or more posterior processes; tegulum large, bulging posteriorly, with excavate evaginated tegular ridge and large, fleshy distal conductor with two divergent processes; embolus exposed, short (length <5× width) and spur-like. Female genitalia (Fig. 51) heavily sclerotised externally, with pair of separate, ‘twisted’ anterior spermathecae; insemination ducts heavily sclerotised, curving anteriorly; fertilisation ducts filiform.