Riscus
Creators: name: Heyer, Jacob Den
name: Castro, Tatiane Marie Martins Gomes De
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Prostigmata
Cunaxidae
Riscus

description: Key to Neotropical Cunaxinae (and species of Riscus).
1. Setae f2 lacking; tarsal lobes small to medium size; para-anal setae lacking; palpal telofemur with dorsal simple, tactile seta (sts); dorsal shield either smooth or with reticulated patterns; leg trichobothria absent or present; articulation facet between palpal telofemur and genu either functional or non-functional and fused............................... Cunaxini ..... 2
- Setae f2 present; tarsal lobes medium size to prominent; para-anal setae present; palpal telofemur with dorsal spine-like seta; dorsal shield always reticulated; trichobothria on tibiae IV always present; articulation facet between palpal telofemur and genu always functional............................................................. Armascirini ......... 5
2. Palpal telofemur without apophyses; sensillae densely pilose; dorsal shield without reticulated patterns; dorsal hysterosomal shield presen......................................................................................... 3
- Palpal telofemur with one or more apophyses; sensillae not densely pilose; dorsal shield with reticulated patterns; no dorsal hysterosomal shield...................................................... Rubroscirus denmarki (Smiley, 1992)
3. Trichobothrium present on tibia IV; setae hg4 behind imaginary line connecting setae hg3............................ 4
- Trichobothrium absent on tibia IV; setae hg4 anteriad to hg3 and on hypostome.............................................................................................. Cunaxatricha tarsospinosa Castro & Den Heyer, 2008
4. Articulation joint between palpal telofemur and palpal genu completely functional; 4 or 5 pairs of g-setae Riscus .......... 6
- Articulation joint between palpal telofemur and palpal genu fused and non-functional; 4 pairs of g-setae........ Allocunaxa ...................................................................... A. heveae Den Heyer & Castro, 2008
5. Palpal basifemur with a dorsal simple tactile (st) seta; st-seta formula for coxae II-IV is 1(male) or 2(female)-3-3; famulus on tarsus I normal; palpal apophyses in females usually sharp-pointed and relatively long, in males much shorter or absent; tibia I less than twice the length of genua...................... Armascirus ....................................... 7
- Palpal basifemur with a dorsal spine-like seta; st-seta formula for coxae II-IV 3-3-3; tarsus I with an everted, broad-based, distally tri-pronged famulus; palpal apophyses in females of near equal length and ending mostly with bulbous apices; tibia I more than twice the length of genua................................... D. saopauloensis Den Heyer & Castro sp.nov.
6 Five pairs of genital setae; tibia IV with 1 T, 3 sts; tibia II with 1 asl, 4 sts. R. austroamericanus Den Heyer & Castro sp.nov.
- Four pairs of genital setae; tibia IV with 1 T, 4 sts; tibia II with {1 asl, 1sts}, 4 sts........ R. thailandensis Den Heyer, 2006
7 Without lateral hysterosomal shields.................................................... A. bison (Berlese, 1888)
- With lateral hysterosomal shields......................................................................... 8
8 Males tibia I with 1 stout bsl, {1 asl, 1 sts}, 4 sts (Figs. 27-30); males with stout bsl on genua III and IV; females with median hysterosomal shield carrying setae e1 or nearly reaching this seta pair.......... A. bahiaensis Den Heyer & Castro sp. nov.
- Male tibia I with 1 bsl, {1 asl, 1sts}, 4 sts (Figs. 13&14); males with ordinary asl on genua III and IV; females with small dorsal median hysterosomal shield with or without seta d1...................... A. brasiliensis Den Heyer & Castro sp. nov.
description: Published as part of Heyer, Jacob Den & Castro, Tatiane Marie Martins Gomes De, 2012, New Neotropical cunaxine species (Acari: Prostigmata: Cunaxidae), pp. 22-42 in Zootaxa 3265 on page 40, DOI: 10.5281/zenodo.280740