Riscus

Heyer, Jacob Den & Castro, Tatiane Marie Martins Gomes De, 2012, New Neotropical cunaxine species (Acari: Prostigmata: Cunaxidae), Zootaxa 3265, pp. 22-42 : 40

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.

Figures

FIGURES 26 – 30. Armascirus bahiaensis Den Heyer & Castro sp. nov. Male. Chelicera (26); leg I (27); leg II (28); leg III (29); leg IV (30). UMB = 100 μm.

FIGURES 13 – 16. Armascirus braziliensis Den Heyer & Castro sp. nov. Male. Leg I (13); leg II (14); leg III (15); leg IV (16). UMB = 100 μm.