Riscus austroamericanus Den Heyer, sp. nov.
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
Riscus austroamericanus

description: Riscus austroamericanus Den Heyer sp. nov.
Material examined: 1 female holotype, Coffea arabica L., Quillabamba, Cuzco, Peru (12° 5' 19.6” S / 72°42' 13.3” W), A.D.G. Alvarado, 04-VII-2006; 1 paratype tritonymph, Solanum nigrum L., Quillabamba, Cuzco, Peru (12° 5' 19.6” S / 72° 42' 13.3” W), A.D.G. Alvarado, 4-VII-2006; 1 paratype female, Coffea arabica L., Quillabamba, Cuzco, Peru (12° 5' 19.6” S / 72°42' 13.3” W), A.D.G. Alvarado, 04-VII-2007; 1 paratype female, Euterpe sp., Recife, Pernambuco, Brazil (8° 02' S / 40° 01' W), Gondim Jr, M. G. C., 5-I-1999, slide MZLQ 3050; 1 paratype female, 1 paratype deutonymph, Pisidium guajava Ilhéus, Bahia, Brazil (13° 01'S / 40° 01'W), 31-VII-2007, A.R. Oliveira.
Description.
Female (Figs. 39–48) Dimensions. Idiosoma: length 394 (335–443); width 287 (246–300); length hypognathum 128 (108–135); width hypognathum 80 (77–85); length palp 108 (96–117); length chelicera 114 (94–137); length legs I 241 (219–270); II 246 (223 -285); III 287 (235–304); IV 308 (289–320); length sensillae vi 125 (116–135) and sce 155 (139–158).
Dorsum (Fig. 39 a,b & 41 a–c). The demarcation of the propodosomal shield is very vague (Fig. 39 a & b). The same is true for the integumental striae. Only one very finely reticulate propodosomal shieldlike area (Fig. 41 a) on the idiosoma: it bears setal pairs ve and sci as well as sensilla pairs vi and sce (Figs 41 b&c, respectively); the latter are the longest sensillae. Except for setae sci all dorsal setae are rather short. Setae h1 are the longest hysterosomal setae.
Venter (Fig. 40 a, b). As with the dorsum hysterogastral “shields” and striae are poorly defined. Setae pcs (= paracoxal seta) occur on the median margin of coxae IV. Three pairs of hysterogastral setae. The genital area (Fig. 42) is recognised by the 5 pairs of g-setae. A pair of paragenital setae occur laterally to the anterior half of the genital region. The chelicera possesses a near terminal seta. The length ratio width:length of the hypognathum is 1: 1.5
Hypognathum (Fig. 43). The coxal region is finely papillate whereas the hypostome is longitudinally striate. Setae hg1 are short and immediately posteriad the entomalae with its 4 small adoral setae; setae hg2–4 are long; setae hg4 are situated medially to setae hg3 forming a nearly straight transverse row (Fig. 43).
Palp (Fig. 44) reaches past the entomalae with nearly the entire length of its tibiotarsusus. Its chaetotaxy is as follows: trochanter, 0; basifemur, 1 sts shorter than the segment; telofemur, 1 dorsal sts; genu, 2 sts, 1 strong, curved sts proximally and 1 straight spine-like sts; tibiotarsus, 1 ventral sts, 1 very strong median tubercle, 2 sts, 1 tsl, 1 claw. The palpal segments are finely papillate.
Legs (Figs. 45–48). Leg chaetotaxy: coxae I – IV 3 sts, 1 peg – 1 sts – 3 sts – 1 sts; trochanters I – IV 1 – 1 – 2 – 1 sts; basifemora I – IV 3 – 3 – 2 – 1 sts; telofemora I – IV 4 – 4 – 4 – 4 sts; genua I – IV {2 asl}, {1 asl, 1 sts}, 1 longish asl, 4 sts – 2 asl, 5 sts – 1 asl, 5 sts – 1 asl, 5 sts; tibiae I – IV {2 asl, 1 sts}(Fig 45 b), 4 sts – 1 asl, 5 sts – 1 bsl, 5 sts – 1 T, 3 sts; tarsi I – IV 3 asl, {1 asl, 1 sts, 1 fmls}, 1 dtsl, 2 tsl, 15 or 16 sts – 1 bsl, 1 dtsl, 1 tsl, 16 or 17 sts – 1 tsl, 14 or 15 sts – 15 or 16 sts.
Remarks. Differences between the two known species of Riscus shown in Table 4.
*All kinds (= bsl, asl); **micrometers
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 pages 36-38, DOI: 10.5281/zenodo.280740