Primagistemus, Fan & Zhang, 2002

Fan, Qing-Hai & Zhang, Zhi-Qiang, 2002, Primagistemus gen. nov. (Acari: Prostigmata: Stigmaeidae), Zootaxa 29, pp. 1-8 : 2-3

Genus Primagistemus gen. nov.

Type species: Stigmaeus loadmani Wood, 1967: 102 ; based on adult females.

Description of adults ( Figs. 1­17 ). Idiosoma oval in dorsoventral view. Chelicerae separate. Palp robust; tibial claw slightly shorter than palptarsus; accessory claw slender. Terminal palptarsal eupathidia fused basally at insertion point and distally divided into 3 minute prongs. Fundamental setation from palptrochanter to palptarsus on adult: 0, 3, 1, 2 + 1 claw + 1 accessary claw, 4 + 1 1 subterminal spine­like eupathidium + 3 basally fused eupathidia. Subcapitulum with 2 pairs of setae (m and n), both posterolaterad of pharynx, m­m wider than n­n. Propodosoma covered with a large triangular shield, which bears 1 pair of eyes and 4 pairs of setae (vi, ve, sci, sce), sci mediad of sce; postocular body absent. Central hysterosomal shield well sclerotized, bearing 3 pairs of setae (c1, d1, e1). Setae c2, d2, e2 and f1 situated on small platelets. Suranal shield (H) integral, bearing 2 pairs of setae (h1 and h2). Endopodal shields present around coxae I and II, but absent around III and IV. Ventral setae 3 pairs (1a, 3a and 4a). Aggenital setae 3 pairs (ag1, ag2 and ag3). Genital and anal openings contiguous, with 1 pair of genital setae (g1) and 3 pairs of pseudanal setae (ps3, ps2 and ps1) on adult female. Leg tarsal claws well developed, without a prominent membranous arolium. Empodium rod­like, bearing 3 Y­shaped tenent hairs. Fundamental setation of legs I­IV on adult female: coxae 2, 1, 2, 2; trochanters 1, 1, 1, 0; femora 5, 4, 3, 2; genua 3 + 1, 2, 0, 0; tibiae 5 + 1p, 5 + 1 p, 5 + 1 p, 5 + 1 p; tarsi 13 + 1, 9 + 1, 7 + 1, 7 + 1.

Etymology. The generic name Primagistemus is combined from the Latin prefix “ primi ” (primal) and the generic name, Agistemus . It is masculine in gender.

Taxonomic position. Mites of the genus Primagistemus have 4 pairs of setae on the propodosomal shield, like those in some genera (e.g. Stigmaeus , Pseudostigmaeus , Summersiella , Eustigmaeus and Cheylostigmaeus ). However, many other characteristics (e.g., both subcapitular setae m and n posterolaterad to pharynx; palpgenu with only 1 seta on the adult, terminal eupathidia on palptarsus mostly fused, coxa II with only 1 seta; endopodal shields around coxae III­IV absent, trochanter III with 1 seta) indicate that Primagistemus is much more closely related to the genera, Agistemus , Zetzellia , Neilstigmaeus , Pilonychiopus and Parastigmaeus .

Remarks. Adult females of Primagistemus gen. nov. are distinguished from those of Agistemus by having 4 pairs of setae on the propodosomal shield, by lacking postocular bodies, by having 3 pairs of aggenital setae, and by having 2 setae on genu II. They are also distinguished from those of Stigmaeus by the terminal eupathidia on palptarsus being mostly fused and subterminally separated into 3 minute prongs, by both subcapitular setae posterolaterad of pharynx, by having only 1 seta on coxa II, and by lacking endopodal shields around coxae III­IV.

Figures

FIGURES 1­2. Primagistemus loadmani (Wood) comb. nov. (adult female). 1, dorsal view of subcapitulum and idiosoma; 2, ventral view subcapitulum and idiosoma.

FIGURES. 3­8. Primagistemus loadmani (Wood) comb. nov. (3­7, adult female; 8, deutonymph). 3, chelicerae; 4, left palp; 5, ventral view of subcapitulum; 6, genito­anal area; 7, ventral setae; 8; genito­anal area.

FIGURES 9­12. Primagistemus loadmani (Wood) comb. nov. (adult female). 9, leg I; 10, leg II; 11, leg III; 12, leg IV.

FIGURES 13­17. Primagistemus wuyiensis sp. nov. (adult female). 13, dorsal view of gnathosoma and idiosoma; 14, right palp; 15, genito­anal area; 16, dorsal setae; 17, tarsus I.