| abstract | The present paper gives detailed descriptions of two new species of chigger mites belonging to the genus Helenicula, parasitic on rats from Anhui and Yunnan Provinces.
Helenicula rectangia, sp. nov.
Idiosoma of unengorged larvae 420µ long and 280µ wide. Basal segment of chelicera wide. Cheliceral claw with a tricuspid cap, galeal seta nude. Palpal setae B/B/B.B.B. One large dorsal and four ventral plumose setae and one additional tarsala on tarsus. Palpal claw 3-forked. Scutum punctate, nearly rectangular shaped, ratio of AW to SD approximately 1:1. Standard measurements of holotype: AW=44.3, PW=51.4, SB=7.9, ASB=25.7, PSB=18.6, AP=28.6, AM=28.6, AL=45.7, PL=28.6, S=?. Eyes: 2+2, with ocular plate, anterior eye rounded and posterior eye indistinct. Dorsal setae plumose, longest one 15.7µ in length, arranged as follows: 2-8-6-7-10-6-10-9-5-4=67. Two pairs of plumose sternal setae; the first pair between coxae I, the another between coxae III. 58 ventral setae behind coxae III. Length of legs (ex-cluding coxae): I 176µ, II 143.3µ, III 182.6µ. Tarsus with tarsala at its middle part, microtarsala slightly behind it.
Holotype and 1 paratype, larvae, collected from ears of Apodemus agrarius in December, 1961, from Anhui Province.
Helenicula rectangia, sp. n. can easily be distinguished from other known species of the genus by the nearly rectangular shaped scutum, while those in all other species are distinctly broader than long.
Helenicula litchia, sp. nov.
Idiosoma of unengorged larvae 211.2µ long and 149.3µ wide. Chelicera with basal segment almost elongate triangular, tricuspid cap distinct, galeal seta plumose. Palpal setae B/B/B.B.B. One dorsal and four ventral plumose setae and one additional tarsala on tarsus. Palpal claws 3-forked. Scutum narrow, nearly trapezoid in shape, surface sparsely and indistinctly punctated. Anterior median seta stout, far away from anterior margin. Sensilla "litchi" shaped, with anterior ridge distinct. Standard measurementsof holotype: AW=51, PW=66, SB=10, ASB=34, PSB=13, AP=25, AM=28, AL=50, PL=55, S=?, (head: 16/20). Eyes: 2+2, with ocular plate. Dorsal setae about 100 in number, plumose. Except the first three rows, other rows with setae irregularly arranged, longest one 29µ in length. Sternal setae 2-2, coxal setae 1-1-1. Ventral setae about 80 in number. Length of legs (excluding coxae): I 192µ, II 156µ, III 207µ.
Holotype, larva, collected from Rattus flavipectus in November, 1961, from Yunnan Province. Paratypes; 4 larvae, collected from the same locality and at the same time as holotype.
Helenicula litchia, sp. n. is most closely related to H. comata (Womersley, 1952) and H. kohlsi (Philip et Woodward, 1946), but with "litchi" shaped sensilla, longer ASB and AL, prominent forked palpal prong, and about 100 dorsal and 80 ventral setae. |