Systematic & Applied Acarology
ISSN 1362-1971
An international journal of the Systematic and Applied Acarology Society, published since 1996

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Systematic & Applied Acarology (2002) 7, 191-206

Revision of the sand-mite tribe Walchiini Ewing sensu Wen, 1984 (Acariformes: Walchiidae)


Medical Acarology Laboratory, Shanghai Medical University, Shanghai 200032, CHINA; E-mail:


The family Walchiidae, one of three families of the superfamily Trombiculoidea sensu Wen, contains two

subfamilies: Walchiinae sensu Wen and Gahrliepiinae sensu Wen. The subfamily Walchiinae may be further

separated into two tribes: Walchiini and Schoengastielliini. Members of the tribe Walchiini are small to medium

sized sand-mites with IP=344-800 and the following features: the scutum ranging from very small to medium

size, pentagonal or short tongue-shaped, with uniform punctae but without scrobiculae and with only two pairs

of scutal setae consistently (fSc=2AL+2PL), without accessory setae; sensillae expanded; SIF=4B/5B-N/B-3/

2-2(1)1(0)1(0)0.0000; leg segments fSP=7.6.6 wihtout variation; pedogenualae fg(s)=2.1.1 in most species;

fcx=1.1.1 or 1.1.2 in most species, but a few species with 3-6 coxalae III; some species characterized by one of

hair-like claws reduced on each leg. Currently, the Walchiini contains 92 nominated species in 2 genera and 15

subgenera (including Wenia sg. n. and Zhangzia sg. n.). The genus Walchia is characterized by fT=4B and

acuminated posterior angle, rarely rounded, whereas the genus Ripiaspichia is distinguished by fT=5B and

rounded posterior margin. Hosts of the Walchiini are chiefly small ground rodents, insectivores and lagomorphs,

rarely bats, deers and horses, and occasionally reptiles. They are pale coloured host-burrow dwellers. Two

subgenera, Fainiella and Traudia, are intranasal parasites. Walchiiine sand-mites are essentially confined to the

Old World, the largest number of species having been recorded from Southeast Asia. As yet, this tribe has not

been reported from the Neotropical Region. A key to the genera and subgenera of the Walchiini is given.

Key words: sand-mites, Walchiidae, Walchiini, systematics, new subgenera


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