Records of the Western Australian Museum 17: 443-446 (1996). 
Two new species of the water mite genus Penemideopsis from 
Western Australia (Acarina: Mideopsidae) 
Mark S. Harvey 
Western Australian Museum, Francis Street, Perth, Western Australia 6000, Australia 
Email: harveym@muswa.dialix.oz.au 
Abstract - Penemideopsis pusilla sp. nov. and P. angovensis sp. nov. are each 
described from single males collected in southwestern Australia, and 
compared with P. phreatica from Victoria. 
INTRODUCTION 
The genus Penemideopsis was described by Cook 
(1986) from a single male specimen collected from 
interstitial deposits in eastern Victoria. This 
species, P. phreatica Cook, differed from all other 
mideopsids by the combined presence of a greatly 
enlarged tubercle and seta on the pedipalpal tibia, 
the possession of only three pairs of acetabula, and 
lobes covering the openings of leg IV (Cook 1986). 
The discovery of two additional specimens of 
Penemideopsis amongst collections from Western 
Australia made available by Dr Jenny Davis 
(Murdoch University) and Dr Stuart Halse 
(Department of Conservation and Land 
Management) has significantly expanded the 
geographic distribution of the genus, and these 
species differ in small but significant ways from 
the type species. The Western Australian 
specimens are described here and compared with 
P. phreatica. 
These two new species of Penemideopsis represent 
the second genus of small, presumably interstitial, 
mideopsid reported from Western Australia. Like 
each of the species described here, the first, Tillia 
davisae Harvey, has been collected only once 
(Harvey 1990). 
The specimens are mounted on microscope slides 
in glycerol gel or Hoyers mountant, and lodged in 
the Western Australian Museum, Perth (WAM). 
Nomenclature of the leg segments follows Harvey 
(1996). 
SYSTEMATICS 
Family Mideopsidae Koenike 
Genus Penemideopsis Cook 
Penemideopsis Cook, 1986: 300. 
Type species 
Penemideopsis phreatica Cook, 1986, by original 
designation. 
Diagnosis 
Male (modified from Cook 1986) 
Pedipalp not uncate; tibia with greatly enlarged 
ventral seta set in large tubercle. Medial margins of 
coxa IV broad; projections covering openings of leg 
IV either greatly enlarged or small. Swimming 
setae absent. Males without any pronounced 
modifications of the legs, presumably indicating a 
lack of sexual dimorphism. Three pairs of 
acetabula; gonopore narrow, but bulging outwards 
in the region of the first two pairs of acetabula. 
Remarks 
The discovery of two additional species of 
Penemideopsis requires a slight alteration to the 
generic diagnosis, as the projections covering the 
openings of coxa IV range from large (P. phreatica) 
to small (P. pusilla and P. angovensis ). 
Key to species of Penemideopsis (males only) 
1. Projections covering openings of coxa IV large; 
outer coxal margins distinctly bulging. 
. Penemideopsis phreatica Cook 
Projections covering openings of coxa IV small 
(Figures 2, 8); outer coxal margins smooth 
(Figures 2, 8)...2 
2. Dorsoglandularial setae situated close to 
glandularia (Figure 1); posterior margin of 
coxa IV extending past anterior margin of 
genital field (Figure 2). 
. Penemideopsis pusilla sp. nov. 
Dorsoglandularial setae situated far mesal to 
glandularia (Figure 7); posterior margin of 
coxa IV not reaching anterior margin of 
genital field (Figure 8). 
. Penemideopsis angovensis sp. nov. 
