Records of the Western Australian Museum 17: 361-393 (1996). 
A review of the water mite family Pionidae in Australia 
(Acarina: Hygrobatoidea) 
Mark S. Harvey 
Western Australian Museum, Francis Street, Perth, Western Australia 6000, Australia 
Email: harveym@muswa.dialix.oz.au 
Abstract - The Australian Pionidae consists of 11 species in six genera: Larri 
gen. nov. (with type species L. laffa sp. nov.), Austrulotiphys Cook (with A. 
magnisctus Cook, A. himonius sp. nov. and A, barmutai sp. nov.), Acercella 
Lundblad (with A. falcipes Lundblad and A. poorginup sp. nov.), Fiona Koch 
(with P. cumberlandcnsis (Rainbow), P. australica K.O. Viets, P. puripalpis K.O. 
Viets, P, murleyi sp. nov. and P. marclwnli sp. nov.). Mating in Acercella 
falcipes Lundblad and Piona cumberlandcnsis (Rainbow) is briefly discussed. 
INTRODUCTION 
Water mites of the family Pionidae are 
widespread throughout the Holarctic region where 
many genera are currently recognised (Cook 1974; 
Smith 1976; Simmons and Smith 1984). The fauna 
of the southern hemisphere is less well known and 
only diverse genera such as Piona Koch have been 
recorded frequently. Nevertheless, a distinct and 
very interesting Australian pionid fauna is present. 
The first described Australian species, A tax 
cumberlandcnsis Rainbow, was not recognised as a 
member of the genus Piona until 1986 (Cook 1986). 
Piona uncatiformis and Acercella falcipes were 
described by Lundblad (1941), and two further 
species of Piona were added by K.O. Viets (1980, 
1984). The enigmatic Australotiphys magnisetus 
Cook was described by Cook (1986). With the 
recent discovery of additional species of these three 
genera, as well as an undescribed genus from 
southwestern Australia, it became apparent that a 
review of the Pionidae of Australia would be 
profitable. The results of that study are presented 
here. 
MATERIALS AND METHODS 
Specimens are lodged in the following 
repositories: 
ANIC Australian National Insect Collection, 
Canberra 
AM Australian Museum, Sydney 
CNC Canadian National Collection, Ottawa 
DCC D. R. Cook collection, Detroit 
NMV Museum of Victoria, Melbourne 
QVM Queen Victoria Museum, Launceston 
SAM South Australian Museum, Adelaide 
SMNH Swedish Museum of Natural History, 
Stockholm 
TM Tasmanian Museum and Art Gallery, 
Hobart 
VC Viets private collection, Wilhelmshaven 
WAM Western Australian Museum, Perth 
Methods follow Harvey (1987). Where the 
measurements are expressed as a fraction, the 
numerator refers to the length of the structure and 
the denominator refers to its width. Abbreviations 
for glandularia follow Harvey (1987): dgl-5 refers 
to the dorsoglandularia series, lgl-4 refers to the 
lateroglandularia series, and vgl-5 and vgx refers 
to the ventroglandularia series. Unless otherwise 
stated, the body colour is of specimens fixed and 
stored in Koenike's solution (Cook 1974), and 
refers to the sclerotized portions of the body (e.g., 
legs, coxae), rather than the soft portions. Those 
specimens denoted as 'SL' are mounted on slides, 
while those denoted as 'FL' are retained in fluid. 
The terminology of water mite pedipalp and leg 
segments has been inconsistently applied by 
various workers. I here propose to alter the system 
that I have previously employed to name the leg 
segments, and replace them with names used in 
other arachnid groups (e.g. Shultz 1989, 1990; 
Harvey 1992), thus providing consistency within 
the class. Nearly all arachnids have six segments in 
the pedipalp (coxa, trochanter, femur, patella, tibia 
and tarsus), and seven segments in the legs (coxa, 
trochanter, femur, patella, tibia, metatarsus and 
tarsus) which clearly points to the homologous 
nature of leg segmentation within the Arachnida. 
SYSTEMATICS 
Family Pionidae Thor 
Remarks 
Recent diagnoses and classifications of the 
Pionidae (Cook 1974; Smith 1976) have emphasised 
