Australian Arrenurus 
253 
group of water mites has puzzled acarologists for a 
long time. K. Viets (1956) placed species of this 
group in the subgenus Micruracarus, probably 
because the presence of a median cleft in the cauda. 
Later, Cook (1957) assigned this group to the 
subgenus Megaluracams. However, species of the 
new subgenus are very different from all 
Megaluracarns species. All members of the new 
subspecies have D1 on very large humps, and 
many species have other large humps on the 
dorsum or one hump between the humps of Dl, 
which give them a very three-dimensional 
appearance. 
The following species belong to the new 
subgenus (all comb, nov.) A. lohmanni, A. 
bicornutus Piersig, A. laticodulus Piersig, A. 
matupitensis Piersig, A. quadricomutus Piersig, A. 
multicornutus Walter, A. toxopeusi K. Viets, A. 
tricomutus K. Viets, A. roobeeki Smit (all from the 
Indo-Australian region and the Pacific), A. 
imperator imperator Lundblad, A. imperator goliath 
Lundblad, A. guatemdltecus K.O. Viets, A. toriger K. 
Viets (all from the neotropics), A. gibbus Koenike, 
A. palpebratus Nordenskiold, A. dumazeri Motas, A. 
neolaticodulus Cook, A. discretus Cook (all from 
Africa). 
Arrenurus (Brevicaudaturus) lohmanni Piersig, 
comb. nov. 
Figures 35-40 
Arrhenurus Lohmanni Piersig, 1898: 572. 
Arrhenurus lohmanni Piersig: Piersig, 1903: 21. 
Arrenurus lohmanni Piersig: Cook and Bright 1983: 
198. 
Material Examined 
Australia: Western Australia: 1 S, 8 $, 
McKenzie Spring, Millstream-Chichester National 
Park, 17 August 1994 (ZMA). 
Description 
Male 
Body 1464 long, 1176 wide and 1350 high. Two 
large humps on the anterior body part not fully 
sclerotized (Figures 36, 37). The corners of the 
cauda are bluntly-pointed, but are probably not 
fully sclerotized as well (Figure 35). Lengths of PI- 
PV: 45, 113, 65, 122, 55; PII with three setae on 
medial side. Lengths of I-leg-4-6: 194, 213, 310. 
Lengths of IV-leg-4-6: 320, 291, 252. 
Female 
Body 2040 (1848-2148) long, 1608 (1464-1680) 
wide and 1824 (1632-1944) high. Body colour 
yellow. Anterior part of body with three large, 
conical humps, Dl on the two lateral humps, 
medial hump without glandularia (Figure 39); the 
humps of Dl narrowed dorsally (Figure 40), the 
medial hump of equal wide. Dorsal furrow 
complete, dorsal shield pear-shaped. Dorsal shield 
1152 long, with one pair of large humps, on which 
D4 are situated. Posterior body margin indented. 
L4 on a small hump. Coxal field small. CX4 almost 
without medial margin. Gonopore 142 long. 
Genital plates long and narrow, strongly bowed, 
extending onto lateral side of body, halfway lateral 
end of genital plates widened (Figure 38). E4 
situated posteriorly of gonopore. Lengths of PI- 
PV: 55, 136, 79, 140, 60. PII with four setae on 
medial side, palp as in male. Lengths of I-leg-4-6: 
242, 252, 378; Lengths of IV-leg-4-6: 369, 340, 272. 
Remarks 
A little known but widespread species, reported 
from the Bismarck Archipelago, Buru and the 
Palau Islands. This record is the first for Australia. 
The female has not been previously described. 
The male resembles in most aspects the 
descriptions of Piersig (1903) and Cook and Bright 
(1983). The specimen of Cook and Bright is smaller 
(body length 1200) and the genital plate is wider 
than my own specimen and that of Piersig. The 
female has three large humps on the anterior body 
part, while the male has only two. Cook and Bright 
suspected that A. matupitensis Piersig was the 
female of A. lohmanni (a female without humps on 
the dorsal shield). Now that male and female have 
been found together, this assumption must be 
rejected. The female of A. lohmanni is close to A. 
tricomutus K. Viets, which has a very similar body 
shape and configuration of the large humps. A. 
tricomutus is smaller, the small humps near the 
eyes are more pointed, the anterior body margin is 
more concave and the genital plate is over its 
whole length of equal width. 
Arrenurus (Brevicaudaturus) tricomutus K. Viets 
Arrenurus tricomutus K. Viets, 1955: 25; K.O. Viets, 
1975: 93; Smit, 1992: 106. 
Material Examined 
Australia: Northern Territory: 4 S, 4 $, Small 
Billabong, Gunlon, Kakadu National Park, 25 July 
1994 (ZMA). 
Remarks 
So far, this species has only been reported from 
Queensland (K. Viets 1955; Smit 1992). Females 
from this study vary in body length from 1548- 
1764 and in body width from 1248-1392, males 
vary in body length from 1248-1399 and in body 
width from 1032-1128. The males are thus smaller 
than specimens from eastern Australia. 
