Records of the Western Australian Museum 17 : 447-449 ( 1996 ). 
A new Stygiochiropus from a North West Cape (Western Australia) coastal 
plain cave (Diplopoda: Polydesmida: Paradoxosomatidae) 
William A. Shear 1 and William F. Humphreys 2 
1 Department of Biology, Hampden-Sydney College, Hampden-Sydney, Virginia 23943 U.S.A. 
2 Terrestrial Invertebrate Zoology, Western Australian Museum, Francis Street, Perth, Western Australia 6000 Australia 
Abstract - Stygiochiropus peculiaris sp. nov., is described from Camerons 
Cave, North West Cape, Western Australia. The new species is profoundly 
modified for cave life and its gonopods are more complex than in other 
Stygiochiropus species. 
INTRODUCTION 
Humphreys and Shear (1993) described a new 
paradoxosomatid genus, Stygiochiropus, for three 
new species found in caves in the Cape Range, 
North West Cape, Western Australia. One of these 
species, S. communis, is found in numerous caves 
throughout the karst region, while the other two, 
S. isolatus and S. sympatricus, are known only from 
single caves in the northern part of the generic 
range. 
Camerons Cave (designated C [Cape Range karst 
area]452), from whence comes the new species 
described below, is not located in the Cape Range, 
but on the eastern coastal plain, at an altitude of ca. 
13 m within the Exmouth town site. On the map 
published by Humphreys and Shear (1993; Figure 
1), it would be placed about 4 km east of C-222, the 
type and only locality for S. isolatus. About 13 km 
to the northwest is C-lll, type and only locality for 
S. sympatricus. The nearest cave with S. communis, 
tire most widespread species, is 11 km southwest. 
The cave is shallow and extends through the 
water table. The nature of the limestone in which 
the cave has formed is not known but appears to 
have formed in the Mowbowra Conglomerate, 
which comprises ridges of strongly calcretized 
gravel conglomerate, derived from Pleistocene 
shingle beachface (bar) deposits (Wyrwoll et al. 
1993). The depth of the underlying Tulki limestone, 
within which caves containing the typical Cape 
Range fauna are found, is unknown. 
Biologically, the caves on the coastal plain differ 
from those in the mountains. While some locally 
endemic genera of troglobites are in common, the 
species differ. An undescribed species of Hyella 
(Pseudoscorpionida) and a second species of 
Draculoides (Schizomida), D. bramstokeri Harvey 
and Humphreys, occur in Camerons Cave, along 
with undescribed ctenid and hahniid spiders, and 
a phalangodid opilionid. Draculoides bramstokeri 
also occurs on Barrow Island (Harvey and 
Humphreys 1995), some 160 km to the northeast, 
and several aquatic troglobites have a similar 
distribution (Humphreys 1993); Barrow Island 
would have been connected to the North West 
Cape peninsula about 10,000 years ago at a time of 
low sea level. 
Because of the unique biological significance of 
Camerons Cave, the new milliped species is being 
described to make the name available for 
protection efforts. Camerons Cave is the only 
known humid cave on the eastern coastal plain 
and, save for D. bramstokeri, is the only known 
locality for the several species it contains. 
Stygiochiropus peculiaris sp. nov., is widely 
divergent from its congeners in bearing two 
additional gonopod processes on the femorite, as 
decribed below. This makes it tempting to regard 
the species as the most plesiomorphic of the genus, 
since troglobitic adaptation often leads to gonopod 
simplification, not elaboration (Shear 1972), and the 
closest relatives of the genus have more complex 
gonopods with additional processes. However, S. 
peculiaris is probably as highly adapted to 
troglobitic life as any of the other species, with a 
loose-jointed, elongate body, thin, brittle cuticle, 
and attenuate legs and antennae. The presence of 
this species in a cave formed in Pleistocene 
deposits is intriguing. It seems likely that S. 
peculiaris is older them the cave in which it occurs, 
and as with other Stygiochiropus, lives mainly 
within microcaverns, emerging into caves 
accessible by humans only when conditions are 
propituous (Humphreys and Shear 1993). 
The new species was first noted in 1993 when a 
dead, dried specimen was collected. Subsequently, 
in early 1993, the cave was irrigated and plant Utter 
was added (as described in Humphreys 1991), with 
the result that the fresh specimens described below 
appeared. 
