Australian Arrenurus 
247 
Figures 45-46 Arrenurus (Megaluracarus) vanderpalae 
200 pm. 
nymph, same data as holotype (NTM); 1 6, 
Billabong Yellow Waters, Kakadu National Park, 
21 July 1994 (ZMA); 1 i, 1 $, Jim Jim Billabong at 
crossing with Kakadu Highway, Kakadu National 
Park, 22 July 1994 (ZMA). 
Other Material 
Australia: Western Australia: 1 6, Pond 
Hancock Gorge, Hamersley Range National Park, 
14 August 1994 (WAM); 1 6,9 9, Pond Snake 
Creek, Millstream-Chichester National Park, 17 
August 1994 (WAM); 1 6,1 9, Jones River, east of 
Roeburne, 17 August 1994 (ZMA). 
Diagnosis 
Posterior body margin of male with a cleft, which 
widens anteriorly; petiole hyaline, tong-shaped; 
genital plates very narrow, extending onto dorsum. 
Female with large chitinous patches on genital 
valves, the anterior patches smaller than the 
posterior, anterior margin of posterior patch 
straight; genital plates long, sloping posteriorly and 
widened laterally. 
Description 
Male 
Body 802 (703-786) long and 718 (592-674) wide. 
Body colour blue. Anterior body margin concave. 
Cauda present, caudal lobes rounded. Posterior 
body margin with a cleft, which widens anteriorly. 
Dorsal furrow complete; dorsal shield 422 (359- 
388) long, posterior margin undulating. D1 on 
humps. Gonopore 48 long. Genital plates long and 
narrow, extending onto dorsum (Figure 47). Petiole 
present, hyaline, tong-shaped (Figure 48). Lengths 
of PI-PV: 29, 53, 38, 84, 43. PII rectangular, with 
four setae on medial side, PIV with a large, 
rounded anteroventral comer (Figure 49). Lengths 
of I-leg-4-6: 112, 116, 136. Lengths of IV-leg-4-6: 
170, 146, 116; IV-leg-4 without spur. 
Female 
Body 912 (776-941) long and 795 (669-805) wide. 
Anterior body margin slightly concave. 
Posterolateral comers of body indistinct. Posterior 
body margin concave, straight or slightly convex. 
Dorsal furrow complete, dorsal shield 718 (572- 
708) long. D1 on small humps. Medial margin of 
CX4 larger than medial margin of CX3. Medial 
distance of CX4 as large as or smaller than width 
of genital valve. Gonopore 87 long. Genital valves 
with large chitinous patches, the anterior smaller 
than the posterior. Anterior margin of posterior 
patches straight. Genital plates long, sloping 
