Arrenurus (Megaluracarus) dilatacaudatus, Smit, 2017

Smit, Harry, 2017, New records of water mites from standing waters in Thailand, with the description of nine new species (Acari: Hydrachnidia), Zootaxa 4312 (1), pp. 69-91 : 87-88

Arrenurus (Megaluracarus) dilatacaudatus n. sp.

( Fig. 10 )

Material examined. Holotype male, Phan Reservoir, Udon Thani Province, Thailand, 17° 50.052ʹ N 103° 04.356 ʹ E, 31-i-2011 ( RMNH).

Diagnosis. Cauda widening posteriorly, with a medial cleft.

Description. Male: Idiosoma green, 697 dorsally long and 393 wide. Anterior idiosoma margin concave. Tips of first and second coxae pointed, extending beyond anterior idiosoma margin. Dorsal shield complete, circular, with two pairs of glandularia and the postocularia, 259 long and 267 wide. Cauda 239 wide, widening posteriorly, posterior margin with a median cleft. Gonopore 28 long. Palps typical, length of P1-5: 24, 56, 46, 58, 34. Length of I-leg-4–6: 108, 99, 110 (to tip). Length of IV-leg-4–6: 198, 99, 104 (to tip). IV-leg-4 without a spur. Third and fourth legs with numerous swimming setae.

Female: Unknown.

Etymology. Named for the widening (tapering anteriorly) cauda.

Remarks. Four Arrenurus species from the Oriental and Australasian regions have similar cauda with a median cleft but they do not broaden posteriorly. Arrenurus dahli Piersig, 1898 from the Bismarck Archipelago has the cauda widest in the middle, while the dorsal shield is elongate. Arrenurus duffelsi Smit, 1996 from Sulawesi has a wider cleft, the dorsal shield is larger and more rectangular and the genital plates are more narrow. The third species is A. santaniensis Wiles, 1997 from New Guinea. This species has a very narrow cleft, and the cauda is not widening posteriorly. The last species is A. aliensis Wiles, 1993 , but like in the previous species but the cauda is widest in the middle.

Figures

FIGURE 10. Arrenurus dilatacaudatus n. sp., holotype male. A = dorsum; B = venter; C = palp. Scale bars = 50 µm.