Arrenurus biscissus Lebert, 1879

Zawal, Andrzej, 2008, Morphological characteristics of water mite larvae of the genus Arrenurus Dugès, 1834, with notes on the phylogeny of the genus and an identification key, Zootaxa 1765 (1), pp. 1-75 : 59-60

Arrenurus biscissus Lebert, 1879

( Fig. 42 )

Arrenurus sinuator f. biscissa Lebert, 1879

Arrenurus fissus Viets, 1908

Material examined: 10 larvae deriving from 3 females.

Larvae large: idiosoma 258–282 µm long.

Dorsum: Dp egg-shaped (DpL: 240–280 µm; DpW: 220–244 µm), widest at mid-length. Antero-lateral

indents very small, barely visible, strongly obtuse-angled, 1/5 and 1/7 of plate’s width and length, respectively. DpW/Mp1-Mp1 5.2. Lp2, Mh1 smooth. Mp1-Mp1 intermediate (43–44 µm), much smaller than Mp2- Mp2 (68–70 µm); Mp1-Lp2 intermediate (38–46 µm). Venter: CpIm (94–106 µm) clearly longest, CpIIm (57– 58 µm), CpIIIm (24– 26 µm), their ratio 3.9:2.3:1. All Cp setae bipectinate. C1-CpIm (28–29 µm) about 3/4 of C4-CpIIIm (41–46 µm). C1-C2 long (57–62 µm). Expp pentagonal, with characteristic process in lower part, base of process surrounding Exp. Exp located distinctly below plate’s mid-point and below E2. Palps: PIII 1 thick, bipectinate; PV4, PV5 bipectinate; PV5 thicker and shorter than PV4. Chelicerae: First segment shaped like a long cylinder (100–110 µm), slightly bent at distal end, margins parallel. Legs: Long, longer than body; LI< LII < LIII ( Fig. 3 ). IGe3, ITi3, IIGe3, IIGe4, IITi3, IIIGe3, IIIGe4, IIITi3, IIITi4 relatively thick and bipectinate. ITi8 long, thin; IITi10, IIITi10 pectinate, located close to mid-point of tibia.

Figures

FIGURE 3. Diagram of proportions of leg (LI<LII<LIII) and body length.

FIGURE 42. Arrenurus biscissus: A—ventral side, B—dorsal plate, C—excretory pore plate, D—pedipalp (scale bars: A, B—100 µm; C, D—20 µm).