Arrenurus mediorotundatus Thor, 1898

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 : 47

Arrenurus mediorotundatus Thor, 1898

( Fig. 30 )

Arrenurus halberti Piersig, 1900

Arrenurus curvisetus Viets, 1936

Material examined: 10 larvae deriving from 10 females.

Larvae large: idiosoma 258–264 µm long.

Dorsum: Dp large (DpL: 252–258 µm; DpW: 206–216 µm), egg-shaped, widest at mid-length. Antero-lateral indents relatively small, obtuse-angled, about 1/5 and 1/4 of plate’s length and width, respectively. DpW/ Mp1-Mp1 4.1. Lp2, Mh1 smooth. Mp1-Mp1 relatively long (50–53 µm), shorter than Mp2-Mp2 (56–58 µm); Mp1-Lp2 relatively long (40–46 µm). Venter: CpIm (78–82 µm) and CpIIIm (50–54 µm) very long; CpIIm intermediate length (32–34 µm); CpI:CpII:CpIII ratio 2:1:1.5. All setae on idiosoma smooth. C1-CpIm (22– 24 µm) about 6/7 of C4-CpIIIm (26–28 µm). C1-C2 relatively long (49–50 µm). Expp triangular in outline, sides clearly rounded, somewhat wider than long; distinct process on upper margin. Exp located below plate’s mid-point, about level with E2. E1 located far from Expp anterior margin. Palps: PIII 1 bipectinate; PV6 thick. Chelicerae: First segment (76–81 µm) cylindrical, with one margin slightly concave, other convex; margins tend to converge anteriorly. Legs: Shorter than body; LI< LII < LIII ( Fig. 3 ). ITi7 thick; ITi8 thin, short; IITi8 relatively thin, bipectinate; IITi10, IIITi10 located close to mid-length of tibia.

Figures

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

FIGURE 30. Arrenurus mediorotundatus: A—ventral side, B—dorsal plate, C—excretory pore plate (scale bars: A, B— 100 µm; C—20 µm).