Arrenurus tetracyphus (O. F. Müller, 1776)

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 : 37

Arrenurus tetracyphus (O. F. Müller, 1776)

( Fig. 21 )

Material examined: 10 larvae deriving from 10 females.

Larvae relatively large: idiosoma 214–260 µm long.

Dorsum: Dp relatively large (DpL: 204–228 µm; DpW: 152–176 µm), egg-like and shield-shaped, widest in mid-length, with relatively large, obtuse-angled antero-lateral indents about 1/5 and 1/4 of dorsal plate’s length and width, respectively. DpW/Mp1-Mp1 3.1. Lp2, Mh1 pectinate, thicker than remaining setae. Mp1- Mp1 intermediate length (48–56 µm), equal to Mp2-Mp2 (52–56 µm); Mp1-Lp2 relatively short (34–43 µm). Venter: Median margins of CpII very short (29–34 µm), compared to those of CpIII (40–46 µm) and CpI (70– 75 µm). CpI:CpII:CpIII ratio 2.5:1:1.5. C2, C3, C4 bipectinate, C1 smooth. V 3 bipectinate; Lh2, Lh3 pectinate. C1-CpIm (20–23 µm) more than 2/3 of C4-CpIIIm (34–38 µm); C1-C2 intermediate (42–44 µm). Expp pentagonal, clearly wider than long. Exp located slightly above plate’s mid-point, above E2. Palps: PIII 1 thick, bipectinate; PV6 short, thick. Chelicerae: First segment shaped like a curved cylinder, slightly tapered anteriorly (67–70 µm). Legs: Somewhat shorter than body; LI< LII = LIII ( Fig. 4 ). ITi8 thin, long, pectinate; ITa13, IITa13, IITi10 long, pectinate. ITa12, IITa12, IIITa11, IIITa12, IIITa7, IIITa9, IIITa10 pectinate. IIITa14 only slightly closer to proximal end of tarsus than IIITa13 or at same level.

Figures

FIGURE 4. Diagram of proportions of leg (LI<LII=LIII) and body length.

FIGURE 21. Arrenurus tetracyphus: A—ventral side, B—dorsal plate, C—excretory pore plate, D—leg III (scale bars: A, B—100 µm; C—20 µm; D—50 µm).