Arrenurus tricuspidator (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 : 27-28

Arrenurus tricuspidator (O. F. Müller, 1776)

( Fig. 14 )

Hydrachna tricuspidator O. F. Müller, 1776

Arrenurus maximus Piersig, 1894

Material examined: 10 larvae deriving from 10 females.

Larvae relatively large: idiosoma 224–260 µm long.

Dorsum: Dp an ellipsoid shield, posterior margin sharpened; size varies widely (DpL: 210–250 µm; DpW: 164–188 µm). Antero-lateral indents obtuse-angled, small (about 1/6 and 1/4 of dorsal plate’s length and width, respectively). DpW/Mp1-Mp1 2.4. Lp2, Mh1 bipectinate ( Fig. 2 ). Mp1-Mp1 very long (71–76 µm), much longer than Mp2-Mp2 (56–59 µm); Mp1-Lp2 intermediate (40–46 µm). Venter: CpIm longest (62–68 µm), CpIIm (38–43 µm), CpIIIm (28–32 µm), their length at a ratio of 2:1.3:1. All setae on Cp as well as V 3 pectinate; Lh2, Lh3 pectinate. C2, C3, C4, V 3 clearly thicker than other setae. C1-CpIm (16–20 µm) about 3/ 5 of C4-CpIIIm (28–33 µm). C1-C2 long (47–54 µm). Expp pentagonal, somewhat wider than long. Exp in sub-central position on plate, slightly above E2. Palps: PIII 1 bipectinate; PIV1 relatively thin. Legs: Shorter than body; LI< LII = LIII ( Fig. 4 ). IITi10, IIITi10 pectinate, located near mid-point of tibia; ITi8 long. Hosts: Lestes sponsa , Coenagrion pulchellum , Cercyon lindenii (Sél.) , Erythromma najas , Enallagma cyathigerum , Ischnura elegans , Platycnemis latipes (Ram.) , P. pennipes (Pall.) ( Davids 1997; Baker et al. 2006; Baker et al. 2007).

Figures

FIGURE 2. Diagram of pedipalp chaetotaxy and solenidiotaxy of larva of Arrenurus genus: —solenidium, — smooth seta, —pectinate seta, —bipectinate seta, —thin seta, —medium-thickness seta, — thick seta,

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

FIGURE 14. Arrenurus tricuspidator: A—ventral side, B—dorsal plate, C—excretory pore plate, D—pedipalp, D —leg I (scale bars: A, B—100 µm; C—50 µm; D—20 µm).