Arrenurus stjoerdalensis Thor, 1899

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 : 49-50

Arrenurus stjoerdalensis Thor, 1899

( Fig. 32 )

Arrenurus finmarchicus Thor, 1922 Material examined: 10 larvae deriving from 10 females.

Larvae intermediate length: idiosoma 188–203 µm long.

Dorsum: Dp relatively small (DpL: 188–191 µm; DpW: 149–155 µm), egg-shaped, widest in mid-length; posterior margin sharpened. Antero-lateral indents relatively small, strongly obtuse-angled, about 1/6 and 1/3 of plate’s length and width, respectively. DpW/Mp1-Mp1 4.3. Lp2, Mh1 smooth. Mp1-Mp1 relatively short (33–37 µm), shorter than Mp2-Mp2 (42–45 µm); Mp1-Lp2 relatively short (36–38 µm). Venter: CpIIm short (24–27 µm); CpIIIm (38–45 µm), CpIm (69–70 µm) intermediate length. CpIm: CpIIm: CpIIIm ratio 2.7:1:1.6. C1, C4 bipectinate; remaining setae smooth. C1-CpIm (23–26 µm) about 6/7 of C4-CpIIIm (26–29 µm). C1-C2 relatively short (36–39 µm). Expp triangular, much wider than long. Exp located distinctly below mid-point of plate, slightly above E2 which are located very low on plate. Palps: PIII 1 bipectinate; PIV1 relatively thin. Chelicerae: First segment elongated (76–85 µm) and curved, its margins converging anteriorly. Legs: As long as body; LI< LII = LIII ( Fig. 4 ). ITi7 thick; ITi8 long; IITi10, IIITi10 smooth, located in middle of tibia; IIITa12 pectinate.

Figures

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

FIGURE 32. Arrenurus stjoerdalensis: A—ventral side, B – dorsal plate, C – excretory pore plate, D – leg III (scale bars: A, B—100 µm; C, D—20 µm).