Morphological characteristics of water mite larvae of the genus Arrenurus Dugès, 1834, with notes on the phylogeny of the genus and an identification key Author Zawal, Andrzej text Zootaxa 2008 2008-05-07 1765 1 1 75 https://biotaxa.org/Zootaxa/article/view/zootaxa.1765.1.1 journal article 10.11646/zootaxa.1765.1.1 1175­5334 5123752 Arrenurus pustulator (O. F. Müller, 1776) ( Fig. 20 ) Hydrachna pustulator O. F. Müller, 1776 Trombidium pustulator Fabricius, 1793 Atax pustulator Fabricius, 1805 Material examined: 10 larvae deriving from 1 female . Larvae medium-sized: idiosoma 183–206 µm long. Dorsum : Dp medium-sized (DpL: 176–198 µm ; DpW: 150–161 µm ), oval, anterior and posterior margins rounded. Antero-lateral indents relatively large, about 1/4 of plate’s width and length, obtuse-angled. DpW/ Mp1-Mp1 3.1. Lp2, Mh1 smooth and thin. Mp1-Mp1 intermediate length ( 47–49 µm ), slightly longer than Mp2-Mp2 ( 39–43 µm ); Mp1-Lp2 relatively short ( 36–41 µm ). Venter : CpIIIm ( 24–28 µm ) slightly longer than CpIIm ( 23–25 µm ), CpIm ( 62–66 µm ) almost three times as long. CpI:CpII:CpIII ratio 2.7:1:1.1. Setae on Cp smooth. C1, C4 located close to median margins of Cp. C1-CpIm ( 15–16 µm ) longer than 2/3 of C4- CpIIIm ( 22–24 µm ); C1-C2 intermediate ( 42–46 µm ). Expp pentagonal, distinctly wider than long. Exp located below plate’s mid-point and below E2. Palps : PV6 relatively thick; PV3, PV4, PV5 thin. Chelicerae : Relatively large, thick ( 82–85 µm ) first segment. Legs : Shorter then body; LI< LII = LIII ( Fig. 4 ). IIITa8 present. ITr1, IITr1, IIITr1, IFe7, IIFe7, IIIFe7 pectinate. IITi10, IIITi10 pectinate, relatively long, situated close to distal ends of tibia; IIITa13 pectinate; IIITa11, IIITa12 pectinate, large. Hosts : Coenagrion hastulatum , Cordulia aenea (L.) ( Davids 1997 ).