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 bruzelii Koenike, 1885 ( Fig. 15 ) Arrenurus emarginator Bruzelius, 1854 Material examined: 10 larvae deriving from 10 females . Larvae of medium size: idiosoma 212–228 µm long. Dorsum : Dp medium sized (DpL: 202–214 µm ; DpW: 146–158 µm ), typically shield-shaped. Antero-lateral indents relatively deep, slightly obtuse-angled, about 1/5 and slightly more than 1/4 of dorsal plate’s length and width, respectively. DpW/Mp1-Mp1 3.1. Lp2 and Mh1 thicker than other setae, bipectinate. Mp1- Mp1 ( 46–50 µm ) equal to Mp2-Mp2 ( 46–50 µm ); Mp1-Lp2 small ( 36–38 µm ). Venter : CpIm, CpIIm, CpIIIm 78–80, 34–37, 44– 46 µm long, respectively, their ratio being 2.3:1:1.3. All Cp setae and V 3 bipectinate; Lh1, Lh2, Lh3 pectinate; V 1, V 2, V 4 smooth. C1-CpIm ( 20-22 µm ) about 2/3 of C4-CpIIIm ( 30–35 µm ). C1-C2 long ( 47–54 µm ). Expp rhomboid, wider than long (length to width ratio 1:1.3). Exp situated sub-centrally on plate, slightly above E2. Palps : PIII 1 bipectinate; PIV1 relatively small. Chelicerae : First segment elongated ( 94–98 µm ), margins slightly curved, converging anteriorly. Legs : Longer than body; LI= LII < LIII ( Fig. 6 ). All tarsi distinctly tapered posteriorly. Almost all leg setae pectinate; ITi8 thick, of intermediate length; ITi7, IITi7, IITi8, IIITi7, IIITi8 of intermediate length, but longer than in other species. IITi10, IIITi10 pectinate, situated near mid-length of tibia. IIITa8 present; IITa14 and IIITa14 seta closer to distal end than IITa13 and IIITa13, respectively. Hosts : Coenagrion hastulatum , C. puella , C. pulchellum , Cercyon lindenii , Erythromma najas , Enallagma cyathigerum , Ischnura elegans ( Davids 1997 ; Baker et al. 2006 ).