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 claviger Koenike, 1885 ( Fig. 16 ) Arrenurus calycularis Georgevitsch, 1906 Material examined: 10 larvae deriving from 10 females . Larvae large: idiosoma 234–260 µm long. Dorsum : Dp relatively large (DpL: 220–244 µm ; DpW: 174–184 µm ), ellipsoid shield-shaped. Antero-lateral indents relatively shallow, obtuse-angled, about 1/5 of dorsal plate’s length and width. DpW/Mp1-Mp1 2.3. Lp2, Mh1 bipectinate. Mp1-Mp1 very long ( 77–78 µm ), longer than Mp2-Mp2 ( 62–64 µm ); Mp1-Lp2 intermediate ( 39–49 µm ). Venter : CpIm ( 70–74 µm ) about 1.5 times longer than CpIIm ( 42–46 µm ), which in turn are slightly longer than CpIIIm ( 38–41 µm ); their ratio 1.5:1.1:1. C1, C2, C3, V 3 bipectinate; C4, Lh2, Lh3 pectinate; other setae smooth. C4-CpIIIm ( 31–33 µm ) 1.5 times that of C1-CpIm ( 20–22 µm ). C1-C2 very long ( 49–58 µm ). Expp pentagonal, its length and width equal. Exp situated above plate’s mid-point and above E2. Palps : PIII 1 bipectinate; PIV1 relatively thin. Chelicerae : First segment bottle-shaped ( 89–94 µm ), one side flat, other convex. Legs : Shorter than body; LI< LII < LIII ( Fig. 3 ). ITi8 thin, long; IITi10 long, pectinate, situated at 1/3 distance from distal end of tibia; IIITi10 situated close to mid-point of tibia. Hosts : Ischnura elegans ( Davids 1997 ; Zawal & Dyatlova 2006).