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 perforatus George, 1881 ( Fig. 47 ) Arrenurus sulcator Krendowskij, 1885 Arrenurus forpicatus perforatus Piersig, 1901 Arrenurus madei Koenike, 1909 Material examined: 10 larvae deriving from 3 females . Larvae very large: idiosoma 254–276 µm long. FIGURE 47. Arrenurus perforatus : A—ventral side, B—dorsal plate, C—excretory pore plate, D—pedipalp (scale bars: A, B—100 µm; C, D—20 µm). Dorsum : Dp very large (DpL: 240–268 µm ; DpW: 192–208 µm ), egg-shaped, widest at mid-length. Antero-lateral indents relatively small, obtuse-angled, about 1/6 and 1/4 of plate’s length and width, respectively. DpW/Mp1-Mp1 4.9. Lp2, Mh1 smooth. Mp1-Mp1 intermediate ( 38–45 µm ), shorter than Mp2-Mp2 ( 58–64 µm ); Mp1-Lp2 long ( 48–63 µm ). Venter : Median margins of Cp very long: CpIm 96–102 µm longest, followed by CpIIm ( 61–66 µm ) and CpIIIm ( 30–37 µm ). Their ratio 3:2:1. All setae on Cp bipectinate; V 3 pectinate. C1, C4 loacted far from median margins of Cp. C1-CpIm ( 30–34 µm ) about 3/4 of C4-CpIIIm ( 42– 45 µm ). C1-C2 intermediate ( 42–46 µm ). Expp rhomboid, clearly wider than long. Exp located slightly below plate’s mid-point and below E2. Palps : PIII 1 thick, bipectinate. PV3, PV4, PV5 pectinate. Chelicerae : First segment bent, elongated cylinder-shaped ( 117–118 µm ), slightly narrowing anteriorly. Legs : Somewhat shorter than body; LI= LII = LIII ( Fig. 6 ). ITi8 relatively long; ITi5 bipectinate; IGe3, IIGe3, IIIGe3 thick, bipectinate; IIITa10, IIITa10, IIITa12 relatively large and pectinate. IITi10, IIITi10 located near mid-point of tibia. IIITa8 present.