Arrenurus (Micruracarus) circulodorsalis, Smit, 2021

Smit, Harry, 2021, Water mites from West Africa (Acari: Hydrachnidia), Acarologia 61 (3), pp. 700-746 : 738

Arrenurus (Micruracarus) circulodorsalis n. sp.

Zoobank: 6B1E9954-8274-4089-B1DA-00EFEF6F02AE

( Figure 24 A-D)

Material examined. Holotype male, Lake Dahwenya , Ghana, 5°46.760′ N 0°03.049′ E,

24 m a.s.l., 9 Feb. 2013 ( RMNH). Paratypes: four females (one not sclerotized), same data as holotype ( RMNH). Other material. The Gambia. 0/1/0, pond ± 5 km W of Basse, along road Basse – Bansang, Upper River Division, 12 Feb. 1998.

Diagnosis. Male: Dorsum with a small, rounded dorsal shield, idiosoma posteriorly with a large hollow, posterior idiosoma margin with a closed cleft, gonopore not visible in ventral or posteromedial view. Female: Genital plates extending halfway gonopore field and lateral idiosoma margin and widening laterally.

Description. Male: Idiosoma yellowish, dorsally 648 long and 583 wide, ventrally 624

long. Anterior idiosoma margin straight. Dorsal shield almost circular, 235 long and 251 wide, with the postocularia and Dgl-2. Dgl-1 shifted posteriorly, somewhat posterior to level of Dgl-2 ( Figure 24A ). No petiole present, although the structure illustrated at the posterior margin might suggest this, but this is just an interruption of the idiosoma pores. Idiosoma with a large hollow posteriorly, but this can be examined only in posteromedial view. Gonopore not visible, not in ventral view, nor in posteromedial view. Posterior idiosoma margin straight, with a closed cleft, which widens anteriorly ( Figure 24B ). Length of P1–5: 26, 60, 46, 72, 44. P2 medially with three setae ( Figure 24C ). Length of I-leg-4–6: 101, 114, 132. Length of IV-leg-6: 144, 98, 96.

I- and II-leg-6 with numerous small setae. Legs with many swimming setae.

Female: Idiosoma dorsally 907 (932-948) long and 802 (794-810) wide, ventrally 899

(923-956) long. Dorsal shield complete, 656 (644-680) long and 506 (498-526) wide. Anterior idiosoma margin straight, posterolateral corners of idiosoma absent. Anterior coxae extending to or just beyond anterior idiosoma margin. Medial margin of Cx-IV longer than medial margin of Cx-III. Medial distance of Cx-IV longer than width of one genital valve. Gonopore field 166 wide and without sclerotized patches, gonopore 105 long. Genital field 567 wide, genital plates widening laterally, extending halfway gonopore field and lateral idiosoma margin ( Figure 24D ). Excretory pore lying halfway gonopore field and posterior idiosoma margin. Length of P1–5: 32, 72, 58, 80, 50. P3 medially with one seta. Length of I-leg-4–6: 110, 124, 122. I- and II-leg-6 with less small setae compared to male. Length of IV-leg-4–6: 170, 162, 136. Legs with many swimming setae.

Etymology. Named for the rounded dorsal shield of the male.

Remarks. The male is well characterized by its rounded dorsal shield, the absence of a petiole and the gonopore not visible in ventral or posteromedial view. No other Afrotropical Arrenurus species shares this combination of characters. The female is well characterized by the shape of the genital plates.

Figures

Figure 24 Arrenurus (Micruracarus) circulodorsalis n. sp., holotype male A-C, paratype female D. A – dorsum; B – venter; C – palp; D – venter. Scale bars: A-B, D = 200 µm, C = 50 µm.