Arrenurus DugŁs, 1834

Smit, H., 2011, New Species Of Water Mites From New Guinea (Acari: Hydrachnidia, Halacaridae), Acarologia 51 (3), pp. 321-345 : 341-344

Genus Arrenurus DugŁs, 1834

The water mite genus Arrenurus is the most speciesrich genus of all water mites, with some 950 species known worldwide. Thus far, only seven Arrenurus species have been described from New Guinea ( Daday 1901; Wiles 1997b).

Arrenurus (Arrenurus) basegensis n. sp. ( Figure 15–16 )

Material examined — Holotype male, Pandanus marsh Base G beach, Jayapura, Papua province, New Guinea, Indonesia, 2°31.445’ S; 140°44.503’ E, 30-iii-2010. Paratypes: fore females, same data as holotype .

Diagnosis — Male with a scissor-shaped petiole with a pair of stout setae near its base; hyaline membrane broad. Female with the idiosoma truncated posteriorly and narrow genital plates.

Description — Male: Idiosoma bluish, 849 long (including petiole), 656 long till tip of pygal lobes; width of idiosoma 551. Anterior margin of idiosoma slightly concave. Dorsal shield incomplete, 356 long. D4 on a hump with hyaline tip, distanced from each other. Cauda short, pygal lobes distinct ( Figure 15a ). Hyaline membrane broad, laterally bluntly pointed. Petiole long, scissor-shaped, with a pair of stout setae near its base, anterior part split in two; in lateral view posteriorly slightly upturned ( Figure 15b ). Genital plates long and bowed, extending to lateral idiosoma margin, visible in dorsal view ( Figure 15c ). Lengths of PI-PV: 26, 56, 52, 64, 37; PII medially with four setae ( Figure 15d ). Lengths of I-leg-4-6: 110, 90, 84; dorsal and ventral margin of I-leg-6 (and also II-leg-6) with numerous fine, long setae. Lengths of IV-leg-4-6: 184, 72, 104; IV-leg-4 without spur, but with an anterior triangular extension. Third and fourth legs with numerous swimming setae.

Female: Idiosoma 1053 (915 – 992) long and 900 (782 – 867) wide, very dark brown. Anterior margin of idiosoma almost straight, posteriorly truncated. Dorsal shield complete, 672 long and 510 wide. First coxal plates not extending to anterior idiosoma margin. Medial margin of third coxal plates larger than medial margin of fourth coxal plates. Medial distance of third + fourth coxal plates about 1.5 times width of gonopore valve. Genital plates long and very narrow ( Figure 16 ). Gonopore with large sclerotized patches, covering gonopore almost completely. Lengths of PI-PV: 36, 80, 51, 104, 53; PII medially with two slender setae and more near dorsal margin one stout seta. Lengths of I-leg-4-6: 144, 148, 130. Lengths of IV-leg-4-6: 178, 162, 138. Second, third and fourth legs with numerous swimming setae.

Etymology — Named after the type locality, Base G beach near Jayapura.

Remarks — In the collection from the type locality two types of females are present. The larger females have the gonopore with large sclerotized patches, a phenomenon very frequently found in the subgenus Arrenurus . They are therefore assigned to the new species. The smaller females have the gonopore without sclerotized patches. The new species is well characterized by the shape of the petiole. Some Oriental Arrenurus species , i.e. A. kurtvietsi Lundblad,1969 , A. liberatus Walter, 1929 and A. confinis Lundblad, 1969 also have the base of the petiole with two stout setae, but the shape of the petiole is very different from the new species.

Arrenurus (Micruracarus) foiorum Wiles, 1997 ( Figure 17 )

Material examined — Holotype: male, Lake Kutubu near R.[iver] Sorrel, 10-vii-1988 , Papua New Guinea, leg. P. R. Wiles (slide A197, BMNH); paratype: same location (slide A197, BMNH) [Slide A 197 labelled Arrenurus foii and Holotype, but two males present. The male with the palp not detached and with the dorsum visible in the slide is considered by me as the holotype, the other male therefore considered a paratype]. Other material. 2/0/0, Pandanus marsh Base G beach, Jayapura, Papua province , New Guinea, Indonesia, 2°31.445’ S; 140°44.503’ E, 30-iii-2010 .

Remarks — Reported previously from Papua New Guinea by Wiles (1997b). The male have a peculiar structure on the dorsum ( Figure 17 ), which is somewhat variable in shape.

Figures

FIGURE 15: Arrenurus basegensis n. sp., holotype male: a – dorsal view. Scale bar = 200 µm; b – lateral view petiole. Scale bar = 50 µm; c – ventral view. Scale bar = 200 µm; d – palp. Scale bar = 50 µm.

FIGURE 16: Arrenurus basegensis n. sp., paratype female: ventral view. Scale bar = 200 µm.

FIGURE 17: Arrenurus foiorum Wiles, male: detail of dorsum. Scale bar = 50 µm.