Arrenurus (Micruracarus) cornuatus, Smit, Harry, 2010

Smit, Harry, 2010, Two new species of the genus Arrenurus from Pohnpei, Federal States of Micronesia (Acari: Hydrachnidia: Arrenuridae), Zootaxa 2606, pp. 50-54 : 51

Arrenurus (Micruracarus) cornuatus n. sp.

( Fig. 1–4 )

Material examined. Holotype male, Nan Pad stream, Pohnpei, Federal States of Micronesia, 1 July 2008 ( ZMAN). Paratypes: three females (one juvenile), same data as holotype ( ZMAN); male, Dolent stream, Pohnpei, Micronesia, alt. 460 m a.s.l., 2 February 2009 ( ZMAN); 3 males, 3 females, Nan Pad stream, Pohnpei, Micronesia, alt. 590 m a.s.l., 30 June 2008 ( BPBM); 1 male, Nan Moatoh stream, Pohnpei, Federal States of Micronesia, 460 m a.s.l., 17 February 2009 ( ZMAN).

Diagnosis. Petiole antler-shaped.

Description. Male: Idiosoma 689 (693–753) long and 454 (446–518) wide. The colour cannot be ascertained as the specimen has been fixed in ethanol. Idiosoma anteriorly indented. Dorsal shield rounded, 381 long and 348 wide. Cauda distinctly sett of from anterior idiosoma, with two lobes separated by a shallow indentation, each lobe with a concavity. Petiole antler-shaped. Anterior coxae pointed, extending beyond anterior idiosoma margin. Genital plate long and narrow, extending to lateral idiosoma margin but not onto dorsum; gonopore 42 long. Lengths of PI-PV: 22, 76, 56, 97, 50; PII medially with two setae in anteroventral corner and two more dorsally located setae. Lengths of I-leg-4–6: 118, 124, 122. Length of IV-leg-4–6: 180, 146, 150; IV-leg-4 without a spur. Third and fourth legs with numerous swimming setae.

Female: Idiosoma 770 (664–770) long and 640 (583–624) wide. Dorsal shield complete, 616 (575–599) long and 502 (470) wide. Idiosoma anteriorly straight to slightly convex, anterior coxae not extending beyond anterior idiosoma margin. Posterolateral corners of idiosoma distinct. Medial margin of third coxae shorter than medial margin of fourth coxae. Medial distance of fourth coxae shorter than width of one genital valve. Gonopore 136 long and 144 wide, genital valves with distinct chitinized patches. Genital field 454 wide, genital plates narrow and sloping, about three times as long as wide. Lengths of PI-PV: 32, 74, 52, 76, 40; palp as in male. Lengths of I-leg-4–6: 134, 140, 120. Lengths of IV-leg-4–6: 138, 170, 156. Third and fourth legs with numerous swimming setae.

Etymology. Named for the antler-shaped petiole.

Remarks. The petiole of the new species is very distinctive and will separate it from all other Arrenurus species. The distinct posterolateral corners of the idiosoma and the shape of the genital field will separate the female from other Arrenurus species.

Figures

FIGURES 1 – 4. Arrenurus cornuatus n. sp. (figures 1 – 3 holotype male, figure 4 paratype female): 1 = dorsal view; 2 = ventral view; 3 = palp; 4 = ventral view. Scale bars: 1 – 2,4 = 200 µm; 3 = 50 µm.