Gretacarus yorkensis, Smit, Harry, 2016

Smit, Harry, 2016, The water mite genus Gretacarus K. O. Viets, 1978 from Australia (Acari: Hydrachnidia, Mideopsidae: Gretacarinae), with the description of three new species, Zootaxa 4121 (2), pp. 159-166 : 165-166

Gretacarus yorkensis n. sp.

( Figs 4A–E )

Material examined. Holotype male, Jardine River, Cape York Peninsula, Queensland, Australia, 11º 0 9.070 S 142º 21.335 E, alt. 7 m a.s.l., 22-x-2014 (QM).

Diagnosis. Central pair of dorsal glandularia relatively well distanced from each other; gonopore with 2–3 rows of acetabula; hook-like seta of IV-leg-4 moderately bowed.

Description. Idiosoma dorsally 608 long and 494 wide, ventrally 530 long. Dorsal shield 543 long and 413 wide, centre of dorsal shield pinkish, margins yellowish. First coxae not extending to anterior idiosoma margin. Coxal area unmodified, with a ridge extending posteromedially of fourth leg sockets. Gonopore pear-shaped, 82 long, with up to three acetabula in a row; gonopore 82 long. Length of P1-5: 22, 50, 38, 50, 26. P4 stocky, ventral margin with a long tubercle with a truncated seta. Length of I-leg-4–6: 60, 65, 92. Length of IV-leg-4–6: 98, 106, 74. IV-leg-4 with a moderately bowed hook-like seta and four large, bowed setae; IV-leg-5 with five swimming setae.

Female: Unknown.

Etymology. Named after the Cape York Peninsula.

Remarks. The only other Gretacarus species with a more or less similar genital field are G. expansisetus Cook, 1986 , G. novaguinensis Wiles, 1997 and G. tuberipalpis Smit, 1998 . Gretacarus novaguinensis has a different palp, P4 is without a tubercle and the ventral setae of P4 is much more widened anteriorly. Gretacarus tuberipalpis has P4 with a large dorsal extension. However, the new species is most similar to G. expansisetus . The latter species has a modified coxal field, with flap-like extensions of the fourth coxae covering vgl-2 (absent in the new species), the dorsal field has the central pair of glandularia close to each other (much further apart in the new species), the gonopore is somewhat trilobed (pear-shaped in the new species) and has 2-5 rows of acetabula (2-3 in the new species), the large hook-like seta of IV-leg-4 is strongly bowed (less bowed).

Figures

FIGURES 4 A – E. Gretacarus yorkensis n. sp., holotype male. A = dorsum; B = venter; C = genital field; D = palp; E = IV-leg- 4 – 6. Scale bars: A – B = 200 µm, C – E = 50 µm.