Procorticacarus australicus ( K.O. Viets, 1978 )

Smit, Harry, 2015, The water mite genus Procorticacarus K. O. Viets in Australasia (Acari: Hydrachnidia, Hygrobatidae), Zootaxa 3956 (1) : -

Procorticacarus australicus ( K.O. Viets, 1978)

( Figs. 1A–C )

Material examined. Type material: Holotype female, East branch of Barwon River, outflow from Lake Elisabeth, Victoria, Australia, 9-iii-1075, leg. I. Aldenhoven ( SMF), paratype female, same data as holotype ( SMF). Other material. New South Wales. 0/2/0, Unnamed creek near Carruthers Creek, Mt Kosciuszko NP, 36º 24.621 S 148º 18.338 E, alt. 1931 m a.s.l., 6-xii-2003. Queensland. 0/1/0, Dalrymple Creek, Goomburra Forest Reserve, 27º 58.781 S 152º 20.621 E, 5-xi-2005; 2/1/0, Charmillin Creek, Tully Falls NP, 17º 41.968 S 145º 31.423 E, alt. 794 m a.s.l., 6-xi-2014.

Description. Male: (in parenthesis measurements of the second male) Idiosoma dorsally 389 (389) long and 340 (348) wide, ventrally 437 (429) long. Idiosoma with numerous hair-like papillae, arranged in a reticulate pattern, especially on the anteromedial dorsal plate. Dorsum with a large anteromedial plate, 267 (251) long and 247 (251) wide, this plate with a pair of postocularia. Posterior to the anteromedial plate three pairs of glandularia on small platelets, the most anterior pair much further apart than other two pairs (one glandularium on dorsum lacking). First coxae fused medially, third and fourth coxae separated medially. Cxgl–4 located near middle of fourth coxae, the latter papillate near posterior margin. Genital plate with three pairs of acetabula, widely separated from each other. Gonopore 28 long, pregenital sclerite with a row of eight small setae. Glands of Vgl–2 absent, only the setae present. Length of P1–P5: 18, 54, 92, 100, 36; P2 with a large ventral extension, P3 and P4 slender; P4 without a ventral hyaline margin. Length of I-leg-4–6: 84, 90, 72. Length of IV-leg-4–6: 134, 132, 106. Legs without swimming setae.

Remarks. According to K.O. Viets (1978) the female of P. australicus differs from the female of P. hirsutus in a more slender palp, with P4 with a ventral hyaline margin with an angular corner proximal of the peg-like seta (angular corner absent in P. hirsutus ). Moreover, the ratio of P-3/P-4 is with 0.855–0.890 larger in P. australicus than hirsutus (ratio of 0.803–0.805). Cook (1986) used in his key the location of the peg-like seta of P4, decidedly proximal in australicus and more or less near the middle in hirsutus . However, in the holotype this character is clear, but in the paratype female it is less clear, distances are proximal 46 % versus 54 % distal (projected on the dorsal margin). Cook (1986) used the medial projection of the fourth coxae, which is well posterior to the suture lines between the third and fourth coxae in hirsutus , and slightly anterior to the suture lines between the third and fourth coxae in australicus . However, in the male of this study there is clear angular corner of the fourth coxae. Another useful character not mentioned by K.O. Viets nor Cook is the location of the postocularia in the female. These are located anterior to the middle of the anteromedial plate in P. australicus and posterior to the middle in P. hirsutus . The male was unknown thus far, and is here described for the first time. It is very similar to P. hirsutus , but the anteromedial plates occupies a larger part of the dorsum, and P3 and P4 are more slender (ratio P3/P4 0.92).

Figures

FIGURE 1. A – C. Procorticacarus australicus (K. O. Viets), male: A = dorsum; B = venter; C = palp. Scale bars = 50 µm.