Aspidiobates imperfectus, Smit, 2019

Smit, Harry, 2019, The water mite genus Aspidiobates Lundblad, 1941 from Australia (Acari: Hydrachnidia: Hygrobatidae) with the description of two new species, Zootaxa 4550 (1), pp. 115-122 : 117

Aspidiobates imperfectus n. sp.

( Figures 1 A–F)

Material examined. Holotype female, Kauri Creek , Danbulla State Forest, Queensland, Australia, 17°08.056 S 145°35.892 E, alt. 700 m asl, 13-x-2005 ( QM) . Paratype: one male, Whitehead Creek between Bloomfield and Cooktown, Queensland, Australia, 15°46.843 S 145°17.545 E, alt. 184 m asl, 17-x-2014 ( QM) .

Diagnosis. Genital field with four pairs of acetabula on one side, but with aberrant number on the other side. Dorsum of female with one large, unpaired anteromedial plate and two pairs of posterolateral platelets; male with one large, unpaired anteromedial plate and one pair of posterolateral platelets; palp with a large, rounded anteroventral extension in the female, but male without such extension.

Description. Coxal suture lines obliterated. Cx-I extending beyond anterior idiosoma margin. Cxgl-4 extending onto Cx-III. Legs without swimming setae. Female: Idiosoma yellowish, dorsally 636 long and 591 wide, ventrally 721 long. Dorsum with a large, unpaired anteromedial plate with two pairs of glandularia and the postocularia and two pairs of lateral platelets, each with one pair of glandularia. Anteromedial dorsal plate 535 long, anterior lateral dorsal plate 239 long. Genital field with four pairs of acetabula, but in the holotype two acetabula on one side are lacking or obliterated. Gonopore 110 long and 96 wide. Length of P1-5: 24, 102, 76, 130, 40. P2 with a large, rounded anteroventral extension. P4 slender, with two small setal tubercles. Length of I-leg-4- 6: 170, 160, 102. Length of IV-leg-4-6: 200, 198, 120.

Male: Idiosoma dorsally 608 long and 559 wide, ventrally 689 long. Dorsum with one large, unpaired anteromedial plate, 522 long, with three pairs of glandularia and the postocularia, and one pair of posterolateral platelets, each with one gland, 208 long. Genital field with three acetabula on one side and four acetabula on the other, the anterior one small. Gonopore relatively wide, 86 long and 20 wide. Length of P1-5: 24, 94, 80, 126, -. Length of I-leg-4-6: 190, 168, 108. Length of IV-leg-4-6: 226, 234, 164.

Etymology. Named for the imperfect state of the genital field of both the holotype and the paratype.

Remarks. Although some acetabula of the holotype and paratype are lacking, all other characters are not aberrant. Moreover, the lack of one or more acetabula is found also in other Aspidiobates species ( Smit 2001). Most similar to the new species are A. aethes and A. wittenoom Harvey, 1988 , both with four pairs of acetabula. In both sexes of A. aethes dgl-1 and dgl-2 are at equal distance from each other (dgl-1 more distanced than dgl- 2 in the new species) and dgl-1 are closer to the postocularia (more distanced in the new species). Moreover, the excretory pore is located closer to the genital field in A. aethes . The male of A. aethes has two pairs of posterolateral platelets (one pair in the new species). The male of A. wittenoom has P2 with a large anteroventral extension (with a small anteroventral extension in the new species), P4 is more slender in the new species (also in the female) and the genital field is flanked by a pair of glandularia (lacking in the male of A. wittenoom ).

The male of the new species co-occurred with A. neogeometricus n. sp., which has also four pairs of acetabula. However, the palp of the paratype male is similar to palp of the holotype of A. imperfectus , with a rounded anteroventral extension (although smaller than in the female), and is therefore assigned to that species.

Figures

FIGURES 1A–F. Aspidiobates imperfectus n. sp., A–C = holotype female, D–F = paratype male. A = dorsum; B = venter; C = palp; D = dorsum; E = venter; F = palp (P5 lacking). Scale bars: A–B, D–E = 100 µm; C, F = 50 µm.