Arrenurus (Truncaturus) pinderi, Orginal, 2021

Orginal, Harry Smit, 2021, The water mites of Western Australia (Acari: Hydrachnidia), with the description of 13 new species, Acarologia 61 (4), pp. 928-966 : 959

Arrenurus (Truncaturus) pinderi n. sp.

Zoobank: E7A4E756-5A69-4EB8-9812-C77780EFC84A

( Figure 17 A-D)

Material examined — Holotype male, Three Springs , Tumulus Spring one, Western Australia, Australia, 29°35′29″ S 115°27′94″ E, 28 Sept. 2010, leg. A. Pinder & A. Leung ( WAM) . Paratypes: Two females, Three Springs, Tumulus Spring Thirteen, Western Australia, Australia, 29°35′19″ S 115°26′43″ E, 29 Sept. 2010, leg. A. Pinder & A. Leung ( WAM).

Diagnosis — Male: Cauda indistinctly set off from anterior idiosoma, cauda with a rounded rudimentary hyaline petiole. Female: Genital plates short and narrow, medial margin of Cx-IV as long as medial margin of Cx-III

Description — Male: Idiosoma bluish, dorsally 737 long and 332 wide, ventrally not measurable. Dorsal shield incomplete, 324 wide. Posterior margin of cauda slightly indented, posterolateral margin of cauda more distinctly indented. Cauda with a pair of short setae, near posterior margin a rounded, a rudimentary hyaline petiole ( Figure 17A). Gnathosomal bay U-shaped. Medial margin of Cx-IV larger than medial margin of Cx-III. Gonopore 52 long, genital plates long and narrow, not extending to lateral idiosoma margin ( Figure 17B). Length of P1-5: 28, 66, 44, 76, 39. P2 medially with four setae ( Figure 17C). Length of I-leg-4-6: 114,

126, 110. Length of IV-leg-4-6: 134, 162, 168; IV-leg-4 with a long spur. Third and fourth legs with numerous swimming setae.

Female: Idiosoma colour as in male, dorsally 846 (857) long and 624 (616) wide, ventrally

810 (826) long. Dorsal shield complete, 761 (749) long and 530 (498) wide. Gnathosomal bay U-shaped. Cx-I not reaching to anterior idiosoma margin. Medial margin of Cx-IV as long as medial margin of Cx-III. Medial distance of Cx-IV less than width of one genital valve. Gonopore 122 long, gonopore field with triangular sclerotized patches. Genital plates relatively short and narrow ( Figure 17D). Length of P1-5: 31, 76, 48, 81, 41; palp as in male. Length of I-leg-4-6: 132, 140, 104. Length of IV-leg-4-6: 168, 174, 140. Third and fourth legs with numerous swimming setae.

Etymology — Named after Adrian Pinder, one of the collectors of the material.

Remarks — The shape of the idiosoma, with the cauda indistinctly set off from the anterior idiosoma in combination with a rudimentary hyaline petiole separates the new species from other Arrenurus species. Arrenurus glaucus males occasionally have the cauda not well set off from the anterior idiosoma, but this species has two small, well separated forked setae on the cauda. The female is characterized by its short and narrow genital plates. Occasionally A. glaucus females have narrow genital plates too, but the medial margin of Cx-IV is always longer than the medial margin of Cx-III.