Rhynchaustrobates uncinatus, Smit & Pešić, 2025

Smit, Harry & Pešić, Vladimir, 2025, New records of hygrobatid water mites from SE Australia (Acari: Hydrachnidia Hygrobatidae) with the description of ten new species, Zootaxa 5566 (3), pp. 481-521 : 519

Rhynchaustrobates uncinatus sp. nov.

Figure 19

Material examined. Holotype male, Dilgry River , Barrington Tops NP , New South Wales, 31°53.639 S 151°31.590 E, 1200 m asl, 10-i-2024 leg. Smit, dissected and slide mounted. ( AMS).

Diagnosis (Female unknown). Anterior margin of the platelet incorporating genital field, Vgl-1 and-2 and excretory pore strongly projecting; ventral margin of P-3 with a long, and comparatively stout, curved projection.

Description. Male. Idiosoma ventrally 459 long, dorsally 419 long and 333 wide. Dorsum soft and lined; postocularia on well-developed platelets ( Figure 19A ), eight pairs of glandularia lying free in the integument; excretory pore terminal. Coxae in three groups, first coxae fused medially ( Figure 19B ); anterior coxae projecting, gnathosomal bay moderately deep and roundly V-shaped, 55 long; a triangular projection forming the roof of the camerostome; distance between tip of Cx-I and posterior margin of Cx-IV 369, Cx-III width 256; Cxgl-4 slightly closer to insertion of fourth leg than to medial suture line of Cx-IV; secondary sclerotization enclosing Vgl-3. Genital field, Vgl-1 and-2 and excretory pore incorporated into platelet which is 153 long and 211 wide, anterior margin of this platelet strongly projecting; genital field with three pairs of acetabula, maximum diameter Ac 1–3: 25, 23–25, 26–27; gonopore narrow, 68 long.

Palp as illustrated in Figure 19D : dorsal length/height: P1, 20/30; P2, 70/57; P3, 58/48; P4, 71/31; P5, 38/12; ventral margin of P3 with a long, thick, curved projection. Gnathosoma 233 long, much longer than high ( Figure 19C ), attached to a long tube of soft integument to produce protrusible gnathosoma. Chelicera 281 long.

Dorsal lengths of I-leg-2–6: 55, 77, 104, 123, 116; dorsal lengths of IV-leg: 139, 71, 138, 131, 147, 142; IV-leg- 3 constricted in anterior half of the segment, IV-leg-5 with two very short swimming setae.

Female: Unknown.

Etymology. Named for the hook-like projection of P-3.

Remarks. Due to the shape of the ventral projection of the male P-3 the new species resembles Rhynchaustrobates tasmanicus Cook, 1986 and R. victorianus Smit, 2015 . Rhynchaustrobates tasmanicus can easily be separated from the new species in the shape of the genital field platelet with the anterior margin nearly straight, medially slightly idented (see Fig. 702 in Cook 1986), excretory pore free on the dorsal side, not incorporated into the genital field platelet and the curved projection on the ventral margin of P-3 comparatively much slender (see Fig. 697 in Cook 1986). Rhynchaustrobates victorianus has a smaller curved projection on the ventral margin of P-3 and the genital field in incorporated in the ventral shield.

Distribution. New South Wales; known only from the type locality.

Figures

FIGURE 19. Rhynchaustrobates uncinatus sp. nov., holotype male, Dilgry River: A—idiosoma, dorsal view; B—idiosoma, ventral view; B—lateral view of gnathosoma, chelicera and palp; D—palp. Scale bars = 100 µm.