Australiobates papillatus, 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 : 491-496

Australiobates papillatus sp. nov.

Figures 5–8

Material examined. Holotype male, New South Wales, unnamed creek at crossing with Dome Road , Dorrigo NP , 30°15.966 S 152°57.042 E, 137 m asl, 8-xi-2003 leg. Smit, dissected and slide mounted ( AMS). Paratypes: 1[palp lost]/2/0, unnamed creek at crossing with Wyndham-Candelo Road , 11-xii-2003 leg. Smit, 0/1/0 dissected and slide mounted ( RMNH) .

Other material. New South Wales. 2 (juvenile specimens)/1 (juvenile specimen)/0, Mumbulla Creek at Mumbulla Creek Picnic Area , Biamanga NP , 36°34’32.92” S 149°53’37.93” E. 12-xii-2003, 1/1/0 dissected and slide mounted .

Diagnosis. Integument papillate; coxae with sexual dimorphism (in male coxal field merged to a unique ventral plate, including Vgl-1, -2, and -3, genital field and excretory pore; in female coxal plates, Vgl-1, -2, and -3, genital field and excretory pore separate); palpal segment comparatively long, P3 distinctly bulging in posterior half of the segment, ventral margin of P4 with two short, thin setae, placed relatively close to each other.

Description. Male (holotype). Idiosoma dorsally 778 and 669 wide, ventrally 831 long. Integument with papillae as presented in Figure 5A (inset). Ventral sclerites incorporated into secondary sclerotization to form a complete ventral shield ( Figure 5B ) and continues onto the periphery of the dorsum ( Figure 5A ). Cx-III width 488; posterior apodemes of Cx-IV short. Genital field 146 wide between outer edges of genital acetabula, three pairs of acetabula in a curved line ( Figure 5B : inset), maximum diameter Ac 1–3: 43, 31, 38; gonopore 106 long. Ejaculatory complex 228 long.

Palp as illustrated in Figures 5C–D : dorsal length/height: P1, 34/33; P2, 92/57; P3, 123/55; P4, 155/28; P5, 47/16; palpal segment comparatively long, ventral margin of P2 nearly straight, P3 without setae, distinctly bulging in posterior half of the segment, ventral margin of P4 with two short, thin setae, placed relatively close to each other and extend distally at a sharp angle. Gnathosoma with its long posterior process 316 long. Chelicera 246 long.

Dorsal lengths of I-leg: 62, 103, 163, 197, 198, 218; terminal segments of I-leg comparatively long and slender ( Figure 5E ); these segment as in female ( Figure 6B ), except there are two longer setae on I-leg- 6 in the male; dorsal lengths of IV-leg: 109, 138, 203, 241, 269, 259; III-leg-5 with two swimming setae, IV-leg-5 with two long swimming setae.

Female (paratype). Idiosoma ventrally 1244 long and 1069 wide. Coxal plates separated but with an extended border of secondary sclerotization, coxal field 581 long, Cx-III width 638. Genital field 228 long and 269 wide; genital plates 134–147 long, pregenital sclerite 120 wide, maximum diameter Ac 1–3: 29–47, 38–46, 34; gonopore 188 long; eggs (n = 4) maximum diameter 142–147.

Palp: dorsal length/height: P1, 45/41; P2, 117/77; P3, 177/73; P4, 197/37; P5, 55/17. Gnathosoma with its long posterior process 369 long.

Dorsal lengths of I-leg: 75, 147, 209, 272, 272, 261; dorsal lengths of IV-leg: 153, 181, 259, 347, 369, 343; number of swimming setae on IV-leg as in male.

Etymology. Named for its papillate integument.

Remarks. Presence of a papillate integument and a characteristic shape of the palp (palpal segment comparatively long, especially P3, which bulging in its posterior half, and P-4 with two relatively short and thin setae, placed close to each other) separate the new species from all other members of the genus Australiobates .

The fusion of the ventral sclerites into a ventral sclerites in the males makes the new species similar to A. ventriscutatus Cook, 1986 , a species which can be easily separated in the shape of the palp (palpal segment relatively stocky, ventral setae on P-4 relatively long, see figure 478 in Cook 1986) and the absence of a papillate integument. Note that the level of secondary sclerotization can vary and in juvenile specimens the ventral shield is not formed (see below under Variability).

Variability. The degree of secondary sclerotization is age dependant. For example in juvenile specimens from Mumbulla Creek the ventral shield is still not formed as illustrated in Figure 7B . However, the structure of the palp ( Figure 7D ) in combination with a papillate integument ( Figure 7A ) allows easy identification of the new species.

Distribution. New South Wales.

Figures

FIGURE 5. Australiobates papillatus sp. nov., male holotype, unnamed creek at crossing with Dome Road: A—idiosoma, dorsal view (inset: details of integument; photograph); B—ventral shield (inset: genital field, partial view;2x enlarged); C— palp, lateral view; D—palp, medial view (inset: P4 ventral peg-like setae 2x enlarged); E—I-leg-5 and 6. Scale bars = 100 µm.

FIGURE 6. Australiobates papillatus sp. nov., paratype female, unnamed creek at crossing with Wyndham-Candelo Road: A—idiosoma, ventral view; B—I-leg-5 and 6. Scale bars = 100 µm.

FIGURE 7. Australiobates papillatus sp. nov., male (juvenile specimen) Mumbulla Creek: A—Details of integument (photograph); B—coxal field; C—genital field; C—palp, medial view; D—chelicera; E—I-leg-5 and 6. Scale bars = 100 µm.

FIGURE 8. Australiobates papillatus sp. nov., female (juvenile specimen), Mumbulla Creek: A—palp, lateral view; B— idiosoma, ventral view. Scale bars = 100 µm.