Hesperomomonia similis, Smit, 2007

Smit, Harry, 2007, New Records of Hyporheic Water Mites from Australia, with a Description of Two New Genera and Ten New Species (Acari: Hydrachnidia), Records of the Australian Museum 59 (2), pp. 97-116 : 108-110

Hesperomomonia similis n.sp.

Figs. 37–41

Type material. HOLOTYPE female, Hortons Creek , hyporheic, at crossing with road Grafton-Armidale, 30°00.006'S 152°40.952'E, alt. 17 m, New South Wales, Australia, 6 November 2005 ( AMS).

Diagnosis. Large anterior dorsal plate with almost all dorsoglandularia in anterior half; large posterior dorsal plate with two dorsoglandularia; lateral of anterior large dorsal platelet only one minute platelet.

Description. Female: Colour pale. Idiosoma dorsally 818 long and 608 wide, ventrally 842 long. Dorsum with two large plates, the anterior plate 356 long and 535 wide, posterior plate 421 long and 510 wide. Dorsoglandularia on these plates lacking, only associated setae present. Anterior plate with postocularia and two pairs of associated setae, the posterior pair much closer to each other than the anterior pair; all pairs of associated setae almost in anterior half of plate. Posterior plate with two pairs of associated setae. Lateral of these large plates two platelets with glandularia, and two platelets without glandularia or associated setae. Moreover, two pairs of minute platelets lateral of large platelets. Eyes present but small. Ventral shield undivided. Capitular bay moderately deep and basally rounded. Suture lines of coxae incomplete and obliterated. Genital field pear-shaped, with three pairs of acetabula in gonopore, each pair of three acetabula on a small platelet. Genital field 153 long and 134 wide. Excretory pore closer to posterior idiosoma margin than to genital field. Chelicera two-segmented, 119 long. Lengths of PI–PV: 21, 70, 38, 74, 38 (excluding heavy seta). PIV enlarged, with two ventral heavy, pointed setae (one is probably broken); PV with a heavy terminal seta. Lengths of I-leg-4–6: 124, 330, 144; I-leg-6 typical for the family Momoniidae , with anteriorly a blunt, heavy seta, ending posteriorly pointed; I-leg-5 elongated. Claws of legs II-IV with large clawlet and small claw blade.

Etymology. Named for its similarity with the previous described species of the genus— Hesperomomonia humphreysi Harvey.

Remarks. The new species is close to H. humphreysi from Western Australia. It differs in the position of the setae on the anterior dorsal plate, in having two pairs of setae instead of three on the posterior dorsal plate and in the different number of platelets without glandularia lateral of the dorsal plates. The palp of the two species is very similar. Other differences are found in the large, heavy seta of I-leg-5: pointed in H. humphreysi and blunt in H. similis , while the posterior part of this segment is more slender in H. similis . Finally, I-leg-5 is much longer in the new species.

110 Records of the Australian Museum (2007) Vol. 59

Figures

Figs 37–41. Hesperomomonia similis n.sp., holotype female, (37) dorsal view; (38) ventral view; (39) genital field; (40) palp + capitulum; (41) I-leg-5–6. Scale bars 37–38 200 µm, 39–41 = 50 µm.