A new hygrobatid genus from Australia (Acari: Hydrachnidia: Hygrobatidae)

A BSTRACT — A new genus and tullyensis


INTRODUCTION
Australia is rich in hygrobatid genera. Until present 19 genera are known (Cook 1986, Harvey 1998, Smit 2009). On a global scale the number of hygrobatid genera is only surpassed by the Neotropics (Di Sabatino et al. 2008).
During a recent collecting trip in Queensland, Australia a new hygrobatid genus was collected, which will be described in this paper.

MATERIALS AND METHODS
The material has been collected by the author. The following abbreviations have been used: Cx-III = third coxal plates; P1-5 = palp segment 1-5; I-leg-4-6 = fourth-sixth segments of first leg; asl = above sea level; NP = National Park; QM = Queensland Museum, Brisbane. All measurements are in µm, measurements of palp and leg segments are of the dorsal margins. Coordinates were obtained with a GPS.
Diagnosis -Male: Dorsum with four large plates, anterior plate with a pair of postocularia, middle pair of plates each with one glandularium, posterior plate with a pair of glandularia. In the soft integument of dorsum four pairs of smaller glandularia platelets. Eyes present. Camerostome present, roof of camerostome with a short medial projection; capitulum attached to a long protrusible tube; chelicera stylet-like. Ventral shield present. Suture lines of fourth coxae absent, glandularia of fourth coxae lying anterior to IV-leg sockets. Anterior to the fourth leg sockets a short ridge. Male idiosoma with a posterior projection with the genital field, with three pairs of acetabula; genital field only well visible in posteromedial view. P3 without a ventral projection. Legs not modified, I-leg-5 without heavy ventrodistal seta. Swimming setae absent. Female: Unknown. Type species -Proboscibates tullyensis n. sp.
Etymology -Named for the trunk-like protrusible tube with the capitulum.
Remarks -The presence of a protrusible tube is found in a number of non-related genera, e.g. Limnesia Koch (Limnesiidae, some Australian species), Tubophora Walter (Limnesiidae, West Africa), Tubophorella K.O. Viets (Limnesiidae, Australia), Rhynchaustrobates Cook (Hygrobatidae, Australia), Rhynchaturus Besch (Hygrobatidae, S America), Pseudotorrenticola Walter (Torrenticolidae, Europe, West Africa, Asia), Psammotorrenticola E. Angelier (Anisitsiellidae, Europe), Clathrosperchon Lundblad (Rhynchohydracaridae, N and S America) (Cook 1974(Cook , 1988. This character is therefore of little use in delineating genera. In the presence of a camerostome, roof of the camerostome with a short medial projection, protrusible mouthparts, large dorsal plates and a ventral shield the new genus is most close to the subgenus Victoriabates Cook, 1986 of Rhynchaustrobates. The new genus differs in the posterior idiosoma projection with the genital field, the wide gonopore, the absence of posterior suture line of the fourth coxae and the short ridge anterior to the fourth leg sockets. These differences, especially those of the genital field, are large enough to warrant the erection of a new genus.
Etymology -Named after the Tully Gorge NP with the Tully River.