Records of the Western Allstrall!lll M 11 se 11 III 19: 443-450 (1999) Two new freshwater mites of the genus Limnohalacarus (Halacaridae: Acari) from Australia Ilse Bartsch Forschungsinstitut und Naturmuseum Senckenberg, Notkestr. 31, 22607 Hamburg, Germany Abstract From Australia, two new species of the genus Limllohalacarl/s are described. LllllllohalacarI/s allstralis sp. novo from a sinkhole in the east Kimberley, Western Australia, and LimllohalacarI/s bi/labollgls sp. novo from Corndorl Billabong, Kakadu National Park, Northern Territory. A key is given to the females of this cosmopolitan genus. INTRODUCTION In the dry season (April-October), the Magela The superfamily Halacaroidea, with the single Creek contracts into a series of large pools family Halacaridae, comprises almost 900 marine (billabongs), one of those is the Corndorl billabong. and 50 freshwater species, the latter inhabiting both The halacarid mites were collected as part of an epigean and hypogean waters (Bartsch, 1996). From Environmental Impact Study. Australia, the first record of a freshwater halacarid The mites are mounted in glycerine-jelly. One of mite is that of the enigmatic Astacopsiphaglls the holotypes is deposited in the Western parasiticlls Viets, 1931, a parasite found fixed to the Australian Museum, Perth (WAM), the other in the gills of a parastacid crayfish (Viets, 1931). More Museum & Art Gallery of the Northern Territory, than five decades passed by till a second species Darwin (NTM), paratypes are in the NTM, WAM, was added to the fauna of Australia, a species of Senckenberg Museum Frankfurt (SMF), and the widely spread genus Lobohalacarus, L. bllnurong Zoologisches Institut und Zoologisches Museum, Harvey, 1988, extracted from the sediment of a river Hamburg (ZMH). bed (Harvey, 1988). Two years later, Harvey (1990) Abbreviations used in the description are: AD, reported on the first Australian representative of anterior dorsal plate; AE, anterior epirneral plate; Linll1ohalacarlls. It is a cosmopolitan genus, known GA, genitoanal plate; GP, genital plate; Oc, ocular from all continents except Antarctica which has as plate(s); 1'-1 to 1'-4, first (basal) to fourth (apical) yet not been studied intensely in respect to its palpal segment; PO, posterior dorsal plate; PE, lirnnic halacarid fauna. In this paper, two species posterior epimeral plate; sgs, subgenital setae. Legs are described, one from the east Kimberley, Western numbered I to IV. Australia, the other from the Kakadu National Park, Northern Territory. SYSTEMATICS MATERIAL AND METHODS Subfamily Limnohalacarinae Viets, 1927 One of the halacarid species was taken by S. M. Genus Limnohalacarus WaIter, 1917 Eberhard in the course of investigations of caves in the Napier Range, part of the Devonian Reef in the Type Species Kimberley, Western Australia. It is a large and Linll10halacarlls wackeri (WaIter, 1914), by original highly karstic limestone reef, extending for more designation. than 200 km. The collecting site, in the Donnas Drain, is a water-filled low passage with muddy Diagnosis floor, sediment banks at the waters edge, and many AD, OC and I'D generally reticulated. Idiosoma tree roots suspended in the water. The collection with five pairs of gland pores, two or three pairs of was made by sweeping a handnet through the dorsal setae and pair of adanal setae. AE with three water and amongst the tree roots. pairs of ventral setae; PE with three setae. Female The other species is from Corndorl Billabong, near CA with three to ten pairs of perigenital setae, male Jaribu. In the wet season it is a part of the Magela CA with larger number of setae. External acetabula Creek system which flows into the East Alligator arranged along margins of GA. Gnathosoma with River, Kakadu National Park, Northern Territory. large base. Second pair of long maxillary setae on 444 I. Bartsch rostrum. Palps four-segmented; P-2 enlarged; P-3 Description with large spine; fourth segment with six setae and a large spine. Tibia III with two bipectinate Female ventromedial setae. Tarsi I to IV with 1, 0, 0, ° Idiosoma 288 pm long, 205 pm wide. Dorsal plates ventral setae and, with dorsolateral solenidia reticulated, each polygon subdivided. AD included, 4, 4, 4, 3 dorsal setae. Tarsi ending with rectangular, 75 pm long, 64 pm wide (Figure lA); two claws; claws on tarsi II to IV with numerous pair of gland pores small, placed anterolaterally. long tines. Second pair of gland pores ventromarginally, within striated integument between AE and PE (Figure 18). QC divided transversely; anterior plate rounded, 35-38 pm in diameter; lateral margin with Limnohalacarns allstralis sp. novo pore canaliculus. Postocular plate slender, Figures 1-2 triangular, 30 pm long, 11 pm wide; with gland Material Examined pore anterolaterally. Fourth and fifth pairs of gland pores within striated integument, fourth pair Holotype adjacent to insertion of leg IV, fifth pair near 2, Donnas Drain (Karst index number KN-42), posterior margin of PD. PO 176 pm long, 92 pm Kimberley, Western Australia, Australia, 17°15'11"S, wide, 1.9 times longer than wide. Dorsal setae 124°41'46"E, 20 July 1998, S. M. Eberhard (WAM small, first pair of setae inserted close together in a 99/2164 BES6166). raised portion of AD; second pair within striated A ac----.""" G D E F Figure 1 Limnohalacarus allstralis sp. nov., female: A, idiosoma, dorsal aspect; B, idiosoma, ventral aspect; C, gnathosoma, ventral aspect; D, gnathosoma, lateral aspect; E, tip of rostrum and chelicera; F, third and fourth palpal segment, lateral aspect; G, tarsus I, lateral aspect (medial setae and claw omitted); H, tarsus H, lateral aspect (medial setae and claw omitted). (ac, acetabula; as, adanal seta; gIp, gland pore; p, basiventral process; pc, pore canaliculus; ph, pharyngeal plate; so, solenidion) Scale lines 50 J.lIn. Two new freshwater halacarid mites from Australia 445 integument anterior to OC; third pair of setae on 17 pm long and 1'-4 9 pm long. 1'-2 with onc very I'D at approximately 0.37 (relative to length of I'D, short and onc long seta. Ventromedial spine of 1'-3 from anterior to posterior) and close to lateral 19 pm long (Figure IF). margin. Adanal setae on anal plate seen at ventral Legs I and II shorter than legs III and IV (Figure aspect (Figure IB). 2). Genua I and II shorter than telofemora and tibiae Ventral plates delicately porose; marginal areas of (Figure 2A and B); telofemora I and II about as long PE foveate. AE 110 pm long, 168 pm wide, posterior as these legs' tibiae. Genua and telofemora of legs margin truncate. Pair of platelets posterior to AE III and IV almost equal in length (Figure 2C and D); (Figure 1B). PE 137 pm long; with one dorsal, one tibiae III and IV much longer than telofemora III lateral and one ventral seta. GA 147 pm long, 122 and IV respectively. Integument of lateral flanks of pm wide; with eight and nine acetabula along leg segments with epicuticular droplets. Tarsi I to lateral and posterior margin. One of the three pairs IV each with a basiventral process, dentiform at of perigenital setae close to anterior margin of GA, lateral aspect (Figure IG). Membranes of claw the other two pairs of setae slightly anterior to fossae narrow. Setation of legs, from trochanter to genital opening. Pair of genital sclerites wide, each tarsus (parambulacral setae and solenidia included): sclerite with two subgenital setae. leg I, 1, 4, 4, 6, 7, 7; leg II, 1, 3, 4, 6, 6, 6; leg Ill, 1, 2, Gnathosoma 100 pm long, 63 pm wide, 3, 4, 7, 6; leg IV, I, 1, 3, 3, 6, 5. Tibiae I and II each length:width ratio 1.6. Base of gnathosoma globular; with bipectinate ventromedial seta; tibia III with rostrum very slender. Pharyngeal plate 34 pm long, two strongly bipectinate ventromedial setae; on 18 pm wide, far from reaching posterior margin of tibia IV all setae smooth. Solenidion on both tarsus I gnathosomal base (Figure lC). Tip of rostrum and II (Figure IG and H) on dorsolateral membrane narrowed (Figure lE). Palps extending beyond of claw fossa, adjacent to dorsal fossary seta. rostrum (Figure ID). 1'-1 short, 5 pm long; 1'-2 Famulus not seen. All tarsi with pair of single enlarged, along its dorsal margin 45 pm long; 1'-3 parambulacral setae. Figure 2 LllllllolzalaCilrlh illl~lmllS no\'., female: A, I, nll'dlal aspect; B, 11, medial aspect; C Ill, medial aspect; D, IV, mcdizl! aspect of trochanter broken, """nl"nwnt".! bn)ken line) Scale line 50pm. 446 I. Bartsch Tarsi end with pair of claws; each of the claws ditches and deep crevices on islands of the Lesser with basal process. Claws of tarsus I apically with Antilles, Caribbean area (Viets, 1940). The two to three slender tines (Figure IG); basal process homeland of L. inopinatus is not known; individuals with two tines. Claws on the other tarsi with of the species were found in Belgium, in fish accessory process and 10-12 tines; basal process aquaria with cichlids (Fain and Lambrechts, 1987). with three tines. Limnohalacarus billabongis sp. novo Remarks Figures 3-5 The most marked characters of adult Limnohalacarus australis are: ventral plates AE, PE Material Examined and GP separate, and claws on tarsus I with few small tines and a basal process. The three species L. Holotype africanus Waiter, 1935, L. capemaumi Petrova, 1966 9, Corndorl Billabong, 12°38'S, 132°53'E, Magela and L. wackeri (WaIter, 1914) have separate ventral Creek system, Kakadu National Park, Northern plates but differ from L. australis by their claws of Territory, Australia, sample no. PAl, 1 March 1983, tarsus I which bear numerous long tines. Two M. Malipatil, J.