Ascid mites are an important component of the predatory meiofauna in soil, onvegetation, and in association with other animals, yet the Australian fauna isalmost unknown. At least 15 genera of ascid mites occur in Australia, of which14 genera and 26 species are treated in this paper. Four of these genera(Gamasellodes, Hoploseius,Platyseius,Xenoseius) are hererecorded from Australia for the first time. Six new species are described[Antennoseius(Antennoseius)lobochelus, sp.nov., Arctoseius memnon, sp. nov.,Gamasellodes plaire, sp. nov.,Platyseius cupensis, sp.nov., Xenoseius elizae, sp. nov., andZerconopsis pristis, sp. nov.], and six otherspecies are reported from Australia for the first time[Arctoseius semiscissus(Berlese),Gamasellodes rectiventris Lindquist,Proctolaelaps aurora(Vitzthum),Proctolaelaps bickleyi(Bram), Proctolaelaps lobatus De Leon, andProtogamasellus massula (Athias-Henriot)].Proctolaelaps nesbitti (Womersley) is removed fromsynonymy with P. pygmaeus (MÜller). Lectotypes aredesignated for Proctolaelaps antennatusKarg andP. australis Stone.P. antennatushas wrongly been recorded from Australia, and is known only from New Zealand.The first observations of feeding behaviour of mites in the generaIphidozercon, Xenoseius andZerconopsis confirm that nematophagy is prevalent amongsoil Ascidae. Keys to the world genera and Australian species areprovided.Protogamasellopsis Evans and Purvis istransferred to the Rhodacaridae, TangarorellusLuxton toan unspecified family in the Rhodacaroidea, andLindquistoseius Genis, Loots & Ryke to theOlogamasidae. OrolaelapsDeLeon is removed from synonymywith Melichares Hering. The following new synonymies areproposed: Arctoseius bicuspidatus Willmann, 1949 andArctoseius limburgensis Nesbitt, 1954 =Arctoseius semiscissus (Berlese, 1892);Cheiroseius (Posttrematus) Karg,1981 = EpiseiusHull,1918;Iphidozercon californicus Chant,1963,Leioseius (Arctoseius)elegans Bernhard, 1963 andIphidozercon variolatus Ishikawa, 1969=Iphidozercon corticalisEvans, 1958;Garmania longipilis Chant, 1958=Proctolaelaps aurora(Vitzthum, 1925);Proctolaelaps lewisi Garman & McGregor, 1956= P. utahensis Chant, 1958;Lasioseius convivavar.laevisternus Berlese, 1916a =Proctolaelaps pygmaeus(MÜller,1859);Neojordensia lativentris Karg, 1982 =Africoseius areolatus Krantz, 1962.

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SUMMA1YPopulations of the grasshopper Podis,na pedestris were collected from two ends of a zone of hybridization between two chromosome races, at Seyne and Tende in southern France. 21 enzyme and protein loci were detected by gel electrophoresis. Six of these loci showed widespread polymorphism, and a further eleven had very little or no variation. Two loci (Idh, 6Pgd) had rare alleles in different frequencies in the two areas surveyed. The remaining two loci (Mdh-1, Mdh-2) showed a marked increase in the frequency of rare variants, from 1 per cent outside the hybrid zone, up to 5 per cent at its centre. This region of increased electrophoretic variation coincided with the chromosomal dine between the two races, and with a region of decreased viability. It was spread over about the same width as the chromosomal dine. Possible explanations for this extra variation include intragenic recombination and elevated mutation rates.

The Australian fauna of the mite genus Macrocheles Latreille is revised. The fauna is shown to comprise 49 species, 26 of which are here described as new:M. agilis, sp. nov., M. angustus,sp. nov., M. borealis, sp. nov.,M. denhamensis, sp. nov., M. eta,sp. nov., M. forceps, sp. nov.,M. fungicolus, sp. nov., M. gamma,sp. nov., M. guttatus, sp. nov.,M. halli, sp. nov., M. holmi, sp.nov., M. howdenorum, sp. nov.,M. lama, sp. nov., M. lambda, sp.nov., M. omicron, sp. nov.,M. peckorum, sp., nov.,M. rimbija, sp., nov.,M. siderolophus, sp. nov.,M. spatei, sp., nov.,M. spiculatus, sp. nov.,M. tesselatus, sp. nov.,M. undoolya, sp., nov.,M. upsilon, sp. nov., M. waitei,sp. nov., M. wallacei, sp. nov. andM. zeta, sp. nov. A further 23 previously describedspecies are now known from Australia: M. aestivusHalliday, M. boudreauxi Krantz,M. faveolus Halliday,M. feehaniHalliday, M. glaber(MÜller), M. kappaHalliday,M. kraepelini (Berlese),M. krantzi Evans & Hyatt,M. mammifer Berlese, M. merdarius(Berlese), M. muscaedomesticae (Scopoli),M. mykytowyczi Womersley,M. novaezelandiae Emberson,M. paralius Halliday,M. penicilliger (Berlese),M. peniculatusBerlese,M. peregrinus Krantz,M. perglaber Filipponi & Pegazzano,M. robustulus (Berlese),M. similis Krantz & Filipponi,M. subbadius(Berlese),M. tenuirostris Krantz & Filipponi,M. virgo Halliday.Macrocheles hyatti Krantz & Filipponi has beenrecorded from Australia in error, and occurs only in New Zealand.Macrocheles scutatus (Berlese) is known from Australiaonly from a quarantine interception.Macrocheles lyallpurensis nom. nov. is proposed as areplacement name for M. krantzi Anwarullah & Irshadfrom Pakistan (preoccupied by M. krantzi Evans & Hyatt). A key is provided for the identification of all Australian species.