David Evans Walter

Feeding behaviour and phylogeny: observations on early derivative Acari

Based on laboratory observations of three species of Allothyrus (Parasitiformes: Holothyrida: Allothyridae) from south east Queensland and gut content analysis of 62 individuals representing 11 species of Allothyrus from eastern Australia, we determined that Australian Allothyridae are scavengers that ingest fluids only. Living arthropods, nematodes, snails and annelids were ignored, but dead arthropods were readily fed upon and were sufficient to maintain adults and nymphs for many months. The adults were sluggish, timid animals that relied on armour, thanatosis and probably on noxious chemicals for protection: the juveniles produced secretions from idiosomal glands. In contrast, most early derivative Mesostigmata that we tested (Sejina, species of Sejus and Uropodella; Uropodina, Polyaspis sp. and Cercomegistina, an undescribed Asternoseiidae) were aggressive predators of small invertebrates and ingested fluids only; however, two species of Asternolaelaps (Sejina) had solid fungal and animal material in their guts. Similarly, the early derivative acariform (Palaeosomata, species of Stomacarus and Loftacarus) and opilioacariform mites (an undescribed Opilioacarida from Australia) that we examined all ingested particulate foods, including fungal and animal material. These observations are consistent with the hypothesis that the earliest mites were scavengers and opportunistic predators that ingested solid foods and that fluid feeding is a derived condition linking the three orders of Parasitiformes (Holothyrida, Ixodida and Mesostigmata).

Exotic vs endemic biocontrol agents: Would the real stratiolaelaps miles (Berlese) (Acari : Mesostigmata : Laelapidae), please stand up?

The ability of introduced organisms to invade undisturbed native habitats is a major concern in conservation biology and has resulted in a re-evaluation of the introduction of exotic biocontrol agents, especially of generalist predators. One such agent is Stratiolaelaps miles (Berlese), a predatory mite described from Italy, known from throughout the Holarctic, and apparently accidentally introduced to other areas of the world, including Australia. Initial investigations revealed that putative S. miles could be found in both disturbed and relatively pristine habitats in Queensland, Australia. However, analysis of the mitochondrial DNA of five populations showed most to be highly divergent genetically. Subsequent morphological analysis established two species groups: the lamington-group from cool-temperate to subtropical rainforests in Eastern Australia and the more eurytopic miles-group with a cosmopolitan distribution. We describe two new species from each of these complexes (Stratiolaelaps womersleyi, Stratiolaelaps lamington; Stratiolaelaps marilyn, Stratiolaelaps lorna, respectively), and resurrect Stratiolaelaps scimitus (Womersley), a species which often appears to have been confused with S. miles. Additionally, the large genetic distances among morphologically homogenous species in the miles-group suggest that the apparently cosmopolitan S. miles may be composed of a suite of cryptic species of potentially varying utility in biological control

A review of the genus Asca (Acarina : Ascidae) in Australia, with descriptions of three new leaf-inhabiting species

Australian mites in the genus Asca were last reviewed in 1956 when the first three Australian species were described. We here provide diagnoses for those species, describe three new species (Asca macromela, A. grostali and A. mindi) from the leaves of rainforest trees, and report on the occurrence in Australia of a species described from New Zealand (A. porosa Wood) and of a cosmopolitan thelytokous species (A. garmani Hurlbutt). Keys to the eight species and the three species-groups they represent are provided. Examination of 13 266 leaves from 193 species of woody plants in eastern Australian forests indicated that Asca mites are abundant and diverse inhabitants of tropical rainforest canopies, but decline in both diversity and abundance with increasing latitude.

The distributions of parthenogenetic ascid mites (Acari: Parasitiformes) do not support the biotic uncertainty hypothesis

Fifteen out of 50 species of ascid mites (30%) that we collected from four synanthropic and seven natural habitats in North America and Australia existed as all-female populations. In contrast to the predictions of the biotic uncertainty hypothesis (i.e. that parthenogenetic species are rare, restricted in distribution and survive through dispersal ability), we found that parthenogentic ascid mites were present in ten out of 11 habitats sampled, but were not superior colonists. In a glasshouse experiment, pasteurized soil in pots was colonized first by bisexual species and only later by all-female species. Furthermore, a habitat requiring strong dispersal abilities (decaying fungal sporocarps) lacked parthenogenetic species and a review of literature and collections indicated that all-female ascid species rarely form the phoretic associations with insects necessary to exploit patchy and ephemeral resources. The assumptions that parthenogens are reproductively superior to but competitively inferior to sexual relatives were not supported by experiments comparing a bisexual and an all-female species of Lasioseius.

A review of the Australian Phytoseiinae (Acari : Mesostigmata : Phytoseiidae)

We revise the Australian Phytoseiinae (Acari : Mesostigmata : Phytoseiidae) based on a study of over 1000 slide-mounted specimens. Of the three currently recognised genera in the subfamily, only Phytoseius is known from Australia, but endemic species occur in each of its three species-groups. We describe 11 new species, including P. bunya, the first Australian representative of the purseglovei-group. The plumifer-gcoup is represented by five species including P. danutae, sp. nov. and P. improcerus Corpuz, a Philippine mite newly reported from Australia; in addition, P. leaki Schicha is newly reported from New Zealand. In Australia, the horridus-group contains two oceanic-island species, P. hawaiiensis Prasad and P. mayottae Schicha (newly reported), and two complexes of Australasian endemics. The fotheringhamiae-complex. has seven species, including three new species from tropical rainforests in far north Queensland - P. paluma, P. camelot and P. devildevil; in addition, P. fotheringhamiae is newly reported from New Zealand. The douglasensis-complex also has seven species, including six new species from Queensland and the Northern Territory: P. oreillyi, P. acaciae, P. brigalow, P. mantoni, P. darwin and P. litchfieldensis. All 22 species of Phytoseius known from Australia are keyed and diagnosed, and their distributions are detailed.

A jumping mesostigmatan mite, Saltiseius hunteri n. g., n. sp. (Acari: Mesostigmata: Trigynaspida: Saltiseiidae, n. fam.) from Australia

Abstract The Australian acarofauna contains a diversity of mesostigmatans that are difficult to fit within the existing higher level taxonomic framework. In this paper a new genus, Saltiseius, and a new family, Saltiseiidae, based on S. hunteri n. sp., an Australian mite with well developed jumping abilities is described. Although diagnosable as Cercomegistina, Saltiseius also shares some unusual character states with Micromegistus, which is usually placed in the Antennophorina.

Heatherellidae — a new family of Mesostigmata (Acari: Parasitiformes) based on two new species from rainforest litter in Australia

Abstact Forest litter habitats in Australia contain a diversity of early derivative Mesostigmata, including some taxa that cannot be placed in any currently recognised suborder. A new genus, Heatherella, and family, Heatherellidae, are proposed to accommodate two such new species, H. acanthocharis and H. callimaulos, that feed on nematodes and inhabit subtropical rainforest litter in southeast Queensland. Both mites share a number of derived character states otherwise unknown in the Mesostigmata, e.g. the opisthosoma is ringed by nine pairs of spout-like gland openings; the stigmatal opening is contained within a raised, spiky turret; the adults have three setose pygidial shields, and a unique circumventral shield surrounds the intercoxal region. The relationships of the Heatherellidae appear to be closest to the Uropodina; however, the new family lacks major uropodine synapomorphies and shares characters with Epicriina, Microgyniina, and Zerconina (none of which are known to occurin Australia).

A new species of Triplogyniidae (Mesostigmata: Celaenopsoidea) from Australian rainforests.

Abstract We report the first known occurrence of Triplogyniidae in Australia and describe a new species, Funkotriplogynium iagobadius, from subtropical to tropical rainforests in eastern Queensland. We use the ontogenetic addition of setae to tentatively assign designations using the system of Lindquist and Evans (1965). Adults and nymphs were common in bracket fungi growing on logs, and could be collected from forest litter, especially around logs. One individual was found on a passalid beetle (Pharochilus dilatus). Adults, nymphs and larvae are predators of insects, mites and nematodes. Triplogynium irapora Flechtmann is transferred to Funkotriplogynium.

A new mite from an arboreal ant (Formicidae: Polyrachis sp.): Myrmozercon iainkayi n. sp. (Mesostigmata: Laelapidae)

Abstract Previously, two species of Myrmozercon (= Myrmonyssus) have been described from ground-nesting Australian ants in the genus Iridiomyrmex. Herein a new species, Myrmozercon iainkayi, infesting workers and alate adults of a leaf-nesting species of Polyrachis ant is described. The new species has a number of unusual or unique characters, including coxal hypertrichy (6-6-6-4 for legs I-IV, respectively), and based on the structure of its mouthparts, appears to be a haemolymph-feeding parasite.

Two new species of the genus Ceratotarsonemus (Acari: Tarsonemidae)

Abstact Two new species of tarsonemid mites, Ceratotarsonemus alasand C. hexagonalis, are described and illustrated. Notes on field characteristics and host relationships as well a key to the species of Ceratotarsonemus are included. Ceratotarsonemus teqmen Lin & Zhang is transfered to the genus Tarsonemus.