Electronic Supplement 6
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Organisms
Diversity & Evolution 6 (2006) Electronic Supplement 6 |
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Ilse Bartsch:
Halacaroidea (Acari): a guide to marine
genera.
print version: Org. Divers. Evol. 6(2): 103-108. 2006
electr. suppl.:
full article. pdf-format, 4.2 MB
Abstract:
Halacarid mites (Halacaroidea: Halacaridae) are meiobenthic organisms.
The majority of species and genera are marine, only few are restricted to
freshwater. Halacarid mites are present from the tidal area to the deep sea. It
is the only mite family completely adapted to permanent life in the sea. The
first record was published more than 200 years ago.
At present, 51 marine
and brackish water genera of halacarid mites are known, including more than
1000 species. The genera are Acanthohalacarus, Acanthopalpus,
Acarochelopodia, Acaromantis, Acarothrix,
Actacarus, Agaue, Agauides, Agauopsis,
Anomalohalacarus, Arenihalacarus, Arhodeoporus,
Atelopsalis, Australacarus, Bathyhalacarus,
Bradyagaue, Camactognathus, Caspihalacarus,
Coloboceras, Colobocerasides, Copidognathides,
Copidognathus, Corallihalacarus, Enterohalacarus,
Halacarus, Halacarellus, Halacaroides,
Halacaropsis, Halixodes, Isobactrus, Lohmannella,
Metarhombognathus, Mictognathus, Parhalixodes,
Pelacarus, Peregrinacarus, Phacacarus,
Rhombognathides, Rhombognathus, Scaptognathides,
Scaptognathus, Simognathus, Spongihalacarus,
Thalassacarus, Thalassarachna, Thalassophthirius,
Tropihalacarus, Werthella, Werthelloides,
Winlundia, and Xenohalacarus.
The guide, which includes
marine and brackish water genera, starts with an introduction to methods of
collection, extraction and examination of halacarid mites, an outline of the
external morphology and life history, and an overview of the commonly used
terminology. Both a dichotomous key and tabular keys to the genera are
presented. The keys have been prepared on the basis of adults. In general, in
adults and nymphs the outline of idiosoma, gnathosoma and legs is similar,
whereas the outline of plates, the sculpturing and number of setae on idiosoma
and legs differ. In the tabular keys idiosoma, gnathosoma, palps, legs, tarsi
and shape of claws are treated separately.
The major part of the guide
deals with descriptions of the 51 genera. Each genus is diagnosed and
illustrated, namely a dorsal and ventral aspect of the idiosoma, the
gnathosoma, leg I and tarsi I, II and IV. The diagnoses mention both,
characters expected to be relevant in a phylogenetic sense and those thought to
be mainly correlated with environment and mode of life. Rare character variants
are included in the diagnoses; more variants are expected to be found in the
future. In addition to the diagnoses, short notes are given on biology and
geographical distribution, on similar-looking genera, and distinguishing
characters. At the end of the presentation of a genus, relevant and most recent
descriptive or phylogenetic references are listed.
Key words: Halacaroidea; Acari, General introduction; Marine genera; Keys; Diagnoses
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