New and old species of Malaconothroidea from Europe (Acari, Oribatida) Gerd Weigmann Weigmann, G. (1997): New and old species of Malaconothroidea from Europe (Acari, Oribatida). -Spixiana 20/3: 199-218 The species Trln/pochthonius tectorum, T. nigricans, T. cladonicola (Trhypochthoni-idae), Mucranothrus nasalis (Mucronothridae) and Trhypochthoniellus longisetus (Trhypochthoniellidae) are redescribed. The description of Trln/pochthonius sphagni-cola, spec. nov. is presented, which is similar to T. nigricans. A new genus of Trhypochthoniidae, Altrhypochthonins Weigmann, 1997 has been established re-cently for Trhypochthonius badins, which is redescribed also. The european species Trhypochthoniellus crassus, T. excavatus and T. trichosus are regarded as junior Syn-onyms to the typical form of T. longisetus. T. setosus is regarded as a special form without sensilli of T. loiigisetus, having an intrasubspecific taxonomical Status: T. longisetus forma setosns. within a mixed population of both forms different intermediär and asymmetric specimens have been found. Prof. Dr. Gerd Weigmann, Zoological Institute, Lab. Soil Zoology and Ecology, Free University Berlin, Tietzenweg 85-87, D-12203 Berlin. Introduction The phylogenetic relations of the widely distributed genera Trhypochthonius and Trhypochthoniellus have not been cleared up in the last decades though van der Hammen (1956) "drew attention to the fact that studies of the genera Trhypochthonius and Trhypochthoniellus are still badly needed in order to arrive at a firmly defined diagnosis of the family" Trhypochthoniidae Willmann, 1931. Van der Hammen planned a revision of the genera but published some remarks on this item only (1956, 1959). Knülle (1957) clarified the relations between Trhypochthonius, Trhypochthoniellus, Malaconothnts and Trimalaconothrus and proposed three distinct families (Trhypochthoniidae, Trhypochthoniellidae and Malaconothridae), but subsequent taxonomists (cp. Gilarov & Krivolutsky 1975, Balogh & Mahunka 1983) did not follow him by leaving Trhypochthonius, Trhypochthoniellus and Mucronothrus in a single family Trhypochthoniidae (in this contribution I will deal with european genera only). Kunst (1971) established a new family Mucronothridae within his keys, without indicating it as new and without an explicite definition; this family has been ignored by subsequent authors. Main difficulties of a phylogenetic analysis resulted from insufficient descriptions of the type species (and others) of the mentioned genera, besides Malaconothrus and Trimalaconothrus (cp. Knülle 1957). It is the main task of this contribution to present redescriptions of important european species, including the type species, of Trhypochthonius, Trhypochthoniellus and Mucronothrus. These revisions led to a new phylogenetic analysis on the families and the genera (Weigmann 1997a), a new genus {Altrhypochthonins Weigmann, 1997) and a new species {Trhypochthonius sphagnicola, spec. nov.). The mentioned families have been included into the Crotonioidea (= Nothroidea auct.) by most of the taxonomists, but Haumann (1991) separated the Malaconothroidea (as "Trhypochthonioidea"), including the families and genera this paper deals with. 199
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