Support for the underrepresented sex: new descriptions of scutacarid males (Acari, Heterostigmatina).

Based on males gained from laboratory cultures, nine new descriptions and one redescription of scutacarid males are given: the respective species are Heterodispus foveatus Jagersbacher-Baumann and Ebermann 2012, Imparipes dispar Rack, 1964, Lamnacarus ornatus Balogh and Mahunka, 1963, Scutacarus acarorum (Goeze, 1780), S. deserticolus Mahunka, 1969, S. ellipticus Karafiat, 1959, S. longipes Rack, 1975, S. longitarsus (Berlese, 1905), S. tackei Willmann, 1942 and S. tyrrhenicus Ebermann, 1986. The taxonomic relevance of male morphology is evaluated. It reveals a strong potential for differentiating between species, and possible characters diagnostic for scutacarid genera are discussed. Within Heterostigmatina, males of Scutacaridae show the most derived characters.

Hidden in the mangrove forest: the cryptic intertidal mite Carinozetes mangrovi sp. nov. (Acari, Oribatida, Selenoribatidae).

The small archipelago of Bermuda is a geologically young landmass in the Western Atlantic Ocean and recently turned out to be inhabited by a number of intertidal oribatid mites. One newly described species, Carinozetes bermudensis, showed an unusual vast range of habitats like sandy beaches, rocky substrate and mangroves. In the present study, 13 Bermudian populations of C. bermudensis were analysed to verify species integrity of specimens from different microhabitats. A morphometric analysis of 17 continuous variables as well as a molecular genetic investigation of the mitochondrial cytochrome oxidase subunit I revealed the existence of a new species Carinozetes mangrovi sp. nov., inhabiting exclusively intertidal algae growing on mangrove roots. Although both species are morphologically nearly identical, the configuration of the genus-specific ventral carinae represents a clear diagnostic character. The high genetic divergence of approximately 12 % of the cytochrome oxidase subunit I gene sequence between C. bermudensis and C. mangrovi sp. nov. suggests that these two species diverged before the emergence of the Bermuda islands. Accordingly, both of them are older than the geologically young archipelago of Bermuda.

Species differentiation of scutacarid mites (Heterostigmatina) using multivariate morphometric methods.

The genera of the mite family Scutacaridae (Heterostigmatina) can be easily distinguished by certain qualitative traits, whereas the species of these genera are lacking conspicuous distinctive features and thus, species descriptions are often based on quantitative characters. However, the intraspecific variability of these traits can be pronounced and the applicability of multivariate morphometric methods for species differentiation has not been studied so far. In the present study, four members of the genus Scutacarus, referred to as the acarorum species-complex, were analysed using traditional and geometric morphometric methods. The results showed that multivariate morphometric methods are perfectly suitable for differentiating even between morphologically similar scutacarid species, with traditional morphometrics performing better than geometric morphometrics. Despite their morphological similarity, morphometric analyses support the species status of the four members of the species-complex.

Methods for rearing scutacarid mites (Acari, Heterostigmatina) and the influence of laboratory cultures on morphometric variables.

Mites of the soil inhabiting family Scutacaridae (Heterostigmatina) are distributed throughout the world, but only rarely found in high densities. Larvae and males are extremely difficult to detect and identify in soil samples. Laboratory cultures are necessary to describe these life stages, detect female dimorphism, or carry out other kinds of biological study. The present paper gives an historical overview of the methods applied for rearing scutacarids, demonstrating that thus far the use of glass tubes stuffed with soil is the most valuable method. Morphometric comparisons between field collected and laboratory reared specimens of two scutacarid species, Scutacarus acarorum Goeze and Heterodispus foveatus Jagersbacher-Baumann and Ebermann, revealed a clear influence of environmental conditions on the phenotype of laboratory-reared mites. Size correction minimized the environmentally induced variation and should therefore be mandatory for classification of species based on morphometric variables. Taxonomic assignment of laboratory reared scutacarids is possible, but must be done with extreme caution.