The role of abiotic and biotic factors in the unequal body shape diversification of a Gondwanan fish radiation (Otophysi: Characiformes)

Understanding why some clades diversify greatly while others do not is a major goal of evolutionary biology. Both abiotic and biotic factors are important in driving unequal morphological diversity across the tree of life. However, few studies have quantified how abiotic habitat and community composition differences influence unequal morphological diversification in spatiotemporally diffuse radiations. We use geometric morphometrics, abiotic habitat data generated by Geographic Information Systems (GIS) analyses, evolutionary simulations, and phylogenetic comparative methods to determine whether random evolution, habitat variation, competition for niches, or a combination of factors influenced the unequal body shape diversity of a Gondwanan freshwater fish radiation. We find that Neotropical characiform lineages, which exhibit substantially more body shape diversity than their African counterparts, occupy significantly more slope and elevation habitats than African lineages. Differences in habitat occupation between the continental radiations occur through a combination of likely competition with cypriniform fishes in Africa restricting access to higher slope and elevation habitats and significantly more low-elevation and slope habitats available in the Neotropics. Our findings suggest that spatiotemporally widespread radiations, like Characiformes, do not diversify across homogenized habitats and biotic assemblages, with differences in community structure and physical habitat playing an important role in driving unequal morphological diversification.

The soil mite genus Conchogneta (Acari, Oribatida, Autognetidae), with new findings from Mongolia

This work deals with taxonomy, geographical distribution as well as known ecology of oribatid mites of the genus Conchogneta Grandjean, 1963 in the world. The majority of species belonging to this genus is known to be widely distributed in Europe, but only three of them are found in other areas of the northern hemisphere. Most species of Conchogneta are inhabitants of litter of various types of forestas, terricolous and epiphytic bryophytes, epiphytic lichens, and soil of steppe, river valleys, moor, oligotrophic bogs, floodland assemblages etc. A new species, Conchogneta glabrisensillatasp. n. is described, and another species, Conchogneta traegardhi (Forsslund, 1947) is redescribed from the northern and western parts of Mongolia, respectively. Conchogneta is recorded for the first time for the fauna of Mongolia. The species status of Conchogneta dalecarlica (Forsslund, 1947) is discussed. Species descriptions are accompanied with detailed illustrations. Furthermore, a key is provided for the identification of adults of the known species of Conchogneta in the world.