Arthropods in biodiversity hotspots: the case of the Phytoseiidae (Acari: Mesostigmata)

The biodiversity hotspot concept was defined by Myers in 1988 to determine priority areas for conservation. They have high endemism levels and have lost more than 70% of their original vegetated area. To date, there is little information on arthropod diversity in these zones. This work focuses on the biodiversity of the Phytoseiidae (Acari), one of the best known among the order Mesostigmata, in these threatened areas. These mites are usually predators and they are worldwide spread. Geographic distribution of phytoseiids in 27 biodiversity hostspots was assessed from data of the last world catalogue published in 2004. One thousand two hundred and thirty species are reported from at least one hotspot (62% of the total species number) and 604 species (30% of the total species number) are endemic to the 27 hotspots considered. The number of reports/publication in hotspot areas (2.6) is higher than in non-hotspot zones (1.5). Hotspots areas could be thus considered as a great reservoir of the Phytoseiidae diversity, just as they are for vertebrates and plants. Correlations between plant, vertebrate, mite diversity and endemism, as well as congruence rates between endemism levels of these three organisms suggest that the biodiversity patterns of plants and vertebrates mirror well those of the Phytoseiidae (both for endemicity and species richness). More intense conservation efforts in biodiversity hotspots would thus be assumed to affect plant and vertebrate biodiversity, as already known, but also arthropod biodiversity, as it was assumed. These results further support thus the importance of these zones in biodiversity conservation, even for organisms like mites, very small and poorly studied in this regards. More data on arthropods are, however, required to confirm these preliminary observations.