| Abstract: | We studied species richness patterns of obligate subterranean (troglobiotic) beetles
in the Dinaric karst of the western Balkans, using five grid sizes with cells of 80×80,
40×40, 20×20, 10×10, and 5×5 km. The same two hotspots could be recognized
at all scales, although details differed. Differences in sampling intensity were not sufficient
to explain these patterns. Correlations between number of species and number of
sampled localities increased with increasing cell size. Additional species are expected
to be found in the region, as indicated by jackknife 1, jackknife 2, Chao2, bootstrap,
and incidence-based coverage (ICE) species richness estimators. All estimates increased
with increasing cell size, except Chao2, with the lowest prediction at the intermediate
20×20 km cell size. Jackknife 2 and ICE gave highest estimates and jackknife 1 and
bootstrap the lowest. Jackknife 1 and bootstrap estimates changed least with cell size,
while the number of single cell species increased. In the highly endemic subterranean
fauna with many rare species, bootstrap may be most appropriate to consider. Positive
autocorrelation of species numbers was highest at 20×20 km scale, so we used this
cell size for further analyses. At this scale we added 137 localities with less positional
accuracy to 1572 previously considered, and increased 254 troglobiotic species considered
to 276. Previously discovered hotspots and their positions did not change, except for
a new species-rich cell which appeared in the south-eastern region. There are two
centres of troglobiotic species richness in the Dinaric karst. The one in the north-west
exhibited high species richness of Trechinae (Carabidae), while in the south-east, the
Leptodirinae (Cholevidae) were much more diverse. These centres of species richness
should serve as the starting point for establishing a conservation network of important
subterranean areas in Dinaric karst.
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