A Latitudinal Gradient in Species Richness of Subgenus Tetraconasoma Verhoeff, 1924, not Sphaerotherium Brandt, 1833 (Diplopoda: Sphaerotheriida)?

Abstract

The Tropical Conservativism Hypothesis and Biogeographical Conservativism Hypothesis were tested in forest millipedes. Latitudinal diversity gradient (LDG) was measured in the genus Sphaerotherium and Tetraconasoma to distinguish between the two hypotheses. There was a marginally significant correlation between the number of species and latitudinal degrees away from the equator in Tetraconasoma (r=-0.78091517, Z score=-1.48168825, n=5, p=0.06921166), not Sphaerotherium (r=-0.73029674, Z score=-0.92936295, n=4, p=0.17635049). The relationship in Tetraconasoma was shown to be significant (Spearman's Rho rs=-0.89443, p (2-tailed) = 0.04052). An evolutionary preference for temperate environments appearing to have led to climatic constraints on dispersal based primarily on precipitation seasonality gradients was previously suggested. The antennal cone cells in the Tetraconasoma are suggested to be responsible for this sensory adaptive radiation and variation.