Geometric Morphometric Analysis of Ocular Patterns as a Species Identifier in the South African Endemic Trapdoor Spider Genus Stasimopus Simon, 1892 (Araneae, Mygalomorphae, Stasimopidae)

Abstract

The identification of Stasimopus Simon, 1892 species as well as mygalomorph species has been a long-standing challenge. This is due to their conservative morphologies as well as the lack of quantifiable characters. Ocular patterns have historically been used to aid in identification, but have largely been vague and subjective. This study was the first to test for phylogenetic signal in this character to validate its use for species identification and description as well as to test the viability of it in morphospecies and species identification. The results show significant phylogenetic signal for ocular patterns in both sexes, validating its use. The results display the evolutionary change in ocular patterns across various species. Species and morphospecies show distinct clustering in morphospace, but there is overlap due to the continuous shape of the character. The methodology of applying geometric morphometrics to quantify ocular patterns can distinguish between morphospecies and shows great promise for distinguishing species.