Sexual dimorphism in some morphological traits of three european millipedes (Diplopoda, Julida, Julidae)

Abstract

Sexual size and shape dimorphism (SSD and SShD) are understudied phenomena in millipedes. In the present study, we investigated both kinds of sexual dimorphism in some morphological traits, as well as whether shape of the morphological traits varied more than their size. Three julidan species, viz., Pachyiulus hungaricus (Karsch, 1881), Megaphyllum unilineatum (C.L. Koch, 1838), and M. bosniense (Verhoeff, 1897), were used for these purposes. By means of traditional and geometric morphometrics, we found that SSD exists in linear measurements of the tested morphological traits, as well as SShD of the legs in all analysed species. Also, SSD of antennal centroid size was detected in P. hungaricus and M. unilineatum, in addition to SShD of antennae in P. hungaricus and M. bosniense. Our results indicate that morphological intersexual differences are species-specific and that the shape of some morphological traits varies more than the size of centroids of the same structures.