Figure 15

Segmental composition of the anterior trunk in julidan millipedes. Segmental composition of the anterior part of the body in the homeotic specimen of Ommatoiulus moreleti described in this paper, compared to a normal male, as suggested by the multiplicative segmentation model [15–17, 28]. The first trunk rings are the legless collum and 3 rings with one leg pair each, followed by typical diplosegments. In the homeotic specimen, only one ring (13 + 14) corresponds to leg pairs 20–23. In each panel, the left vertical sequence of circles represents the embryonic head (big circle) followed by a few primary segments (smaller circles), the number of which is left indeterminate (fading empty circles toward the posterior). Each primary segment is subsequently split, through a sequence of binary AP divisions, into a growing number of secondary (definitive) segments. The intermediate stages from primary to secondary segments as well as the secondary segments (rings, R) and the associated pairs of appendages (A) are represented as squares. Appendage pairs are numbered.