Different stages of spermatogenesis in antlion species Palpares libelluloides (1–3), Acanthaclisis occitanica (4), Distoleon tetragrammicus (5–8) and owlfly species Libelloides macaronius (9–10) after standard staining (1) and FISH with the 18S rDNA and telomeric (TTAGG)n probes (2–10). 1–3 MI, n = 12 + X + Y 4 diakinesis/MI transition, n = 8 + X + Y 5, 6 MI, n = 7 + X + Y 7 pachytene 8 spermatids 9 mitotic metaphase 10 spermatids. Asterisks mark sex chromosomes; red signals identify the (TTAGG)n - positive telomeres (arrowed); green signals identify rDNA clusters. Scale bar on Fig. 2 also applies to Figs 3–10.