FIGURE 4:

(A) Many insects, such as the caddisfly Stenophylax permistus (left), have unusual sperm axonemes with 9 accessory microtubules surrounding the 9 microtubule doublets in a 9+9+2 configuration (right; adapted from Dallai et al. [2016] and reprinted with permission from the Annual Review of Entomology). (B) The sperm axoneme accessory microtubules of the mantidfly M. perla have 40 protofilaments and are the largest microtubules observed in nature (adapted from Dallai et al. [2005] and reprinted with permission from Elsevier).