Morphology of the terminalia of the stick insect Dajaca napolovi from Vietnam (Insecta: Phasmatodea)

Abstract

Aschiphasmatinae is a small group of stick insects from the Oriental region whose genital morphology has been rarely described in detail. The subfamily is of particular interest, as phylogenetic studies have shown Aschiphasmatinae to be the sister group to the remaining Euphasmatodea. In this paper, the male and female terminalia are described for the first time in Dajaca napolovi Brock, a little known aschiphasmatine species from Vietnam. In the male, the transversally undivided abdominal sternum IX and gently incurved cerci with a conspicuous apical tooth represent apomorphies of Aschiphasmatinae. Thorn pads on the hind margin of abdominal tergum X consist of only a single row of 6–7 ventrally oriented teeth. The simple thorn pad structure of Aschiphasmatinae can represent an ancestral condition for Euphasmatodea. The vomer on venter X is well‐developed and features two unusually large basal apodemes and a strongly developed apical spine showing a specialized streaked surface micropattern. Female terminalia are characterized by an unkeeled abdominal sternum VIII covering the reduced primary ovipositor. Gonapophysis VIII does not extend beyond the tip of gonapophysis IX. An asymmetry concerning the size of the paired gonapophyses is reported for the first time in Phasmatodea.

Cretaceous winged stick insects clarify the early evolution of Phasmatodea

“…In general, the abdominal subgenital plate of Timema and most Euphasmatodea is transversally divided into an anterior sternite and a posterior sternite (the poculum) and covered the phallic organ (e.g. Sipyloidea amica Bei-Bienko, 1959, figure 6d,h and electronic supplementary material, figure S5) [5,37]. A similar character also occurs in P. erromera gen. et sp.…”

“…In males of living groups, distinctive morphological features mainly concern the abdominal sternum IX (subgenital plate) and the abdominal segment X, especially the venter X is particularly modified with specialized clasping organs involved in copulation [37]. In general, the abdominal subgenital plate of Timema and most Euphasmatodea is transversally divided into an anterior sternite and a posterior sternite (the poculum) and covered the phallic organ (e.g.…”

Physical constraints lead to parallel evolution of micro- and nanostructures of animal adhesive pads: a review

“…The high degree of convergence in the AMS of phasmids probably indicates adaptations to the surfaces encountered in the environment [108], as hypothesized in the literature [108,109,158,[161][162][163]. The disparity of AMS among the phylogenetic relationships, however, does not reveal a clear clustering of species with the same AMS as suggested by previous authors [1,[159][160][161]225]. The convergent presence of the same microstructures, in contrast, is a result of similar demands for adhesion in the respective habitats, which means that the physical rules of contact mechanics have a very strong influence on the adaptive evolution of the attachment structures in general.…”

“…A typical tarsus of Phasmatodea (Figure 4) consists of five tarsomeres. It is equipped with two claws and an arolium on the pretarsus, as well as euplantulae on the proximal four to five tarsomeres [1,2,109,161,162,225]. Except for the euplantulae of some Aschiphasmatini (Aschiphasmatinae) that are covered with adhesive setae [109], all attachment pads of Phasmatodea are smooth; however, they are covered with functional surface microstructures.…”

“…Never-theless, this also plays a role in host fidelity and potentially even speciation. Although the acquisition of flight supposedly has induced the diversification of attachment structures in insects (e.g., [1]), it is likely that in phasmids the convergent loss of flight ability [195,225] enhanced the host-plant dependence. The adaptation to specific plant surfaces due to a strong coevolution with plants enhances diversity even more.…”