Current understanding of the phylogenetic placement and higher-level systematics of the order Psocodea (“Psocoptera”+Phghiraptera) was reviewed. Recent molecular phylogeny and phylogenomics placed Psocodea to the sister of the Holometabola, but those studies could not reject the monophyly of Paraneoptera (Psocodea +Condylognatha) statistically. Therefore, monophyly of Paraneoptera, as strongly suggested morphologically, remains a well-founded and highly likely hypothesis. Monophyly of the Psocodea and the placement of Phthiraptera within the “Psocopteran” suborder Troctomorpha are well established morphologically and molecularly. Monophyly of all“Psocopteran” (Trogiomorpha, Troctomorpha including Phrhiraptera, and Psocomorpha) and Phthirapteran (Amblycera, Rhynchophthirina, and Anoplura) suborders is also well supported morphologically and molecularly, but monophyly of the Phthirapteran suborder Ischnocera is controversial.
In the studies of reptiles, I started the study of phylogeny and biogeography of the scincid genus, Plestiodon (formerly Eumeces) in the East Asian Islands by cladistic analysis and neighbor joining method based on morphological data. Then our laboratory has continued to study this group genetically using allozymes and DNA data. We revealed the process of the speciation of the genus in Japanese and Ryukyu Archipelagos. During the studying this group, we described five cryptic species. While studying the taxonomy and phylogeny of reptiles, I found that the cladistic taxonomy has several problems. I proposed the gradistic classification system showing cladistic relationship by putting a tag of the descendant grade within the ancestral grade.