Blattodea
Blattodea is an order of insects that contains cockroaches and termites.[1] Formerly, the termites were considered a separate order, Isoptera, but genetic and molecular evidence suggests termites evolved from within the cockroach lineage, cladistically making them cockroaches as well. The Blattodea and the mantises (order Mantodea) are now all considered part of the superorder Dictyoptera. Blattodea includes approximately 4,400 species of cockroach in almost 500 genera, and about 3,000 species of termite in around 300 genera.
Termites are pale-coloured, soft-bodied eusocial insects that live in colonies, whereas cockroaches are darker-coloured (often brown), sclerotized, segmented insects. Within the colony, termites have a caste system, with a pair of mature reproductives, the king and the queen, and numerous sterile workers and soldiers. The cockroaches are not colonial but do have a tendency to aggregate and may be considered pre-social, as all adults are capable of breeding. Other similarities between the two groups include various social behaviours, trail following, kin recognition and methods of communication.
Cladistic analysis of five DNA sequences in 107 species representing all the termite subfamilies, all six cockroach families, including 22 of the 29 subfamilies, and five of the 15 mantis families (as out-groups) showed that the termites are nested within the cockroaches, and that the Cryptocercidae is a sister group to the termites. The mantids were shown to be the sister group to Blattodea.[2] Cryptocercus also shares characteristics such as species of gut bacteria with the termites.[3]
The cockroach families Lamproblattidae and Tryonicidae are not shown but are placed within the superfamily Blattoidea. The cockroach families Corydiidae and Ectobiidae were previously known as the Polyphagidae and Blattellidae.[4][5]
The evolutionary relationships of the Blattodea (cockroaches and termites), based on Eggleton, Beccaloni & Inward (2007) and modified by Evangelista et al. 2019, are shown in the cladogram:[6][7]
The cladogram shows the family Alienopteridae (originally assigned to its own order "Alienoptera") as sister to Mantodea; while it was reassigned to the extinct Blattodea superfamily Umenocoleoidea by Vršanský et al.,[8] a more recent analysis places Alienopteridae and Umenocoleidae as sister taxa within Dictyoptera, and not within Blattodea.[9]
