Family BLATTELLIDAE
Compiler and date details
A.M.E. Roach & D.C.F. Rentz, CSIRO Entomology, Canberra, Australian Capital Territory, Australia
Introduction
The Blattellidae are the largest known family in the Blattodea with more than 200 genera and some 1700 species. They are widespread in Australia, occurring in most habitats. To date, more than 20 genera have been recognised and more are likely to be discovered as the group becomes better known.
Most blattellid species are small in size, long-legged and very fast-moving. At any given locality, several species may be encountered. A number occur as commensals in the burrows of other animals and some live in caves. The majority are nocturnal but some are crepuscular and others diurnal. The most brilliantly coloured are members of the genus Ellipsidion Saussure which can often be seen sunning themselves on leaves or flowers. Their bright orange colours suggest membership in mimicry complexes. Mimicry occurs in other blattellids: Anaplecta Burmeister species are small and beetle-like and apparently mimic chrysomelid beetles of the genus Monolepta Dejean. One of Australia's most unusual cockroaches in the Blattellinae, Trogloblatta nullarborensis Mackerras, is a large, troglodytic species found deep within the limestone caves of the Nullarbor Plain. It is eyeless, has greatly reduced wings and tegmina, and the males have large dorsal glands.
Some of the world's most important cockroach pests are blattellids. These include the German Cockroach, Blattella germanica (Linnaeus) and the Brown-banded Cockroach, Supella longipalpa (Fabricius), both of which are notorious transmitters of disease. Two Australian species are considered as pests. Paratemnopteryx couloniana (Saussure) enters houses and restaurants and infests kitchens and pantries. The Orchid Cockroach, Shelfordina orchidae (Asahina), causes concerns to orchid growers when it is found in their glasshouses where it lives in the potting mix. Whether the species causes damage or is just a harmless commensal has yet to be determined.
The Blattellidae are presently being revised by Roth and Grandcolas: the generic composition of the group, their limits and characteristics are far from stable. The family has been divided into subfamilies with varying degrees of acceptance. The present trend is to follow a scheme laid out by McKittrick (1964) that involves knowing how the female rotates the oötheca at oviposition. As a result of the instability, many genera have been assigned 'provisionally' to one subfamily or another because the critical observations have not been made. Roth (1990a, 1990b, 1991, 1992) should be consulted for discussion of this problem.
References
McKittrick, F.A. 1964. Evolutionary studies of the cockroaches. Memoirs of the Cornell University Agricultural Experiment Station 389: 1–197
Roth, L.M. 1990a. A revision of the Australian Parcoblattini (Blattaria: Blattellidae: Blattellinae). Memoirs of the Queensland Museum 28: 531–596
Roth, L.M. 1992a. The Australian cockroach genus Choristima Tepper (Blattaria, Blattellidae: Ectobiinae). Entomologica Scandinavica 23: 121–151
Roth, L.M. 1990b. Revisionary studies on Blattellidae (Blattaria) from the Indo-Australian region. Memoirs of the Queensland Museum 28: 597–663
Roth, L.M. 1992b. The cockroach genus Allacta Saussure & Zehnter (Blattaria, Blattellidae: Pseudophyllodromiinae). Entomologica Scandinavica 23: 361–389
Roth, L.M. 1990. Revisionary studies on Blattellidae (Blattaria) from the Indo-Australian region. Memoirs of the Queensland Museum 28: 597–663
Roth, L.M. 1991. The cockroach genera Beybienkoa, gen. nov., Escala Shelford, Eowilsonia, gen. nov., Hensaussurea Princis, Parasigmoidella Hanitsch and Robshelfordia Princis. Invertebrate Taxonomy 5: 553–716