Proturans of British Columbia

PROTURA OF BRITISH COLUMBIA

Introduction

Tuxen (1964) recognizes two suborders and three families in this Order, all of which occur in North America. Only the family Acerentomidae in the suborder Acerentoniodea has so far been recorded in British Columbia. Although only three species are recorded from British Columbia, up to 25 proturan species might occur in the province (Cannings and Scudder 2001).

These are very minute, slender, mostly unpigmented apterous hexapods with entognathous mouthparts. The prognathous, pointed head lacks eyes and antennae, and there is no internal skeleton or tentorium in the head. However, the head laterally bears a pseudocellus on each side.

The legs are five-segmented, with a one-segmented tarsus and a single claw. The forelegs are longer than the other legs, are held forward in front of the head, and have a sensory "antennae-like" function. The abdomen of the adult is composed of 12 segments, with the first three segments ventrally bearing style at the posterior corners. There are no cerci.

Very little is known with regard to the ecology of the Protura (Tuxen 1964). Typically they are soil dwellers, and are usually associated with moist habitats. Elsewhere in the world they have also been found in leaf litter, moss and occasionally in decaying wood.

Although we know little about local species, typically proturans show little change in form as they grow, but they are well known for the fact that there is an increase in the number of segments in the abdomen as they pass through the immature instars. On hatching from the egg, the first instar has nine abdominal segments. The second instar has nine and the third instar then. The fourth, like the following two instars have 12 segments to the abdomen.

References

Cannings, R.A. and Scudder, G.G.E. 2001. An overview of systematic studies concerning the insect fauna of British Columbia. Journal of the Entomological Society of British Columbia 98:33-59.

Tuxen, S.L. 1964. The Protura. A revision of the species of the World with keys for determination. Hermann, Paris. 342 pp.