The Anatomy, Morphology and Habits of Pachyrhamma fascifer (Walker, 1869) (Orthoptera, Rhaphidophoridae)

Abstract

The purpose of this work is to investigate the anatomy, morphology and life history of a cave Orthopteran and correlate its behaviour and habitat with those of other members of the Gryllacridoidea both in New Zealand and other parts of the world. The anatomy and morphology of Pachyrhamma fascifer show it to be a typical hemimetabolous insect. The presence of muscles in the flagella of the antennae is of interest because as far as is known this has never before been recorded from among the Orthoptera. As intrinsic muscles of the antenna are known to occur in the Diplura, this forms a link with primitive insects, and through them with the myriapods. The presence of a median ocellus, the two lateral ones having disappeared, although vestigial nerves are still attached to the protocerebrum, shows the insect is in the process of adapting itself to meet the needs of its environment. Study of the behaviour of P. fascifer has shown it to be a highly sensitised insect sometimes found solitary, but more frequently in large numbers, throughout most of New Zealand. It is omnivorous in its diet, and cannibalism is known to occur, especially during the mating season. Comparison of the habits and habitat of P. fascifer with other members of the Rhaphidophoridae in various parts of the world has shown a great similarity, which is probably due to separate evolution along similar lines because of similar conditions, rather than close relationship. It was planned to make a detailed study of the life history, but all attempts to hatch the eggs in the laboratory were unsuccessful. It is thought the complete life cycle takes three years, but further information on this subject is still required. The eggs hatch in late July or August and the nymphs reach maturity in late December or early January, eighteen months later.