Diptera) and the Problem of the Pacific Island Fauna

New Zealand Cyrtidae (Diptera) and the Problem of the Pacific Island Fauna. S.]. PARAMONOV1 DURING THE PREPARATION of a review of The author has had an opportunity to study the Australian Cyrtidae some New Zealand some specimens of Apsona muscaria West material was used for comparison. The study wood, the only species of the genus if we do of this material has shown that a review of not include Apsona caerulea Brunetti from New Zealand cyrtids is also required. For the Brazil. (Brunetti has not compared his species clarification of some systematic problems the with Eulonchus and it is difficult to tell to author was forced to collect all available in which genus the Brazilian species belongs.) formation about New Zealand cyrtids, and He has found an astonishing similarity be to write a short, preliminary review of them. tween muscaria and Eulonchus smaragdinus The publication of this review, the author Gerst. from California. The size, shape, col thinks, will be useful for New Zealand dip our, structure of integument, venation, hairs, terists. The author quotes the descriptions in and many other characters are so similar that extenso, because they are dispersed mostly in they can almost be regarded as belonging to old, not very easily accessible publications the same species. Only detailed study under and it will facilitate the undertaking ofa more a lens (see below) shows that they are differ extensive study of New Zealand members of ent, but the generic difference between them the family. is in doubt. Comparison of the fauna of cyrtids of New A comparison of all Apsona and Eulonchus Zealand and Australia has given material for species will doubtlessly show that Apsona mus some general conclusions, which can be used caria Westw. and Eulonchus smaragdinus Gerst. in solving the problem of the Pacific fauna. are remarkably close or possibly congeneric. The representation of Cyrtidae in New Zea Lack of material does not permit the author land is very poor: 1 species of Apsona, 3 spe to state that the two genera are synonymous, cies of Helle, and 3 species of Oncodes, but there is no doubt about their very close representing three different subfamilies, but relationship. The species of the complex Eu it has some significance in the problem ofthe lonchus-Apsona are distributed in New Zealand, origin of the Pacific fauna. North America and South America, but are To the present time representatives of the quite absent from Australia. genera Apsona (Panopinae) and Helle (Phil The genus Helle is comparatively very well opotinae) are not known in Australia and represented in New Zealand (three species), there is no reason to believe that they will be whereas no representatives of the whole sub found here in the future. family Philopotinae are recorded for Australia. Elsewhere the distribution of the subfamily 1 Division of Entomology, Commonwealth Scien tific and Industrial Research Organization, Canberra, is confined to widely separated areas. In Amer A.C.T. Australia. Manuscript received June 28, 1954. ica the genus Helle is absent, but Philopota, a 16 New Zealand Cyrtidae-PARAMoNov 17 closely related genus, is present. The causes ofthis destruction were various: The genus Oncodes is cosmopolitan, but 1) some elements adapted to the arid area none of the species has been found to occur conditions were eliminated by the absence in both in Australia and New Zealand. New Zealand of deserts and by very high Thus the information we have on the New humidity, 2) some elements were destroyed Zealand Cyrtidae would indicate a closer re by the glaciation, which was not very intense, lationship, with respect to their origins, be but which changed fundamentally the ecolo tween the New Zealand and American fauna gical conditions. than between the New Zealand and Aus When the author was writing his Review of tralian. Australian Apioceridae (Paramonov, 1953), he Let us now examine the general features of was restricted by the scope of the theme and the dipterous fauna of New Zealand. First could not discuss the problem of the absence the absence, or extremely poor representation, of the family in New Zealand; now it will be of some families must be recorded: Neme useful to express his ideas in a more extensive strinidae, Apioceridae, Scenopinidae, Mydaidae, form. Conopidae are quite absent; some large families, If we accept the destruction of apiocerids such as Bombyliidae, Leptidae, are represented by glaciation, we must examine theoretically by one species each. What is the cause of this the three following alternatives. absence? It is quite evident that all these and 1. A large continent (for example, Australia similar elements of the fauna were present in or South America) is undergoing glaciation. :New Zealand in different geological periods. Will the result of glaciation be the destruc During its geological history New Zealand tion of the fauna of the continent? Most has been repeatedly covered by the sea, but probably not, because the continent extends since mesosoic time it has been definitely from north to south for a very great distance. above the sea and part of a large continent, We cannot suppose glaciation to cover the which was situated mainly westwards of the whole continent. On one or the other end present position of New Zealand. Australia of it there will exist much more mild climatic is also a part of this earlier continent. conditions, which will permit the existence of In Trias-Jura time New Zealand was more the different elements of the fauna. Such extensive, reaching to New Caledonia or even glaciation cannot wipe out the fauna-the farther northwards, eastwards reaching the animals will only migrate to the warmer areas Chatham Islands and southwards to the or strips of land or "pockets." Campbell Islands. If we suppose the whole of the state of The main ranges ofmountains were created Victoria, from the Kosciusco summit to sea during the Pliocene. The uplift was continued level to be covered with snow and ice, we in the Pleistocene. This was the time of the can be sure that in the area of Cape York greatest glaciation. The end ofthe Pleistocene there will be areas serving as "refugiums" for was a time ofsubsidence when the sea coveted the different elements ofthe fauna. Never will the sea-shore zone to a height of 40-150 the fauna be completely extinct. After the end meters above present sea level. This subsidence of glaciation the animals will migrate back -changed to slow uprising which has continued. into Victoria. The glaciation can cause max Thus New Zealand has been connected imally only the impoverishment of the fauna with land-masses which have representatives and temporarily the change of its spatial dis ofthe above mentioned families in great num tribution. ber, and such families were destroyed during 2. We will have a quite different picture if the process of New Zealand's isolation. the glaciation covers a not very large island 18 PACIFIC SCIENCE, Vol. IX, January, 1955 (for example Tasmania) and is strong and the coexistence of a huge mass of ice and, prolonged-the extinction of the fauna will at a distance of 2-3 hundred metres, a huge, very probably occur. However, if the island very tall forest. Here we have equilibrium is part of a long chain of islands, there is a between the elements causing the glaciation good chance of reimmigration after the end and deglaciation, and this equilibrium has of glaciation. existed for at least 100-200 years because the 3. If we have some large islands with their forest near the masses of ice has required such axis in a north-south direction, and these time for growth. islands are isolated by very broad ocean areas However, there is another type ofmeteoro from all continents and islands (e.g., New logical combination which can destroy the Zealand), the extinction or impoverishment essential parts of the fauna without glaciation of the fauna during strong glaciation is very -the periodical or permanent lowering ofthe probable. temperature in the winter. Itis enough to have From these explanations, I think, it is evi 5-10-25 years of winters with the tempera dent that the comparison of New Zealand tures under 0° c., and all the insect pupae in with Australia or South America is not well the superficial layer of the soil will be frozen. grounded. The general wnditions are very The apiocerids are a very old group from very different. In New Zealand there is not the warm countries. They have not developed possibility of reimmigration of the fauna. adaptations to cold winters, their pupae al Let us now consider the glaciation. In Aus ways lie shallowly in the soil. A number of tralia there never was a glaciation which cov winters with temperatures under 0° C. can ered extensive landmasses as by a shield. The cause the complete extinction of the apiocer glaciation touched only the mountain area ids. It will be useful to remember that in and as a result no complete fauna or even the Siberia (Yakutsk area) in the coldest point of outstanding elements of parts of that fauna the whole world (the temperature in the were destroyed. There was only temporary winter drops to - 70° C.) the snowfall is very redistribution of the elements of the fauna small, usually so small that horses can find in space. food under the snow during the whole winter. I think we have a similar condition also in In such a way we can explain the extinction New Zealand, where the glaciation was never of apiocerids in New Zealand, not only di so strong as to be able to destroy the whole rectly by strong glaciation but also by a series fauna.

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