Art. X.—Notes on some Dragon-flies from the Kermadec Islands.
[Read before the Wellington Philosophical Society, 9th August, 1911]
In a small collection forwarded to me by Mr. A: Hamilton, of Wellington, New Zealand, five species are represented, four being species of wide distribution in the Australasian region, and the fifth (represented by a solitary female) probably a local race of a widely distributed oceanic genus of which the species and races have not yet been correctly worked out. They are the following.
1. Tramea sp., 1 ♀ (label No. 2).
Somewhat immature, and of pale coloration. The dark patch at the base of the hindwings is exceedingly small, and does not spread downwards into the anal areas of the wing. The male of the insect should be obtained, as from the form of the ♂ appendages and genitalia the species could be determined with certainty. I am of opinion that this will prove to be a local race of a widely distributed oceanic species. The genus is highly migratory, and one species is rapidly travelling down the east coast of Australia, and getting a strong hold there.
2. Hemicordulia australiae Rambur (label No. 3).
2 ♀, 2 ♂. In good condition, a dark and handsome form, practically identical in size and colouring with the specimens found in the Sydney district. This beautiful species, recognizable by the brilliant metallic-green
frontal patch on the head, and the sharp spine on the underside of the male appendages, has never before been recorded outside Australia. It ranges from Victoria, through New South Wales, to northern Queensland, but does not occur west of the main mountain-ranges. Its capture in the Kermadec Islands is therefore of considerable interest. The genus Hemicordulia is post-Miocene, so that the occurrence of this species may be taken as evidence of late land connection between Australia and the Kermadecs. The species is non-migratory, and does not occur in Tasmania, though exceedingly common on the northern shores of Bass Strait. The inference, therefore, is that the Kermadecs may have been united in some way, possibly via New Caledonia and Queensland, to Australia since the time (? Miocene) when Tasmania became separated. We should also expect, possibly, to find this species on Lord Howe and Norfolk Islands, whose Odonate fauna are still unknown.
3. Hemianax papuensis Burmeister (label No. 1, ♂).
1 ♀. Immature, but a fine specimen (appendages broken). Common all over New Guinea and Australia, except Tasmania, where it is absent. A strong flier, but not migratory. This reinforces the evidence of No. 2, Hemianax also being a Miocene or post-Miocene genus.
4. Aeschna brevistyla Rambur, 2 ♂ (label No. 1, ♀).
One specimen immature, one mature. This insect is found all over Australia, except in the most northern parts. It also occurs in Tasmania. In New Zealand a somewhat smaller and darker form occurs, which, though clearly conspecific with the Australian, may be distinguished at once from it by its abdomen being exceedingly pinched at the third segment, and its membranule very dark, with only a little white at the base. The Kermadec specimens are identical with the New Zealand form.
5. Ischnura aurora Brauer (= I. delicata Selys), (label No. 4).
5 ♂, 6 ♀. A very beautiful species, of wide distribution, ranging from the islands north of Australia, through Australia, to Tasmania. In Western Australia a dimorphic female, coloured like the male, occurs. The male has a bright-red abdomen shading to black, with a blue tip; the ordinary female is dull-blackish. These Kermadec specimens are practically identical with any series of this insect taken round Sydney.
In conclusion, therefore, this small collection shows the Kermadec Odonata to have a strong Australian element (three species out of five), a New Zealand element (one species), and an oceanic element (one species)