Art. LXXII.—On a New Species of Ant from New Zealand.
[Read before the Wellington Philosophical Society, 20th February, 1895.]
The Formicidae of New Zealand are of high zoological interest. We may regard the actual fauna as a relic from an old Australian fauna that remained there unmixed and safe from Indian immigrations which took place on the Australian continent, but was badly disseminated by partial submersions and by the rigorous climate of the glacial epoch. Evidence of the great influence of the Ice Age may be assumed from the fact that the most characteristic Formicidae of New Zealand (and, as Mr. W. W. Smith informs me, the termites) are found only on the North Island; very few species of ants are found living on the South Island, and none peculiar to it. I therefore think that the glacial climate destroyed all the ants and termites on the South Island, Later a few of the most diffusible species (Monomorium, Huberia, Lasius) wandered across the sea towards the south.
In 1892 my friend Professor Forel published* a list of the New Zealand Formicidae, and described some new species. Since that year a few more have been discovered. Professor Forel has lately described Monomorium integrum; while two other species, a Ponera and a Huberia, will shortly be desribed by him.
The only known ant from New Zealand not seen by Forel was Orectognathus perplexus, Sm. I suspected it to be identical with Strumigenys antarctica, Forel, and that Smith had wrongly counted the number of joints of the antennae. Mr. W. F. Kirby did me the kindness to examine the type in the collection of the British Museum, and found that the antennae are 6-jointed. The insect belongs therefore to the
[Footnote] * “Die Ameisen Neu-Seelands,” in Mitth. Schweiz. entom. Ges., Bd. 8.
genus Strumigenys, and will henceforth be named S. perplexa; S. antarctica, Forel, being a synonym of it.
I describe here a new species belonging to the genus Discothyrea, which was established by Roger in 1863 for one species from North America. The occurrence of this genus in New Zealand is a further evidence of the cosmopolitanism and great antiquity of most genera of Ponerinae.
Discothyrea antarctica, n. sp.
♀. Testacea, subtilissime punctata et tenuissime pubescens, pilis erectis omnino destituta, thorace superne convexo, haud marginato, metanoti pagina declivi subplana, marginata, superne minute, obtuse bidentata. Long., 2mm.
Found on Hunua Range, January 26, 1891, by Captain Broun, and sent by Mr. W. W. Smith. Three specimens.
The New Zealand species differs from the North American mainly by the laterally non-marginated thorax and the greater size. Roger's description is too incomplete to allow further comparison. I give an outline of the insect viewed from the side.
In respect to the generic characters, if we compare Discothyrea with the allied genus Proceratium, we must admit that the clypeus is reduced to form only the sharp edge of the disk-like produced forehead, the part which in other genera is wedged between the laminae frontales being totally atrophied and the latter coalesced. The mandibles are triangular, with a concave, toothless inner edge terminated by a sharp point.