Art. XIII.—Note on the Occurrence of Metoponorthus pruinosus, Brandt, in New Zealand.
[Read before the Philosophical Institute of Canterbury, 7th June, 1905.]
In the list of Crustacea in the British Museum published in 1847, a species, Porcellio zealandicus, is named but not described (p. 99). It remained undescribed till 1876, when Miers, in preparing a catalogue of the New Zealand Crustacea, examined all the New Zealand Crustacea in the collections of the British Museum and described those he considered new. His description of Porcellio zealandicus appeared first in the “Annals and Magazine of Natural History” (ser. 4), xvii, p. 225, and was also given in the “Catalogue of New Zealand Crustacea,” and was there illustrated by two figures.
In the “Crustacea Isopoda Terrestria,” published in 1885, Budde-Lund put down the species as a doubtful synonym of Metoponorthus pruinosus, Brandt. Up to that time, and for long afterwards, no local collector had recognised the species; and in my “Terrestrial Isopoda of New Zealand”* I could only add to the account given above that I had examined the type specimen in the British Museum, and that it was undoubtedly a Metoponorthus, and apparently closely resembled M. pruinosus, though the condition of the specimen was not sufficiently good to allow one to be quite sure on this point. I also pointed out that, while it would not be extraordinary if this cosmopolitan species were found in New Zealand, still it was not known to local collectors up to that time; though, as the British Museum specimen must have been obtained before 1847,† we might have imagined that the species, if really existing in New Zealand at that time, would have since become abundant.
In 1901 I recognised numerous specimens of Metoponorthus pruinosus among Isopoda sent from Norfolk Island, but none from New Zealand till March, 1905, when among some Crustacea sent me by Mr. Hutchinson from the shores of a tidal lagoon in Hawke's Bay I found numerous specimens of this species. I have compared them with the Norfolk Island specimens, and also with specimens gathered in England, and find that they are all specifically identical.
[Footnote] * Trans. Lunn. Soc., 2nd er., Zool., viii, p. 141.
[Footnote] † Since this was written Dr. T. W. Calman, of the British Museum, informs me that it is not quite correct. The specimens recorded by White in 1847 were from “Van Diemen's Land”; that from New Zealand, described by Miers, was received by the Museum in 1854.
There is therefore no longer any reason for doubting that this widespread species had established itself in New Zealand even before 1854. It is interesting to note, however, that it does not appear to have spread widely in New Zealand. I have certainly never seen it in the South Island, where I have collected pretty widely for many years past; and, though I have not personally collected it in the North Island except near Wellington, I have had many terrestrial isopods sent me from different places in that Island, but no Metoponorthus pruinosus till I got those sent by Mr. Hutchinson.
The same thing is true of another introduced species, Armadillidium vulgare, Latr., which is common in the City of Nelson, but has so far not been recorded from any other part of New Zealand except Mount Egmont, whence a single specimen was sent me years ago by the late Mr. Drew. On the other hand, Porcellio scaber, Latr., another introduced species, is extremely common all over New Zealand, and, in addition to being found near inhabitated places, has penetrated to some extent into the bush far from houses.