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From the foregoing it can be seen in what a muddle the systematics of the New Zealand representatives of the Macropathinae are in. The insects themselves are so variable within each species—particularly so in M. filifer which has the widest range of distribution and exhibits geographic as well as local variation—that it is difficult to find concrete characters on which to found either the species or the genus. It is primarily from this tendency towards variation—in some specimens I examined, the number of spines on the right and left legs of the same insect are different—that all the confusion in the systematics of the groups has arisen. New species have been named purely on differences in spination and, I feel, after examination of tables on the variability of the spines on the legs of over one hundred specimens, that I am justified in placing them all in the one species.
![Thumbnail: [Volume 82, 1954-55 page 755]](/journals/rsnz/images/rsnz_82/thumbnails/rsnz_82_03_0872_0755_ac_02.gif)
Another cause for confusion has been the failure to recognise the sexual dimorphism within each species. Apart from differences in spine counts P. novaeseelandiae, which is described from a female, is separated from P. speluncae, described from a male, by there being “no peculiarities in the antennae”. I have found that apart from the external genitalia, there is sexual dimorphism in the length of the legs and in the structure of the antennae within a species. Part of the cause for the large number of unnecessary species must be due to inaccuracy of description of the habitats of the specimens by the collectors, or lack of actual field collecting on the part of the worker. This seems to me the only way to account for males and females of the same species, collected from the same locality, and living together in such large numbers as Macropathus does in caves, being placed in separate species.
It appears to me that the most reliable character on which to erect the genus is the constancy in the number of the apical spines on the legs. This number never varies and yet for some unknown reason it was ignored by earlier workers in favour of less inflexible characters.
At the moment three species are placed in the genus Macropathus, but it is quite possible that there are others not yet recorded, or still waiting to be untangled from among those already described.