Arachnologically

The district of Hanover, he said, and indeed, practically, the whole high Karoo plateau, was unexplored arachnologically;

Source: wiktionary

Arachnologically Filey is almost terra incognita.

Source: wiktionary

The following Monograph gives an account of the Drassid spiders of South Africa. The term South Africa is meant to apply to the region south of the 15° latitude and not to political South Africa. Even so, the boundary is an artificial one arachnologically, for, as far as can be seen from the distribution of the species at present known, certain Cape Province species occur in South-West Africa, and others spread northwards to the East African equatorial region, and certain Abyssinian species spread south to the same region.

Source: wiktionary

It would be natural to compare at first the spider faunas of Newfoundland and Labrador, but unfortunately this part of Canada is very little known arachnologically.[…]The areas compared are, of course, of different size and studied arachnologically in different degrees.

Source: wiktionary