Acta Arachnologica
Online ISSN : 1880-7852
Print ISSN : 0001-5202
ISSN-L : 0001-5202
Spiders from limestone caves of Akiyoshi-dai plateau, Yamaguchi Prefecture, Japan (II)
Takeo YAGINUMA
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1977 Volume 27 Issue Specialnumber Pages 1-21

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Abstract

This is a continuation of my previous paper. (1936) on the cave spiders of the Akiyoshi limestone area. Total 57 species are now recorded from the caves of this area, and 32 of them have been found by later investigations. Of these, two are new to science, a Coelotes and a subspecies of Nesticus akiyoshiensis. Only six species, or 10.7% of the known spiders, seem to be peculiar to Akiyoshi caves. They are: Leptoneta akiyoshiensis, Leptoneta kuramotoi, Leptoneta uenoi, Nesticus akiyoshiensis (with subsp. ofuku), Cybaeus kuramotoi and C. okafujii. Most of the nineteen species that are regarded as troglophilous and scotophilous forms are common to caves in other areas.
It is interesting that in spiders, the degree of adaptation to old caves in the Akiyoshi limestones is roughly comparable with that to new caves in the Fuji lavas. In both the areas, troglobiontic species are relatively few in number and the endemicity to individual caves is low. This cannot be attributed to a mere coincidence. The former suggests that the degree of adaptation is not dependent solely on the history of caves. The latter seems to indicate that the isolation between caves is not complete in the areas under consideration.
In one of my previous papers, I stated that no differentitaion of cave spiders may have occurred within the Akiyoshi limestone area. However, later investigations show that at least in Nesticus akiyoshiensis, decided morphological difference can be recognized between the populations of the eastern plateau and those of the western one, which are separated from each other by the valley of the River Koto. In this paper, therefore, I divided the species into two subspecies. A similar phenomenon has already been known in the trechid beetle, Trechiama pluto.

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