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.
In this paper are given the descriptions of two new species of the genus Pardosa C. KOCH found in Japan. These species resemble each other morphologically and ecologically, inhabiting riversides and seashores.
Five species of the spider genus Tmarus SIMON, 1875 are confirmed from Japan and Taiwan. Two of them, T. rimosus PAIK, 1973 and T. hanrasanensis PAIK, 1973, are new to the Japanese fauna. Two new species, T. yaginumai from Japan and T. taiwanus from Taiwan, are described. A Palaearctic species, T. piger (WALCKENAER, 1802), is compared with European specimens.
In this paper, the author deals with the review on the east asiatic millipede belonging to Riukiaria-Rhysolus-Rhysodesmus group. Several authorshave already commented that was next to impossible to make exact distinctions between Rhysodesmus and Riukiaria. The author discussed the generic status of Riukiaria in this paper. Then, all of east asiatic millipeds of this group, so called “Rhysodesmus”, are not classified to real Rhysodesmus, but most of them are belonging to the category of genus Riukiaria.
The author once made a report on the segmental structure of abdomen in Arachnura sp. _??_.Much attention has since then been paid to the abdominal structures of various spiders. The observation has revealed the following facts. 1. The spiders which still retain comparatively distinct traces of segmental structures after becoming adults are Oxytate and Misumenops. 2. Even in other spiders, the same structures can be seen in the early stage of post embryonic development. The following is the report on these findings.
1. A comparative anatomy of some internal organs in nine spicies of Trionycha is reported on the basis of female adult specimens collected in Tottori Prefecture. 2. The ratio of the length of book-lung to body length is nearly constant throughout the nine species. 3. The tracheal system was observed to differ in structure from one another in seven of the species studied. 4. With respect to the seven species in which the diverticula of thoracenteron were studied, the lateral diverticula are disposed in accordance with the legs. 5. There are three spermathecae in Tetragnatha praedonia L. KOCH, while two exist in the other eight species. 6. The pyriform glands are sausage-shaped in Uroctea compactilis L. KOCH, but they are typically pyriform to elliptical in the other eight species. 7. The aciniform glands were recognized to be absent in Meta yunohamensis BÖS. et STR., Leucauge magnifica YAGINUMA and Tetragnatha praedonia L. KOCH. These glands of Agelena limbata THORELL are modified-cucumber-shaped, whilst those of the remaining four species are typically like a cluster of grapes. 8. The tubular glands considerably differ in shape from one another in six of the species studied.
External genital organs and genital suckers of Tyrophagus dimidiatus were studied by using the scanning electron microscope. The female has two genital openings, one is the gonopore and the other is the copulatory orifice. The copulatory opening is situated behind the anus, which measured about 5μ in diameter. Near the opening there are several short spines measuring about 0.5μ in length. The male has a penis. It is S-shaped, and is measured about 25μ in length. The tip of the penis measures about 1μ in diameter and the elliptical base has diameters of about 5×10μ. Both sexes have two pairs of genital suckers, which are found near the external genital organ. They are not used for copulation, when the internal pressure of the body fluid is raised, in males, the tips of these organs may be extended on both sides of the genital organ.
Six stages of breeding for the embryos and larvae in Garypus japonicus were described in order. The breeding phenomenon was studied anatomically and histologically from the viewpoint of a nutritive connection between the mother and the embryos or larvae. The nutritive connection seemed to consist of three processes, viz. the secretion of the nutritive fluid from the ovarian epithelial cells into the ovarian lumen, the transportation of the fluid from the lumen into the brood sac, and the ingestion of the fluid by the embryos and larvae in the brood sac. Although these three processes progressed in different sites and by different manners, some functional and periodical correspondences were found both between the secretory and the transportating processes and between the transportating and the ingesting processes. Hence, the transportating process was regarded as connecting functionally and periodically the other two processes and effectuating the nutritive connection in G. japonicus. Based mainly on these orrespondences, the six stages of breeding were able to be established.
It is frequently observed that Silerella vittata (KARSCH) plunders ants of the eggs, larvae and other things which are carried, and on this behaviour a short report was already given by Jo (1964). But this habit does not seem to be limited to S. vittata, for several salticid spiders (Menemerus confusus, Plexippus setipes, Evarcha albaria) were observed to show the same behaviour, though less frequently. In this report these observations, except for the case of S. vittata, are described in detail.
The social behavior of D. foliicola, a common spider in Japan, was investigated. D. foliicola was observed not only on plant leaves, but also in the artificial environments such as window frames and roadside guardrails. The spiders inhabited bathroom window frames weakly clumped. Similarly, female spiders were nearly clumped in the population on guardrails. It suggests that a strong gregariousness occurs among the female individuals. However, the males showed uniform distribution. The distances among individuals are quite close to about 1 or 2mm. The web of this species has two components, i.e. (1) an irregular web of hackled band threads for snaring insects and (2) a retreat of thin threads. In conclusion, the abundance of insects trapped by fluorescent light cause each spider population of window frames and of roadside guardrails to make a considerable gregariousness.
This paper gives ecological studies on cave spiders in Central and Southern Kyushu. The author surveyed the natural environment, spider fauna and seasonal fluctuation of Cicurina sp. in Katano-do Cave (Shibushi-cho, Kagoshima Pref.). As for the diural changes in summer (July 12-13, 1975), the daily temperature fluctuation was constantly 22±0.50°C at 60m inside the cave, and the humidity was constantly about 95% (cf. Fig. 1). Theridion tepidariorum, Theridion ferrumequinum, Coelotes sp., Falciletoneta sp. and Cicurina sp. inhabit in Katano-do Cave. Among them Cicurina sp. is the dominant species in Katano-do Cave and the density of 3 individuals per 0.06 m2 was shown. As for the seasonal flucutuations, females and larvae emerge throughout the year. Subadult males emerge from June to September. Adult males emerge from August to December.
Experiments were carried out to determine the predatory ability of spiders for 1st and 2nd instar larvae of the pine moth, Dendrolimus spectabilis BUTLER. HOLLING's (1959) ‘disc equation’ and WATT's (1959) equation were used in order to estimate abilities of spiders. The predatory ability of larger spiders, except the grass spider males, for 1st instar larvae was superior to that of smaller ones. Generally, spider males seem to be inferior to females and old nymphs as predators. The number of the 2nd instar larvae preyed upon by one spider decreased to about half of that in the case of the 1st instar larvae. It is concluded that the prey size is an important factor for the predation process.
Population density of spiders investigated in a paddy field in Kyoto City from May to November in 1975. Micryphantidae and Lycosidae were dominant in the paddy field and levee. Spider population in the paddy field showed 2 peaks in mid August and in mid October; particularly, it amounted to 200 individuals per m2 in mid October. On the levee, it showed a sawteeth-like curve with 3 peaks, amounting to 140 individuals per m2 in mid July and in mid October. Similarity of spider fauna between the paddy field and the in cultural period of rice crop was about 60%. In the consequence of examination on the larval percentage of dominant species, it seemed that the spiders passed the winter in the form of adult in Micryphantidae (=Erigonidae) and in the form of larva in Lycosidae. Oedothorax insecticeps has two generations in a year (TANAKA, 1973); a large number of the adult occur in early July and in early November. In the stage of adult and of subadult, female population appeared abundantly from June to July and from October to November.
Several authors pointed out that different spider species select different scaffolds. For example, ENDERS (1974) stated that two species of the genus Argiope coexist by selecting different scaffolds. But the kind and the quantity of preys caught by each spider species have not been investigated at the place where several species coexist. So the author analyzed the ecological distribution of each species in relation to prey distribution and the condition of scaffolds; then he investigated the quantity of preys caught by each species at various sites selected by spiders, and analyzed the conditions of coexistence of several species. Four spider species investigated inhabit sympatrically at stream side. Meta kompirensis and Tetragnatha spp. (T. praedonia and T. japonica) weave only at the space above the stream, but Leucauge agnifica weaves both at the space above the stream and among plants on the bank. Meta makes the largest web and Leucauge makes the smallest one, so Meta weaves mainly at the place with lower coverage and Leucauge with higher coverage, but Tetragnatha weaves both at places of lower and higher coverage. Prey insects are caught mainly by the webs above the stream, especially at the place where Meta and Tetragnatha weave frequently. It seems that Tetragnatha concentrates on such a place because of prey abundance, for this species abandons unproductive webs and weaves at another place. The concentration of Meta is not due to prey abundance, but due to the good condition for weaving. Leucauge can not weave at such a place because it's small web can not be made there owing to poor scaffolds. The interferences among spiders change the web distribution of each species also. Inter ferences shorten the web-keeping time of each species, especially of subordinate species (Leucauge and Tetragnatha) and subordinate individuals (smaller individuals). But many insects are caught at places where interferences occur frequently, so the number of insects caught by spiders is larger there than at the place where interferences occur rarely. Therefore subordinate species (or individuals) can coexist with dominant species (or individuals) if the latter does not keep the resource exclusively at the place where prey insects are abundant.
The weaving spiders live by making their webs according to their own weaving mode. The weaving mode consists of web form, web size, web angle, web height, web thread character, etc., and it is generally similar within a species, a genus or a family. The basic weaving modes are as follow: vertical (both single layer and multi-layer), horizontal (both small and large), cubic (both true cubic and line), sheet (inverted dish, with or without cradle; saucer, with or without cradle), and fixed (flat and curved surface) (See table 1). But the basic mode may be modified by situations such as growth and developmental stage, or slight individual variations, etc.. In the classification of the spider's webs only their shapes have been noticed. This paper suggests a modification of this classfication by adding the important factors of the spatial Orientation and the spatial surrounding micro-habitat to which the web is attached. Web of any types are attached to some objects (such as tree branches or windowframes); these objects form scaffolding stands which have several possible characters: form, size. mobility, condition of surface, etc.. There are several shape types of scaffolding stand as follows: lengthwise, box with ceiling, widthwise with ceiling, widthwise with underbase, flat surface (See Fig. 1). On the other hand, from the viewpoint of weaving condition the surface of the earth has several types of habitat (Table 3). And each habitat consists of various micro-habitats. For example, a forest consists of 4 micro-habitats as follows: open area among trees, peripheral foliage, central foliage, basal area (soil, trunk, lowest branches, and open space) (See Fig. 2). such micro-habitats offer the scaffolding stands for making webs. These scaffolding stands, along with the shape and spatial orientation of webs themselves make up the weaving environment of the weaving spiders.
Yamanashi Prefecture is situated in the middle of Honshu, and is one of the mountainous prefectures in Japan, with Mt. Fuji, South Japan Alps, Mts. Yatsugatake, Mts. Oku-Chichibu, Mt. Daibosatsu, and others. The author, in this paper, gives a short historical review of the studies of Araneae in Yamanashi Prefecture, accompanied with a list of 39 articles, including the local publications, published in Japan untill today.
In 1969 and 1970 I published the papers entitled “Spiders of Tokyo I and II, ” which contained 355 species belonging to 37 families of spiders from Tokyo (including the Izu islands and the Bonin islands). The present paper deals with brief descriptions of 47 species of spiders which are newly added to the spider-fauna of Tokyo. These records are based on numerous published and unpublished sources, and include some records which are at present in press. Of 47 species listed in the present paper, including the records in the literature, one species (Erigonidiumnigriterminorum) is from Mikurajima island, 2 species (Coleosoma blandum, Argiope key-serlingi) are from Aogashima island, and 3 species (Smeringopus pallidus, Cyclosa camelodes, Lycosa matushitai) are from the Bonin islands. With these additions, the spiders in Tokyo number 402 species in all.