| Research Abstract |
The aim of this study was to clear a mystery, how did the Mesothelae spiders have survived from the Devonian Period to the Recent. A systematic study of spiders of the suborder Mesothelae (Araneae) including information of Paleozoic fossils was carried out as follows.
1) Research trips were made between 2004 and 2006 mainly in southern Kyushu, Tanegashima and Yakushima Islands, and Amami Islands, southern Japan, and many specimens of both Methothelae and Opisthothelae and their ecological data were collected in selected forests from lowlands near seaside to preserved mountainous forests with various collecting methods. Travel expenses were used for the researches.
2) Other than these specimens, existent materials of Ryukyu Islands of Japan and those from East Asian countries were studied in the laboratory of the National Museum of Nature and Science, Tokyo, by morphological and anatomical methods including observation with electron microscope. For these operations, budget was shared for part-time job for assistants and consumption articles.
3) On the basis of discussions with scientists of museums and universities not only of Japan but also of foreign countries as England, Germany, Australia, and China, several papers with descriptions of new species were published since 2004. About 90 species described under the family Liphistiidae include 40 heptathelines and 50 liphistiines, all from East Asia. The former subfamily is distributed in the northeastern part of Southeast Asia, including Southwest Japan, China and Vietnam, while the latter ranges in the southwestern part with eastern Burma, Thailand, the Peninsular Malaysia and Sumatra. At the first sight both the distributional ranges are separated without overlapping each other by the Mekong valley. Although information from Laos and Cambodia is lacking, some suppositions on possible origin of this allopatry were presented at the International Congress of Arachnology held in 2007 at Sao Paulo, Brazil.
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