昭 和31年(1956)12月 361

Scorpions of Micronesia

Haruo TAKASHIMA

The area which is stated as Micronesia hereafter had been under Japanese mandate until the end of the World War II. The is an group, making an order in Arachnida, and in Japan, it has been feared as poisonous animal since the ancient times. On this scorpion in Micronesia, Prof. Teiso Esaki wrote an article called "Scor- pions in Micronesia" in December, 1943, and in it, he enumerates the spotted house scorpion Isometrus europaeus and the wood scorpion australasiae. Al- though I have never made a trip to Micronesia, I have been able by the favours of many people, to get a considerable number of scorpion's specimens to examine them. I knew, through those specimens and many other literature, that there were only these two species in existence, and no other species could be added. Moreover, even these two species are considered that they were not originally in Micronesia, but were brought from some other area. On the contrary, and to my great surprise, I found in the German academy gazette "Sen- ckenbergiana" Vol. 26, No. 4, which happened to be published about the same time as of Prof. Esaki's, December, 1943, and where C. F. Roewer made an identifica- tion report on the specimens of scorpion kept in the Natural History Museum in Senckenberg, that a new species of the scorpion, male, produced in Micronesia-although strictly the locality was Saipan Island-was introduced by him. Namely, it is Urodacus marianus. Although I have never examined them direct but only by photos and sketches, I know this scorpion

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Urodacus is endemic in and there are about 19 species in the genus. I have been interested in this genus by chance, but I have never expected that it would be a new species. Prof. Esaki told me that it might have been introduced from Australia when Micronesia had been under German sovereignty once and had communication with Australia, and only they had not been noticed by the student. Roewer states nothing about its history, and as regards the material, there is only one male, as holotype specimen available. Its length of carapace and fore- abdomen is 25mm. and is 37mm. in the length of tail, and it can be definitely re- cognized from the other two species. The three species can be recognized as follows.

A Sternum triangular, become narrow in front. Lateral eyes 3 on each side. Pectinal

teeth 17-19 (usually 18)…Isometrus europaeus

AA Sternum strikingly pentagonal.

B Lateral eyes 3 on each side. Pectinal teeth 4-8 (usually 6)…Liocheles australasiae

BB Lateral eyes 2 on each side. Pectinal teeth 14…Urodacus marianus

I shall not go to Micronesia in the future, and even if there be a chance, I shall have to excuse myself from it, because I am not in healthy condition. And the main purpose of writing this is that I wish to draw the attention of the students of this group especially to the 3rd scorpion.

Isometrus europaeus (Linne) Scorpio europaeus Linne Syst. Nat. ed. 10, p. 625 (1758) Isometrus europaeus Lonnberg, Ann. Nat. Hist. ser. 7, vol. i, p. 86 (1897)

The spotted house scorpion is called so, since it had many dark-brown dots on its trunk, tail, chela and legs. The Oriental region seems to be its area of origin and have spread over the tropical and sub-tropical area of Asia, Africa and America with the shipments on board, and at present, the species is a cosmopolitan in the above areas. In the year of 1951, I got six of this species which had been found in the property sent to the American forces, and have fed them. You may understand that europaeus will possibly break a new ground this way, and while I suppose that those six were not the only ones that were brought to Japan after the war, it will be impossible for them to settle in Japan. This species which began to settle and increase in Bonin Islands had been originally in the banana-baskets which came from somewhere around Saipan. In Micronesia, it seems to be in the comparatively dry places, either outdoors or indoors, and the one which happens to come into the house sometimes hurts us. Fortunately, however, its poison is not strong, and even in case it hurts our fingers, it does not hurt so much as when stung by a bee, and it is said that it can be cured only by packing the hurt with a towel soaked with warm water. This species also hides itself in the gloomy places such as water closet, and you have to be careful.

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Liocheles australasiae Scorpio australasiae Fabricius, Syst. Ent., p. 399 (1775) Liocheles australasiae Simon, J. Asiat. Soc. Bengal vol. lvi, p. 113 (1887) Liocheles australasiae is called "Yayeyama Sasori" in Japanese which means the scorpion in Yayeyama, as it inhabits in Yayeyama Group, Ryukyu Islands. In fact, however, this species is spread over the areas, zoogeographically called Oriental region and Australian region, and is great in number. In Ryukyu, it is found only in Yayeyama Islands, and it is also found in Formosa, Botel Tobago Islands, and South up to Central China. The fore-mentioned Isometrus europaeus, too, is found only in the area represented by Miyako Group and Yayeyama Group, and can not be seen in Okinawa Main island and Amami Group. Therefore, it can be said that any of the species does not exist in Japan at present. This species is said to be outdoors in Micronesia and never comes indoors, hiding himself in the gloomy, damp places such as under the skin of tree. It is also said that its poison is weaker than that of Isometrus europaeus, and Prof. Esaki has seen the inhabitants of the island picking them up with their fingers. Moreover, it is safer, as it does not come indoors. In general, its female is 3.5cm. in average length, while a much longer one, 5cm. long or so is sometimes found. The secondary sexual character is recog- nized on its genital operculum, etc., however, it is not very evident. On the other hand, Isometrus europaeus shows, as you know, a very evident secondary sexual character. It is known some of the scorpions, although not so many, have fatal poison, but it is fortunate that the two species in Micronesia are not with such strong poison. Its expiration and prevention is supposed to be rather easy. This Liocheles australa- siae had been with Lauan lumbers from Borneo and found in the lumber-pool in Nagoya early in Octover, 1955, and it was reported in the newspaper as an unusual happening. This species also seems to come to Japan this way. In conclution, there are only three species of scorpions in Micronesia and, one of them, Urodacus marianus will further have to be examined by collecting them in the future, and I. europaeus and L. australasiae are not necessarily suitable materials for discussing the animal distribution, as stated above. The scorpions are, therefore, cannot be said to be the animal group wich gives a special character to the Micronesian fauna.

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