The Black-rumped Spider is Here - At Last

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when, through the assistance of the Swedish consulate and embassy in Beijing, I was able to clarify to the higher police authorities that they had seized my camera in a manner that could not be called officially correct. I subsequently received only the camera back. Unfortunately, species determinations are difficult afterwards since many of the genera are species-rich and I hope the reader will be forgiving of this.

A trip to China can nonetheless be recommended, and I was exceptionally unlucky in encountering a woman who had been involved previously when butterfly collectors were arrested. My impression was that no one would think of going to the police if they could not profit economically from the matter. Butterfly collecting is permitted for Chinese nationals, and in Beijing there are shops that sell butterflies and other natural history specimens. The prohibition applies only to foreigners and should be seen as a manifestation of the commercial opportunism one becomes very quickly acquainted with in all aspects of life.

THE BLACK-RUMPED SPIDER IS HERE—AT LAST

In the journal Fauna and Flora of the Naturhistoriska riksmuseet, in its final issue for 1996, the senior curator Torbjörn Kronestedt writes that the black-rumped spider has now been found in Sweden as well. We have indeed had to wait a long time for it. Several specimens of both males and females were discovered in the Bergianska Garden's greenhouse, which is adjacent to the Naturhistoriska riksmuseet. They have probably been there for quite some time.

The black-rumped spider presumably originates from the southern hemisphere. Since then it has had an incredible ability to spread over large parts of the northern hemisphere. The dispersal has partly presumably occurred with human assistance and partly through the kind of wind-borne flight common to spiders.

The first description of the black-rumped spider dates from 1879 when it was found in New Zealand. During the latter part of the 1890s this species was collected during Otto Nordenskjöld's and Erland Nordenskjöld's respective expeditions to the Magellanic Territory in southeastern Chile. In the years that followed, the black-rumped spider was found in Argentina, Brazil, Peru, on the southeasternmost Tubuai Islands in the Pacific Ocean, on Hawaii, in Australia, Japan, on the small French volcanic islands of Amsterdam and St. Paul in the southern Indian Ocean, on the Atlantic islands of St. Helena, the Azores, the Canary Islands and Madeira. In Africa it has been found in several locations from South to North Africa, including on high mountains such as Mount Elgon, Mount Kenya, Mount Meru and the Cameroon Mountains.

Then the black-rumped spider began to be found in Europe both in greenhouses and outdoors. In the latter case mostly in waste places, among refuse and in compost heaps. The first European find was made in England in 1906. It had presumably arrived there by ship. Not until 1937 did it appear on the continent for the first time. It was in Portugal. Also a maritime nation. During the war it was discovered in France in 1944. In Germany it was found in 1957 near Hamburg.

Already in 1975 the first specimens were found in the Nordic region. And they even lived outdoors. They were discovered in Finland in the Helsinki area. These black-rumped spiders would probably not have been discovered had someone not thought to conduct a faunal survey of a compost heap and various soils composed of waste sludge and bark.

The first find from Poland was reported in 1979. In Slovakia it was first found in 1990. It has also been discovered in Switzerland, Czechia, Austria and the Carpathians where they have been found at high elevations. In the Alps near Innsbruck they have been caught in pitfall traps at 2200 meters elevation. In the Tatra Mountains in the Carpathians finds have been made at 1750 meters elevation. Much of this dispersal in Europe must reasonably have occurred through wind-borne flight.

The black-rumped spider Ostearius melanopygius must now be counted as one of the most widespread spider species in the world. It has long been expected in Sweden. However, no Swedish finds have previously been reported.

The black-rumped spider belongs to the spider family Linyphiidae (sheet-weavers and dwarf spiders). It is a small spider no longer than two and a half millimeters as an adult. The spider has acquired its unusual name from its appearance. The female is light brown-red with a black area at the rear around the spinnerets. It also has a black spot at the genital opening on the front part of the underside of the abdomen. The cephalothorax can be more or less dark brown. The Latin species name melanopygius derives from Greek melas, which means black, and pyge, which means rear end. So the newly coined Swedish name black-rumped spider is indeed apt.

Gunnar Backen, Barrvägen 1, Gävle

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