Siro LATREILLE 1796

SIRO LATREILLE, 1796

Diagnosis: The current composition of the genus does not provide clear distinctive features that would be specific to the genus within the family Sironidae.

Type species: Siro rubens Latreille, 1804.

Distribution: Parts of western and middle Europe, and North America. According to the current status this genus includes seven recent and one fossil species:

Siro rubens Latreille, 1804 – widely distributed in the south and south-east of France (Juberthie, 1991).

Siro valleorum Chemini, 1990 – slopes of the Alps in Lombardy (north Italy).

Siro crassus Novak & Giribet, 2006 – eastern parts of Slovenia.

Siro carpaticus Rafalski, 1956 – small areas in the northern Carpathian Mountains in Poland and Slovakia.

Siro acaroides (Ewing, 1923) – according to Shear (1980) this species is dispersed from northern California along the western coast of North America, slopes of the Coast Ranges, to the furthest northwestern parts of the state of Washington (almost the whole western coast of the USA). However, the validity of such a distribution is questionable. It is more likely that this is a distribution of a complex of species. A small portion of Shear’s material that I reviewed supports this assumption.

Siro exilis Hoffman, 1963 – distributed in a region in the Appalachian Mountains (eastern USA).

Siro sonoma Shear, 1980 – known from a locality in California. By a range of its unique characteristics, this species does not show any relationship to other sironids known to date and should be separated into a new genus related to Siro.

Siro platypedibus Dunlop & Giribet, 2003 – the only fossil Cyphophthalmi species known to date, described on the basis of a female found in the Bitterfeld amber in Germany, estimated to be between 20 to 40 million years old. This specimen has no one visible relevant detail that could establish its belonging to any genus. Although its belonging to the genus Siro may be logically assumed, its definite position in this genus is a mere speculation. The character of laterally flattened articles of some legs, emphasized by the authors as an apomorphic trait and an indication of a kind of speciation, is in my opinion wrongly interpreted. The flattened legs of this specimen are likely to be the consequence of the animal’s fall into the resin that conserved it. This happens frequently when the appendages are submerged in a concentrated viscose medium (Faure’s medium or Canada balsam) used in making slides – a difficulty I have encountered many times.

The monotypic genus Neosiro Newell, 1943 was synonymized with Siro by Shear (1980), in my opinion without strong evidence. Neosiro kamiakensis Newell, 1943 distributed in the north-west of the USA (Washington and Idaho) is therefore excluded from the genus Siro in the present paper.