Abstract
In 2005 a new, non-indigenous crayfish species was discovered in the Dessoubre River (eastern France). The species was initially considered as Orconectes rusticus (Girard, 1852). However, an examination of form I males caught in 2007 revealed that the species is in fact Orconectes juvenilis (Hagen, 1870), a closely related congener of O. rusticus. According to our knowledge, this is the first record of O. juvenilis outside the North American continent. The ecological implications as well as the possible impact on the native European crayfish are discussed briefly.
Highlights
In November 2005 a previously unknown Orconectes species was discovered in the Dessoubre River, a tributary of the Doubs
The form I males were subsequently compared to preserved O. rusticus specimens and identified as Orconectes (Procericambarus) juvenilis (Hagen, 1870; Figure 1), a species closely related to O. rusticus (Taylor 2000)
Orconectes juvenilis resembles the habitus of O. rusticus and only differs from rusty crayfish in form I gonopod characteristics: In O. juvenilis the terminal elements of form I gonopods are more elongated and the ratio of central projection length to total gonopod length is greater (Taylor 2000, see Taylor and Schuster 2004 for gonopod terminology)
Summary
In November 2005 a previously unknown Orconectes species was discovered in the Dessoubre River, a tributary of the Doubs The introduced species was identified erroneously as rusty crayfish [Orconectes (Procericambarus) rusticus (Girard, 1852)], a common and largely translocated species in North America (cf Souty-Grosset et al 2006). In August 2007 we collected several specimens from the restaurant ponds, including seven form I males.
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