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Research Papers
Introduction
The family Hymenolepididae is the richest in number of recorded species of all families within Eucestoda, with about 850 species: 230 in mammals, the rest in birds (Czaplinski & Vaucher, 1994). Czaplinski & Vaucher (1994) listed 34 valid genera of mammalian hymenolepidids, with eight of them primarily or exclusively from rodents. Of these, Hymenolepis (sensu stricto) and Rodentolepis Spasskii, 1954 are the most species-rich genera found in rodents.
There has been much controversy and confusion with regard to Rodentolepis straminea since it was first (inadequately) described by Goeze in 1782 and named as Taenia straminea (summarized by Baer & Tenora, 1970). Currently there is still some disagreement over whether this species should be assigned to Hymenolepis or Rodentolepis. It was originally assigned to the genus Rodentolepis Spasskii, 1954, which was erected for hymenolepidids with numerous hooks from mammals, and R. straminea was designated a type species of the group (Czaplinski & Vaucher, 1994). However, Cunningham & Olson (2010) argued that the more common usage of Hymenolepis should be adopted, but stated that more defined molecular analyses would be required to fully interpret the systematics. Subsequently, a study by Haukisalmi et al. (2010) on the systematic relationships of hymenolepidid cestodes of rodents and shrews, using partial sequences of 28S ribosomal RNA, placed R. straminea in the 'Rodentolepis' clade. Recent papers refer to R. straminea, and in the Fauna Europaea (www.faunaeur.org) this is listed as the accepted name (updated in 2013). The genus Rodentolepis includes armed cestodes with a single row of numerous hooks and testes in a row or elongated triangle, separated into two groups by the female gonads; whereas the genus Hymenolepis includes only species with a rudimentary rostellar apparatus and no rostellar hooks, such as Hymenolepis diminuta. Therefore, in this paper R. straminea will be used.
Rodentolepis straminea was also originally thought to be synonymous with Rodentolepis microstoma; however, morphological examination and protein electrophoresis have now shown these to be separate species (Casanova et al., 2001). Morphologically, R. straminea and R. microstoma are very similar and difficult to differentiate. The main method of distinguishing between the two species is based on identification of...