Molecular systematics of the Holarctic Anoplocephaloides variabilis (Douthitt, 1915) complex, with the proposal of Microcephaloides n. g. (Cestoda: Anoplocephalidae)

Abstract

Phylograms based on mitochondrial cytochrome oxidase I gene sequences show that the Anoplocephaloides variabilis (Douthitt, 1915)-like cestodes (Cestoda: Anoplocephalidae) from voles (Microtus spp.) and Paranoplocephala krebsi Haukisalmi, Wickström, Hantula & Henttonen, 2001 from collared lemmings (Dicrostonyx spp.) comprise a monophyletic group within the anoplocephaline cestodes. The patterns of phylogenetic, biological and/or biogeographical distinction suggest six or seven species of A. variabilis-like cestodes, including P. krebsi. However, at this time we decline to describe them as a series of new species as no straightforward morphological differences were found between the A. variabilis-like cestodes. A new genus, Microcephaloides n. g., is proposed for the cestodes earlier assigned to A. variabilis, A. cf. variabilis, A. tenoramuraiae Genov & Georgiev, 1988 and P. krebsi. A redescription is provided for the type-species, M. variabilis n. comb., from pocket gophers (Geomys spp. and Thomomys spp.). In addition to Anoplocephaloides Baer, 1927 (sensu stricto) and Microcephaloides, Paranoplocephaloides Gulyaev, 1996, Flabelloskrjabinia Spasskii, 1951 and Leporidotaenia Genov, Murai, Georgiev & Harris, 1990 are considered valid genera among cestodes previously assigned to Anoplocephaloides (sensu Rausch, 1976). The host spectrum and present phylogenetic data suggest that Microcephaloides has been primarily associated with voles (Microtus spp.) and its basal lineage now occurs in M. guentheri (Danford & Alston) in Turkey. Although the distribution and current host of the basal lineage suggest a western Palaearctic origin, subsequent diversification has probably occurred in eastern Beringia, because most of the more derived lineages occur partly or exclusively in Alaska.

Review of tapeworms of rodents in the Republic of Buryatia, with emphasis on anoplocephalid cestodes

“…(earlier known as Anoplocephaloides variabilis-like cestodes), appears to be absent in Buryatia, although it occurs widely in Europe and North America, and sporadically in North-East Siberia (Haukisalmi et al 2008). Th e high species diversity and endemism in Europe is partly due to the high taxonomic diversity of voles in that region; of the 14 vole and lemming species considered in the present comparison, seven occur exclusively in Europe or western Eurasia.…”

“…Th e present and earlier studies (Haukisalmi et al 2008, Haukisalmi et al 2004, Hu et al 2005 show that molecular markers, such COI sequences, are necessary tools in the taxonomy of anoplocephalid cestodes, which lack a rostellum and hooks and which can be devoid of reliable distinguishing features. It can be estimated that 50-60% of species diversity of anoplocephalid cestodes of voles and lemmings in the Holarctic region would have remained undetected if the taxonomy had been based on morphological features only (Table 2 and unpublished records of the BCP and present authors).…”

“…However, high European species diversity has also been indicated for anoplocephalid cestodes of lagomorphs (Spasskii 1951), suggesting that this phenomenon may have a more general biogeographical and/or historical explanation. Th e existing phylogenetic data indicate a possible European origin for Microcephaloides Haukisalmi, Hardman, Hardman, Rausch & Henttonen, 2008(see Haukisalmi et al 2008 and Paranoplocephala s. str. (see Haukisalmi et al 2004), suggesting that Europe may have acted as a centre of origin for several independent anoplocephalid lineages.…”

Review of Anoplocephaloides species from African rodents, with the proposal of Afrobaeria n. g. (Cestoda: Anoplocephalidae)

“…into several categories, such as those with a short and wide ("wedge-shaped") strobila, long and slender strobila and strobila of intermediate form (Rausch, 1976;Genov & Georgiev, 1988). The recent molecular phylogenetic analyses of anoplocephaline cestodes Haukisalmi et al, 2008) show that at least two of these categories represent monophyletic groups, i.e. the wedge-shaped Anoplocephaloides sensu stricto and Microcephaloides, the latter with a strobila of intermediate form.…”

“…Later, Gulyaev (1996) erected Paranoplocephaloides Gulyaev, 1996 for two species from arvicoline rodents. Recently, Anoplocephaloides variabilis (Douthitt, 1915) and related forms from arvicoline rodents were assigned to a new genus, Microcephaloides Haukisalmi, Hardman, Hardman, Rausch & Henttonen, 2008, based on morphological and molecular evidence (Haukisalmi et al, 2008). The Anoplocephaloides-like species from tapirs have also been assigned to a separate genus (i.e.…”