Henttonen, H. (2010). Systematic relationships of hymenolepidid cestodes of rodents and shrews inferred from sequences of 28S ribosomal RNA. -Zoologica Scripta, 39, 631-641. This study attempts to elucidate systematic relationships of hymenolepidid cestodes of rodents (18 species), shrews (13 species) and bats (one species) using sequences of partial 28S ribosomal RNA, with special reference to the genus Rodentolepis. The main finding is the presence of four multispecies clades of hymenolepidid cestodes showing pronounced morphological variation and frequent colonizations between unrelated hosts. Neither the hymenolepidid cestodes of shrews nor rodents were monophyletic. Also, the genus Rodentolepis sensu Vaucher in Czaplinski & Vaucher (1994, Keys to the Cestode Parasites of Vertebrates. Commonwealth Agricultural Bureaux International, Cambridge) is clearly nonmonophyletic. Although rostellar morphology is obviously a key feature on specific and generic levels, on higher systematic levels it seems to be a rather poor indicator of phylogenetic affinity in hymenolepidid cestodes. The presence of clades with more than one rostellar type (armed rostellum present, rudimentary unarmed rostellum present and rostellum absent) also conflicts with the proposed subfamilial and tribal classifications of hymenolepidid cestodes. The overall evidence suggests that the recent trend of splitting hymenolepidid cestodes into multiple genera will produce a more stable and practical classification than the earlier practice of favouring a few, morphologically variable genera. New classifications of hymenolepidid cestodes should, however, consider both morphological and molecular evidence.

We applied Bayesian phylogenetics, divergence time estimation, diversification pattern analysis, and parsimony-based methods of ancestral state reconstruction to a combination of nucleotide sequences, maximum body sizes, fossils, and paleoclimate data to explore the influence of an extrinsic (climate change) and an intrinsic (maximum body size) factor on diversification rates in a North American clade of catfishes (Ictaluridae). We found diversification rate to have been significantly variable over time, with significant (or nearly significant) rate increases in the early history of Noturus. Though the latter coincided closely with a period of dramatic climate change at the Eocene-Oligocene boundary, we did not detect evidence for a general association between climate change and diversification rate during the entire history of Ictaluridae. Within Ictaluridae, small body size was found to be a near significant predictor of species richness. Morphological stasis of several species appears to be a consequence of a homoplastic increase in body size. We estimated the maximum standard length of the ictalurid ancestor to be approximately 50 cm, comparable to Eocene ictalurids (Astephus) and similar to modern sizes of Ameiurus and their Asian sister-taxon Cranoglanis. During the late Paleocene and early Eocene, the ictalurid ancestor diversified into the lineages represented by the modern epigean genera. The majority of modern species originated in the Oligocene and Miocene, most likely according to a peripheral isolates model of speciation. We discuss the difficulties of detecting macroevolutionary patterns within a lineage history and encourage the scrutiny of the terminal Eocene climatic event as a direct promoter of diversification.

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.

This study reviews the taxonomy of cestodes of the genus Catenotaenia Janicki, 1904 (Cyclophyllidea: Catenotaeniidae) in Eurasia and presents the first molecular phylogenetic hypothesis of Catenotaenia, Skrjabinotaenia Ahumyan, 1946 and Meggittina Lynsdale, 1953, all parasites of rodents. The phylogenetic data are based on sequences of 28S ribosomal RNA. The analysis does not support the proposed subfamilial classification of the Catenotaeniidae into Catenotaeniinae Spasskii, 1949 and Skrjabinotaeniinae Genov & Tenora, 1979. Instead, the main division appears to be between Eurasian species and a basal Nearctic species. The results support the monophyly of the Skrjabinotaeniinae but not that of the Catenotaeniinae or Catenotaenia as traditionally understood. It is suggested that the Old World catenotaeniid cestodes appeared in murid rodents and diverged subsequently as Skrjabinotaenia and Meggittina (Skrjabinotaeniinae) in Africa. According to the molecular phylogeny, Eurasian Catenotaenia codiverged with their hosts, with the exception of Catenotaenia dendritica that originated via a host shift from murid rodents to squirrels. The crown clade of Eurasian Catenotaenia consists only of species found in cricetid rodents and the three terminal species only in the Arvicolinae (voles). Phylogenetic structure within the Eurasian Catenotaenia clade suggests seven distinct lineages, three of which are described as new: C. apodemi n. sp. from Apodemus peninsulae (type host) from the Republic of Buryatia and from Apodemus uralensis from the Lower Tunguska River, North-Central Siberia (Russian Federation); C. cricetuli n. sp. from Cricetulus barabensis from the Republic of Buryatia and C. microti n. sp. from Microtus socialis from Kazakhstan. A new genus (Catenotaenioides n. g.) is proposed for C. kirgizica Tokobaev, 1959, a basal species within the Old World clade. Of the various morphological features, proglottid form (short acraspedote proglottids widest at middle vs. elongated craspedote proglottids widest posteriorly) is consistent with the phylogenetic pattern exhibited by catenotaeniid cestodes.

2008). Molecular systematics and morphometrics of Anoplocephaloides dentata (Cestoda, Anoplocephalidae) and related species in 38 , This study presents extensive molecular phylogenetic and morphometric data for Anoplocephaloides dentata (Galli-Valerio, 1905)-like cestodes (Anoplocephalidae) and related species parasitizing arvicoline rodents (voles and lemmings) in the Holarctic region. The molecular phylogeny is based on nucleotide sequences of cytochrome oxidase I (mtDNA) and 28S ribosomal RNA. Anoplocephaloides dentata -like cestodes included three main clades, two in western Eurasia and one in the Holarctic region (excluding western Eurasia). Three well-supported sublineages were included in the southern European clade, one of which represents the true A. dentata from Chionomys nivalis and sympatric Microtus arvalis and Dinaromys bogdanovi . These clades generally had non-overlapping distributions and showed a preference for certain host species. Multivariate analysis of morphometric data failed to discriminate unambiguously the various A. dentata -like lineages recovered in the molecular phylogeny, although two to three of the (sub)lineages were morphologically divergent. The overall evidence suggests, however, that instead of a single host-generalist species there are at least five more or less host-specific species of A. dentata -like cestodes. Colonization of new host lineages seems to have been the predominant mode of diversification, suggested by the considerable incongruence between host and parasite phylogenies at multiple taxonomic levels. Based on the results of the molecular survey, a redescription and neotype designation are provided for A. dentata .