Chromosomes of the caryophyllidean tapeworm Glaridacris laruei

New cytogenetic data on Caryophyllaeus laticeps and Paracaryophyllaeus gotoi, parasites of evolutionary interest

Caryophyllideans are intestinal parasites of freshwater fishes, occupying a basal position among the ‘true’ tapeworms. We performed detailed cytogenetic analyses of the well-known caryophyllidean species Caryophyllaeus laticeps. For comparison, we also examined for the first time the chromosomes of Paracaryophyllaeus gotoi, a specific parasite of loaches in China. Both species showed a diploid chromosome number of 2n = 20, n = 10m. Chromomycin A3 (CMA3)/diamidino-2-phenylindole (DAPI) staining performed for the first time in the class Cestoda revealed CMA3+/DAPI− bands in the pericentromeric regions of the short arms of chromosome pair no. 7 in the karyotype of C. laticeps. Fluorescence in situ hybridization with the 18S rDNA probe confirmed the presence of a single cluster of major rDNA near the centromere on a pair of small chromosomes in both species. These findings support the hypothesis that the ancestral state in the family Caryophyllaeidae is a single interstitial cluster of major rDNA genes and thus one nucleolar organizer region per haploid genome. Our results, which we presented together with literature data plotted on a phylogenetic tree, show stability of caryophyllidean karyotypes at the genus level, but showed differences between genera without a clear phylogenetic signal. The data allowed us to at least formulate a hypothesis about the ancestral haploid chromosome number of n = 10 for the family Caryophyllaeidae and possibly for the sister family Capingentidae. In addition, we compared two populations of C. laticeps from water bodies with different levels of polychlorinated biphenyl contamination, showing a slightly increased incidence of chromosomal abnormalities at the contaminated site.

A New Classification of Glaridacris Cooper, 1920 (Cestoda: Caryophyllidea), Parasites of Suckers (Catostomidae) in North America, Including Erection of Pseudoglaridacris N. Gen

A taxonomic study of monozoic cestodes of the genus Glaridacris Cooper, 1920 (Cestoda: Caryophyllidea), parasites of catostomid fishes in North America, confirmed artificial character of the genus which is split to 2 different, morphologically distinct, and not closely related genera. Glaridacris is newly circumscribed to include only 3 species, Glaridacris catostomi Cooper, 1920 (type species), Glaridacris terebrans ( Linton, 1893 ), and Glaridacris vogei Mackiewicz, 1976 , which are characterized by an elongate body, a cuneiloculate or wedge-shaped scolex with 6 shallow loculi, male and female gonopores at a distance from each other, follicular ovary, and circum-medullary vitelline follicles (lateral and median). A new genus, Pseudoglaridacris n. gen., is proposed to accommodate 3 species characterized by a shorter body, a bothrioloculodiscate scolex with a pair of deeper median bothria and 2 shallower loculi, male and female gonopores close together, non-follicular ovary, and with only lateral vitelline follicles. The species are: Pseudoglaridacris laruei ( Lamont, 1921 ) n. comb. (type species), Pseudoglaridacris confusa (Hunter, 1929) n. comb., and Pseudoglaridacris oligorchis ( Haderlie, 1953 ) n. comb. An annotated list of all species of both genera, with data on their hosts and distribution and keys to their identification, is provided.

Cytogenetics and chromosomes of tapeworms (Platyhelminthes, Cestoda)

Tapeworms (Cestoda, Platyhelminthes) are a highly diversified group of parasites that can have significant veterinary importance as well as medical impact as disease agents of human alveococcosis, hydatidosis, taeniosis/cysticercosis/neurocysticercosis, hymenolepidosis or diphyllobothriasis. Because of their great diversity, there has been keen interest in their phylogenetic relationships to other obligate parasitic platyhelminthes, as well as within the group itself. Recent phylogenetic analyses of cestodes, however, have focused on morphological, molecular, life cycle, embryology and host-specificity features and conspicuously omitted inclusion of karyological data. Here we review the literature from 1907 to 2010 and the current status of knowledge of the chromosomes and cytogenetics within all of the cestode orders and place it within an evolutionary perspective. Karyological data are discussed and tabulated for 115 species from nine eucestode orders with ideograms of 46 species, and a comparison of cytogenetic patterns between acetabulate and bothriate cestode lineages is made. Attention is drawn to gaps in our knowledge for seven remaining orders and cestodarian groups Gyrocotylidea and Amphilinidea. Among the cytogenetic aspects covered are: chromosome number, triploidy, classical karyotype cytogenetics (banding patterns, karyotype asymmetry, secondary constrictions), as well as advanced karyotype techniques allowing location of genes on chromosomes by fluorescence in situ hybridization. We demonstrate that further progress in cestode karyosystematics rests with new molecular approaches and the application of advanced cytogenetic markers facilitating intimate karyotype analysis.

Diversity of Dilepididae (Cestoda: Cyclophyllidea) revealed by cytogenetic analysis

Karyotypes of three dilepidid species:Molluscotaenia crassiscolex,Anomotaenia bacilligeraandDilepis undula,which have not been recorded previously, were studied using conventional Giemsa staining and comparative karyometric analysis. Twelve small biarmed chromosomes were observed in mitotic cells ofM. crassiscolex, 16 biarmed chromosomes of gradually decreasing size were found in cells ofA. bacilligera, while 18 elements were characteristic forD. undula. These data, together with information available in literature, prove the heterogeneity and possible polyphyletic nature of the family Dilepididae.

A chromosome study in the progenetic cestode Cyathocephalus truncatus (Cestoda:Spathebothriidea)

The chromosomes of somatic cells of progenetic Cyathocephalus truncatus, parasite of amphipod crustaceans, Gammarus lacustris, from North-West Chukotka were investigated using standard Giemsa staining. The karyotype, not described previously, consists of 9 pairs of chromosomes (2n = 18), the most widespread number among cestodes. A considerable number of polypoid cells (34.7%) was noted in preparations. The chromosomes are comparatively large, up to 12.26 microns. According to centromeric index values, chromosomes 1 and 4 subtelocentric; 2, acrocentric to subtelocentric; 3 and 5, acrocentric; 6 and 9, metacentric; 7 submeta-subtelocentric; and 8, submetacentric. These characteristics are discussed with reference to the karyotypes previously described within other closely related groups caryophyllideans and pseudophyllideans.