A large 28S rDNA-based phylogeny confirms the limitations of established morphological characters for classification of proteocephalidean tapeworms (Platyhelminthes, Cestoda)

Abstract

Proteocephalidean tapeworms form a diverse group of parasites currently known from 315 valid species. Most of the diversity of adult proteocephalideans can be found in freshwater fishes (predominantly catfishes), a large proportion infects reptiles, but only a few infect amphibians, and a single species has been found to parasitize possums. Although they have a cosmopolitan distribution, a large proportion of taxa are exclusively found in South America. We analyzed the largest proteocephalidean cestode molecular dataset to date comprising more than 100 species (30 new), including representatives from 54 genera (80%) and all subfamilies, thus significantly improving upon previous works to develop a molecular phylogeny for the group. The Old World origin of proteocephalideans is confirmed, with their more recent expansion in South America. The earliest diverging lineages are composed of Acanthotaeniinae and Gangesiinae but most of the presently recognized subfamilies (and genera) appear not to be monophyletic; a deep systematic reorganization of the order is thus needed and the present subfamilial system should be abandoned. The main characters on which the classical systematics of the group has been built, such as scolex morphology or relative position of genital organs in relation to the longitudinal musculature, are of limited value, as demonstrated by the very weak support for morphologically-defined subfamilies. However, new characters, such as the pattern of uterus development, relative ovary size, and egg structure have been identified, which may be useful in defining phylogenetically well-supported subgroups. A strongly supported lineage infecting various snakes from a wide geographical distribution was found. Although several improvements over previous works regarding phylogenetic resolution and taxon coverage were achieved in this study, the major polytomy in our tree, composed largely of siluriform parasites from the Neotropics, remained unresolved and possibly reflects a rapid radiation. The genus Spasskyellina Freze, 1965 is resurrected for three species of Monticellia bearing spinitriches on the margins of their suckers.

Diversity of ectoparasites and endoparasites infecting Brachyplatystoma vaillantii (Siluriformes: Pimelodidae), a large migratory catfish from the Amazon

“…Hence, Cestoda is the endohelminth taxon most known for infecting B. vaillantii (Rego 1984;Alves et al 2017a,b). The prevalence of H. piramutab in B. vaillantii was lower than that reported by Chambrier et al (2015) for this same host from the Peruvian ACTA AMAZONICA Amazon, and the species also occurred in low mean abundance and intensity in our sample. Our study expands the occurrence of H. piramutab to the eastern Amazon.…”

“…In the Peruvian Amazon, B. vaillantii was found to be infected with the cestodes Chambriella sp. and H. piramutab, and monogeneans of the genus Demidospermus (Mendoza-Palmero et al 2015;Chambrier et al 2015). In Venezuela, the infection of B. vaillantii by G. siluri and Harriscolex kaparari (Woodland, 1935) Rego, 1987(Alves et al 2017a was reported.…”

‘What’s on your mind?’ The only necessary question in spiritual care

“…Being understood is not as important as being truly heard on this view. Understanding may not necessarily be possible, nor in everyone's gift (Häfner 2015). Hearing the story is though.…”

Ultrastructure and histochemistry of the scolex of two Neotropical proteocephalidean species (Cestoda: Onchoproteocephalidea)

“…The proteocephalideans are a monophyletic group inside of the order Onchoproteocephalidea (de Chambrier et al, 2004, 2015, 2017). In their adult stage, they parasitize a wide range of hosts including bony fishes, amphibians, reptiles, and mammals (de Chambrier et al, 2017).…”