Systematics and phylogeny of Potamotrygonocestus (Platyhelminthes, Tetraphyllidea, Onchobothriidae) with descriptions of three new species from freshwater potamotrygonids (Myliobatoidei, Potamotrygonidae)

Abstract

Specimens of Potamotrygonocestus used in the present taxonomic and phylogenetic study were collected in freshwater potamotrygonids from the Rio Paraná (Puerto Reconquista, Santa Fé, Argentina; 59°42′W, 29°29′S) during February 1995, and from the Amazon region of Brazil during September to December 1996, supplemented by specimens previously deposited in museum collections. Six species of Potamotrygonocestus were recognized (P. amazonensis, P. chaoi sp. n., P. fitzgeraldae sp. n., P. magdalenensis, P. maurae sp. n., P. travassosi), for which an identification key is provided. Potamotrygonocestus orinocoensis is considered a junior synonym of P. travassosi. Additional specimens of Potamotrygonocestus may represent two undescribed species. A phylogenetic analysis of six morphological characters for the six named species of Potamotrygonocestus generated a single tree eight steps long, with a consistency index of 0.87, a retention index of 0.90, and a rescaled consistency index of 0.79 with the following topology: (P. maurae sp. n. ((P. amazonensis + P. magdalenensis) (P. chaoi sp. n. (P. fitzgeraldae sp. n. + P. travassosi)))).

Molecular phylogeny of Potamotrygonocotyle (Monogenea, Monocotylidae) challenges the validity of some of its species

“…The host specificity level and the geographic distribution of its constituent species vary considerably, ranging from strict specificity and endemism to widespread occurrence in several host species and sub‐basins (Domingues & Marques 2007, 2011; Domingues et al. 2007), a pattern similar to those already reported for some of the cestodes inhabiting potamotrygonids (Marques & Brooks 2003; Marques et al. 2003).…”

“…Investigations into the parasite fauna of potamotrygonids, which is predominantly represented by platyhelminths, have mainly focused on cestodes (Marques & Brooks 2003; Marques et al. 2003; Luchetti et al.…”

New Species of Gieysztoria (Platyhelminthes, Rhabdocoela) from Peruvian Amazon Floodplain with Description of their Stylet Ultrastructure

“…Most of the well-known Platyhelminthes from the Amazon basin belong to the parasitic classes (Neodermata): Cestoda, Trematoda and Monogenea ( e.g. Thatcher, 1993;Carvalho et al, 2001;Marques et al, 2003;Belmont-Jegu et al ;2004;Rego, 2004) whereas the free-living Platyhelminthes are almost unknown. Presently only four species have been mentioned from the Amazon river (floodplain and tributaries): Xenostenostomum microstomoides Reisinger, 1976, Dugesia fissipara (Kennel, 1888 Ball, 1974 (Marcus, 1948) captured near the Amazon estuary, and more recently, Sergia sp.…”

Diversidade filogenética de Potamotrygonocestus Brooks & Thorson, 1976 (Eucestoda: Onchoproteocephalidea)

“…Recentemente, Machado (2012) propôs uma hipótese filogenética para as linhagens de água doce de Acanthobothrium e testou a monofilia das espécies propostas por Cardoso (2010) utilizando dados moleculares. Para Potamotrygonocestus Brooks & Thornson, 1976, são reconhecidas onze linhagens com base em dados fenotípicos (Brooks & Thorson, 1976;Brooks et al, 1981;Marques et al, 2003;Luchetti et al, 2008), sendo que quatro delas ainda aguardam descrição formal (Luchetti, 2011). As relações filogenéticas das espécies deste gênero foram esboçadas em dois estudos utilizando dados morfológicos (Brooks, 1992;Marques et al, 2003), mas nenhuma destas hipóteses contempla a diversidade atualmente reconhecida para o gênero.…”

“…Para Potamotrygonocestus Brooks & Thornson, 1976, são reconhecidas onze linhagens com base em dados fenotípicos (Brooks & Thorson, 1976;Brooks et al, 1981;Marques et al, 2003;Luchetti et al, 2008), sendo que quatro delas ainda aguardam descrição formal (Luchetti, 2011). As relações filogenéticas das espécies deste gênero foram esboçadas em dois estudos utilizando dados morfológicos (Brooks, 1992;Marques et al, 2003), mas nenhuma destas hipóteses contempla a diversidade atualmente reconhecida para o gênero. Conclui-se que, apesar dos esforços destes autores em compreender a diversidade da fauna parasitária de potamotrigonídeos, diversas lacunas permanecem em nosso conhecimento impedindo a elucidação dos processos de diversificação desse sistema.…”