Integrative taxonomy reveals hidden cestode diversity in Pimelodus catfishes in the Neotropics

Abstract

Proteocephalid tapeworms are the dominant group of endoparasites in siluriform catfishes in South America, but their interrelationships and actual diversity remain poorly understood. Molecular prospecting of proteocephalids found in pimelodid and other catfishes, especially in Pimelodus spp., along with thorough morphological evaluation, revealed high species diversity of these parasites. Using newly obtained sequences of the partial large subunit nuclear ribosomal RNA (lsrDNA) and complete mitochondrial cytochrome c oxidase subunit I (COI), phylogenetic relationships of the cestodes of Pimelodus catfishes were assessed and a new genus, Pseudoendorchis gen. n., proposed to accommodate P. auchenipteri comb. n. (type species; formerly Endorchis auchenipteri), P. cristata sp. n. from Pimelodella cristata (Heptapteridae), P. felipei sp. n. from Pimelodus fur, P. souzalimae sp. n. from Pimelodus maculatus and another three putative new species. Members of the new genus can be readily distinguished from all known Neotropical proteocephalids by having a large Mehlis’ gland, representing at least 18% of proglottid width, and the vagina always anterior to the cirrus‐sac. Moreover, all phylogenetic, species discovery and validation analyses support validity of Pseudoendorchis. Combining the lsrDNA + COI sequence data appeared to provide the best resolution in phylogenetic analyses, which may be useful to reduce the uncertainty of the interrelationships among Neotropical proteocephalids.

The multilevel organismal diversity approach deciphers difficult to distinguish nudibranch species complex

“…nov., despite the presence of robust external, internal, and molecular differences (Figs. 1,2,3,4,8,9). Thus, the periodic-like mapping of the polychromatic variants in combination with statistical analysis of the diagnostic characters is an important tool in addition to the molecular phylogenetic analysis.…”

“…nov. (Figs. 1,3,5,9). For each of these species we provided diagnostic characters that are based not just on traditional taxonomic "listing" of some features, but on statistically supported analysis of key external features.…”

“…When application of molecular data became a routine, any potentially hidden lineages were labelled as "cryptic species" 8 . Recently several studies independently showed that this counterproductively disrupts organismal diversity into "cryptic" and "non-cryptic" species [9][10][11][12] .…”

Hidden diversity of the most basal tapeworms (Cestoda, Gyrocotylidea), the enigmatic parasites of holocephalans (Chimaeriformes)

“…(Rhinebothriidea) and the yellownose skate Dipturus chilensis (Guichenot); and Pseudoendorchis spp. (Onchoproteocephalidea) and the catfish Pimelodus maculatus Lacepède [34][35][36] .…”

Description of the first species of Pseudoendorchis (Cestoda: Proteocephalidae) with uniloculate suckers from the pimelodid catfish Megalonema platycephalum, with comments on the taxonomic importance of the terminal vagina

“…The application of molecular tools combined with classical morphological analysis has significantly improved our understanding of the diversity, phylogenetic relationships, host-associations, and distribution of cestode parasites in vertebrates around the globe (Caira & Jensen, 2017). Using this integrative approach, Alves et al (2021a) erected the genus Pseudoendorchis Alves, de Chambrier, Luque & Scholz, 2021 (Cestoda: Onchoproteocephalidea) to accommodate four species, namely P. auchenipteri (de Chambrier & Vaucher, 1999) (type species) from Auchenipterus osteomystax (Miranda-Ribeiro) (Auchenipteridae, type host) in Paraguay and Pimelodus maculatus Lacepe `de (Pimelodidae) in Brazil, both from the Parana ´River basin (PRB); P. cristata Alves, de Chambrier, Luque & Scholz, 2021 from Pimelodella cristata (Mu ¨ller & Troschel) (Heptapteridae) in the Amazon River basin (ARB) in Brazil; P. felipei Alves, de Chambrier, Luque & Scholz, 2021 from Pimelodus fur (Lu ¨tken) (Pimelodidae) in Brazil (Miranda River, PRB); and P. souzalimae Alves, de Chambrier, Luque & Scholz, 2021 from Pimelodus maculatus in Brazil (Parana ´and Miranda Rivers, both PRB). In addition, three putative new species were recognised based on molecular data (lsrDNA and COI sequences), but they were not formally described due to either poor quality or incompleteness of the material available (Alves et al, 2021a).…”