Molecular support for morphology‐based family‐rank taxa: The contrasting cases of two families of Proseriata (Platyhelminthes)

Abstract

Representatives of the Meidiamidae and Otomesostomidae (Platyhelminthes:Proseriata) are seldom encountered, and the monophyly and phylogenetic relationships of these families have never been assessed on molecular basis. Here, we present the first exhaustive molecular study of Proseriata at the family level, including species belonging to the genera Meidiama and Yorknia (Meidiamidae), and Otomesostoma auditivum (Otomesostomidae), using 18S and 28S genes as markers. We performed phylogenetic analyses (Maximum Likelihood [ML] and Bayesian Inference [BI] methods) and species delimitation methods (Single/Multiple Threshold-Generalized Mixed Yule Coalescent [ST/MT-GMYC] and Poisson Tree Processes [PTP/bPTP]). The taxon Meidiamidae was not supported, since the type species (Meidiama lutheri) and Meidiama etrusca sp. n. are nested within the Archimonocelididae, formerly restricted to specialized cnidarian feeders. Species belonging to the genus Yorknia resulted genetically well separated from species of Meidiama and from the rest of Archimonocelididae. The new family-level taxon Yorkniidae fam. n. is thus here introduced, to include the type species of Yorknia (Yorknia aprostatica), and six new species, five of which are formally described here. Otomesostoma auditivum, representative of Otomesostomidae, the only exclusively freshwater taxon of the Proseriata, is the sister taxon of the predominantly marine Apingospermata. This result is not conflictual with the family level attributedto Otomesostomidae on morphological grounds, but it raises speculations on the marine versus freshwater origin of Apingospermata.

DNA barcoding of marine fishes from Saudi Arabian waters of the Gulf

“…The resulting map assesses whether data are reliable for phylogenetic and taxonomic inferences (Strimmer & von Haeseler, 1996). In this case, as well as for all cases in which dense sampling is not easy to obtain (Scarpa et al, 2017a), this condition may also reflect inadequate taxonomic coverage. Statistics and parameters such as base frequencies, GC content and conservative, variable and parsimony informative sites were estimated by means of R packages ape (Analysis of Phylogenetics and Evolution; Paradis et al, 2004) and spider (SPecies IDentity and Evolution in R; Brown et al, 2012) implemented in the R statistical environment (www.cran.rproject.org).…”

Polyclad phylogeny persists to be problematic

“…MAFFT Q-INS-i is by far the most computationally demanding alignment method, and was also employed quite extensively for resolving flatworm interrelationships on the level of orders based on partial 18S and 28S, e.g. macrostomorphs (Janssen et al 2015), rhabdocoels (van Steenkiste et al 2013Tessens et al 2014) and proseriates (Casu et al 2014;Scarpa et al 2015Scarpa et al , 2016Scarpa et al , 2017. The two best-scoring 18S28Slong trees are both based on a MAFFT Q-INS-i alignment ( Figs.…”

A complex species complex: The controversial role of ecology and biogeography in the evolutionary history of Syllis gracilis Grube, 1840 (Annelida, Syllidae)

“…DNA sequence data allowed to identify four divergent mitochondrial lineages within the Mediterranean S. gracilis . Invertebrates often show discrepancies among different methods of species delimitation (Fontaneto, Flot, & Tang, ; Mills et al, ; Scarpa, Cossu, Delogu, et al, ; Scarpa, Cossu, Sanna, et al, ; Tang et al, ), especially comparing methods based on different criteria (i.e., PSC‐based vs. genetic distance‐based methods) (Scarpa et al, ). In this case, only NDT identified four entities corresponding to the four lineages identified by both the Bayesian phylogenetic reconstruction and maximum parsimony haplotype network, whereas PTP/bPTP identified five entities, and ABGD six.…”

“…The NDT method works on sequences in order to ranks taxa into entities applying the fixed threshold of 2% given by Hebert et al () for DNA barcodes, using a pairwise Kimura () two‐parameter model (K2P) genetic distances matrix. Analysis was performed by means of a script (see Scarpa, Cossu, Delogu, et al, for details) written for the R statistical environment (available at https://cran.r-project.org/).…”

“…LG1 and LG2 (Fontaneto, Flot, & Tang, 2015;Mills et al, 2017;Scarpa, Cossu, Delogu, et al, 2017;Tang et al, 2012), especially comparing methods based on different criteria (i.e., PSC-based vs. genetic distancebased methods) (Scarpa et al, 2016). In this case, only NDT identified four entities corresponding to the four lineages identified by both F I G U R E 5 Bayesian phylogenetic tree, results of species delimitation methods and haplotype networks based on 16S sequences.…”