Phylogenetics of Echinodorus (Alismataceae) based on morphological data

Abstract

Echinodorus (Alismataceae) is a genus of aquatic and semi-aquatic herbs naturally distributed from Argentina to the USA but commonly used as ornamentals in aquaria worldwide. The phylogeny of the genus was studied on the basis of 96 morphological characters. The analysis resulted in a single most-parsimonious tree supporting a polyphyletic origin of the genus. However, subgenus Echinodorus together with Echinodorus nymphaeifolius formed a clade. Two large clades can be recognized in Echinodorus s.s. , but previous subdivisions of the genus are not supported and some earlier proposed subspecific combinations were shown to be non-monophyletic. Addition of continuous characters coded as value ranges enhanced both the resolution and the support values of the tree. Hence, inclusion of continuous overlapping data is encouraged in phylogenetic studies.

On the origin of Echinodorus grandiflorus (Alismataceae) in Florida (“E. floridanus”), and its estimated potential as an invasive species

“…Recent advances in Echinodorus systematics (Lehtonen, 2006;Lehtonen & Myllys, 2008) revealed several unnatural species and subspecies level rankings in previous classifications, which resulted in a partial revision of the genus (Lehtonen, 2008). The close affinity of Echinodorus floridanus with a South American species E. grandiflorus was already suspected by Haynes & Burkhalter (1998), and the conspecific status of the two was confirmed by morphological (Lehtonen, 2006) and molecular evidence (Lehtonen & Myllys, 2008). This ledto the formal synonymization of the name E. floridanus under E. grandiflorus (Cham.…”

An integrative approach to species delimitation in Echinodorus (Alismataceae) and the description of two new species

“…The species delimitation proposed here is based on studies of c. 3000 herbarium specimens deposited in AAU, AMAZ, BA, BM, BR, C, CAR, CTES, FCQ, H, K, LPB, M, MEXU, MVFA, MVFQ, MVJB, MVM, MY, MYF, PR, PY, Q, QCA, QCNE, QPA, S, SI, TUR, U, UC, UNA, VEN, and W, (herbarium codes according to Holmgren & Holmgren 1998) studies on digital images of selected herbarium sheets deposited in B, BH, F, G, G-DC, GOET, MOR, NY, P, PH, RB, SP, UB, and US, intensive field studies in different parts of the range of the genus (113 populations studied), and on phylogenetic studies of both morphological characters and matK, ITS1;2, LEAFY, and 5S-NTS sequences (Lehtonen 2006;Lehtonen & Myllys 2008). Morphological, plastid DNA, and nuclear DNA data sets were interpreted to be congruent on the basis of tree-similarity measurements, which were obtained by calculating the minimum number of SPR moves required to transform a tree obtained from one data set into the tree obtained from another data set (Goloboff et al 2003;Lehtonen & Myllys 2008).…”

“…Afterwards considered Helanthium as a subgenus of Echinodorus and later workers have followed this classification. In recent phylogenetic analyses (Lehtonen 2006;Lehtonen & Myllys 2008) Echinodorus sensu lato was found to be polyphyletic, and in order to obtain a monophyletic circumscription of the genus the classification proposed by Pichon was followed by transferring E. nymphaeifolius into Albidella, and E. bolivianus, E. tenellus and E. zombiensis into Helanthium (Lehtonen & Myllys 2008).…”

“…Recent advances in Echinodorus phylogenetics have revealed several unnatural species and subspecies level rankings thus resulting in the need for a partial revision of the genus (Lehtonen 2006;Lehtonen & Myllys 2008). In the present study, I examine further the results of the combined analysis of molecular and morphological data by Lehtonen & Myllys (2008) in order to achieve a more reliable, phylogeny-based species delimitation in Echinodorus.…”

Taxonomic, nomenclatural and chorological notes on several taxa of the genus Echinodorus (Alismataceae)

“…coming from the natural site in the vicinity of the city Santa Fé in Argentina [the name E. aschersonianus is a synonym of the earlier name E. uruguayensis Arechav. (Lehtonen, 2006)]. From the achenes, plants of different phenotypes were grown (possibly different species?…”