Molecular phylogenetic data and seed coat anatomy resolve the generic position of some critical Chenopodioideae (Chenopodiaceae – Amaranthaceae) with reduced perianth segments

Abstract

The former Chenopodiumsubgen.Blitum and the genus Monolepis (Chenopodioideae) are characterised in part by a reduced (0–4) number of perianth segments. According to recent molecular phylogenetic studies, these groups belong to the reinstated genera Blitum incl. Monolepis (tribe Anserineae) and Oxybasis (tribe Chenopodieae). However, key taxa such as C.antarcticum, C.exsuccum, C.litwinowii, C.foliosumsubsp.montanum and Monolepisspathulata were not included and so their phylogenetic position within the Chenopodioideae remained equivocal. These species and additional samples of Blitumasiaticum and B.nuttallianum were incorporated into an expanded phylogenetic study based on nrDNA (ITS region) and cpDNA (trnL-trnF and atpB-rbcL intergenic spacers and rbcL gene). Our analyses confirm the placement of C.exsuccum, C.litwinowii and C.foliosumsubsp.montanum within Blitum (currently recognised as Blitumpetiolare, B.litwinowii and B.virgatumsubsp.montanum, respectively); additionally, C.antarcticum, currently known as Oxybasisantarctica, is also placed within Blitum (reinstated here as B.antarcticum). Congruent with previous studies, two of the three accepted species of Monolepis – the type species M.trifida (= M.nuttalliana) as well as M.asiatica – are included in Blitum. The monotypic genus Carocarpidium described recently with the type C.californicum is not accepted as it is placed within Blitum (reinstated here as B.californicum). To date, few reliable morphological characters have been proposed that consistently distinguish Blitum (incl. two Monolepis species) from morphologically similar Oxybasis; however, two key differences are evident: (1) the presence of long-petiolate rosulate leaves in Blitum vs. their absence in Oxybasis and (2) a seed coat structure with the outer wall of the testa cells lacking stalactites (‘non-stalactite seed coat’) but with an obvious protoplast in Blitum vs. seed coat with the outer walls of the testa cells having stalactites (‘stalactite seed coat’) and a reduced protoplast in Oxybasis. Surprisingly, the newly sequenced North American Monolepisspathulata nested within the tribe Dysphanieae (based on ITS and trnL-trnF + rbcL + atpB-rbcL analyses).The phylogenetic results, as well as presence of the stalactites in the outer cell walls of the testa and lack of the rosulate leaves, confirm the distinctive nature of Monolepisspathulata from all Blitum and, therefore, the recent combination Blitumspathulatum cannot be accepted. Indeed, the morphological and molecular distinctive nature of this species from all Dysphanieae supports its recognition as a new monotypic genus, named herein as Neomonolepis (type species: N.spathulata). The basionym name Monolepisspathulata is also lectotypified on a specimen currently lodged at GH. Finally, while Micromonolepispusilla is confirmed as belonging to the tribe Chenopodieae, its position is not fully resolved. As this monotypic genus is morphologically divergent from Chenopodium, it is retained as distinct but it is acknowledged that further work is requ...

Seed Morphology in Silene Based on Geometric Models

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“…For this reason, we suggest geometric indexes applied to seed morphology as a tool. Combined with molecular phylogenetic data, geometric indexes could be used for phylogenetic classification, as it has been proposed in other plant species of difficult classification [ 48 ].…”

Taxonomic revision of Chenopodiaceae in Himalaya and Tibet

“…During the last fifteen years, the generic composition of many groups in the family has undergone extensive changes following molecular phylogenetic revisions, with the splitting or merging of many genera. Chenopodium was found to be polyphyletic and its members occupy different phylogenetic positions within Chenopodioideae (Fuentes et al 2012; Sukhorukov et al 2018). In the previous broader sense, Salsola appeared to be strongly polyphyletic (Akhani et al 2007), but in contrast, the formerly accepted genus Kochia is now merged with Bassia (Kadereit & Freitag, 2011).…”

Evaluation of seed morphology characteristics of Alnus taxa in Iran

“…Kaya et al (2011) believed that seed morphology characters are an important trait in taxonomical treatment of various families. These characteristics are mostly used to resolve taxonomical problems concerning closely related species, taxa delimitation and establish their evolutionary relationships (Sukhorukov et al, 2018).…”

“…There are several taxonomical treatments of the genus in Iran. For example, Shayanmehr et al (2014) evaluated morphological characteristics of different Alnus taxa in Iran. The molecular phylogeny of the genus according to two DNA barcode markers was not congruent with the last morphological classifications (Hosseinzadeh-Colagar et al, 2016), and Gholamiterojeni et al (2019) performed a revision of this genus in the country using molecular ITS markers and morphological characters and recognized some new taxa.…”