Integrative analyses ofCrepidium(Orchidaceae, Epidendroideae, Malaxideae) shed more light on its relationships withDienia,LiparisandMalaxisand justify reinstatement of narrow endemicC. allanii

Abstract

Malaxidinae are a cosmopolitan higher Epidendroid subtribe of > 1250 species that exhibit wide morphological and ecological diversity. Despite almost two centuries of taxonomic deliberation, controversy persists regarding the delimitation of practically all Malaxidinae genera, the most important of which are Crepidium, Dienia, Liparis and Malaxis. Previous attempts to classify these genera using a molecular phylogenetic approach showed Liparis and Malaxis to be polyphyletic and the floral characters traditionally used to define them as homoplastic. Emphasis has instead shifted to vegetative and ecological traits. Here, we conduct an expanded analysis of nuclear (ITS) and plastid (matK) sequences focused on terrestrial taxa, with the resulting phylogram largely corroborating the emerging picture, and we test the efficacy of four previously highlighted traits to recover the same relationships. Although growth habit is underscored as important for resolving a natural distinction between epiphytic Liparis and terrestrial ‘Crepidium clade’ plus ‘Malaxis clade’ taxa, leaf shape and venation and habitat preference are shown to be poor predictors of phylogenetic affiliation. Instead, perennating organ structure (heteroblastic or homoblastic) and placement (predominantly above- or below-ground) – are incisive, with leaf number and texture apparently correlated. These findings are discussed in the context of an inferred evolutionary history of the subtribe. Although homoplastic at the subtribe level, some floral characters are shown to be useful for resolving identities at the species level. Accordingly, the status of four long-confused species (Crepidium acuminatum, C. allanii, C. purpureum and Microstylis biloba) is resolved.

Liparis macrosepala (Orchidaceae), a new species from southwest China with its phylogenetic position

“…The phylogenetic analyses indicate that Liparis is not monophyletic, being mingled with species of other genera of Malaxideae. This result agrees with what was found in previous studies (Cameron 2005;Margońska et al 2012;Tang et al 2015;Li et al 2020;Kumar et al 2022). The new species, henceforth referred to as Liparis macrosepala Z.W.…”

Seidenfia manikathila (Orchidaceae, Epidendroideae, Malaxideae), a new species from south Western Ghats, India

“…Critical analysis of the literature (Szlachetko 1995;Margońska & Szlachetko 2001;Margońska 2005Margońska , 2007Margońska et al 2012Margońska et al , 2015Sasidharan 2013;Kumar et al 2021), as well as the scrutiny of vouchers deposited in K, NY, PE, MH, CAL, TBGT and CUBH were done. The data presented were obtained through the study of live specimens in the wild, available herbarium materials, and an in-depth literature survey.…”

Gains and losses of the epiphytic lifestyle in epidendroid orchids: review and new analyses with succulence traits

“…In Calypsoeae and Bletiinae, this stem succulence takes the form of underground corms, while in Malaxideae, Collabieae and Eulophiinae it is pseudobulbs (Pridgeon et al, 2005(Pridgeon et al, , 2009. However, pseudobulbs are sometimes more or less buried, for example in Collabieae genus Ipsea (Pridgeon et al, 2005;Descourvières, 2011), or in better protect them from above-ground temperatures extremes and drought, especially in seasonal climates (Pemberton et al, 2008;Kumar et al, 2022). In addition, Kumar et al (2022) showed that some species in Malaxideae are secondary epiphytes, and that they also retained the perennating organ structure and leaf texture of their parent lineage.…”

“…However, pseudobulbs are sometimes more or less buried, for example in Collabieae genus Ipsea (Pridgeon et al, 2005;Descourvières, 2011), or in Eulophia graminea (Pemberton et al, 2008). Actually, burying succulent structures could better protect them from above-ground temperatures extremes and drought, especially in seasonal climates (Pemberton et al, 2008;Kumar et al, 2022). In addition, Kumar et al (2022) showed that some species in Malaxideae are secondary epiphytes, and that they also retained the perennating organ structure and leaf texture of their parent lineage.…”

“…However, pseudobulbs are sometimes more or less buried, for example in Collabieae genus Ipsea (Pridgeon et al, 2005;Descourvières, 2011), or in better protect them from above-ground temperatures extremes and drought, especially in seasonal climates (Pemberton et al, 2008;Kumar et al, 2022). In addition, Kumar et al (2022) showed that some species in Malaxideae are secondary epiphytes, and that they also retained the perennating organ structure and leaf texture of their parent lineage. This tends to support the hypothesis that seasonal forests could have been the cradle to at least part of both epiphytes and terrestrial Epidendroideae diversity.…”