Linderniaceae on inselbergs in Madagascar

Linderniaceae play an important role in the vegetation of granitic or gneissic inselbergs. Linderniella pygmaea (Bonati 1924b: 107) Fischer, Schäferhoff. & Müller (2013: 228) (≡ Craterostigma pygmaeum Bonati) is an endemic species from Central Madagascar (Andringitra massif, Horombe Plateau and Ambatolampy) growing in Coleochloa setifera mats together with Xerophyta dasylirioides Baker (1875: 235), X. pinifolia Lam. ex Poiret (1808: 804) and Pachypodium densiflorum Baker (1887: 503) . The species is desiccation tolerant. Linderniella cerastioides (Bonati 1924b: 106) Fischer, Schäferhoff & Müller (2013: 227) (≡ Craterostigma cerastioides Bonati) is also an endemic species restricted to the Andringitra massif and growing in Coleochloa setifera mats on granitic inselbergs accompanied by Xerophyta dasylirioides, X. pinifolia and several succulents (e,g. Pachypodium densiflorum). It is also a desiccation-tolerant taxon. Linderniella horombensis (Fischer 1995: 238) Fischer, Schäferhoff & Müller (2013: 227) (≡ Lindernia horombensis Eb.Fisch.) is another resurrection plant found in Coleochloa setifera mats accompanied by Xerophyta dasylirioides, X. pinifolia, Linderniella pygmaea and several succulents. It is endemic to the Horombe Plateau SW of Ambalavao. The recently described Linderniella porembskii Andriamiar. & Rabarim. in Andriamiarisoa et al. (2023: 12) is morphologically very close to L. horombensis and probably merits only a varietal status. The only other Linderniaceae species endemic to Madagascar, Crepidorhopalon microcarpaeoides (Bonati 1924a: 101) Fischer (1995: 252) (≡ Lindernia microcarpaeoides Bonati), is an annual species occurring in ephemeral flush vegetation in Central Madagascar. Occasionally, the endemic Lindernia lemuriana Fischer, Schäferhoff & Müller (2013: 225) and Lindernia viguieri (Bonati 1926: 3) Fischer (1995: 240), both annual species, are found in ephemeral flush vegetation, but they also occur in anthropogenic habitats like rice fields (Fischer 1995, Fischer 2023). As the inselbergs in Northern Madagascar have not been studied by Rabarimamanarivo et al. (2019), no data on endemic Linderniaceae are available from this area and Lindernia barthlottii is the first record in this region.