Reinstatement of Lappula betpakdalensis (Boraginaceae) based on phylogenomic and morphological evidence

Lappula lasiocarpa is highly distinctive and easily distinguished from other congeners within Lappula owing to its saccate nutlet wings with entire margins densely covered in pubescence. Following the taxonomic revision of Lappula, the Flora of China treated L. betpakdalensis as a synonym of L. lasiocarpa. However, a comparison of the type specimens of these two taxa reveals clear morphological differences.

Although both species produce distinctly winged nutlets, the wings of L. betpakdalensis are dentate, whereas those of L. lasiocarpa are entire and densely pubescent along their margins. These striking differences in nutlet morphology cast doubt on their conspecific status. In the present study, phylogenomic analyses based on chloroplast genomes and Angiosperms 353 datasets placed both L. betpakdalensis and L. lasiocarpa within the same major clade (Clade Fa in the chloroplast phylogeny and Clade VIIb in the nuclear phylogeny), together with their close relatives L. macrantha, L. semiglabra, and L. pavlovii.

Nevertheless, within this clade, L. betpakdalensis forms a strongly supported independent lineage distinct from L. lasiocarpa (LPP = 1.00, BS = 100). Furthermore, morphological comparisons confirmed that, in addition to the contrasting nutlet wing margins (entire vs. dentate), corolla size is another key diagnostic character distinguishing the two species. Specifically, L. betpakdalensis has a corolla 3–4 mm in diameter, whereas that of L. lasiocarpa measures 5–6 mm.

Taken together, the phylogenomic and morphological evidence does not support the synonymization of L. betpakdalensis under L. lasiocarpa. Accordingly, L. betpakdalensis is reinstated as a distinct species.