Hedysarum langranii sp. nov. (Fabaceae, Hedysareae), a New Species From China, and Supplementary Descriptions of H. smithianum and H. dentatoalatum

TL;DR

A new Hedysarum species from China is described, along with updated details for two related species, based on physical and genetic differences.

Contribution

A new Hedysarum species is identified and distinguished through morphological and phylogenetic analysis.

Findings

H. langranii differs from H. smithianum in several morphological traits like petal and loment sizes.

H. langranii is distinct from H. dentatoalatum by leaflet texture, corolla color, and loment features.

Phylogenetic trees based on nuclear and plastid sequences show conflicting relationships for H. langranii and H. dentatoalatum.

Abstract

Hedysarum langranii sp. nov. (Fabaceae, Hedysareae) is described and illustrated from Shaanxi, Henan and Gansu, China. This new species is morphologically similar to H. smithianum, but can be distinguished by its glabrous stipules (vs. sparsely pubescent), standard petal 9–11 mm long (vs. 12–13 mm long), keel petals 12–13 mm long (vs. 14–15 mm long), androecium 13–15 mm long (vs. 16–17 mm long), loment articles 4–5 mm wide (vs. 5–7 mm wide). The new species can be easily distinguished from H. dentatoalatum by its papyraceous leaflets (vs. membranaceous), corolla pale purple or pink (vs. pale yellow); loment articles 5–7 × 4–5 mm, without prickle on the veins, with minute irregular teeth along both sutures (vs. 8–12 × 10–12 mm, with prickles on the veins, with wings and prominent teeth along both sutures). The phylogenetic tree based on the nuclear sequences shows that H. langranii is sister to H. dentatoalatum, while the tree based on the plastid sequences shows that H. langranii is sister to a clade consisting of H. smithianum and H. dentatoalatum. The new species and H. dentatoalatum are both diploids with a chromosome number 2n = 14. Supplementary descriptions of H. smithianum and H. dentatoalatum are also provided. The incongruent phylogenetic position of H. dentatoalatum could be explained by an ancient hybridization hypothesis, but requires further investigation to determine the reason for this incongruence.

Hedysarum langranii sp. nov. (Fabaceae, Hedysareae) is described from China based on morphological and phylogenetic evidence. Supplementary morphological descriptions of H. smithianum and H. dentatoalatum are provided.

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