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| Cladopus yangjiangensis X.T.Liu, G.Di Chen & B.Hua Chen, in Zhang, Liu, Tian, Z.-X. Chen, Huang, G.-D. Chen et B.-H. Chen. 2024. |
Abstract
This paper introduces Cladopus yangjiangensis, a newly identified species that enriches our understanding of the diversity of the Podostemaceae in East Asia. Distinctive in its morphological traits, this species is characterized by the region’s longest flowering shoots and exhibits a high number of elongated leaves per cluster, along with relatively slender roots. Phylogenetic analyses using Maximum Likelihood and Bayesian Inference methods on plastome and matK sequences confirm C. yangjiangensis as a distinct species. It forms a clade with C. fukienensis, its closest relative, together branching off from C. austrosinensis. The plastome of C. yangjiangensis is 132,818 bp in length, comprising two inverted repeat regions of 20,881 bp, which are separated by large and small single-copy regions of 78,713 and 12,343 bp, respectively. Genetic analysis reveals the extensive loss of the ycf1 and ycf2 genes in the chloroplast genome, a trait common to the Podostemaceae, suggesting adaptations to environmental conditions or gene transfers to nuclear or mitochondrial genomes. This study improves the clarity of phylogenetic relationships in previous studies and underscores the importance of continued taxonomic and phylogenetic research.
Key words: Biodiversity, chloroplast genome, morphology, phylogeny, Podostemaceae
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| Cladopus yangjiangensis A flowering shoot on roots, inverted tower shape (reproductive leaves (a.k.a. bracts) imbricate, finger-like) a flower with 2 stigmas, a stamen (stamen clearly longer than ovary) B stamens, arrow points to two tepals, fused to ovary C gynoecia, arrow points to reddish, ribbon-shaped stigmas D stamen and tepals (tepals attached to filament bases on either side) E stamen F gynoecium with ellipsoid ovary, no bracts G longitudinal ovary section H ovules. Scale bars: 2 mm (A); 500 μm (A, B, C, D, E, F, G); 200 μm (H). |
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| Cladopus yangjiangensis A habitat (Photographed by Guo-Di Chen) B root with tufts of leaves, leaves linear, brick red in color C plants in bud adhering to rock surface D flowering shoot E top view of flower (red arrow pointing to the stamen) F mature fruits. |
Cladopus yangjiangensis X.T.Liu, G.Di Chen & B.Hua Chen, sp. nov.
Diagnosis: Cladopus yangjiangensis shares certain similarities with C. fukienensis and C. austrosinensis, such as comparable ovary lengths, and analogous stigma and capsule shapes. However, it is distinguished by several unique traits. The leaves of C. yangjiangensis are markedly elongated, measuring 18.7–26.7 mm, which is substantially longer than those of C. fukienensis (1.3–5.0 mm) and C. austrosinensis (up to 6 mm). The flowering shoots of C. yangjiangensis also exceed those of other two species, ranging from 4.2 to 13.1 mm, compared to 3.5–6.0 mm in C. fukienensis and 1.6–3.5 mm in C. austrosinensis. Additionally, C. yangjiangensis produces a greater number of bracts, with counts ranging from 20 to 54, in contrast to 12–36 in C. fukienensis and 8–14 in C. austrosinensis. Finally, the root width of C. yangjiangensis is notably narrower, at about 0.4 mm, compared to 0.4–1.3 mm in C. fukienensis and 0.5–1.3 mm in C. austrosinensis (Table 3).
Etymology: The epithet yangjiangensis (阳江) refers to Yangjiang City, Guangdong Province, South China, where this new species was found.
The Yang Jiang Chuan Tai Cao (阳江川苔草).
Miao Zhang, Xiu-Ting Liu, Min Tian, Zhang-Xue Chen, Ying-Lin Huang, Guo-Di Chen and Bing-Hua Chen. 2024. Cladopus yangjiangensis (Podostemaceae), A New Species from Guangdong, South China, redefining the phylogenetic relationships within Cladopus. PhytoKeys. 249: 231-249. DOI: doi.org/10.3897/phytokeys.249.140342
