Diversity Patterns and a New Species of Dendrocalamus (Poaceae, Bambusoideae) in Yunnan, China.

To systematically investigate the diversity and distribution patterns of Dendrocalamus in Yunnan Province, we integrated field surveys, literature reviews, specimen records, and existing research data to compile and analyze the distribution of Dendrocalamus species across the region. The results revealed the following: (1) A total of 3730 valid distribution points were compiled, representing 38 taxa of Dendrocalamus (including 32 species, 3 varieties, and 3 forms), reflecting remarkably high species diversity. These account for approximately 52% (38/73) of the global species and 69% (38/55) of those recorded in China. (2) Horizontal Distribution Pattern: In terms of distribution points, Pu'er had the highest count (929), followed by Xishuangbanna (759) and Lincang (586). Honghe, Wenshan, and Dehong also showed substantial records. Regarding species richness, Xishuangbanna ranked highest with over 20 species, while Pu'er and Honghe contained 15-20 species. Yuxi and Kunming supported 10-15 species, and Baoshan, Nujiang, Chuxiong, Wenshan, Qujing, and Zhaotong each hosted 5-10 species. In contrast, Dali, Lijiang, and Diqing recorded only 0-5 species. (3) Vertical Distribution Pattern: Distribution points were predominantly concentrated in the 1000-1500 m elevation range, whereas species richness peaked in the 500-1000 m band. Both the number of distribution points and species richness were lowest at elevations above 2500 m. (4) Based on the collected 3730 distribution points, kernel density analysis and hot spot analysis (Getis-Ord Gi*) were performed in ArcGIS 10.8. Both analyses indicated that southern Yunnan (centered on Xishuangbanna and Pu'er) exhibits significant spatial clustering characteristics, identifying it as the core distribution area for Dendrocalamus species in Yunnan Province. (5) During field surveys, a distinctive new species characterized by swollen internodes was discovered. Morphological comparison and phylogenetic analysis confirmed it as a new species of Dendrocalamus and named Dendrocalamus turgidinodis C.M.Hui, M.S.Sun & J.W.Li, it is similar to D. hamiltonii, D. fugongensis, and D. sinicus, but can be easily distinguished by culm diameter 13-16 cm, intranode swollen, culm leaf sheath deciduous, culm blade erect, culm leaf ligule ca. 5 mm tall., Foliage leaf ligule 1-1.5 mm tall (vs. 1.5-2 mm). In conclusion, this study demonstrates that Yunnan Province serves as a major distribution center for Dendrocalamus, with the genus primarily distributed from the southeastern to southwestern parts of the region, and concentrated most densely in the southern area encompassing Xishuangbanna and Pu'er.