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| Acorus shannai C.L.Long & Z.Cheng, in Cheng, Liu, Yu, Chen, Zhao, Li et Long, 2025. |
Abstract
Acorus shannai (Acoraceae) is a commonly used seasoning in southern China. It was previously misidentified as A. macrospadiceus (Yamam.) F. N. Wei & Y. K. Li before. Through comparison of morphological characteristics, distribution locations, and type specimen, we determined that the elevation of A. gramineus var. macrospadiceus Yamam to species status was incorrect. Therefore, we propose a formal description of a new species following nomenclature regulations. Based on morphological and plastid genomic data, this study formally describes and illustrates Acorus shannai, distributed in the Qiandongnan area of Guizhou Province and its surroundings, confirming it as a new species within the genus Acorus. This species is morphologically and phylogenetically distinct from other members of the A. gramineus group. Key distinguishing features include a strong fennel odor (vs. aromatic in “A. tatarinowii” and A. gramineus), fruit with prominent dorsal sutures (vs. inconspicuous dorsal sutures in “A. tatarinowii” and A. gramineus), and a leaf-shaped spathe that is about 2–3 times as long as the spadix (vs. more than 3 times in “A. tatarinowii”). Phylogenetic analysis showed that A. shannai is closely related to the other species in the A. gramineus group. The recognition of A. shannai is not only important for the species diversity and phylogenetic relationship of Acorus, but also can avoid the drug safety caused by using other Acorus species as A. shannai to eat and promote the conservation of A. shannai resources.
Key words: Acorus gramineus var. macrospadiceus, Acorus macrospadiceus, Guizhou Province, new taxon, taxonomy
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| Acorus shannai C.L.Long & Z.Cheng, sp. nov. A plant inflorescence stage B whole plant C species habitat D rhizome and fibrous roots E petiole leaf F inflorescence and bract G, H inflorescence I fruit —photos by Zhuo Cheng. |
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| Acorus shannai C.L.Long & Z.Cheng, sp. nov. A whole plant in infructescence stage B fruit C infructescence Drawn by Xinchen Qu. |
Acorus shannai C.L.Long & Z.Cheng, sp. nov.
“山柰菖蒲”(Shan Nai Chang Pu)
Diagnosis: The strong fennel aroma of the plant, distinct dorsal sutures on the fruit, and a spathe length 2–3 times that of the spadix are diagnostic features that differentiate A. shannai from other species in the A. gramineus group. The new species belongs to the A. gramineus group based on the following characteristics: Leaves without conspicuous marginal swellings of the lamina and a distinct midrib (Li 1979). According to the key to the species of Acorus occurring in China (Li 1979; Li et al. 2010), the morphology of A. shannai is similar to “A. tatarinowii” and A. gramineus. However, A. shannai can be clearly distinguished by the following features: the whole plant emits a strong fennel odor (vs. aromatic in “A. tatarinowii” and A. gramineus), the fruit has distinct dorsal sutures (vs. inconspicuous dorsal sutures in “A. tatarinowii” and A. gramineus), and the leaf-shaped spathe is approximately 2–3 times longer than the spadix (vs. more than 3 times in “A. tatarinowii”).
Etymology: The specific epithet is derived from the local name “shannai”.
Zhuo Cheng, Xinyu Liu, Nianting Yu, Weizhe Chen, Haofeng Zhao, Feifei Li and Chunlin Long. 2025. Acorus shannai (Acoraceae), A New Species from Southern China. PhytoKeys. 251: 175-188. DOI: doi.org/10.3897/phytokeys.251.139141
