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| Euphorbia mbuinzauensis N. Wei, Mwachala, G.W. Hu & Q.F. Wang, in Wei, Mutie, Mwachala, ... et Wang, 2021. |
Abstract
Euphorbia mbuinzauensis, a succulent new species of the Synadenium group in Euphorbiaceae from Makueni County, Kenya, is described and illustrated. Morphologically, it is most similar to E. pseudomollis, but differs mainly by its shrubby habit (up to 4 m), abaxial leaves surfaces with densely stellate hairs, 2–4-forked cymes, smaller bracts (ca. 2.5 × 3.0 mm), smaller cyathia (6 mm wide), crimson glands without narrow smooth margin, smaller fruits (ca. 8 × 7 mm) and ovoid seeds (ca. 1.8 × 2.2 mm). Furthermore, we performed a molecular phylogenetic analysis of the Synadenium group in Euphorbia sect. Monadenium, based on complete nuclear ribosomal DNA (nrDNA) datasets. This phylogenetic inference also supports it to be a distinct species. The new species is assessed as Endangered using the IUCN criteria.
Keywords: East Africa, endangered, molecular phylogeny, succulents, Synadenium, taxonomy
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| Euphorbia mbuinzauensis N. Wei, Mwachala, G.W. Hu & Q.F. Wang. A flowering branch B leaf C the close-up of abaxial leaf to show densely stellate hairs D section through leaf to show the distinct keel on midrib beneath E cyathium, lateral view F cyathium, top view G dissected involucre to show lobes H male flower and bracteole I infructescence J fruit. K. Seeds. Scale bars: 2 mm (C–H, K); 1 cm (B, I, J). Voucher specimen: SAJIT 007200. Drawn by Nan Jia. |
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| Morphological features of Euphorbia mbuinzauensis N. Wei, Mwachala, G.W. Hu & Q.F. Wang. A habit B adaxial surface of leaf C abaxial surface of leaf D a branch with numerous infructescences E apical portion of flowering branch F, G Cyathium H seeds. Scale bars: 2 mm (F–H); 2 cm (B–E). Voucher specimens: SAJIT 007411 (A), SAJIT 007200 (B–H). Photos by Neng Wei. |
Euphorbia mbuinzauensis N. Wei, Mwachala, G.W. Hu & Q.F. Wang, sp. nov.
Diagnosis: Euphorbia mbuinzauensis is most similar to E. pseudomollis, from which it differs by its shorter habit, up to 4 m (vs. to 9 m), abaxial leaves surfaces with densely stellate hairs (vs. simple hairs), 2- to 4-forked cymes (vs. 1- to 2-forked), bracts ca. 2.5 × 3.0 mm (vs. ca. 3.5 × 3.5 mm), dentate margin on bract (vs. entire or with a few teeth), cyathia 6 mm wide (vs. 8 mm wide), gland without narrow smooth margin (vs. with a narrow smooth margin), fruits ca. 8 × 7 mm (vs. ca. 10 × 10 mm), and ovoid seeds ca. 1.8 × 2.2 mm (vs. subglobose, ca. 2.5 × 2.5 mm).
Etymology: The epithet “mbuinzauensis” refers to its type locality, Mbuinzau in Makueni County, Kenya.
Notes: The conspicuous latex is extremely poisonous to cattle as well as human beings, according to the comments from local farmers. We observed ants visiting the flowers and they are a possible pollinator to this species (Figure 3G).
Neng Wei, Fredrick Munyao Mutie, Geoffrey Mwachala, Olwen M. Grace, Guang-Wan Hu and Qing-Feng Wang. 2021. Euphorbia mbuinzauensis, A New Succulent Species in Kenya from the Synadenium group in Euphorbia sect. Monadenium (Euphorbiaceae). PhytoKeys. 183: 21-35. DOI: 10.3897/phytokeys.183.70285