[Botany • 2019] Euphorbia pseudodidiereoides (Euphorbiaceae) • A New Species from south-central Madagascar

Euphorbia pseudodidiereoides J.-P. Castillon & Rajaovelona, 

G-H) E. didiereoides 

in Castillon & Rajaovelona, 2019. 

  Researchgate.net/publication/332511734

Abstract  

A new species of spiny, multi-stemmed spurge, Euphorbia pseudodidiereoides J.-P. Castillon & Rajaovelona, is described and illustrated here. It is known only from the Ihorombe region, south central Madagascar, and occurs on an isolated quartzite massif surrounded by vast grasslands and granite inselbergs. Its presumed nearest relative is E. didiereoides Denis ex Leandri, with which it shares many common characters, including: general V-shaped habit reminiscent of some species of the genus Alluaudia (Drake) Drake (Didiereaceae), thick stems, numerous spines, rarely solitary, densely arranged, of variable size (5-25 mm), without alignment, green pubescent leaves, elliptic with a mucronate apex, without petiole but bearing a white thick mid-vein, capitate incyathescences, and pubescent peduncle. It differs from E. didiereoides by its shorter size (0.8-1.5 m vs 2-4 m for adult individuals), recumbent branches, and an incyathescence with shorter peduncle (1.5 cm instead of 8 cm), less dense cymes with fewer cyathia (8-16 cyathia instead of 20-60), and wider, rounded, 8x8 mm cyatophylls. This new species is assessed to be Critically Endangered according to IUCN Red List Categories and Criteria because it is only known from a single unprotected locality, with the number of mature individuals being less than 250 and a measurable decline in local natural habitat (CR B1 ab(iii,v) + 2 ab(iii,v); C2 a(ii)).

Key words: Euphorbia, new species, Goniostema, Ihorombe, Madagascar

 A) Sobennikoffia humbertiana, 

B-F) Euphorbia pseudodidiereoides, G-H) E. didiereoides 

Euphorbia pseudodidiereoides, J.-P. Castillon & Rajaovelona, species nova 

Diagnose: Haec planta Euphorbia didieroides affinisest sed sequentibus characteribus praecipue differt :minore statura (<1,5 m) ; longis caulibus inclinatisad terram ; capitatis inflorescentiis minus densis (8-16 cyathis contra 20-60) ; cyathorum foliis latioribusrotundatisque  

 

  

Jean-Philippe Castillon and Landy Rita Rajaovelona. 2019. Euphorbia pseudodidiereoides, une nouvelle euphorbe épineuse du Centre-sud de Madagascar [A New Spiny Spurge from south-central Madagascar] Malagasy Nature. 13: 60–64.

 http://www.vahatra.mg/volume13/MN13_03_Castillon.pdf

  Researchgate.net/publication/332511734_Euphorbia_pseudodidiereoides_une_nouvelle_euphorbe_epineuse_du_Centre-sud_de_Madagascar

[Botany • 2021] Euphorbia mbuinzauensis (Euphorbiaceae) • A New Succulent Species in Kenya from the Synadenium Group in Euphorbia sect. Monadenium

 

Euphorbia mbuinzauensis N. Wei, Mwachala, G.W. Hu & Q.F. Wang,

in Wei, Mutie, Mwachala, ... et Wang, 2021. 

DOI: 10.3897/phytokeys.183.70285

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

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.

  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