A revision of the Adenophorus Group and other glandular-leaved species of Croton (Euphorbiaceae) from northern Madagascar and Mayotte, including three new species

Kainulainen, K., B. Van Ee, H. Razafindraibe & P.E. Berry (2017). A revision of the Adenophorus Group and other glandular-leaved species of Croton (Euphorbiaceae) from northern Madagascar and Mayotte, including three new species. Candollea 72: 371–402. In English, English abstract. DOI: http://dx.doi.org/10.15553/c2017v722a15This paper provides a revision of the species of Croton L. (Euphorbiaceae) from northern Madagascar (mainly Antsiranana and northern Mahajanga Provinces) and Mayotte in the Comoros Archipelago that bear glands on the undersides of the leaves. This includes members of the Adenophorus Group as well as two species that do not belong to that group, namely Croton nudatus Baill. and Croton stanneus Baill. Croton nudatus has been a problematic name since its publication due to the leafless state of its type. We were able to match the type with material recently collected near the type locality, and we provide an amended description for this species. Croton stanneus is another previously poorly understood species, which is actually one of the most widespread species of Croton in Madagascar. We also re-evaluate species delimitations in members of the Adenophorus Group from northern Madagascar and Mayotte, and we describe three new species, Crotonmayottae P.E. Berry & Kainul., Croton orangeae Kainul. & P.E. Berry, and Croton sahafariensis Kainul. & P.E. Berry. Crotonloucoubensis Baill. is resurrected from synonymy, and nine other species names and eight varieties are reduced to synonymy under Croton adenophorus Baill., Croton loucoubensis, Croton nudatus, Croton scoriarum Leandri, Croton stanneus, or Crotontsiampiensis Leandri. Full descriptions are provided for these species as well as for Croton bathianus Leandri, another misunderstood species in the group. A key to the seven species of the Adenophorus Group and the two look-alikes from northern Madagascar and Mayotte is provided. An epitype is designated for Croton nudatus, and lectotypes are designated for Croton adenophorus, Croton bathianus, Croton loucoubensis, Croton scoriarum, Croton stanneus, and Croton tsiampiensis.Received: July 10, 2017; Accepted: August 23, 2017; First published online: September 27, 2017