Hibiscus involucratus (Hochr.) M. Hanes, G.E. Schatz & Callm., 2020

Hanes, Margaret M., Schatz, George E. & Callmander, Martin W., 2020, Transfer of the Malagasy genera Humbertianthus and Macrostelia to Hibiscus (Malvaceae) with description of four new species, Candollea 75 (2), pp. 193-202 : 196

Hibiscus involucratus (Hochr.) M. Hanes, G.E. Schatz & Callm. , comb. nov.

 Macrostelia involucrata Hochr. in Notul. Syst. (Paris) 14: 230. 1952.

Holotypus: MADAGASCAR. Reg. Atsimo-Atsinanana [Prov. Fianarantsoa]: Vondrozo, [22°49'S 47 °19'E], 11.IX.1926, fl., Decary 5257 ( P [ P00037126 ]!; iso-: G [ G00014442 ]!, P [ P00365083 , P00037127 ]!, TEF) .

Distribution and ecology. – Hibiscus involucratus is known from the low elevation tropical evergreen forests around Vondrozo at c. 450 m elevation ( Fig. 2 ).

Conservation status. – Hibiscus involucratus is known only from a single location near Vondrozo, collected in 1926. It is possible that the collection has been made in what is now known as the Ambositra-Vondrozo protected area. With a single collection in the low elevation moist evergreen forests, which are highly threatened in Madagascar, this species is assigned a conservation status of “Critically Endangered” [CR B2ab(iii)] using the IUCN Red List Categories and Criteria ( IUCN, 2012).

Notes. – Hibiscus involucratus can be distinguished from all other pendent Hibiscus in Madagascar by its tubular epicalyx with 6 irregular teeth that completely hides the calyx.

We consider the sheet [P00037126] as the holotype, as it is the only specimen with Hochreutiner’s handwriting in P.

Figures

Fig. 2. – Known distribution of the seven species of Hibiscus L. highlighted in this paper.