Hibiscus calyculatus (Hochr.) M. Hanes, G.E. Schatz & Callm., comb. nov. (Fig. 1A).  Macrostelia calyculata Hochr. in Notul. Syst. (Paris) 14: 232. 1952. Holotypus: MADAGASCAR. Reg. Haute Matsiatra [Prov. Fianarantsoa]: vallée Ampamaherana, [21°19'S 47°19'E], [1300 m], 25.V.1949, fl., Service Forestier 2046 (P [P00037125]!; iso-: G [G00014441]!, TEF). Vernacular name. – “Tsilaitra” (Service Forestier 2046, 14420). Distribution and ecology. – Hibiscus calyculatus grows in medium elevation moist evergreen forests east of Fianarantsoa, in the massif of Andrambovato, in the Ampamaherana valley and near Kianjavato (D. Scherberich, pers. comm.) from 1155–1300 m in elevation (Fig. 2). Conservation status. – Hibiscus calyculatus is known from 3 locations all encompassed in the Protected Area Network (Corridor Forestier Ambositra-Vondrozo and Ranofanana). Despite the very restricted Extent of Occurrence (EOO) of 12 km ² and an Area of Occupancy (AOO) of 8 km ², there appear to be no current threats to H. calyculatus. Thus, the species is assigned a conservation status of “Least Concern” [LC] using the IUCN Red List Categories and Criteria (IUCN, 2012), with the caution that this status is highly dependent on continued effective protection. [B: Rasoandriana 89; C: J. Razanatsoa 644] [Photos: A: D. Scherberich; B: P. Antilahimena; C: B. Mashburn] Notes. – Hibiscus calyculatus is distinguished from all other pendent Hibiscus on Madagascar by its four small (3–4 mm), free, reflexed epicalyx bracts and a distinctive red, tubular calyx. Additional specimens examined. – MADAGASCAR. Reg. Vatovavy-Fitovinany [Prov. Fianarantsoa]: Massif d’Andrambovato, Tolongoina, Ikongo, 21°30'58"S 47°25'36"E, 1155 m, 28.V.1998, fl., Razafimandimbison 335 (G, MO, P, TAN, TEX); Fort Carnot, Andrambovato Station Forestier, Parcelle A-16, [21°31'S 47°25'E], 28.VII.1954, fl., Service Forestier 14420 (P, TEF).

Published as part of 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, pp. 193-202 in Candollea 75 (2) on pages 194-196, DOI: 10.15553/c2020v752a4, http://zenodo.org/record/5683749