Hibiscus retrobracteatus (Hochr.) M.M. Hanes & Callm.

Hanes, Margaret M., Mashburn, Brock & Callmander, Martin W., 2022, Transfer of the endemic Malagasy species of Kosteletzkya to Hibiscus and Perrierophytum (Malvaceae), Candollea 77 (2), pp. 161-171 : 162-163

Hibiscus retrobracteatus (Hochr.) M.M. Hanes & Callm. , comb. nov. (F ig. 2).

Kosteletzkya retrobracteata Hochr. in Mém. Soc. Hist. Nat. Afrique N., Hors Sér. 2: 157. 1949.

Lectotypus (designated here): MADAGASCAR. Aeg. DIANA [Prov. Antsiranana]: forêt d’Analamera [Analamerana], 17.X.1927, Ursch 148 (P [ P034489 ]!; isolecto-: G [ G00014373 ]!, P [ P034463 ]!).

Vernacular name. – “Mainaty” (Service Forestier 9422).

Distribution and ecology. – Hibiscus retrobracteatus is restricted to the dry deciduous forest (sensu GAUTIER et al., 2018) of northern Madagascar. It grows in the regions of Ankarana, Analamerana, Sahafary plateau, and LokyManambato (Daraina) (F ig. 3).

Conservation status. – Hibiscus retrobracteatus (under Kosteletzkya retrobracteata ) is listed as “Endangered” [EN B1ab (i,ii,iii,iv)+2ab(i,ii,iii,iv)] in the IUCN Red List (IUCN, 2022) and The Red List of Trees of Madagascar (BEECH et al., 2021).

Notes – Hochreutiner’s handwriting on G00014373 and P034489 attests that he was unsure whether to describe this species in Hibiscus or in Kosteletzkya . Gross morphology clearly shows that this species belongs to Hibiscus .

Hibiscus retrobracteatus is distinctive among Malagasy Hibiscus species due to the unique combination of six small (2– 5 mm), free, triangular, glabrous, epicalyx bracts that are reflexed tightly against the peduncle (F ig. 2B).

HOCHREUTINER (1949: 157) cited the type as “ Hb. Mus. Paris et G ”. The best-preserved material of Ursch 148 is at P [ P034489 ] and designated here as the lectotype .

Additional specimens examined. – MADAGASCAR. Aeg. DIANA [Prov. Antsiranana]: massif de l’Ankarana , 12°54'S 49°08'E, 10.XI.1990 & 20.III.1991, fr., Bardot-Vaucoulon 140 ( P [ P00574032 ]) ; ibid. loco, 19.I.1991, ster., Bardot-Vaucoulon 394 ( P [ P00569734 ]) ; ibid. loco, 1.III.1991, fl., BardotVaucoulon 414 ( P [ P00553055 ]) ; ibid. loco, bordure de la rivière Ampandrabe, chem. vers le canyon forestier, 12°57'08"S 49°07'43"E, 24.III.2007, fl., BardotVaucoulon 1555 ( P [ P00643074 ]) ; Diégo, s.d., fr., Louvel s.n. ( P [ P00574801 ]) ; forêt d’Analafondro , au pied SE du plateau de Sahafary (bassin inférieur du Rodo), [12°37'S 49°29'E], 7.II.1966, fr., Service Forestier 24525 ( CANB, K, MO, P [ P00574959 ]) . Aeg. SAVA [Prov. Antsiranana]: Daraina, forêt d’Antsaharaingy , 12°54'52"S 49°39'25"E, 3.III.2005, bud, Nusbaumer 2113 ( G) ; ibid. loco, 12°54'29"S 49°40'27"E, 45 m, 16.IV.2004, fr., Ranirison 663 ( G [ G00028385 ], P [ P00653158 ]) .