Homalium rubriflorum Sleumer

Applequist, Wendy L., 2020, A revision of Homalium sect. Rhodonisa (Salicaceae) endemic to Madagascar, Candollea 75 (2), pp. 245-268 : 264-265

10. Homalium rubriflorum Sleumer

in Bull. Jard. Bot. Natl. Belg. 43: 302. 1973.

Lectotypus (designated here): MADAGASCAR. Reg. Alaotra-Mangoro [Prov. Toamasina]: Analamazaotra, Perinet , 9.III.1954, fl., Service Forestier 8365 ( P [ P00375175 ]!; isolecto-: G [ G00341927 ] image seen, L [ L0011009 ] image seen, MO-2818814 !, P [ P04734390 , P04734382 ]!, PRE [ PRE0594538-0 ] image seen, TEF [ TEF000234 ] image seen) .

Tree to 35 m tall, 80 cm dbh; bark reddish, caducous in plaques; twigs light brown, minutely pubescent to glabrous. Leaves elliptical to broadly (narrowly) elliptical, (4.5–)5.5–16 × 2.1–5.5(–8) cm, thin-textured; margin subentire, often slightly undulate, to crenulate-serrulate; base convex (rounded); apex acuminate to cuspidate (acute, obtuse, rounded or emarginate); both surfaces glabrous (seldom sparsely appressed-pubescent, mostly on midrib abaxially), drying brown abaxially, dark brown to blackish adaxially (rarely greenish); secondary veins slightly prominent; petiole 4–8(–10) mm, glabrous (sparsely minutely pubescent). Inflorescences sometimes partly terminal, longbranched peduncles (reduced to racemes), (3.7–)6–16(–20) cm; peduncle 0.6–2.4(–3.2) cm; rachis short-pubescent; flowers 1–2 per node; pedicels (1–)1.4–3(–5) mm, short-pubescent (sometimes densely). Flowers 5-merous, red; sepals oblong-ovate to oblong, 0.7–1.3 mm, sparsely appressed-pubescent outside, margins minutely ciliate; sepal glands irregularly broadly elliptical, 0.3–0.5 × 0.3 mm; calyx cup short-pubescent; petals obovate, 2.4–4 mm, little accrescent, sparsely appressed-pubescent on outer surface mostly towards base, margins ciliate; filaments 0.3–0.6 mm; anthers biglobose, c. 0.1 mm high.

Vernacular names. – “Zahana” (Cours 4437); “Zanahy” (Service Forestier 26); “Zandambo” (Service Forestier 9779, 28753).

The wood is reported to be very hard and used in construction (Cours 4437).

Distribution, ecology and conservation status. – Homalium rubriflorum is native to mid-elevation humid forests in the Alaotra-Mangoro region of northeastern Madagascar. The EOO is estimated as 5612 km ², and the AOO as 32 km ². As few as four clearly distinct populations have been collected. Two of these, which supply almost all of the collections, have been widely distributed in the protected areas of Analamazaotra or Perinet (now Andasibe-Mantadia) and Zahamena.

Therefore, the species is not expected currently to be experiencing severe declines in available habitat, and its conservation status is estimated as “Least Concern” [LC]. However, it is of concern that the only recent collections have been from a single area, that of Zahamena.

Notes. – Sleumer saw two duplicates of the type collection at P [ P00375175 , P04734390 ]. Both sheets were marked by Sleumer as “ holotype ”, but only the former is treated as a type by the Paris herbarium. Since Sleumer did not distinguish between these two sheets in labeling or in print, they are to be treated as syntypes (Art. 40, Note 1 of the ICN; TURLAND et al., 2018) and one should be chosen as lectotype. The sheet previously labeled as the type is herein designated as lectotype because it is a better specimen and has both the original collector’s label and additional material in a fragment packet.

Additional material examined. – MADAGASCAR. Reg. Alaotra-Mangoro [Prov. Toamasina]: d’Andasibe à Andapabe, 900 m, 16.III.1951, fl., Cours 4437 ( P [2 sheets]) ; Ambatovola, I.1928, fl., Perrier de la Bâthie 18411 ( P [2 sheets]) ; Parc National de Zahamena , Vohitsingitry, 17°39'31"S 48°39'20"E, 1085 m, 21.II.2000, fl. & fr., Rakotonandrasana et al. 401 ( MO, P) ; Parc National de Zahamena , Ankosy, piste vers Bemoara, 17°28'58"S 48°44'10"E, 997 m, 14.VII.2000, fl., Rakotonandrasana et al. 420 ( MO, P) ; Im[er]imandroso , Ambatondrazaka, 16.IV.1956, fl., Réserves Naturelles 8712 ( P) ; Analamazaotra, s.d., fl. & fr., Service Forestier (Louvel) 26 ( P) ; Ambatomasina, Antandrokomby , 15.III.1954, fl., Service Forestier 9779 ( MO [2 sheets], P [2 sheets]) ; Versant W du Massif de l’Ampahana , à l’E de Fierenena ( Moramanga ), 950–1300 m, 10–16.III.1969, fl., Service Forestier 28753 ( P [2 sheets]).