Homalium analavelonae Appleq., 2020

Applequist, Wendy L., 2020, A revision of Homalium sect. Rhodonisa (Salicaceae) endemic to Madagascar, Candollea 75 (2), pp. 245-268 : 251

2. Homalium analavelonae Appleq. , sp. nov.

( Fig. 3 ).

Holotypus: MADAGASCAR. Reg. Atsimo-Andrefana [Prov. Toliara]: forêt d’Analavelona au N du Fiherenana, 950–1250 m, III.1934, fl., Humbert 14236 ( P [ P04679164 ]!; iso-: G [ G00341928 ] image seen, P [ P04679167 , P04679171 , P04679172 ]!).

Homalium analavelonae Appleq. differs from H. albiflorum (Boivin ex Tul.) O. Hoffm. in its short peduncles, villous rachises, and usually larger anthers.

Tree to 12 m tall; twigs dark gray, glabrous. Leaves broadly elliptical to elliptical or broadly obovate, 5.4–12.2 × 3–7.5 cm, relatively thin-textured; margin shallowly or inconspicuously crenulate; base rounded (convex); apex cuspidate to emarginate (rounded-obtuse); both surfaces glabrous, drying greenish to pale brown, sometimes discolored adaxially; secondary veins somewhat prominent; petiole 11– 21 mm, glabrous. Inflorescences racemose, immature 2–4 cm with possibly zigzag rachis; peduncle 0.2– 0.6 cm; rachis villous; flowers 2–3 per node; pedicels 1–2 mm, pilose. Flowers probably 4–5-merous, white; sepals in early flower oblong-ovate to oblong-lanceolate, 1.5–1.7 mm, sparsely pubescent with few long appressed hairs outside, inside sometimes glabrate, margins long-ciliate; sepal glands c. 0.4 × 0.3 mm; calyx cup pilose; petals obovate, in early flower 3 – 3.7 mm, accrescence unknown, sparsely appressed-pubescent with sometimes long trichomes on both surfaces, margins short-ciliate; filaments 0.6–0.8 mm; anthers broadly elliptical, 0.3 mm high.

Distribution, ecology and conservation status. – Homalium analavelonae is known only from one collection from the southwestern massif of Analavelona ( Fig. 2 ). Analavelona is a sacred forest and has some level of protection. Because this forest is subhumid, while forests in surrounding areas are dry (and highly degraded or lost), the species is unlikely to occur anywhere else.

This means that the species is vulnerable to having its entire population affected by a single event, so a preliminary assessment of its conservation status is “Vulnerable” [VU D2].

Notes. – Homalium analavelonae is presumed to be closely related to H. albiflorum s.str. That species has elliptical to broadly elliptical (or rarely ovate or narrow) leaves, longer racemes with well-developed peduncles and pubescent indument, and usually smaller transversely elliptical anthers (especially in its southern distribution). Its pedicels and calyx are usually pubescent (though rarely pilose) and the indument on the petals sometimes moderately dense but short. Many leaves of the type collection of H. analavelonae are damaged or irregularly shaped.

Figures

Fig. 3. – Homalium analavelonae Appleq. A. Flowering branch; B. Inflorescence; C. Inflorescence nodes with flowers before full anthesis. [Humbert 14236, P] [Drawings: R.L. Andriamiarisoa]

Fig. 2. – Map of representative distributions of species in the Homalium albiflorum complex, approximated as necessary.