Homalium moniliforme H. Perrier
Creators: name: Applequist, Wendy L.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Salicaceae
Homalium
Homalium moniliforme

description: 6. Homalium moniliforme H. Perrier in Mém. Mus. Natl. Hist. Nat. 13: 291. 1940.
Lectotypus (designated by SLEUMER, 1973: 308): MADAGASCAR. Prov. Fianarantsoa: Vondrozo, province de Farafangana, s.d., fl., Decary 5469 (P [P04679983]!; isolecto-: K [K000231481] image seen, L [L0010965] image seen). Syntypus: MADAGASCAR. Prov. Toamasina: Tampina, 25.VIII, fr., Louvel 53 (P [P04679987]!).
Tree to 13 m tall, 30 cm dbh; young twigs moderately pubescent with minute hairs or glabrous (glabrate). Leaves: petiole 1-7(-10) mm long, glabrous (minutely pubescent); blade narrowly elliptical to elliptical (oblanceolate) or obovate to elliptical, (1.8-)2.7-6.8 × 0.7-2.6(-3) cm; base cuneate to attenuate or convex; margins serrulate to crenate-serrate, shallowly wavy or subentire, sometimes slightly revolute; apex rounded-acute to rounded (slightly acuminate, rounded-cuspidate, aberrantly emarginate). Inflorescences spicate, (2-)4-7(-10) cm long, minutely pubescent or glabrous; flowers in severalflowered glomerules, sessile; bracts transversely oblong, often irregular; bracteoles reduced to minute teeth, rapidly caducous. Flowers 6-7(-8)-merous, greenish (corolla pale yellow); sepals deltoid to ovate, 0.1-0.3 mm long; petals transversely (very broadly) ovate (very broadly oblong-ovate), 0.5-0.7(-0.8) mm long, glabrous, apex rounded (rounded-obtuse); filaments 0.2-0.4(-0.6) mm long; upper surface of ovary densely shortpubescent; styles (2-)3, 0.2-0.3(-0.5) mm long.
Notes. – Homalium moniliforme displays geographic variation in its vegetative morphology and ecological preferences. Collections from the southern provinces of Toliara and Fianarantsoa occur consistently at low altitudes on sand and have small, short-petioled, often narrowly elliptical to elliptical leaves and minutely pubescent twigs. This form extends to coastal forests in Toamasina province. Inland collections from moderate-elevation humid forests, which occur on more diverse substrates, range from Antsiranana to Toamasina provinces and rarely Fianarantsoa province. These have somewhat larger leaves that are longer-petioled and usually mostly obovate, less often elliptical; the twigs are glabrous or glabrate, rarely papillate at the extreme apices. The two geographically distinct forms are usually readily distinguishable. It therefore seems appropriate to recognize them as subspecies. The lectotype is from Fianarantsoa province at a low-moderate elevation, in a region where no other material of the species has been collected. Its morphology is somewhat intermediate between the two forms, with mostly narrow, oblanceolate leaves, and the leaves dry relatively pale, which is much more common in the small-leaved subspecies (though that is not a fully reliable character in any related group observed to date). However, it is overall more similar to material from the moderate-elevation populations, for which it would represent a substantial range extension. These populations are therefore herein recognized as subsp. moniliforme, and the coastal subspecies is described below as subsp. littoralis Appleq., to which the other syntype (Louvel 53) belongs.
The original publication of Homalium moniliforme did not explicitly cite specimens, but did enumerate the vernacular names provided on the labels of both Decary 5469 and Louvel 53, which were the only two collections cited in the Flora treatment six years later (PERRIER DE LA BÂTHIE, 1946). SLEUMER (1973) therefore termed them syntypes. That interpretation could be questioned, since they were only indirectly cited, but they are certainly original material, and he appropriately designated the P duplicate of Decary 5469 as lectotype.
Key to the subspecies of Homalium moniliforme
1. Young twigs glabrous (glabrate, minutely papillate at the apex); petiole 2-7(-10) mm long; leaf blade obovate to elliptical, narrowly elliptical, or oblanceolate, 3-6.8 × (1.1-)1.3- 2.6(-3) cm; mid- to low-elevation humid forests ................. ...................................................... 6a. subsp. moniliforme
1a. Young twigs moderately minutely pubescent; petiole 1-3 mm long; leaf blade narrowly elliptical to elliptical (oblanceolate), (1.8-)2.7-4.7(-5.6) × 0.7-1.6(-1.9) cm; littoral or low-elevation coastal forests .... 6b. subsp. littorale
description: Published as part of Applequist, Wendy L., 2018, A revision of Homalium sect. Odontolobus (Salicaceae) endemic to Madagascar, pp. 27-48 in Candollea 73 (1) on pages 35-37, DOI: 10.15553/c2018v731a4, http://zenodo.org/record/5722136