Revision of the Malagasy species of Homalium sect. Eumyriantheia Warb. (Salicaceae)
Wendy L. Applequist
Candollea
2016
2016-03-14
71
1
33
60
3MCKM
Appleq.
Appleq.
[852,1128,1405,1429]
Magnoliopsida
Salicaceae
Homalium
Plantae
Malpighiales
6
39
Tracheophyta
species
dorrii
sp. nov.
( Fig. 1, 2A).
Typus: Madagascar. Prov. Toamasina: Analalava, 2.8 kmWof old fortress at Foulpointe, 3.XII.1985, fl., Dorr et al.4432(holo-: MO-3320333!; iso-, P [P04705567, P04705569]!).
Homalium dorrii Appleq.differs from H. maringitra H. Perrierin having narrowly obovate to narrowly elliptic leaves with cuneate to convex bases, subopposite or clustered near twig ends, and longer sepals.
Treeto 10-15 mtall, 6 cmdbh; large twigs dark or grayish brown; young twigs gray-brown to pale whitish gray, glabrous; stipules deltoid, 1 mm, glabrous. Leavesclustered at twig apices or on short branches or subopposite, leaf scars on older twigs occasionally whorled; petiole 5-11 mm, glabrous; blade narrowly obovate to narrowly elliptic or oblong-elliptic or obovate, 4.2-9 × 1.6-4 cm; base convex to cuneate; apex rounded; margins slightly revolute, shallowly and irregularly denticulate with few teeth, glands located in teeth; abaxial surface glabrous, drying brown; adaxial surface glabrous, drying dark brown. Inflorescencesracemose, lateral, often clustered near twig apices, 4.5-9 cm, sparsely short-pubescent (to moderately pubescent distally); peduncle 0.3- 4 cm, moderately thick; pedicel 1-4 mm, short-pubescent; bracts very few, deltoid, 0.5-1 mm, minutely pubescent; bracteoles not seen (absent or caducous and not leaving obvious scars). Flowerssepals 4-5, broad-based obovate to nearly oblong with rounded apex, 3.7-4.6 mm, abaxial surface moderately (sparsely) shortpubescent on basal half, sparsely pubescent toward apical margin; calyx cup funnelform (becoming convex in fruit), ridged, shortpubescent; sepal glands roughly elliptical, 1-1.2 × 0.5-0.6 mm, upper surface densely short-pubescent; petals white or whitish-grey, obovate with rounded apex, 4.8-5.4 × 2-2.6 mm, moderately longer than sepals, abaxial surface short appressed-pubescent mostly at base and in center, adaxial surface glabrous; filaments ca. 1-1.5 mm, glabrous; anthers 0.3 mm; ovary conic (becoming hemispherical in fruit), short-pubescent; styles 4, ca. 1 mm, basally short-pubescent. Seeds1 per fruit, subglobose, 2-2.5 mm.
Distribution, ecology and conservation status. –The two known collections of H. dorriiare from the forest of Analalava near Foulpointe, at a low elevation near the coast, on laterite. The small number of collections suggests that the species is rare, since the area around Foulpointe was repeatedly botanized over several decades. Though the location had until recently been subject to ongoing degradation, it is now effectively protected. Thus, given the lack of knowledge regarding this species, a preliminary conservation status of “Data Deficient” [DD] seems most appropriate.
Homalium dorriiis presumed to be most closely related to H. maringitraand the newly described H. ranomafanicum, which have generally similar floral morphology (small flowers with sparse sepal indument but dense sepal gland indument). Both of those species have usually broader, elliptic to broadly obovate or obovate, at least partly alternate leaves and short sepals (to 3.5 mmin H. maringitra) that are often barely more than half as long as the petals; both are native to mid-elevation humid forests. Homalium dorriimust also be distinguished from H. oppositifolium, which is found in eastern littoral forests and has often similarly shaped leaves and densely pubescent sepal glands. Homalium oppositifoliumhas a densely (to moderately) pubescent perianth, as well as denser and longer pubescence on the rachis and pedicels and sometimes on the petiole and leaf midrib; the sepals are 5-6 innumber and often narrow, and the bracts and bracteoles more numerous and sometimes quite large.
Paratypus. – Madagascar. Prov. Toamasina: Fkt. Morarano, forêt d’Analalava, à 7 kmdu SWde Foulpointe, 17°42’32”S 49°27’33”E, 43 m, 8.III.2005, post-fl., Birkinshaw et al.1434( P[ P04734868]).
1985-12-03
MO
Dorr et al.
Madagascar
Foulpointe
Analalava
6
39
MO-3320333
1
Toamasina
holotype
3461735480
6
39
3461735332
2005-03-08
P
Birkinshaw et al.
Madagascar
43
-17.708889
Foulpointe
21
49.459167
Fkt. Morarano
8
41
1
Toamasina
paratype