Begonia ambodiforahensis Scherber. & Duruiss., 2019

Scherberich, David & Duruisseau, Jacky, 2019, Three new species of Begonia sect. Erminea (Begoniaceae) from north-east Madagascar, Adansonia (3) 41 (7), pp. 59-67 : 62-64

Begonia ambodiforahensis Scherber. & Duruiss. , sp. nov.

( Fig. 3 )

Begonia ambodiforahensis Scherber.& Duruiss ., sp.nov.canbecompared to B.erminea with which it shares the distinct red margin and spiculiform hairs on the adaxial side of the leaf blade. It differs however by the narrowly lanceolate shape of the blade, less than 2 cm wide with an acute base, vs an elliptic-ovate blade to 8 cm wide with a broadly cordate base. The new species is also similar to B. nana but it has more leaves (10-20 vs 2-6 in B. nana ), which are proportionally longer and narrower, and the latest misses the spiculiform hairs and red margin of the lamina. It could also be compared to the narrow leaf variety of B. antongilensis ( B. antongilensis var. cuneata ), but that species has conspicuous stems to 10 cm (vs acaulous), glabrous and entire to weakly dentate leaves that typically dries dark brown while B. ambodiforahensis Scherber. & Duruiss. , sp. nov. dries yellow-green to green-brown.

TYPUS. — Madagascar. Analanjirofo region: Maroantsetra District, Tampolo , Péninsule de Masoala , Ambodiforaha , au Nord de Tampolo, 15°42’35’’S, 49°58’13’’E, 200 m, forêt dense humide, basfond, Mission Radeau des Cimes 2001, 20.X.2001, Labat et al. 3360 (holo-, P [ P00340594 ]! ; iso-, G [ G00405571 ]!, K!, MO, TAN, TEF).

PARATYPES. — Madagascar. Analanjirofo region: Maroantsetra District, Ambanizana, pente au-dessus de Tampolo , près de la limite du Parc national Masoala , “S: 15.42.180 E: 49.57.713”, 8.XI.2004, Aridy 455 ( P [ P05619949 ]!, ZT [ ZT-00162682 , ZT-00162685 , ZT-00162686 ]!) ; Ambodiforaha, sur rochers moussus le long de la rivière, 15°42’12”S, 49°58’02”E, 157 m, plant in cultivation in Lyon Botanical Garden under n°150333, originally collected by E. Bouquet and J. Duruisseau, Scherberich 1157 (LYJB!) .

DISTRIBUTION AND ECOLOGY. — Begonia ambodiforahensis Scherber. & Duruiss. , sp. nov. is only known from a small area north of Tampolo, where it can form small colonies on mossy rocks (gneiss), in proximity to rivers, in dense humid forest, at low elevation (45-200 m). Flowering has been observed from October to March but probably extends further.

CONSERVATION STATUS. — The new species has a very restricted distribution within the Masoala Peninsula, right on the margin of the Masoala National Park ( Fig. 1 ). Furthermore, satellite images observation with Google Earth indicate anthropomorphic disturbance in the area. Thus, having an area of occupancy which is less than 20 km 2, the conservation status as “Vulnerable” [VUD2] is proposed following the IUCN Red List Categories and Criteria ( IUCN 2012).

DESCRIPTION

Tuberous perennial lithophytic herb, acaulescent.

Tuber

Small, 10-20 mm, irregular, strongly adherent.

Stem

Absent or very short, to 5 mm.

Stipules

Persistent, the margins entire.

Leaves

Numerous, usually 10 to 20, alternate, straight, spreading to pendent; lamina and petiole sparsely minutely orange brown glandular dotted; petiole 1.1-5.5 cm long, 1-2 mm diam., 1.7-4.8 times shorter than lamina, canaliculate, glabrous, red; lamina 2-14 cm long, 3-17 mm wide, narrowly lanceolate, symmetric, 6.5-17.8 times longer than wide, with many spiculiform red hairs to 2.5 mm long between veins on adaxial side, base cuneate to obtuse, apex narrowly acute, margin conspicuously dentate, each tooth ending with a short soft spine, adaxially bright green to yellow-green with a distinct red-brown margin, semi-glossy, abaxially paler; midrib and primary veins barely raised adaxially, conspicuously so on abaxial side; primary lateral veins 3 to 6 pairs, evenly spaced along midrib, remotely branching along margin, the first 1-3 pairs sub-opposite; secondary venation reticulate.

Inflorescence

Axillary, dichasial at base, monochasial at apex, bisexual, protandrous, with basal male flowers and distal female flower; inflorescence axis 3-8 cm long, 1-2 mm diam.; bracts present at anthesis, eventually caducous, triangular-lanceolate, 4-5.5 mm long, 1.5-1.8 mm wide at base; bracteole absent; perianth segments pink.

Male flower. Perianth segments 4, free, pedicel 9-16 mm; outer perianth segments ovate, apex obtuse 6-7 × 4.5-5.5 mm; inner perianth segments elliptic-lanceolate 5-6 × 2.5-2.9 mm, paler than outers; stamens 12-16, yellow; androecium zygomorphic; filaments fused at the base into a column c. 0.8-1 mm long, free part c. 0.5 mm; anthers unilateral, longer than filament, oblong, c. 1.3-1.7 mm, dehiscent through lateral longitudinal slits; connective not extended.

Female flower. Perianth segments 6, free; pedicel 10-12 mm; outer perianth segments elliptic-lanceolate, apex obtuse, 7-8 × 3-4.5 mm; inner perianth segments obovate-oblanceolate, 6.5-7 × 2.5-3.5 mm, paler than outers; ovary 3-winged, unequal, with one wing conspicuously larger than the two others, 5-6 mm long vs 2-2.5 mm long, green to red-brown, composed of 3 locules; placentae septal, bi-lamellate; ovules numerous, white; styles 3, free or fused only at the base, pale yellow, persistent in fruit; stigma reniform, in a band, yellow.

Fruit

3-winged, nodding, the wings unequal; main wing c. 6-8 × 5-8 mm.

Seeds

Unknown.

REMARKS

Begonia ambodiforahensis Scherber.& Duruiss. , sp.nov. is present in cultivation in several Botanical Gardens e.g. Royal Botanic Garden Edinburgh, Botanicka Zahrada Praha and the Jardin botanique de Lyon as well as in the Collection nationale de Begonia d’Afrique et de Madagascar held by the second author. It is a very attractive species, but has proved difficult to keep on long term, requiring constant, high humidity, combined with good air movement and a very well drained mix.

Figures

FIG. 3. — Begonia ambodiforahensis Scherber. & Duruiss., sp. nov.: A, habit; B, leaf, adaxial side; C, male flower, front view; D, male flower, side view; E, androecium; F, female flower, face view; G, female flower, side view; H, gynoecium; I, styles and stigmas; J, Ovary cross-section. A, from a picture in the type locality, not collected; B-J, from a cultivated plant (no. 150333), Lyon Botanical Garden (Drawing: Vanessa Damianthe). Scale bars: A, 1cm; B, 5 mm; C, D, F, G, 2 mm; E, H-J, 1 mm.

FIG. 1. — Geographic distribution of Begonia ambanizanensis Scherber.& Duruiss.,sp.nov.,Begonia ambodiforahensis Scherber. & Duruiss.,sp.nov.and Begonia harimalalae Scherber. & Duruiss., sp. nov. in north-east Madagascar.