Benthamia lakatoensis Descourv. & Hervouet, 2025

Hervouet, Jean-Michel, Descourvières, Pascal, Hermans, Johan & Longou, Ludivine, 2025, Revision of the genus Benthamia A. Rich. (Orchidaceae, Orchidioideae, Habenariinae), Adansonia (3) 47 (11), pp. 171-249 : 209-210

Benthamia lakatoensis Descourv. & Hervouet , sp. nov.

( Figs 54 ; 55 ; 56 ; 57 )

DIAGNOSIS. — Similar to Benthamia nivea but differing by the shape of the leaves, elliptic with apex rounded (vs elliptic with apex acute in Benthamia nivea ), and in the smaller flowers, 4-6 mm (vs 5-10 mm for Benthamia nivea ), forming a straight tube in their lower third (vs forming a curved tube), with petals not or hardly asymmetrical (vs completely asymmetrical), lateral lobes of lip divergent (vs parallel when flattened), base of lip narrow, hardly wider than the midlobe (vs base of lip twice wider than the midlobe), the dorsal sepal and petals ending in a single vertical plane in fresh specimens (vs flowers not opening widely). The auricles are nearly twice as long and the column is much less apiculate, the spur is half the length. The flowering season is August-November (vs February-April).

TYPE MATERIAL. — Madagascar • Alaotra-Mangoro, route de Lakato ; 19°11’30”S, 48°26’00”E; XI.1963; J. Bosser 18340; holotype: P [ P00094562 ] !.

ETYMOLOGY. —Referring to « Lakato », a village near Andasibe in the Alaotra-Mangoro region, where the type of the plant was first found.

PHENOLOGY. — August to November.

DISTRIBUTION AND ECOLOGY. — Madagascar. Only few plants have been recorded so far, from c. 725 to 1200 m, in medium altitude moist evergreen forest, from north to south. The type was collected along the road between the Route Nationale 2 and Lakato, a region that has suffered from severe deforestation in the recent years, it is very unlikely that it still exists there. A specimen has been located in Zahamena forest reserve, another one in Ranomafana national park, and more recently another from Tsaratanana area ( Fig. 56 ).

CONSERVATION. — Apart from the specimens found recently, this species has been collected in two localities only, one of them (road to Lakato) being heavily deforested. It can be considered Critically endangered (CR) according to criterion B2, with AOO less than 10 km ², severely fragmented and in continuing decline.

ADDITIONAL SPECIMENS EXAMINED. — Madagascar • Alaotra-Mangoro, massif de l’Andrangovalo au sud-est du lac Alaotra, réserve de Zahamena; 17°40’S, 48°45’E; alt. 1200 m; X.1937; H. Humbert et al. 17922; P [ P00094547 ] ! • Haute Matsiatra, parc national de Ranomafana, parcelle n°1, 26.VIII.1992; R. Rakoto 208; P [ P00692459 ]!, K!, MO [ MO3022622 ] ! • Alaotra-Mangoro, Lakato, Bosser 17229; Jean Bosser and Jean-Pierre Peyrot slides. It is very likely that the specimen Bosser 17229 referred to in the Bosser slide collection is in fact Bosser 18340, there is no specimen Bosser 17229 in P • Diana, Ambanja district ; alt. 725 m; 20.XI.2022, L. R. Rajaovelona RJL1662; K [ K001304657 ] !.

Notes

A photograph of this species was published by Bosser & Lecoufle (2011: 179), as Benthamia nivea . However, it differs from the type material of Benthamia nivea and appears to be the new species. The auricles are twice as long as the anther and are similar to those of Benthamia erinacea . They are thinner than those of Benthamia nivea .

See also: Bosser & Lecoufle (2011: 179, as Benthamia nivea ).

DESCRIPTION

Erect epiphytic herb, 15-25 cm tall. Tubers many, fusiform and villous, 3-6 cm long. Stem 1.5-2 mm in diameter, with the base covered by 1 sheath, with 2-3 basal leaves and sometimes another one higher up, followed by one or two sterile bracts. Leaves elliptic, 3-7 × 1-2 cm, with apex rounded, sometimes slightly mucronate. Rachis cylindrical, with 10-35 flowers, 6-10 cm long. Floral bracts narrowly lanceolate, very acuminate, longer than the ovary at the base of the rachis, then as long as the ovary. Ovary 7-10 × 1.5 mm. Flowers 4-6 mm long without the ovary, opening widely, snow white; all floral parts forming a straight tube in the lower third of the flower; dorsal sepal linear-obtuse, 4-6 × 1 mm, with a narrowed base, single-veined; lateral sepals a little wider, spreading, 4-6.5 × 1-1.1 mm; petals elliptic, with the apex rounded or subacute, 3-veined, obscurely dissymmetric, 4.5-6.5 × 1.2- 2 mm, 3-4-veined in the lower 2/3rd; dorsal sepal and petals spreading, to the point of ending in a single vertical plane; lip narrowly oblong, 4-6.5 × 2.5-3.3 mm, with narrow base, without callus, trilobed at the apex in about the third of its length, 3-5-veined, lateral lobes wide, nearly as wide as the midlobe, divergent when flattened, subacute, 1.5-2 × 1 mm, midlobe slightly longer, 2-2.5 × 1.2 mm, apex subacute but folded upward, so that it appears truncate in fresh flowers, base of lip about as wide as the midlobe; spur subglobose, saccate, very short, 0.5-1 × 0.9 mm. Column 0.6-1 × 0.5- 1 mm, anther almost orbicular, subterete, with an obtuse apiculus; auricles falciform, narrow, glandular, twice as long as the anther; rostellum tridentate.

Figures

FIG. 54. — Benthamia lakatoensisDescourv. & Hervouet,sp. nov.,Lakato road, Andasibe region, Madagascar, September 1963. Photograph by Jean Bosser.

FIG. 55. — Benthamia lakatoensisDescourv. & Hervouet,sp.nov.,Lakato road, Andasibe region, Madagascar,September 1963. Photograph by Jean Bosser.

FIG. 56. — Distribution map of Benthamia lakatoensis Descourv. & Hervouet, sp. nov.

FIG. 57. — Benthamia lakatoensis Descourv. & Hervouet, sp. nov.: drawing by Ludivine Longou, after photographs and dried specimens: A, habit; B, front view of flower; C, side view of flower. Scale bars: A, 10 mm; B, C, 1 mm.