Benthamia humbertii H.Perrier

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 : 207-208

Benthamia humbertii H.Perrier

( Figs 51 ; 52 )

Bulletin de la Société botanique de France 81: 35 ( Perrier 1934).

TYPE MATERIAL. — Madagascar • Ihorombe, pic d’Ivohibe; 22°30’25”S, 46°58’15”E; alt. 1500-2000 m; 5 - 11.XI.1924; H. Humbert 3287; lectotype: P [ P00094517 ]!, here designated; isolectotype: P [ P00094518 ]!, B [ B100365917 ]!, one of the few specimens saved from the destruction of the Berlin herbarium at the end of second World War, G!, K [ K000415555 ]!, TAN [ TAN000409 ] !.

ETYMOLOGY. — Named for Henri Humbert (1887-1967) who collected the type material.

PHENOLOGY. — October and November.

DISTRIBUTION AND ECOLOGY. — Madagascar. In the southern half of the country, in montane grasslands from 1100 to 2000 m ( Fig. 53 ). CONSERVATION. — So far only known from fewer than 10 localities only, with an AOO less than 2000 km ², and habitat threatened by frequent bushfires, it is considered Vulnerable (VU), despite a very large EOO according to criterion B2. It was considered EN by IUCN in 2015 (https://doi.org/10.2305/IUCN. UK.2015-2.RLTS. T70102654A70155404.en).

ADDITIONAL SPECIMENS EXAMINED. — Madagascar • Haute Matsiatra, Andringitra, Andrianony , cirque de Manjarivolo; alt. 1800 m; 1.XI.1970; J. L. Guillaumet 3451; TAN ! • Anosy, massif du Beampingaratra, col de Vohipaha; 24°32’S, 46°53’E; alt. 1100- 1400; 16.XI.1928; H. Humbert 6658; syntypes: P [ P00094519 , P00094520 ] ! • Atsimo-Atsinanana, bassin de l’Itomampy, mont Papanga près de Befotaka; 23°51’S, 46°57’E; alt. 1300-1700 m; 2-3. XII.1928; H. Humbert 6906 bis; syntype: P [ P00094521 ] ! • Haute Matsiatra, Andrambovato, près de Fianarantsoa; 21°31’S, 47°25’E; XI.1963; J. Bosser 18306; P [ P00692242 , P00692243 ] ! • Amoron’i Mania, Antoetra; 20°46’27”S, 47°19’16”E; photographs by Anton Sieder • Haute Matsiatra, Ankazomivady; 20°46’22”S, 47°10’48”E; 1721 m; 12.VIII.2017; photographs by Hasimbola Rakotobe • Haute Matsiatra, Ambondrombe; 21°52’30”S, 47°15’37”E; alt. 1875 m; 29.X.2022; photographs by Jean-Michel Hervouet.

NOTES

One of the largest Benthamia species in Madagascar. It closely resembles B.latisatis from the Mascarenes but is easily distinguished by the leaves (alternate amplexicaul, 6-8 cm long vs 12-30 cm long, higher on the stem), by the sepals and petals which are 1-veined (3-veined in B. latisatis ), the bigger lip with a crest, the non-apiculate anther and the indented rostellum in the middle. See also: Perrier (1939: 36), Cribb & Hermans (2009: 49), Bosser & Lecoufle (2011: 177, the photograph shows Benthamia elata ).

DESCRIPTION

Robust terrestrial herb, 50-70 cm tall.Tubers many, fusiform. Stem thick, 5-10 mm in diameter, carrying only 2-3 very lax sheaths in its lower part, of which the 2 outer ones are black, then 4-8 developed alternate amplexicaul leaves above the middle and higher again a few short sheaths becoming gradually similar to the floral bracts. Leaves rather thick, broadly oval-lanceolate, 6-8 × 2-4 cm, acuminate-acute. Rachis elongate, 15-18 cm, cylindrical, 2-2.4 cm in diameter, dense, with 35-100 flowers. Floral bracts narrowly lanceolate, concave at base, acuminate-acute, 1-veined, 10-14 × 3 mm, the lower ones a little longer than the ovary and flower, the upper ones about as long. Ovary twisted, 7-20 × 1.5-3 mm, reddish. Flowers greenish yellow, thick and short, 4-5 mm without the ovary; sepals 1-veined, dorsal sepal broadly elliptic, 4-5 × 1.7-2 mm, lateral sepals concave, elliptic to subtriangular or even navicular, very obtuse to subacute, 4.2-4.5 × 1.7-1.8 mm; petals elliptic, asymmetrical, 3.5-4 × 1.5-2 mm; lip broadly obovate, 4.5-5 × 3-4.5 mm, thick, trilobed in the apex, the lateral lobes short, triangular with obtuse apex, 0.4- 0.5 mm long, the midlobe truncate, obtuse, 1-1.5 × 1 mm, thickened; spur scrotiform, compressed, wider than long, 1-2 × 1.8-2 mm. Column 1-1.2 × 1-1.2 mm, anther obtuse, not or hardly apiculate; auricles slightly spathulate, equalling half the length of the anther or less; rostellum trilobed, with two small horizontal lateral lobes, midlobe toothed, short and thick, slightly emarginate in the middle; stigma short, forming two distinct small, rounded masses.

Figures

FIG. 51. — Benthamia humbertiiH.Perrier:Mount Ambondrombe,Madagascar, 11 April 2018. Photograph by Jean-Michel Hervouet.

FIG. 52. — Benthamia humbertii H.Perrier:Mount Ambondrombe,Madagascar, 29 October 2022. Photograph by Jean-Michel Hervouet.

FIG. 53. — Distribution map of Benthamia humbertii H.Perrier.