Benthamia calceolata 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 : 188-189

Benthamia calceolata H.Perrier

( Figs 20 ; 21 ; 22 )

Bulletin de la Société botanique de France 81 ( Perrier 1934: 32).

TYPE MATERIAL. — Madagascar • Sava, Andratamarina, near Mananara ; 16°17’49”S, 49°43’37”E; 20.VIII.1920; R. Decary 24; lectotype: P [ P00094475 ]!, here designated; isolectotype: P [ P00094476 ]!, only a flower dissection of the former .

ETYMOLOGY. — From Latin “ calceolatus ”: slipper-shaped, referring to the shape of the lip.

PHENOLOGY. — From June to November.

DISTRIBUTION AND ECOLOGY. — Madagascar. Only known from four locations, all near the east coast, almost from north to south. In humid places, in riparian Pandanus forest or lowland moist evergreen forest. Altitude from 100 to 500 m ( Fig. 23 ).

CONSERVATION. — Known so far from only four localities but the very large EOO suggests that it has been largely overlooked due to its diminutive habit. IUCN quoted it EN in 2015, under criteria B2ab(ii,iii,iv,v) (https://doi.org/10.2305/IUCN. UK.2017-2.RLTS. T70102664A70132920.en). The only recent observation has been in the Ambodiriana forest, which has an area of 240 ha. As fewer than 50 individuals have been counted, considering only the recently observed living specimens would indicate a Critically endangered species (CR) status under criterion D.

ADDITIONAL SPECIMENS EXAMINED. — Madagascar • Sava, Manantenina ; 24°16’49”S, 47°19’10”E; 10.VI.1925; R. Decary 3877; P [ P00094477 ] ! • Sava, Masoala Peninsula , west of village of Andrembona ; 15°17’25”S, 50°13’10”E; alt. 470 m; 19.XI.1993, K. Lance 39; K!.

NOTES

This species differs from all the others in the genus by the pouched lip. It has recently been seen in October 2022 in the Ambodiriana forest on the east coast of Madagascar, by Véronique Lavergne, who provided us with the first photographs of the species. The fasciculate habit observed on the type was not confirmed in recent observations.

There are two sheets of the R. Decary 24 gathering, we chose P00094475 as the lectotype, the isolectotype P00094476 being a dissected flower.

See also: Perrier (1939: 28), Cribb & Hermans (2009: 43).

DESCRIPTION

Erect terrestrial herb, 30-60 cm tall.Tubers 5-8, elongated, up to 3 cm, cylindrical or fusiform, ending in a root. Stem erect, 2-3 mm in diameter, with a basal leaf and then 6-8 scale-like leaves, slowly turning into very acute floral bracts with linear blade. Leaf 1, oblong-lanceolate, c. 14 × 3.2 cm, acutely narrowed at both ends. Rachis slender, lax, narrow, 17 × 1 cm, bearing 30-45 flowers. Floral bracts lanceolate, very acute, in the middle of the rachis slightly longer than half the length of the ovary. Ovary 4.5-6 × 1.3 mm. Flowers 3 mm without the ovary, greenish yellow; all sepals 1-veined and with an obscure dorsal keel; dorsal sepal oval, obtuse or with apex subacute, 1.5-2.2 × 0.8-1 mm; lateral sepals oval-obtuse, 1.5-2.2 × 0.8- 1 mm; petals much thicker, very concave, obovate, 1.4-2 × 0.7-0.8 mm, a little cucullate and very rounded at the tip; lip entire or very obscurely trilobed at apex, 1.8 × 1-1.1 mm, slipper shaped and very short, a little verrucose on the outside, with apex truncated; spur scrotiform, bilobed, as wide at the tip as long, 1-1.1 × 0.8-1 mm, contracted at the base, with a clear deep furrow at the tip. Column sub-terete, very different from others in the genus, 0.7-1 × 0.5-1 mm, with apex digitate, 0.3 mm long, slightly canaliculate in its internal part, overhanging the rostellum; rostellum trilobed with an erect midlobe around 0.3 mm long and two short lateral lobes; auricles basal, strap-like, nearly reaching the anther margins.

Figures

FIG. 20. — Benthamia calceolata H.Perrier: Ambodiriana forest, Manompana, Madagascar, 18 October 2022. Photograph by Véronique Lavergne.

FIG. 21. — Benthamia calceolata H.Perrier: Ambodiriana forest, Manompana, Madagascar, 18 October 2022. Photograph by Véronique Lavergne.

FIG. 22. — Benthamia calceolata H.Perrier: Ambodiriana forest, Manompana, Madagascar, 18 October 2022. Photograph by Véronique Lavergne.

FIG. 23. — Distribution map of Benthamia calceolata H.Perrier.