Thursday, December 17, 2020

[Botany • 2020] Gastrodia agnicellus (Orchidaceae) • A New Holomycotrophic Orchid from southeast Madagascar

Gastrodia agnicellus Hermans & P.J.Cribb

in Hermans, 2020.

The new orchid, Gastrodia agnicellus from Madagascar is described for the first time and compared with similar species from the region. Its unusual holomycotrophic habit and flowering beneath leaf humus are discussed; a full description and detailed illustration are provided.

Gastrodia agnicellus Hermans & P.J.Cribb.
a, l/s flower; b, habit and flower, face view; c, fruit and t/s fruit; d, column; e, corolla opened and lip; f, fruit, short stem and long stem; g, lip & lip side view; h, column, and column side view; i, anther cap; j, seed, side view and face view.
Drawn by Deborah Lambkin from herbarium specimens and field photographs.
 Scale bars with measurements given.

The flower of Gastrodia agnicellus Hermans & P.J.Cribb, showing the stem and part of the rhizome. Ranomafana September 2019.
Photograph: Rick Burian.

Gastrodia agnicellus Hermans & P.J.Cribb, sp. nov. 

Type: Madagascar, Fianarantsoa Prov., near Ifanadiana, c. 800 m, ex Malala, 1999, Hermans 2355 (holotype, K). Fianarantsoa Prov., Ranomafana, Sept. 2019, Field Observations, Hermans et al. (photographs K).
Distribution: Endemic to SE Madagascar.

Habitat: Humid evergreen forest, in deep shade underneath leaf litter and humus; 600–850 m.

Etymology: The species name refers to the woolly covering on the rhizome, the ear‐like petals and also alludes to the name of the botanical artist who brought the new species to life in her drawing.

Conservation: The new species has only been recorded from the Vatovavy‐Fitovinany region, Fianarantsoa province. One of the sites is within the Ranomafana Protected Area, the extent of occurrence is estimated to be very small and in continuing decline due to habitat destruction caused by fire and agriculture. In addition, Gastrodia require specific mycorrhizal associations for carbon uptake throughout their life cycle (Martos et al., 2009, 2015a, 2015b). These combined factors are likely to mean that the new species is Endangered.


Johan Hermans. 2020. GASTRODIA AGNICELLUS: A New Holomycotrophic Orchid (Orchidaceae) from southeast Madagascar. Curtis's Botanical Magazine. DOI: 10.1111/curt.12354