Wednesday, May 25, 2016

[Botany • 2016] The Resurrection of Boesenbergia albosanguinea (Zingiberaceae) with A New Record for Peninsular Thailand

Fig. 5. Species comparison. A. Boesenbergia prainiana (Baker) Schltr. (left), B. albosanguinea (Ridl.) Loes. (right).
B. B. prainiana inflorescence and flower. C. Boesenbergia prainiana, (left), B. albosanguinea (right). D. Pressed and dried flower of B. albosanguinea (M3291). E. Pressed and dried flower of B. prainiana (M3172). F. Pressed and dried flower of B. albosanguinea (holotype).
 (Photos: J. Mood)

 Boesenbergia albosanguinea (Ridl.) Loes. (Zingiberaceae) is resurrected from the synonymy of B. prainiana (King ex Baker) Schltr. It is redescribed in detail with comparative tables, figures, and illustrations. This species is a new record for Thailand.

Keywords. Boesenbergia prainiana, Langkawi Islands, limestone, Malaysia, Penang

Boesenbergia albosanguinea (Ridl.) Loes. in Engler & Prantl, Nat. Pflanzenfam., ed.
2, 15a: 566 (1930). – Gastrochilus albosanguinea Ridl., J. Straits Branch Roy. Asiat.
Soc. 32: 109 (1899) (“albo-sanguinea”).

Type: Specimens from a plant cultivated at Penang Botanical Gardens, Sep 1894, “Wooldridge” [but more likely Curtis] s.n. (holotype K! [K000255404]). (Fig. 1-3, 5–7; Tab. 1, 2).

Boesenbergia prainiana auct. non (Baker) Schltr.: Holttum, Gard. Bull Singapore. 13: 111 (1950). 

Distribution. Malaysia: Langkawi, Pulau Langgun; Thailand: Satun Province.

Ecology. Found on limestone outcrops in shaded habitats in close proximity to the sea.

Phenology. Observations in Satun Province and Langkawi indicate that flowering normally occurs from July to mid-October. Flowers open in the morning and close the following day.

Etymology. Named for the white and blood-red colour of the labellum.

Notes. This species as it appears in Satun Province is upright to slightly decumbent with thick, multiple stems in a clump, quite similar to the vegetative habit of Boesenbergia trangensis and B. plicata. The leaves are also plicate, but tend to be slightly smaller in size with a rounded leaf base. When fertile, it is easily identified by the very symmetrical, lanceolate inflorescence that is narrow at the base, wider in the centre and slowly tapered to the apex. The bracts are symmetrical and tightly overlap on both sides of the rachis. The leaf sheath margins and lower bracts are reddish which gives the appearance of a broad, red streak on the stem and partially up the centre of the inflorescence. The inflorescence protrudes for about half its length out of the leaf sheaths and maintains a mostly vertical stance. The flowers are pure white with a light red, narrowed, maculate pattern in the throat, and a lip lightly streaked with dark red especially on the apex margin. Ridley’s comment on the narrow opening for pollination is due to the large, overlapping lateral staminodes which cover roughly two-thirds of the labellum length, forming a tube. In the Langkawi populations, the plants tend to be generally less robust, shorter in height with narrower, shorter leaves. The leaf sheaths are red but the colour does not extend onto the rachis. The inflorescences are more cylindrical, less flattened with slightly longer, narrower bracts which sometimes deflex slightly away from the rachis on some plants. Flower shape and colour are nearly identical to the Thai populations, albeit slightly smaller.

It is concluded that Boesenbergia albosanguinea is distinct from B. prainiana. The Langkawi collections by Curtis labelled as Boesenbergia albosanguinea are confirmed, as are those from Satun Province, the latter constituting a new record for Thailand.

The disparity of Wooldridge’s type locality in the mountains of Perak as compared with the documented coastal collections in Langkawi and Satun Province cannot be explained by any known historical references such as accession books or associated Wooldridge memorabilia (pers. com. Singapore Botanic Gardens Library). The facts remain that Boesenbergia albosanguinea has never again been recorded from the Thaiping Hills and, ecologically, it is unlikely that species otherwise only known from coastal limestone sites would also be found in a distinctly different, mountainous environment. Therefore, the only logical explanation for this inconsistency is that the plant at Penang used for the holotype, protologue and illustration was not the same plant Wooldridge collected. More likely it was one of Curtis’s plants collected from Langkawi between 1890 and 1893.

J.D. Mood, A.G. Hussain and J.F. Veldkamp. 2016. The Resurrection of Boesenbergia albosanguinea (Zingiberaceae) with A New Record for Peninsular Thailand.
Gardens’ Bulletin Singapore. 68(1): 109–124.