Tuesday, December 20, 2016

[Botany • 2016] Argostemma laotica • A New Species (Rubiaceae) from Laos

Argostemma laotica 
Lanorsavanh & Chantar.  


Argostemma laotica, a new species from Laos, is described and illustrated. The species appears most similar to A. concinnum but differs in having pubescent stem, corolla and ovaries, oblique leaf base, shorter pedicel and smaller anthers which a dehiscence by an apical pore. The conservation status of this new species is vulnerable (VU D2).

Keywords: Argostemma laotica, Rubiaceae, Eudicots

Argostemma laotica is similar to A. concinnum Hemsley (1895: t. 2380) in perennial herb with tuber, acute leaf apex, terminal inflorescence, 5-merous flower, triangular calyx lobes, star-shped flower and capitate stigma, but differs in having pubescent stem (vs. glabrous), leaf base oblique (vs. acute or attenuate), corolla and ovaries pubescent (vs. glabrous), and shorter pedicels of 6–7 mm long (vs. 10–20 mm long) and smaller anthers of 2.2–2.5 mm long (vs. 5–6.5 mm long), which a dehiscence by an apical pore. 

 Phenology:— Flowering in July.

 Etymology:— The specific epithet refers to the country in which the specimen was collected.

Distribution and ecology:— Endemic to Laos and only known from the type locality in Xiangkhoang, growing on wet rock, along river, elevation ca. 200 m.

  Soulivanh Lanorsavanh and Pranom Chantaranothai. 2016.  Argostemma laotica (Rubiaceae), A New Species from Laos. Phytotaxa. 270(3); 223–226. DOI:  10.11646/phytotaxa.270.3.7