Bulbophyllum rheophyton J.J.Verm. & Tsukaya 2011 SECTION Beccariana Pfitz. 1889

TYPE Drawing by J J Vermeulen

Common Name The Rheophytic Bulbophyllum [refers to its being inundated at some point in its environment]

Flower Size .24" [6 mm]

Found in Kalimantan Borneo on riverbeds at lower elevations as a small sized, hot growing terrestrial with a rhizome with barely persistent bracts giving rise to distant, .48 to .72" [1.2 to 1.8 cm] between each, thinly cylindrical, somewhat flattened pseudobulb carrying a single, apical, elliptic to elliptic-ovate, acuminate, petiolate base leaf that blooms in the winter on an patent, peduncle to 3.2 to 3.6" [8 to 9 cm] long, provided with 5 bracts, rachis slightly arching to nodding, .56 to .72" [1.4 to 1.8 cm] long, densely, simultaneously, 15 to 20 flowered inflorescence with ovate, shorter than the ovary floral bracts

" Bulbophyllum mahakamense J.J.Sm., from Peninsular Malaysia, Sumatra and Borneo (see Seidenfaden and Wood 1992, p 487 for further information, under the synonymous name B. foetidolens Carr) is morphologically most similar to our rheophyte. We assume it is a sister species. B. mahakamense follows the environmental preferences of the section but has never been observed in a river bed so close to the water. Vegetatively, it is sturdier than our assumed rheophyte, but only statistically so, e.g., the leaf index (length/width) is 2.6 to 13 (B mahakamense) versus 10 to 15.9. The best diagnostic difference between the two is found in the petals: apex subacute to acuminate, and index length/width 2.3 to 4.2 (B mahakamense, 11 specimens measured), versus apex rounded, index ca. 1.6. The latter observation leads to the conclusion that our assumed rheophyte is indeed a separate species, rather than a rheophytic form of B. mahakamense." Jaap J. Vermeulen & Hirokazu Tsukaya 2011

Synonyms

References W3 Tropicos, Kew Monocot list , IPNI ; * Pl. Syst. Evol. 293: 73 Jaap J. Vermeulen & Hirokazu Tsukaya 2011; An assumed rheophytic orchid: Bulbophyllum rheophyton n.sp., from Borneo; Bulbophyllum of Borneo J J Verm & O'Byrne & Lamb 2008 drawing fide

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