Identification, sexual dimorphism and aspects of the natural history of Sapria himalayana (Rafflesiaceae) on Vietnam’s Lang Biang Plateau

Abstract

BackgroundSapria is a distinctive and narrowly host-specific holoparasitic genus belonging to the Rafflesiaceae. Sapria himalayana, rare throughout its range from NE India, SW China, Thailand to Vietnam, is a little-understood species first recorded for Vietnam in 1959, and only recollected there over half a century later in February 2017. This has facilitated an assessment of its taxonomic identity and our understanding of its morphology and natural history aspects.ResultsSix populations of Sapria at Vietnam’s Tuyền Lâm Lake, and another two populations at the Nam Ban Protection Forest and the Cam Ly area were found, in an area of about 20 km in radius. Previously documented size attributes, morphological details and colour patterns allowed clear identification of the Vietnamese taxon as Sapria himalayana f. albovinosa. A full description of the species for Vietnam is provided. Past authors have distinguished the sexes by column form and structure, colour of the upper disk, details of the inner surface of the perigone tube, and presence of ovarial chambers below the column in the female. We present additional observations that male flowers consistently have more steeply held perigone lobes than females, in which the lobes were more spread out at wider angles in fully open flowers, and that males have a much lower cupule than females. The latter difference, especially, appears to be useful for quick determination of the sex even in the advanced floral bud stage. The host plant was the lianescent Tetrastigma laoticum (Vitaceae), but superficially it was not possible to ascertain the clonal relationship of neighbouring host lianas. Male and female flowers were found mixed together in the same cluster from one individual liana. Potential pollinators included Calliphorid and Stratiomyid flies observed visiting open flowers.ConclusionsOur observations have added to an increased understanding of the morphology of this highly specialized parasitic life form. More than this, we have ascertained its occurrence in Vietnam, with information made available to authorities of the Lâm Đồng Province where our studies were conducted, for the sites to be specially demarcated for conservation and carefully managed tourism use.

DISCOVERY, DISTRIBUTION AND CONSERVATION OF THE RARE PARASITIC PLANT SAPRIA HIMALAYANA (RAFFLESIACEAE) IN BHUTAN

“…Trần et al . (2018) identified the host exclusively as Tetrastigma laoticum Gagnep. in Vietnam; this is now treated as a synonym of T. planicaule (Hook.f.)…”

“…Elsewhere, in Indo-China it now has a wider range, following its first discovery in Thailand in 1904 (Hansen, 1972;Elliott, 1992). In Vietnam it was first discovered in 1959 and its wider occurrence there has been reported in detail by Tr ần et al (2018) under the name S. himalayana forma albovinosa Bänziger & Hansen. In Myanmar (Burma) it has been reported both as forma albovinosa (Tanaka et al, 2019) and simply as S. himalayana by Akiyama (2019); the two forms of this species supposedly differ primarily in the colour of the blotches on the perianth lobes but their distinctness should be studied further as the photographs of living plants from Myanmar and Vietnam look very similar to those from Bhutan and Arunachal Pradesh which have white blotches on the perianth lobes (Hohl & Sebastian, 2014;Borah & Ghosh, 2018;Ahmad et al, 2020).…”

“…The flowers resemble and smell of decaying animal flesh and thus attract carrion flies which it is thought to facilitate pollination. Detailed accounts of floral morphology and biology in Sapria are given by Elliott (1992), Tanaka et al (2019), Nikolov &Davis (2017) andTr ần et al (2018). In Thailand it has been given the vernacular name of 'Hermit's Spittoon' (Bänziger et al, 2000).…”

Preliminary Histoanatomical Study of Sapria Himalayana Griff. F. Albovinosa Flower Buds and Its Intersection With Its Host Plant Tetrastigma Laoticum Gagnep.

“…f. albovinosa (Figure 1). The specimen was taken in March 2019 at Lang Biang Plateau, Vietnam, specifically at Tuyền Lâm Lake, Cam Ly and Nam Ban Protection Forest (similar to the sampling area of the previous study, TRẦN & al. 2018).…”

“…In early development of the late flower bud (Figure 3A), the central chamber already possesses the streaks that is closely resembles the mature flower [TRẦN & al. 2018], while the perigone-bract primordial remains undifferentiated.…”