THAI FOR. BULL. (BOT.) 36: 61–69. 2008.
Scaphium affine (Mast.) Pierre (Sterculiaceae) new for Thailand
PHONGSAK PHONSENA* & PETER WILKIE**
ABSTRACT. A third species of Scaphium in Thailand, Scaphium affine (Mast.) Pierre, discovered in E, SE & PEN Thailand, is described and illustrated.
The genus Scaphium (Sterculiaceae) consists of 8 species distributed in SE Asia from Burma, through Thailand, Cambodia, Malaysia, Singapore, Sumatra, and Bangka to Borneo. For the Flora of Thailand the family Sterculiaceae was recently published (Phengklai, 2001) where Scaphium is represented by 2 species: S. linearicarpum (Mast.) Pierre, with a cordate leaf base, and S. scaphigerum (Wall. ex G.Don) G.Planch., with the leaf base mostly obtuse, never cordate.
During fieldwork in SE Thailand specimens belonging to this genus were collected and all determined by Phengklai (l.c.) to S. scaphigerum, which clearly represented two distinct species, Scaphium affine (Mast.) Pierre and S. scaphigerum. These two species are distinct in a number of characters including the morphology of the seeds as described by Pierre (1889) and morphology of seedling development observed from seeds grown in the nursery of the Khao Hin Son Botanic Garden, SE Thailand (Table 1).
According to the revision of the genus by Kostermans (1953), S. affine was considered a synonym of S. macropodum (Miq.) Beume´e ex K.Heyne overlooking the salient differentiating characters of the embryo, clearly depicted by Pierre (l.c., fig. 200). S. macropodum characterized by more tubular flowers is clearly differentiated from S. affine and S. scaphigerum, both possessing shorter, campanulate perianth. The differences between S. scaphigerum and S. affine are summarized in Table 1, and the differences in the seedlings, especially in the cotyledons is shown in figure 3.
For standardization with the Flora account Scaphium is recognized here as belonging to the Sterculiaceae. However, it should be noted that phylogenetic studies have suggested that it be placed in the subfamily Sterculioideae of an expanded Malvaceae (Alverson et al., 1999; Bayer et al., 1999, Wilkie et al., 2006).
The Forest Herbarium, National Park, Wildlife and Plant Conservation Department, Chatuchak, Bangkok, 10900, Thailand; e-mail: firstname.lastname@example.org.
* Royal Botanic Garden Edinburgh, Inverleith Row, Edinburgh, EH3 5LR, Scotland, UK: e-mail: