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| Impatiens jenjittikuliae Ruchis. & Suksathan
in Ruchisansakun & Suksathan, 2019.
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Abstract
Impatiens jenjittikuliae Ruchis. & Suksathan, a new species from a limestone area in Thasongyang District, Tak Province, Northern Thailand, is described and illustrated. This endemic new species is distinguished from the most similar, I. lacei Hook.f. through having pilose lateral sepals vs glabrous, and by the absence of long hairs along the lamina margin. Its pollen and seed morphology, stem anatomy, and pollination ecology are also observed. Furthermore, its conservation status as Critically Endangered is also assessed.
Keywords: Uniflorae, lithophytic, endemic, critically endangered
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| Figure 1. Impatiens jenjittikuliae. A Habit B Flower, front view C Inflorescence with flower in lateral view D Lateral sepals E Lower sepal F Dorsal petal G Lateral united petals. Drawn by Saroj Ruchisansakun. |
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| Figure 2. Impatiens jenjittikuliae A flower, front view B flower, lateral view C habit in situ. Photographs by Saroj Ruchisansakun. |
Impatiens jenjittikuliae Ruchis. & Suksathan, sp. nov.
Diagnosis: Impatiens jenjittikuliae is most similar to I. lacei Hook.f. It differs from I. lacei by its densely pilose lateral sepal (versus glabrous) and by having no long hairs along its lamina margin (versus distinct long hairs especially along the lower-half of leaf margin).
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Distribution: The new species is only known from the type locality in Tak Province, Thailand.
Ecology: Impatiens jenjittikuliae grows on limestone close to waterfall in a mixed deciduous forest, 520–600 m elevation (pers. obs.).
Etymology: The new species is named in honor of Dr. Thaya Jenjittikul who encouraged the first author to step in and study this lovely plant family.
Pollination ecology: The author observed five visitations by bees from the family Apidae (identified by an entomologist, Pornpimon Tangtorwongsakul) during the expeditions. The size of bee body fit well with the floral entrance (Fig. 6). Moreover, the floral structure of this new species is similar to other bee-pollinated species, e.g. I. psittacina (Ruchisansakun et al. 2016). Hence, we concluded that it is a bee-pollinated species.
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| Figure 6. Floral visitation by bee in the locality of Impatiens jenjittikuliae. |
Discussion:
Impatiens jenjittikuliae is similar to I. lacei and the other species closely related to I. pulchra Hook.f (= I. mengtszeana Hook.f. in Ruchisansakun et al. 2015) in its raceme inflorescence, shape of flower, and short fusiform capsule. The short fusiform capsule and the 4-colpate pollen grains of the new species support its placement in the subgenus Impatiens (Yu et al. 2015). In addition, I. jenjittikuliae has seeds coated with inflated cells with granulate walls similar to those described in species, such as I. napoensis Y. L. Chen, within the sect. Uniflorae (Janssens et al. 2012; Yu et al. 2015).
The cross sections of the stem of I. jenjittikuliae have shown that the new species is herbaceous, similar to the morphologically similar species in the sect. Uniflorae, I. pulchra, which also show in Lens et al. (2012) as I. mengtszeana Hook.f. (Lens et al. 2012; Ruchisansakun et al. 2015; Yu et al. 2015).
Saroj Ruchisansakun and Piyakaset Suksathan. 2019. Impatiens jenjittikuliae (Balsaminaceae), A New Species from Thailand. PhytoKeys. 124: 139-147. DOI: 10.3897/phytokeys.124.33607
