Argyreia pseudosolanum Traiperm & Suddee, 2020

Traiperm, Paweena & Suddee, Somran, 2020, A new species of Argyreia (Convolvulaceae) from Thailand, PhytoKeys 149, pp. 109-115 : 109

Argyreia pseudosolanum Traiperm & Suddee sp. nov. Figs 1 , 2 , Table 1

Diagnosis.

Similar to Argyreia corneri in having a white rotate corolla, but differs in narrowly elliptic, oblong or lanceolate leaf shape (versus ovate), the ovate outer sepal shape (versus broadly ovate), the limb distinctly star-shaped with 5-triangular lobes (versus limb vaguely 5-angled).

Type.

Thailand, Bueng Kan Province, Bueng Khong Long District, Phu Langka National Park, 530 m elev., 12 Sep 2018, S. Suddee, P. Puudjaa, C. Hemrat & W. Kiewbang 5363 (holotype: BKF!; isotypes: BKF!, K!, QBG!).

Description.

Climbers up to 2 m tall; stems woody at base, herbaceous above, 1.5-3 mm diam. on flowering stems; covered at first with simple, non-glandular, appressed greyish trichomes, later glabrous or glabrescent, grooved lengthwise when dry. Leaves simple; petioles 0.3-1.2 cm long, grooved adaxially, densely-appressed whitish hairy or glabrescent; leaf blades narrowly elliptic, oblong or lanceolate, 7-17 × 1-5 cm, base cuneate to obtuse or rounded, margins entire, apex acute or mucronate-apiculate; papery or chartaceous, adaxially dark green, glabrous, abaxially paler, densely-appressed shining sericeous; secondary veins 5-8 on either side, veins slightly raised adaxially, more prominently raised abaxially. Inflorescences axillary cymes, 3-5-flowered; peduncle cylindrical, 4-6 mm long, densely-appressed sericeous; bracts narrowly lanceolate, 5-7 × 1.5-2 mm, adaxially glabrous, abaxially densely whitish hairy, caducous; pedicels 4-5 mm long, terete, whitish sericeous. Flowers diurnal; sepals subequal, 2 outer obovate-elliptic, 7.5-8 × 6-8 mm, abaxially whitish sericeous, adaxially glabrous, margins entire, apex rounded, third sepal asymmetrical, 2 inner sepals obovate-rounded, 5-6 × 6-7 mm, abaxially whitish sericeous, adaxially glabrous, thinner at margins. Corolla rotate, 1.8-2 cm long, pure white, tube short, limb distinctly star-shaped, ca. 3 cm in diam., 5-lobed, lobes triangular, apex emarginate; densely appressed whitish sericeous outside on mid-petaline bands and tube. Stamens exserted, subequal, 18-24 mm; filaments basally fused to corolla tube, glabrous or nearly glabrous with a few multicellular uniseriate hairs at attachment point; anthers oblong-sagittate, 3-4 mm long, longitudinally dehiscent. Pistil exserted, slightly longer than stamens, white; disc annular, undulate; style simple, filiform, glabrous, base expanded, conical; stigmas 2, subglobose with flattened base to globose. Fruit berries, globose to subglobose, enclosed in enlarged calyx, 0.8-1 cm in diam.

Phenology.

Flowering and fruiting (young fruit) in September, during the latter part of the rainy season.

Distribution and ecology.

In mixed deciduous forest on a sandstone plateau. Elevation: 530 m.

Vernacular name.

Khruea sawate phulangka (เครือเศวตภูลังกา), the name is given by the authors.

Etymology.

The specific epithet refers to the corolla shape, which is similar to Solanaceae and not found elsewhere in Argyreia .

Conservation status.

Argyreia pseudosolanum is known only from Phu Langka National Park with an estimated area of occupancy around 1 km2. The number of mature individuals in the population is less than 50. The species occurs near the large golden stupa on the top of the Phu Langka plateau which has religious activities in the dry season. This area might be disturbed by these activities and this could affect the survival chances of this species. It is assessed here as Critically Endangered, CR B2ab(iii); D, following the IUCN Criteria (2017).

Additional specimens examined.

Thailand, Bueng Kan Province, Bueng Khong Long District, Phu Langka National Park, 530 m elev., 12 Sep 2018, S. Suddee, P. Puudjaa, C. Hemrat & W. Kiewbang 5363 (BKF!, K!, QBG!); 27 Sep 2018, P. Kochaiphat 353 (BKF! 2sht., K!, QBG!).

Figures

Figure 1. Argyreia pseudosolanum. A Stem with leaves and inflorescences B adaxial leaf surface C abaxial leaf surface D upper part of leaf, showing secondary veins on adaxial leaf surface E inflorescence bracts, outer (left) to inner (right) F 5 sepals from outer (left) to innermost (right) G flower in front view H opened corolla with 5 stamens I pistil, showing undulate disc and biglobose stigma J filament insertion showing an attachment point K single stamen L close-up of lower part of stamen, showing a few multicellular uniseriate hairs M multicellular uniseriate hair N young fruits with sepals O fruit in longitudinal section, showing 2 immature seeds. All drawn by N. Chitchak from voucher specimens Suddee et al. 5363 (BKF) (A-M), P. Kochaiphat 353 (BKF) (N, O).

Figure 2. Argyreia pseudosolanum inflorescence, corolla and young fruit details. A and C inflorescence and flower in lateral view, showing cymose inflorescence with short peduncle, and rotate corolla shape B flower in frontal view, showing 5 - lobed corolla limb (star-shaped), exserted genitalia and pinkish anthers (voucher: Suddee et al. 5363) D young fruits (voucher: P. Kochaiphat 353). Photographs A-C by W. Kiewbang, D by P. Kochaiphat.