Goniothalamus saccopetaloides Y.H.Tan & Bin Yang, 2020

Yang, Bin, Zhu, Ren-Bin, Ding, Hong-Bo, Bouamanivong, Somsanith & Tan, Yun-Hong, 2020, A new species and two new records of Goniothalamus (Annonaceae) from Lao PDR, PhytoKeys 138, pp. 17-25 : 17

Goniothalamus saccopetaloides Y.H.Tan & Bin Yang sp. nov. Fig. 1

Diagnosis.

Goniothalamus saccopetaloides is morphologically similar to G. yunnanensis W.T. Wang with elliptic-oblong to oblong leaf blades and broadly lanceolate, pinkish orange to reddish brown outer petals, but easily distinguished by having almost fleshy, involute, saccate outer petals, subglobose and single seeded monocarps.

Type.

Lao PDR. Specific location unknown. Voucher from a cultivated plant at the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 2 May 2019, B. Yang, XTBG-0054 (holotype, HITBC!).

Description.

Shrub to small tree, to 3 m tall. Young branches glabrous. Leaf laminas 15.5-27.8 cm long, 4.5-8.2 cm wide, length/width ratio ca. 3.4, elliptic-oblong to oblong, apex acuminate, base cuneate to attenuate, papyraceous, glabrous abaxially and adaxially; midrib glabrous and (strong) prominent abaxially, glabrous and impressed adaxially; secondary veins 13-18 pairs, (slightly) impressed adaxially; tertiary veins percurrent, distinct; petioles 5-12 mm long, 2-3 mm in diameter, glabrous. Flowers 1-7, often on the main trunk (cauliflory) and on older branches (ramiflory), pendents; flowering pedicels 2-5 mm long, sparsely hairy; pedicel bracts 3-6, 1-2 mm long. Sepals 5-6 mm long, 5-7 mm wide, basally connate, apex acuminate, broad ovate, puberulous abaxially, glabrous adaxially, greenish-yellow, venation longitudinal slightly conspicuous adaxially, indistinct abaxially. Outer petals 1.4-2.7 cm long, 0.7-1.2 mm wide, length/width ratio 1.6-3.0, almost fleshy, involute, saccate, elliptic lanceolate to broadly lanceolate, sparsely puberulous abaxially, subglabrous adaxially, yellowish green in young stage, pinkish orange to reddish brown in mature stage, venation slightly distinct adaxially, occasionally slightly distinct abaxially. Inner petals 6.5-12 mm long, 5-10 mm wide, length/width ratio 1.1-2.2, broadly ovate to obovate, sparsely puberulous abaxially, pubescent adaxially, yellowish green in young stage, pinkish orange to reddish brown in mature stage, base attenuate to a 2-3 mm claw. Stamens ca. 80 per flower, 1.2-1.5 mm long, 0.6-0.7 mm wide; connectives truncate. Carpels 18-22 per flower, ovary 1.5-2 mm long, light green, with white hairs; stigma and style 2-3 mm long, glabrous. Immature fruits green, with small white dots, mature fruits orange to red; fruiting pedicels 3-5 mm long, 1.5-2 mm in diameter, subglabrous. Monocarps one seeded, 12-13 mm long, 9-11 mm wide, length/width ratio 1.2-1.3, subglobose to ellipsoid, base and apex rounded, smooth, subglabrous, glossy, pericarp medium-thick, ca. 1.5 mm thick, stipes subsessile to 1.5 mm long, ca. 2 mm in diameter, glabrous. Seeds 9-10 mm long, ca. 7 mm wide, length/width ratio 1.3-1.4, ellipsoids, testa slightly rugose, dark brown to black brown, aril orange.

Etymology.

The new species is named after its saccate and almost fleshy outer petals.

Phenology.

Goniothalamus saccopetaloides has been observed in flowers from the end of March to May and in fruits from July to September.

Distribution and habitat.

G. saccopetaloides was originally distributed in Laos; the exact location and its wild habitat remains unknown. Additional collections in the future may help to clarify its full distribution.

Conservation status.

Due to insufficient field surveys so far, very limited details about its natural distribution and population status are currently known. Further investigation is required to determine more distribution sites and conservation status of the new species; at this moment we consider it as data deficient (DD) according to the IUCN Red List Categories ( IUCN 2012).

Additional specimen examined

(paratype). Lao PDR. Specific location unknown. Voucher from the cultivated plants at the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 2 May 2019, B. Yang, XTBG-0055 (HITBC!).

Notes.

Goniothalamus saccopetaloides is morphologically similar to G. yunnanensis ; however, in addition to the description in the diagnosis, the two species can be easily distinguished by other characters. Goniothalamus saccopetaloides has 1 to 7 flowers, often on the main trunk (cauliflory) and on older branches (ramiflory), scarcely on young growth, whereas G. yunnanensis has 1 to 2 flowers, axillary, often on young growth, sometimes from leafless nodes ( Li et al. 2011). Moreover, G. saccopetaloides has one ovule per carpel, subglobose monocarps and seeds with rounded apices, and G. yunnanensis has 2 ovules per carpel, ellipsoid monocarps and seeds with acute apices ( Li et al. 2011).

Figures

Figure 1. Goniothalamus saccopetaloides Y. H. Tan & Bin Yang, sp. nov. A habit B leafy branch C flowers on main trunk D fruits on main trunk E leaves (adaxial and abaxial surface) F flowers G-H dissected flowers I carpels J longitudinally dissected monocarp K seeds. Photographed by R. B. Zhu and B. Yang.