Chlorohiptage vietnamensis T.V.Do, T.A.Le & R.F.Almeida, 2024

Van Do, Truong, Lu, Ngan Thi, Le, Anh Tuan, Lam, Mai Xuan Thi, Trinh, Xuan Thi, Deguine, Jean-Philippe, Hoang, Thao Thi & de Almeida, Rafael Felipe, 2024, Chlorohiptage (Tetrapteroids, Malpighiaceae), a distinct new genus endemic to Vietnam based on morphological and molecular data, Plant Ecology and Evolution 157 (2), pp. 125-136 : 125

Chlorohiptage vietnamensis T.V.Do, T.A.Le & R.F.Almeida sp. nov.

Figs 2 , 3 , 4

Type.

VIETNAM - Quang Tri province • Cam Lo district, Cam Tuyen commune, Rockpile summit; 16°46 ’50.9” N, 106°51 ’07.2” E; elev. 250 m; 16 Sep. 2023; fl., fr.; Do Van Truong and Le Tuan Anh ĐVT 1010; holotype: VNMN; isotypes: VNMN, SGN .

Description.

Woody climbing shrubs; young branches sericeous, older ones glabrescent, lenticels rounded, dot-like rough warts; internodes 2-2.5 cm long; axillary buds densely sericeous. Leaves simple, opposite; stipules absent; petiole 5-8 mm long, rounded, sericeous to glabrous, eglandular; leaf blades 4-7.5 × 2.5-4.5 cm, coriaceous, ovate to elliptic-lanceolate, base cuneate to attenuate, margin entire, apex obtuse to acute, sometime retuse; venation reticulate, lateral veins pinnate, 4-6 pairs, prominent on both surfaces; young leaves whitish sericeous on both surfaces; mature leaves glabrous on both surfaces, except for the midvein abaxially with sparsely sericeous; (0-)2-4-glandular abaxially along midvein near the base. Thyrses, axillary or terminal, solitary, 8-18-flowered; bracts 1.2-1.5 mm long, triangular, deciduous; peduncle 6-11 cm long, sparsely sericeous; bracteoles 4-5 × 1-2 mm, lanceolate, caducous. Flowers with pedicels 1.3-2 cm long, sparsely sericeous; sepals 5, 2.5-3 × 1.5-2 mm, ovate to elliptic, apex obtuse, adaxially sparsely sericeous, abaxially glabrous, margin entire, eglandular; petals 5, pale green to yellowish-green, patent to deflexed at anthesis, 4-5 × 3-3.5 mm, obovate to elliptic, falcate, apex acute, margin erose and velutine, base rounded to subcordate, abaxially sparsely whitish sericeous, adaxially glabrous to sparsely whitish sericeous at base; claws 1-1.5 mm long, plane; stamens 10, slightly connate at base; 9 stamens with longer and slender filaments, 3.5-4 mm long, equal, white, curved at apex, anthers 0.9-1.0 × 0.5-0.6 mm, oblong; 1 stamen with a shorter and stouter filament, 1.5-2 mm long, white, anther elliptic, 1.1-1.2 × 0.6-0.7 mm; connectives conspicuous, whitish; pollen sacs yellow, rimose; ovary 1.2-1.5 mm diam., ovoid, sparsely tomentose; styles 3, 1.0-1.2 mm long, shorter than filaments, pale green, slightly curved upwards, glabrous; stigma terminal, capitate. Mericarps 3, green turning to brown when older, with parallel veins, glabrous; dorsal wing absent; lateral wing 1, 3-lobed, 2.3-3.5 × 1.3-2.0 cm, each lobe triangular to lanceolate, apex acute to rounded. Seeds 6-7 × 4-5 mm, yellowish-white, angular-globose, glabrous. Embryo not seen.

Distribution.

Chlorohiptage vietnamensis is currently known only from the limestone areas in the Cam Tuyen commune, Cam Lo district, Quang Tri province, Central Vietnam, where the Truong Son Mountain range is located (Fig. 3 ).

Habitat and ecology.

The new species grows in open forests and on the peak of the limestone mountain in subtropical broad-leaved evergreen forests, at elevations of ca 100-250 m, with some dominant species such as Pistacia weinmanniifolia J.Poiss. ex Franch., Tetrastigma quadridens Planch., Pterospermum truncatolobatum Gagnep., Bauhinia curtisii Prain, Jasminum subtriplinerve Blume (Fig. 3 ).

Phenology.

Flowering was observed from August to September and fruiting from September to October.

Etymology.

The specific epithet is derived from the name of its country of origin, Vietnam.

Preliminary IUCN conservation assessment.

Chlorohiptage vietnamensis shows an extent of occupancy of 4 km2, represented by two populations in the small limestone areas in Cam Tuyen commune, Cam Lo district, Quang Tri province, Central Vietnam. The forests are only protected by local communities but out of the nationally protected forest areas such as National Parks and Nature Reserves. These limestone areas have continuously declined due to over-exploitation by the stone and lime factories, threatening C. vietnamensis natural habitat. Therefore, we consider this new species to face a very high risk of extinction in the wild and preliminary propose it as Critically Endangered: CR B1ab(ii,iii)+2ab(ii,iii), according to the IUCN Red List Categories and Criteria ( IUCN 2012, 2022).

Additional specimens examined.

VIETNAM - Quang Tri Province • Cam Lo District, Cam Tuyen Commune, Razorback Hill ; 16°47 ’13.3” N, 106°50 ’32.7” E; elev. 150 m; 25 Jun. 2023; Do Van Truong and Le Tuan Anh ĐVT 1008; VNMN .

Notes.

Chlorohiptage vietnamensis is easily distinguished from all species of Hiptage by the green petals (vs white to yellow), with margins erose and velutine (vs fimbriate to dentate and glabrous), androecium comprising 9 long + 1 shorter stamen (vs 9 short + 1 longer stamen), 3 styles shorter than the androecium (vs 1 style longer than the androecium), and mericarps with 1 free, 3-lobed lateral wing (vs 3 free lateral wings). For a comparison between Chlorohiptage , Hiptage , and Aspidopterys , see Table 1 .

Figures

Figure 2. Comparison of morphological traits of Chlorohiptage T. V. Do, T. A. Le & R. F. Almeida, gen. nov. with Hiptage and Aspidopterys. A - D. Chlorohiptage. A. Leaves with two basal glands. B. Close up of a thyrse. C. A flower without petals showing the androecium and gynoecium structure and eglandular calyx. D. Close up of a mericarp. E - H. Hiptage benghalensis (L.) Kurz. E. Leaves with two basal glands and marginal glands. F. Close up of a thyrse showing glandular calyces. G. Flower showing the androecium and gynoecium structure and petal with fimbriate margins. H. Close up of mericarp. I - K Aspidopterys tomentosa (Blume) A. Juss. I. Leaves eglandular. J. Floral bud showing eglandular calyx. K. Flower showing the androecium and gynoecium structure and petals with margin entire. L. Shape of mericarp. Photographed and designed by Truong Van Do, Anh Tuan Le, and Rafael Felipe de Almeida.

Figure 3. Photos of Chlorohiptage vietnamensis T. V. Do, T. A. Le & R. F. Almeida, sp. nov. from the original population in the natural habitat. A. Habitat. B. Habit. C. Branch bearing thyrses. D. Close up of a thyrse. E. Branch bearing mature mericarps. Photographed and designed by Truong Van Do and Anh Tuan Le.

Figure 4. Photographic plate of Chlorohiptage vietnamensis T. V. Do, T. A. Le & R. F. Almeida, sp. nov. A. Leaves with two basal glands (indicated by red arrows). B. Close up of a thyrse. C. Open flower. D. Shape of petals. E. Flower without petals showing the androecium and gynoecium structure and the eglandular calyx. F. Close up of a 3 - styled gynoecium. G - I. Close up of the androecium structure. J. Immature mericarp. K. Shape of the mature mericarp. Photographed and designed by Truong Van Do, Anh Tuan Le, and Rafael Felipe de Almeida (scale bars 1 mm).