Phyllagathis guidongensis K. M. Liu & J. Tian, 2016

Tian, Jing, Pen, Ling, Zhou, Jian-Cheng, Tian, Xue-Hui, Yi, Ren-Yuan, Liu, Lei, Cai, Xiu-Zhen, Kuang, Ren-Ping & Liu, Ke-Ming, 2016, Phyllagathis guidongensis (Melastomataceae), a new species from Hunan, China, Phytotaxa 263 (1), pp. 58-62 : 58-61

Phyllagathis guidongensis K. M. Liu & J. Tian , sp. nov. (See Figs. 1 and 2 )

Diagnosis: —This new species is similar to P. stenophylla , but it differs from the latter by its creeping stolons 10–30 cm long; prostrate lower part of the stems narrowly elliptic leaf blades 1.8–3.0 × 0.5–1.0 cm, apex obtuse or shortly acuminate, with both sides sparsely covered with bristles and villose, adaxial surface densely covered with yellow glandular dots, solitary flowers, capsules not obviously angulate.

Type: — CHINA. Hunan Province: Guidong County, Pule Town , 25°53′N, 113°58′E, elevation ca. 970 m. 3 July, 2013, K. M. Liu, R. Y. Yi & L. Peng 24147 (holotype, HNNU!; isotype, HNNU, CSFI!) ,

Paratypes: — CHINA. Hunan Province: Guidong County, Dongluo Town, elevation ca. 624 m. 6 September, 2014, X. L. Yu & M. Li 14090807 ( CSFI!).

Subshrubs, 10–30 cm high, multi-branched, lower part of stems recumbent, creeping stolon with adventitious roots, young branches cylindrical and green, perennial branches brown and glabrous. Leaves opposite, blade narrowly elliptic, 1.8–3(–4) × 0.5–1.2 cm, apex obtuse or shortly acuminate, base cuneate, margin inconspicuously toothed and with long bristles; adaxial surface covered with sparse bristles or villose, much denser along the veins; abaxial surface covered with sparse bristles and yellow glandular dots; secondary veins 1 on each side of the midvien, adaxially inconspicuous, abaxially prominent; petiole 3–10 mm long, densely pubescent. Flower solitary and terminal, pedicels 6–10 mm long and pubescent; hypanthium 5 mm long, cup-shaped pubescent; calyx lobes 4, linear, 7–10 × 1 mm, apex acuminate; petals 4, pink, ovate, ca. 1.2 × 0.8 cm apex acuminate; stamens 8, equal in length, filaments ca. 1 cm long, anthers lanceolate, ca. 7 mm long, the base slightly tuberculate; pistil formed from 4 fused carpels, ovary ovoid, placentation axiallary, 4-locular, ovule many, ovary apex with a 4-part membranous crown and lobes with small dentations, style ca. 1.6 cm long. Capsule cup-shaped, ca. 6 × 5 mm, not angulate, peduncle 1.2–2.0 cm long. Seeds ca. 0.9 × 0.1 mm and cuneate, many with conical air sacs on the back.

Palynology: —Single grain pollen ( Figure 3 : a), with 3 channels; equatorial view ellipsoid ( Figure 3 : b); 3-lobed oblate in polar view ( Figure 3 : c), pollen grain 13.8 × 11.5 μm ( P), 12.6 × 12.0 μm ( E), pollen ditch long, fusiform, ditch area wiht a fold; the outer wall surface with nodular swellings ( Figure 3 : d).

Seeds micro-morphology: —Seeds cuneate, brown, with a dorsal conical air sac ( Figure 3 : e–g). It seems that seeds with inflated appendages may be the result of a competition during development between the cells of the seeds and the cells of the carpel. This agrees with the habitat of these plants that grow on the margins of strams. The surface of the testa consists of epidermal cells with a lobulate margin resembling a jigsaw puzzle ( Figure 3 : h).

Phenology: —Flowering from July to November and fruiting from August to December.

Etymology: —The specific epithet derives from the type locality, Guidong County, Hunan Province, China.

Distribution and ecology: —The new species is known from Pule and Dongluo towns in Guidong County, Hunan Province, China. It grows in rock crevices along streams, at 600–1000 m elevation.

Relationships: —This new species is similar to P. stenophylla , but it differs from the latter by its creeping stolons 10–30 cm long; prostrate lower part of the stems narrowly elliptic leaf blades 1.8–3.0 × 0.5–1.0 cm, apex obtuse or shortly acuminate, with both sides sparsely covered with bristles and villose, adaxial surface densely covered with yellow glandular dots, solitary flowers, capsules not obviously angulate. More differences between P. guidongensis and P. stenophylla are summarized in Table 1.

Figures

FIGURE 1. Phyllagathis guidongensis: (A) habit with flowers; (B) stamen (profile view); (C) longitudinal profile of flower; (D) petal; (E) leaf adaxial view (lower half) and abaxial surface (upper half); (F) seed. (Drawn by Jing Tian)

FIGURE 2. Phyllagathis guidongensis: (a), (b) and (c) habitat; (d) mature plant in the wild; (e) flower bud; (f) fruit; (g) flowering plant; (h) and (i) dissection of floral parts; (j) longitudinal section (right) and cross section of fruits.

FIGURE 3. Scanning electron microscope (SEM) photos of pollen and seeds for Phyllagathis guidongensis:(a)–(h): (a), (b) and (c) pollen; (d) ornamentation of pollen surface; (e), (f) and (g) seed; (h) sculpturing of seed surface.