Primulina cordistigma F.Wen, B.D.Lai & B.M.Wang, 2016

Lai, Bi-Dan, Wang, Bing-Mou & Wen, Fang, 2016, Primulina cordistigma, a new species of Gesneriaceae from Guangdong, China and supplementary and emendated description of floral morphology of P. yangchunensis, Phytotaxa 244 (3), pp. 283-288 : 283-287

Primulina cordistigma F.Wen, B.D.Lai & B.M.Wang sp. nov. ( Figs. 1 & 2 )

Diagnosis:—Similar to P. yangchunensis , but differs from latter by having broadly ovate to cordate leaf blades 4–5 × 2–3.5 cm (vs. narrowly ovate to narrowly elliptic leaf blades 3–7 × 1.5–3 cm), per cyme having 1–5 flowers (vs. 5–15 flowers), lanceolate bracts 3–4 × 0.5–1 mm (vs. baroadly lanceolate 0.8–2 × 0.2–0.5 mm), corolla tube 0.9–1 cm long (vs. ca. 1.5 cm long), staminodes 3 (vs. 2), cordate stigma with elliptic lobes covered by shortly puberulent hairs (vs. oblong to triangle with triangle lobes but glabrous).

Type:— China. Guangdong: Yangchun City, Helang Town, Yuxisandong, in crevice on vertical rock face of limestone caves, 08 October 2012, B. M.Wang 121008-1 (holotype IBK!, isotypes IBK!).

Additional specimens examined:— CHINA. Guangdong Province, Yangchun City, Helang Town , 11 August 2013, B. M.Wang 130811-1 ( IBK) ; the same locality, 13 October 2014, B. M.Wang 141013-1 ( IBK) .

Perennial herbs, rhizomes stocky, subterete, 1–1.5 cm long, 0.5–0.8 cm in diameter. Leaves all basal, thickly chartaceous to slightly fleshly; leaf blades broadly ovate, 4–5 × 2–3.5 cm, adaxial surface appressed pubescent and sparsely multicellular papillose-hispid, abaxial surface appressed pubescent, apex obtuse, base broadly cuneate to cordate, margin entire to rarely undulate with densely villous hairs; lateral veins ca. 5 pairs; petiole 1.5–2.5 × 0.3–0.4 cm, densely villous. Cymes 2–5, unbranched or with 1–2 branches, 1–5-flowered; peduncle 3–5 cm long, pubescent; bracts 2, opposite, lanceolate, 3–4 × 0.5–1.0 mm, densely pubescent, apex acuminate, margin entire, outside pubescent, inside glabrous. Pedicels 1.2–1.4 cm long, densely pubescent. Calyx 5-parted nearly to the base, segments lanceolate, 2.5–4 × ca. 1 mm, outside puberulent, inside glabrous. Corolla 1.8–2 cm long, outside with puberulent hairs and glandular-puberulent hairs, lobes pink to pinkish purple, tube funnel-form, 0.9–1 cm long, outside pale pink and inside white, orifice 0.5–0.6 cm width, throat having two yellow longitudinal honey-guide stripes; adaxial lip 5–7 mm long, 2-lobed, lobes broadly ovate, having 5–6 longitudinal dark bluish purple stripes on each lobe; abaxial lip 5–6 cm long, 3-lobed to near middle, lobes orbicular-ovate, central one longer and oblong, lateral ones obliquely oval, having 3 longitudinal dark bluish purple stripes on each lobe. Stamens 2, adnate to 4–5 mm above the base of the corolla tube, filaments ca. 5 mm long, geniculate from almost the base, dark yellow, glabrous; anthers reniform, irregularly twisted, ca. 1.5 mm long, glabrous. Staminodes 3, lateral ones linear, adnate to 2–3 mm above the base of corolla tube, ca. 1.3 mm long, glabrous, the central one wand-like, adnate to ca. 1 mm above the base of corolla tube, ca. 2 mm long, glabrous. Disc ring-like, ca. 1 mm height. Pistil ca. 13 mm long, ovary ca. 3 mm long, style ca. 10 mm long, ovary densely covered with glandular-puberulent hairs and puberulent hairs, style covered with glandular-puberulent hairs; disc circular, white, ca. 0.8 mm in height, margin entire; stigma cordate, 2-lobed, lobes elliptic, ca. 0.7 mm long, covered with shortly puberulent hairs. Capsule linear, ca. 2 cm × 1–1.5 mm, densely puberulent.

Distribution and habitat:— Primulina cordistigma is known only from the type locality in Yuxisandong, Helang Town, Yangchun city, Guangdong province, China. It grows only in crevices of the shaded moist rock surfaces and cave entrances of limestone hills under subtropical evergreen broadleaved forests, at an elevation ca. 78 m.

Proposed Conservation Red List Category:—At present, only one locality is known, with locally abundant plants. The population is vulnerable to anthropogenic impacts; the habitat of Primulina cordistigma has been gradually degraded by activities linked to tourist developments. Thus, it is proposed that this new plant be considered as ‘Endangered’ (EN A1cd)” using the IUCN Red List categories and criteria ( IUCN 2011).

Phenology:—The new species was observed flowering in October and fruiting in December.

Etymology:—The new species is named for its heart-shape stigma.

Notes:— Primulina cordistigma is morphologically similar to P. yangchunensis Y.L.Zheng & Y.F.Deng in Zheng & Deng (2014: 49) ( Fig. 3 ), from which it differs by having some obvious characters as summarized in table 1, for example, the aspect ratio of two species leaf blades are obviously different, namely the values of P. cordistigma is roughly a ratio of 1.4: 1 to 2: 1, but P. yangchunensis are 2: 1 to 2.3: 1. Furthermore, the number of cymes of P. yangchunensis was not mentioned in the original paper; the stigma of P. yangchunensis Zheng & Deng (2014) at description and Fig 1-F , which was described as oblong with 2 lobes, was too simple to distinguish the word, “oblong”, refers to the shape of one lobe or the entire stigma. Actually, the stigma lobes shape of P. yangchunensis is closer to acute triangle. For P. cordistigma , the shape of entire stigma looks similar to the shape of the heart, but the shape of lobes is elliptic having shortly puberulent hairs. However, there is some erroneous corolla tube measurements given for P. yangchunensis and others (e.g. stigma) showed in Zheng & Deng (2014). For instance, it is impossible that the lengths of corolla and corolla tube have so major variations according to the scales at Fig. 1-A, B, D . In order to compare two congeners more accurately, the some supplementary and corrected description of reproductive organ morphology of P. yangchunensis should have to add.

Figures

FIGURE 1 Primulina cordistigma illustration. A, habit; B, adaxial leaf surface and magnified leaf blade margin showing ciliate hairs; C, flower; D, cut-open corolla showing stamens and staminodes; E, pistil with and with calyx lobes removed; F, stigma; G, filaments with coherent anthers. Drawn by Bi-Dan Lai partly from the holotype (Fig. 2).

FIGURE 2 Primulina cordistigm. A, habitat; B, cluster of plants; C, habit; D, leaves; E, frontal view of flower; F, lateral view of flower; G, cut-open corolla showing stamens and staminodes, H, anthers, I, stigma, J, pistil and pedicel. Photographed by Bi-Dan Lai & Bing- Mou Wang.

FIGURE 3 Primulina yangchunensis. A, habitat;B, leaf blades; C, habit D, frontal view of corolla; E, lateral view of corolla.Photographed by Fang Wen.