PRIMULINA CRASSIRHIZOMA SP . NOV . ( GESNERIACEAE ) FROM A LIMESTONE AREA ALONG THE BOUNDARY OF SINO-VIETNAM

Primulina crassirhizoma F. Wen, Bo Zhao & Xin Hong, a new species from a limestone area along the boundary of Sino-Vietnam, is described and illustrated. It is similar to P. linearifolia and P. longgangensis in leaf and flower shape, but can be distinguished by extremely strong rhozime, with conspicuous internodes, leaf blade adaxial surface nitid, sparsely appressed strigose, lateral veins 6–8 on each side of midrib, calyx narrowly triangular to narrowly ovate, corolla pale purple to bluish purple, c. 3.5 cm long, tube nearly tubular, adaxial lip c. 6 mm, abaxial lip 8-9 mm, glabrous anthers and staminodes 3. Introduction The distribution and differentiation centre of Primulina Hance (Gesneriaceae) located to South and South-west China and North Vietnam (Wei et al., 2010), and many species and varieties of this genus are usually endemic to China, especially in the limestone areas of Guangxi Zhuang Autonomous Region. Very recently some taxa of Primulina Hance have been newly described from Guangxi, China, viz. P. purpurea Fang Wen, Bo Zhao & Y.G Wei (Wen et al., 2012a), P. hochiensis var. rosulata F. Wen & Y.G. Wei (Wen et al., 2012b) and P. fengshanensis Fang Wen & Yue Wang (Wen et al., 2012c). In 2004, Shi-Liang Mo, a tourist first collected some “Primulina”-like plants from Longbang town, Jingxi County, Guangxi, China. Later on, we found this particular unknown species near the top of limestone hills along the boundary of Sino-Vietnam in 2005. After five years, Prof. Hai He and Prof. Li-Bing Zhang collected many specimens of this particular species with flowers from Pingan town, Jingxi County in 2010. Although this unknown taxon looks like Primulina linearifolia (W.T. Wang) Y.Z. Wang (Wang and Pan, 1982; Wang et al., 2011) and P. longgangensis (W.T. Wang) Y.Z. Wang (Wang and Huang, 1982; Wang et al., 2011), we could easily distinguished three species by the characters of leaves and flowers. After consultation of relevant literatures (Wang et al., 1990, 1998, 2011; Li and Wang, 2004; Wei et al., 2010; Weber et al., 2011; Xu et al., 2012), and examination of the specimens deposited in different herbaria (ANU, BJFU, CDBI, HN, IBK, IBSC, KUN, PE, VMN, CTC, MO, CDBI), we concluded it as a new species, Primulina crassirhizoma sp. nov. The new species is described and illustrated here. College of Life Sciences, Anhui Normal University, CN-241000, Wuhu, China. College of Life Sciences, Guangxi Normal University, Guilin CN-541004, China Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and the Chinese Academy of Sciences, CN-541006 Guilin, China. Corresponding author. Email: wenfang760608@139.com


Introduction
The distribution and differentiation centre of Primulina Hance (Gesneriaceae) located to South and South-west China and North Vietnam (Wei et al., 2010), and many species and varieties of this genus are usually endemic to China, especially in the limestone areas of Guangxi Zhuang Autonomous Region.Very recently some taxa of Primulina Hance have been newly described from Guangxi, China, viz.P. purpurea Fang Wen, Bo Zhao & Y.G Wei (Wen et al., 2012a), P. hochiensis var.rosulata F. Wen & Y.G.Wei (Wen et al., 2012b) and P. fengshanensis Fang Wen & Yue Wang (Wen et al., 2012c).
In 2004, Shi-Liang Mo, a tourist first collected some "Primulina"-like plants from Longbang town, Jingxi County, Guangxi, China.Later on, we found this particular unknown species near the top of limestone hills along the boundary of Sino-Vietnam in 2005.After five years, Prof. Hai He and Prof. Li-Bing Zhang collected many specimens of this particular species with flowers from Pingan town, Jingxi County in 2010.Although this unknown taxon looks like Primulina linearifolia (W.T. Wang) Y.Z.Wang (Wang and Pan, 1982;Wang et al., 2011) and P. longgangensis (W.T. Wang) Y.Z.Wang (Wang and Huang, 1982;Wang et al., 2011), we could easily distinguished three species by the characters of leaves and flowers.After consultation of relevant literatures (Wang et al., 1990(Wang et al., , 1998(Wang et al., , 2011;;Li and Wang, 2004;Wei et al., 2010;Weber et al., 2011;Xu et al., 2012), and examination of the specimens deposited in different herbaria (ANU, BJFU, CDBI, HN, IBK, IBSC, KUN, PE, VMN, CTC, MO, CDBI), we concluded it as a new species, Primulina crassirhizoma sp.nov.The new species is described and illustrated here.
Phenology: It flowers from November to early December.Ecology: At least five populations have been found for the new species around the border of China (Tunhong village of Longbang town, Jingxi County, Guangxi) (Fig. 3).Besides, some plants of this new species were introduced and cultivated in Royal Botanic Gardens, Kew in past ten years from Vietnam, but they are lack of specific information of Vietnamese locality, and known only from Cao Bằng province of North Vietnam.All known populations in China are growing at the crevices in evergreen limestone broad-leaved forest or bamboo-bushes near the peak of limestone hills.
Etymology: The specific epithet is derived from its extremely thick and robust rhizome.Note: Primulina crassirhizoma is morphologically similar to P. linearifolia (W.T. Wang) Y.Z.Wang and P. longgangensis (W.T. Wang) Y.Z.Wang, but it differs from these species in having thick and strong rhizome, with conspicuous internodes; adaxial surface of leaf blade nitid, sparsely appressed strigose; lateral veins 6-8 on each side of midrib; calyx narrowly triangular to narrowly ovate; corolla pale purple to bluish-purple, c. 3.5 cm long; tube nearly tubular, adaxial lip c. 6 mm; abaxial lip c. 8-9 mm; filaments ca.0.9-1.1 cm long; anthers glabrous; staminodes 3. The differences of three relatives are shown in Table 1 and Fig.

Fig. 2 A
Fig. 2 A-F.Primulina crassirhizoma F. Wen, Bo Zhao & Xin Hong sp.nov.A) Habitat; B) Habit; C) Cymes and flowers; D) Front view of flower and bud; E) Lateral view of flowers and calyx lobes; F) Pistil; G. Stigma; H. Back of leaf blade; I-L.P. longgangensis I) Habit; J) Cymes and flowers; K) Front view of flower; L) Lateral view of flower and calyx lobes; M-P.P. linearifolia M) Habit; N) Cymes and flowers; O) Front view of flower; P) Lateral view of flower and calyx lobes.