Primulina flexusa F. Wen, Tao Peng & B. Pan, 2020

Peng, Tao, Pan, Bo, Maciejewski, Stephen & Wen, Fang, 2020, Primulina flexusa sp. nov. (Gesneriaceae) from Guizhou Province, China, PhytoKeys 159, pp. 61-69 : 61

Primulina flexusa F. Wen, Tao Peng & B. Pan sp. nov. Figures 1 , 2

Type.

China. Guizhou Province, Duyun City, Bamang town, Longtang village, 26.31N, 107.49E, altitude ca. 1040 m, 15 May 2016, Bo Pan et al., PB160425-01 (Holotype: IBK!; Isotype: IBK!).

Diagnosis.

The new species resembles Primulina curvituba in having a curved corolla but is easily distinguished from the latter by bracts oblong (vs. lanceolate), filament glabrous (vs. glandular-pubescent), ovary ovoid (vs. cylindrical), stigma slightly 2-parted at the apex (vs. undivided at apex) and capsule ovoid (vs. linear).

Description.

Herbs perennial, acaulescent. Leaves basal, 8-12, opposite, petiolate; petiole compressed, gradually broadened from the base to the upper, densely pilose, 5-13 × 1.5-3.5 mm; leaf blade ovate to broadly ovate, abaxial surface green to dark green, adaxial surface brownish-green to brownish-purple; 1.6-2.0 × 1.3-1.8 cm, pubescent and pilose on adaxial surface, puberulent on abaxial surface, base shallowly cordate to slightly cuneate, margin entire and ciliate, apex obtuse to nearly rounded; lateral veins ca. 3 on each side of the midrib, inconspicuous on adaxial surface, prominent on the abaxial surface. Cymes 2-4, 1-4-flowered; peduncle 1.5-2.4 cm long, ca. 1 mm in diameter, erect pubescent; bracts 2, opposite, oblong, ca. 3.8 × 0.7 mm, adaxially green and nearly glabrous, abaxially brownish-green to brownish-purple, densely pilose, the pilose hairs 0.8-1.2 mm long, margin entire, apex acute, bracteole ca. 2.4 × 0.5 mm, color and indumentum same as bracts. Pedicel 6.5-8 mm long, ca. 0.9 mm in diameter, puberulent. Calyx 5-parted from the base; segments equal, pale brown to brown, lanceolate, 4-5 × 0.7-0.9 mm, outside pale brown to greenish-brown, densely pubescent, inside greenish-brown, glabrous, margin entire, apex acute. Corolla 21-25 mm long, pale purple to purple, throat with two distinctly dark purple stripes respectively between each pair of abaxial lip lobes, outside covered with extremely short glandular-puberulent hairs, inside nearly glabrous; corolla tube infundibuliform, slightly curved downwards at base (ca. 4 mm from the base), then gradually bent forwards, 16-19 mm long, ca. 6 mm in diameter at the mouth, ca. 2.5 mm in diameter at the base; limb distinctly 2-lipped, adaxial lip 2-parted over 2/3 from the top of the adaxial lip, lobes nearly equal, broadly obovate, ca. 5 × 4 mm; abaxial lip 3-parted over 4/5 from the top of the abaxial lip, lobes slightly obliquely obovate, 7.5-8 × 3.9-5 mm. Stamens 2, adnate to ca 2.5 mm above the corolla base; anthers pale yellowish-brown, elliptic, ca. 1.5 × 1.0 mm, fused by entire adaxial surfaces; filaments linear, straight, ca. 3 mm long, white, glabrous; staminodes 3, adnate to ca. 3 mm above the corolla tube base, lateral ones ca. 3.5 mm long, the middle one ca. 0.7 mm long. Disc yellowish-green, annular, margin entire or sometimes slightly erose, ca. 0.4 mm high. Pistil ca. 5 mm long; ovary brownish-red, ovoid, ca. 1.4 mm long, ca. 0.9 mm in diameter, densely puberulent and glandular-puberulent; style white, 2.2-2.5 mm long, ca. 0.2 mm in diameter, sparsely glandular-puberulent. Stigma 1, translucent to white, its upper lobe lacking, lower lobe obtrapeziform, slightly 2-parted at apex, ca. 1 mm long, ca. 0.75 mm wide. Capsule ovoid, ca. 6.5 mm long, ca. 2.2 mm in diameter, densely puberulent.

Phenology.

Flowering occurs from April and fruiting from May to June.

Etymology.

The specific epithet ' flexusa ' is derived from its curved corolla tube. The original epithet ' flexusa ' derived from the Latin, ' flexus ', means curved and slightly zigzagging.

Vernacular name.

Qū Guǎn Bào Chūn Jù Tái (Chinese pronunciation); 曲管报春苣苔 (Chinese name).

Distribution and habitat.

Primulina flexusa is hitherto only known from the type locality, Mangba town, Duyun City, Guizhou Province, Southwest China, growing on moist and shaded rocky crevice on the cliff in a subtropical evergreen seasonal rain forest, at an altitude of ca. 1040 m. All plants were growing in a damp and dark crevice of Karst cliff near a village.

Conservation status and IUCN RedList category.

Only a single population with ca. 100 mature individuals is known to exist at the type locality. All individuals were found growing in a large horizontal crevice close to the hillside of the limestone hill. The hill is isolated by maize fields. We, therefore, assess Primulina flexusa as Critically Endangered (CR C1), according to IUCN RedList Categories and Criteria ( IUCN 2019). The CR category assessment of this new species is based on the distributional range that extends ca. 5 km2 around the type locality at present, as observed in the past two years.

Additional specimens examined.

Primulina curvituba B. Pan, L.H. Yang & M. Kang, China: Guangdong Province, Guangzhou City, cultivated in South China Botanical Garden, introduced from Guangxi Zhuangzu Autonomous Region, 25°11'31.83"N, 108°14'52.41"E, growing on the moist rock surfaces of limestone hills, 29 Jul 2016 (flowering), Li-Hua Yang, YLH368 (holotype: IBSC!). Primulina tenuituba (W.T. Wang) Y.Z. Wang, China: Hunan Province, Yongshun County, Qingtianping, growing on the limestone cliff, 14 April 2013, Hong-Wen Huang 40826 (CSFI!);Hunan Province, Longshan County, no detailed information, 11 April 2013, Dai-Ke Tian, Yan Xiao, Yue Chen LS-1310 (CSH!); Hunan Province, Suining County, Huangsang National Natural Reserve, Huangsang Village, Dawanpeng, 413 m a.s.l., 20 April 2014, Jian-Jun Zhou & Zong-Ping Song 1404145 (CSFI!); Hunan Province, Suining County, Huangsang National Natural Reserve, Pingxi Village, Banchong, 894 m a.s.l., 3 May 2014, Jian-Jun Zhou & Zong-Ping Song 1405039 (CSFI!); Hunan Province, Suining County, Huangsang National Natural Reserve, Chiban Village, Yuanyang, 461 m a.s.l., 7 April 2013, Jian-Jun Zhou & Dian Zhou 13024 (CSFI!); Hunan Province, Suining County, Huangsang National Natural Reserve, Dawantang Village, Da, 410 m a.s.l., 11 April 2013, Jian-Jun Zhou & Dian Zhou 13136 (CSFI!); Hunan Province, Suining County, Huangsang National Natural Reserve, Chiban Village, Yuanyang, 487 m a.s.l., 11 April 2013, Jian-Jun Zhou & Dian Zhou 13121 (CSFI!); Guizhou Province, Tongren City, Yangtou District, Jiulongdong, growing on the surface of rocks, 8 July 1988, Wulingshankaochadui 1577 (PE!); Guizhou Province, Guiyang City, Dongshan, growing in the crevices of limestone hill, 8 May 1991, De-Yuan Chen & Cheng-Gang Hu, s.n. (PE!); same locality, 21 May 1989, De-Yuan Chen, s.n. (PE!); Sichuan Province, Daxian County, Pingchang, Heishui, 600 m a.s.l., 1 June 1978, Pingchangdui 212 (SM!); Sichuan Province, Bazhong City, Daluo, Shedan, 700 m a.s.l., 8 March 1979, Bazhongpuchadui 879 (SM!); Sichuan Province, Dazhu County, Zhuqi, Sanqi, Zhongfeng, 9 September 1978, Dazhuxian 0803 (SM!); Sichuan Province, Nanjiang County, Yangba, 28 August 1978, 949 (SM!); Sichuan Province, Xiushan County (Chongqing City now), Shitang, 370 m a.s.l., 17 May 1979, 0349 (SM!).

Notes.

This new species is closely related to Primulina curvituba (Figure 3A ), from which its vegetative and reproductive organs are obviously different, as stated in the diagnosis. The new species also resembles P. tenuituba ; however, the latter has no curved corolla tube (Figure 3B ). The detailed morphological differences among the three species are summarized in Table 1 .

Figures

Figure 1. The flowering plants of Primulina flexusa growing in the crevice of limestone hill (type locality): A-D flowering plants from different aspects.

Figure 2. Primulina flexusa sp. nov. A habitat B habitat and flowering plant for showing curved corolla tube C adaxial surfaces of leaves D abaxial surfaces of leaves E cultivated potted plant in flowering F cyme G adaxial surfaces of bract (right) and bracteole H lateral view of corolla for showing curved corolla tube I opened corolla J calyx lobes K pistil L stigma M mature capsule.

Figure 3. A Primulina curvituba B P. tenuituba: 1 cultivated plants in flowering 2 frontal view of corolla 3 lateral view of corolla for showing the curved and straight corolla tube.