Primulina jiuyishanica (Gesneriaceae), a new species from Hunan, China

Abstract Primulina jiuyishanica K. Liu, D.C. Meng & Z.B. Xin, a new species of Gesneriaceae from Hunan, China, is described and illustrated. The new species is morphologically similar to Primulina fimbrisepala (Hand.-Mazz.) Yin Z. Wang, but differs in its elliptic to broadly elliptic leaf blade with broadly cuneate base, peduncle densely pubescent with sparse glandular hairs, corolla throat with no purple spots inside, the yellow patch in the throat densely glandular-pubescent and pistil densely glandular-pubescent. Photographs and descriptions of the new species are provided below.


Introduction
Since the original monotypic genus Primulina was redefined in 2011 (Wang et al. 2011;Weber et al. 2011), many taxa new to science have been published by taxonomists and researchers, making it the largest genus of the Chinese Gesneriaceae (Wen et al. , 2020Möller 2019). For instance, a total of 9 new species and one variety of Primulina were published in 2019, including P. purpureokylin F. Wen Kong & L.H. Yang (Konget al. 2019). As this trend persists, more new species will likely be discovered in the near future (Möller 2019). Primulina, which mainly grows in limestone areas, are found only in southern and southwestern China and northern Vietnam (Möller et al. 2016). In all, 197 species and 27 varieties of Primulina exist at present, including 183 species and 27 varieties recorded from China and 21 species recorded from Vietnam (Hộ 2000;Burtt 2002;Weber et al. 2011;Möller et al. 2016;IPNI 2020;Wen et al. 2020).
In 2016, one of the authors (LK) discovered some plants in the Jiuyishan National Nature Reserve, Hunan Province, China, which possibly represented an undescribed species. Some living plants were mailed to the Gesneriad Conservation Center of China (GCCC) for observation and conservation. Those living individuals were introduced and cultivated in the gardens of the GCCC, and the lead author continuously monitored the population in the wild for several years. A detailed comparison of these specimens and living plant materials with the type specimens and protologues of known Primulina species revealed that these specimens neither fit the existing protologues nor conform to the type specimens of these species. Nevertheless, the inflorescence, shape and color of the corolla, stamens and staminodes are most similar to those of P. fimbrisepala (Hand.-Mazz.) Yin Z. Wang. It can be distinguished from the latter by a combination of several morphological characters of the leaf blade, peduncle, corolla throat and pistil. Thus, we confirmed that it represents a new species of Primulina, and described and illustrated it here. The description, illustration, information on ecology, phenology, and provisional conservation assessment by using IUCN categories and criteria (2019) of the proposed new species are also provided.

Methods
The plant material for description was collected in the field at its type locality in 2017. Morphological observations and dissections of plant material of this new species were made under a stereoscopic microscope and measured and described using the terminology used by Wang et al. (1998). The literature examined included related monographs and papers (e.g., Wood 1974;Wang et al. 1998;Li and Wang 2004;Weber 2004;Haston and De Craene 2007;Chen et al. 2008;Wei et al. 2010). Specimens stored in herbaria in China, Vietnam, the United States and the United Kingdom (E, GH, HN, IBK, K, KUN, MO, PE, PH, US and VNMN) were examined.

Conservation status.
The EOO and AOO of Primulina jiuyishanica are 54.28 km 2 and 5.2 km 2 respectively. So far, only eight populations of this species were found located in a nature reserve. However, we believe that more populations will be found in the future, and the EOO and AOO might increase. The eight populations have in total more than 3000 mature plants in the type locality, and additionally many seedlings were found. The plants are well protected in the nature reserve. According to the guidelines for using the IUCN Red List Categories and Criteria (IUCN 2019), the new species should be assessed as of Least Concern (LC).
Note. In figure 2, A