Paraboea dolomitica (Gesneriaceae), a new species from Guizhou, China

Abstract Here we describe Paraboea dolomitica Z.Y. Li, X.G. Xiang & Z.Y. Guo, a new species of Gesneriaceae from Guizhou, China. Based on recent extensive observations, this new species is morphologically similar to Paraboea filipes (Hance) Burtt, in having obovate leaf blades, 1–4-flowered cymes and purplish corolla, but differs from that species by the combination of denticulate leathery leaves, sparsely brown haired peduncles, two woolly bracts, reniform anthers and two glabrous staminodes. Additionally, molecular data support this new species as a member of a clade that includes P. crassifolia, P. tetrabracteata, P. peltifolia, P. vetutina, P. dushanensis, P. dictyoneura, P xiangguiensis and P. guilinensis, but it is distinct from them in leaf position, inflorescence, penduncle, bract and capsule. The conservation status of this species is considered to be “Vulnerable” (VU) according to the IUCN Red List Categories and Criteria.


introduction
Paraboea was published by Clarke (1883) as a section of the Didymocarpus Wall. and subsequently treated as a distinct genus by Ridley (1905). Burtt (1984) recircumscribed Paraboea based on the indumentum instead of fruit morphology, and many species were transferred to Paraboea from the genus Boea Comm. ex Lam. Xu et al. (2008) revised this genus and recognised 89 species and five varieties. Using ITS and trnL-F, a recent molecular phylogenetic study indicated that Trisepalum C.B. Clarke and Phylloboea Benth. were nested in Paraboea, and consequently 15 new combinations in Paraboea were made (Puglisi et al. 2011). Further, Puglisi et al. (2016) established a new genus Middletonia segregated from Paraboea.
To date, Paraboea (C.B.Clarke) Ridley contains approximately 142 species and is distributed in southern China, northeastern India, the eastern Himalayas, Burma, Thailand, Cambodia, Laos, Vietnam, Malaysia, Philippines and Indonesia east to Sulawesi, occurring mostly in limestone regions (Xu and Burtt 1991;Xu 1994;Li and Wang 2004;Xu et al. 2008;Chen et al. 2008;Puglisi et al. 2011;Xu et al. 2012;Wen et al. 2013;Xu et al. 2017a;Puglisi and Phutthai 2018). Xu et al. (2017b) summarised that there are ca. 28 species in China, mainly in limestone areas of south and southwest China. Since then, one new species and one new record have been discovered in China (He et al. 2018;Lu et al. 2019). During our expeditions to Wuyang River, Zhenyuan County and Yuntai Mountain, Shibing County, Guizhou, China in 2016 and 2017, an unidentified species of Paraboea was collected. Based on morphological and molecular data, we concluded that it is a significant new species, which we describe here.

Morphological observations
Morphological observations and measurements of the new species were carried out, based on living plants in the field and dry specimens in herbarium (PE and QNUN, herbarium acronyms according to Index Herbariorum; Thiers 2020). The photographs were taken in the field. All morphological characters were studied under dissecting microscopes and are described using the terminology presented by Wang et al. (1998).

Taxon sampling and DNA sequencing
A total of 60 species of Paraboea were sampled. Based on Roalson and Roberts (2016) and Xu et al. (2017a) Total genomic DNA was extracted from leaves dried in silica gel using the Plant Genomic DNA Kit (CW Biotech, Beijing, China). The nuclear internal trancribed spacer (ITS) and chloroplast trnL UAA -F GAA (including intron and spacer) were used in this study. The primers for ITS were ITS-5P (5'-GGA AGG AGA AGT CGT AAC AAG G-3') and ITS-8P (5'-CAC GCT TCT CCA GAC TAC-3') (Möller and Cronk 1997) and primers for trnL-F were c (5'-CGA AAT CGG TAG ACG CTA CG-3') and f (5'-ATT TGA ACT GGT GAC ACG AG-3') (Taberlet et al. 1991). The selected DNA regions were amplified with standard polymerase chain reaction (PCR) and products were analysed by MajorBio company (Beijing, China). Voucher information and GenBank accession numbers are listed in Appendix 1. Except for sequences of the new species that were generated in this study, others are from GenBank.

Alignment and Phylogenetic analysis
Sequences were aligned using the default parameters in CLUSTAL X v1.83 (Thompson et al. 1997) and manually adjusted with BIOEDIT v5.0.9 (Hall 1999). Phylogenetic analyses were carried out using Maximum Parsimony (MP) and Bayesian Inference (BI) methods in PAUP v4.0b10 (Swofford 2003) and MrBayes v3.2.0 (Ronquist and Huelsenbeck 2003), respectively. For MP analyses, heuristic searches were performed with 1000 random sequence addition replicates, tree-bisection-reconnection (TBR) branch swapping, MulTrees in effect and steepest descent off. Gaps were treated as missing data, characters were equally weighted and their states were unordered. Internal branch support was estimated by using 1000 bootstrap replicates (Felsenstein 1985), as described above. For BI analyses, the nucleotide substitution model was determined by the Akaike Information Criterion (AIC) in Modeltest v3.06 (Posada and Crandall 1998). Four chains of the Markov Chain Monte Carlo (MCMC) were run over 3 million generations, sampling one tree every 1000 generations, starting with a random tree. Majority rule (> 50%) consensus tree was constructed after removing the burn-in period samples (the first 25% of the sampled trees).

Proposed IUCN conservation status
The new species has only been found in Shibing County and Zhenyuan County, Guizhou, China. The populations and habitats are vulnerable to human activities such as road construction and deforestation for crops. According to field observations, it has several known populations of less than 300 mature individuals according to field observations. The species is considered to be "Vulnerable" (VUD1) according to the IUCN Red List Criteria (IUCN 2017), based on Criterion D1 and population size, estimated to be fewer than 1000 mature individuals.