Lobelia hongiana (Campanulaceae), a new species from Guangxi, China

Abstract Lobelia hongiana, a new species of Campanulaceae from Guangxi, South China, is described and illustrated here. This new species is most similar to L. chinensis and L. loochooensis, but differs by its elliptic-obovate or oblanceolate leaf, 2.5–3 mm long greenish-carmine hypanthium, 5 or 6 calyx lobes, purplish-white corolla, with yellowish-green blotches at the base of lower lobes, glabrous filaments, 7–8 mm long broadly obconic capsule. Molecular phylogenetic analysis has been conducted based on ITS and two chloroplast sequences (atpB and rbcL) and 14 taxa in Lobelia are included. L. hongiana is well supported as a new species by the evidence from both morphology and molecular phylogeny.


Introduction
Lobelia Linnaeus (1753: 929) (Campanulaceae) is mainly distributed in tropics and subtropics (Lammers 2011). Wimmer (1943Wimmer ( , 1953Wimmer ( , 1968 proposed the first comprehensive classification system of this genus, which was mainly based on some morphological characters. Subsequently, Murata (1995) and Lammers (2011) improved the classification system using more morphological characters. With over 400 species, Lobelia is the second largest genus in Campanulaceae (Campanula Linnaeus (1753: 163) is the largest one) and it was classified as 18 sections based on the morphological characters and molecular analyses (Lammers 2011;Chen et al. 2016). Of these, there are 23 species (with six endemic species), belonging to five sections, which have been recorded in China (Hong and Lammers 2011).
During a fieldwork in Huixian town of Guangxi Zhuang Autonomous Region in June 2016, some interesting specimens of Lobelia were collected near a local crops field. The leaf shape and flower characters of these individuals were distinctly different from those of the other described Lobelia in China. Besides the collected specimens of this unknown Lobelia, some individuals were also transplanted in the greenhouse of Wuhan Botanical Garden for further observations. Based on careful observation on morphological characters, literature consulting and specimen comparisons, it was found that these specimens should be a new species, belonging to L. sect. Hypsela (C. Presl) Lammers in Hong and Lammers (2011: 555). Morphologically, this new species is similar to L. chinensis Loureiro (1790: 514) as well as L. loochooensis Koidzumi (1929: 406) that is endemic to Okinawa, Japan. A molecular phylogeny using the combined ITS, atpB and rbcL dataset also supported these specimens as a separate species. In this study, therefore, the new species was named as Lobelia hongiana Q.F.Wang & G.W.Hu.  Perry (1949: 59), L. donanensis P. Royen (1966: 305), L. nummularia Lam. (1792: 589), L. victoriensis P. Royen (1978: 118), L. chinensis and L. loochooensis. The taxonomic status of the eight species was examined by checking the type specimens from JSTOR Global Plants (http://plants.jstor.org/) and the protologue.

Phylogenetic analysis
Two individuals were used from Huixian town, Guangxi Zhuang Autonomous Region, China to assess the phylogenetic position. A total of 14 closed taxa as ingroups and one Trachelium species as outgroup were used in phylogenetic analyses. Total genomic DNA was extracted from the fresh material according to Chen et al. (2016). Six sequences from two individuals of the new species were newly generated in this study and the other sequences were downloaded from NCBI (https://www.ncbi. nlm.nih.gov/) ( Table 1). The primers were obtained following Haberle et al. (2009, atpB and rbcL) and Chen et al. (2016, ITS). PCR amplification, sequencing and sequence assembly were implemented following Chen et al. (2016). The best model of nucleotides substitution was selected using jModeltest 2.1.4 (Darriba et al. 2012) with the Akaike Information Criterion (AIC). The Maximum Likelihood (ML) analysis was obtained using RAxML version 8.1.24 (Stamatakis 2006), with separate partitions for the nuclear and plastid data using 1000 bootstrap replicates. The Bayesian Inference (BI) was performed by MrBayes version 3.2.6 (Ronquist and History 2015). Monte Carlo Markov chains were run for 10 million generations with sampling every 5,000 generations. The default setting was used for chain heating (temp = 0.2). The first 10 % of trees were discarded as burn-in and the remaining trees were combined to estimate posterior probability (PP) and other settings following Jin et al. (2016).

Results and discussion
The Bayesian tree showed that the new species is well supported as sister to L. loochooensis (ML bootstrap values = 96, PP = 1.00) which placed it in L. sect. Hypsela. Evidence from molecular phylogeny supports L. hongiana as an independent taxon, with L. loochooensis as the sister taxon. This study also made the supposition that L. sect. Hypsela originated from Australia and dispersed to New Zealand, Ryukyus and Southern China (Kokubugata et al. 2012).
Lobelia hongiana has the following characters, including its solitary flowers in the axils of leaves, a sub-bilabiate corolla with lobes longer than the tube, anthers with a single elongate bristle at the apex of each of the ventral pairs and seed coat reticulate. All of these characters group it into L. sect. Hypsela. In this section, this new species is most similar to L. chinensis and L. loochooensis, but the differences amongst them are also dominant (Table 2). Compared with L. chinensis, it has a smaller leaf, shorter hypanthium, calyx lobe 5 or 6, shorter than hypanthium, purplish-white corolla, corolla lobe not spreading in a plane on anterior side and shorter glabrous filaments. Compared with L. loochooensis, it has a prostrate stem, elliptic-obovate or oblanceolate leaf, longer pedicels, longer greenish-carmine hypanthium, its calyx lobes are shorter than hypanthium, longer corolla, bearing tufts of filiform hairs at 3 dorsal anther tubes and longer broad obconic capsule. Combined with morphological and phylogenetic analyses, L. hongiana is confirmed as new to science.
Phenology. The new species was found in flower from May to July. Etymology. Species epithet, "hongiana", is in honour of Prof. De-Yuan Hong who made a significant contribution to the authors' knowledge of Campanulaceae.
Conservation status. This new species was only found at Huixian Wetland in Guangxi Zhuang Autonomous Region, China, although it might also be distributed in adjacent areas. Until now, about 200 individuals were found in each population. Since there is not enough information on population size and dynamics, an assessment of the current conservation status of this species cannot be given. Therefore, it is suggested that the species be evaluated as Data Deficient (DD) according to the IUCN Red List Categories and Criteria (IUCN 2001).
Other specimens examined (