A new species of Eriobotrya (Rosaceae) from Yunnan Province, China

Abstract Eriobotrya laoshanica, a new species of Rosaceae from Yunnan, China, is described and illustrated. The new species is easily distinguished from the most similar species E. malipoensis K. C. Kuan by its longer petioles (2–5 vs. 0.5–1 cm); indumentum on the lower leaf surfaces (densely tomentose vs. glabrous); much fewer flowers (15- to 30-flowered vs. 50- to 100-flowered) on the panicle; larger flowers (2.5–3 vs. 1.5–2 cm in diameter); and non-angulated (vs. angulated) young fruits.


Introduction
The genus Eriobotrya Lindley, a small genus of subtribe Malinae (tribe Maleae, subfamily Amygdaloideae, Rosaceae) consisting of approximately 30 species, is distributed in Himalaya, eastern Asia and western Malesia (Vidal 1965;Gu and Spongberg 2003;Mabberley 2017). This genus is considered close to Rhaphiolepis based on the shared characters of larger seeds and thinner endocarp (Robertson et al. 1991). Recent studies based on molecular evidence strongly supported the Eriobotrya-Rhaphiolepis clade (Lo and Donoghue 2012;Xiang et al. 2016). Eriobotrya japonica (Thunberg) Lindley, commonly known as loquat, is an important fruit tree cultivated throughout southeastern Asia and southern Europe (Gu and Spongberg 2003).
There are about 16 Eriobotrya species (five endemic) recorded in China (Gu and Spongberg 2003;Yang and Lin 2007;Li et al. 2012). Among them, there are only four species and one natural hybrid species flowering in autumn and winter, namely, E. × daduheensis H. Z. Zhang (Gu and Spongberg 2003;Ding et al. 2015). In our investigations into Eriobotrya species in Yunnan province of China, a distinct Eriobotrya species flowering in autumn was collected in 2015. After four years' field observations and comprehensive literature studies, we confirmed it was a new species and it is described and illustrated here.

Materials and methods
Morphological observations of the putative new species and its close relatives were carried out based on living plants in the field as well as dried specimens. All morphological characters were measured using a stereomicroscope with ocular micrometer (Leica S8APO, Leica Microsystems Inc., Germany). The voucher specimens were deposited in the herbarium of Sun Yat-sen University (SYS) and the herbarium of South China Botanical Institute (IBSC).
Leaf samples for the putative new species were collected and stored in silica gel. The total DNA was extracted with the TIANamp Genomic DNA Kit [TIANGEN Biotech (Beijing) CO. Ltd] according to the protocol procedure, and then sent to Novogene Bioinformatics Technology (Beijing, China) Co. Ltd for quality inspection and low-coverage genome sequencing using Illumina 2000 platform following the standard Illumina sequencing procedure. Approximately 6 GB cleaned raw data was produced and assembled into circled chloroplast genomes with the perl script NOVO-Plasty2.7.2 (Dierckxsens et al. 2017; accession numbers: MT130714, MT130715), using the chloroplast genome and the rbcL gene of E. japonica (downloaded from NCBI website, accession number: NC_034639.1) as reference and seed, respectively. Then the two assembled sequences were annotated on online GeSeq (Tillich et al. 2017) with the same reference of E. japonica (accession number: NC_034639.1). Further, complete chloroplast genome sequences for Eriobotrya, and other close genus such as Rhaphiolepis, Heteromeles, Cotoneaster, and Photinia were downloaded from the NCBI nucleotide database (Zhang et al. 2017). Together with the putative new species, all the chloroplast genomes were aligned with MAFFT version 7 (Rozewicki et al. 2019) and then manually checked and revised with MEGA version 6.0 (Tamura et al. 2013). The phylogenetic tree was then constructed with IQ-Tree 1.6.10 (Nguyen et al. 2015) based on the maximum likelihood method, in which the best-fit model of DNA substitution was auto-determined by calculating the Bayesian Information Criterion (BIC) using the 88 available nucleotide substitution models, ultrafast bootstrap was set as 2000, and Photinia species were set as outgroup.

Molecular analyses
The alignment length of these twenty-five chloroplast genomes was 166,363bp in total, with the statistics of 1,307 parsimony-informative sites. No variable sites were detected between the two accessions of the new species but 139 variable sites were detected between the new species and E. malipoensis. This low diversity within the species was also observed in E. japonica (KT633951 was also identical to NC_034639, KY085905 identical to MN577877).The best-fit nucleotide substitution model was detected as TVM+F+R2 based on Bayesian Information Criterion (BIC). The ML phylogenetic tree ( Fig. 1) showed that all the Rhaphiolepis species formed a well-supported clade (clade A) that is sister to a clade of Eriobotry species (clade B) and the sister group relationship of these two clades is well supported; E. henryi, E. obovata, E. salwinensis and E. seguinii clustered together forming the clade B; the clade A and B formed a sister relationship; the putative new species, E. laoshanica is placed into a well-supported clade with E. malipoensis and E. calaleriei, and then clustered with E. japonica and E. deflexa forming the clade C.    (Figs 2, 3) Diagnosis. This species is similar to E. malipoensis and E. serrata, but differs from them in its leaf shape, indumentum on the lower leaf surfaces, longer petioles, much fewer flowers on the panicle, larger flowers, and other traits.
Phenology. Flowering from September to October, fruiting from November to December.
Etymology. The specifc epithet refers to Laoshan Mountain, the locality of the type collection.
Distribution and habitat. Eriobotrya laoshanica is currently known only from two localities in Laoshan Natural Reserve, Malipo County, southeastern Yunnan, China. Here, the species is distributed in thin forests on the slopes of limestone hills at al-

Conservation status.
Only two populations were found with no more than 50 mature individuals in a total area of about 5 km 2 . It's about 6.5 km away between the two populations. The wood of this species is very suitable for firewood. During the expedition in 2019, we found that at least two big trees about 15 cm in diameter were felled by the local villagers. Thus the species could be considered as CR (Critically Endangered) status according to IUCN Red List criteria (B2ab(v); IUCN 2019).
Additional specimens examined (