Sorbus lushanensis Xin Chen & Jing Qiu, 2019

Qiu, Jing, Zhao, Yang, Qi, Qi & Chen, Xin, 2019, Sorbus lushanensis, a new species of Rosaceae from China, PhytoKeys 119, pp. 97-105 : 98-102

Sorbus lushanensis Xin Chen & Jing Qiu sp. n. Figures 1 , 2 , 3

Type.

China. Jiangxi: Lushan City, Lushan National Park, Xianren Cave, 993 m alt., 29°34'06.24"N, 115°57'42.84"E, 05 May 2018, J. Qiu 1219 (holotype NF-2005029!; isotypes NF-2005027!, NF-2005028!, NF-2005030!, NF-2005031!, NF-2005032!, NF-2005033!, NF-2005034!, NF-2005035!)

Diagnosis.

Sorbus lushanensis is morphologically most similar to S. folgneri (C. K. Schneid.) Rehd., but differs by its leaf blade abaxially greenish-grey tomentose, stipules smaller, pedicels longer, petals larger and styles glabrous.

Description.

Tree up to 12 m tall, 14.6 cm in DBH; bole straight, bark grey to dark grey, smooth when young, with fissures, particularly at the base of trunk when mature. Branchlets greyish-brown, sparsely tomentose when young, glabrous or glabrescent at maturity, with pale brown to ochraceous lenticels. Buds turbinate or ovoid, pointed; scales reddish-brown, with white pubescent along margins. Leaves simple; stipules scale-like, 1-1.5 mm long, early deciduous; petiole (9 –)13– 16 (-19) mm long, greenish-grey tomentose; blades elliptic to broadly ovate, 5.9-9.2 cm long, (3 –)4– 5.6 cm wide, base cuneate to subcordate, apex acute to shortly acuminate, margin serrate to double serrate, densely greenish-grey tomentose abaxially, sparsely white tomentulose when young, gradually glabrous or glabrescent adaxially; venation craspedodromous, secondary veins 11-16 pairs, slightly impressed adaxially, raised abaxially. Inflorescence a compound corymb, terminal or axillary in the terminal 1-3 leaves, loosely 11 –17(– 26)-flowered; peduncles 3.9-6 cm long, pedicels 9.4-18.6 mm long, both sparsely white vilous. Flowers 12.5-14.2 mm in diam.; hypanthium campanulate, sparsely white vilous abaxially; sepals triangular-ovate, apex acute, 2.3-3.1 mm long, 2-2.9 mm wide, white vilous on both sides; petals white, broadly ovate or sub-rounded, apex obtuse, 5.9-7.1 mm long, 4-6.1 mm wide, glabrous, with a short claw at base. Stamens 17-20, 4.9-6.2 mm long, filaments whitish, anthers cream white to slightly yellow. Ovary 2-loculed, white tomentose apically. Styles 2, 3.1-4.6 mm long, connate to 1/3-1/2 of their length, glabrous. Infructescence glabrous, with numerous lenticels. Fruit orange-red, oblong to ovoid-oblong, 7.8-11.3 mm long, 4.2-7 mm in diam., 2-loculed, sparsely lenticellate, with an annular scar of the deciduous sepals and white tomentose inside it apically. Seeds brown, 5.46-6.48 mm long, 2.88-3.62 mm in diam., 2.04-2.72 mm thick.

Phenology.

Flowering from late April to early May, fruiting from September to October.

Etymology.

The name “lushanensis” refers to the type locality, Lushan Mountain, Jiangxi Province, China.

Vernacular name.

庐山花楸 (lu shan hua qiu).

Distribution, ecology and conservation status.

Sorbus lushanensis is presently known only from Anhui and Jiangxi provinces (Figure 4 ). It was observed growing in broad-leaved and mixed conifer broad-leaved forests at altitudes between 853 m and 1354 m, together with S. alnifolia (Siebold & Zucc.) K. Koch and S. folgneri from the same genus and Pinus taiwanensis Hayata, Carpinus cordata var. chinensis Franch., Cornus kousa subsp. chinensis (Osborn) Q. Y. Xiang, Cyclobalanopsis glauca (Thunb.) Oerst., Fraxinus chinensis Roxb., Litsea elongata (Nees ex Wall.) Benth. & Hook. f., Prunus serrulata Lindl. etc. Its natural habitat is at core Lushan National Park and Tiantangzhai National Nature Reserve, which are perfectly protected. No threats were identified though only about 26 individuals were found along the collection routes. The diameter of individuals ranged from 1.5 to 14.6 cm, denoting the species regenerated well naturally. Adequate data on its distribution and population status need to be further collected for we investigated just along the tourist route without entering the inner forest. At present, we assign the conservation status of S. lushanensis as "Data Deficient (DD)" following the IUCN Red List Criteria and Categories ( IUCN 2017).

Additional specimens examined.

China. Anhui: Lu’an City, Tiantangzhai National Nature Reserve, 853 m alt., 31°09'00.84"N, 115°46'07.39"E, 8 May 2015, W. Du & F. Wang 0125 (NF). Jiangxi: Lushan City, Lushan National Park, Wulao Peak, 1354 m alt., 29°32'52.23"N, 116°00'47.78"E, 14 May 2016, X. Chen, X. X. Fu & Q. L. Liu 0285 (NF); Wulao Peak, 1334 m alt., 29°33'04.00"N, 116°00'56.31"E, 14 May 2016, X. Chen, X. X. Fu & Q. L. Liu 0289 (NF); Wulao Peak, 1246 m alt., 29°33'14.84"N, 116°00'57.31"E, 14 May 2016, X. Chen, X. X. Fu & Q. L. Liu 0298 (NF); Wulao Peak, 1210 m alt., 29°33'17.49"N, 116°00'54.14"E, 14 May 2016, X. Chen, X. X. Fu & Q. L. Liu 0302 (NF); Wulao Peak, 982 m alt., 29°33'16.12"N, 116°00'49.56"E, 14 May 2016, X. Chen, X. X. Fu & Q. L. Liu 031 6 (NF); Wulao Peak, 1234 m alt., 29°33'15.88"N, 116°00'56.26"E, 25 April 2015, X. Chen & W. Du 0069 (NF); Wulao Peak, 1089 m alt., 29°33'23.85"N, 116°00'48.32"E, 10 May 2015, W. Du & F.wang 0085 (NF); Wulao Peak, 1306 m alt., 29°32'52.74"N, 116°00'40.44"E, 15 October 2015, X. Chen, W. Q. Liu; M. W. Geng 0154 (NF); Wulao Peak, 1101 m alt., 29°33'19.14"N, 116°00'49.64"E, 15 October 2015, X. chen, W. Q. Liu & M. W. Geng 0155 (NF); Wulao Peak, 1310 m alt., 29°32'58.59"N, 116°00'46.29"E, 15 October 2015, X. chen, W. Q. Liu & M. W. Geng 0157 (NF); Sandie Spring, 1021 m alt., 29°33'36.10"N, 116°00'49.59"E, 25 April 2015, X. Chen & W. Du 0063 (NF); Sandie Spring, 927 m alt., 29°33'49.98"N, 116°00'56.31"E, 25 April 2015, X. chen & W. Du 0064 (NF); Sandie Spring, 897 m alt., 29°33'52.56"N, 116°01'19.04"E, 15 October 2015, X. Chen, W. Q. Liu & M. W. Geng 0156 (NF); Sandie Spring, 983 m alt., 29°33'35.62"N, 116°00'49.31"E, 15 October 2015, X. Chen, W. Q. Liu & M. W. Geng 0158 (NF); Xianren Cave, 987 m alt., 29°34'06.06"N, 115°57'42.78"E, 14 May 2016, X. Chen, X. X. Fu & Q. L. Liu 0267 (NF).

Discussion.

Morphological characters, such as sepals persistent or deciduous, leaves glabrous or with white or brown hair, venation craspedodromous or camptodromous, styles free or connate, are of taxonomic significance and useful in classification and delimitation of simple-leaved Sorbus taxa ( Hedlund 1901, Yu and Lu 1974, Gabrielian 1978, Lu and Spongberg 2003, Aldasoro et al. 2004). In the latest revision of simple-leaved species of Sorbus ( Aldasoro et al. 2004), species in China are assigned to one subgenus and five sections. The new species is morphologically a member of S. subg. Aria Persoon sect. Alnifoliae (Yu) Aldasoro et al., for it shares the common characters of this section, such as craspedodromous venation, spreading and white petals, coalescent styles and red pomes. Sorbus sect. Alnifoliae contains five species: S. alnifolia , S. japonica (Decne.) Hedl., S. zahlbruckneri C. K. Schneid., S. yuana Spongberg and S. folgneri , mainly distributed in China, Japan and Korea ( Aldasoro et al. 2004). The new species is morphologically similar to S. folgneri in leaf form (Figure 5 ) and the difference between the two species is summarised in Table 1 .

Sorbus lushanensis and the two sympatric species, S. alnifolia and S. folgneri are all diploid (2n=2x=34) sexual species (Chen et al. unpubl. data). Our preliminary molecular work, based on two chloroplast gene fragments, atpB-rbcL and trnL and four nuclear gene fragments, GBSSI, PGIP, PPO and WD, resolved that S. lushanensis formed as sister to S. alnifolia var. angulata S. B. Liang and they two together were resolved as sister to S. folgneri , suggesting that S. lushanensis is not most closely related to S. folgneri (Chen et al. unpubl. data). The new species can be distinguished from the other five species by its abaxially greenish-grey tomentose laminae.

Figures

Figure 1. Holotype of Sorbus lushanensis sp. n. Scanned by Xiaochen Zhang.

Figure 2. Sorbus lushanensis sp. n. A habit (A plant at Wulao Peak, Lushan National Park, Jiangxi province) B flowering branch and leaves (from the plant of type specimen) C young inflorescence (from the same plant as habit).

Figure 3. Sorbus lushanensis sp. n. A flower branch and leaves B flower C petal D styles E stamens F fruit G seed. Drawn by Yuxuan Bao.

Figure 4. Geographic distribution of Sorbus lushanensis sp. n. Drawn by Junsheng Shu.

Figure 5. Leaf abaxial surface of A Sorbus lushanensis and B S. folgneri, show the similar of leaf form and the differences of hairs.