Sorbus megalocarpa Rehder, Pl. Wilson. 2(2): 266. 1915.

Chen, Xin, Ma, JianHui & Geng, LiYang, 2022, Taxonomic notes on Sorbus megalocarpa (Rosaceae) and related taxa, PhytoKeys 201, pp. 131-138 : 131

1. Sorbus megalocarpa Rehder, Pl. Wilson. 2(2): 266. 1915.

Aria megalocarpa ≡ Aria megalocarpa (Rehder) H. Ohashi et Iketani, J. Jap. Bot. 68(6): 359. 1993.

Micromeles megalocarpa ≡ Micromeles megalocarpa (Rehder) Mezhenskyj, NULESU Coll. Fruit Ornament. Pl.: 34. 2018.

Wilsonaria megalocarpa ≡ Wilsonaria megalocarpa (Rehder) Rushforth, Phytologia 100(4): 241. 2018.

Sorbus megalocarpa cuneata = Sorbus megalocarpa var. cuneata Rehder, Pl. Wilson. 2(2): 267. 1915. Type: CHINA. Sichuan: Western Szechuan, Mupin, 2400-2700 m, 10 October, 1910-11, E.H. Wilson 4215 (lectotype, designated by Aldasoro et al. 2004, pg. 43: K[K000758157]; isolectotype: A[A00112653])

Aria megalocarpa cuneata = Aria megalocarpa var. cuneata (Rehder) H. Ohashi et Iketani, J. Jap. Bot. 68(6): 359. 1993.

Sorbus guanxianensis = Sorbus guanxianensis T.C. Ku, Bull. Bot. Res., Harbin 10(3): 22, f. 2. 1990. syn. nov. Type: China. Sichuan: Guanxian (Dujiangyan), 2000 m, 25 August 1987, T.Z. Fu et al. 872102 (holotype: PE[PE00020830]), syn. nov.

Micromeles guanxianensis = Micromeles guanxianensis (T.C. Ku) Mezhenskyj, NULESU Coll. Fruit Ornament. Pl.: 34. 2018. syn. nov.

Wilsonaria guanxianensis = Wilsonaria guanxianensis (T.C. Ku) Rushforth, Phytologia 100(4): 241. 2018. syn. nov.

Type.

China. Sichuan : Western Szechuan , Hung-yah Hsien (Hongyaxian), 1200 m, 12 September 1908, E.H. Wilson 956 (lectotype, designated by Gabrielian 1978, pg. 220: K[K000758158]; isolectotypes: A[A00112650], E[E00147452], GH[GH00112651], US [ US 00097467]) .

Notes.

Sorbus megalocarpa : Sorbus megalocarpa was first published by Rehder (1915: 266). It was transferred to genera Aria , Micromeles and Wilsonaria by Ohashi and Iketani (1993: 359), Mezhenskyj ( Mezhenska et al. 2018: 34) and Rushforth (2018: 241) respectively.

Three gatherings collected by Wilson under number “956” were cited in the protologue. The first one was collected at alt. 2200-2600 m., Mupin, in October 1910; the second one was collected at alt. 1200 m., Hung-ya Hsien, on September 12, 1908; and the third one was collected at alt. 2000 m., Mon-kong Ting, on June 19, 1908. Since the author did not indicate holotype for the name, the three gatherings are syntypes according to the Article 9.6 of the International Code of Nomenclature for algae, fungi and plants (Shenzhen Code) ( Turland et al. 2018). Gabrielian (1978) designated the specimen at K (K000758158; as shown in fig. 1A, plate 62 of Gabrielian 1978), collected from Hung-Ya Hsien, as the lectotype. Four duplicates (A00112650, E00147452, GH00112651, US00097467) out of the eight specimens of " E. H. Wilson 956 " traced at A, E, GH, K and US, are the isolectotypes here.

Sorbus megalocarpa var. cuneata : Rehder (1915: 267) differentiated Sorbus megalocarpa var. cuneata from S. megalocarpa var. megalocarpa by its "smaller softer fruit" ("fructibus minoribus ovovides circiter 1.5 cm. longis et 1 cm. diam." and "the more cuneate short-stalked leaves" ("petiolum vix 1 cm"). This variety was recognized by Yü and Lu (1974) and Lu and Spongberg (2003), was transferred to Aria by Ohashi and Iketani (1993: 359) and was treated as a synonym of S. megalocarpa by Aldasoro et al. (2004). The great variability of leaves and fruits of S. megalocarpa was well documented by Aldasoro et al. (2004) and confirmed in our field investigations (Fig. 1B-D ). Sorbus megalocarpa has elliptic, elliptic-obovate, obovate-oblong leaves with crenate-serrate margins and petiole of 0.7-2 cm long, and large ovoid, ovoid-globose, or sub-globose fruits (1-2.7 cm long, 0.7-2.2 cm in diameter) covered with dense lenticels. The length of petiole and size of fruits of S. megalocarpa var. cuneata are within the variation range of S. megalocarpa . Therefore, we agree with Aldasoro et al. (2004) in reducing S. megalocarpa var. cuneata to a synonym of S. megalocarpa .

Sorbus guanxianensis : Ku (1990: 22) published Sorbus guanxianensis based on two gatherings, " T. Z. Fu et al 2102 " (Fig. 2A ) and " Z. L. Zhao 0970 ". In the protologue, Ku (1990) included the diagnostic words "calycis lobi mox decidui", compared it with S. alnifolia (Siebold and Zuccarini) K. Koch in Sorbus sect. Micromeles and differed it by its larger fruits (about 1.5 cm long), though she assigned it to Sorbus sect. Aria ( Ku 1990). This contradictory taxonomic description led later authors to treat S. guanxianensis in different circumscriptions. Phipps et al. (1990) and Lu and Spongberg (2003) accepted it. Mezhenska et al. (2018: 34) and Rushforth (2018: 241) also recognized it and transferred it to Micromeles and Wilsonaria respectively. Aldasoro et al. (2004) considered it "a doubtful species" and stated that pomes of S. guanxianensis "without lenticels" and "may by a synonym of S. zahlbruckneri ".

No specimens of Sorbus guanxianensis other than the two gatherings cited in the protologue are available in herbarium. Our examination of the type specimens indicated that characters such as persistent calyx and dense lenticels on pomes were in serious conflict with the description in the protologue and were neglected by Aldasoro et al. (2004). Sorbus guanxianensis could easily be distinguished from S. zahlbruckneri C. K. Schneider by the leaves which have margins "singly dentate (not double-dentate)" as stated by Aldasoro et al. (2004) themselves. The unusual characters possessed by the type specimens were noted by Rushforth (2018) who stated that S. guanxianensis "seems to match Rehder’s S. megalocarpa var. cuneata " and transferred it to Wilsonaria together with S. megalocarpa . Morphological similarities (Styles 3 or 4, leaves glabrous or sparsely hair when young, not tomentose, fruit brown, 12-20 mm in diameter, covered in massed contiguous lenticels) stated by Rushforth (2018), and a detailed critical read of the protologues and evaluation of the specimens confirmed that S. guanxianensis is conspecific with S. megalocarpa . Accordingly, we proposed to reduce S. guanxianensis as a heterotypic synonymy of S. megalocarpa here.

Representative specimens examined.

China. Sichuan: Baoxin county, 17 July 1925, K.L. Chu 3149 (IBSC); Dayi county , Xiling town , Chadiping, Xiling Snow Mountain , 30°38'24.84"N, 103°09'52.33"E, 1471 m, 1 June 2015, J.D. Ya and X. J. Hu 15CS11089 (KUN); Dujiangyan, Hongkou town , Dashuigou conservation station, 1250 m, D.H. Zhu, C. Zhang, X.J. Li 4872 (WCSBG); Hongya county , forest farm, July 1992, Z.W. Wang A00088 (CDBI); Hongya county , Lewu town , Shuanghekou , 2100-2230 m, 2 August 1959, Z.T. Guan 9120 (PE); Hongya County, Lewu town , Shuanghekou, 2100-2230 m, 3 August 1959, Z.T. Guan 6814 (PE); Leibo county , Mahu town , 1300 m, 25 May 1959, 238 collection team 0338 (PE); Leibo county , Shahezhou forest farm, 2400 m, 12 August 1972, 238 collection team 0697 (PE); Ya’an city, Yingjing county , Longchigou National Forest Park, Daxiangling, 29°36'21.23"N, 102°50'28.48"E, 1364 m, 19 September 2020, X. Chen, X.Y. Wang, C.H. Wang 1891 (NF); Ya’an city, Yingjing county , Longcanggou National Forest Park, Diecuixi, 29°36'55.01"N, 102°53'42.57"E, 1509 m, 19 September 2020, X. Chen, X.Y. Wang, C.H. Wang 1906 (NF); Ya’an city, Yingjing county , Longcanggou National Forest Park, Diecuixi, 29°36'57.42"N, 102°53'38.74"E, 1512 m, 19 September 2020, X. Chen, X.Y. Wang, C.H. Wang 1907 (NF); Ya’an city, Yingjing county , Longcanggou town , Fazhan village , 29°37'04.96"N, 102°53'25.17"E, 1466 m, 20 September 2020, X. Chen, X.Y. Wang, C.H. Wang 1908 (NF); Ya’an city, Yingjing county , Longcanggou town , Fazhan village , 29°38'15.34"N, 102°53'00.64"E, 1359 m, 20 September 2020, X. Chen, X.Y. Wang, C.H. Wang 1914 (NF); Ya’an city, Yingjing county , Longcanggou town , Fazhan village , 29°37'48.37"N, 102°53'13.75"E, 1358 m, 20 September 2020, X. Chen, X.Y. Wang, C.H. Wang 1915 (NF) .

Figures

Figure 1. Sorbus megalocarpa Rehder A lectotype (K 000758158) B an epiphytic plant in the wild (Ya'an, Sichuan, China) C fruit (showing the color of fruit and lenticels on it) D leaves (showing the variation of leaf shape and petiole length in one plant).

Figure 2. A holotype of Sorbus guanxianensis Ku (PE 00020830) B holotype of Sorbus arguta T. T. Yu (PE 00934274).