A New Species, Cerasus kumanoensis from the Southern Kii Peninsula, Japan

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1 ISSN Acta Phytotax. Geobot. 69 (2): (2018) doi: /apg A New Species, Cerasus kumanoensis from the Southern Kii Peninsula, Japan Toshio Katsuki Tama Forest Science Garden, Forestry and Forest Products Research Institute, Todori , Hachioji, Tokyo , Japan. katsuki@ffpri.affrc.go.jp A new species, Cerasus kumanoensis T. Katsuki (Rosaceae), sp. nov., is described from the southern Kii Peninsula, Japan. It is similar to C. jamasakura var. jamasakura and C. leveilleana because the corymbose inflorescences and extended peduncle are identical in these three taxa. However, C. kumanoensis is distinguished by several morphological and phenological characteristics, an earlier flowering period, narrowly ovate and smaller leaf blade (4 8 cm long, cm wide) and glabrous petiole and pedicel. Key words: Cerasus kumanoensis, flowering cherry, flowering period, Japan, Kii Peninsula The cherry genus Cerasus Mill. (Rosaceae) is widely distributed in the northern hemisphere. Nine species of Cerasus are native to Japan (Kawasaki 1993, Ohba 2001, Ikeda et al. 2017), where it has been cultivated for centuries for the aesthetic qualities of its blossoms and where many ornamental cultivars have been reported. Interspecific hybridization occurs relatively easily and numerous hybrid taxa have also been published in Japan. Although Japanese interest in cultivated Cerasus is so high that many studies have revealed morphological diversity in cultivars and hybrids (Wilson 1916, Ohwi 1953, Kawasaki 1993), in wild trees such interest has been relatively low and the morphological diversity within wild populations has not received much detailed examination. If Japanese wild Cerasus populations are examined in detail, undescribed taxa may be found, as is the case of C. sargentii (Rehder) H. Ohba var. akimotoi H. Ohba & Mas. Saito (Ohba & Saito 2000). Here, I describe a new species of wild cherry, C. kumanoensis, sp. nov., from the Kii Peninsula, Japan. Cerasus jamasakura (Siebold ex Koidz.) H. Ohba, C. leveilleana (Koehne) H. Ohba and C. speciosa (Koidz.) H. Ohba are morphologically distinct, exhibit genetic differences (Kato et al. 2014), and are treated as independent species in Japan (e.g., Ohwi 1953, Ohba 2001, Ikeda et al. 2017), although they have also been treated as varieties or forms of C. serrulata (Lindl.) G. Don ex Loudon (Koehne 1912, Wilson 1916, Chang et al. 2007). These three species are characterized by corymbose inflorescences with a long peduncle. Cerasus kumanoensis is considered to be close to the three species, because of its corymbose inflorescences and a peduncle that often extends to more than 10 mm in length during flowering. Among the species of Cerasus native to Japan, these characteristics occur only within these species. Cerasus kumanoensis has pink petals and a short peduncle (1 4 mm long) during early blooming. It is similar to C. sargentii var. sargentii in appearance (Fig. 1B E). The leaf blade on short shoots of C. kumanoensis (4 8 cm long, cm wide) is obviously shorter and narrower than in C. jamasakura (5 9 cm long, 3 4 cm wide according to Kawasaki 1993), C. leveilleana (6 12 cm long, 3 6 cm wide according to Kawasaki 1993) and C. sargentii (7 11 cm long, cm wide according to Kawasaki 1993), as

2 120 Acta Phytotax. Geobot. Vol. 69 Table 1. Comparison of characters of flowers and leaves among Cerasus kumanoensis, sp. nov., C. jamasakura var. jamasakura and C. leveilleana. Characters C. kumanoensis C. jamasakura C. leveilleana Peduncle length (mm) 1 4 ( 10) Petal color pink (to white) white white to pink Flowering period * Mid Mar. to early Apr. Early to mid Apr. Mid to late Apr. Bract figure obovate narrowly ovate broadly obovate Flower number per inflorescence 1 2 ( 3) Leaf blade ** shape narrowly ovate narrowly elliptic broadly obovate Leaf blade ** length (cm) *** 6 12 *** Leaf blade ** width (cm) *** 3 6 *** Leaf margin roughly serrate acutely serrate roughly serrate Lower surface of leaf pale green glaucous pale green Petiole and pedicel glabrous glabrous hairy * Flowering period observed in towns of Kozagawa and Kushimoto, Wakayama Prefecture, Japan, in See text. ** Leaf blade observed on short shoot. *** Kawasaki (1993). shown in Fig. 1G. The length and width of the leaf blade on the long shoots in Cerasus differ distinctly from those on short shoots (Oohara 2009), and most references provide both data of long shoots and short shoots. I refer to the sizes given in Kawasaki (1993) that is based only on short shoots. Additionally, C. kumanoensis is distinguished by its roughly serrate leaf margin (Fig. 2G) and pale green lower leaf surface (Fig. 1G), characters that in C. jamasakura are acutely serrate and glaucous, respectively. Cerasus kumanoensis is similar to C. leveilleana, but is distinguished by its glabrous petiole and pedicel (Fig. 1B, 2A, H). Another remarkable feature of Cerasus kumanoensis is its flowering period. Within its natural range C. kumanoensis blooms earlier than C. jamasakura. The flowering period in 2017 of five individuals of C. kumanoensis and C. jamasakura, and one cultivated plant of C. yedoensis (Matsum.) Masam. et Suzuki 'Somei-yoshino' in the towns of Kozagawa and Kushimoto, Wakayama Prefecture, are shown in Fig. 3. These individuals were near each other (horizontal distance within 1,700 m, altitude m), and the environment related to flowering period, such as the mean temperature between 11 February and 10 May in 2017 (6.6 C), appeared to be the same. The flowering periods of C. kumanoensis and C. jamasakura did not overlap in my observations. In individuals observed in detail, the flowering periods of surrounding individuals of the two taxa also did not overlap. As C. leveilleana blooms later than C. jamasakura (Miller-Rushing et al. 2007), C. kumanoensis and C. leveilleana also differ in flowering period and possibly do not cross with each other. Cerasus jamasakura, however, blooms later in this area than in some adjacent places. For example, in late April, when C. jamasakura blooms in Kozagawa, C. jamasakura in nearby Kamitonda has already finished flowering. Further studies are needed to determine the effectiveness of seasonal isolation between C. kumanoensis and C. jamasakura. As a result of field surveys and examination of specimens in the Makino Botanical Garden (MBK), Tokushima Prefectural Museum (TKPM), Osaka Museum of Natural History (OSA) and Wakayama Prefectural Museum of Natural History (WMNH), a new taxon, Cerasus kumanoensis, was confirmed to occur only within Mie, Nara and Wakayama Prefectures. New specimens that I collected are preserved in TFA (herbarium of Tama Forest Science Garden, Forestry and Forest Products Research Institute, Japan). Since it has been thought that only C. jamasakura var. jamasakura and C. leveilleana occur in the southern Kii Peninsula (Murata 2004, Morimoto 2011), in-

3 June 2018 Katsuki Cerasus kumanoensis, A New Species from Japan 121 dividuals of Cerasus kumanoensis have often been identified as one of them (e.g. WMNH and as C. jamasakura var. jamasakura, and OSA as C. leveilleana). Since more than 50 names have been published among C.serrulata and related taxa from eastern Asia (Ohba 2001), the relationship between them and C. kumanoensis must be examined. Prunus superflua Koidz. (1932) has narrow leaf blades (6 11 cm long, cm wide) and in general appearance is similar to C. kumanoensis, but the syntypes (Y. Nabeshima s.n., 15 Apr. 1932, KYO & TI; G. Koidzumi s.n., 17 May 1932, KYO) collected in Fukuoka Prefecture, Kyushu, have leaves with acutely serrate margins and narrowly ovate bracts, which support Ohba s (2001) treatment of it as individual variation within C. jamasakura. Six species, varieties or subvarieties have been published from the Kii Peninsula and its surroundings, but none of them corresponds to C. kumanoensis. Holotype specimens of Prunus mutabilis Miyoshi var. dilatata Nakai (1950) (K. Torii s.n., 30 Oct. 1949, TNS 81083) and Prunus toriwii Nakai (1953) (K. Torii s.n., 15 Apr. 1951, TNS 86156) from Aichi Prefecture have leaves with acutely serrate margins and narrowly ovate bracts. This supports Ohba s (2001) treatment of them as representing individual variation within C. jamasakura. Makino (1906) and Makino (1928) described Prunus pseudo-cerasus Lindl. var. spontanea Maxim. subvar. humilis Makino and Prunus ogawana Makino from Kochi Prefecture. The narrowly elliptic leaves with acutely serrate margins of the syntypes of the former (T. Makino s.n., 1889, MAK , T. Makino s.n., Jun. 1893, ) and the holotype of the latter (T. Makino s.n., 17 Jun. 1927, MAK ) suggest that both taxa from Kochi Prefecture are C. jamasakura as treated by Ohba (2001). A syntype of Prunus pseudo-cerasus Lindl. var. jamasakura Makino subvar. pubescens Makino (1908) (S. Matsuda s.n., Apr. 1902, MAK ) from Nara Prefecture has broadly obovate bracts and hairy pedicels, which support Ohba s (2001) treatment of it as a synonym of C. leveilleana. Although I have not seen authentic specimens of Prunus antiqua Miyoshi (1922) from Nara Prefecture, it was treated as a cultivar of C. leveilleana by Kawasaki (1993). Taxonomic treatment Cerasus kumanoensis T. Katsuki, sp. nov. Figs. 1 & 2. Similar to C. leveilleana (Koehne) H. Ohba, but distinguished by narrowly ovate and smaller leaf blades ( cm in C. kumanoensis vs cm in C. leveilleana), earlier flowering period and glabrous petioles and pedicels (Table 1). Typus. JAPAN, Honshu, Wakayama Pref., Kozagawa, Ikenoyama, alt. 40 m, 21 Mar. 2017, T. Katsuki s.n. (holo- : TI Iso-: TFA HDA , TNS ) Trees, deciduous, to 16 m tall (flowering well even when less than 8 m tall), DBH up to 0.3 m. Bark purplish brown, almost smooth; lenticels distinct, horizontal; young branches yellowish brown, lustrous, glabrous, extending slightly horizontally. Leaves alternate, reddish brown or green when young, appearing after flowering, petiolate; petiole mm long, usually glabrous; blade narrowly ovate, 4 8 cm long, cm wide, base rounded to obtuse, margin simply or doubly roughly serrate, serrations with an apical gland, apex caudate-acuminate, upper surface with sparse soft hairs, lower surface glabrous and pale green, slightly lustrous, lateral veins 5 8 pairs, with trichomes in vein axils; apical part of petiole or base of blade with a pair of wart-like glands; stipules lanceolate, incised serrate. Bud scales sticky, outer surface glabrous, inside with hairs. Inflorescences corymbose, mm across, 1- or 2- (or 3)-flowered, axillary, usually on previous year s short shoots and sometimes on long shoots; peduncle 1 4 mm long to sometimes over 10 mm at the end of flowering, glabrous; pedicel 6 24 mm long, usually glabrous; bracts obovate, ca. 5 mm long, incised serrate with a gland. Flowers hermaphroditic; hypanthium glabrous, reddish purple, tube campanulate, slightly broadened apically, 4 8 mm long; calyx lobes ovate or narrowly ovate, ca. 5 mm

4 122 Acta Phytotax. Geobot. Vol. 69 A B C D E F G 0 50 mm Fig. 1. Cerasus kumanoensis, sp. nov. A, shape of tree in full bloom (in Kumano on 9 Apr. 2017, TFA HAD ); B, hypanthium and calyx lobes [in Kozagawa on 21 Mar. 2017, TI (holotype)]; C E, flower (C in Kumano on 9 Apr. 2017, TFA HAD , D in Kushimoto on 21 Mar. 2017, FA HAD , E in Kumano on 14 Mar. 2017, TFA HAD ); F, mature fruit (in Kumano on 28 May 2017, TFA HAD ); G, leaves on short shoot (TI ).

5 June 2018 Katsuki Cerasus kumanoensis, A New Species from Japan 123 B 3mm E C F H A 3mm I G D 3mm 3mm Fig. 2. Cerasus kumanoensis, sp. nov. A, flower (petals removed); B, longitudinal section of flower (petals removed); C, calyx lobe; D, petal; E, bract; F, bud scale; G, margin of mature leaf (upper surface); H, leaf base and petiole; I, stone. Drawn from isotype (TNS ) and paratype (TNS ) by K. Hamasaki.

6 124 Acta Phytotax. Geobot. Vol. 69 C. k. a b c d e C. y. C. j. f g h i j 1 March April May 11 Fig. 3. Flowering period (dashed line) and full flowering period (bold line) of Cerasus kumanoensis, sp. nov. (a e), C. jamasakura (f j) and planted C. yedoensis Somei-yoshino observed in 2017 at Kozagawa and Kushimoto Town, Wakayama Prefecture, Japan. long, margin entire or serrate, spreading at anthesis. Petals pink or sometimes white and slightly pink, narrowly to broadly elliptic, mm long, 6 16 mm wide, base widely cuneate, apex emarginate. Stamens ca. 30, slightly shorter than style; filaments glabrous; pistil glabrous, mm long. Fruits globose, glabrous, 6 8 mm across, blackish purple when mature, taste slightly bitter; stone flat, ovoid, 5 6 mm long. Phenology. Coastal individuals (alt m) bloom earliest in late February whereas individuals in mountainous regions (alt m) bloom in late April. Foliation and seed germination take place slightly after flowering. Fruiting from mid May to early June. Distribution and habitat. Cerasus kumanoensis is widely distributed in the southern part of the Kii Peninsula (Fig. 4). Specific localities are Hidakagawa Town, Tanabe City, Shirahama Town, Susami Town, Kushimoto Town, Kozagawa Town, Nachi-katsuura Town, Taiji Town, Shingu City and Kitayama Village in Wakayama Prefecture, Kami-kitayama Village, Shimo-kitayama Village and Totsukawa Village in Nara Pref., and Owase City, Kumano City, Mihama Town and Kiho Town in Mie Prefecture These localities are at 0 to 800 m elevation. Cerasus kumanoensis typically grows in young secondary forests alongside other deciduous broadleaved trees. It is occurs more on ridges and slopes, less in valleys and lowlands. It is common in mountainous areas inland and also in coastal locations to the south. Japanese name. Kumano-zakura. English name. Kumano cherry. Etymology. The species epithet kumanoensis refers to old regional name of the distribution area, Kumano. Notes. Cerasus kumanoensis is morphologically distinct from C. jamasakura and C. leveilleana. The classification of Cerasus in different parts of the world, however, is inconsistent. For example, Kuitert (1999) and Chang et al. (2007)

7 June 2018 Katsuki Cerasus kumanoensis, A New Species from Japan 125 E 135 E 136 E 137 N N E 130 E 140 N 40 N 30 N Fig. 4. Locality of holotype (circle), localities of paratype (multiplication sign) and estimated distribution area (dashed line) of Cerasus kumanoensis, sp. nov. do not treat Cerasus jamasakura as a species. To clarify this confusion, it is necessary to use molecular methods and population genetics and to examine the nomenclature. The genetic variation within the domesticated populations of C. jamasakura in Japan was revealed in recent years (Tsuda et al. 2009), but the relationship with C. jamasakura var. chikusiensis (Koidz.) H. Ohba on Kyushu and C. leveilleana and C. serrulata in China have not been examined. Although it is possible to identify the taxa of Cerasus in Japan using SSR markers (Kato et al. 2014), their phylogenetic relationships have not been determined. The possibility of a hybrid origin for C. kumanoensis must also be considered, but natural hybrid swarms in Cerasus in Japan have not been examined genetically. Further studies are therefore needed to determine the taxonomic classification of these taxa, including C. kumanoensis. Paratypes. JAPAN, Honshu, Wakayama Pref., Kozagawa, Ikenoyama, alt. 40m. 28 Apr. 2017, T. Katsuki s.n. (TI I , TFA HDA , TNS ); Hidakagawa, Sogawa, 27 Apr. 2017, T. Katsuki KMN-212 (TFA HDA ); Kushimoto, Mt. Kasane, 21 Mar. 2017, T. Katsuki KMN-140 (TFA HDA ); Nachikatsuura, Myohozan, 22 Mar. 2016, T. Katsuki KMN- 061 (TFA HDA ); Susami, Esumi, 8 Sep. 2016, T. Katsuki SSM-07 (TFA HDA ); Tanabe, Hongu, Yunomine, 29 Mar. 1994, S Yamamoto 8208 (WMNH 23483); Tanabe, Ryujin, Mitsumata-hashi, 23 May 1992, A Yamamoto s.n. (WMNH 13705); Tanabe, Ryujin, Yasui, 6 Sep. 2016, T. Katsuki RYG-10 (TFA HDA ); Tanabe, Yasukawa, 6 Sep. 2016, T. Katsuki RYG-13 (TFA HDA ); Mie Pref., Kumano, Fudatate Pass, 9 Apr. 2017, T. Katsuki KMN-198 (TFA HDA ); Kumano, Kamikawa, 14 Mar. 2017, T. Katsuki KMN-116 (TFA HDA ); Kumano, Kiwa, Itaya, 9 Apr. 2017, T. Katsuki KMN-189 (TFA HDA ); Kumano, Kiwa, Nunobiki-no-taki, 21 Jul. 2016, T. Katsuki KMN-016

8 126 Acta Phytotax. Geobot. Vol. 69 (TFA HDA ); Owase, Hachiman tunnel, 21 Apr. 2017, K. Okuda s.n. (TFA HDA ); Nara Pref., Kamikitayama, Namegodani, 29 Apr. 2017, T. Katsuki KMN-239 (TFA HDA ); Totsukawa, Asahi, 30 Apr. 2017, T. Katsuki KMN-265 (TFA HDA ); Totsukawa, Seinishigawa, 3 Aug. 2006, N. Morimoto (OSA ); Totsukawa, Shiratani, 29 Apr. 2017, T. Katsuki KMN-232 (TFA HDA ). I thank Ms. Y. Yamashita, Mr. T. Hogen, Mr. K. Tanoue and Mr. S. Jyoudo of the Wakayama Prefectural Forestry Experiment Station, Mr. K. Okuda and Mr. M. Nakamura of the Mie branch, Japan Tree Doctors Association, Mr. K. Jinbo and Mr. O. Hashino of the Nanki Forestry Association, the staff of the Kozagawa Town Office, Mr. H. Sato in Kozagawa Town, the staff of the Kumano City Office and Mr. K. Okada in the Wakayama Prefectural Office for field surveys, Ms. A. Naito (WMNH), Mr. D. Sakuma (OSA), Ms. S. Fujii and Dr. K. Fujikawa (MBK), Mr. Y. Ibaragi and Mr. M. Ogawa (TKPM), Dr. H. Ikeda and Ms. A. Shimizu (TI), Dr. A. Ebihara (TNS), Dr. H. Nagamasu (KYO) and Dr. N. Murakami (MAK) for their generous support in the herbarium, and Ms. K. Hamasaki for the beautiful illustrations. References Chang, K. S., C. S. Chang, T. Y. Park & M. S. Roh Reconsideration of the Prunus serrulata complex (Rosaceae) and related taxa in eastern Asia. Bot. J. Linn. Soc. 154: Ikeda, H., H. Iketani & T. Katsuki Rosaceae. In: Ohashi, H. Y. Kadota, J. Murata, K. Yonekura & H. Kihara. (eds.), Wild Flowers of Japan, revised new edition 3: pp Heibonsha, Tokyo. (in Japanese). Kato, S., A. Matsumoto, K. Yoshimura, T. Katsuki, K. Iwamoto, T. Kawahara, Y. Mukai, Y. Tsuda, S. Ishio, K. Nakamura, K. Moriwaki, T. Shiroishi, T. Gojobori & Y. Yoshimaru Origins of Japanese flowering cherry (Prunus subgenus Cerasus) cultivars revealed using nuclear SSR markers. Tree Genet. Genomes. 10: Kawasaki, T Flowering Cherries of Japan. Yamakei Publishers, Tokyo. (in Japanese). Koehne, E Prunus. In: Sargent, C. S. (ed.) Plantae Wilsonianae part II: University Press, Cambridge, Massachusetts. Koidzumi, G Contributiones ad Cognitionem Florae Asiae Orientalis. Acta Phytotax. Geobot. 1: Makino, T Observations on the flora of Japan. Bot. Mag. (Tokyo) 20: Makino, T Observations on the flora of Japan. Bot. Mag. (Tokyo) 22: Makino, T A contribution to the knowledge of the flora of Japan. J. Jap. Bot. 5: Miller-Rushing, A. J., T. Katsuki, R. B. Primack, Y. Ishii, S. D. Lee & H. Higuchi Impact of global warming on a group of related species and their hybrids: cherry tree (Rosaceae) flowering at Mt. Takao, Japan. Amer. J. Bot. 94: Miyoshi, M Untersuchungen uber Japanische kirschen II. Bot. Mag. (Tokyo) 36: Morimoto, N Naraken Jyumoku Bunpushi. Selfpublishing. (in Japanese). Murata, G Kinki-chiho Shokubutsushi. Osaka Natural History Center, Osaka. (in Japanese). Nakai, T Contributions to knowledge of flowering plants. Bull. Natl. Sci. Mus. Tokyo 29: Nakai, T Opera phytologica novissima. Bull. Natl. Sci. Mus. Tokyo 33: Ohba, H Cerasus. In: Iwatsuki, K., D. E. Boufford & H. Ohba (eds.), Flora of Japan vol. IIb, pp Kodansha, Tokyo. Ohba, H. & M. Saito A new variety of Cerasus sargentii (Rehder) H.Ohba found at Mt. Shiraiwa-yama, Miyazaki Prefecture, Kyushu, the southern limit of distribution of the species. J. Jap. Bot. 75: Ohwi, J Flora of Japan. Shibundo, Tokyo. Oohara, T The Handbook of Flowering Cherries in Japan. Bun-ichi Co., Ltd., Tokyo. (in Japanese). Tsuda, Y., M. Kimura, S. Kato, T. Katsuki, Y. Mukai & Y. Tsumura Genetic structure of Cerasus jamasakura, a Japanese flowering cherry, revealed by nuclear SSRs: implications for conservation. J. Pl. Res. 122: Wilson, E. H The Cherries of Japan. University Press, Cambridge, Massachusetts. Received June 18, 2017; accepted January 1, 2018