Vincetoxicum nakaianum K. Mochizuki & Ohi-Toma, 2024

Mochizuki, Ko, Nemoto, Shuichi, Murata, Jin & Ohi-Toma, Tetsuo, 2024, Vincetoxicum nakaianum (Asclepiadoideae, Apocynaceae), a new species from Japan for Cynanchum magnificum Nakai, nomen nudum, PhytoKeys 247, pp. 191-201 : 191-201

Vincetoxicum nakaianum K. Mochizuki & Ohi-Toma sp. nov.

Figs 1 , 2 , 3

= Cynanchum nikoense (Maxim.) Makino pro parte, Somoku-Dzusetsu, ed. 3. 1: 299 (1907), in nota excl. basionym; Makino, Bot. Mag. (Tokyo) 22: 169 (1908), excl. basionym et synonym; Makino & Nemoto, Fl. Jap.: 329 (1925), quoad descr. tantum; Makino, Ill. Fl. Jap.: 241, f. 460 (1925); Makino, Ill. Fl. Nippon: 207, f. 619 (1940).

Type.

Japan, Pref. Tochigi • Nikko city, Nikko Botanical Garden , naturally distributed, 36 ° 44 ' 59.9 " N, 139 ° 35 ' 15.1 " E, alt. 640 m, 22 May 2021, fl., K. Mochizuki KMH 0484 (holotype: TI [ 00239769 ]) .

Diagnosis.

Vincetoxicum nakaianum is morphologically similar to V. macrophyllum but is distinguished by an erect stem terminated by an inflorescence, and larger, greenish to brownish flowers, 10–15 mm in diam. (vs. flowers dark purple and 4–5 mm in diam.) with a glabrous corolla (vs. villous).

Description.

Perennial herb 30–60 cm in height. Roots fibrous fascicled. Rhizome short, erect. Stems erect, weakly pubescent, not branched, 4–6 mm in diam., terminated by an inflorescence. Leaves opposite, 1–4 pairs crowded near the shoot apex; petiole 1–4 cm long; blade broadly ovate to rhombic, 3–8 cm long, 2–6 cm wide when flowering, 8–20 cm long, 5–13 cm wide when fruiting. Inflorescence terminal and sometimes axillary, densely umbellately cymose; flowers 10–30, 5 - merous, 10–15 mm in diam., weakly pubescent, greenish; peduncle 5–20 mm long, unbranched; pedicels glabrous, 5–15 mm long, ca. 0.5 mm in diam., greenish; calyx rotate, weakly pubescent on abaxial surface, 4–6 mm in diam., deeply lobed, lobes lanceolate, ca. 2 mm long, ca. 0.7 mm wide, apex obtuse to acute; corolla rotate, 10–15 mm in diam., dull brownish to dull greenish, deeply lobed, lobes oblong, apex obtuse to orbicular, 6–9 mm long, 2–3 mm wide, both surfaces glabrous, apex obtuse to orbicular; gynostegial corona fleshy, 1.5–2 mm long, 1.5–2 mm in diam., lobes 0.75–1 mm long, ca. 1 mm wide, apex obtuse to orbicular and medially angustate. Gynostegium 1–1.5 mm in diam., slightly below level of corona; style-head flattened, 0.5–1 mm in diam. Stamen 0.6–0.8 mm long, 0.4–0.5 mm wide; anther wings 0.2–0.25 mm long; connective appendage membranous, ovate, 0.1–0.17 mm long, 0.3–0.4 mm wide. Pollinarium: corpusculum narrowly oblong, ca. 0.12 mm long; caudicles oblong, ca. 0.04 mm long, sub-basally connected to corpusculum at a 120 ° angle; pollinium ellipsoid, ca. 0.08 mm long, ca. 0.05 mm wide, subapically attached to caudicle. Follicles usually two per flower, erect, divaricate at a 70 ° – 100 ° angle, 7–15 cm long, narrow-lanceolate, gradually attenuate to apex. Seeds brown, slightly winged, narrowly ovate, 10–15 mm long, 2–3.5 mm wide; coma 2–5 cm long, silver.

Japanese common name.

Tachi-gashiwa. Makino (1890) was the first to mention the common name “ tachi-gashiwa ” as a misidentification for Vincetoxicum macrophyllum Siebold & Zucc.

Phenology.

Flowering from late March to May; fruiting from June to February.

Distribution and habitat.

Japan. Alt. ca. 100– 850 m. Central to northern Honshu: Prefs. Aomori, Iwate, Miyagi, Fukushima, Gunma, Tochigi, Ibaraki, Tokyo, Kanagawa, Shizuoka, Yamanashi, Nagano, and Aichi (see Additional specimens examined) (Fig. 4 ). Grows in understories of Japanese ceder plantation forests and deciduous forests dominated by Fagus japonica Maxim. , Abies firma Siebold & Zucc. , Quercus L., Acer L., and Carpinus L.

Etymology.

The species epithet honors Prof. Takenoshin Nakai (1882–1952), who conferred the name Cynanchum magnificum for “ tachi-gashiwa ”.

Conservation status.

Least Concern (LC). Vincetoxicum nakaianum is known from many populations throughout the central to northern Honshu island of Japan. Based on the specimen records, the extent of occurrence (EOO) is calculated to be ca. 79.000 km 2 and the area of occupancy (AOO) is 240 km 2. However, we should note that this result may be underestimated since the sampling does not cover all the known populations. This species is not listed in the Red Data Book of Japan published by the Ministry of the Environment ( Ministry of the Environment 2020). Given that the natural habitat area has not been fragmented or reduced, it is assessed here as Least Concern according to the IUCN criterion ( IUCN 2012, 2019).

Nomenclatural notes.

The following not validly published “ names ” correspond with Vincetoxicum nakaianum K. Mochizuki & Ohi-Toma.

Cynanchum magnificum Nakai, J. Jap. Bot. 8 (2): 69 (1937), in textu, nomen nudum. No Latin description, diagnosis, or even an indirect reference to any former description was provided. Therefore, the name Cynanchum magnificum Nakai is a nomen nudum (ICN Art. 38.1 and 39.1, Turland et al. 2018)

= Vincetoxicum magnificum (Nakai) Kitag., J. Jap. Bot. 34 (12): 364 (1959), nomen invalidum.

Notes.

Vincetoxicum nakaianum is unique in its early flowering habit from late March to May, while the leaves are unfolding, often with the inflorescence blooming before the leaves are fully developed (Fig. 1 B ). The leaves enlarge from flowering to fruiting, reaching ca. 20 cm long. This flowering habit is rare in the genus Vincetoxicum .

Its flowers open in the morning and persist for 2–3 days. The flowers emit a faint odor during daytime, and tiny insects are often observed flying around the inflorescence. Variations in flower color are frequently observed within large populations, ranging from entirely brown to green. In the Nikko area of Tochigi Prefecture on Honshu, this species often co-occurs with V. macrophyllum var. nikoense ; however, their flowering seasons do not overlap, and V. macrophyllum var. nikoense flowers from June to September.

Although Nakai (1937) cited no specimens, we discovered one specimen (T. Nakai, s. n., TI [00267868]) for which “ Cynanchum grandifolium Hemsley ” and “ Flores viridescentes ” were written on the original label by Nakai; the former was lined out and corrected to “ Cynanchum magnificum Nakai , sp. nov. ”, also by Nakai.

Additional specimens examined.

Japan, Pref. Aomori: • Hashikami-cho, Mt. Hashikami-dake , 25 Jun. 1946, fr., J. Koikawa s. n. ( TI [ 00267869 ]) . Pref. Iwate: • Ninohe-gun, Fukuoka-machi , 30 Jun. 1967, wilted fl. and young fr., H. Hara s. n. ( TI [ 00267870 ]) • Iwaizumi-cho, Egawa , 25 Aug. 1973, fr., M. Takahashi s. n. ( TI [ 00267871 ]) • Shimohei-gun, Iwaizumi-machi , 22 Jun. 2000, fr., K. Yonekura 5634 ( TUS [ 251310 ]) • Kesen-gun, Sumita-cho , 31 May 2001, fr., Y. Tazawa s. n. ( TUS [ 267156 ]) . Pref. Miyagi: • Kurihara-shi, Kurikoma, Monzi, Mt. Kurikoma-yama , 24 Jul. 1978, fr., W. Takahashi 19728 ( TUS [ 465015 ]) • Kurokawa-gun, Ohmori-yama , 16 May, 1915, fl., Ogura s. n. ( TI [ 00267874 ]) • Akiu, Uenohara , 6 May 1962, fl., H. Ohashi 2872, ( TI [ 00267872 ]) • Oshika-gun, Kinkazan , 23 Jun. 1963, sterile, M. Takahashi s. n. ( TI [ 00267873 ]) • Oshika-gun, Onagawa-cho, Mt. Dairokuten-yama , 5 Aug. 1973, fr., Y. Sasaki 1409-1 ( TUS [ 321031 ]) • Iwanuma-shi, Miiroyoshi , 5 Oct. 1993, fr., T. Mori 8659 - c ( TUS [ 418789 ]) • Katta-gun, Zao-machi , 18 Jul. 1986, fr., T. Mori 1607 ( TUS [ 418790 ]) • Kakuda-shi, Oda , 21 May 1992, fl., T. Mori 8222 - b ( TUS [ 418791 ]) . Pref. Fukushima: • Fukushima-shi, Matsukawamachi-mizuhara , 14 May 2002, fl., T. Kurosawa 20505 ( FKSE [ 14339 ]) • Adachi-gun, Ohtama-mura , 8 May 2001, fl., M. Sato s. n. ( FKSE [ 94390 ]) • Sohma-gun, Odaka-machi , 4 May 1969, fl., N. Sakurai s. n. ( FKSE [ 33860 ]) • Futaba-gun, Kashimadaira , 28 Jul. 1962, sterile, H. Sase, s. n. ( FKSE [ 6199 ]) • Tamura-gun, Takine-machi , 30 May 1971, fl., H. Sase 170-28 ( FKSE [ 6196 ]) • Iwaki-shi, Tabitomachi , 14 May 2014, fl., S. Nemoto 1183 ( FKSE [ 82848 ]) • Ishikawa-gun, Furudono-machi, Okaze , 24 May 2020, fl., S. Nemoto et al. 5795 ( TI [ 00267875 ]) • Nishishirakawa-gun, Koseki-mura , date unknown, fl., N. Imai s. n. ( TNS [ 31085 ]) . Pref. Gunma: • Yamada-gun, Umeda-mura , 10 May 1936, fl., H. Koidzumi 106893 ( TNS [ 904856 ]) • Kiryu-shi, Narukamiyama , May 1957, fl., Y. Asai, s. n. ( TI [ 00267877 ]) • Kanra-gun, Shimonita-machi, Kuriyama , 18 Sept. 1954, fr., T. Wakana WT 5856 ( CBM [ BS 5856 ]) • Kanra-gun, Shimonita-machi, Mt. Arafune-yama , Oct. 1954, sterile., T. Yamazaki, s. n. ( TI [ 00270877 ]) • Kanra-gun, Shimonita-machi, Mt. Myogi-san , 28 May 1954, fl., K. Sato s. n. ( TI [ 00270883 ]) . Pref. Tochigi: • Nasushiobara-shi, Ooami , 4 Jun. 2005, fl., M. Tsuchiya 11243 ( CBM [ BS 303509 ]) • Nikko-shi, Yamakubo , 22 Sept. 2021, fr., K. Mochizuki KMH 0457 ( TI [ 00239771 ]) • Nasu-gun, Bato-machi, Mt. Torinoko-san , 26 Sept. 1954, fr., S. Suzuki s. n. ( TUS [ 243360 ]) • Kawachi-gun, Kamikawachi-mura , 10 May 1964, fl., C. Okawa s. n. ( TNS [ 410216 ]) • Haga-gun, Mashiko-machi, Mt. Amemaki-yama , 18 May 1952, wilted fl., S. Suzuki s. n. ( TUS [ 243359 ]) . Pref. Ibaraki: • Kitaibaraki-shi , 3 May 1958, fl., M. Suzuki s. n. ( TNS [ 137568 ]) • Kitaibaraki-shi, Sekimoto-cho, Ogawa , 19 Sept. 2001, sterile, A. Tamura s. n. ( KPM [ 0217161 ]) . Pref. Saitama: • Iruma-gun, Agano-mura , 17 Oct. 1934, sterlile, S. Okuyama s. n. ( TNS [ 663437 ]) • Chichibu, Buko-san , 24 May, 1953, fl., S. Kurosawa s. n. ( TI [ 00267876 ]) • Hannno-shi, Agano, Mt. Nenoo-gongen , 15 Jun. 1974, sterile, M. Togashi s. n. ( TI [ 00271481 ]) . Pref. Tokyo: • Mt. Kariyose , 8 May 1930, fl., T. Nakai s. n. ( TI [ 00267868 ]), “ Cynanchum magnificum Nakai , sp. nov., ” in sched . • Usui-gun, Usui-machi , 7 Sept. 1952, fr., I. Yokota 14 ( TNS [ 115037 ]) • Hachioji-shi, Mt. Jinba , 13 May 1951, fl., S. Okuyama 9782 ( TNS [ 101552 ]) • Nishitama-gun, Itsukaichi-machi , 18 Oct. 1970, sterile, M. Harimoto s. n. ( TNS [ 754776 ]) • Ome-shi , May 1955, fl., T. Satow 8146 ( TNS [ 123870 ]) • Minamitama-gun, Asakawa-machi, Mt. Takao , 3 May 1921, fl., T. Ito s. n. ( TNS [ 396248 ], TNS [ 61439 ]) . Pref. Kanagawa: • Tsukui-gun, Tsukui-machi, Mt. Yakeyama , 20 Jul. 1980, fl., S. Kigawa s. n. ( KPM [ 1000451 ]) • Aikou-gun, Kiyokawa-mura , 26 Jun. 1981, fr., H. Takahashi s. n. ( KPM [ 1000449 ]) • Minamiashigara-shi, Saijoji , 4 Sept. 1983, fl., A. Yoshikawa s. n. ( KPM [ 1000453 ]) • Isehara-shi, Mt. Ohyama , 2 May 2003, fl., M. Morikawa s. n. ( KPM [ 0123462 ]) • Hadano-shi, Hane , 7 May 2015, fl., C. Akiko CKD- 2-46 ( KPM [ 0182259 ]) • ibid., 18 Jun. 2015, fr., C. Akiko CKD- 2-166 ( KPM [ 0181449 ]) • Naka-gun, Isehara-machi , 5 May 1966, fl., F. Kazami s. n. ( TNS [ 170266 ]) . Pref. Shizuoka: • Gotenba-shi, Higashi-tanaka , 13 Oct. 2021, sterile, K. Mochizuki KMH 0460 ( TI [ 00267878 ]) • Haibara-gun, Honkawane-cho, Ooma , 19 Jul. 1977, fr., F. Konta et al. SK 301 ( TNS [ 940477 ]) • Fujinomiya-shi, Fumoto , 30 Aug. 1977, sterile, F. Konta & T. Masuzawa 2159 ( TNS [ 940473 ]) • Fujinomiya-shi, Awakura , 8 May 1998, fl., F. Konta 18501 ( TNS [ 665002 ]) • Fujinomiya-shi, Saori , 4 May 1985, fl., T. Sato 7597 ( TNS [ 940476 ]) . Pref. Yamanashi: • Minamikomagun, Minobu-cho , 15 Jul. 1951 sterile, S. Nakagomi s. n., ( BDCJ [ 2361 ]) . Pref. Nagano: • Kitasaku-gun, Karuizawa-machi , 21 Jul. 1936, fr., K. Shirai s. n. ( TNS [ 65102 ]) • Iida-shi, Minamishinano-mura, Tayorigashima , 29 May 2010, fl., K. Hiruma s. n. ( ICM [ HE 009442 ]) • Minamishinano-mura, Tayorigashima , 31 May 2020, M. Ozeki MOCL 200531-10 ( NAC [ 214171 ]) • Minamishinano-mura, Toyamakawa , 21 Jul. 1936, sterile, R. Fujiwara 381353-22, ( NAC [ 65102 ]) . Pref. Aichi: • Nishikamo-gun, Obara-mura , Apr. 1954, fl., 16 Oct. 1960, fr., K. Inami s. n. ( CBM [ BS 72659 ], CBM [ BS 194212 ]) .

Figures

Figure 1. Vincetoxicum nakaianum K. Mochizuki & Ohi-Toma A habitat and flowering stems of a single individual B young inflorescence and coetaneous leaves C mature inflorescence D flower E top view of gynostegium F shoots of previous year (black triangles) and current year (white triangles) G young follicles H seed. Scale bars: 3 cm (A); 1 cm (B, C, F – H); 2 mm (D); 0.5 mm (E).

Figure 2. Gynostegium and pollinarium (enlarged) A oblique view of gynostegium B pollinarium C abaxial side of a stamen covered with the corona D adaxial side of a stamen E side view of a stamen. Scale bars: 0.5 mm (A, C – E); 0.1 mm (B).

Figure 3. Holotype of Vincetoxicum nakaianum K. Mochizuki & Ohi-Toma. (K. Mochizuki KMH 0484, TI [00239769]).

Figure 4. Distribution map of Vincetoxicum nakaianum K. Mochizuki & Ohi-Toma. Dots indicate the geographic locations of the specimens examined, including the holotype. Prefectures with records based on herbarium specimens are indicated in orange.