During a taxonomic revision of the genus Aconitum of the Great Himalaya Range, an undescribed aconite which was collected by Mr, K. Nishioka in Bhutan and was preserved in TI was discovered. This aconite is characterized by a scapose habit, persistent basal leaves until flowering, shallow navicular helmets and young seeds with narrow wings along the edges and without flounces on the side wall. Because of such characteristics, it is clear that the aconite in question belongs to Ser. Rotundifolia Steinb. A comparison between this newly described species and some of the other constituent species of Ser. Rotundifolia is made in this paper.

The present study is based mainly upon the specimens preserved in the Herbarium, University Museum, University of Tokyo (TI). I wish to express my thanks to the Curator, who allowed me to examine the specimens under his care. I am also greatly indebted to Dr. T. Tateoka of the National Science Museum, who encouraged me in the course of the study and kindly read and criticized the manuscript. Deep appreciation is due to Dr. H. Ohba of the University of Tokyo, who corrected my Latin description.

Aconitum bhutanicum Kadota, sp. nov.

Herba perennis, 15-30 cm alta. Tubera incognita. Caulis erectus, teres, simplex vel interdum basaliter ramosus, magis tenuis, partis dorsalis 1-3 mm diametro, sparsim hirsutus, ramis elongatia et divaricatis. Folia 4-6, plemmque basalia, in rosulam laxam supra partem subterraneam caulis aggregata, coaetanea, subcoriacea-membranacea, orbicularia, pagina adaxiali atroviridia abaxiali glauca, utrinque fere glabra sed ad marginem ciliata et in parte proximali laciniae hirsuta; laminae 1-2.5 cm latae et longae, leviter 5-7-lobatae; lobi medii obovati, obtusi, 0.5-1 cm lati et longi, valde leviter trifidi; lobi laterales inaequales, late ovati, obtusi, 1-2 cm lati, circ. 1 cm longi, in duo segmenta improfunde divisi; dentes obtusi cum acmnine, 2-3 mm lati; costa et venae laterales in pagina abaxiali minute erigentes; folia caulina eis basalibus similia sed plus profunde divisia cum dentibus paulo acutis; petioli teretes, recti, 2-9 cm longi, in pagina adaxiali canaliculati, sparse hispidi vel paene glabri, partibus basalibus latis factis et amplexicaulibus. Inflorescentia terminalis laxe racemosa, 2.5-4.5 cm lata, 6-10.5 cm longa, 2-5-florifer, bracteata; bractea 1-3 cm lata, 1-2.5 cm longa, foliacea, 5-lobata ad instar foliorum caulium. Pedicelli ascendentes, 2.5-5 cm longi, omnino hispidi, bi-bracteolati; bracteolae subulata vel ovata et 3-lobata ut in foliis, 0.5-6 mm lata, 2-8 mm longa, ad vel supra medium pedicellorum sita, partibus proximalibus sparse hispidis. Flores violacei cum venis saturate purpureis, circ. 15 mm lati, 25-30 mm alti, utrinque sparsim hispidi. Casses naviculares nec lunatae, 22-23 mm lati, 10-11 mm altae, acutae, brevi-rostres, marginibus inferis parce conversis, unguibus minoribus quam 1 mm longis. Sepala lateralia orbicularia, 19-20 mm lata, 17-19 mm longa, parce sinuata, intus pilis deficientibus, unguibus 2 mm longis. Sepala infera late elliptica-late obovata, 7-10 mm lata, 12-13 mm longa, unguibus minoribus quam 1 mm longis. Nectaria glabra, unguibus longis et tenuibus; laminae clavatae, circ. 2 mm latae, circ. 3 mm longae, in parte basali auriculatae, ab unguibus incuratis pendentes; labella angustiora et longiora, circ. 1 mm lata, circ. 3 mm longa, emarginata nec reflexa; unguies minores quam 1 mm lati, 17-19 mm longi, partibus proximalibus fortiter incurvatis; calcaria circ. 0.5 mm longa, ad apicem laminae sita, capitata, recta. Stamina dense hispida, longitudine filamentis dimidio aequantia; alae gradatim attenuatae vel in ungue transformatae. Carpella 5, contingentia, omnino dense hispida. Folliculi ignoti. Semina immatura, dilute castanea, obpyramidalia, 3-angulata et secus porcas anguste alata, circ. 1 mm lata et longa, faciebus laevigatis nec lamellati.

BHUTAN. Chumolhari Chakan (K. Nishioka s.n., Sept. 6, 1966, fl., Holotype in TI, Isotype in TI); near Lingshi Daong (K. Nishioka s.n., Sept. 8, 1966, fl., TI).

Distr. Alphine zone of Bhutan (endemic).

Leaf Division and Lobe Incision

In the following note on the degree of leaf division and lobe incision, the indices LI, LD and LLD are employed according to Kadota (1981; 1984; 1987). Leaf blades are shallowly (LD: 0.27-0.43) 5-7-lobed; middle lobes are very shallowly (LI: 0.30-0.40) trifid; lateral lobes are very shallowly (LLI: 0.46- 0.77) divided into two segments.

Pubescence

Stem is sparsely pubescent with rough-surfaced curved or descending hairs (Fig. 1c). Leaves are almost glabrous on both sides but hirsute with rough- surfaced spreading hairs along margins and with rough-surfaced straight and appressed hairs in the proximal parts of laciniae (Fig. 1d). Petioles are sparsely hirsute with rough- surfaced somewhat spreading hairs (Fig. 1d) or almost glabrous. Pedicels are hirsute with rough-surfaced spreading hairs throughout the surface (Fig. 1b). Bracts are sparsely hirsute with rough-surfaced spreading hairs in the proximal parts. Sepals are sparingly hirsute with rough-surfaced spreading hairs on the abaxial sides at the distal portions (Fig. 1b) and glabrous on the adaxial sides. Consequently lateral sepals are devoid of long hairs; the long hairs are usually seen in many species of the genus Aconitum subgenus Aconitum (e.g., all the Japaneae species), and considered to be functionally pollen-collecting trichomes. Stamens densely hirsute along filaments with rough-surfaced spreading hairs (Fig. 1m). Carpels densely hirsute with rough-surfaced ascending hairs throughout the surface (Fig. 1m).

Helmet

Helmets have convex lower margin, so they are not lunate or sickle shaped. It is noteworthy that helmets are clawed although they are subsessile. Until now an annual aconite A. gymnandrum is the only species which bears conspicuous stalked helmets (Maximowicz, 1889; Stapf, 1905; Wang, 1979).

Nectary

Each nectary has a pair of small auricles as appendages in the distal portions of lobes (Fig. 1k, arrow). A structure like the auricles has not been previously mentioned except for A. heterophyllum; in the case of the specimen (Stainton, Sykes & Williams 3795, from Nepal, TI) ascribed to A. heterophyllum, nectaries have larger auricles in the distal portion of lobes in agreement with the illustration of Stapf (1905, plate 100, fig. 4). Aconitum heterophyllum is, however, quite different from A. bhutani cum not only in shape and size of nectaries as a whole but in plant habit and leaf shape. As shown in Figure 1 (j and k), in A. bhutanicum, labia are narrow and relatively long, very shallowly 2-lobed in the apical parts, and not reflexed. Spurs are situated at the top of the lobes and very short, capitate, straight and not bending forward.

Seed Sculpture

The number of wings along edges and the presence or absence of flounces on seed walls are evaluated to be important diagnostic characteristics in the classification of the genus Aconitum (e.g., Wojciechowska & Makulec, 1969; Wang et al., 1979). According to Wojciechowska & Makulec (1.c.) writing about the European species, the following two types of seed sculpture can be recognized: 1) seeds with three conspicuous wings and without membranous flounces, 2) seeds with one conspicuous wing and membranous flounces (sometimes side walls may be rugose).

In this study, young seeds which were taken out from immature ovaries were solely examined and it was determined that these young seeds have narrow and smooth wings along the edges and do not have flounces on their side walls (Fig. 1g). In some Aconitum species having seeds of the second type described above (e.g., A. senanense and A. japonicum, both endemic to Japan), both wings and flounces begin to grow almost simultaneously in the ontogenical development of seed coats. Therefore seeds of A. bhutanicum undoubtedly fall in the first type.

Aconitum bhutanicum is closely related to A. rotundifolium and A. tanguticum in plant habit, shape and division of leaves and helmet shape. In order to compare the newly described aconite with A. rotundifolium and A. tanguticum, the delimitation of both taxa is necessary. Hence a rearrangement of synonyms of both species is presented in the following:

Aconitum rotundifolium Kar. et Kir., Bull. Soc. Nat. Mosc. 15: 149 (1842)- Ledeb., Fl. Ross. 1: 740 (1842)-Regel, Bull. Soc. Nat. Mosc. 23: 86 (1850); Pl. Radd. 115 (1861)-Finet et Gagncp., Bull. Soc. Bot. Fr. 53: 213 (1905)-Stapf, Ann. Roy. Bot. Gard. Calc. 10: 149 (1905)-Steinb., in Kom. Fl. URSS 7: 229 (1937)-Paelov et al., Fl. Kazakhst 1: 53. tab. 7, 2-2a (1961)-Mukerjee, Bull. Bot. Surv. Ind. 3: 101 (1962)- Lauener, Not. Roy. Bot. Gard. Edinb.26: 10(1964); in Hara et Williams, Enum. Fl. Pl. Nepal 2: 10 (1978)-W. T. Wang, in Fl. Reipubl. Popul. Sinicae 27: 188. pl. 34, 1-2 (1979)-Bot. Inst., Acad. Sin., Icon. Corm. Sini. 1: 698. fig. 1395 (1980)-Aconitum napellus L. var. rotundifolium (Kar. et Kir.) Hook. f. et Thoms., Fl. Brit. Ind. 1: 29 (1872). Type: USSR, Central Asia, the Ala Tau Range, 'the banks of River Sarkhan', date?, collector? (LE).

Aconitum tianschanicum Ost.-Sacken et Rupr., Sert. Tianschan. 38 (1896). Syntypes: USSR, Central Asia, Tien Shan, near Mt. Djaman-Too, Jul. 22, 1867, fl, V. A. Poltaratska; the Maibantag Range, Jul. 28, 1867, fl, V. A. Poltaratska; the At-Bashy Range, near Lake Turugart, Aug. 3, 1867, fl, V. A. Poltaratska. These locality data are read from the attached itinerary map because they are not given in the protologue. These specimens may be preserved in LE.

Aconitum rotundifolium Kar. et Kir. subsp. iliense Worosch., Bot. Zhurn. SSSR 30: 132 (1945)-Czerepanov, Add. Corr. Fl. URSS, 479 (1973). Type: USSR, Central Asia, Tien Shan, 'in pratis subalpinis, Kazachstania, Alatau Transiliensis, ad fontes fluv. Almaatinka', 1938, N. A. Plotnikov (Herb. Univ. Moscow).

Aconitum rotundifolium Kar. et Kir, var. obtusilobum Tamura in Kitamura Fl. Afghan. 119 (1960). Type: Afghanistan, Hindu Kush, Nuristan, between Chatrass and Kushimaicot, Aug. 2, 1955, S. Kitamura s.n. (KYO).

Aconitum tanguticum (Maxim.) Stapf, Ann. Roy. Bot. Gard. Calc. 10:151 (1905)- Hand.-Mazz., Acta Hort. Gothob. 13: 90 (1939)-Worosch., Byull. Gravn. Botan. Sada (Moskva) 64: 33, 37 (1967)-Inst. Bot. Bor.-Occ. Acad. Sinicae, Fl. Tsinling. 1: 261, fig. 223 (1974)-W. T. Wang. in Fl. Reipubl. Popul. Sinicae 27: 182. pl. 33, 1-4 (1979); in C. Y. Wu (ed.) Fl. Xizang. 2: 22. fig. 5, 1-2 (1985)-Bot. Inst., Acad. Sin., Icon. Corm. Sini. 1: 697. fig. 1394 (1980)-Aconitum rotundifolium Kar. et Kir. var. tanguticum Maxim., Fl. Tangut. 26 (1889)-Finet et Gagnep., Bull. Soc. Bot. Fr. 53: 213 (1905). Syntypes: [Maximowicz cited the following six specimens collected by N. M. Przewalski and G. N. Potanin. These specimens may be preserved in LE]. Amdo, in an alpine meadow of a mountain range near the River Tetung, Jul. 18, 1872, fl; in the same mountain urea to the south of the same river, rare, Jul. 30, 1872; among rocks in the same area, Jul. 31, 1880, at the beginning of flowering; in dense forest at the same place, Aug. 8, 1872, fl; along the River Rako-goly, in alpine meadow, frequently, on humid soils, Jul. 19, 1880. NE Tibet, in alpine meadow of the Burchan Budda Range, abundant, Aug. 13, 1884.

Aconitum popovii Steinb. et Schisch. ex Sipliv., Nov. Sist. Vyssh. Rast. 11: 335 (1974)-Malyschev, Fl. Alp. Mont. Sajan. Orient. 129 (1965)-Type: USSR, Central Siberia, 'Montes Sajan Orientalis, jugum Tunkense, fl. Chubuta, in prato temperate irrigito', Jul. 11, 1957, fl, L. Malyschev & N. Misjura s.n. (LE holotype; IRK isotype).

Aconitum tanguticum (Maxim.) Stapf var. trichocarpum Hand.-Mazz., Acta Hort. Gothob. 13: 91 (1939)-Inst. Bot. Bor.-Occ. Acad. Sinicae, Fl. Tsinling. 1: 262 (1974)- W. T. Wang, in Fl. Reipubl. Popul. Sinicae 27: 184 (1979); in C. Y. Wu (ed.) Fl. Xizang. 2: 22. fig. 5, 1-2 (1985)-Bot. Inst., Acad. Sin., Icon. Corm. Sinic. 1: 697 (1980). Type: China, Prov. Szechuan, Dongrergo, in prato alpino, c. 4300m, H. Smith 3817(w).

Aconitum rotundifolium auct. non Kar. et Kir.: Hand.-Mazz., Symb. Sinicae 7: 286 (1931).

Aconitum bhutanicum ia closely related to A. rotundifolium, but the former ia dis- tinguished from the latter in pedicel pubescence (hirsute with rough-surfaced spreading hairs vs. strigose with rough-surfaced curved hairs), division of nectary labia and lamina shape (shallowly 2-lobed with short and orbicular lamina vs. deeply 2-lobed with long and filiform lamina), and shape and direction of nectary spur (truncate and erect vs. round and bending inward).

Aconitum bhutanicum ia different from A. tanguticum in indumentum of pedicels (hirsute with rough-surfaced spreading hairs vs. strigose with rough-surfaced curved hairs), length of helmet claw (subsessile vs. sessile), helmet beak shape (acute and short projecting vs. acuminate and long projecting), nectary spur shape (truncate vs. hemispherical), length and direction of nectary claw (intensely incurved vs. erect) and length of nectary labium (long vs. short).

References

Anonymous. 1974.

Aconitum. In: Instituto Botanico Boreali-Occidentali Academiae Sinicae, Flora Tsinlingensis, 1 (2): 252-263. (In Chinese.)

Kadota, Y. 1981.

A taxonomic study of Aconitum (Ranunculaceae) of the Akaishi Mountain Range in Central Japan. Bull. Natn. Sci. Mus., Tokyo Ser. B, 7: 91-112.

———. 1984.

Morphological variation and distribution of Aconitum subgenus Aconitum (Ranunculaceae) in the Tohoku District, Japan. Mem. Natn. Sci. Mus., Tokyo 17: 77-90.

———. 1987.

A revision of Aconitum subgenus Aconitum (Ranunculaceae) of East Asia. xvii+249+65 pp. Sanwa Shoyaku Co., Utsunomiya.

Lauener, L. A. 1964.

New species and records of Aconitum of Nepal. Not. Bot. Gard. Edinb. 26: 1-10.

———. 1979.

Aconitum. In: Hara, H. & L.H. J. Williams. An enumeration of the flowering plants of Nepal, 2:9-11.

Malyschev, L. I. 1965.

Aconitum. In: Flora alpina montium Sajanenaium orientarum. Revisio plantarum vascularium, constitutionis spectamina et florigenesis, 127-129. (In Russian.)

Maximowicz, C. J. 1889.

Aconitum in Flora Tangutica, 1: 25-27.

Osten-Sacken, F. von and Ruprecht, F. J. 1869.

Sertum Tianschanicum. Botanische Ergeb- nisse einer Reise in Mittleren Tian-Schan. Mem. Acad. Sci. St. Pétersb. 7 Ser. 14: 1-74.

Paelov, N. V. 1961.

Aconitum in Flora Kazachstana, 48-58. (In Russian.)

Stapf, O. 1905.

The aconites of India: a monograph. Ann. Roy. Bot. Gard. Calc. 10: 115- 197.

Steinberg, E. I. 1937.

Aconitum. In: Komarov, Flora URSS 7: 183-236. (In Russian.)

Tamura, M. 1960.

Aconitum. In: Kitamura, S., Flora of Afghanistan, 118-119.

Wang, W. T. 1979.

Aconitum. In: Wang, W. T., et al., Flora Reipublicae Popularis Sinicae, 27: 156-326. (In Chinese.)

———. 1985.

Aconitum. In: Wu, C. Y. (ed.), Flora Xizangica, 2: 16-39. (In Chinese.)

Wojciechowska, B. & Makulec, J. 1969.

Seed morphology and anatomy of some Aconitum species. Monogr. Bot. 29: 137-157. (In Polish with English summary.)

Woroschilov, V. N. 1967.

Sibirskie bidy roda Aconitum. Byull. Gravn. Botan. Sada 64: 33-40. (In Russian.)