Botanical Studies (2011) 52: 115-120.
Hainanecio, a new genus of the Senecioneae, Asteraceae from China
Ying LIU2 and Qin-Er YANG1*
1Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road, Tianhe District, Guangzhou 510650, China
2State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
(Received March 31, 2010; Accepted June 10, 2010)
ABSTRACT. Hainanecio Y. Liu & Q. E. Yang, a new genus of Senecioneae, Asteraceae, from Hainan Is­land, China, is described based on Sinosenecio hainanensis (Chang & Tseng) C. Jeffrey & Y. L. Chen. Distin­guishing characters include pinnately-veined, ovate to obovate leaves, hemispherical involucres, white florets, apically acuminate and often 2-denticulate rays, basic chromosome number of x = 29, typically triporate pol­len, and helianthoid type of pollen wall ultrastructure.
Keywords: Asteraceae; Hainanecio; New genus; Senecioneae; Sinosenecio; Taxonomy.
INTRODUCTION
pinnately-veined, ovate to obovate leaves (vs. palmately-veined, rounded, reniform to ovate or deltoid), hemispheri­cal involucres (vs. obconic or campanulate), white florets (vs. yellow), and apically acuminate, often 2-denticulate rays (vs. apically obtuse and 3-denticulate rays). Among these characters, the color of the flowers is worthy of special note. In the protologue, Chang and Tseng (1974) described the flowers as being 'probabiliter aurantiaceis, (probably orange), but our field observations at two sites on Hainan (including the type locality) revealed the flow­ers to be white (Figure 2). All species of Sinosenecio have yellow flowers (Jeffrey and Chen, 1984; Chen, 1999), as do all the Chinese species of Senecio, in which the species was originally described (Jeffrey and Chen, 1984; Chen, 1999).
Hainanecio Y. Liu & Q. E. Yang, based on Sinosenecio hainanensis (Chang & Tseng) C. Jeffrey & Y. L. Chen from Hainan Island, China, is described as new. Our recent systematic study of Sinosenecio B. Nord. (Senecioneae-Asteraceae) has indicated that this enigmatic species has a series of unusual morphological, cytological, and palyno-logical characters, and thus definitely does not belong in the genus Sinosenecio.
Hainanecio hainanensis, endemic to Hainan Island, China (Figure 1), was considered to be the southernmost occurring species of Sinosenecio (Jeffrey and Chen, 1984; Chen, 1999). Originally described as Senecio hainanensis by Chang and Tseng (1974), it was transferred to Sino-senecio by Jeffrey and Chen (1984) based on its scapiger-ous habit, strictly polarized anther endothecial cell wall thickenings, and tumid epappose achenes. Jeffrey and Chen (1984) regarded those characters in combination as characteristic of Sinosenecio, although they noted simul­taneously that the species was unusual in the genus in its pinnately veined, ovate to obovate leaves. The species has since been noted as anomalous within Sinosenecio (Chen, 1999; Zhang et al., 2008), but has until now been included within the genus.
Our field and herbarium observations have confirmed and increased the number of morphological differences be­tween Hainanecio hainanensis and species of Sinosenecio:
*Corresponding author: E-mail: qeyang@scib.ac.cn; Tel: +86-20-37094273; Fax: +86-20-37094273.
Figure 1. Distribution of Hainanecio hainanensis (▲).
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7B, D). Surprisingly, the pollen grains of H. hainanensis are typically triporate, lacking the three noticeably wide colpi that are always present in pollen grains in Sinosene-cio (Figure 7E), and the tectum is smooth and perforate (Figure 7F). The pollen grains of other genera in the tribe Senecioneae have all been reported to be tricolporate (Stix,
1960; Skvarla and Turner, 1966; Skvarla et al., 1977;
Recent molecular phylogenetic studies, which did not sample Hainanecio hainanensis, have shown that Sino-senecio is a polyphyletic group (Pelser et al., 2007; Wang et al., 2009). Some species of Sinosenecio were found to be nested in a well supported clade with Tephroseris and Vincent and Norris, 1989; Liu, 2002). Furthermore, SEM shows that the pollen grains of H. hainanensis are obvi-ously less densely echinate than those of other species of Sinosenecio examined. Under transmission electron microscopy (TEM), the structure of the pollen wall of all species of Sinosenecio, except H. hainanensis, are of the senecioid type (absence of internal foramina, Figure 8A-I), the commonest pollen type within the tribe Senecioneae (Nordenstam, 2007; Nordenstam et al., 2009). Unexpect-edly, the structure of the pollen wall of H. hainanensis is of the helianthoid type (presence of internal foramina, Figure 8J-L). In the Senecioneae, the helianthoid pollen type has been reported previously only in a few genera (Nordenstam, 2007; Nordenstam et al., 2009): Doroni-cum (Skvarla et al., 1977; Liu, 2000) from the subtribe Doronicinae, Farfugium (Liu, 2000), Telanthophora and Robinsonecio (Bain et al., 1997) from the subtribe Tus-silagininae, Pericallis (Skvarla et al., 1977) and Packera (Skvarla et al., 1977; Bam and Walker, 1995) from the subtribe Senecionineae. Obviously, H. hainanensis can-not be referred to any of these six genera because of the remarkable differences in other characters.
Figure 2. Hainanecio hainanensis. A, Habit; B, Young capitula; C, Capitulum (top view); D, Florets (left: disc floret; right: ray floret); E, Capitulum (bottom view), showing phyllaries; F, Rhi­zome; G, Habitat. (All from Y. Liu 2008044, IBSC, PE).
Hainanecio hainanensis has truncate style arms with marginal and apical papillae (Figure 3A), polarized and radial endothecial cell wall thickenings, with the polarized ones being predominant (Figure 3B), and a short, cylindri­cal filament collar (Figure 3C). These features have been previously observed in species of Sinosenecio (Norden-stam, 1978; Jeffrey and Chen, 1984; Liu, 1999; Zhang et al., 2008; Liu et al., 2009). Jeffrey and Chen (1984)
reported the anther endothecial cell wall thickenings of H. hainanensis as being strictly polarized, but this was not confirmed in our study. Most notably, the anther apical appendage of H. hainanensis is ovoid and bubble-like in shape, with the abaxial cells obviously enlarged (Figure 3D). In all species of Sinosenecio the anther apical ap­pendages are ovoid, but not bubble-like, with the abaxial cells not enlarged (Liu and Yang, in prep.).
During our study, the distinctive nature of Hainanecio hainanensis was strongly reinforced by observations of the chromosomes and pollen.
The mitotic chromosome number of Hainanecio hain-anensis is 2n = 58 (Figure 3E), with a basic number of x =29. The chromosomes range from ca. 1.8 to ca. 0.8 [im from the largest to the smallest. In contrast, the basic chro­mosome numbers in the species of Sinosenecio are pre­dominantly x = 24 and 30, rarely 13, and the chromosomes are larger, usually ranging from ca. 4.0 to ca. 1.2 [im (Liu and Yang, in prep.).
All the species of Sinosenecio examined, except Hainanecio hainanensis, have the same pollen external morphology under scanning electron microscopy (SEM) (Figures 4-7). The pollen grains are spheroid, tricolporate, echinate, with the tectum coarse and not perforate (Figure
Figure 3. Floral micromorphological characters (A, B, C, D) and mitotic metaphase chromosomes (E) of Hainanecio hainanensis. A, Style-arms; B, Anther endothecial cell wall thickenings; C, Filament collar; D, Anther apical appendage; E, Mitotic meta-phase chromosomes (2n = 58) (all from Y. Liu 2008044, IBSC, PE). Scale bars: A, D = 100 μm; B = 25μm; C= 50 μm; E = 5
LIU and YANG ― Hainanecio, a new genus
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Nemosenecio ('tephroseroid' clade = subtribe Tephrose-ridinae), whereas others clustered with typical genera of Tussilagininae ('tussilaginoid'), such as Cremanthodium, Farfugium, Ligularia, Parasenecio, Petasites, Syneilesis, and Tussilago. Wang et al. (2009) have discussed in detail the strong incongruence between the ITS phylogeny and
the generic delimitation in the Nemosenecio-Sinosenecio-Tephroseris assemblage, pointing out that neither Sino-senecio nor Tephroseris as currently construed forms a monophyletic group. Both are awaiting a generic recir-cumscription. The results of our phylogenetic analysis of the ITS data set of Sinosenecio, which included a broader taxon sampling, have also revealed the polyphyly of Sino-senecio and indicated that H. hainanensis is a member of subtribe Senecioninae, only distantly related to the species of Sinosenecio, some of which may belong to the typical subtribe Tussilagininae and others may belong to subtribe Tephroseridinae (Wang et al., 2009; Liu and Yang, un-publ.). The nearest likely relatives of Hainanecio within subtribe Senecioninae could not be determined with cer­tainty in our analysis, which indicates that H. hainanensis shows no close affinities with any genera sampled. Hain-anecio may better be regarded as a fairly isolated member of the subtribe until further systematic data are available to elucidate its affinities.
Several lines of evidence (morphological, palyno-logical, cytological, and molecular), therefore, strongly support the segregation of Hainanecio hainanensis as a distinct genus. Hainanecio is easily distinguished from Sinosenecio through a series of characters as given in
Table 1.
Hainanecio Y Liu & Q. E. Yang, gen. nov.―TYPE: Sene-cio hainanensis Chang & Tseng in Fl. Hainan. 3: 585. 1974.海南菊屬
Figure 4. Scanning electron micrographs of pollen grains in species of Sinosenecio with a basic chromosome numbers of x = 24 (rarely 13). A, S. baojingensis (Q. E. Yang et al. 554, IBSC,
PE); B, S. euosmus (Q. E. Yang et al. 992, IBSC, PE); C, S. glo-bigerus (Q. E. Yang et al. 575, IBSC, PE); D, S. guangxiensis (Guangxi Exped. 4257, PE); E, S. hupingshanensis (Q. E. Yang et al. 613, IBSC, PE); F, S. jishouensis (Q. E. Yang et al. 544, IBSC, PE); G, S. jiuhuashanicus (Y. Liu & T. Deng 2008019, IBSC, PE); H, S. koreanus (Komarov 1601, PE); I, S. oldha-mianus (Yang et al. 683, IBSC, PE); J, S. palmatilobus (Q. E. Yang et al. 673, IBSC, PE); K, S. palmatisectus (Y. Liu 2008006, IBSC, PE); L, S. saxatilis (Y. Liu 2008025, IBSC, PE). Scale bar =5 μm.
Figure 6. Scanning electron micrographs of pollen grains in species of Sinosenecio with a basic chromosome number of x = 30 and in Hainanecio hainanensis. A, S. cyclaminifolius (Q. E. Yang et al. 761, IBSC, PE); B, S. dryas (Q. E. Yang et al. 851, IBSC, PE); C, S. eriopodus (Q. E. Yang et al. 641, IBSC, PE); D, S. hederifolius (Y. Liu 2008007, IBSC, PE); E, S. ligularioides (Q. E. Yang et al. 948, IBSC, PE); F, S. subcoriaceus (Q. E. Yang et al. 701, IBSC, PE); G, S. subrosulatus (Q. E. Yang et al. 1014, IBSC, PE); H, S. villiferus (Q. E. Yang et al. 771, IBSC); I, H. hainamnsis (Y. Liu 2008044, IBSC, PE). Scale bar = 5 μm.
Figure 5. Scanning electron micrographs of pollen grains in species of Sinosenecio with a basic chromosome number of x = 24 and in Tephroseris changii, a species that may better be transferred to Sinosenecio. A, S. septilobus (Y. Liu & T. Deng 2008040, IBSC, PE); B, S. sungpanensis (Q. E. Yang et al. 1042, IBSC, PE); C, Tephroseris changii (Y. Liu & T. Deng 2008028,IBSC). Scale bar = 5 μm.
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1956, fl., S. H. Chun 10928 (holotype, IBSC!). Syn-onym: Sinosenecio hainanensis (Chang & Tseng)
C. Jeffrey & Y. L. Chen in Kew Bull. 39: 238. 1984.
海南菊                              Figure 2
Rhizomes stout, to 10 mm in diameter. Stem 1-several, simple. Leaves several, radical, petiolate; petiole 5-10 cm long, sparsely lanate or glabrescent; lamina 6-12 x 4-8 cm, entire or shallowly repand-dentate, sparsely or densely white tomentose on both surfaces, later more or less glabrescent or sparsely puberulous, pinnately veined; midrib on lower surface prominent. Capitula solitary, ter­minal, 2-3 cm across including rays; scape distally 4-8-bracteolate. Involucres hemispherical, ca. 8 mm long, 12 mm broad, ecalyculate; receptacle subglabrous. Phyllaries ca. 13, uniseriate, lanceolate, apex acuminate. Ray florets 10-13, corolla tube 3 mm long; rays white, elliptic-oblong, 12-15 x 3-4 mm, apex acuminate, often 2-denticulate. Disc florets many; corolla white, campanulate, 3.5 mm long, tube 2 mm long; lobes oblong-lanceolate, 2 mm long. Anthers rounded at base; apical appendage ovoid, with abaxial cells obviously enlarged; endothecial cell wall thickenings polarized and radial, with polarized thicken-
Figure 7. Scanning electron micrographs of pollen grains in Sinosenecio saxatilis (A, B), S. dryas (C, D) and Hainanecio hainanensis (E, F), showing germination apertures and tectum surface. A, Aperture with colpus; B, Tectum, coarse and not perforate; C, Aperture with colpus; D, Tectum, coarse and not perforate; E, Aperture, without colpus; F, Tectum, smooth and perforate. (A, B from Y. Liu 2008025, IBSC, PE; C, D from Q. E. Yang et al. 851, IBSC, PE; E, F from Y. Liu 2008044, IBSC, PE). Scale bars: A, C, E = 5 μm; B, D, F = 1 μm.
Herba perennis. Rhizoma incrassatum. Folia rosulata, longe petiolata; lamina ovata usque obovata, pinnati-nervis. Capitula solitaria, terminalia; involucrum hemis-phaericum, ecalyculatum; phyllaria ca. 13, uniseriata, lanceolata, apice acuminata. Flores radii ca. 13, ligulis albis, elliptico-lanceolatis, apice acuminatis, saepe biloba-tis. Flores disci numerosi, albi. Antherae basi rotundatae; appendix apicalis ovoidea, cellulis abaxialibus conspicue amplicatis; endothecii cellulae parietes horizontales solum vel omnes sparse noduliferi; filamenti collum cylindra-ceum. Pollinis grana helianthoidea, triporata, colpis nul-lis. Styli rami apice truncati. Achaenia obovoidea. Pappus nullus.
Etymology. We name this "senecioid" genus "Hainan­ecio", because it is endemic to Hainan, the second largest island of China.
Distribution. Endemic to Hainan Island, China.
Hainanecio contains only the single species.
Figure 8. Transmission electron micrographs of pollen walls in three Sinosenecio species and Hainanecio hainanensis. A, B and C, S. euosmus (Q. E. Yang et al. 883, IBSC, PE), senecioid wall structure (absence of internal foramina); D, E and F, S. ji-uhuashanicus (Y. Liu & T. Deng 2008019, IBSC, PE), senecioid wall structure; G, H and I, S. subrosulatus (Yang et al. 1014, IBSC, PE), senecioid wall structure; J, K and L, S. hainanensis (Liu 2008044, IBSC, PE), helianthoid wall structure (presence of internal foramina). Scale bars: A, D, G, J = 5 μm; B, E, H, K = 1μm; C, F, I, L = 0.5 μm.
Hainanecio hainanensis (Chang & Tseng) Y. Liu & Q. E. Yang, comb. nov. Basionym: Senecio hainanensis Chang & Tseng in Fl. Hainan. 3: 585. 1974.—TYPE: CHINA. Hainan, Qiongzhong County, Limu Ling,
LIU and YANG ― Hainanecio, a new genus
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Table 1. Comparison of Hainanecio and Sinosenecio.
Hainanecio
Sinosenecio
Habit
Perennial herb
Perennial or rarely biennial herb
Leaf
Radical
Radical or cauline
Leaf shape
Ovate to obovate
Rounded, reniform to ovate or deltoid
Leaf veining
Pinnately veined
Palmately or rarely pinnately veined
Capitulum
Radiate
Radiate
Floret color
White
Yellow
Ray florets
Apically acuminate, often 2-denticulate
Apically obtuse, 3-denticulate
Pollen germination aperture
Triporate
Tricolporate
Pollen wall ultrastructure
Helianthoid
Senecioid
Endothecial cell wall thickenings
Polarized and radial, with polarized ones
Strictly polarized, or polarized and radial
predominant
Filament collar
Cylindrical
Cylindrical
Style-arms
Truncate
Truncate or slightly convex
Anther apical appendage
Ovoid and bubble-like in shape, with the
Ovoid, but not bubble-like in shape, with the
abaxial cells obviously enlarged
abaxial cells not enlarged
Achene
Obovoid
Cylindrical or obovoid-cylindrical
Pappus
Absent
Present or absent
Basic chromosome number (x)
29
13,24,30
Distribution
Hainan Island, China
Mainland China
ings predominant. Filament collar cylindrical. Pollen tripo-rate, helianthoid. Style arms truncate. Achenes obovoid, 3 mm long, glabrous. Pappus absent.
Additional specimens examined. CHINA. Hainan, Qiongzhong County, Limu Ling, alt. 900-1,200 m, in dense forests, 5 Jul 1960, anonymous collector (Herb. No. 323201) (IBSC); Qiongzhong County, Limu Ling, alt. 1,300 m, in dense forests, 27 Jul 2008, fl., Y. Liu 2008044 (IBSC, PE); Changjiang County, Bawang Ling, alt. 1,300 m, in dense forests, G. A. Fu 6015 (IBSC); Changjiang County, Bawang Ling, Laodian, alt. 1,200 m, in dense for-ests, 27 Jul 2008, fl., Y. Liu 2008043 (IBSC, PE); Baoting County, Baima Ling, in dense forests, 14 Oct 1936, X. Q.
Liu 27992 (IBSC).
Phenology. Flowering July to August, fruiting Septem­ber to November.
Distribution and habitat. Known from three populations on Hainan Island, China; shady places in broadleaved ev­ergreen forests; 900-1,200 m above sea level.
LITERATURE CITED
Bain, J.F. and J. Walker. 1995. A comparison of the pollen wall ultrastructure of aureoid and non-aureoid Senecio species (Asteraceae) in North America. Pl. Syst. Evol. 195: 199­207.
Bain, J.F., B.S. Tyson, and D.F. Bray. 1997. Variation in pollen wall ultrastructure in New World Senecioneae (Asteraceae), with special reference to Packera. Can. J. Bot. 75: 730-735.
Chang, C.C. and Y.C. Tseng. 1974. Senecio L. In Anonymous (ed.), Flora Hainanica, Vol. 3. Science Press, Beijing, pp. 585.
Chen, Y.L. 1999. Sinosenecio B. Nord. In Anonymous (ed.), Flo­ra Reipublicae Popularis Sinicae, Vol. 77(1). Science Press, Beijing, pp. 101-141.
Jeffrey, C. and Y.L. Chen. 1984. Taxonomic studies on the tribe Senecioneae (Compositae) of Eastern Asia. Kew Bull. 39:205-446.
Liu, J.Q. 1999. Systematics of the Tribe Senecioneae Subtribe Tussilagininae (Asteraceae) of the Eastern Asia. Ph.D. thesis, Institute of Botany, Chinese Academy of Sciences, Beijing.
Liu, J.Q. 2000. Pollen wall ultrastructures of subtribe Tussilagin-inae (Asteraceae: Senecioneae) of the Eastern Asia and their systematic and taxonomic significance. J. Wuhan Bot. Res. 18: 461-465.
Liu, J.Q. 2001. Floral microcharacters of the subtribe Tussilag-
Acknowledgments. We are very grateful to Dr. Bertil Nordenstam and Dr. David Boufford for their invaluable comments on the manuscript. This work was supported by the Knowledge Innovation Project of the Chinese Acad­emy of Sciences (KZCX2-YW-415, KSCX2-YW-Z-0918) and National Natural Science Foundation of China (Grant no. 30970183).
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Botanical Studies, Vol. 52, 2011
ininae (Asteraceae: Senecioneae) of the Eastern Asia and their systematic and taxonomic significance. Bull. Bot. Res. 21: 11-27.
Liu, J.Q., Y.P. He, and H.Z. Kong. 2002. The pollen character­istics under SEM in Farfugium and Ligulariopsis and their taxonomic significance. Acta Bot. Boreal.-Occid. Sin. 22:33-36.
Liu, Y., G.X. Chen, and Q.E. Yang. 2009. Sinosenecio baojin-gensis (Asteraceae), a new species from Hunan, China. Bot. Stud. 50: 107-113.
Nordenstam, B. 1978. Taxonomic studies on the tribe Sene-cioneae (Compositae). Opera Bot. 44: 1-84.
Nordenstam, B. 2007. Senecioneae. In J.W. Kadereit and C. Jef­frey (eds.), The Families and Genera of Vascular Plants, Vol. 8, Flowering Plants. Eudicots. Asterales. Springer, Ber­lin, pp. 208-241.
Nordenstam, B., P.B. Pelser, J.W. Kadereit, and L.E. Watson. 2009. Senecioneae. In V.A. Funk, A. Susanna, T.F. Stuessy, and J. Bayer (eds.), Systematics, Evolution, and Biogeog-raphy of Compositae. International Association for Plant Taxonomy, Vienna, pp. 503-525.
Pelser, P.B., B. Nordenstam, J.W. Kadereit, and L.E. Watson. 2007. An ITS phylogeny of tribe Senecioneae (Asteraceae)
and a new delimitation of Senecio L. Taxon 56: 1077-1104.
Skvarla, J.J. and B.L Turner. 1966. Pollen wall ultrastructure and its bearing on the systematic position of Blennosperma and Crocidium (Compositae). Amer. J. Bot. 53: 555-563.
Skvarla, J.J., B.L. Turner, V.C. Patel, and A.S. Tomb. 1977. Pol­len morphology in the Compositae and in morphologically related families. In V.H. Heywood, J.B. Harborne, and B.L. Turner (eds.), The Biology and Chemistry of the Composi-tae, Vol. 1. Academic Press, London, pp. 141-248.
Stix, E. 1960. Pollenmorphologische Untersuchungen an Com-positen. Grana Palynol. 2: 41-114.
Vincent, P.L.D. and F.M.G. Norris. 1989. An SEM study of the external pollen morphology in Senecio and some related genera in the subtribe Senecioninae (Asteraceae: Sene-cioneae). S.-Afr. Tydskr. Plantk. 55: 304-309.
Wang, L.Y., P.B. Pelser, B. Nordenstam, and J.Q. Liu. 2009. Strong incongruence between the ITS phylogeny and gener­ic delimitation in the Nemosenecio-Sinosenecio-Tephroseris assemblage (Asteraceae: Senecioneae). Bot. Stud. 50: 435­442.
Zhang, D.G., Y. Liu, and Q.E. Yang. 2008. Sinosenecio jishouen-sis (Compositae), a new species from north-west Hunan, China. Bot. Stud. 49: 287-294.
中國菊科千里光族一新屬：海南菊屬
劉 瑩2 楊親二1
1中國科學院植物資源保護與可持續利用重點實驗室（華南植物園） 2中國科學院植物研究所系統與進化植物學國家重點實驗室
本文描述了中國海南產菊科千里光族一新屬：海南菊屬(Hainanecio Y. Liu & Q. E. Yang)。本
屬從蒲兒根屬中分出'僅包含1種'即海南菊(Hainanecio hainanensis (Chang & Tseng) Y. Liu & Q. E.
Yang)。海南菊屬的主要區別特徵為：葉具羽狀脈，卵形至倒卵形，總苞半球形，花白色，舌狀花頂端
漸尖，常具2小齒，染色體基數為x = 29 ，花粉具3孔，花粉壁超薄結構為向日葵型。
關鍵詞：菊科；海南菊屬；新屬；千里光族；蒲兒根屬；分類學。