MAITY, D. (2010). Tibetoseris depressa subsp. gauri D. Maity (Asteraceae), a new subspecies from eastern Himalaya. Candollea 65: 211–216. In English, English and French abstracts.
A new subspecies of Tibetoseris depressa (Hook. f. & Thomson) Sennikov (Asteraceae, Cichorieae), Tibetoseris depressa subsp. gauri D. Maity, is described and illustrated from eastern Himalaya. This taxon is compared with the related taxa of Tibetoseris Sennikov and Pseudoyoungia D. Maity & Maiti.
Introduction
Cassini (1831) established the genus Youngia Cass. for some diversified tropical weeds mainly distributed in East Asia. After that several studies including monographic work were done to highlight the generic delimitation of the genus (Ledebour, 1843–1846; Babcock & Stebbins, 1937; Kamelin & Kovalevskaya, 1993). Simultaneously, about 25–30 species were added to the genus Youngia by different workers in scattered papers. Presently, the genus Youngia has 30 species (Lack, 2007) or about 40 species (Bremer, 1994; Mabberley, 2005). Recently, Sennikov (in Tzvelev, 2007) and Sennikov & Illarionova (2008) tried to resolve the generic delimitation of the genus Youngia and have segregated three new genera based on the sections recognized earlier by Babcock & Stebbins (1937), e.g. Tibetoseris Sennikov, Crepidifolium Sennikov, and Sonchella Sennikov. The genus Youngia, these three segregates and Ixeris (Cass.) Cass., Crepidiastrum Nakai, Ixeridium (A. Gray) Tzvelev, and Askellia W. A. Weber were united in a new subtribe Ixeridinae Sennikov. The subtribe Ixeridinae is established and separated from Crepidinae by the characters viz. subglabrous biseriate involucres (outer phyllaries ¼–⅓ as long as the inner) and mostly narrowly cylindric capitula (Sennikov & Illarionova, 2008). Kilian & al. (2009) later returned these genera to the subtribe Crepidinae and treated Ixeridinae as synonym under it.
Sennikov & Illarionova (2008) considered Tiberoseris to have 10 species of which 5 species were previously placed under Youngia sect. Desiphylum by Babcock & Stebbins (1937). Later, two species were described by Shih (1995) and Shih & Cai (in Shih, 1995) under Youngia and transferred by Sennikov (2007). Another two new species and a new combination based on Crepis tianschanica Shih were published by Tzvelev (2007). Maity & al. (2009) have added a new subspecies, Tibetoseris gracilipes subsp. duthiei Maity & al.
Tibetoseris chiefly differs from Youngia by its tufted habit, its 5–15-flowered capitula and outer phyllaries ⅓ to ¼ shorter than inner, inner phyllaries 13–16 mm long, achenes with unequal 10–15 ribs. On the other hand, in Youngia, plants have paniculate foliose stems, 5–20-flowered capitula, outer phyllaries ⅛–1/10 as long as the inner, inner phyllaries 4–13 mm long. Moreover, in Youngia the lateral ribs of cypsela are much stronger than the other ribs. Tibetoseris shares many characters with Crepis but chiefly differs by the presence of biseriate involucres (Sennikov & Illarionova, 2008).
Tibetoseris depressa (Hook. f. & Thomson) Sennikov (
Crepis depressa Hook. f. & Thomson; Youngia depressa (Hook. f. & Thomson) Babc. & Stebbins) is a remarkable species within the genus Tibetoseris having orbicular to broadly ovate or deltoid leaves with entire or remotely denticulate margins and long un-winged petioles; cataphylls often present; capitula few or many (more than 30), surrounded by a crown of leaves, with 14–21 florets; outer phyllaries much shorter (⅓) than inner; receptacle areolate-fimbrillate; corolla tube equal to ligule; anther tails free; style branches black; cypselas slightly compressed, more than (6-)7 mm long, with a strong coarse beak, (9-)10-ribbed, hispid towards apex, yellow with dense blackish-brown patches; pericarp sclerenchymatous (except epidermis) with very large vallecular canals; pappus 11–13 mm long (Babcock & Stebbins, 1937; Shih, 1997; Grierson & Springate, 2001; Maity, 2005; Maity & Maiti, 2010). Interestingly, these features are totally absent in the other species of Tibetoseris. Moreover, morphologically as well as with some reproductive features like equal length of corolla tube and ligule, this species is similar to Stebbinsia umbrella (Franch.) Lipsch. (Maity & Maiti, 2007, 2010).
This species is distributed in the alpine meadows of the eastern Himalayas from Nepal, India (Sikkim), Bhutan to Tibet (China) between 3000–5000 m (Babcock & Stebbins, 1937; Kitamura & Gould, 1882; Shih, 1997; Grierson & Springate, 2001; Maity, 2005; Maity & Maiti, 2010).
Recently, Maity & Maiti (2010) reduced the heterogeneity of the genus Tibetoseris and described it as monotypic with the only species T. depressa, and a new genus Pseudoyoungia D. Maity & Maiti was described to accommodate the rest of the species of Tibetoseris (sensu Sennikov & Illarionova).
The specimens from Sikkim described by Maity & Maiti (2001) as Lactuca pseudoumbrella var. pseudoumbrella D. Maity & Maiti are regarded as conspecific with Tiberoseris depressa but have a larger growth-form (10–15 cm in diam. vs. 6–7 cm in diam.) and numerous capitula (more than 30). Therefore, Maity & Maiti (2010) have treated this taxon as T. depressa var. pseudoumbrella (D. Maity & Maiti) D. Maity & Maiti.
In course of the study of a large number of collections identified as Crepis depressa deposited at CAL and BSHC as well as from the field seen during the last 10 years while working on the flora of Sikkim were examined and we found no deviation in the characteristic features of this taxon.
Now we detected 3 interesting gatherings (total of 12 specimens) in the herbarium CAL identified as “Crepis depressa” or “Lactuca lessertiana”, and collected by Dr. Georges King's collaborators, which are surprisingly different from the typical specimens. The leaves of these specimens are lyrate-pinnatisect and are broadly oblanceolate in outline, having broadly triangular terminal lobes with broad triangular dentations, and much shorter petioles. Moreover, the size of the cypselas and the pappus are shorter than the typical ones, though they are quite alike in morphological appearance and anatomical features. These 3 gatherings had been made in eastern Himalaya, Sikkim and Nepal, in two successive years (1887 and 1888). These specimens are described here as a new subspecies of Tibetoseris depressa.
Tibetoseris depressa subsp. gauri D. Maity, subsp. nova (Fig. 1)
Typus : India: Sikkim Himalaya, Bloktan, 12,000 ft. [3600 m], VIII.1888, King's collector s.n. (holo-: CAL [255172D]; iso-: CAL [255172A, 255172B, 255172C]).
Subspecies nova haec affinis T. depressa subsp. depressa sed foliis lyratis vel pinnatisectis, ambitu oblanceolatis; petiolis quam lamina multo brevior; cypsela 4.5–5 mm; pappus 7–9 mm differt.
Tufted, perennial herb with strong vertical tap root. Caudex thick, strong, ca. 5 mm diam., without withered old leaf bases. Stem absent. Leaves radical, rosulate, several, lyrate to pinnatisect, 5–6 cm long, usually with the remnant of the laminar extension along the petioles; pinnatisect lobes 2–6 pairs, variously shaped, rhomboid, triangular or broadly oblong; terminal lobe largest, broadly triangular or broadly ovate, 1.5 × 1–1.5 cm, with broad triangular dentate lobes of variable sizes; apex of lobes and terminal lobes obtusely acute, margin of terminal lobes undulate or uneven, entire; glabrous or sparsely hairy along veins towards base; petioles much shorter then blade, 1–2.5 cm long, dilated at base. Capitula ligulate, several, large, congested, amongst radical leaves, with 14–21 florets. Involucre biseriate; outer phyllaries much shorter, 2-3 mm long, setose outside along midrib, ciliate at apex; inner phyllaries 13–14 mm long, setose outside along midrib, ciliate and crested at apex. Receptacle areolate-fimbrillate. Florets ca. 14 mm long; corolla tube glabrous, equal to ligule. Anther tails free. Pollens echinate. Style branches black. Cypselas slightly compressed, 4.5–5 mm long, with a strong coarse beak, 10-ribbed (becomes 11- or 12-ribbed at middle due to partial separation of main ribs), hispid towards apex, yellow with dense blackish-brown patches. Pericarp sclerenchymatous (except epidermis) with very large vallecular canals. Pappus biseriate, 7–9 mm long, white or stramineous, persistant.
Flowering & fruiting. — July-August.
Distribution and ecology. — India (Sikkim), Nepal. Grows in open alpine grassy slopes between 3600–5100 m.
Etymology. — The infraspecific epithet has been chosen after the name of Prof. G. G. Maiti, a renowned taxonomist and my respected teacher from whom I have learned taxonomy.
Other specimens examined. — India: Sikkim Himalaya [Nepal?], [without any precise locality], 1887, King's collector s.n. (CAL [4 specimens A, B, C & D]).
Nepal: Chingbapla, 17,000 ft. [5100 m], VIII.1888, King's collector s.n. (CAL [255173A, 255173B, 255173C, 255173D]).
Note. — The three taxa described under Tibetoseris depressa are unique with respect to the characters like areolate-fimbrillate receptacle; corolla tube glabrous and equal to the ligule; free anther tails; black style branches; cypselas yellow with dense blackish-brown patches and with a strong coarse beak; sclerenchymatous pericarp (except epidermis) with very large vallecular canals. Therefore, these characters are treated as the diagnostic features of the genus Tibetoseris (Maity & Maiti, 2010). The newly described subspecies is also unique due to the presence of lyrate to pinnatisect leaves and relatively small cypsela and pappus. A comparative morpho-anatomical study of the species of Pseudoyoungia, Tibetoseris depressa subsp. depressa and the new subsp. gauri is appended in Table 1.
Fig. 1.
— A–D: Tibetoseris depressa (Hook. f. & Thomson) Sennikov subsp. depressa. A. Habit; B. Cypsela (dorsal face, pappus removed); C. Pappus hair; D1, D2. Leaves. E–J: Tibetoseris depressa subsp. gauri D. Maity. E. Habit; F1, F2, F3, F4. Leaves; G. Floret; H. Stamen; I. Cypsela (dorsal face, pappus removed); J. Pappus hair.
[A–C: Sinha & Shukla 20455, BSHC; D1, D2: Maity & Pradhan 26880, BSHC; E–J: King's collector s.n., CAL [255172D]; F1: King's collector s.n., CAL [255173A]; F2: King's collector s.n., CAL [255172D]; F3, F4: King's collector s.n., CAL [255172C]] [Drawings by D. Maity]
Table 1.
— Comparison of morpho-anatomical characters of the Tibetoseris depressa (Hook. f. & Thomson) Sennikov subsp. depressa, T. depressa subsp. gauri D. Maity, and related species of Pseudoyoungia D. Maity & Maiti.
Acknowledgements
I am thankful to the Additional Director, Central National Herbarium (CAL), Howrah, West Bengal, India for giving permission to consult the herbarium and library. I am grateful to Prof. G. G. Maiti, Department of Botany, University of Kalyani, West Bengal, India for guidance and encouragement. Prof. A. N. Sennikov, Botanical Museum, Museum of Natural History, University of Helsinki, is warmly thanked for providing some valuable reprints.
