Taraxacum pudicum Vašut & Majeský, 2015

Vašut, Radim J. & Majeský, Ľuboš, 2015, Taraxacum pudicum, a new apomictic microspecies of T. section Erythrosperma (Asteraceae) from Central Europe, Phytotaxa 227 (3), pp. 243-252 : 244-249

Taraxacum pudicum Vašut & Majeský , sp. nov. ( Figs. 1–2 )

— Taraxacum aff. slovacum Klášt. in Vašut et al. (2004: 647).

Description:—Plants delicate with rich leaf-rosettes. Leaves pale (greyish)-green, without spots, usually 4–5× longer than wide, approximately 3–10(–15) cm long and 0.5–2.0 cm wide. The leaf blade is narrowly oblanceolate to elliptic, usually broadest in the middle or upper 1 / 3, having 3(–4) pairs of lateral lobes. Lateral lobes of the inner leaves narrow and falcate, with a distal margin denticulate and convex and a proximal margin usually concave and entire. Lateral lobes of the outer leaves usually triangular or broadly falcate with entire margins, which are convex on the distal margin and concave on the proximal margin. Terminal lobes of the outer leaves distinctly triangular and acute and usually undulate on the distal margin; the proximal margin often has a pair of distinct teeth close to the central vein. Terminal lobes of the inner leaves tripartite, shortly lingulate, and sometimes denticulate on the distal margins, with an extended narrow acute tip. Interlobia large with a scarce narrow tooth. The petiole unwinged, green to pale purple and lanate at the base. Scapes short, usually shorter than or as long as the leaves, green at flowering and purplish at ripening, slightly lanate. Capitulum convex, 2.5 cm in diameter, (pale) yellow, outer strips grey-brown with pinkish fade. Inner bracts greyish-green and corniculate. Outer bracts usually 10–12, lanceolate to narrowly ovate, usually 5–7 mm long, 1. 5–2.0 mm broad and greyish green, with a white hyaline margin narrow but distinct (0.1–0.2 mm broad), erect or only slightly recurved and corniculate. Stigmas yellow-green, dark-green when dried, with pollen present (irregularly sized). Achenes brown-purple, almost brown when dried, distinctly chestnut-red when not fully ripe, distinctly narrow, only sparsely spinulose, 3.6–4.0 mm long and 0.5–0.8(–0.9) mm broad, with a pyramid narrowly conical to cylindrical, (0.6–)0.8–1.0 mm long, a rostrum 5.0–6.0 mm long, and the pappus white.

Type:— CZECH REPUBLIC. South-western Moravia, district of Znojmo, along paths and roads in woods on sands between the villages of Kravsko and Bojanovice , approximately 2 km north of the centre of the village Kravsko , 370 m a. s. l., 48°56’30”N, 15°59’12”E, 1 May 2000, R. J. Vašut T-201.4 (holotype OL [herbarium specimen #24511], Fig. 1 ; isotypes OL [herbarium specimens #24512–21517], Fig. 2 ). [ FCM, FCSS, CN, GD, cult.] .

Etymology:— pudicum = chaste, modest, pure, virtuous. The name reflects short stems and a usually pale green appearance and an overall delicate habit of the plants. The plants, especially in cultivation, have flower heads “hidden” in pale green leaves.

Karyology:— 2n = 3x = 24 (counted from the holotype locality); 2n ~ 3x, distinguished by flow-cytometry ( Vašut et al. 2004).

Mode of reproduction:—This species is apomictic. The mode of reproduction was tested in a single population (Kravsko-Bojanovice) and it was confirmed to be diplosporous apomixis by FCSS. Additionally, seeds of plants from five different populations were confirmed to also be obligate apomicts. These are marked in the list of known localities by [FCSS].

Similar species:—The newly described species Taraxacum pudicum is quite distinct in its morphology. When it is well developed, it usually cannot be confused with any other described species in Central Europe. However, an undescribed morphotype sharing some characteristics with T. pudicum occurs rarely in the region. This unnamed morphotype has a more toothed leaf blade, broadened appendices on lateral lobes—similar to those of T. danubium Richards (1970: 108) —and broader (up to 0.5 mm) white hyaline margins on outer bracts. The general appearance of a delicate habit, the pale green colour of the whole plant, patent to adpressed outer bracts and narrow achenes in that unnamed plant suggests its putative relationship to T. pudicum , which was also confirmed by genetic analyses ( Majeský et al. 2015).

Plants from extremely dry habitats and growing on rocky slopes are usually very small and have very narrow lobes. The terminal lobe is sometimes denticulate in such plants, which might lead to misidentifications as e.g. T. cristatum Kirschner et al. in Vašut et al. (2005: 204). However, this species differs in several distinct characteristics that are not influenced by ecological conditions. In particular, the achenes of T. cristatum have a broader shape and a slightly more spinulose upper part of the achene, and are brown in colour. The outer bracts of T. cristatum are spread distinctly and disorderly (to recurved), and it does not have the visually distinct hyaline margin of T. pudicum .

Taraxacum discretum Øllgaard (1986: 21) is another species found in NW Europe and is superficially similar to T. pudicum . However, based on field observations by the first author (Schiermonnikoog, the Netherlands), on the original descriptions ( Øllgaard 1986) and on Hans Øllgaard’s observations (H. Øllgaard, 2001 in litt.), it clearly differs from T. pudicum in having narrow leaves, recurved outer bracts that are dark greyish-green and a longer achene-cone that can be up to 1.2 mm in length.

Taraxacum slovacum Klášterský (1938: 8) is a species described from a single herbarium specimen of juvenile plants of T. sect. Erythrosperma . Juvenile plants of T. pudicum somewhat resemble plants of the holotype specimen of T. slovacum . The first author visited the type locality of T. slovacum and searched intensively for any morphotype that would resemble juvenile plants from the holotype specimen. No T. pudicum plants were found in the type locality (Zádiel, Slovakian Karst, SE Slovakia) or in the larger region, but diploid sexual plants having similar morphology to the holotype plant were found frequently. Based on these field observations, T. slovacum is very likely just a remarkable morphotype within the range of variability of the sexual species T. erythrospermum and is not related to T. pudicum . The first author published genetic data ( Vašut et al. 2004) for T. pudicum under the name “ T. aff. slovacum Klášt. ” because data on T. slovacum from the field were not available at that time.

Ecology:— Taraxacum pudicum occurs mostly in semi-ruderal dry habitats, especially in sandy soils (mostly paths in open locust-woods of the Balloto nigrae-Robinion). However, it also grows in similar semi-ruderal habitats in pine woods, xerothermic grasslands (Festucion vallesiacae, Koelerio-Phleion phleoidis) and occasionally in ruderal places, such as abandoned mining areas and road verges.

Distribution:— Taraxacum pudicum is a Central European species. It occurs in the southern part of the Czech Republic (both Bohemia and Moravia), Lower Austria and Slovakia. The species is rather rare and has scattered occurrence within the distribution area. A higher concentration of localities was observed in the region between Brno and Znojmo city in Moravia (at the foothills of the Bohemian Massif).

Additional specimens examined:— CZECH REPUBLIC. Bohemia: Obory (Příbram): along the field path near the locality Hromádky (441.6 m), 2–2.5 km W (R. Hlaváček 31.5.1995 herb. R. Hlaváček, #C–7633). — Chrást u Kovářova, margin of forest on right bank of the Orlická přehrada dam, opposite the Orlík castle. 365 m a. s. l. (M. Soukup, V. Chán & V. Žíla 2003 herb. Žíla) [very typical plants!]. — Písek, xerothermic slopes near village Dědice, ca. 380–420 m a. s. l. (J. Moravec 1959 PR). [ T. cf. pudicum ]. — Stříbro, in valle Úterecký p. infra casam Šipín 1950 M. Deyl PR). — Nasavrky, Na Strádově (Železné hory), ca. 400 m a. s. l. (R. Hendrych 1942 PR) [ T. cf. pudicum ].

— CZECH REPUBLIC. Moravia: Budišov village, paths in pine forest on Kněžský kopec hill, 1.5 km towards E from the centre of village, 490 m a. s. l., 49°16’22”N 16°02’02”E (R. J. Vašut & Ľ. Majeský 2008 OL) [FC, GD, cult.]. — Havraníky: heathland 1.2 km towards W from the village (P. Bureš et V. Grulich 1991 BRNU). — Ketkovice: castle ruins Levnov, 3.0 km towards SW from the centre of village, 330 m a. s. l. (R. J. Vašut 1999 OL). —Kravsko: road verges and paths, 1.5 km towards N from the centre of the village, 350 m n. m (R. J. Vašut 2000 OL). —Střížov near Jihlava, dry xerothermic slopes in S outskirts of the village the village, 475–530 m a.s.l. (J. Růžička s.d. MJ) [ T. cf. pudicum ]. —Kuřimská Nová Ves: xerothermic slopes on N outskirts of the village, 0.5 km towards NW from the centre of village, 480 m a. s. l. (R. J. Vašut 2000 OL). —Malhostovice: Malhostovická Pecka hill, 1. 0 km towards SSW from the centre of village, 330 m a. s. l., 49°19’33”N 16°29’42”E (R. J. Vašut 1999 OL). [FC, FCSS, GD, cult.]. —Olbramkostel: castle ruins Šimperk, 3.0 km towards WWN from the centre of the village, 390 m a. s. l. (R. J. Vašut 2000 OL). —Pocoucov: xerothermic hill near the road to the Trnava village, 1.5 km towards NE from the centre of village, 460 m a. s. l. (R. J. Vašut 2000 OL). —Synalov —Kopaniny: pathways on S slope of the hill Sýkoř (702 m), 1.0 km towards S from its summit, 620 m a. s. l. (R. J. Vašut 1999 OL). [FC, GD, cult.]. —Tišnov —Květnice hill (470 m): pathway and S rocky slopes, 0.8 km towards SW from its summit, 380 m a. s. l. (R. Vašut 1999 OL). [FC, GD, cult.]. —Trnava u Třebíče, dry pasture, ca. 0.8 km towards NNW from the church in village, 460 m a. s. l., N 49°15’33,9” E 015°55’32,1” (L. Ekrt 2012 Ekrt herb.) [ T. cf. pudicum ].

— AUSTRIA. Lower Austria: Baden, paths along castle ruins Rauhenstein, ca. 300 m a. s. l., 48°00’48”N 16°12’18”E (R. J. Vašut & Ľ. Majeský 2009 OL) [ T. cf. pudicum ].

— SLOVAKIA. Košická Belá, Sivec hill (781 m a. s. l.), rocks at top of the hill (M. Dudáš 2015 herb. M. Dudáš) [ T. cf. pudicum ]. —Ladmovce, Kašvár hill, along pathways (M. Dudáš 2015 herb. M. Dudáš).

— POLAND. occurrence of species is yet unknown, however, some plants extreme in their morphology (grown either in shadow or in high grass) that resemble T. pudicum in several characters (outer bracts, achenes, the design of leaf-blade morphology) were collected in the vicinity of Żuchlów in Lower Silesia (Województwo dolnośląskie). This occurrence has to be confirmed by observing well developed plants.

Discussion:— The newly described species, T. pudicum , belongs to T. sect. Erythrosperma , which is comprised of (at least) one sexual diploid species, T. erythrospermum Andrz. , and about 150 apomictic microspecies. Within this section, it belongs to the T. scanicum group that consists of 16 previously described species ( Doll 1973, Øllgaard 1986, Schmid 2002, Vašut 2003, Vašut et al. 2005, Marciniuk et al. 2009). Widely distributed species of this group, i. e., T. prunicolor , T. cristatum and T. scanicum s. str., can hybridise with T. erythrospermum , resulting in local (couple of localities) or singular hybrid populations ( Majeský et al. 2015). Although we did not detect hybridisation between T. pudicum and T. erythrospermum , we found morphotypes similar to T. pudicum that differed genetically. Thus, hybridisation between these species seems to be highly probable at sites where these species meet. This has to be taken into consideration when identifying T. pudicum from localities with the co-occurrence of T. erythrospermum .

The facts that i) the distribution area of T. pudicum highly overlaps with the NW limit of the distribution of T. erythrospermum in Central Europe, ii) the species has a significant plasticity depending on the biotope, and iii) a “sibling morphotype” occurs on sands of Pannonia, led the first author to question whether it is a stabilised species or just a hybrid of T. erythrospermum and some member of the T. scanicum group (e. g., T. cristatum ). The genetic analyses of the microsatellites and AFLPs performed by the second author confirmed that individuals from different biotopes and different parts of its area are genetic clones and that if it is a hybrid then it is a hybrid of an older evolutionary history that spread over the SE part of Central Europe (see also Majeský et al. 2015). Taraxacum pudicum is one of 22 unnamed morphotypes mentioned by Vašut (2003) from the region of Moravia. In addition to this species, ( Májeský et al. 2015) also studied genetic diversity of another three additional unnamed types (and four species) of the T. scanicum group out of these 22 unnamed types to find the origin of these local taxa. Taraxacum pudicum and other species of the T. scanicum group turned out to be genetically uniform, although putatively hybridising with sexual species. On the contrary, the remaining two unnamed morphotypes appeared to be morphologically as well as genetically variable and considered to be the result of ongoing hybridisation between a group of apomictic species and the sexual T. erythrospermum ( Majeský et al. 2015) . We are convinced that such hybrids—although having apomictic reproduction—do not deserve the rank of species and should be named by the name of the group, i. e., either as T. scanicum agg. or T. sect. Erythrosperma only.

Figures

FIGURE 1. Holotype of Taraxacum pudicum. Bar = 5 cm.

FIGURE 2. Isotypes of Taraxacum pudicum. Plants with well-developed inner leaves are shown.