Trichocline maxima Less., Linnaea

Pasini, Eduardo, Bonifacino, José Maurício & Torchelsen, Fábio Piccin, 2021, Trichocline maxima (Compositae, Mutisieae) a rare Pampean daisy rediscovered after 70 years in Uruguay, Iheringia, Série Botânica (e 2021006) 76, pp. 1-6 : 2-5

Trichocline maxima Less., Linnaea 5: 290. 1830.

Type: BRAZIL. “ Brasilia meridionalis . s.l., s.d., Sellow s.n. ”. (Lectoype, designated here K-504286 [image!]; Isolectotypes G-308259 [image!], HAL-113007 [image!], P-703278 [image!]).

Figs. 1 , 2 .

Perennial, scapose herbs with rosulate leaves, up to 85 cm high. Xylopodium up to 12.5 cm long, more or less cylindrical. Leaves petiolate; petiole 2–7 cm long, blade 20–30 × 3–4 cm, obovate or oblanceolate, base attenuated to cuneate, apex acute or obtuse, margin entire or lobate, lobes (when present) 3–5-paired, 0.5–3 cm long, rounded, glabrous, papyraceous. Floral scape 45–80 cm long, erect, ebracteate, glabrescent to glabrous. Involucres 2–3 × 1.5–2.5 cm, hemispheric, phyllaries 5–8-seriate, adaxial surface tomentose; outer 6–7 × 5–7 mm, ovate, apex obtuse to acute, adaxial surface woolly; middle ovate-lanceolate, 9–12 × 4–6 mm, apex obtuse, tomentose on the adaxial surface; inner 13–16.5 × 4–6.5 mm, ovate-lanceolate, apex acute, glabrous. Florets dimorphic; ray florets female, uniseriate, yellow, outer conspicuous, spreading, apices very short 3-toothed, inner of two long linear spiraled lobes, ca. 25, corolla bilabiate-liguliform, yellow, tube 7–10 mm long, abaxial lip 10–21 × 2.5–3 mm, linear to lanceolate, tomentose, adaxial lip ca. 4.5 mm long, staminodes 5, 3–4 mm long, apex acute, base attenuate or sagittate; style 8–12 mm long, style branches ca. 1 mm long; disc florets bisexual, corolla bilabiate-tubulose yellow, tube 11.7–14.5 mm long, abaxial lip 3-toothed, 3–4 mm long, recurvate, adaxial lip 2-toothed, 3–3.5 mm long, anthers 9.4–12 mm long, basal appendages papillose, style 17.5–19 mm long, style branches ca. 1 mm long. Achenes ca. 1 cm long, cylindrical or ovoid; twin hairs densely set; pappus uniseriate, 13–15.7 mm long, bristles barbellate.

Distribution and ecology: South Brazil (Rio Grande do Sul State) and Uruguay ( Fig. 3 ). The species inhabits rocky outcrops and sandy soiled grasslands at low elevation areas of the Pampean phytogeographic province ( Cabrera & Willink 1973). Previous studies indicated that the species was probably extinct in Brazil ( Zardini 1975; Pasini & Ritter 2012), and in fact, the only three records in this country were made almost 190 years ago; one of them is the type specimen that was indicated by Lessing (1830), and is located at K, G, HAL and P. The other two collections were cited by Malme (1931) as follows: “ Inter Rio Pardo et Bagé ( F. Sellow 1831); etiam ab Isabelle lecta, loco non indicato ( A. Isabelle 1835)”, of which we were not able to find. The species records in Uruguay are also scarce and are restricted to the northern region of the country (Departments of Rivera and Tacuarembó), which shares the same floristic characteristics with the southern extreme of Brazil (State of Rio Grande do Sul). Prior to our rediscovery, the latest record was almost 70 years ago (Osorio s.n. MVM 13902). We could track the species habitat, following the information of its records from Uruguay, and locate it in the department of Tacuarembó, Paso Ataques. The subpopulation was found in shrubby grassland with rocky outcrops and sandy soil. The species habitat is extremely endangered due to human impact, like intensive silviculture and uncontrolled use of grazing. In fact, the whole population was surrounded by Eucaliptus sp. plantation.

Phenology: The species bloom from late December to March.

Conservation status: We consider the species Critically Endangered ( CR) by the IUCN’s (2011) categories, according to the following criteria and subcriteria: A 4 (c) (e); B 2 a: A 4. We project that the subpopulations suffered from a drastic size reduction in the last 100 years, due to decline of habitat quality. This could be related to the human impacts along the species range areas. There are vast areas of Pinus spp. plantation in northern Uruguay, which for the genus Trichocline as a whole, could lead to local extinctions. Besides that, this particular species presents a large floral scape and conspicuous ray florets, and can be easily spotted in nature, a fact that could potentially be related to its exploitation for ornamental purposes; B 2 a – the total extent of occurrence of the species was severely fragmented by the agricultural and silvicultural systems. Furthermore, the only register of the species in Brazil is from almost 200 years ago.

Taxonomy and lectotypification: Christian Friedrich Lessing described Trichocline maxima in 1830, using a collection of Friedrich Sellow from Brazil. This botanist first collected the species around the year 1820 in the “Plata” region, which today is comprised by the territories of South Brazil (State of Rio Grande do Sul), Uruguay and northeast Argentina. Plenty of information is lacking from some of the species collected by this botanist during his stay in South America, in particular for Brazil. Some of his informations written on the herbarium sheets are difficult to decipher, and different localities are often informed in the same syntypes material. All of this is because the botanist had a tragic and early death in Brazil and therefore could not complete the information for each collection made by him. During the revision of the digitalized material of the genus Trichocline , we could identify three syntypes of this species, one in K, one in G and another in P, all collected by Sellow. In the labels of some of them, the indicated locality is simply Brasilia ( Brazil) (e.g. G-308259), which is in accordance with the protologue of the species in Lessing (1830), however in some other specimens the locality Brasilia meridionalis is cited (e.g. K-504286). We do not believe this is a significant difference that indicates that the syntypes were collected in different places and times, and therefore we consider they all belong to the same collection. In addition to that, by the time Sellow collected the species, the borders between Uruguay and Brazil were not the same as today, therefore it could have been first collected in Uruguay.

Since the author did not specified which specimen is the holotype, we chose the one deposited in K as the lectotype (K-504286). This specimen is the one that is most informative and well preserved.

Trichocline maxima is a conspicuous scapose herb that can be easily distinguished from the other species of the genus by its smooth and glabrous 55–80 cm long floral scape, ovate phyllaries and glabrous leaves. During the vegetative stage, T. maxima can be misidentified by Trichocline cisplatina E. Pasini & Ritter , another Uruguayan species that also presents glabrous leaves with lobate margin and rounded lobes, however the second one has lobes bending backwards and form secondary lobes. The epithet T. maxima refers to the species large scape.

Additional examined material: BRAZIL. RIO GRANDE DO SUL: s.l., 1835, A. Isabelle s.n. ( K, n.s.). URUGUAY. RIVERA: Paso Ataques , I.1944, J. Chebataroff 9112 ( LP); XII.1945, A. Lombardo 4570 ( MVJB); 22.IV.2014, E. Pasini, J.M. Bonifacino, F.P. Torchelsen 1019 ( ICN 178180 ); Rincón de La Laguna , 14.II.1947, H. Osorio s.n. ( MVM 13902 ) .

Figures

Figure 1. A-G. Trichocline maxima. A. General view of the species habit; B. Capitulum; C. Involucre; D. Detail of achene and pappus; E. Detail of rosette leaves, scapes and xylopodium; F. Detail of the rosette and lobate leaves; G. Habitat. Photos credits: A-C, F and G by José M. Bonifacino; D by Fábio P. Torchelsen.

Figure 2. A-E. Illustration of Trichocline maxima. A. Habit; B. Outer to inner phyllaries; C. Ray florets; D. Disc florets; E. Achene.Illustrations A–E were made by Edson Luis de Carvalho Soares and adapted from Pasini & Ritter (2012). José M. Bonifacino drew the illustration of the achene E.

Figure 3. Distribution map of Trichocline maxima. The orange dot represents the latest record of the species that is reported in this work. The black dot in Uruguay is from collections cited in the additional examined material section. The black dot in Brazil represents the possible location of Malme’s (1931) citation of a Sellow’s collection: Inter Rio Pardo et Bagé.