Introduction

Portulaca L. (Portulacaceae) is a monophyletic and cosmopolitan genus (Nyffeler & Eggli 2010), comprising about 100 species mainly distributed in South America and Africa (Ocampo & Columbus 2012; Hernández-Ledesma et al. 2015). It includes rupicolous and terrestrial herbs; usually with fibrous or tuberous roots; succulent, opposite or alternate leaves, with usually axillary trichomes (hairs or scales); flowers arranged in cymose or capituliform inflorescences; and fruit circumscissile dehiscent (Legrand 1962; Geesink 1969; Gilbert & Phillips 2000).

The most recent taxonomic treatments of Portulaca from Brazil were published by Coelho & Giulietti (2010) and Coelho et al. (2010) who recognised 13 species. These species are mainly distributed in the northeast and southeast regions of Brazil, growing in rocky outcrops or shallow soils (Coelho & Giulietti 2006; Coelho & Giulietti 2010). Although together these studies have entailed an extensive effort, several names have been neglected by them, such as P. costata Poelln., P. diegoi Mattos and P. hoehnei D.Legrand.

Portulaca diegoi was described on the basis of specimens collected by Raulino Reitz and Roberto Klein, in Dec. 1958 and Jan. 1959, respectively, from rocky outcrop vegetation in Santa Catarina State of southern Brazil (Mattos 1984a). Mattos (1984a) did not compare these specimens with related species and he did not give information about fruits, roots or seeds, whose characters have taxonomic value in the identification of Portulaca species (Legrand 1962; Ocampo 2018). P. diegoi is currently considered as a rare plant, endemic to the Brazilian Subtropical Highland Grasslands (BSHG) also referred to as the Campos de Cima da Serra (Iganci et al. 2011; Hassemer 2015) and known from just five populations (Mattos 1984b). P. hatschbachii D.Legrand, another rare and endemic species from grasslands on basaltic rocky outcrops in Paraná State, also in southern Brazil (Coelho 2009; Coelho & Giulietti 2010), was described on the basis of specimens collected by Gerdt Hatschbach in Nov. 1957 and Oct. 1960 (Legrand 1962). This species is well known for having thick and elongated roots in relation to its stem size, as well as for the leaves of herbarium specimens turning black (Coelho & Giulietti 2010). Moreover, Legrand (1962) described P. hatschbachii indicating, as main features, the seeds light grey and capsules subspherical and sessile.

As part of the ongoing taxonomic studies of the South American Portulaca species (Ferraz et al. 2022), we here propose to synonymise Portulaca diegoi and P. hatschbachii based on ecological and morphological characters. Moreover, we provide a distribution map, ecological characteristics, an improved description, taxonomic comments, and a conservation status for P. hatschbachii.

Materials and Methods

This study is based on a review of the relevant literature and study of herbarium specimens preserved at ASE, C, CGMS, EFC, FLOR, FUEL, FURB, GB, HAS, HBR, HTL, MBM, UPCB, and UPS, as well as digital images of specimens preserved at B, BM, F, G, GH, HCF, HUEFS, K, L, LIL, MO, MVM, NY, P, RB, S, SP, US, USF, W, and Z (herbarium acronyms follow Thiers 2023, continuously updated).

Macromorphological analyses were performed using a stereomicroscope, digital calliper and the microscope software ZEN lite blue version 2.6 (Zeiss, Germany, https://www.zeiss.com). Micromorphology of seed surfaces was observed using scanning electron microscopy (SEM) FEI Quanta 200 (FEI – Thermo Fischer Scientific, USA, https://www.thermofisher.com). For the preparation of microphotographs, seeds were adhered to stubs with a double-sided carbon tape and covered with gold in a metallizer (BALTEC SCD 050 Sputter Coater, Germany, https://www.baltic-praeparation.de). Morphological terms follow Beentje (2016) and Ocampo (2013). The ecological characteristics and colours of plant structures were observed during floristic surveys carried out between the years 2016 and 2020.

The conservation status was assessed using IUCN (2012, 2022) criteria and guidelines. The Geospatial Conservation Assessment Tool (Bachman et al. 2011) and Google Earth Pro software (Google 2020) were used to calculate the Area of Occupancy (AOO) using a 2 × 2 km2 grid. The distribution map was prepared using ArcGIS (ESRI 2014). The AOO of Portulaca hatschbachii is intrinsically related to the delimitation of rocky ecosystems belonging to the BSHG which, until now have not been recorded north of Paraná, constituting the southernmost limit of this vegetation. These patches of rocky grasslands consist of areas ranging in size from 2,515 m2 to 235,849 m2 and it is, given the resolution it would require, unfeasible here to publish maps that include all 33 locations.

Diagnoses are presented for all species treated, as per the recommendations in Hassemer et al. (2020). The nomenclature used here follows the Shenzhen Code (Turland et al. 2018, hereafter ICN).

Taxonomic Treatment

Portulaca hatschbachii D.Legrand (1962: 105). Type: Brazil, Paraná: Guarapuava, Rio Coutinho, 21 Oct. 1960, Hatschbach 7518 (holotype MVM!; isotypes HAS!, L!, LIL!, MBM!, RB!, SP!, Z!).

Portulaca diegoi Mattos (1984a: 1), synon. nov. Type: Brazil, Santa Catarina: Bom Jardim da Serra, 1300 m, 14 Jan. 1959, Reitz & Klein 4096 (holotype HAS!; isotypes HBR!, US!).

Herbs up to 10 cm high. Taproots thickened, 6 – 30 cm long. Stems green or purplish, decumbent or decumbent to erect, rarely erect, usually very branched. Leaves alternate, subopposite at the apex, entire, simple, fleshy, green in living specimens, black in herbarium material; petiole 0.5 – 1.2 mm long, terete, lighter green than the blade; blades 4 – 14 × 1.0 – 2.2 mm, adaxial surface convex, abaxial surface flat, oblanceolate; base slightly rounded; apex acute, usually purplish, slightly recurved; margin entire; leaf axillary trichomes abundant and denser at the apex, up to 1.5 cm long, lanate, white in living specimens, yellow or brownish in herbarium material. Inflorescence a terminal head, 2 – 5-flowered; subtended by an involucre of 12 – 16 leaves. Flowers bisexual, sessile; sepals 2, unequal, connate at the base, 6.0 – 7.2 × 4.8 – 5.0 mm, ovate, apex acuminate, margins scarious; petals 5 (– 6), quincuncial, magenta, yellow in the adaxial base, 1.0 – 1.8 × 0.6 – 1.2 cm, obovate, apex obcordate, emarginate; stamens 15 – 35, filaments 2.0 – 5.0 (– 7.5) mm long, unequal, yellow, magenta or yellow at the base, turning purplish towards the apex, glabrous; anthers bithecate, 0.5 – 0.8 mm long, yellow, pollen released through longitudinal slits; ovary sub-globose; style 4.0 – 8.6 mm long, magenta, glabrous; stigma magenta, 3 – 7-lobed, 1.2 – 2.0 mm long, linear-lanceolate, the stigmatic surfaces covered with small hairs. Fruit a circumscissile capsule, sessile or pedicellate; pedicel 0.4 – 2.3 mm long; capsule 3.0 – 4.2 × 2.5 – 3.5 (– 4.0) mm; operculum hemispheric, sometimes truncate and asymmetric at the apex, green, shiny; base pale green. Seeds 15 – 30 per fruit, 0.4 – 0.7 mm, subreniform, black or grey, shiny, ornate, individual cells elongated; anticlinal walls undulate with T-, U-, and V-type patterns, the cells toward the peripheral face of the seed par-domed. Figs. 1, 2 and 3.

Fig. 1.
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Holotype of Portulaca hatschbachii (Hatschbach 7518, MVM).

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Fig. 2.
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Portulaca hatschbachii. A habit; B flower; C fruit; D seeds. photos: j. r. ferraz.

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Fig. 3.
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Portulaca hatschbachii. A decumbent individual associated with Bryum argenteum; B decumbent to erect individual growing in shallow soil; C aspect of the leaves and branches when dry; D aggregated individuals. photos: j. r. ferraz.

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recognition. Portulaca hatschbachii can be distinguished from other species of the genus by its decumbent habit, thick and elongate roots, lanate leaf axillary trichomes, oblanceolate leaves with purplish and recurved apices and hemispheric operculum.

distribution. Portulaca hatschbachii occurs in southern Brazil, in the States of Paraná, Santa Catarina and Rio Grande do Sul (Map 1).

Map 1.
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Distributions of specimens of Portulaca hatschbachii (black diamonds) and formerly referred to as P. diegoi (red diamonds) in southern Brazil. Inset map bottom left shows the location in South America. Abbreviations: PR Paraná; SC Santa Catarina; SP São Paulo; RS Rio Grande do Sul.

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specimens examined. brazil. Paraná: Campo Mourão, afloramento rochoso de basalto, 14 Nov. 2013, Lozano et al. 1857 (MBM!); Rio da Vargem, 5 Feb. 1962, Hatschbach 8754 (MBM!, UPCB!); Jardim Albuquerque, 1 Nov. 2005, Geraldino & Oliveira 173 (HCF); terreno frente ao Pesqueiro do Nishida, 27 Aug. 2009, Silva & Siqueira 730 (HCF); Candói, estrada para Fazenda Capão Redondo, 12 Dec. 2013, Engels & Lozano 2153 (MBM!, RB); Lagoa Seca, 26 Oct. 2006, Barbosa & Cunha 1768 (HUEFS, MBM!); ibid. 6 Nov. 2019, Ferraz 808 (FUEL!); Fazenda São Manoel, 21 Aug. 2017, Ferraz 168 (FUEL!); próximo ao Rio Campo Real, 5 Nov. 2019, Ferraz 703 (FUEL!); Cantagalo, km 423, 14 Dec. 1992, Cervi et al. 3876 (MBM!, UPCB!); BR-277, 21 Aug. 2017, Ferraz 169 (FUEL!); Clevelândia, near Sawmill Brandalize, 1 May 1966, Lindeman & Haas 1140 (L, NY, RB); Foz do Jordão, BR-373, 5 Nov. 2019, Ferraz 704 (FUEL!); PR-662, 6 Nov. 2019, Ferraz 845 (FUEL!); Guarapuava, Lagoa Seca, 16 Feb. 1963, Hatschbach 9719 (MBM!); Palmeirinha, 16 Nov. 1957, Hatschbach 4274 (MBM!); Rio Campo Real, 26 Oct. 1980, Hatschbach 43245 (MBM!, USF); Fazenda Capão Redondo, 22 Aug. 2017, Ferraz 171 (FUEL!); Honório Serpa, Pinho Fleck, 22 Aug. 2017, Ferraz 170 (FUEL!); Londrina, Distrito de Lerroville, Campo das Pedras, 17 Nov. 1969, Hatschbach 22892 (MBM!); ibid. 19 Sept 1970, Hatschbach 24866 (MBM); ibid. 5 Sept. 2017, Ferraz 179 (FUEL!); Luiziana, Pedreira abandonada, 8 Aug. 2017, Ferraz 164 (FUEL!); RPPN Depositozinho, 13 Feb. 2009, Siqueira & Santos 136 (HCF); ibid. 8 Aug. 2017, Ferraz 165 (FUEL!); Mangueirinha, Reserva Indígena de Chopinzinho, 15 Sept. 2009, Silva et at. 7355 (MBM!); Reserva Indígena de Mangueirinha, 5 Nov. 2019, Ferraz 721 (FUEL!); Turvo, arredores, 16 April 2009, Caxambu et al. 2607 (HCF); Reserva Indígena de Guarapuava, Rio Marrecas, 13 April 2002, Silva & Poliquesi 3615 (HUEFS, RB); Pedreira abandonada, 20 Aug. 2017, Ferraz 166 (FUEL!). Rio Grande do Sul: Gramado, 12/13 April 1975, Waechter 27 (HAS!). Santa Catarina: Bom Jardim da Serra, 15 Dec. 1958, Reitz & Klein 7945 (HAS!, US); Morro da Igreja, 22 Jan. 1960, Mattos 25033 (HAS!); Urubici, Parque Nacional de São Joaquim, Cascata Véu de Noiva, na estrada de acesso ao Morro da Igreja, 1 Nov. 2014, Fiaschi et al. 4431 (FLOR!); Santa Bárbara, próximo ao alojamento, Parque Nacional de São Joaquim, 25 Jan. 2019, Funez et al. 8649 (FURB!).

habitat. This species is endemic to the BSHG and often grows in association with Bryum argenteum Hedw. (Fig. 3A), Sphagnum recurvum P.Beauv. and S. cuspidatum Ehrh. ex Hoffm. in shallow soils and on basaltic rocky outcrops at elevations of 549 – 1400 m.a.s.l. These basaltic rocky outcrops are surrounded by Araucaria forest, Seasonal Semideciduous forest and plantations of Pinus taeda L. and P. elliottii Engelm. In undisturbed rocky outcrops in north and central regions of Paraná, Portulaca hatschbachii forms dense and aggregate populations (Fig. 3D). However, P. hatschbachii is rare and occurs more sparsely in rocky outcrops disturbed by mining. We found several edaphically specialised species, endemic to the BSHG, occurring sympatrically with P. hatschbachii, such as Dyckia walteriana Leme, Eryngium corallinum Mathias & Constance, Mimosa hatschbachii Barneby, Nierembergia hatschbachii A.A.Cocucci & Hunz., Nothoscordum exile Ravenna, N. gracilipes Ravenna, Paspalum redondense Swallen, Stylosanthes vallsii Sousa Costa & Van den Berg and Zephyranthes paranaensis Ravenna.

conservation status. We provisionally assess the conservation status of Portulaca hatschbachii as Critically Endangered [CR B2ab(i,ii,iii,iv)] (IUCN 2012, 2022). We found 33 populations, giving an AOO of c. 4 km2. Between Aug. 2016 and Dec. 2021, eight of these populations were eradicated, indicating the considerable fragility of these grassland ecosystems. At this rate of population loss (1.3 per year), if effective conservation measures are not put in place, the remaining, known populations could become extinct within the next 30 years. The populations are mainly (94%) distributed in unprotected areas, only two are in protected areas, the National Park of São Joaquim (Santa Catarina) and the Private Natural Heritage Reserve Depositozinho (Paraná). The major threats to P. hatschbachii include its fragile habitat, severe population fragmentation, low levels of population genetic diversity (Feliciano et al. 2022), decline in the quality of its habitat caused by mining, invasion by alien species, especially the grass Megathyrsus maximus (Jacq.) B.K.Simon & S.W.L.Jacobs and Pinus taeda, fire, cutting and predation by cattle.

phenology. Flowering and fruiting from August to April. Only 1 (– 2) flowers per inflorescence open in the morning, between 10:00 – 10:30 am, and close about 5h after anthesis. The seeds are wind dispersed. The leaves and branches turn black in late May and early June (Fig. 3C), disappearing entirely in July. After the dry season (June – August), plants produce new branches and leaves.

notes. Probably due to general morphological similarities, an isotype Reitz & Klein 4096 (US2323257) and a paratype Reitz & Klein 7945 (US2323626) of Portulaca diegoi were originally identified as P. hatschbachii. The analysis of the types and protologue of P. diegoi shows that this species has the same leaf, flower, fruit, and root morphology as P. hatschbachii. In both, the adaxial surface of leaves are convex, abaxial surfaces are flat and the blade is oblanceolate; sepals are ovate with margins scarious and petals are obovate with apices obcordate and emarginate; capsules are subspherical and the operculum is hemispherical; and the roots are tuberous, thick and elongated. We found that, in actuality, the range of variation of all the characters of P. diegoi overlaps with that of P. hatschbachii, and that the leaves of the former species also turn black in herbarium material (Fig. 4). Both species inhabit shallow soils and basaltic rocky outcrops, with P. hatschbachii found at elevations of 549 – 1100 m.a.s.l. and P. diegoi at elevations of 1200 – 1400 m.a.s.l.

Fig. 4.
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Holotype of Portulaca diegoi (Reitz & Klein 4096, HAS).

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Seed morphology is highly diverse in Portulaca (Ocampo 2013; Ocampo 2015) and it is widely applied in the taxonomic context (Domina & Raimondo 2009; Danin et al. 2016; Santos et al. 2016; Amini Rad et al. 2017). The seeds of Portulaca hatschbachii and P. diegoi have the same features (Fig. 5). Following Ocampo’s (2013) terminology for morphological features of seeds, this species has seeds which are subreniform, with anticlinal walls undulate with T-, U-, and V-type patterns and the cells toward the peripheral face of the seed are par-domed.

Fig. 5.
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SEM images of seeds. General aspect of seed (A and C) and anticlinal walls undulate with T-, U-, and V-type patterns (B and D) in Portulaca hatschbachii (A, B, Ferraz 167 [FUEL]), and former Portulaca diegoi (C, D, Funez et al. 8649 [FURB]).

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Therefore, based on micro and macromorphological and ecological characters, we conclude that Portulaca diegoi and P. hatschbachii should be considered synonyms. In accordance with Art. 11.4 of the ICN, P. hatschbachii, as the earlier name, 1962 vs 1984, has priority and must be adopted as the correct name for the species.

According to Legrand (1962), Portulaca hatschbachii is characterised by the seeds light grey and the capsule sessile and subspherical. In our collections of specimens in the locus classicus, we also found individuals with black seeds and pedicellate fruits. Legrand (1962) also stated that P. hatschbachii has morphological affinities with P. eruca Hauman which is endemic to Argentina and Paraguay and P. elatior Mart. ex Rohrb. which occurs in the Caribbean region and tropical South America (Bolivia, Brazil, Colombia and Venezuela). However, based on our observations, P. hatschbachii can be distinguished from P. eruca by its leaf shape (oblanceolate vs subulate), leaf axillary trichomes (lanate vs hirsute) and branching and habit (very branched and decumbent or decumbent to erect vs usually simple and erect). P. hatschbachii can be easily distinguished from P. elatior by its height (5 – 10 cm vs 12 – 40 cm), habit (decumbent or decumbent to erect vs erect), leaf shape (oblanceolate vs linear-lanceolate), and roots (tuberous vs fibrous). Table 1 summarises the comparison of P. hatschbachii to both similar species and provides some additional details.

Table 1. Morphological comparisons of Portulaca hatschbachii, P. eruca, and P. elatior.
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