Parodia hofackeriana A. S. Oliveira & R. Pontes, 2023

Oliveira, Anabela Silveira De & Pontes, Rodrigo Corrêa, 2023, Parodia hofackeriana (Cactaceae-Notocacteae), a new species from southwest of Rio Grande do Sul, Brazil, Phytotaxa 598 (4), pp. 283-292 : 284-290

Parodia hofackeriana A. S. Oliveira & R. Pontes sp. nov. ( Figs. 1A–D , 2A–D and 3A–D ).

Type:— Brazil. Rio Grande do Sul: Santana do Livramento , 265 m, 12 October 2015, Oliveira & Deble 84b (holotype PACA!, isotype PACA!) .

Diagnosis (latin):— Parodia hofackeriana similis est Parodia mueller-melchersii subsp. mueller-melchersii a quo magnitudine minore differt (9 × 10 vs. 20 × 15 cm), figura caulis (globoso-cylindraceo vel brevissimo vs. rotundato vel elongato); costarum numero minus (18–20 vs. 20–25); aculeis centralibus (3–4 vs. 1); plures aculei radiales (13–19 vs. 15–18), flores maiores (usque ad 6 vs. usque ad 5 cm).

Diagnosis (english):— Parodia hofackeriana is similar to Parodia mueller-melchersii subsp. melchersii from which differs by its smaller size (9 × 10 vs. 20 × 15 cm), shape of the stem (globose to short-cylindric vs. rounded to elongated); less number of ribs (18–20 vs. 20–25); number of central spines (3–4 vs. 1); number of radial spines (13–19 vs. 15–18), larger flowers (up to 6 vs. up to 5 cm).

Description:— Saxicolous plants with succulent habit, globose to short-cylindrical, 9–10 cm high × 7–9 cm wide, single, not producing offsets naturally (excepted when the areoles are damaged), epidermis dark-green, opaque, slightly squamose, with umbilicate apex; with 18–20 ribs, straight, well-defined but slightly tuberculate, with little sinuses between successive tubercles, 0.1–0.2 cm tall × 0.9–1.1 cm thick, with almost with no proeminent edges below the areoles; areoles located at the slightly sinuses between consecutive tubercles, rounded, 0.3–0.5 cm diameter, densely set, 0.7–0.8 cm apart, with whitish wool when juvenile, later glabrescent; spines: prominent, acicular, straight, pungent; radial spines 11–15–(20), 0.4–0.9 × 0.03–0.04 cm; reddish to grey (when older); central spines 1–2, 1.0–1.5 × 0.07–0.10 cm dark redish to grey (generally when older), easly distinguished from the radials, longer and thicker; flowering areoles producing longer and thicker spines, up to 2 cm, like observed in wild; flower buds with a dense cover of white to pale brown woll and bristles; flowers subapical, diurnal, opening along several days, flowering 8 hours after the sunrise and closing circa four hours later, self-fertile; flowers infundibuliform, to 4.0– 4.5 cm, 5–6 cm in diameter ( Fig. 3 ); floral tube to ca. 1 cm; internal walls pale yellow and external walls yellowish green, with triangular bract scales subtending areoles that bear white to pale brownish hairs and long reddish brown bristles to 1.5–2.0 cm; tepals pale-yellow, perianth multiseriate, segments pale-yellow oblanceolate; stamens numerous, spreading, arranged along the inner walls of the floral tube and around the style; filaments with 1.6–1.9 cm, style pale - yellow, ca. 1.6–2.0 cm; stigma lobes exserted, 9–10, light-purple; fruit 2.0–2.5 × 1.0–2.0 cm, green to dark purple, pericarpel with areoles bearing long brown hairs and bristles, dehiscing at the base and later falling off, pulp white; dry perianth remnants either persistent on the fruit or falling off; seeds broadly oval, 0.9–1.2 mm broad, 1.1–1.4 mm long, 1.1–1.3 mm high, dark brown, matt, border little expanded around hilum, testacells uniform, elongated, antilclinal boundaries cannelled, cells on the bottom black, on top light brown, hilum basal, superficial, hilum-microphylar region oval, microphyle conjunct ( Fig. 4 ).

Etymology:— The specific epithet honors to Andreas Hofacker, researcher of Cactaceae of Brazil.

Phenology:— Flowering season is September–October, whereas mature fruits can be found in November– December. The flowers, in cultivation, open only on very hot days, around 11 a.m., closing about 4 hours after the beginning of the anthesis.

Distribution and habitat:— The species was found in three isolated locations in the area between the municipalities of Alegrete, Rosário do Sul and Santana do Livramento ( Fig. 5 ), possibly endemic to the southwestern region of Rio Grande do Sul, Brazil. Parodia hofackeriana grows on rocky outcrops of volcanic origin (basalt) on hills, among fragments of weathered rock, with the presence of humus and organic matter. It is sympatric with Frailea perumbilicata F. Ritter (1970:125) and Gymnocalycium uruguayense (Arechavaletae 1905: 218) Britton & Rose (1922: 172) . Nearby, F. pumila ( Lemaire 1838: 21) Britton & Rose (1922: 209) , Parodia glaucina , P. mammulosa , P. mueller-melchersii subsp. mueller-melchersii , P. orthacantha , P. tenuicylindrica , and P. erinacea are growing, in the same environmental conditions.

Conservation status:— Firstly, Parodia hofackeriana was located by the authors in 2015. With complementary observations, carried out during 2019, 2020, 2021 and 2022, it was concluded that the taxon is an independent species. No morphological deviations were observed in its population, showing that it is a species with peculiar characteristics. So far, it is recognized for three localities, ca. 80 km apart, found in a rocky region, between fragments of basaltic rock with grasses. This area is inserted in the Pampa, a biome internationally known for biotic endemism ( Andrade et al. 2023).

In the area, pastures with cattle and sheep are frequent, which can be potential threats to the survival of these populations. With these findings, it is concluded that this new taxon is endangered in their locations. Following the criteria of IUCN (2022), we propose that Parodia hofackeriana has to be considered Critically Endangered (CR), based on geographic distribution, occupation area, and population size [CR B1+B2b (i,ii,v) + c (iv) +C2a(i),b].

Taxonomical notes: — Parodia hofackeriana is closely related to the P. mueller-melchersii subsp. mueller-melchersii due to the presence of tubercular ribs, larger pale-yellow flowers, and hemispherical berry-like fruits. P. hofackeriana is distinguished from P. mueller-melchersii by the number and shape of ribs (18–20 vs. 20–25); shape of central spines (hemispheric vs. flat); color of central spines (reddish-brown to grey vs. whitish-horn-colored) and color of radial spines (reddish-brown to grey-brown vs. yellowish white).

From Parodia mammulosa , it is distinguished by the greater number of ribs (18–20 vs. 14–20), shape of central spines (hemispheric vs. flat); color of central spines (reddish-brown to grey vs. whitish-horn colored, brown-red to purplish-brown, often lighter at the tip); shape of radial spines; color of radial spines (reddish-brown to grey-brown vs. yellowish to reddish) brown. It should be noted that the species in question differs from related species also by flowering season, being earlier than P. mammulosa and P. mueller-melchersii subsp. mueller-melchersii . It blooms at the beginning of spring (September–October) bearing fruits in November–December. The Table 1 includes additional differences between P. hofackeriana and its related species. P. mammulosa and P. mueller-melchersii subsp. mueller-melchersii were also found in the immediate vicinity of the type location (circa 1 km away). No transitions and hybrids were observed and all taxa are clearly distinguishable.An important feature for differentiating individual species is the issue of hybridization of taxa that are sympatric or occur close together. If hybrids are not found, they can be considered independent taxa ( Hunt et al. 2006: 4). Thus, P. hofackeriana should be recognized as a separate taxon. Investigations were also carried out in nearby locations, with the aim of finding new habitats for P. hofackeriana , but such actions were unsuccessful. Due to accessibility, sometimes difficult, the possibility of the existence of the species in other areas not yet investigated can not be ruled out. Morphological differences ( Tab. 1 and Fig. 6 ) and proximity to populations of Parodia mammulosa and P. mueller-melchersii subsp. mueller-melchersii make it necessary to recognize the taxon as an independent species.

Additional materials examined:— Parodia mammulosa . BRAZIL. Rio Grande do Sul: Quaraí, BR 293, close to Sarandi II, 15.XI.1016, Oliveira & Deble ex. cult. 127az ( PACA); Santana do Livramento, Cerros Verdes , 02 October 2018, Oliveira & Deble ex. cult. 128az ( PACA) .

Parodia mueller-melchersii . BRAZIL. Rio Grande do Sul: Alegrete, Caverá , 31 March 2018, Oliveira & Deble ex cult. 70b ( PACA) ; Bagé, Passo do Cação , out 2018, Oliveira & Deble ex cult. 96b ( PACA) ; Quaraí, Cerro Chato , 22 March 2017, Oliveira & Deble ex cult. 56b ( PACA) ; between Sarandi II e Sarandi III, 12 November 2017, Oliveira & Deble ex cult. 51b e 52b ( PACA) . URUGUAY. Artigas, Masoller, east of Cuchilla de Belén , 21 March 2017, Oliveira & Deble ex. cult. 82b ( PACA) ; Tacuarembó, Valle Eden , 12 October 2016, Oliveira & Deble ex cult. 100 ( PACA) .

Figures

FIGURE 1 (A–D). Parodia hofackeriana (Oliveira & Deble 84b) in habitat. A. Side view; B. Top view; C. Overview of the population. D. Habitat (Photography: R. Pontes).

FIGURE 2 (A–D). Parodia hofackeriana (Oliveira & Deble 84b). A. Juvenile plant. B. Plant with buds. C. Plant with closed flowers. D. Plant with a fruit. (Photography: R. Pontes).

FIGURE 3 (A–D). Parodia hofackeriana (Oliveira & Deble 84b). A. Cultivated specimen; B. Detail of specimen apex in lateral view; C. Detail of the areoles; D. Longitudinal flower cut, outside (Photograph by R. Pontes).

FIGURE 4. Seeds of Parodia hofackeriana, P. mammulosa and P. mueller-melchersii: hilum micropylar region, top and side view, with details of seed coat (testa). (Photography D. Metzing).

FIGURE 5. Distribution map of Parodia. hofackeriana and P. mueller-melchersii subsp. mueller-melchersii (Map by R. Pontes).

FIGURE 6 (A–F). Morphological differences between Parodia mueller-melchersii subsp. mueller-melchersii and P. mammulosa in their ribs, spines, buds and flowers. A. P. mueller-melchersii subsp. mueller-melchersii ribs and spines; B. P. mammulosa ribs and spines; C. P. mueller-melchersii subsp. mueller-melchersii flower buds; D. P. mammulosa flower buds; E. P. mueller-melchersii subsp. muellermelchersii flower; F. P. mammulosa flower. (Photograph by R. Pontes).