Eleocharis serrae-novae Atuesta & R.Trevis., 2025

Atuesta, Duvier J. & Trevisan, Rafael, 2025, A new species of Eleocharis (Cyperaceae) from the campos rupestres of northern Minas Gerais, Brazil, Phytotaxa 683 (2), pp. 171-176 : 172-174

Eleocharis serrae-novae Atuesta & R.Trevis. , sp. nov. ( Figure 1 )

Type:— BRAZIL. Minas Gerais: Porteirinha, parque estadual de Serra Nova e Talhado, Cachoeira de Briz, 15°41’45’’S, 42°50’36’’W, 849 m, 02 April 2022, M. Verdi et al. 8592 (holotype: FLOR!, isotypes: RB, SPF).

Ab omnibus speciebus notis culmo 0.1–0.2 mm lato, vagina saepe inflata, glumis stramineis cum maculis longitudinalibus vinaceis marginibus hialinis et apicibus emarginatis, spiculis 30–50 floribus, acheniis cancellatis differt.

Perennial, rhizomatous, dwarf, slender herbs. Rhizomes short, non-lignified. Culms capillary, erect or somewhat curved, 5–12 cm × 0.1–0.25 mm, quadrangular in cross section, sulcate, not septate, smooth, light green to stramineous. Sheaths tubular, 1–1.8 cm long, basally firm and dark reddish, apically stramineous to green, 3-nerved, the midrib proximally keeled, the lateral veins acrodromous, apex oblique acute to acuminate, somewhat inflated, margins membranaceous. Basal spikelets absent. Spikelet stramineous, 4–7.5 mm × 2–2.2 mm, oblong to oblong-lanceolate, 30–50-flowered, not proliferous. Glumes membranaceous, spirally arranged, loosely imbricated, smooth, midrib prominent and slightly keeled. Lower glume elliptic, 2 × 1 mm, sterile, persistent, sides hyaline, keel green to stramineous, apex obtuse to retuse. The second lowest glume is quite similar to the lowestmost and it is just at the same level, but it is fertile and usually caducous. Upper glumes elliptic, 1.5–1.8 × 0.7–1 mm, the basal ones sometimes caducous ( Figure 2. A ), apex obtuse to emarginate, keel green or stramineous, the margin hyaline with vinaceous longitudinal bands, membranous c. 0.3 mm wide. Stamens 2, anthers linear, 0.4–0.5 mm long, dark brown; filaments 1.5 mm long, translucent. Hypogynous bristles absent. Style trifid, stigmatic branches subequal to longer than the style, 0.5 mm long. Stylopodium conical, 0.1 mm long. Achene body 0.4–0.6 × 0.3–0.4 mm, obovate, trigonous, the angles prominent and the sides convex, gray, surface cancellate, with 5–6 vertical rows of cells on each side.

Distribution and Habitat:— This species is known only from the Parque Estadual de Serra Nova e Talhado in the north of Minas Gerais state ( Brazil). It grows in areas of rupestrian grasslands, associated with stony, sandy soils.

Conservation Status:— According to the criteria of the IUCN (2012), Eleocharis serrae-novae is considered Data Deficient (DD), as there is no appropriate data on its population status and distribution. This species is only known from the type locality, the Parque Estadual de Serra Nova e Talhado, in the north of Minas Gerais ( Brazil). This area is dominated by Rupestrian grasslands vegetation and is part of the biodiversity conservation system of Brazil: Sistema Nacional de Unidades de Conservação da Natureza —SNUC. The occurrence of Eleocharis serrae-novae in a protected area could contribute to its conservation.

Collectors indicate that the species is locally frequent, which suggests good population status. However, it is necessary to know its threats, population trends, and habitat quality to determine its risk of extinction and to elaborate appropriate actions. Rupestrian grasslands are recognized as areas of high diversity and endemism ( Giulietti et al. 1997, Silveira et al. 2016). According to Fernandes et al. (2014) and Silveira et al. (2016), that ecosystem is under threat by multiple factors including increase in fire events, introduction of exotic species, uncontrollable ecotourism, mining, and climate change. Finally, the dwarf species of Eleocharis are typically poorly understood and frequently misidentified. To accurately determine their geographic range (Extent of occurrence and Area of occupancy), additional taxonomic studies and field expeditions are required.

Etymology:— The name of the species refers to its type locality, Parque Estadual de Serra Nova e Talhado (PEST). This park was established in 2003 under the name Parque Estadual de Serra Nova, and was renamed PEST in 2017. The epithet was created based on the unchanged part of the name, “ Serra Nova”. This was done to emphasize the importance of such conservation units in protecting the Brazilian biota, as well as their significance in environmental education and ecological tourism. Thus, these conservation units play a fundamental role not only for scientific purposes but also in disseminating scientific knowledge and fostering the appreciation of native biota among local communities. Within these areas, new species are continuously being described, further reinforcing their relevance.

Taxonomic relationships:— Eleocharis serrae-novae resembles E. nigrescens Kunth (1837: 157) by having stramineous glumes with an obtuse to emarginate apex, which are usually caducous, but differs in that it has oblong to oblong-lanceoloid spikelets and cancellated achenes. The shape of the stylopodium and the longitudinally ribbed achenes resemble those of E. bahiensis Simpson (1988: 127) , but that species has aristate sheaths, dark chestnut glumes, and trabeculate fruits. The achenes are also similar to those of E. morroi Simpson (1988: 131) ; however, in that species the achenes are longitudinally rugose, the glumes chestnut brown, and the lowest 2 glumes fertile. Another dwarf species characteristically with stramineous glumes and a minutely conical stylopodium is E. angustispicula Trevisan (2010: 505) but it differs from E. serrae-novae by having 10–25 flowers and achenes finely reticulate ( Table 1).

According to the classification system of González-Elizondo & Peterson (1997), Eleocharis serrae-novae should be placed in Eleocharis subg. Eleocharis sect. Eleocharis ser. Tenuissimae due to its dwarf size and capillary culms (0.1-0.2 mm width), 3-branched stigma, and trigonous achenes with a deeply cancellated surface. However, its affinity with E. bahiensis and E. morroi casts doubt on its position in this group. Although Trevisan & Boldrini (2010) considered both species as part of Tenuissimae , these species present characteristics that are uncommon within that series. The former has achenes with longitudinal rows of trabeculae, and the latter has the lowest 2 glumes fertile ( Simpson 1988). These characteristics are typical of members of E. sect. Scirpidium ( Nees 1834: 293) Benth & Hook (1883: 1047) ( González-Elizondo & Peterson 1997). More studies are required to determine the phylogenetic position of these species and their relationship with Eleocharis serrae-novae .

Finally, it is noteworthy that the achenes of Eleocharis serrae-novae display three prominent angles when observed under a stereomicroscope. However, when examined with SEM, these angles become inconspicuous, revealing a pattern of regular ribs ( Figure 2. B ). This highlights the challenges of studying diminutive plants and emphasizes the necessity of employing various microscopy techniques to accurately describe fruit surface morphology in Cyperaceae .

Figures

FIGURE 1. Eleocharis serrae-novae.A. Habit. B. Sheath apex, dorsal view. C. Sheath apex, ventral view. D. Spikelet. E. Glume, dorsal view. F.Achene. (Drawn by D.J. Atuesta from the holotype.)

FIGURE 2. Eleocharis serrae-novae. A. Spikelet showing the rachilla. B. SEM of the achene, X160. C. SEM magnification of the achene surface, X400. Scale A: 2 mm, B: 0.1 mm, C: 0.05 mm.