Phyllanthus graminoides P. Orlandini, 2024

Orlandini, Priscila, Cordeiro, Inês, Lombardi, Julio Antonio, Zavatin, Danilo Alvarenga & Souza, Vinicius Castro, 2024, A phyllocladiferous new species of Phyllanthus (Phyllanthaceae) from Minas Gerais, Brazil, Phytotaxa 661 (3), pp. 293-300 : 294-298

Phyllanthus graminoides P. Orlandini sp. nov. ( Figures 1 , and 2)

Type:— BRAZIL. Minas Gerais. Rio Pardo de Minas: Parque Estadual da Serra Nova, da Ilha das Cabras até o Ribeirão São Gonçalo, 15°34’48.2’’S, 42°43’51.6’’W, 782–887 m a.s.l., 25 March 2012, fl., fr., J. A. Lombardi, M. N. Saka & D. A. Araújo 9141 (holotype: HRCB 57155 !; isotype: BHCB 171076 !) .

Diagnosis:— Phyllanthus graminoides is similar to P. chapadensis , P. choretroides , and P. goianensis , since all four species have cylindrical phylloclades. However, the phylloclades of P. choretroides and P. goianensis (mostly) emerge from a short main stem giving the plant a clump-like appearance (vs. phylloclades that emerge sparsely from ramifications of a long main stem in P. chapadensis and P. graminoides ). Furthermore, in P. graminoides , the stipules are linear with entire margin (vs. triangular stipules with lacerate margin in P. chapadensis , narrowly oval to elliptical with denticulate margin in P. choretroides , and wide-triangular, with entire to lacerate margin in P. goianensis ). The staminate flowers in P. graminoides , P. goianensis and P. choretroides have 5 sepals (vs. 6 in P. chapadensis ) and P. graminoides and P. goianensis have 3 stamens joined by the connective and anthers dehiscing vertically (vs. 3 stamens joined by the connective and with anthers dehiscing obliquely in P. chapadensis , and 2 stamens joined by the connective and with anthers dehiscing horizontally in P. choretroides ).

Description:— Subshrubs ca. 1.5 m tall, densely ramified, phyllanthoid branching, with stem profusely branched, branching starting at about 1 third of the stem height up to half of the main branch that is cylindrical, woody, secondary branches transformed into cylindrical phylloclades, glabrous, straight and ascending, non-plagiotropic, light green, truncated at apex, or obtuse, base attenuate, 20–56 × ca. 0.1 cm, striated with linear and prominent, fine streaks not converging into pairs for the margins, with 3–7 nodes per phylloclade, internodes 0.5–1 cm long. Cataphylls and eophylls not seen. Stipules 0.1–0.2 × 0.2–0.3 cm, triangular, acuminate apex, straight base, entire margin, persistent, usually inconspicous. Leaves 1–2 × 2 mm, fleshy, elliptical, ericoid, brochidodromous, glabrous, acuminate, shortly mucronulate, margin entire, sessile or with petiole up to 1 mm long, cylindrical, greenish. Inflorescences unisexual with cymules in an appearance glomeruliform. Staminate cymules with 2 or 3 flowers; subtended by bracts 0.1–0.3 × 0.2– 0.3 mm, narrowly triangular, acuminate apex, glabrous, greenish, non-congested, membranaceous, entire or undulate at the margin. Pistillate cymules with solitary flowers, subtended by bracts 1–0.3 × 0.2–0.3 mm, membranaceous, narrowly triangular, acuminate apex, glabrous, greenish, margin entire or undulate. Staminate flowers 2–4 mm long, pedicel 1–2 mm long; sepals 5, white, 0.2 × ca. 0.1 cm, oval or elliptical in a single whorl, membranaceous, cream, equal, margin entire, apex rounded or acute; nectary of 5 globose rounded glands, joined to the base of each sepal, yellowish; stamens 3, yellow, filaments connate into a column 1 mm long, anthers up to 0.5 mm long, fused by the connective, vertical or obliquely dehiscent. Pistillate flowers 7–10 mm long, pedicels 6 mm long; sepals 5, white, 3–4 × 1–2 mm, oval in a single whorl, membranaceous, similar to the staminate ones, apex rounded, margin entire; disk annular with undulate margin, yellowish; styles 3, free, the internal stigmatic portion along the styles divergent, curved; ovary 0.5–0.9 mm long, globose, glabrous, greenish to yellowish, slightly trigonous. Capsules 2–3 × 3 mm, subglobose, smooth, greenish, sepals and stigmas persistent in the ripe fruit; Seeds 2 × 1.5–2 mm, trigonous, brownish, smooth. Carpophorous persistent.

Distibution and habitat:— Phyllanthus graminoides is endemic to rocky outcrops of the campo rupestre vegetation, in the State of Minas Gerais, in the Parque Estadual da Serra Nova ( Figure 3 ). The Park area spans across the municipalities of Mato Verde, Porteirinha, Riacho dos Matos, Rio Pardo de Minas, and Serranópolis de Minas (IEF-MG 2023). The holotype was collected in Rio Pardo de Minas, specifically in an area situated between Ilha das Cabras and Ribeirão São Gonçalo, at an altitude ranging from 782 to 887 meters.

Phenology:—Collected with flowers and fruits in March.

Preliminary conservation status:— Phyllanthus graminoides can be considered a Critically Endangered (CR) species. To date, it has only been collected in one region of Minas Gerais. Due to the fact that there is only one single collection of material, it was not possible to calculate the EOO. The estimated AOO is 4 km ². In this way, the species can be classified within criterion B, being classified as CR B2ab(iv).

Etymology:—The specific epithet “graminoides ” is a reference to the general appearance of the plant, which resembles many grasses in the region.

Notes:— Phyllanthus graminoides is described here and placed in Phyllanthus sect. Choretroides , a section of phyllocladiferous species recognized in Brazil. This placement is due to its morphological characteristics, which are similar to those of other species in this section, including P. choretroides , the type species of P. sect. Choretroides . However, it should be noted that this section, as currently defined, is not monophyletic ( Bouman et al. 2021, Orlandini et al. 2023), and further adjustments are needed for its redefinition.

The new species can be recognized by its subshrub habit, with thin and delicate, ascending phylloclades, which, together, resemble some species of grass. The leaves of the species are persistent, usually associated with both inflorescences, with staminate and pistillate flowers with 5 sepals. It is similar to other species with cylindrical phylloclades, such as P. goianensis , P. chapadensis , and P. choretroides . However, it is distinguished from P. goianensis by presenting plants over 1 m in height, linear stipules with an entire margin, and segments of the disk joined to the sepals (vs. plants up to 0.3 m in height, wide-triangular stipules with an entire margin, and lacerated segments of the disk not united to the sepals).

It is distinguished from P. chapadensis by having linear stipules with an entire margin, as well as staminate flowers with 5 sepals (vs. triangular stipules with a lacerated margin, in addition to staminate flowers with 6 sepals). It is distinguished from P. choretroides by presenting plants over 1 m in height, stipules with an entire margin, and 3 stamens with anthers united by the connective (vs. plants less than 1 m in height, stipules with a denticulate margin, and 2 stamens with anthers not united by the connective). Still in relation to the plant habit, P. graminoides has erect phylloclades arranged in a single direction (orthotropic), whereas P. chapadensis has phylloclades that are more spaced and occasionally form a zigzag pattern, mixing both orthotropic and plagiotropic phylloclades.

Figures

FIGURE 1. Phyllanthus graminoides. A. Habit; B. Staminate cymules (detail). C. Staminate Flower. D. Stamens and extrastaminal disk. E. Pistillate flower. F. Gynoecium. G. Fruit. H. Carpophore. I. Seed on ventral (right) and lateral (left) view. Illustrations by Klei Sousa. A–I: J.A. Lombardi et al. 9141 (HRCB 57155).

FIGURE 3. Distribution map of P. chapadensis, P. choretroides, P. goianensis, and P. graminoides.