Phyllanthus eremitus Funez & Hassemer, 2017

Funez, Luís Adriano & Hassemer, Gustavo, 2017, Phyllanthus eremitus (Phyllanthaceae), a narrowly endemic new species from Santa Catarina, southern Brazil, and lectotypification and range extension of P. hyssopifolioides, Phytotaxa 319 (2), pp. 149-158 : 150-156

Phyllanthus eremitus Funez & Hassemer , sp. nov. ( Figs. 1–2).

Type: — BRAZIL. SANTA CATARINA: Rodeio: Eremitério Frei Egídio, 24 September 2016, L. A. Funez, K. Kemmelmeir, M. N. Marascalchi & F. Bittencourt 5534 (holotype FURB).

Diagnosis: —Differs from Phyllanthus acutifolius by leaves with apex acute to acuminate vs. apex acute to obtuse in P. eremitus ; stipules 2–5 mm vs. 0.5–1 mm in P. eremitus ; reddish flowers and fruits in P. acutifolius vs. green in P. eremitus .

Description: —Subshrubs monoecious, 0.3–0.7 m tall; stems cylindrical, the distal parts slightly flattened, glabrous, without phyllanthoid branching, reddish-coloured in young parts. Leaves distichous, chartaceous, strongly discoloured, (3.0)–7.0–20.0 × (3.0)–7.0–14.0 mm, oval, apex acute to obtuse, margin slightly revolute; base symmetrical, acute to obtuse, adaxially green to reddish-green, especially in young leaves, abaxially strongly reddish-green, glabrous on both sides; venation brochidodromous, adaxially inconspicuous, except on the main vein, abaxially strongly impressed; petioles 0.8–1.0 mm long, glabrous; stipules 0.5–1.0 mm long, lanceolate, glabrous. Cymes biflorous, composed of one staminate and one pistillate flower each; bracts 0.5–1.0 mm long, lanceolate. Staminate flowers 2.5–3.0 mm; pedicel 2.5–5.0 mm long. sepals 5, 1.0– 1.5 mm long, oval, membranaceous, yellowish-green; stamens 3, filaments free, anthers with vertical dehiscence; disk 5–lobed. Pistillate flowers 4.0– 4.6 mm: pedicel 4.5–5.0 mm; sepals 5, 2.0–2.3 × 1.2–1.8 mm., elliptic to oval, membranaceous, greenish with hyaline margins; ovary 0.5–0.7 mm long, styles 3, bifid to half of their length; disk entire. Capsules glabrous, smooth, fruiting pedicel 4.5–5.5 mm. Seeds dark brown with 5–6 vertical ribs of darker points, 1.0 × 0.5 mm.

Etymology: —The epithet is a reference to the type locality, Eremitério Frei Egídio, and also to the habitat of this species, arenitic rocky caves.

Distribution: —Endemic to a very narrow area of less than 10 m ², located on a single mountain, in Rodeio municipality ( Fig. 3 ).

Habitat: — Phyllanthus eremitus occurs in the understorey of Atlantic rainforest, in a very specific type of habitat: a cave-like environment, between ever humid arenitic rock outcrops shale rocks, growing on soil constantly humid by the continuous splashing of water, resulting in fog condensation. This specific habitat was found in ca. 800 m asl. ( Fig. 4 ).

Conservation status: —Critically endangered (CR–B2a,b[iii]). This species has an area of occupancy (AOO) of less than 10 m ².

Notes: — Phyllanthus eremitus is slightly similar in characters of floral morphology with P. niruri Linné (1753: 981) , the most common species of Phyllanthus in southern Brazil, due to the pistillate and staminate flowers with 5 sepals, and staminate flowers with 3, completely free stamens. However, the new species can be readily differentiated by the chartaceous leaves with revolute margins vs. membranaceous leaves with flat margins in P.niruri ; woody stems vs. non-woody in P. niruri ; and the symmetric, acute to obtuse leaf base vs. asymmetric to cordate in P. niruri .

Phyllanthus glaziovii Müller (1873: 41) , which occurs in Paraná state, is similar, but differs by the plant size, 0.5–2.0 m tall vs. 0.05–0.70 m tall in P. eremitus . The leaves of P. glaziovii are also larger (15–39 × 5–16 mm) vs. (3.0)–7.0–20.0 × (3.0)–7.0–14.0 mm in P. eremitus , and apically acuminate vs. acute to obtuse in P. eremitus .

Phyllanthus acutifolius Poir. ex Sprengel (1826: 21) , endemic to high elevation grasslands (1,100 –1,200 m) in Serra da Mantiqueira, between Minas Gerais, Rio de Janeiro and São Paulo states, is the species probably most similar to P. eremitus . In addition to the different habitats and geographic disjunction, this species can be differentiated from P. eremitus by the leaf size and shape: 8–23 × 5–12 mm, acute to acuminate vs. (3.0)–7.0–20.0 × (3.0)–7.0–14.0 mm, acute to obtuse in P. eremitus . The flowers and fruits are reddish in P. acutifolius vs. greenish in P. eremitus , and stipules are larger in P. acutifolius , 2–5 mm vs. 0.5–1 mm in P. eremitus .

Although we actively searched in neighbouring similar rock outcrops for other populations of P. eremitus , we were unable to find any. We believe that this species is very restricted in relation to its environmental requirements, such as the necessity of shade and of arenitic, humid substrate. Furthermore, the new species is autochorous by the explosive dehiscence of its fruits, as also in most of other species in this genus, which release the seeds generally few metres from the parental plant. We believe that low viability of the seeds is most probably not a problem for P. eremitus , because we were able to observe a relatively large number of seedlings during field work in the type locality.

The area of occurrence of P. eremitus is a very steep terrain, which is prohibitive to building and agriculture in general. In contrast, the surrounding areas were largely converted into silvicultural plantations, which threaten with extinction any narrowly endemic species in the area due to habitat loss. However, the most critical threat to the survival of P. eremitus is the utilisation of the type locality as camping site by tourists and poachers, because of the natural shelter provided by the arenitic cave-like rock outcrops. We have observed that parts of the type locality had been recently cleaned of plants, including of P. eremitus , and there were signs of fires all around the place ( Fig. 5 ).

All things stated, we conclude that P. eremitus is remarkably different from all other species of Phyllanthus that occur in Santa Catarina and Brazil. Further studies are necessary to reveal the phylogenetic affinities of the new species, and conservation actions are urgently needed to prevent its extinction.

Additional material examined (paratype): — BRAZIL. SANTA CATARINA: Rodeio: Eremitério, 24 January 2017, L. A. Funez & G. Hassemer 5772 ( FURB).

Figures

FIGURE 3. Distribution map of Phyllanthus eremitus (green star) and the first records of P. hyssopifolioides (orange dots) in Santa Catarina, southern Brazil.

FIGURE 4. Habitat of Phyllanthus eremitus.

FIGURE 5. Destruction of the habitat of Phyllanthus eremitus. A. Removed plants. B. Garbage and evidence of fire.