Commelina catharinensis Hassemer, J.P.R.Ferreira, Funez & J.D.Medeiros, 2016

Hassemer, Gustavo, Ferreira, João Paulo Ramos, Funez, Luís Adriano & Medeiros, João De Deus, 2016, Commelina catharinensis (Commelinaceae): a narrow endemic and endangered new species from Santa Catarina, southern Brazil, Phytotaxa 246 (1), pp. 49-60 : 50-56

Commelina catharinensis Hassemer, J.P.R.Ferreira, Funez & J.D.Medeiros , sp. nov.

Type:— BRAZIL. Santa Catarina : Palhoça: na beira de trilha em restinga arbustiva na Praia do Sonho , 27°49’29.88”S 48°35’27.00”W, 3 m, 16 December 2015, G. Hassemer, J.D. Medeiros & J.P.R. Ferreira 855 (holotype FURB; isotypes FT, HURB, RB). ( Figures 1–3 )

Additional material examined (paratypes): — BRAZIL. Santa Catarina : Laguna : restinga, 16 October 1971, G.G. Hatschbach & C. Kocziki 27524 ( MBM 21220 ) ; Caputera , dunas fixas, 12 February 1978, G.G. Hatschbach & E.M. Zardini 40976 ( MBM 58488 ) ; Lagoa do Imaruí , campo de restinga, 3–5 m, 3 October 1988, G.G. Hatschbach et al. 52358 ( MBM 135187 ) ; Praia do Sol , beira da restinga, 17 March 2005, G.G. Hatschbach et al. 79225 (C, FT, MBM 304712 ) ; Palhoça: Praia do Sonho , 27°49’29.59”S 48°35’26.68”W, 3 m, 29 November 2014, M.R. Stefani s.n. ( FLOR) ; Praia do Sonho , restinga, 27°49’29.88”S 48°35’27.00”W, 3 m, 24 December 2014, J.D. Medeiros s.n. ( FLOR 55014 ) .

Diagnosis: —Leaf blades with vinaceous margins. Auricles absent. Developed petals two, cream-yellowish. Lateral stamens 2, with yellow anthers and fillets. Fruit a dehiscent capsule, light brown, with asymmetric brown seeds.

Description: —Herbaceous plants, 20–39 cm tall. Stems with 10–11 nodes, radicant in the lower nodes, erect to prostrate, usually non-branching, 0.6–2.0 mm wide, dark green with vinaceous longitudinal streaks, sparsely pilose with very short trichomes (ca. 0.1–0.4 mm long), especially close to the nodes. Leaf blades 2.8–7.0 × 0.4–0.8 cm, sessile, linear-lanceolate, glabrous or abaxially sparsely pilose with very short trichomes, base cuneate, auricles absent, apex acuminate, margins entire with characteristically violet colour; sheath 0.7–1.5 × 0.3–0.6 cm, characteristically vinaceous, especially along the longitudinal streaks, pilose with very short trichomes, but with large multicellular trichomes (1.0–3.0 mm long) concentrated at the apex of the lateral margins. Spathe 1.3–1.5 × 0.9–1.0 cm (folded), 11–13-nervated, cordate, apex acute, isolated or grouped into two in the stem apex, shortly pilose, conjunctly with large multicellular trichomes (1.0–3.0 mm long) near the base, basal margins connate up to half its length, smooth, glabrous; spathe petiolate, petiole 1.5–4.0 mm length. Inflorescence with 2–4 flowers, pedunculate, peduncle erect 0.4–0.8 cm long, glabrous; pedicellate flowers, pedicels 4.0 mm long, glabrous. Sepals 3; the dorsal one 2.0–2.5 × 1.1– 1.5 mm, ovate, apex acute, glabrous, the two ventral ones 3.7–4.5 × 2.0–3.0 mm, fully connected or up to 2/3 of their length, cymbiform, apex obtuse, smooth margin, glabrous. Petals 3; two developed dorsal petals 9.0–13.0 × 5.0–12.0 mm, unguiculate, reniform, apex rounded, cream-yellowish; one reduced ventral petal 0.8–1.0 mm, linear. Stamens 3, ventrally arranged; two lateral stamens, yellow, with anthers 1.1–1.5 × 0.7–1.0 mm, elliptical, longitudinally dehiscent, dorsifixed, fillets 5.5–7.3 mm long; central stamen with anther 1.5–2.1 × 1.2 mm, sagittiform, bent at the apex, longitudinally dehiscent, basifixed, yellow, fillets 5.0 mm long. Staminodes 3, dorsally arranged, antheroid 1.5–1.8 × 1.2–1.5 mm, 4-lobed, yellow, fillets 3.0– 4.5 mm long. Stigma capitated, stiletto 6.0–9.0 mm long. Ovary 0.8–1.2 × 0.6–1.0 mm, globose, shortly pilose, tricarpellate, trilocular, loci uniovulated, placentation axial. Capsule dehiscent, septicidal, 3.0–4.2 × 4.0– 4.4 mm, globular, light brown, glabrous. Seeds 2.0–4.0 × 1.5–2.2 mm, asymmetric, ellipsoid, pilose, brown; ventral face slightly concave, with a central depression; dorsal face slightly convex, with a whitish longitudinal groove.

Phenology: —Confirmed flowering and fruiting: October–March. This information is based on our field observations, and also on the revision of herbarium materials.

Distribution: —Known from only two very restricted areas of coastal restinga in eastern SC ( Figure 4 ), forming two populations: one in Praia do Sonho, Palhoça municipality (the type locality), and another around Praia do Sol, Laguna municipality.

Habitat: —Open areas amidst shrubby “restingas litorâneas” (marine-influenced vegetation on sandy soil) ( Figure 5 ).

Conservation status: —Endangered (EN–B2a,b[i,ii,iii,iv,v]). This species has a dramatically narrow area of occupancy (AoO), of less than 8 km 2. Intense sampling efforts in nearby areas environmentally similar have failed to find any other populations. The only two known populations are under threat of legal and illegal urban advance. Preventing the illegal occupation of these areas is difficult, because such occupations are largely tolerated by Brazilian authorities and the general public, despite causing extensive, ever-increasing and most often irreversible environmental damage.

In January 2016, about two weeks after the initial submission of this manuscript, an illegal occupation attempt took place about 50 metres from the type locality. The vegetation in the area was completely destroyed ( Figure 5B ). Fortunately, this environmental crime was deterred in time by the local environmental administration, and the population of C. catharinensis in Praia do Sonho survived.

In addition to all human threats, the habitat of C. catharinensis is also being invaded by the highly-invasive pine species Pinus elliottii Engelmann (1880: 186–190 , t. 1–3) ( Pinaceae ) ( Figure 5A ), which is a serious threat to all narrow endemic herbaceous plant species of the coastal restingas in South America. Given the current threats to the Praia do Sonho population, we believe that C. catharinensis will become locally extinct at its type locality in a decade or so if no effective conservation actions are promptly taken.

Observations: —The cream-yellowish petals of C. catharinensis is by far the most striking and unique feature of this species, as no other species in South America present this character. The new species is somewhat similar to C. rufipes Seubert (1855: 265–266) , which nevertheless has white flowers (instead of cream-yellowish) and whitishsilvery indehiscent fruits (instead of light brown dehiscent fruits). All other species of Commelina in South America have white, blue, or purple petals. Another character that seems unique to C. catharinensis is the very distinctive purple border of the lamina of its leaves. Among the other species of Commelina in South America, C. erecta is the morphologically most similar to C. catharinensis . However, these two species, and also C. rufipes , can be differentiated by a considerable group of characters (see Table 1, the identification key below, and also Figure 6 ).

No other species of Commelina were found occurring in strict sympatry with C. catharinensis . However, we found populations of C. erecta in other areas of restinga, close to the type locality of C. catharinensis in Praia do Sonho ( Figure 6A ). We have not found any evidence of hybridisation between the two species, nor any intermediates.

The discovery of a new plant species in the coastal restingas close to Florianópolis, the capital city of SC, is a very noteworthy event, because the restingas in SC, especially around Florianópolis, have already been heavily-sampled (especially by botanists of HBR and MBM, and later also FLOR and FURB herbaria) and can be considered to be well known ( Falkenberg 1999).

Figures

FIGURE 1. Illustrations of Commelina catharinensis. A. Habit. B. Spathe. C. Dorsal sepal. D. Ventral sepals. E. Developed dorsal petal. F. Reduced ventral petal. G. Lateral stamen. H. Central stamen. I. Staminode. J. Gynoecium. K. Fruit. L. Seed, ventral face. M. Seed, dorsal face. From J.D. Medeiros s.n. (FLOR 55014); illustrations by Diogo Chicatto.

FIGURE 2. Photographs of Commelina catharinensis. A. Habit. B. Detail of leaves and spathe. C. Detail of flower. All photographs by J.D. Medeiros.

FIGURE 3. Photographs of Commelina catharinensis. A. Spathe containing fruits. B. Detail of mature fruit. C. Detail of seed, dorsal face. D. Detail of seed, ventral face. Photographs by J.D. Medeiros (A) and J.P.R. Ferreira (B, C, D).

FIGURE 4. Distribution map of Commelina catharinensis.

FIGURE 5. Habitat of Commelina catharinensis and some of the current threats to the survival of this species.A. Type locality at Praia do Sonho in 2015. B. Damage caused by a very recent illegal occupation attempt of Praia do Sonho in 2016, about 50 metres from the only known population of C. catharinensis in this locality. Photographs by J.D. Medeiros.

FIGURE 6. Photographs of blue- and white-flowered plants of Commelina erecta at Praia do Sonho (the type locality of C. catharinensis) (A) and Xanxerê, western Santa Catarina state, Brazil (B). Photograph by J.D. Medeiros (A) and L.A. Funez (B).