Trixis salina Saavedra & M.Monge, 2020

Monge, Marcelo & Saavedra, Mariana Machado, 2020, A new species of Trixis (Nassauvieae, Asteraceae) from the Center of Plant Diversity of Cabo Frio, Brazil, Phytotaxa 442 (3), pp. 205-214 : 206-212

Trixis salina Saavedra & M.Monge , sp. nov. ( Figs. 1–4 )

Type:— BRAZIL. Rio de Janeiro: Armação dos Búzios, Foca’s Beach, on rocks, near breakwater, 08.10.2016, M. Monge et al. 3349 (holotype: HUFU!; isotypes: UEC195358 !, S!, INPA, MO) .

Shrub, up to 40 cm, succulent, or slightly succulent. Branches pendent, sometimes tangle, cylindrical, striate, wingless, sparsely sericeous, or sericeous, long-stalked glandular trichomes, whitish, glabrescent, apex and lateral buds densely sericeous, or velutinous, whitish. Leaves alternate, persistent, petiolate, petiole (2)6–9(15) mm long, auriculate or not, lamina (2.5)3–10 × (1.2)1.6–3.2(3.7) cm, elliptic, or broadly elliptic, or rarely spathulate, or obcymbiform, base attenuate, margins flat or revolute, rolled, apex acute, or mucronulate, or rarely squarrose, discolor; abaxial surface sericeous, or sparsely sericeous, or velutinous, or in tufts of villose trichomes, long-stalked glandular trichomes, stomata present; adaxial surface strigose, with long hairs, long-stalked glandular trichomes, stomata absent; venation eucamptodromous, prominent abaxially, flat adaxially. Inflorescence apical and axillary, capitula isolated or in helicoid cymes. Capitula long or short pedunculate, peduncle 2–10(17) mm long, sub-involucral bracts 7–13(19) mm long, 1–3, leafy; involucre campanulate, 7–11 mm long, 3 series, 19–20 bracts, green; outer series, bracts 4.3– 6.5 × 1.7–1.8 mm, elliptic, or obovate, or oblanceolate, or spathulate, margins ciliate, apex acute, surface sericeous, long flagellate-septate trichomes, glandular long-stalked trichomes; 1–2 inner series, bracts 7–10(12) × 2–3.2 mm, obovate, or oblanceolate, margins ciliate, apex acute, surface sericeous, long flagellate-septate trichomes, glandular long-stalked trichomes. Receptacle plane, pilose. Flowers ca. 21–22, isomorphic, bisexual, corolla bilabiate, 9–11 mm long, yellow, or whitish, tube 5–6 mm long, inner surface striate, pubescent, flagellate-septate trichomes, inner lobes free, 2-toothed, 3.5–4 mm long, apically pubescent, flagellate-septate trichomes, outer lobes fused, 3-toothed, limb 4–6 mm long, apically pubescent, flagellate-septate trichomes, glabrescent; filament 1.5 mm long, anther 5–6 mm long, calcarate, calcar 1.5–1.8 mm long, smooth, apical appendage 1.5 mm long, elliptic, glabrous, green (young) or yellow (developed); basal stylar node present, rounded, style branches 6.5 mm long, apex truncate, penicellate, with a crown of trichomes, branches 1–1.5 mm long. Cypselae cylindric or fusiform, 7–10 mm long, apically constrict, long-stalked glandular trichomes, pappus 5–7(9) mm long, bristles, cylindric, barbellate, cream, pale, deciduous. Pollen grains prolate, verrucose.

Aditional Specimens Examined (Paratypes):— BRAZIL. Rio de Janeiro: Armação dos Búzios, Foca’s beach, on rocks, near breakwater, 8.10.2016, M. Monge et al. 3349 ( UEC!, S!) ; estrada marginal, Ferradura’s beach restinga, 16.01.2018, I. G. Costa 964 ( HUFU!) ; Ferradura’s beach, rocky coast facing the sea, near the trail end, right side of the beach, 26.11.2018, M. Monge & D. P. Volet 3465 ( HUFU) ; idem, between restinga and the rocky coast, coast trail on the right side of the beach, 26.XI.2018, M. Monge & D. P. Volet 3471 ( HUFU, UEC) ; Brava’s beach restinga, 11.01.1979, G. Martinelli 5602 ( RB199417 !) ; José Gonçalves Beach restinga, 25.06.1999, D. Fernandes 237 ( RB340307 !). Arraial do Cabo, Pontal do Atalaia , 23.03.2014, M. Monge et al. 2749 ( UEC!) ; idem, 22.08.2016, M. Monge & B. B. Z. Vigna 3283 ( UEC) ; ibidem, 22º 58’ 53” S, 42º 01’ 41” W, 10.08.2010, M. M. Saavedra & C. N. Fraga 1034 ( RB499883 !, HUFU79308 !, K, US) ; Prainhas do Atalaia Beach, rocky uprooting between both beaches, near the water spray zone, 15.09.2019, M. Monge & B. B. Z. Vigna 3800 ( HUFU). Cabo Frio, Peró’s Beach restinga, 15.09.1968, D. Sucre 3659 ( RB142114 !, S, MBM, SPF) .

Distribution, Ecology, and Conservation Status:— Trixis salina is known from shrubby and herbaceous restinga vegetation at the Center of Plant Diversity of Cabo Frio (CPDCF) in Rio de Janeiro. It was found at Foca’s, José Gonçalves, and Ferradura’s beaches in Armação dos Búzios, Pontal do Atalaia and Prainhas do Atalaia beaches in Arraial do Cabo, also from Peró’s beach in Cabo Frio. It occurs in well conserved environments with rocky ravines, gneissic or granitic, with shrubby restinga, in the spray zone near the sea in rocky shores between cracks and ravines, or in herbaceous rocky restinga, with shallow soils. Six populations are known, with 70 adult individuals. These populations occur in an environment threatened by the removal of vegetation for real estate development to build summer houses, as reported by local NGOs ( Projeto Colabora 2017), and unsupervised tourism in trails. According to the preliminary conservation assessment using the GEOCat tool ( Bachman et al. 2011), Trixis salina has EOO 132,353 km 2 and AOO 16 km 2, leading to the status of endangered (EN). Thus, Trixis salina is another threatened species of CPDCB.Additionally, climate change affects life on earth and one of the first environments to be affected is the coastal vegetation, due to the 0.5–2 m sea level rise until the end of this century ( Kulp & Strauss 2019), possibly flooding the current locations where populations of Trixis salina occur.

Phenology:—Flowering and fruiting the entire year, especially in populations in wetter environments, near the spray zone at beaches.

Etymology:— Trixis salina is named due to the salty water spray zone near the breakwater, where most populations occur.

Morphology & Putative Adaptations: —Restinga is a harsh environment with several environmental filters, often limiting the species survival, such as desiccation, salinity, oligotrophy, burial, flooding, solar radiation, and high temperatures ( Crawford 2008). Furthermore, the climate at CPDCF is warm and arid, with an annual temperature 25ºC, average precipitation 800 mm /yr, and up to five months of drought ( Dantas et al. 2009). Plants that occur in restinga have morphological and physiological adaptations to these limiting factors. Trixis salina has some morphological traits that may be adaptations to this harsh environment and we found some morphological differences associated to environmental conditions, because some populations are found near the water spray zone, which increases water availability, especially during the dry season, besides, plants located far from the tide lack this additional water source.

One trait is the slightly succulent branches and leaves, which is due to a strong water control, avoiding desiccation during the dry season. We observed differences in populations located 250 m far from the tide compared to populations near the tide. During the wet season, all populations are slightly succulent. Another possible adaptation to the dry and warm climate is the ability to roll up leaves laterally ( Navarro et al. 2006). This strategy might reduce the photosynthetic leaf area, which also reduces water loss during unfavorable conditions. Additionally, it also has the potential to create a wetter microclimate on the rolled leaves, enabling photosynthesis with low water loss (Redmann 1985). On the populations far from the shores showed rolled leaves during the dry season and obcymbiform leaves during the wet season. Populations there are near the shores during the entire year have obcymbiform leaves. Another putative adaptation to dryer habitats is the persistence of dead leaves on the branches, which help to protect the lateral and apical buds during the dry season until the next phase of leaf production ( Damascos et al. 2008, Lambrinos et al. 2006).

From the morphological viewpoint, leaves with a small peduncle have more conspicuous auricule in the petiole attachment on the branches. In general, long petiolate leaves do not have auricule besides the petiole insertion. Furthermore, there is also a variation of leaf sizes, as some plants have larger, broader, and thinner leaves, while others have smaller, narrower, and slightly thicker leaves. Some plants were collected with both types of leaves. We hypothesize that these variations on leaves are related to water availability during the period of producing new leaves.

Taxonomy: — Trixis salina differs from the other Brazilian species of the genus due to the shrubby habit, slightly succulent branches, at least during the wet season, with sparsely sericeous, or sericeous trichomes, with apical and lateral buds densely sericeous, or velutinous, leaves with blades (2.5)3–10 × (1.2)1.6–3.2(3.7) cm, elliptic, or broadly elliptic, or rarely spathulate shape, rolled margins, with acute, or mucronulate, or rarely squarrose apices, revolute, and discolor blades. Trichomes on abaxial surface are sericeous, or sparsely sericeous, or velutinous or in tufts of villose trichomes, long-stalked glandular trichomes. The adaxial surface is strigose, with long hairs, and long-stalked glandular trichomes. The capitula are isolated or in helicoid cymes, the involucre is campanulate, with 7–11 mm long, composed by 3 series of involucral bracts (19–20), with two types of trichomes, long flagellate-septate trichomes, and glandular long-stalked trichomes.

Trixis salina resembles T. antimenorrhoea (Schrank) Mart. ex Baker (1884) due to the shrubby habit, papyraceous leaves, yellow, and white flowers, but T. salina differs from T. antimenorrhoea by the erect habit (vs. climbing), slightly succulent branches (vs. non succulent branches), apical and lateral buds densely sericeous or velutinous (vs. puberulous or strigose), leaves elliptic, or broadly elliptic, or rarely spathulate (vs. ovate, or ovate-lanceolate, or elliptic), leaf apex acute, or mucronulate, or rarely squarrose (vs. acuminate or cirrhous), abaxial surface sericeous, or sparsely sericeous, or velutinous or in tufts of villose trichomes, long-stalked glandular trichomes (vs. tomentose or villose, rounded glandular trichomes), involucre with 3 series of bracts (vs. 2 series), outer involucral bracts broader, elliptic, or obovate, or oblanceolate, or spathulate (vs. linear-lanceolate), and more flowers per head, 20–21 (vs. 10– 11).

Previously, in the state of Rio de Janeiro six species of the genus were recorded ( Esteves 2014), which are distinguished by the following identification key with the addition of Trixis salina .

Figures

FIGURE 1. Trixis salina. A. Reproductive branch. B. Detail of the abaxial side of the leaf. C. Detail of the capitulum. D. Detail of the receptaculum. E. Detail of the outer involucral bract. F. Detail of the intermediate involucral bract. G. Detail of the inner involucral bract. H. Flower. I. Detail of an open corolla with androecium and gynoecium. J. Detail of an open corolla. K. Detail of androecium and gynoecium. L. Anthers. M. Style. N. Cypsela. Drawing by Maria Alice Rezende.

FIGURE 2. Distribution map of Trixis salina in Rio de Janeiro state, Brazil.

FIGURE 3. Trixis salina. A. Reproductive branch. B. Shrubby restinga and habit. C. Detail of the capitula. D. Lateral view of the capitula. E. Habit. F. Detail of vegetative structures. G. View of the ravine of the Foca’s Beach. H. Rocky and sandy environment of the Prainha Beach populations of. I. Ravine environment. (Images A, G G.H.Shimizu; B–D C.N.Fraga; E, F, H, I M.Monge).

FIGURE 4. Microcharacters of Trixis salina from scanning electron micrography. A. Sericeous and glandular trichomes with neck on branches. B. Young leaf on abaxial side with dense sericeous trichomes. C. Developed leaf on abaxial side with sericeous trichomes. D. Developed leaf on adaxial side with long strigose and long-stalked glandular trichomes. E. Detail of long-stalked glandular trichome. F. Detail of long flagellate-septate trichomes. G. Detail of pubescent corolla lobe. H. Detail of the inner side of the corolla tube, with flagellate-septate trichomes and striate surface. I. Pollen grains. J. Basal anther appendage. K. Details of truncate and pennicelate branches of the style. L. Detail of the stylopodium base.