Syagrus harenae B. F. Sant'Anna-Santos 2025, sp. nov.
Year: 2025
Type: other
Abstract: Syagrus harenae B. F. Sant’Anna-Santos sp. nov. Figs 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, Tables 1, 2 Type. BRAZIL – Minas Gerais • Itamarandiba, Vilarejo de Penha da França; 18°2’44.76”S, 43°4’45.02”W; 1000 m; 15 Feb. 2024; fl., fr.; Sant’Anna-Santos & Francino 406; holotype: DIAM; isotypes: UPCB, IBGE, HCF. Diagnosis. Syagrus harenae is similar to S. glaucescens Glaz. ex Beccari, from which it differs by lax pinnae on the leaf rachis (vs congested pinnae), apical pinnae size (8–12 × 0.2–0.4 vs 1.5–6 × 0.2–1.0), pinnae with symmetrical tip (vs asymmetrical); base of the stem not-angular (vs angular), brownish indumentum where pinnae are inserted on the lower leaf rachis (vs glabrous); prostrated stem (vs erect); sheathing leaf base length (10–28 cm vs 42–52 cm), lax sheathing leaf base (vs congested); inflorescence strongly pendulous (vs erect ou slightly pendulous); peduncle with scattered thin indumentum (vs glabrous); petal tips imbricate (vs valvate); pistil with whitish indumentum on lower 1 / 3 (vs glabrous), inconspicuous staminodial ring (vs conspicuous staminodal ring); fruit yellowish-orange when mature (vs brownish). Description. Small to moderate-sized palm, solitary, 110–160 (– 250) cm tall. Stem 40–110 (– 140) × 15–25 cm, prostrate, with persistent leaf bases arranged in rows with indistinct internodes near the crown, non-angular stem base. Leaves pinnate number 8–15; sheathing leaf base ca 10–28 cm long; pseudopetiole 15–37 cm long; petiole 9–27 × 0.5–1.6 cm and 0.2–0.7 cm thick, rachis 95–167 cm long; abaxial side of petiole and rachis with brownish tomentum; pinnae medium to dark-green, discolourous, abaxial surface glaucous, linear, rigid-coriaceous with apex more or less symmetrical and long tapering, pinnae numbering 63–79 pairs, in clusters of 2–5, lax on leaf rachis, inserted in divergent planes over the rachis; pinnae with inconspicuous ramenta scales along the abaxial midrib (near the rachis) on young leaves; basal pinnae 27–36 × 0.4–0.6 cm, middle pinnae 17.5–30.5 × 1.7–2.3 cm, apical pinnae 8–12 × 0.2–0.4 cm. Inflorescences pendulous, spirally branched, prophyll 11–16 (– 26) × 1.3–2.5 cm; peduncular bract 56–72 cm long, inflated portion 25–31 × 5.2–7.5 cm, including a 1.0– 1.4 cm beak, 6.4–8.5 cm perimeter, 2–3 mm thick, woody, sulcate, exterior glabrous; peduncle 30–41.5 cm long, 8–10 × 4–7 mm wide, with brownish scarce indumentum; inflorescence axis 19.5–24 cm long; rachis 1.5–13.3 cm long; rachillae 3–15, glabrous, yellow, 8.5–20 cm long at the apex, 12–17 cm long at the base; flowers arranged in triads, tetrads (with two central pistillate flowers, each flanked by a staminate flower) or pentads (with three central pistillate flowers flanked by two staminate flowers), staminate flowers with three sepals and three petals, and pistillate flowers with three sepals and three petals, two sepals and four petals, three sepals and four petals. Staminate flowers 9–10 × 4–5 mm at the apex, 11.5–14 × 4–6 mm at the base, those at the apex sessile, sometimes pedicellate, pedicels 1–4 mm long, yellowish-orange, sepals 1.5–3.5 × 1.5–2.5 mm, glabrous, triangular, no visible nerves, keeled, connate at the base, petals 8–10 × 2.5–4.0 mm at the apex, 9–19 × 3.5–4.5 mm at the base, with acute tips, slightly nerved; ovate-triangular, valvate, stamens 5–7 mm long; anthers 4–7 mm long, basally sagittate; filaments 2–3 mm long, free at the base, dorsifixed at the base (basifixed); pistillode trifid, ca 0.8–1.0 mm. Pistillate flowers elongate-pyramidal, 13–17 × 6–7 mm, orangish-yellow when immature and green when mature, glabrous; sepals 13–16 × 5–7 mm, orangish-yellow when immature and green when mature, without visible venation, triangular, imbricate; petals 10–13.5 × 3–5 mm, orangish-yellow when immature and green when mature, imbricate, triangular; pistil 6–8 × 3–4 mm, with whitish indumentum from the base of the pistil to nearly the base of the stigmas, stigmas 3– 3 mm long, glabrous; inconspicuous staminodial ring rarely present, less than 0.5 mm in height, staminodes arranged in pairs or isolated (sometimes with anthers), six in number, ca 1.0– 1.8 mm in height. Fruits ellipsoid, 2.1–3.0 × 1.6–2.0 cm, orange when mature, scaly lepidote tomentum, epicarp less than 0.5 mm thick, mesocarp less than 0.5 mm thick, succulent, and fibrous; endocarp 1.8–2.0 × 1.2–1.9 cm, 2–3 mm thick on the sides, 4–5 mm thick on the tips, trivittate interior. Seeds more or less ellipsoid, endosperm homogeneous. Germination remote tubular. Distribution. The type population of Syagrus harenae was found in the village of Penha de França, in the Serra do Ambrósio mountain (Fig. 1 A – E). Habitat. The Serra do Ambrósio mountain is characterised by forest formations at its base, which end abruptly at an altitude of around 900 meters, giving way to open vegetation types, such as the carrascos (Meguro et al. 1994). The steepness of the slope, the thickness of the colluvial deposits and the texture of the sandy soils are the main factors determining the vegetation type found on these slopes (see Meguro et al. 1994; Pirani et al. 1994). In this transitional environment, the coarse white sand deposited by rainwater drainage derives from quartzite rocks (Meguro et al. 1994; CODEMIG 2012; Costa et al. 2016) and is the substrate of the area where the new species was discovered. In areas with a gentle slope and sand deposition, at an altitude range of 800–1200 m, the vegetation is known as carrasco and is characterised by very ramified scrawny bushes, ranging from an open to dense physiognomy (Pirani et al. 1994; Oliveira et al. 2014). The new species is more abundant in the carrasco with dense physiognomy (Figs 3 A, 7 A – B, 8 G, J – K). Costa et al. (2016) state that “ sandy soils are common in the Espinhaço Range, but those in Serra do Ambrósio have a different granulometry ”. The climate of Serra do Ambrósio is Cwb according to the climatic classification of Köppen (1948), attenuated by altitude, with distinct wet and dry seasons, mean annual temperatures of 14.1–23.8 ° C and a mean annual rainfall of 1405 mm (Meguro et al. 1994). However, the air temperature at noon attains 30 ° C with air humidity at 40–50 %, while 2 cm below the sandy soil surface the temperature can reach 40–50 ° C (Meguro et al. 1994). Where the vegetation is denser on the carrasco, the larger shrubs shade the herbaceous and low subshrubby species, and the sandy soil is partially or entirely covered by the leaf litter (Figs 3 A – B, 8 G, J – K). Besides retaining moisture, the leaf litter might reduce the soil temperature and release organic matter, favouring the greater number of S. harenae specimens observed in these places (Figs 3 A – B, 7 A – B, 8 G – H, J – K). The high floristic diversity in the carrasco includes species with large distribution (Pirani et al. 2014), such as Ananas ananassoides (Baker) L. B. Sm. (Fig. 7 C), a common species throughout Brazil (Reflora 2024). Moreover, species characteristic of other mountains in the Espinhaço Range, such as Kielmeyera regalis Saddi. (Figs 3 A, 7 B) and Pilosocereus aurisetus (Werderm.) Byles & G. D. Rowley (Fig. 7 D – E) are also common in the carrascos of Serra do Ambrósio. However, the flora in Serra do Ambrósio is also characterised by the presence of rare species (Pirani et al. 1994; Costa et al. 2018), such as Uebelmannia gummifera (Backeb. & Voll) Buining (Fig. 7 F). The Serra do Ambrósio mountain should be highlighted as an outstanding conservation area for other botanical families, especially Eriocaulaceae (see Oliveira et al. 2014; Costa et al. 2016). To date, endemic species of Eriocaulaceae have been recognised for the Serra do Ambrósio (Pirani et al. 1994; Costa et al. 2016). Ecology. After peduncular bract opening, the orangish-yellow flowers of S. harenae are prominent in the subshrub layer of the denser carrasco (Figs 7 A, 8 A – C, E). The staminate flowers remain orangish-yellow until they fall off (Figs 4 A – H, M, 5 A, 8 A – C, E, G). On the other hand, the pistillate flowers transition from yellow to green over time (Figs 4 A – H, M, 5 A, 8 A – C, E). Soon after the anthesis of the peduncular bract, the flowers are visited by flies (Fig. 8 A), stingless bees (Fig. 8 B – C), and beetles (Fig. 8 D). In S. harenae, the beetles and their larvae intermingle among the flowers, covered in pollen grains (Fig. 8 D – F). Palms are well-known as hotspots for insect abundance and diversity, but so far for Syagrus, the evidence points to pollination both by beetles and bees (Silberbauer-Gottsberger et al. 2013; Núñez-Avellaneda et al. 2015; Guerrero-Olaya and Núñez-Avellaneda 2017; Núñez-Avellaneda and Carreño 2017). According to Medeiros et al. (2019), beetles breed on floral tissues of S. coronata as larvae. Besides pollen, nectar is another floral reward associated with Syagrus (Silberbauer-Gottsberger et al. 2013). In addition, the presence of osmophores in pistillate flowers has already been recorded for the genus (see Sant’Anna-Santos et al. 2023 a). In S. harenae, nectar drops were not observed, a strong sweet odour was released, and the visit of bees to both pistillate and staminate flowers may indicate that they are looking for a resource other than just pollen (Fig. 8 B – C). However, future studies will be necessary to identify which secretory structure is associated with offering rewards to pollinators and verify the presence of osmophores or nectaries in S. harenae. In Syagrus, most species display flowers in shades ranging from green to yellow (see Noblick 2017 a), but the re-greening of flowers after anthesis is rare. This phenomenon has only been documented twice: first in Syagrus coronata (Mart.) Becc. (Medeiros et al. 2019) and now in Syagrus harenae. Flower colour changes after anthesis (e. g. Weiss 1995; Lunau 1996; Nadot and Carrive 2021) due to ageing or pollination, though observed across various plant taxa, are relatively uncommon (Ruxton and Schaefer 2016) and are often seen as sig
Authors: Sant'Anna-Santos, Bruno Francisco, Lopes Pereira Nunes, Elaine, Micheli, Rafael, Maria Teodoro Francino, Dayana
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W6930429652
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