Syagrus amicorum K. Soares & C.A. Guim., 2019

Soares, Kelen Pureza & Guimarães, Carlos Alex Lima, 2019, Syagrus amicorum, a new Arecaceae from Bahia, Brazil, Phytotaxa 387 (2), pp. 158-164 : 159-164

Syagrus amicorum K. Soares & C.A. Guim. , sp. nov. ( Figs. 1 , 2A–L , 3A–D and 4 ).

Type:— BRAZIL, Bahia: Guaratinga, Maitá stream, in Inselberg, 435 m elevation, 24 K 379788 8168867, 16 May 2018, K. P. Soares 67, C. A. Guimarães, J. E. Santos, L. C. Assis, fl. fr. (holotype UESC!, isotype BHZB!, ALCB!, CEPEC!, HDCF!, RB!).

Species morphologice proxima Syagro ruschianae. Facile separata huius marginibus vaginarum et pseudopetiolis fibris rigidis, instar spinae rudimentaris (vs. margines fibris flexibilibus), rhache foliari 100–110 cm longa (vs. 128–200 cm longa), foliolis rigidis, congestis et insertis modo ascendente in rhache (vs. foliola flexibilia et pendula in extremitate, rara distributio in rhache), foliolis partis medianae rhachis 34–38 × 2.2–2.4 cm (vs. 50–53 × 2.4–3.5 cm), facie abaxiali foliolorum dense tomentoso-flocosa supra nervatura principali in primis 3–6 cm insertionis cum rhache (vs. solum praesentia ramenti sparsi in nervatura principali) et numero rhachilarum inflorescentiae 12–20 (vs. 41–75).

Plant small to moderately-sized, up to 3.5 m tall, usually clustered, sometimes solitary, unarmed. Stem 1–2.5 m × 10–14 cm, erect or arching, often with persistent leaf sheath, when they eventually fall, well-marked scars remain on the surface of the stem ( Fig. 1 ). Leaves spirally arranged, slightly arched, 6–10 in the crown; leaf sheath 34–45 × 3.5–7 cm, with fibrous margins, some narrower and remaining as persistent rigid fibers, like rudimentary spines, giving a toothed appearance ( Figs. 2A , 3C ); pseudopetiole 9–20 × 1.5–1.7 cm; petiole absent or nearly so; rachis 100–110 cm long, channeled adaxially and rounded abaxially, adaxial and mainly abaxial side of the petiole and rachis covered by whitish pruinous tomentum; leaflets 55–60 along one side, regularly distributed on the rachis in one plane ( Fig. 2B 1 ), linear, rigid, medium to dark green, slightly paler on the lower surface, transverse veins inconspicuous; several ramenta spreading along the abaxial midvein and a cluster of dense floccose tomentum along the first 3–6 cm where the leaflets are inserted on the rachis ( Figs. 2B2 , 3D ), leaflet apex asymmetrical acute ( Fig. 2C ), basal leaflets 34–42 × 1.4–1.6 cm, middle leaflets 34–38 × 2.2–2.4 cm, apical leaflets 23–28 × 1.1–1.7 cm. Inflorescence interfoliar, paniculate, spirally branched ( Fig. 2D ); prophyll 22–48 × 3.5–4.8 cm; peduncular bract 114–185 cm long, expanded part 60–100 × 4.5–6 cm, 1.5–2 mm thickness and with a 5–6 cm long beak, narrow, woody, sulcate ( Fig. 2E ), exterior with scattered thin indument; peduncle 77–107 × 0.55–1 cm, laterally compressed with whitish waxy indument; inflorescence axis 46–81 cm long; rachis 23–50 × 0.4–1.2 cm; rachillae 12–20, 21–40 cm long at the apex, 29–48 cm long at the middle, and 33–46 cm long at the base. Flowers arranged in triads on the lower portion, being one central pistillate flower flanked by two lateral staminate flowers ( Fig. 2F ), and spirally arranged on the upper portion of the rachilla, yellow or creamwhite in color; staminate flowers 7–8 mm long at the base of the rachilla and 5–8 mm long at the apex of the rachilla ( Fig. 2G ), sepals 1.5–2 × 0.5–1 mm, glabrous with no distinct venation, petals valvate 4.5–6.5 × 1.5–2 mm with acute tips, stamens 6, 3.5–4 mm long, anthers 3.5–4 mm long, filaments 1–1.5 mm long, pistillode 0.5–1 mm long; pistillate flowers rounded to ovoid, 6–9 × 5–7 mm at the base and 5–7 × 4.5–5 mm at the middle part of rachilla ( Fig. 2H ), glabrous, sepals 5–8 × 4.5–6 mm, not keeled, visibly veined, petals 4.5–5.5 × 4–5 mm, glabrous with inconspicuous venation, imbricate almost entirely, valvate tips 1/5 the length of the petal, ca. 1 mm long, gynoecium 2.5–3.3 × 2–2.8 mm, glabrous, stigmas ca. 1 mm long, glabrous. Fruit ovoid to globose, 2.5–3 × 2.4–2.8 cm, yellow to orange when mature, with whitish indument mainly at apex, epicarp less than 1 mm thick, mesocarp fibrous with no juicy pulp, which frequently split at its tip when mature ( Fig. 2I–K ); endocarp ovoid, 2.1–2.5 × 1.8–2.2 cm, 1.5–2 mm thick; seed nearly globose, 1.5–1.9 cm in diameter, endosperm homogeneous ( Fig. 2L ). Germination remote-tubular.

Common name: —licuri.

Etymology: —The specific epithet amicorum means “of friends” in Latin, referring to the spirit of the tour under which the type specimens were collected. The name was suggested by João Eduardo Santos, who discovered this new palm ( Fig. 3B ).

Distribution and habitat: —This species seems to be endemic to southern Bahia in the western portion of the Guaratinga municipality. So far it has been found on the top or on the steep sides of only one inselberg, where about 100 individuals can be found ( Figs. 3A , 4 ). It grows in thin soil with many saxicolous plants such as cacti, bromeliads and other palm species like Syagrus guaratinguensis Noblick (2018: 79) and Syagrus romanzoffiana ( Chamisso 1822: 5) Glassman (1968: 382) , at an elevation of 435 m. The inselberg where this species grows is characterized by rounded, pre-Cambrian granite mountains—outcroppings common to the region, being a part of the Serra do Mar formation. The vegetation that inhabits this type of ecosystem is unique for its high degree of endemism, with plants capable of surviving a high solar radiation index, water stress and lack of substrate.

Conservation Status: —Although this species grows in a non-agricultural area with fine rocky soil, it is native to only one inselberg. However, the entire area where it grows is threatened by fire used for pasture expansion and destruction by livestock, which threatens the species’ ability to regenerate. This area is not under any protection and only one population was found, with ca. 100 individuals. Because of this, the species is classified as Critically Endangered B2ab(i,ii,iii,iv,v), C2a(ii), according to the IUCN criteria.

Phenology: —This palm species appears to flower and bear fruit throughout the year. Inflorescences and ripe fruits were found in May during the type specimen collection.

Uses: —This palm has great ornamental potential with its small to medium size, very attractive dark green coriaceous leaves and is possibly drought resistance. Its endocarps are used locally by children to play marbles.

Taxonomic observations: — Syagrus amicorum is morphologically closely related to S. ruschiana ( Bondar 1941: 45) Glassman (1963: 261) ( Fig. 3E–F ), due to its rock-loving, usually clustering habit, inflorescence with narrow and long peduncular bract, rounded pistillate flowers, ovoid to nearly globose yellow to orange fruit, which usually split at its tips when mature. However S. amicorum clearly differs from S. ruschiana by its leaf sheaths and pseudopetiole margins with toothed fibers, like rudimentary spines (vs. only with flexible fibers in S. ruschiana ), rachis with 100–110 cm long (vs. 128–200 cm long in S. ruschiana ), rigid leaflets, congested on the rachis, inserted in an upward angle (vs. pendulous leaflets, especially at the tips, with a well spaced distribution on the rachis in S. ruschiana ), middle leaflets with 34–38 × 2.2–2.4 cm (vs. 50–53 × 2.4–3.5 cm in S. ruschiana ), with a cluster of dense floccose tomentum on the first 3–6 cm of the abaxial midvein where the leaflets are inserted on the rachis (vs. only a few and sparse ramenta present on the whole abaxial midvein in S. ruschiana ) ( Fig. 3D–E ) and by the number of rachillae in the inflorescence, 12–20 (vs. 41–75 in S. ruschiana ).

The new species can only be found in one inselberg, in the Guaratinga municipality, in the state of Bahia, while S. ruschiana is distributed about 150 km to the South, in the states of Espirito Santo and Minas Gerais. Both species grow in similar soil and climate conditions.

Syagrus amicorum is also similar to Syagrus santosii Soares & Guimarães (2013: 420) due to its leaf morphology with rigid, regularly distributed leaflets on the rachis and inserted in an upward angle, inflorescence with narrow and long peduncular bract, rounded pistillate flowers and by the fruit, which usually split at its apex when mature ( Fig. 3G–H ). However S. amicorum easily differs from S. santosii by its usual cluster habit (vs. always single habit in S. santosii ) ( Figs. 1 , 3H 1 ), by its leaf sheaths and pseudopetiole margins with toothed fibers, like rudimentary spines (vs. well-defined teeths, true spines in S. santosii ) ( Fig. 3C, G ), rachis with 100–110 cm long (vs. 160–194 cm long in S. santosii ), 55–60 leaflets along one side of the rachis (vs. 71–90 leaflets along one side of the rachis in S. santosii ), middle leaflets with 34–38 × 2.2–2.4 cm (vs. 46–54 × 2–3 cm in S. santosii ), with a cluster of dense floccose tomentum on the first 3–6 cm of the abaxial midvein, where the leaflets are inserted on the rachis (vs. only a sparse ramenta present on the whole abaxial midvein in S. santosii ), by the number of rachillae in the inflorescence, 12–20 (vs. 43–62 in S. santosii ), by the fruits, yellow to orange, with 2.5–3 × 2.4–2.8 cm (vs. light yellow or yellowish-green, with 2.9–4.6 × 2.6–3.8 cm in S. santosii ) ( Figs. 2I–K , 3H 2 ), and by endocarp 2.1–2.5 × 1.8–2.2 cm (vs. 2.7–4.2 × 2.4–3 cm in S. santosii ) ( Figs. 2L , 3H 4 ).

Both S. amicorum and S. santosii appear restricted to a single and small area of occurrence in the state of Bahia, but the areas are 90 km apart. At this moment, S. santosii has only been found on the margins of Rio Jequitinhonha, in the Itapepi municipality, where it grows for a distance of 4 km along the southern margin of the river at an elevation of 111–119 m above sea level in sandy clay soils, while S. amicorum has been found on the top or on the steep sides of only one inselberg in the Guaratinga municipality.

Finally, the new species is also similar to Syagrus schizophylla Martius (1826: 119) Glassman (1968: 386) due its inflorescence with narrow and long peduncular bract, rounded pistillate flowers and by the yellow to orange fruit ( Fig. 3I ). However, S. amicorum easily differs from S. schizophylla by usual cluster habit (vs. always single habit in S. schizophylla ) ( Figs. 1 , 3I 1 ), by its leaf sheaths and pseudopetiole margins with toothed fibers, like rudimentary spines (vs. well-defined teeth, a true spine in S. schizophylla ), leaflets with a cluster of dense floccose tomentum on the first 3–6 cm of the abaxial midvein where the leaflets are inserted on the rachis (vs. no ramenta or tomentum present in S. schizophylla ), and by homogeous endosperm (vs. ruminate endosperm in S. schizophylla ) ( Figs. 2L , 3I3 ).

Syagrus amicorum grows in one inselberg, 110 km from the coast, while S. schizophylla grows only in the open coastal restinga, generally in sandy soils or sometimes in lateritic clay soils on the steep hills along the beaches ( Noblick 2017), up to 20 km from the coast.

Figures

FIGURE 1. Syagrus amicorum habit. Drawn by and from image taken by K. Soares.

FIGURE 2. A–L. Syagrus amicorum. A. Leaf sheath with woody fibers like rudimentary spines. B. Leaf blade. B1. Adaxial surface of the apical portion. B2. Abaxial surface of the middle portion showing the dense floccose tomentum where the leaflets are inserted on the rachis. C. Leaflet apex. D. Middle-apical portion of the inflorescence. E. Apical portion of dry peduncular bract. F. Flowers triad at basal portion of the rachilla, a pistillate flower flanked by two lateral staminate flowers. G. Staminate flower. H. Pistillate flower. I. Fruit in lateral view. J. Fruit in top view. K. Mature fruit split at its apex, showing the mesocarp and the endocarp. L. Endocarps, one of them sectioned showing the homogeneous endosperm. Drawn by K. Soares from K. Soares et al. 67.

FIGURE 3. A–D. Syagrus amicorum. A. habitat, where it grows together with the palm species S. guaratinguensis. B. habit with João Eduardo Santos, its discoverer. C. Toothed leaf sheaths. D. Abaxial part of leaf showing the dense floccose tomentum where the leaflets are inserted on the rachis. E–F. Syagrus ruschiana. E. Abaxial part of leaf showing the sparse ramenta on the midveins of its leaflets. F. habit. G–H. Syagrus santosii. G. Leaf sheaths with well-defined teeths (true spines). H. illustration. H1. Habit. H2. Fruit in lateral view. H3. Fruit and endocarp sectioned showing the homogeneous endosperm. H4. Endocarp. I. Syagrus schizophylla illustration. I1. Habit. I2. Fruit in lateral view. I3. Fruit and endocarp sectioned showing the ruminate endosperm. I4. Endocarp. Image and drawn by K. Soares, H from K. Soares et al. 40, I from K. Soares et al. 41.

FIGURE 4. Distribution map of Syagrus amicorum in the state of Bahia, Brazil marked on the black spot.