Coccothrinax argentea (Loddiges ex Schultes & Schultes) Sargent ex Schumann (1901: 469)

Henderson, Andrew, 2023, A revision of Coccothrinax, Hemithrinax, Leucothrinax, Thrinax, and Zombia (Arecaceae), Phytotaxa 614 (1), pp. 1-115 : 28-31

1.3. Coccothrinax argentea (Loddiges ex Schultes & Schultes) Sargent ex Schumann (1901: 469) .

Thrinax argentea Loddiges ex Schultes & Schultes (1830: 1300) .

Acanthorriza argentea (Loddiges ex Schultes & Schultes) Cook (1941: 50) .

Neotype (designated here):— DOMINICAN REPUBLIC. Haina, 26 July 1939, L. Bailey 269 (neotype BH!). Plate 3

Thrinax longistyla Beccari in Urban (1912: 170). Lectotype (designated here):— DOMINICAN REPUBLIC. Barahona, 0 m, June 1910, M. Fuertes 415 (holotype GH!, isotypes FI!, K!, the holotype at B was destroyed).

Stems 5.0(1.5–20.0) m long and 5.2(4.5–6.5) cm diameter, solitary or rarely clustered. Leaves more or less deciduous or only leaf bases persisting on stem; leaf sheath fibers 0.3(0.1–0.5) mm diameter, closely woven, forming persistent, triangular ligules at the apices; petioles 10.5(5.3–17.9) mm diameter just below the apex; palmans 14.8(4.3–32.0) cm long, relatively long, without prominent adaxial veins; leaf blades not wedge-shaped; segments 42(25–58) per leaf, the middle ones 53.1(32.0–75.0) cm long and 2.9(1.5–5.5) cm wide; segments not pendulous at the apices, giving the leaf a flat appearance; middle leaf segments relatively long and narrow, tapering from base to apex, scarcely folded, flexible and not leathery, a shoulder or constriction absent or poorly developed, the apices thin, deeply splitting and breaking off; middle leaf segment apices attenuate; leaf segments not waxy or sometimes with a deciduous, thin layer of wax adaxially, densely indumentose abaxially, with irregularly shaped, semi-persistent, interlocking, fimbriate hairs without an obvious center, with well-developed transverse veinlets. Inflorescences curving, arching, or pendulous amongst the leaves, with few partial inflorescences; rachis bracts somewhat flattened, loosely sheathing, usually tomentose with a dense tuft of erect hairs at the apex; partial inflorescences 4(2–5); proximalmost rachillae straight, 9.2(5.2–15.0) cm long and 1.3(0.9–1.9) mm diameter in fruit; rachillae glabrous at or near anthesis; stamens 8(6–10); fruit pedicels 0.8(0.3–2.5) mm long; fruits 7.7(5.6–9.1) mm long and 7.9(5.5–9.5) mm diameter, purple, dark purple, red-purple, reddish-purple, purple-black, red-pink, red-black, grayish-brown, blackish, or black; fruit surfaces smooth or sometimes with projecting fibers; seed surfaces deeply lobed, the lobes running from base of seeds almost to apices.

Distribution and habitat:— Hispaniola ( Haiti, Dominican Republic) ( Fig. 9 ) in deciduous or semi-deciduous forest, xeromorphic forest, pine forest, broad leaf forest, dry forest, or secondary forest, and persisting in disturbed areas, on limestone or serpentine soils, at 259(0–1,000) m elevation.

Taxonomic notes:— As a preliminary species Coccothrinax argentea was polymorphic for one variable (stem branching). However, splitting it into two species such that variables were consistent within each one led to improbable species that could not be justified morphologically or geographically. Therefore the polymorphic variable was treated as a trait and C. argentea is recognized as a phylogenetic species. Bailey (1939b) gave a discussion of the taxonomic history of C. argentea , and a detailed description based on a specimen (Bailey 269) that he had collected near Santo Domingo in the Dominican Republic. This specimen is designated here as the neotype. One other name has been applied to specimens from this area, Thrinax longistyla . Read (1975) considered this to be a Coccothrinax rather than a Thrinax , and it was included as a synonym of C. argentea by POWO (2023) and its type share all character states with other specimens.

Coccothrinax argentea is widespread in Hispaniola and appears to be a complicated and confusingly variable species.

Subspecific variation:—Specimens from several, different areas have relatively short palmans with prominent adaxial veins, approaching those of C. gracilis . For example, two specimens (Liogier 14587, 16128) from the north coast of the Dominican Republic, from limestone cliffs, have this kind of short palman. Other specimens from scattered localities, often on serpentine soils, also have short palmans, for example those from the Loma la Peguera, the site of a nickel mine with serpentine soils.

One specimen (Montero 436) has clustered stems. It is from near Puerto Plata in northern Dominican Republic, near an area with other unusual palms, including an unidentified Pseudophoenix ( Rodríguez-Peña et al. 2014) .

In the south-central part of the Dominican Republic specimens have fruits with projecting fibers (illustrated in Fernández & Gottschalk 2017, page 102), somewhat different from fruit surfaces of other specimens. The neotype has fruits with projecting fibers. The Botanical Garden in Santo Domingo is situated within this south-central part of the Dominican Republic and here, in an area presumed to be part of the original vegetation, plants have tall, slender stems that often curve or bend, and a small, compact crown of leaves. Such plants have not been seen in other parts of Hispaniola .

There are two unusual populations in the peninsula part of southwestern Haiti. One specimen (Zanoni 26116) from the central part of the peninsula has obvious transverse veinlets and long pedicels (like C. barbadensis ). In the extreme southwestern part of the peninsula there are five specimens. Three have long pedicels but two (Bartlett 17491, Henderson 1030) have short pedicels like those of most specimens of C. argentea from Hispaniola. All specimens of this extreme southwestern population are from roadsides or disturbed, hilly areas, mostly between Cavaillon and St. Louis-du-Sud.

According to several specimen labels, C. argentea and C. spissa occur together in mixed populations in some areas in Hispaniola. These two species can sometimes be difficult to distinguish and it seems likely that there are hybrids between them. Apart from its smaller size, C. argentea can usually be distinguished by its shorter, thinner, regularly arranged rachillae, It also usually has a persistent, triangular ligule ( Fig. 2A ). Specimens of C. argentea differ significantly from those of C. spissa in 10 variables (stem diameter, petiole width, palman length, number of segments, segment length, segment width, rachilla length, rachillae width, fruit length, fruit diameter), with C. argentea having lower values for all variables (t- test, P <0.05).

Figures

FIGURE 2. A. Sheath fibers thin (usually <0.5 mm diameter), closely woven, forming persistent, triangular ligules at the apices (C. argentea). B. Sheath fibers thin (usually <0.5 mm diameter), flimsy, loosely woven, free and greatly elongate at the apices (C. crinita). C. Sheath fibers stout (usually>1 mm diameter), woody, loosely (rarely closely) woven, ± joined or briefly free at the apices (C. miraguama). D. Sheath fibers stout (usually>1 mm diameter), woody, loosely woven, the inner and outer layer combining at the apices to form erect, spine-like fibers (C. salvatoris).

PLATE 3. Coccothrinax argentea, Dominican Republic, with leaf segments not pendulous at the apices, giving the leaf a flat appearance.

FIGURE 9. Distribution of Coccothrinax argentea and C. barbadensis.