Revision of the Neotropical genus Desmopsis ( Annonaceae )

A taxonomic revision of the genus Desmopsis is presented. Within the genus Desmopsis 25 species are recognized, 9 of which are new, with one new combination. Distinguishing morphological characteristics are discussed, and a dichotomous key to all species is given. The species treatments include descriptions, full synonymy, geographical and ecological notes, vernacular names, and taxonomic notes. Distribution maps are presented of all species, and a complete identification list of exsiccatae examined is included.


INTRODUCTION
While working in the Office of Economic and Systematic Botany of the Bureau of Plant Industry within the United States Department of Agriculture during the early 20th century, William E. Safford (1859Safford ( -1926) ) conducted taxonomic research on various groups including Acacia, Cactaceae, and Annonaceae.Among the six genera of Annonaceae Safford described, only two currently remain accepted: Desmopsis and Fusaea.Safford (1916) proposed the genus Desmopsis to accommodate three previously described species along with two newly described species from Central America with leaf-opposed flowers borne on bracteate pedicels, and apocarpous fruits consisting of stipitate, berry-like monocarps.Among his series of revisions of Neotropical genera of Annonaceae, Fries (1930) recognized 8 species of Desmopsis.Subsequent descriptions of new species of Desmopsis by Fries (1931Fries ( , 1941Fries ( , 1948)), Lundell (1939), and Standley (1932, andin Standley &Steyermark 1944) brought the total number of Desmopsis species recognized by Fries (1959) to 16.Since then, several additional species have been described (Lundell 1974, Erkens et al. 2006, Jiménez-Ramírez & González-Martínez 2016), and several nomenclatural rearrangements have been proposed (Maas et al. 1994).Based on the examination of over 1 000 exsiccatae, the current work recognizes 25 species of Desmopsis, including one new combination and 9 new species.

Habit
Species of Desmopsis are shrubs to small trees usually less than 10 m tall, rarely to 20 m tall in D. dukei and D. schippii.The main trunk is slender in species for which diameter has been recorded, usually less than 10 cm diam, rarely to 30 cm diam in D. schippii.

Leaves
Leaves are simple, entire, petiolate, and estipulate, and arranged alternately in a single plane along lateral branches (distichous).Petioles are usually short, less than 10 mm long, the longest petioles found in D. biseriata (5-15 mm), D. wendtii (7-15 mm), and D. verrucipes (5 -20 mm).The shape of the lamina is narrowly elliptic to elliptic, occasionally narrowly ovate to ovate or obovate, or rarely rhombic-obovate to circular in D. neglecta.The texture varies from membranous to chartaceous to rarely subcoriaceous (D. neglecta), the surface dull to shiny and often smooth, but occasionally verruculose above and below, with glandular oil bodies evident in D. guerrerensis.The lamina is usually 10 -20 cm long, with small leaves occurring in D. lanceolata (4 -10 cm), D. neglecta (2 -8 cm), and D. talamancana (5 -9 cm), and especially large leaves occurring in D. biseriata (17-42 cm), D. heteropetala (15 -40 cm), D. nigrescens (15-30 cm), and D. verrucipes (16-40 cm).The base of the lamina is attenuate to acute to less often obtuse, or rarely distinctly cordate in D. heteropetala.The apex of the lamina is generally acute to acuminate, the acumen 2 -25 mm long, or rarely obtuse, with the extreme tip often distinctly obtuse to rounded.The primary vein is distinctly impressed or sometimes flat above.The venation is brochidodromous with 5 -15 secondary veins per side, the tertiary venation reticulate to rarely percurrent.The indument on young branches, petioles, and lamina is composed of simple appressed or erect hairs.In most species of Desmopsis the lower side of the leaves is glabrous or nearly so, less often sparsely covered with appressed hairs, or densely covered with long-persisting, erect hairs in D. confusa, D. dukei, D. oerstedii, and D. trunciflora.

Inflorescences
Inflorescences are terminal rhipidia, usually appearing leafopposed by the overtopping of the renewal shoot and mostly bearing 1 or 2 flowers (rarely up to 15); inflorescences are sometimes borne on the main trunk, occasionally so in D. confusa, D. dolichopetala, D. schippii, D. subnuda, and D. verrucipes, and exclusively so in D. wendtii.The pedicel (here measured as the entire stalk both below and above the articulation, i.e., including the peduncle) bears a basal bract at the articulation and a second bract higher up toward the flower, the bracts either

Fruit
Fruits are apocarpous, consisting of 2-40, free, stipitate or rarely subsessile, berry-like monocarps.The stipe varies in length from < 1 to 35 mm, with short stipes found in D. dolichopetela (3-6 mm), D. lanceolata (2-5 mm), D. mexicana (3-5 mm), D. neglecta (< 1-3 mm), D. schippii (1-5 mm), D. subnuda (3-7 mm), D. talamancana (3-7 mm), and D. trunciflora (2-3 mm).The monocarps vary in size from 5 to 45 mm long by 5 to 27 mm in diameter, and in shape from spherical to ellipsoid to oblongoid.Upon drying, the monocarps are sometimes slightly to strongly constricted between the seeds.The wall of the monocarps is usually thin (0.1-1 mm thick), but especially thick monocarp walls are found in D. heteropetala (2-4 mm), D. oerstedii (2-4 mm), and D. talamancana (1-1.5 mm).Seeds vary in number from 1 to 14, and are of various shapes depending on the number of seeds in the monocarp, their position, and whether there are one or two rows.Seeds in monocarps with only a single seed are spherical or subspherical to ellipsoid; seeds in monocarps with two seeds, or the seeds at either end in monocarps with three or more seeds in a single row are hemispherical; seeds in middle positions of monocarps with three or more seeds in a single row are discoid; seeds in the middle positions of monocarps with seeds in two rows are hemidiscoid; and seeds at either end in monocarps with seeds in two rows are quartispherical.Seeds bear a distinct encircling raphe, and the seed coat can be either smooth, grooved and/or pitted with the endosperm ruminations peg-shaped to lamellate.

THE PHYLOGENETIC POSITION OF DESMOPSIS WITHIN ANNONACEAE
Desmopsis has been placed in tribe Miliuseae of subfamily Malmeoideae (Chatrou et al. 2012).A recent plastid phylogeny of tribe Miliuseae (Chaowasku et al. 2014) recovered Desmop sis in a clade of Mesoamerican taxa sister to Stenanona, the two of them in turn sister to an undescribed species from Mexico also referred to Desmopsis.Together, Desmopsis, Stenanona, and the undescribed species are sister to the other Mesoamerican genera Sapranthus (Schatz et al. 2018) and Tridimeris.This Mesoamerican clade of Miliuseae is nested in a larger clade of Asian genera, and most closely related to an undescribed genus from Thailand, and Meiogyne.Desmopsis was distinguished from Stenanona in a revision of the latter genus (Schatz & Maas 2010) by its thicker, stiffer petals lacking venation, and its disulculate boat-shaped pollen (vs inaperturate globose pollen in Stenanona).A more recent molecular phylogenetic study of the Neotropical Miliuseae (Ortiz-Rodriguez et al. 2016), which formally described the clade as subtribe Sapranthinae, has revealed the possibility that Desmopsis and Stenanona as currently circumscribed may not be monophyletic, and might best be treated as a more broadly circumscribed Desmopsis, or alternatively be carved into multiple genera.However, some of the branches and nodes in the phylogeny lack adequate support values, nor is the taxon sampling comprehensive.Until the molecular phylogenetic results are fully resolved, the current revision treats Desmopsis in its traditional sense.Habitat & Ecology -In evergreen to semi-evergreen to rarely deciduous forest.From sea level to 2000 m.Note -The genus was given its name because of its resemblance to the Old World genus Desmos.Note -Typical D. bibracteata is distinguished, by its acute apex (with the extreme tip obtuse to rounded), relatively small leaves, small petals with the extreme tip rounded and brown in sicco, having margins that are revolute, and mostly strongly constricted and thin-walled monocarps.Moreover, both bracts are leafy and often persistent.Note -Desmopsis biseriata can be recognized by its relatively large monocarps (12 -30 by 12 -20 mm) with seeds arranged in two rows, borne on relatively long stipes (10 -25 mm long), combined with large leaves up to 42 cm long, and relatively short pedicels (20 -25 mm long).glabrous above, except for some hairs along primary vein, rather densely to sparsely covered with appressed hairs below, base obtuse and slightly attenuate, apex acute to acuminate (acumen 5 -10 mm long), primary vein impressed above, secondary veins 6 -8 on either side of primary vein, slightly raised above, tertiary veins slightly raised above, reticulate.

Desmopsis brachypoda
Inflorescence and flower indument: pedicels and outer side of bracts, sepals, and petals densely to rather densely covered with appressed hairs.Note -Desmopsis brachypoda is distinguished by its relatively short pedicels (10-15 mm long), hence the specific name.It is also characterized by an indument of appressed hairs on the lower leaf side, and a relatively low number of secondary veins (only 6 -8).Notes -Desmopsis colombiana occurs in the Río Claro region in Antioquia.It is characterized by minute, scale-like bracts, relatively short pedicels (10 -30 mm long), few monocarps (2 -4), and small sepals (1-2 mm long).
Inflorescence and flower indument: pedicels and outer side of bracts, and sepals densely to rather densely covered with erect hairs (velutinous), petals densely to rather densely covered with mainly appressed hairs.Inflorescences 1-or 2-flowered, leaf-opposed, but sometimes produced from the main trunk; pedicels 50 -70 mm long, 0.5 -1 mm diam, to 60 -120 mm long and 1-2 mm diam in fruit; basal bract leafy, broadly ovate to broadly ovate-cordate, 2 -25 by 3 -20 mm, upper bract scale- Note -Desmopsis dukei can be recognized by the longpersisting indument of erect hairs on the pedicels and lower side of leaves and relatively short pedicels (10 -25 mm long).
Note -Desmopsis heteropetala is easily recognizable by its large leaves with a cordate base, and primary vein strongly keeled on the lower side.The monocarps are large (20 -38 mm long), spherical to ellipsoid, and without any constriction between the two rows of seeds.Moreover, the monocarps are very thick-walled (wall to 4 mm thick).

Desmopsis lanceolata Lundell -Map 6
Desmopsis lanceolata Lundell (1939)  Shrub or tree 2.5-6 m tall, diam not recorded; young twigs and petiole densely covered with erect and appressed, golden brownish hairs.Leaves: petiole 2-8 mm long, c. 1 mm diam; lamina narrowly elliptic, 4-10 by 1-3.5 cm, chartaceous, shiny, sometimes the primary vein covered with some erect hairs to glabrous above, sparsely covered with appressed and erect hairs below, but primary vein densely so to glabrous, base acute, apex acute to obtuse, sometimes shortly acuminate (acumen to c. 5 mm long), the extreme tip rounded, primary vein impressed above, secondary veins 6 -10 on either side of primary vein, raised to flat above, tertiary veins flat to slightly raised above, reticulate.
Inflorescence and flower indument: pedicels and outer side of bracts and sepals densely to rather densely covered with erect and appressed hairs, outer side of petals rather densely covered with appressed hairs.Inflorescences 1-or 2-flowered, leaf-opposed; pedicels 15 -20 by c. 1 mm diam, to c. 25 mm long and c. 1 mm diam in fruit; basal bract leafy, broadly ovate Vernacular names -Not recorded.
Leaves: petiole 3 -5 mm long, 1-2 mm diam; lamina elliptic, 7-15 by 3 -6 cm, chartaceous, shiny and glabrous above, soon glabrous below, but sparsely covered with appressed hairs mainly along primary vein, base obtuse to rounded, rarely acute, apex obtuse to acute to rarely acuminate, the extreme tip rounded, primary vein impressed above, secondary veins 6-10 on either side of primary vein, raised above, tertiary veins raised above, reticulate.Inflorescence and flower indument: pedicels and outer side of bracts, sepals, and petals sparsely to densely covered with appressed hairs.Vernacular names -Not recorded.

Desmopsis microcarpa
Leaves: petiole 1-4 mm long, c. 1 mm diam; lamina broadly rhombic-obovate to circular, 2-8 by 1.5-5 cm, subcoriaceous, margins slightly revolute, shiny and glabrous on both sides, but with some soon falling erect hairs along primary vein below, base acute to obtuse, slightly oblique, apex acuminate (acumen 5 -20 mm long), the extreme tip obtuse to rounded, often curved to one side, primary vein slightly impressed above, secondary veins 5 -13 on either side of primary vein, raised above, tertiary veins raised above, reticulate.Inflorescence and flower indument: pedicels and outer side of bracts, sepals densely covered with erect and appressed hairs, petals rather densely covered with appressed hairs.Note -Desmopsis neglecta is very peculiar in being the only species of the genus occurring in the Caribbean on Cuba.It is distinguished by its small, almost rhombic leaves, short pedicels bearing scale-like bracts at nearly the same level, and subsessile monocarps.Tree 2 -12 m tall, c. 6 cm diam; young twigs and petioles glabrous.Leaves: petiole 3 -11 mm long, 2 -3 mm diam; lamina generally drying black, narrowly elliptic to elliptic, sometimes narrowly obovate, 15 -30 by 5 -14 cm, coriaceous, glabrous above, glabrous below, except for some scattered hairs along primary vein, base acute to obtuse, apex acuminate (acumen 10 -25 mm long), primary vein impressed above, secondary veins 9-12 on either side of primary vein, raised above, tertiary veins raised above, reticulate.Inflorescence and flower indument: outer side of bracts glabrous, pedicels and outer side of sepals sparsely to rather densely covered with brown, curly hairs, outer side of petals rather densely to sparsely covered with appressed hairs.Note -Desmopsis nigrescens is very well marked by its large leaves (15 -30 by 5 -14 cm) drying black (hence the specific name), and relatively large sepals (to 22 by 14 mm in fruit) which are often persistent in fruit.It might be confused with D. maxonii, which, however, has smaller, non-accrescent sepals (3 -8 by 3 -6 mm) that are not persistent in fruit.Moreover, D. nigrescens occurs at lower elevations (0 -750 m) than D. maxonii (600 -2000 m).Shrub or tree 2 -10 m tall, c. 15 cm diam; young twigs and petiole densely covered with long-persisting, brownish, erect hairs (velutinous) 0.2 -0.3 mm long.Leaves: petiole 4 -7 mm long, c. 1 mm diam; lamina narrowly elliptic to elliptic, 5 -14 by 3 -6 cm, chartaceous, glossy and glabrous above, except for erect hairs along primary vein, densely covered with longpersisting, brownish, erect hairs (velutinous) 0.2 -0.4 mm long below, base acute, apex acute to acuminate (acumen 5-10 mm long), primary vein impressed above, secondary veins 8 -11, slightly raised above, tertiary veins flat to slightly raised above, reticulate.Inflorescence and flower indument: pedicels and outer side of bracts densely covered with brownish, erect hairs (velutinous) 0.2-0.3mm long.Inflorescence: flowers not seen.
Vernacular names -Not recorded.
Habitat & Ecology -In lowland rain forests.At elevations of 0 -800 m.Flowering: September to April; fruiting: all year through.
Notes -Desmopsis panamensis is characterized by a brown to white indument of appressed and erect more or less curly hairs on the young twigs, small sepals (2 -5 mm long), and relatively long pedicels (30 -100 mm long).
On Barro Colorado Island the monocarps have a rather longpersisting indument.Tree or shrub 1.5 -20 m tall, 5 -30 cm diam; young twigs glabrous or sparsely covered with appressed hairs.Leaves: petiole 2 -8 mm long, 1-2 mm diam; lamina narrowly elliptic to elliptic, 8 -22 by 3 -9 cm, chartaceous, glabrous above, glabrous, but sparsely covered with appressed hairs along the primary vein below, base acute to obtuse, rarely attenuate, apex acute to acuminate (acumen 5 -20 mm long), the extreme tip obtuse, primary vein impressed above, secondary veins 6 -8 on either side of primary vein, slightly raised above, tertiary veins slightly raised above, reticulate.Inflorescence and flower indument: pedicels and outer side of bracts, sepals, and petals sparsely to densely covered with appressed hairs.Inflorescences 1-or 2-flowered, leaf-opposed, sometimes produced from the main trunk; pedicels 10 -80 mm long, 0.5 -  Fries (1931) is typified by Liebmann 4, and is here considered to represent a distinct species for which the combination D. subnuda is proposed.

21
. Desmopsis talamancana G.E. Schatz & Maas,; Map 7 Desmopsis talamancana is recognized by its relatively small, glabrous leaves (5 -9 by 2 -5 cm), and a small number (5) of large monocarps (20 - Note -Desmopsis talamancana can be distinguished by its relatively small (5 -9 by 2 -5 cm), glabrous leaves with an attenuate base and acuminate apex, a leafy lower bract on the pedicel, and fruits with seeds in two rows.Its leaves are much smaller than other species with biseriate ovules, and it occurs at much higher elevation in Costa Rica than D. biseriata and D. heteropetala.Note -Desmopsis trunciflora is very well characterized among the species from Mexico by a dense indument of erect, long-persisting hairs on most parts of the plant.In the youngest leaves this indument is almost silvery coloured.In addition, the relatively low number of monocarps (c. 5) are borne on short stipes (2 -3 mm long).Habitat & Ecology -In medium to tall evergreen to semievergreen forest in deeper soil pockets within karstic limestone.At elevations of 100 -250 m.Flowering: January to May, October; fruiting: February to April, July, October.
Vernacular names -Not recorded.
Field observations -'Flowers with a fragrance of ripe banana, with an element of formalin ' (Wendt et al. 4053,Mexico).Note -The strictly trunciflorous habit distinguishes D. wend tii.The flower closely resembles those of the genus Guatteria, which, however, possess a single basal ovule, imbricate petals, and axillary inflorescences.The biseriate condition of the ovules is shared with a number of species from Costa Rica including D. biseriata (also from Panama), D. heteropetala, and D. talamancana.
, secondary veins 6 -8 on either side of primary vein, slightly raised above, tertiary veins raised to flat above, reticulate.Inflorescence and flower indument: pedicels and outer side of bracts glabrous or sometimes sparsely covered with appressed hairs, outer side of sepals and petals sparsely to rather densely covered with appressed hairs.