Sloanea dussii Urb., Symb. Ant.

Ferlay, Benjamin & Thésée, Alexandre, 2025, First observation of the flowers of Sloanea dussii (Eleocarpaceae), a tree endemic to Martinique (Lesser Antilles): ecological, morphological, and taxonomical insights, Phytotaxa 690 (2), pp. 285-292 : 286-291

Sloanea dussii Urb., Symb. Ant. 1: 361 (1899)

Lectotype (here designated): —MARTINIQUE. 1884, Duss no. 1368 ( US, barcode 00098554, Digital image!, image available at https:// www.gbif.org/tools/zoom/simple.html?src=//api.gbif.org/v1/image/cache/occurrence/1321267210/media/a32444111a935b2f4efdb6 60a49e9951)

Epitype (here designated): — MARTINIQUE. Fontaine Absalon, Camp Colson, Morne Vert, fr., 1884, 1889, P.A. Duss nos. 1368, 4042 [detached fruits] (NY, barcode 00084156!, image available at https://sweetgum.nybg.org/science/vh/specimen-details/?irn=553175).

Illustrations: — Rollet (2010, Fig. 6F–H); Pennington & Wise (2017, Fig. 115A–F). ( Figs. 2–3 ).

Diagnosis: — Sloanea dussii is distinguished from other species from the Lesser Antilles by its heteromorphic, semirigid capsule spines. In contrast, S. dentata has longer, distinctly curved spines, while S. truncata bears monomorphic, flexible, and conspicuously antrorse-hispidulous spines. Regarding flowers, S. dussii is characterized by 5–9 sepals unequal in terms of size and shape, as well as by pubescent anthers and filaments, the latter ones up to 2 mm in length. In comparison, S. truncata and S. dentata share similar sepal characteristics but differ in the glabrous filaments and anthers of S. truncata , and in the longer filaments (2.5–5 mm) of S. dentata . Vegetatively, S. dussii shows pubescent leaves (at least along the midrib), entire, linear, and rapidly caducous stipules, as well as wedge-shaped leaf bases. In contrast, S. dentata has persistent, dentate or laciniate stipules, while S. truncata also has caducous stipules, but with broadly truncate leaf bases. Sloanea berteroana and S. caribaea lack spines on their capsules, possess only four equal sepals and glabrous leaves, even along the veins.

Description:— Large tree, up to 40 m tall, to 80 cm diameter at breast height; branching high above the ground, with pyramidal outline. Buttresses winged, developed in width, up to 2 m high. Bark smooth, gray-brown to reddishbrown, orange-flecked carmine when scraped. Apical buds 4–5 × 1.5–2.2 mm, ellipsoid to lanceolate, apex acute to rounded, densely coarse-pubescent, surrounded by stipules, twigs ca. 3 mm diameter, eventually glabrous or glabrescent, greyish-brown with some lenticels. Stipules linear-subulate to narrowly lanceolate, 4–12 × 1–2 mm, entire, coarsely pubescent, readily caducous. Leaves alternate, spirally arranged, not clustered on low branches, clustered on the highest branches; the leaves exposed to the sun much smaller than those in the shade, coriaceous, with revolute margins. Petioles 0.4–2 mm long, puberulent to pubescent, canaliculate. Blades broadly oblanceolate, 4–15 × 2.3–7.5 cm, obtuse on the exposed leaves, base acute, margin entire or obscurely crenulated especially towards the apex, chartaceous when young, apex acute to shortly acuminate on shaded leaves, sparsely pubescent on midrib above, with sparse coarse hairs along midrib below, the rest glabrous; venation craspedodromous, midrib slightly sunken above, secondary veins 6–11 pairs, ascending, slightly arcuate, parallel or sightly convergent, tertiaries few, oblique and parallel, with fine reticulum visible below. Inflorescences axillary, often grouped under the leaves at the tips of the branches, 1–2 cm long, in loose, puberulent racemes, of 4–6 flowers; peduncle 0.5–2 mm long; pedicels 4–9 mm long, lengthening at the end of flowering. Sepals narrowly triangular or lanceolate, 4–7, 1.5–3 × 1–2 mm, often unequal, free, membranous, puberulent on both sides, aestivation open, some persistent below fruit. Petals absent. Receptacle 2–3 mm in diameter, flat and becoming convex when mature, pitted, densely pubescent by short hairs. Stamens 45–60, filament almost absent at the opening, ca. 0.5 mm long at anthesis, accrescent to 2 mm at the end of flowering, pubescent with spread hairs; anthers ellipsoid, ca. 1 mm long, pubescent with more or less appressed hairs, dehiscing by a lateral slit. Ovary ovoid, 2–3 mm long, often 4-angled (especially at the base), densely pubescent with short hairs, 4-locular; style ca. 2.5 mm long, extending beyond the stamens by about 2 mm on young flowers, pubescent in the lower half, becoming glabrous at the apex, 4-lobed at the apex (lobes very short, ca. 0.5 mm long). Capsules ovoid, 2–2.5 × 1.5 cm (without spines), apex acute, base truncate, puberulous, 4-valved, valves 4–6 mm thick, red and smooth inside, densely spined outside; spines heteromorphic, deciduous, the longest ones up to 10 mm long, tapering from the expanded base (ca. 1 mm diameter) to the sharp apex, stiff, slightly curving, cylindrical in section, with sparse minute antrorse hairs, the smallest ones 1–2 mm long, not or slightly tapering from the base to the apex. Seeds solitary in each lodge, only one of these lodge carrying a viable seed, the others aborting; the viable seed elliptic-ovoid, ca. 10 × 4 mm, completely covered by the aril.

Etymology: —The specific epithet dussii refers to the Swiss botanist Père Antoine Duss (1840–1924), the first collector of this species. It’s important to note that Pennington (2016, 2017) made a spelling error with the epithet by writing dussei (Pennington, pers. comm.). According to Article 60.8 (b) of Turland et al. (2018), the epithet dussii is the correct one.

Localnames: —Chataignier-coco(Chatennyékoko),Chatignier-petit-coco(Chatennyétikoko),Petit-coco(Tikoko) (Duss1897).Notethat S.berteroana hasthesamelocalnames,becausethetwospecieshavelongbeenconfused( Rollet2010).

Uses: —Like other species of Sloanea from the Lesser Antilles, S. dussii was sought after for its very hard wood, which was used for construction (Duss 1897).

Phenology: —An evergreen species; observations of the flowers were made in June, the fruits ripening in January of the following year on the same tree. In 1986, the species was observed fruiting in August. In 2021, several individuals were observed with capsules dehiscing in May and June. Therefore, it seems that the species might flower and fruit throughout the year.

Flowering frequency is unknown, the species may not flower every year, as is the case of S. caribaea in the West Indies which only flowers once every 3 or 4 years (Duss 1897).

Additional specimens examined: — MARTINIQUE. Plateau Concorde , 8 October 1983, Barrier 4406 ( P!) ; Plateau Concorde , November 1987, Fiard 339 ( MTK!) ; Morne Jeannette , 4 May 2010, Flériag 12 ( MTK!) ; Morne Obely , 25 June 2023, Ferlay 2577 ( MTK!) ; without locality, Rollet 1676 ( GUAD!, without label) .

Distribution and habitats: —It is found in low to medium elevation humid forests, between 300 and 600 m ( Stehlé 1947). At these elevations, it can be found along river banks, on slopes and ridges, geographically around the Montagne Pelée and the Pitons du Carbet ( Fig. 1 ). The species is found with other species characteristic of these habitats, such as other species of Sloanea , Dacryodes excelsa Vahl (1810: 116) , Magnolia dodecapetala ( Lamarck 1786: 127) Govaerts (1996: 70) , Tapura latifolia Bentham (1853: 291) , Simarouba amara Aublet (1775: 860) and Chimarrhis cymosa Jacquin (1763: 61) .

Conservation status: —The species is strictly endemic to Martinique. More than twenty populations are known and include numerous individuals, but only few bear seeds. In addition, most populations are found in protected areas, and the species is included in the list of protected species in Martinique (ministerial decree). The species does not appear to be threatened, and we propose classifying it as LC (Least Concern) here.

Typification of the name Sloanea dussii : —In the protologue, Urban (1899: 361) cited two gatherings (syntypes according to the Art. 9.6 of ICN) as “ Duss 148, 1368 ”. Furthermore, Urban (1899: 361) reported “ Sloanea spec. Duss.! Flor. Ant. franc. (1897) p. 92 ” which refers to Duss’ (1897) work “Flore phanérogamique des Antilles françaises”. It is to be noted that Duss (1897: 92) associated the unnamed new species (“ S. [ Sloanea ] (spec.)”) to a “Spécimen sans fleurs” no. 1363, not 1368 as reported by Urban (1899: 361). This seems a Duss’ mistake, because Duss (1897: 88‒89) himself linked the number 1363 to another species, i.e. Triumfetta lappula Linnaeus (1753: 444 ; image available at http://n 2t.net/ark:/65665/3bbbdbd3c-95f4-4f5f-a1fb-b4b167ab84b7); moreover, in all the Duss’ specimens found referred to his collection of Sloanea in Martinique (at US and NY), the number 1368 is reported (see below).Herbarium and types of Antoine Duss from Martinique are preserved at A, B (most likely destroyed in Berlin according to Hiepko 1987; P. Juraj, pers. comm.), C, F, GH, LD, LE, MICH, MO, NY, P, PC, S, U, and US (see HUH-Index of Botanists 2013+). We traced four pertinent specimens at P, NY, and US:

Ḁ P00409880 (image available at http://mediaphoto.mnhn.fr/media/1441365020892Afbhuv3miASkLr3a): it represents a Duss’ collection no. 148 of Capsicum Linnaeus (1753: 188) from Guadeloupe and, therefore, it cannot be considered as part of the original material for Sloanea dussii ;

Ḁ US 00098554: some parts of branches of a same collection from Martinique (year 1884) are pinned on this sheet; the number 1368 is annotated on the label. This specimen is part of the original material for Sloanea dussii ;

Ḁ NY00084155 and NY00084156: these two specimens include, each, one label including the same annotations, i.e. the locality of collection (“ Fontaine Absalon, Camp Colson… 400–700 m ”), collection numbers (“ 1368 ” and “ 4042 ”), and year of colletions (“ 1884 ” and “ 1889 ”). Since the aforementioned specimen ( US 00098554) bears a plant collected in 1884 and numbered with 1368, the two NY specimens bear two collections, one in 1884 (numbered with 1368) and the other one in 1889 (numbered with 4042). Unfortunately, no evidence allows to link the various exiccata on NY sheets with the date/number. In other words, material occurring on these two NY sheets came from more than one gathering, with multiple localities and dates specified on the label (cf. Turland et al. 2018, Art.8.2, Note 1). Therefore, we cannot distinguish them for the lectotypification purpose. However, based on the discussion above, Pennington’s typification (2016: 8) is ambiguous (which collections between nos. 1368 and 4042?) and, furthermore, there is no possibility to verify which exsiccatum is linked to which collection number. As a consequence, Pennington’s proposal cannot be retained and a new lectotypification is necessary.

Smith (1954) and Howard (1989) stated that Sloanea dussii was only known from one sheet with two gatherings (NY00084155, NY00084156) labeled with “ Duss 1368, 4042 ”. Furthermore, the only localities known to Duss (1897) and Urban (1899) were “Absalon et du Champflore (bord de la rivière Claire)”. It is possible that the number 148 was added by A. Duss in a subsequent time and later replaced by Duss 4042; it is also possible that Duss 4042 would represent a later gathering. Lacking further information, no definitive conclusion can be given and doubts remains about this matter.

Finally, we highlight that Stehlé (1947: 304) cited a further Duss’ gathering (Duss 1362) which, however, has not traced by us.

All things considered, only US 00098554 is an unambiguous original material and we designate it as the lectotype of the name Sloanea dussii (morphology of US specimens matches Urban’s description). Concerning the identity of the lectotype according to the current concept of Sloanea , since the absence of flowers and fruits, we here propose to designate an epitype (NY00084156) which serve as an interpretative type (Art. 9.9 of ICN).

Smith (1954), most probably due to poor available material, placed Sloanea dussii into the subgenus Quadrisepala Smith (1954: 76) and the section Corymbo-racemi, basing the presence of 4 sepals and characters of the capsule (rigid spines). On the contrary, Pennington (2017) placed S. dussii in the subgenus Sloanea , section Brevispicae . Thanks to the material recently collected, it is now possible to confirm that S. dussii belongs to this subgenus and section of the genus recognized by Pennington (2017), which is characterized by 4–11 unequal sepals which do not cover the reproductive organs in bud, and caducous stipules (obs. pers., B. Ferlay 2577).

Note that Fournet sample a young shoot from a 3 m young tree, at the top of the Crête de Village (Fournet 4708, GUAD!). This specimen was identified as S. dussii . However, it is not possible to truly attest to the identification of this specimen, especially since the identification criteria might differ in young individuals.

Figures

FIGURE 1. Map of the geographic distribution of S. dussii.

FIGURE 2. Herbarium specimen of Sloanea dussii with inflorescences and flowers, Ferlay 2577 (MTK No. 6556).

FIGURE 3. S. dussii (A–C. from the fresh specimen of Ferlay 2577; D. from the specimen sample of Ferlay 2577, 2868; from the fresh specimen of Ferlay 2858). A. Branch with inflorescences. B. Detail of an inflorescence. C. Detail of flowers. D. Trunk. E. Capsules.