INTRODUCTION

The Araceae family comprises around 3645 species, of which 2113 are found in the Neotropics (^{Boyce & Croat, 2018}), and Colombia, with more than 818 species, is one of the most diverse countries per unit area in this family (Galeano et al., 2015). The genera with more species in Colombia are Anthurium Schott with 358, Philodendron Schott with 205, Xanthosoma Schott with 60, Chlorospatha Engl. with 48 and Stenospermation Schott, with 42 (Galeano et al., 2015, Croat et al., 2107). Despite the efforts to understand the Araceae flora in Colombia, there are still information gaps in various regions of the country. According to Boyce & Croat (2018) Stenospermation has ca. 62 published names and 50 accepted species, but 250 species are estimated to exist (100 to 150 in Colombia), making Colombia home to about 84% of the accepted species and between 40 and 60% of the estimated species for the genus. Since the first species of Stenospermation were published (^{Poeppig, 1845}), several species have been described, but it was not until 1908 that Engler & Krause published the first taxonomic key for 21 species of the genus. Later, Gómez (1983) made a taxonomic revision of Stenospermation for Central America, including nine species, and ^{Castaño-Rubiano (2011}) made a taxonomic revision of Stenospermation for Colombia, including 42 species. Furthermore, although several molecular phylogenetic studies have focused on the family level, few have included Neotropical taxa, and of those studies, few species of Stenospermation have been studied. ^{Zuluaga et al. (2019}) in a molecular study of the subfamily Monsteroideae included nine Stenospermation species, but many of them were unidentified. This is partly due to the lack of a taxonomic revision for the genus that includes all the species. Stenospermation is a neotropical genus growing from 0 to 2900 m a.s.l., being more diverse at 1500 m a.s.l. in primary mountain forests of Colombia, Ecuador and Perú (Castaño-Rubiano, 2011). The genus Stenospermation, is one of the most poorly known and most difficult to identify taxonomically within the Araceae family (^{Bunting, 1979}; Gómez, 1983). Several species have few characters traditionally used for their taxonomy (i.e. proportion of petioles/blades, proportion long/wide of the blades, color of spathe and seed shape, etc.) which makes them difficult to characterize. Likewise, the slight interspecific variation and the deficient collections are also common within the Monsteroideae subfamily, which has caused a long history of taxonomic changes (Henriquez et al., 2020; Zuluaga et al., 2019). According to Castaño-Rubiano (2011, 2015), in the case of Stenospermation, the low number of reported species in most regions Colombia are not due to environmental factors but the lack of botanical explorations, and for this reason, it is probable that a significant number of species will be reported as new to science. This was the case with the National Natural Park Selva de Florencia, where following the signing of peace agreements in 2016, areas previously restricted due to the presence of illegal armed groups and anti-personnel mines were opened up for scientific exploration. In a similar way, in the corregimiento de Berlín in Samaná Municipality, hydroelectric projects have facilitated ongoing monitoring of the impacted areas, allowing us to observe the flora over time. By undertaking projects within the study area and examining herbarium specimens as part of a taxonomic revision of Stenospermation in Colombia, the authors found three distinct species that do not correspond to any previously documented Stenospermation species.

MATERIALS AND METHODS

To confirm the identity of the species, specialized bibliography was consulted (^{Engler & Krause, 1908}; Gómez, 1983; ^{Castaño-Rubiano, 2011}; 2015), as well as the type specimens and other collections from Colombian herbaria (ANDES, CAUP, COAH, COL, CUVC, FAUC, FMB, PSO, HUA, HUAZ, HUQ, JAUM, JBB, MEDEL, UDBC) and foreign herbaria (AAU, AHUC, B, C, CSB, DAV, ECON, F, GH, GB, IBE, K, MO, NY, QCA, QCNE, US, USM, WIS; acronyms following Thiers, 2023). The species concept used was morphological (Crisci, 1994; ^{McDade, 1995}). The terminology used in the descriptions was based on ^{Beentje (2010}), Castaño-Rubiano (2011), and Croat & ^{Bunting (1979}) with modifications, in order to include the term “marginal band” proposed by Korn (2003) which seems to be informative for the species of Stenospermation. For Stenospermation albifolium all measurements in the descriptions are from dry material unless otherwise specified. In S. melidae and S. selvaflorensis all measurements and colors in the descriptions are from dry and fresh material and it is specified in the text. For the definition of the life form, we follow ^{Zotz et al. (2021}).

TAXONOMIC TREATMENT

Stenospermation albifolium Castaño-Rubiano, sp. nov. TYPE: COLOMBIA. Depto. Caldas. Munic. Samaná, corregimiento de Florencia, PNN Selva de Florencia, vereda San Lucas, Río San Lucas, cascada cerca de la casa de Evangelista, 5° 30’ 02.3’’ N, 75° 03’ 06.7’’ W, 1203 m s.m., 4 -VII-2021 (fl.), N. Castaño-Rubiano 2354 (holotype FAUC-39055!; isotype COL!). Figs. 1, 2, 3.

Diagnosis. Similar to S. glaucophyllum Croat & D.C. Bay by its whitish leaves beneath, but differs in lacking an evident layer of white wax, sheath truncate on one side, semiacute on the other and entire margin (vs. rounded on one side, acute on the other and scarious margin), spathe meeting on the peduncle at an obtuse angle (vs. spathe meeting on the peduncle at an acute angle), and spadix slightly tapered toward the apex (vs. cylindric and rounded at the apex).

Description. Terrestrial herb, 1.5 m tall. Stem with internodes 30-60 mm long × 16-20 mm diam., glossy when fresh, 11-44 mm long, 8-11 mm diam.; cataphylls not observed. Leaves erect; petioles 16-20 × 0.4-0.6 cm diam. when fresh, 11-19 cm long × 0.25-0.40 mm; geniculum concolorous, 15-40 mm long, 2.4-3.6 mm diam; sheath 10-15 × 0.5-0.8 cm, covering (58-)75-87% of the petiole in regular blades, 100% on those subtending the spadix, apex truncate on one side, semiacute on the other, entire margin; blades 18-26 × 8-13 cm, elliptic, one side broader than the other, obtuse at base, acuminate at apex, coriaceous; upper surface glossy, dark green, drying olive-green; lower surface somewhat glossy, pale green to white, drying light green to whitish; midrib sunken, paler than blade above, U-shaped below; primary lateral veins slightly conspicuous on the upper surface, conspicuous on the lower surface, about 30-40 per side, slightly arched, starting from an angle of 45-50°; tertiary veins less prominent than primary lateral veins, on both surface marginal band narrow 1.0-1.5 mm, bent towards the underside.

Fig 1 Distribution map of S. albifolium, S. melidae and S. selvaflorensis. Color version at https://www.ojs.darwin. edu.ar/index.php/darwiniana/article/view/1134/1316 

Fig 2 Stenospermation albifolium. A, branch with inmature inflorescence. B, C, apex of the sheet. D, spadix. E, immature infructescence. F, stylar zone an stigma. G, lateral view of the flower. H, stamens. Drawn by Eileen Muñoz, based in: N. Castaño-Rubiano 2209, 2354. 

Fig 3 Stenospermation albifolium. A, habitat. B, immature inflorescence and leaves. C, immature spathe and spadix. D, stipe of the spadix.. E, Spathe. F, capitate inflorescence before fruit formation. G, apex of the sheet. Color version at https://www.ojs.darwin.edu.ar/index.php/darwiniana/article/view/1134/1316 

Inflorescences erect; peduncles 23-24 cm long × 0.5 cm diam. when fresh, (11-)19-20 cm long × 0.22-0.33 cm diam; spathes 11 cm long × 3.2 cm width., papyraceus, naviculiform, meeting on the peduncle at an obtuse angle, immature spathe green, mature white, shiny, long attenuated at the apex, deciduous; stipe 2.0 cm long, 0.5 cm diam. when fresh, 1.0-1.5 cm long, 0.2-0.21 cm diam.; spadix 5 cm long, 0.13 cm diam. when fresh, 5-5.1 cm long, 0.90-0.91 mm diam. white, slightly tapered toward the apex when flowering, becoming capitate before fruit development. Flowers 0.18-0.21(-0.4) cm long × 0.1-0.16(-0.26) cm broad × 0.3-0.38 cm wide, four flowers visible in the primary spiral and 5- 8 in the alternate spiral, one locule evident, hexagonal; stigma 1-1.5(-1.8) mm in the major diam.; stamens 1.1- 1.8 mm long × 0.5-0.8 mm wide, hyaline, no divaricated, basifixed. Berries not observed.

Etymology. The epithet refers to the whitish color on the adaxial blade surface.

Distribution and habitat. This species is only known from the Central Andes in the Department of Caldas, in the National Natural Park Selva de Florencia in corregimiento de Florencia (Samaná), on forest edges close to vereda San Lucas. The elevational range of the species is between 1200 and 1400 m a.s.l.

Phenology. Specimens were found flowering in July and August.

Additional specimens examined.

Stenospermation albifolium. COLOMBIA.

Depto. Caldas. Samaná, municipio de Florencia, PNN Selva de Florencia, camino entre Coleaderos y San Lucas, 1400 m s.m., 6-VII-2017 (fl), N. Castaño-Rubiano 2209 (paratype CUVC).

Discussion. Stenospermation albifolium is a species with a terrestrial habit, elliptic blades whitish abaxially, conspicuous primary lateral veins, angle of the insertion of the spate at the peduncle obtuse, long stipitate inflorescences, white and naviculiform spathe, and slightly tapered toward the apex spadix, which become capitated or expanded before male anthesis; spathe with 4 visible flowers in the principal spiral and 5- 8 in the alternate spiral. Due to its whitish leaves beneath, this species could be confused with S. glaucophyllum (^{Croat et al., 2007}: 301) (see diagnosis).

Stenospermation melidae Castaño-Rubiano & Sierra- Giraldo, sp. nov. TYPE: COLOMBIA. Depto. Caldas. Munic. Samaná, corregimiento de Florencia, PNN Selva de Florencia, camino hacia la vereda San Lucas, cerca de Coleaderos, 5° 31’ 16.0’’ N, 75° 03’ 25.1’’ W, 1400 m a.s.l., 24-IV-2018 (fl.), N. Castaño-Rubiano 2208 (holotype: FAUC-37710!; isotypes: HUA!, CUVC!, COL!). Figs. 1, 4, 5.

Diagnosis. Similar to S. amomifolium (Poepp.) Schott due to its pink infructescence, but differs in having lanceolate leaves drying olive- green (vs. obovate leaves drying black), and long pendent inflorescences 12-15.8 cm long, 0.62-0.77 cm diam. with a portion of the apex of the inflorescence lacking some flowers (vs. almost erect and shorter inflorescences, 3.6 -5.5 cm long, 0.69-1.5 cm diam. with all spadix covered by flowers).

Description. Epiphyte. Stem with internodes 7-19 mm long, 7-25 mm diam.; cataphylls persistent, intact, with two ribs, 12.8-29.7 × 11.5-30. 8 mm; petioles 12 -34.6 cm long × 0.17- 0.61 cm diam.; geniculum concolorous, 6.2 -28.3 mm long, 2.2-6 mm diam.; sheath 11.5-23 × 0.41 -1.25 cm, covering (70-)90-100% of the petiole, apex auriculate on one side, acute on the other, entire margin. Leaves erect; blades 9-36.7 × 5-12.4 cm, lanceolate, one side broader than the other, cuneate at the base, acuminate at apex, coriaceous; upper surface glossy, light green when fresh, drying olive-green; lower surface somewhat gloss, greenish-white when alive, drying light brown; midrib sunken above, U-shaped below, paler than surface; primary lateral veins inconspicuous on both surface, ca. 35 -40 pairs, slightly arched, starting from an angle of 45-50°; tertiary veins less prominent than primary lateral veins, slightly raised on both surfaces surface; marginal band narrow (0.63-1.5 mm), bent towards the underside.

Fig 4 Stenospermation melidae. A, habit. B, sheet. C, apex of the sheet. D, spadix. E, sterile flowers and naked portion of the spadix. F, transversal view of flower. G, longitudinal view of stamens and flower. H, stamen. I, longitudinal view of ovary. J, seed. Drawn by Eileen Muñoz, based in: N. Castaño-Rubiano 2208, J. A. Sierra Giraldo & J. A. Orozco Agudelo 2047 and pictures. 

Fig. 5 Stenospermation melidae. A, habitat. B, infructescence and blade. C, inflorescence and blade. D, apex of the sheet. E, infructescence and sterile flowers. F, seeds. Color version at https://www.ojs.darwin.edu.ar/index.php/ darwiniana/article/view/1134/1316 

Inflorescences erect, eventually cernuous; peduncles 33.5-57 cm long, 0.22-0.41 cm diam., 100% sheathed by the preceding sheath; spathes (14-)16-21 × 1.2-5.92 cm, papyraceous, ensiform-linear, meeting on the peduncle in at an acute angle (45°), white, glossy, long attenuated at the apex, with a long portion of the spathe free from the spadix, deciduous; stipe (1.0-)1.3-2.0 cm long, 0.2-0.4 cm diam.; spadix 12-15.8 cm long., 0.62-0.77 cm diam., white, slightly tapered toward the apex, with a sterile portion of flowers, some portions of the rachis lacking flowers; flowers 0.3-0.4 cm long × 0.2-0.36 cm broad × 0.2-0.3 cm wide, 3-4 visible in the principal spiral and 5-8 in the alternate spiral, two locule evident, hexagonal, those near to the apex non-functional; stigma 0.1-0.5 mm in the major diam.; stamens 2-3 × 0.5-1 mm, hyaline, no divaricated, basifixed, inserted after male anthesis. Berries 4-6 mm long × 2-5 mm broad × 4-5 mm wide, pink in the stylar zone when fresh; seeds 1.8-2 × 0.8-1 mm, 6-8 per locule, cylindrical, green, with white aril when alive.

Etymology. The epithet honors the memory of Mélida Restrepo de Fraume (1935-2010), who was a forerunner of the study of botany in the Caldas Department.

Distribution and habitat. This species is endemic to Colombia, known from three localities in the Central Andes in the Departments of Caldas and Antioquia. The first locality, on the edge of Río San Lucas (Florencia, Samaná), the second locality on the edge of Río Manso (Berlin, Samaná) and the third in Vereda El Porvenir (Carmen del Viboral, Antioquia). The elevational range of the species is between 653 and 1523 m a.s.l, at river borders.

Phenology. Specimens with flowers and fruits were found in April, July, August, October, and December.

Additional specimens examined.

Stenospermation melidae. COLOMBIA. Antioquia. Carmen del Vivoral, Vereda El Porvenir, alrededores de la escuela a lo largo de quebrada Melcocha 1087 m s.m., 1-XII-2016 (fl), H. Mendoza

J. Aguirre 19444 (FMB). Caldas. Samaná, corregimiento de Florencia, camino a la cuenca Las Mercedes, 1523 m s.m., 6-X-2017 (fl, fr), N. Castaño-Rubiano 2104 (paratype CUVC, HUQ); Vereda San Lucas, bosques aledaños al río San Lucas, 1204 m s.m., 4-VIII-2021 (fl), N. Castaño-Rubiano et al. 2356 (paratype HUAZ); corregimiento de Berlín, localidad de Piedras verdes, a orillas del río Manso, 778 m s.m., 26-VII-2019 (fl, fr), N. Castaño Rubiano et al. 2271 (paratype FAUC, UIS); Vegetación secundaria alta, cerca de la Parcela 13 Isagen-Ucaldas (CV-VSA1), 812 m s.m., 15-VIII-2022 (fl) J. A. Sierra Giraldo & J. A. Orozco Agudelo 2047 (paratype FAUC).

Discussion. Stenospermation melidae has an epiphytic habit, long distichous leaves, elongated, pendent and stipitate inflorescences, having a 45° angle in the insertion of the spate at the peduncle, a slender white spathe, and slightly tapered toward the apex spadix, with 3-4 flowers visible in the principal spiral and 5-8 flowers in the alternate spiral. Additionally, the spadix has an apical portion of sterile flowers and even a portion of the axis lacking flowers, the infructescence is pink, and the berries contain six cylindrical seeds. Due to its pink infructescence, this species might be confused with S. amomifolium (see diagnosis).

Stenospermation selvaflorensis Castaño-Rubiano, L. Ibañez & Zuluaga sp. nov. TYPE: COLOMBIA. Depto. Caldas. Munic Samaná, corregimiento de Florencia, PNN Selva de Florencia, microcuenca La Selva, 05° 31’ 16” N, 75° 3’ 25.1” W, 1400 m s.m., 22-II-2018 (fl.), N. Castaño-Rubiano 2193 (holotype: FAUC-37711!; isotypes: COL!, CUVC!, HUA!). Figs. 1, 6, 7.

Diagnosis. Similar to S. gentryi Croat, S. longifolium Engl., S. longispadix Croat, S. multiovulatum (Engl.) N. E. Br. and S. popayanense Schott, due to its large size (50-100 cm tall) and the almost erect inflorescences. All similar species have cylindrical inflorescences rounded at the apex and epiphytic habit, meanwhile, S. selvaflorensis has cylindrical, tapered at apex inflorescences and terrestrial habit. It is also similar to S. weberbaueri Engl., because of the cylindrical and tapered at apex spadices, but differs by the terrestrial (vs. terrestrial to epiphyte habit), the bigger size in general, and the erect inflorescence with exserted stamens during male phase of anthesis (vs. pendent inflorescences with inserted stamens at male phase of anthesis).

Fig. 6 Stenospermation selvaflorensis. A, habit. B, spathe. C, blade. D-E, sheet apex. F, spadix. G, close up spadix apex: note its acute shape. H, transversal view of the flower. I, longitudinal view of the flower. J, stamen. K, longitudinal view of the fruit. L, longitudinal cross section of the fruit. M, seed. Drawn by Eileen Muñoz, based in: N. Castaño-Rubiano 2193 and pictures. 

Fig. 7 Stenospermation selvaflorensis. A, habitat. B, habit. C, sheet apex. D, inflorescence with spate. E, spadix in male anthesis. F, detail of spadix apex and stamens. G, infructescence. H, seeds. Color version at https://www.ojs. darwin.edu.ar/index.php/darwiniana/article/view/1134/1316 

Description. Terrestrial 50-100 cm tall. Stem with internodes 20- 52 mm long, 3.5-11 mm diam. when fresh, 12-32 mm long, 4.7- 10 mm diam. when dry; cataphylls persistent, intact, 3.03-5.05(-7.07) × 0.6-0.81 cm when dry; petioles 13-28.1 cm long, 0.2-0.32 cm diam. when fresh, 14.9-25.8 cm long, 0.18-0.32 cm diam. when dry; geniculum concolorous, 7-21.2 mm long, 1.8 -3.3 mm diam. when dry; sheath 12.1-20.3 × 0.3-0.5 cm, covering (70%-)80% of the petiole (up to 90% in those preceding inflorescence), apex rounded on one side, acute on the other, entire margin. Blades 15- × 4.7-8.6 cm when fresh, 13.7-30.2 × 4.0- 74(-2.5) cm when dry, lanceolate, attenuate at base, acuminate at apex, coriaceous; upper surface glossy, somewhat cover with pale lineations, dark green when alive, drying olive-green; lower surface somewhat glossy, greenish-white when fresh, drying brown; midrib flat above, prominent and U-shaped bellow; primary lateral veins inconspicuous on both surfaces, ca. 31-49 pairs, arched, starting from an angle of 50°; tertiary veins less prominent than primary lateral veins; marginal band narrow (1 mm), bent towards the underside. Inflorescences erect, eventually a little cernuous; peduncles 17-39 cm long, 0.3-0.52 cm diam. when fresh, up to 50% sheathed by the preceding sheath; spathe 6.2-9.7 cm long × 4.0-5.9 cm wide. when fresh, papyraceous, naviculiform, meeting on the peduncle in a obtuse angle, white to pale withe-yellowish, matte, cuspidate at the apex, deciduous; stipe 0.4-0.7 cm long, 0.4-0.97 cm diam. when fresh, 0.6-0.13 cm long, 0.18-0.3 cm diam. when dry; spadix 5.5-9.7 cm long, (0.4-)0.8-1.5(-0.23) cm diam. when fresh, 4.36- 1 cm long, 0.6-0.8 cm diam. when dry, white to cream, cylindrical and tapered at the apex, apical flowers sterile. Flowers 0.21-0.35 cm long × 0.19-0.31 cm broad × 0.3-0.4 cm wide, visible in the principal spiral and 4 in the alternate spiral, one locule evident, hexagonal, those near to the apex non-functional; stigma 22-0.43 mm in the major diam. when fresh; stamens 3-4 × 0.8-1 mm, hyaline, divaricated, exerted and persistent after male anthesis. Berries 4-6 mm long × 4-5 mm broad, 4-6 mm wide, white, when fresh, 1.18-4.1 mm long × 2.37-4.23 mm broad × 3 -3.5 mm wide when dry; seeds 1.7-2.32 × 1-1.71 mm, (1-)6-8 per locule, ellipsoid, flattened towards the raphe, beige with white aril when fresh.

Etymology. The epithet selvaflorensis is in honor of Parque Nacional Natural Selva de Florencia, one of the most important protected areas in the Central Andes, an important relict of biodiversity around a coffee zone in Colombia.

Distribution and habitat. This species is endemic to Colombia and is only known from the Central Andes in the Department of Caldas, in the PNN Selva de Florencia in the corregimiento de Florencia (Samaná), at an elevation of 1700 m. a.s.l., in clearings and forest edges.

Phenology. We found specimens flowering throughout the year, but with a peak of productivity in May and January, with a low number of inflorescences/infructescences, and a low rate of fruit productivity.

Additional specimens examined Stenospermation selvaflorensis. COLOMBIA.

Caldas. Samaná, Florencia, PNN Selva de Florencia, microcuenca La Selva, 1700 m s.m., 22-II-2018 (fl), N. Castaño-Rubiano 2192 (paratype FAUC, HUAZ, HUQ).

Discussions. Stenospermation selvaflorensis is a large terrestrial plant with erect stems, with sclerenchyma fibers in the cataphylls that causes itchiness on contact. Mainly erect inflorescences (eventually cernuous at apex), stipitate spadices, and a white to pale white-yellowish spathe, very fitted to the spathe even in anthesis, but no persistent. The inflorescence is cylindrical and tapered at the apex, has 6 flowers in the principal spiral and 4 in the alternate spiral, and sterile apical flowers. The stamens are white hyaline and emerge from the surface of the flowers during the male phase of anthesis. The berries are white and contain six to eight reniform seeds. This species can be confused with S. gentryi, S. longifolium, S. longispadix, S. multiovulatum and S. popayanense (see diagnosis).

Key to Stenospermation morphologically close to the new species in Colombia

1. Inflorescences cylindrical with rounded or truncate apex 2

1. Inflorescences slightly tapered or cylindrical with tapered apex 8

2(1). Leaf glaucus beneath, with a waxy appearanceS. glaucophyllum

2. Leaf paler beneath but not glaucus 3

3(2). Primary lateral veins prominent 4

3. Primary lateral veins not prominent or inconspicuous 5

4(3). Blade oblong-elliptic to narrowly oblong-elliptic, acute at base, Inflorescence stipitateS. longifolium

4. Blade oblong-elliptic, cuneate to attenuated at base, Inflorescence subsessileS. longispadix

5(3). Spathe persistentS. gentryi

5. Spathe deciduous 6

6(5). Thick inflorescences, 12-17 cm long x 1.1-1.5 cm diameterS. multiovulatum

6. Slender inflorescences, 4,5-11 cm long x 0.4-0.6 cm diameter 7

7(6). Leaf sheath with scarious margin, truncated by one side, acute for the otherS. popayanense

7. Leaf sheath with entire margin, shortly free at apex, rounded by one side, acute for the otherS. angustifolium

8(1). Pink Infructescences 9

8. Orange, yellow or white Infructescences 10

9(8). Pendent inflorescence, slightly tapered toward apex, with a portion of the axis without flowers, apical flower

truncated or flatS. melidae

9. Erect inflorescence, cylindrical at base and medial zone, tapered at apex, axis covered completely by flowers, apical

flower conicalS. amomifolium

10(8). Epiphytic habitS. weberbaueri

10. Terrestrial habit 11

11(10). Leaf glaucous beneath, blades two times longer than broadS. albifolium

11. Leaf paler beneath but not white, blades three to four times longer than broadS. selvaflorensis