Chlorospatha minima Zuluaga & Munoz-Castillo, 2019

Munoz-Castillo, Allison, Guevara-Ibarra, Leonardo, Clavijo, Laura & Zuluaga, Alejandro, 2019, Two new species of Chlorospatha section Orientales (Araceae) from western Andes in Colombia, PhytoKeys 135, pp. 21-34 : 21

Chlorospatha minima Zuluaga & Munoz-Castillo sp. nov. Figs 1 , 2 , 3 , 4

Type.

COLOMBIA. Valle del Cauca: municipio Dagua, corregimiento El Queremal, old road Cali-Buenaventura, 6 km from El Queremal, 3°33'45.6"N, 76°45'27.1"W, 1050-1100 m, 20 May 2017, A. Zuluaga, L. Guevara, M. Llano & A. Muñoz 1645 (holotype: CUVC!; isotypes: COL!, MO!)

Diagnosis.

Chlorospatha minima can be distinguished from other species in section Orientales by its overall small size (less than 30 cm tall), smooth adaxial leaf surface, 1-2 inflorescences per axil, and spadix 20.4-22.8 mm long. Additionally, it differs from C. silverstonei sp. nov., the other species of this section in the western slopes of the Andes, by having three collective veins (vs. two in C. silverstonei sp. nov.), and the primary lateral (secondary) and minor veins glabrous on the abaxial surface (vs. scale-like indument).

Terrestrial herb, 10 –25(– 30) cm tall; stem subterranean, decumbent, with cataphylls quickly deciduous; internodes 6.6-7.4 × 5.4-7.8 mm, drying matte, dark brown; cataphylls brownish green, 5.2-6.2 cm long, acuminate at apex, drying matte, reddish brown. Leaves 2 to 5, erect-spreading; petioles 8.3-28.2 cm long, fleshy, glabrous, semiglossy, green with faint darker transverse markings, drying matte, dark brown, sheathed 5.2 –9.4(– 12.0) cm or (1/5 –)1/3– 1/2 of its total length, rarely more than 1/2; sheath decurrent onto the petiole apex; free portion of the petiole 0.6-3.7 mm diam. midway; blades broadly triangular-ovate, inequilateral, 5.8 –14.2(– 16.3) × 2.6-10.1 cm, 1.5 to 2.2 times longer than wide, weakly hastate at base, acuminate at apex, usually slightly broader across anterior lobe than at base, not constricted at petiole insertion, glabrous, conspicuously discolor, distance tip to tip across posterior lobes 2.2-9.2 cm wide; both surfaces smooth, glossy, drying semiglossy; abaxial surface with several layers of cells forming a reticulum, 0.3 to 0.4 mm diam.; anterior lobe 5.1-11.9 × 2.6-10.1 cm, 1 to 2 times longer than wide, 2.2 to 5.7 times longer than posterior lobe, wider near petiole insertion, rarely asymmetrical; posterior lobes directed toward base, 0.9-4.6 (-5.2) × 0.8-4.4 cm, 0.7 to 1.4 times longer than wide, narrowly rounded to obtuse at apex, slightly broader at petiole insertion, ± symmetrical, sinus parabolic to spathulate; midrib and major venation usually darker than the surface, round-raised and drying ± flattened abaxially; primary lateral veins 3, rarely 4, per side, arising at 30°-60°, rarely 70°, straight to weakly curving towards the margin; secondary veins abaxially sunken, drying visible and darker than the surface, the primary lateral and minor veins glabrous on the abaxial surface; 3 collective veins that originate from first, second and third basiscopic veins, respectively, ± parallel to margin; basal veins coalescent into a prominent posterior rib, 1 –2(– 3) acroscopic, 2 –3(– 4) basiscopic veins; minor veins slightly visible abaxially. Inflorescences erect, 1 to 2 per axil; cataphylls of inflorescence not visible outside the sheath; peduncle held within the sheath, 34.0 –51.5(– 76.0) × 0.4-1.2 mm, drying dark brown to black; spathe erect (all measurements for the spathe and spadix made from spirit material), 27.0-29.8 mm long, apiculate at apex, 6.6-7.0 mm (1.1 to 1.3 times) longer than spadix; spathe tube green or pale green on outer surface, rarely maroon-tinged, 10.0-12.9 × 4.2-4.3 mm, drying dark brown to black on outer surface; spathe blade maroon-tinged, with green veins on outer surface, green on inner surface, drying dark brown or black, ca. 16.9 mm long, erect after anthesis, then marcescent; spadix erect, 20.4-22.8 mm long, sessile, adnate basally to the spathe for 2.3-3.1 mm (1/5 to 1/3 of the length of pistillate portion); pistillate portion light green, 8.3-8.6 × 2.0 mm; pistils ca. 1.3 mm diam.; stigma light green, sessile, ca. 0.4 mm diam.; fertile staminate portion white, 11.2-12.9 × 2.8-3.0 mm, cylindrical, rounded at apex, drying whitish brown; synandria ca. 1.3 mm diam., coherent; sterile portion white, 2.2-2.5 × 2.7 mm, wider at apex, drying whitish brown; sterile flowers with straight borders, 1.2 mm diam. (viewed from above). Infructescence (measurements made from spirit material) erect or pendent, brown, ca. 25.5 × 8.0 mm, drying mate, dark brown on outer surface; berries green, 2.3-3.9 mm diam.; seeds white, (6-)20 to 24 per berry, 1.2-1.5 × 0.7-0.9 mm, ovoid to ellipsoid, longitudinally striate, minutely white-strophiolate.

Etimology.

The epithet minima refers to the small size of this species, less than 30 cm tall, the smallest in the genus.

Distribution and ecology.

Chlorospatha minima is endemic to the western slopes of the Colombian Andes in the department of Valle del Cauca. It has been found only in one locality on the old road Cali-Buenaventura at 1000 m, inhabiting humid forest and growing close to a waterfall ( Fig. 1 ).

Conservation status.

Despite more than four years of extensive field work, Chlorospatha minima is known only from one population located outside the Farallones de Cali National Natural Park, in an area frequently visited by tourists. Because the estimated extent of occurrence is less than 100 km2, the only population known has less than 100 individuals, and the quality of habitat is declining, C. minima could be assessed as Critically Endangered, according to the IUCN criteria ( IUCN 2012, 2017).

Discussion.

Chlorospatha minima belongs to section Orientales , characterized by having a stylar region lacking a mantle ( Fig. 2B ). However, all species in section Orientales , as recognized by Croat and Hannon (2015), are endemic to the eastern slopes of the Ecuadorian Andes, whereas C. minima and C. silverstonei sp. nov. (also described here) are endemic to the western slopes of the Colombian Andes. Chlorospatha minima is similar to C. silverstonei (see discussion under this species), C. longipoda (K.Krause) Madison, C. hannoniae Croat, and C. boosii Croat & L.P.Hannon, but it differs from these four species in having an overall smaller size, less than 30 cm tall (vs. 30-60 cm). Additionally, C. minima is the only species with smooth adaxial leaf surface (vs. quilted or bullate) ( Fig. 3 ), cataphylls of inflorescence not visible outside the petiole sheath, and 1 to 2 inflorescences per axil (vs. 1 to 7) (Table 1 ).

Chlorospatha minima differs from C. longipoda in having leaves broadly triangular-ovate vs. narrowly ovate or ovate-elliptic, base of blade slightly hastate vs. subcordate to subsagittate, and (6)20-24 seeds per berry (vs. 7-8). It differs from C. hannoniae in having leaves weakly hastate at base vs. sagittate or subsagittate, apex of spathe apiculate vs. cuspidate, and erect spadix vs. slightly curving forward. Finally, C. minima differs from C. boosii in having 2-5 leaves that are held erect (vs. 8 to 12 leaves) (Table 1 ). Also, in both species described here, we observed several layers of apparently dead cells on the abaxial surface forming a reticulum visible on dried specimens ( Fig. 2 F–G , 2 M–N ). This is not mentioned on the description of other species of section Orientales ; therefore this could be a potential diagnostic character.

Specimens examined.

COLOMBIA. Valle del Cauca: municipio Dagua, corregimiento El Queremal, 3°33'45.6"N, 76°45'27.1"W, 1159 m, 17 Mar 2018, Zuluaga et al. 2328 (CUVC!).

Figures

Figure 1. Distribution map of Chlorospatha minima (star) and C. silverstonei (circle).

Figure 2. Inflorescence and leaf characters of Chlorospatha minima and C. silverstonei. A-I C. minima J-O C. silverstonei A inflorescence B female flowers C male flowers D sterile flowers E infructescence F adaxial blade surface, note the reticulum of cells in the peeling of abaxial surface G abaxial blade surface H primary lateral and minor veins glabrous on abaxial surface I seed J inflorescence K female flowers L male flowers M adaxial blade surface, note the layers of cells N abaxial blade surface O primary lateral and minor veins with scale-like indumentum on abaxial surface. (Photographs by Juan Felipe Ortega and the imaging laboratory at the Biology graduate program at Universidad del Valle).

Figure 3. Main morphological characters of Chlorospatha silverstonei and C. minima. A, B, E C. silverstonei C, D, F, G C. minima A adult plant B abaxial blade surface C abaxial blade surface D adult plant E cataphyll and inflorescence in post anthesis, note spathe acuminate and longer than the spadix F Inflorescence in anthesis (right) and post-anthesis (left) G shoot, showing young infructescence with deciduous spathe blade and young inflorescence.

Figure 4. Illustration of Chlorospatha minima A adult plant with inflorescence B infructescence C inflorescence at anthesis D inflorescence on post-anthesis E abaxial surface of leaf blade; note reticulate venation and collective veins F upper view of male flowers G upper view of sterile flowers H upper view of female flowers I seed. (Drawn by Eileen Munoz from the holotype A. Zuluaga et al. 1645).