Stenomesson ecuadorense Meerow, Oleas & Jost, 2015

Meerow, Alan W., Jost, Lou & Oleas, Nora, 2015, Two new species of endemic Ecuadorean Amaryllidaceae (Asparagales, Amaryllidaceae, Amarylloideae, Eucharideae), PhytoKeys 48, pp. 1-9 : 1-3

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Stenomesson ecuadorense Meerow, Oleas & Jost

sp. nov.

Stenomesson ecuadorense Meerow, Oleas & Jost sp. nov. Fig. 1 View Figure 1


Stenomesson ecuadorense (Fig. 1 View Figure 1 ) appears closely related to the Peruvian Stenomesson miniatum (Herb.) Ravenna (1978; Fig. 2A) and Stenomesson campanulatum Meerow (1985; Fig. 2B) by flower color and adherence of the staminal corona to the floral tube, consisting of six long teeth interposed between the free filaments, but differs from them by the moist habitat, occurence on limestone and relatively low elevation (Table 1 View Table 1 ). Stenomesson miniatum has an urceolate corolla. Stenomesson campanulatum has a non-patent limb and long-exserted stamens. The perianth of Stenomesson ecuadorense has flaring tepals as does Stenomesson miniatum , but is long campanulate in morphlogy.


ECUADOR: Zamora-Chinchipe, Tapala, on limestone cliffs above Río San Luis, near its confluence with the Río Numbala; 4°32.478'S, 79°03.985'W, ca. 1295 m elevation, 18 March 2006 (observed in flower and fruit; specimens made from flowering cultivated plants 10 Apr 2012), Lou Jost 7949 (Holotype: QCA!, Isotypes: QCNE!, HUTI!, MO!, NA!, NY!).


Geophytic, hysteranthous, perennial from tunicate bulbs. Bulbs globose to ovoid, offsetting readily, tunics brown, 2-4 cm diam, apically forming a neck 1-5 cm long. Leaves (Fig. 1A-C View Figure 1 ) 1-2 per bulb, glabrous, 18.5-30 cm long, tapering at base to a ca. 5 cm long hemiterete pseudopetiole; lamina lanceolate, sometimes slightly falcate, 14-14.5 × 1.8-3.0 cm wide at the middle, midrib inconspicuous adaxially, prominent abaxially, acute at apex, Royal Horticultural Society Color Chart (RHSCC, Royal Horticultural Society 1995) green 137A adaxially, 137D abaxially. Inflorescence scapose, 1-4 flowered, scape 25-30 cm tall, 3.7-3.9 mm diam, terete, glaucous, solid for most of its length with a narrow lumen apically, terminated by 2 marcescent ovate-lanceolate bracts enclosing the buds in the early stages of elongation, 20.9-21.6 mm long, 3.4-3.6 mm wide at base, 6 mm wide at middle, acute at apex. Flowers (Fig. 1D-G View Figure 1 ) pendulous via the spreading pedicels and curvature of the tube, 3.6-4 cm long from base of ovary to limb apex; pedicels 19-28 × ca. 0.5 mm. Perianth (Fig. 1D, E View Figure 1 ) actinomorphic, cylindrical proximally, distally campanulate, consisting of six tepals in two whorls, fused below the throat into a tube that is 2.7-3 mm diam, cylindrical, and green in the proximal 1-1.2 cm, constricting to 1.8-2.3 mm in its distal 3-4 mm before abruptly dilating to 7.3 mm and becoming orange (RHSCC orange red 33A). Limb of free tepals (Fig. 1F View Figure 1 ) spreading ca. 60° from the throat, 1.7-1.9 cm wide; outer tepals 9.8-10.6 mm × 4.8-5.6 mm (at middle), acute, with a white, papillose apiculum; inner tepals 7.5-8.5 mm long, 6.5-7 mm wide, minutely apiculate. Stamens joined at base into an inconspicuous membranous staminal corona in the form of six 0.8-1.0 cm long lanceolate, acute teeth, fused to the perianth tube except for the apical 1.0 mm of each tooth (Fig. 1G View Figure 1 ), with the filaments inserted between; free filaments filiform, light orange for their proximal third, then white in their distal 2/3, 1.7-1.8 cm long, exserted ca. 1 cm beyond the limb; anthers 1.8-2 mm long, oblong, dorsifixed, introrse; pollen yellow. Style 3.5-3.7 cm long, exserted 5-6 mm past stamens, orange, fading to light orange distally; stigma obscurely tri-lobed, 1-1.4 mm wide. Ovary ellipsoid, ca. 6.7 mm long, ca. 3.2 mm wide, ovules 20 or more per locule, axile in placentation. Mature fruit (Fig. 1H View Figure 1 ) a trigonous, papery, tri-loculicidal capsule ca. 1 cm long and 1.5 cm wide; seeds numerous, papyraceous, flattened, shortly obliquely winged, with a dark brown phytomelanous testa.

Distribution and ecology.

Stenomesson ecuadorense is so far only known from the type locality in southern Ecuador (Fig. 1I View Figure 1 ) where it grows on what appear to be limestone cliffs above the Río San Luis, just below 1300 m. It was first found by LJ in 2006 and subsequently examined in the field by AM and NO in 2009. As so far known, the species is restricted to these cliffs where it grows in cracks, crevices and narrow shelves on the rock where pockets of humus accumulate. We estimate the population that we observed to consist of several hundred individuals. The full extent of occurrence is not yet known.


The species is named for the nation of Ecuador, to where it so far appears to be endemic.

Additional material examined.

ECUADOR: Zamora Chinchipe, same locality as type, 1254 m elev., 04°33'38"S, 79°04'39"W, flowering. 23 June 2014, Pérez A. J., et al. 7260 (QCA).


The genus Stenomesson Herb. (sensu Meerow et al. 2000) includes about 15 spp., and is primarily found in Peru, with only Stenomesson aurantiacum Herb. previously reported from Ecuador ( Meerow 1990). The genus usually occurs in seasonally dry, grassy vegetation or at the margins of cloud forest above 2000 m elevation, but is also found in Peruvian inter-Andean valleys below 2000 m ( Meerow and van der Werff 2004), and the loma formations along the coast of Peru. The new species, Stenomesson ecuadorense , is found below 1300 m elevation in relatively wet habitat.

Stenomesson ecuadorense appears closely related to Stenomesson miniatum (Peru, Bolivia; Fig. 2A View Figure 2 ) and Stenomesson campanulatum Meerow (Peru; Fig. 2B View Figure 2 ) by the orange flower color and fusion of the staminal corona to the floral tube, but differs from them (Table 1 View Table 1 ) by the unusual limestone habitat and relatively low elevation. Stenomesson miniatum has an urceolate corolla, and is always found above 2000 m in elevation to as high as 3500 (unpubl. herbarium data). Stenomesson campanulatum has a non-patent limb and long-exserted stamens ( Meerow 1985). The perianth of Stenomesson ecuadorense has flaring tepals as does Stenomesson miniatum , but is long campanulate in morphology. It is only the second species of the genus (sensu Meerow et al. 2000) reported from Ecuador, and so far the only endemic one.