Pentagonia lanciloba Cornejo
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Authority
Cornejo, Xavier. 2010.
, a new species of Rubiaceae (Hippotideae) from northwestern Ecuador. Brittonia. 62 (1): 7-11. -
Family
Rubiaceae
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Scientific Name
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Description
Description - Unbranched pachycaul terminal stems subtetragonal, shoots glabrous or ±strigillose. ceolate, 2.2-4.5 cm, ±strigillose outside; terminal leaves with petioles 1-2.5 cm, ±strigillose; leaf blades deeply pinnatifid, drying thinly foliaceous to subchartaceous, obovate in general outline, 35-80 x 25- 50 cm, tapered and decurrent at the base, forming a wing 0.5-1.5 cm wide along midrib in the basal 10-20 cm, the main lateral veins 8-10 pairs, prominent beneath, the tertiary venation obscure, the adaxial surface glabrous throughout, the papillose, abaxial surface minutely hirtellous or strigose on the veins, the margin strigillose. Inflorescences axillary, congested cymose and conspicuosly bracteate, each bearing 5-50 flowers, the peduncle 5-12 x ca. 3 mm; floral bracts bright red, foliaceous, ovate to lanceolate, 20-35 x 8-20 mm, the apex long-acuminate to caudate; pedicels obscure, to 2 mm long, glabrous or ±strigose. Calyx regularly 5-lobed, foliaceous, 23-35 mm long, red, densely short- sericeous to strigose outside at base, gradually more sparsely strigose distally, glabrous or ±short-sericeous within, with colleters clustered in patches around the sinuses, the tube 5-8 mm long, the lobes ±equal, narrowly-lanceolate, 15-28 x 2-3 mm, apex tapering, divergent at anthesis. Corolla hypocrateriform, orange or rose to red, the tube 20-27 x ca. 5 mm, glabrous without at the base, grading to yellowish-tomentose (when dry) in the distal half to two thirds, the lobes 5, oblong-lanceolate, 4-5 x ca. 2 mm, divergent at anthesis. Stamens 5, ca. 10-12 mm long, attached in the lower third of the corolla tube, densely tomentose at the base, otherwise glabrous; anthers ca. 3 mm. Ovary subcylindric or obconic, ca. 3 x 3 mm, tomentose; style 11-16 mm, glabrous; stigma ca. 3 mm. Infructescences with persistent bracts; fruits ±globose to ellipsoid, 1 1-22 x 11-18 mm, ±obtuse at the apex, dark orange or bright red, densely strigose toward apex, crowned by a persistent calyx, the tube ca. 5 mm; seeds 4.3-4.7 mm.
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Discussion
Conservation status. - This species is apparently protected within two small privately owned properties and in the Reservas Mache Chindul and Awá of the National System of Protected Areas of Ecuador (SNAP). However, the known range of Pentagonia lanciloba, ca. 20,000 km2, is under pressure by deforestation. Therefore, this species is assigned to the category Near Threatened (NT) (IUCN, 2001)
Phenology. - Pentagonia lanciloba has been collected with flowers from March to September and with fruits in March, September, and October.
Etymology. - The specific epithet refers to the calyces with relatively long, narrowly lanceolate lobes, a unique character among the species of this genus with lobed or pinnate leaf blades (see Table I), and an unusual character among the remaining congeneric species with entire leaves.
Pentagonia lanciloba is easily distinguished by the combination of pinnatifid leaf blades with tapered and long-decurrent subsessile bases, red floral bracts with long-acuminate or caudate apices, calyces with lobes narrow- ly-lanceolate, 15-28 mm long, and orange to red corollas that are tomentose without (Fig. 1). Among the species of this genus, pinnatifid leaves with tapered, long-decurrent, subsessile bases are also present in P. tinajita, a species restricted to the Pacific lowlands of central Costa Rica to western Panama (Burger & Taylor, 1993). However, Pentagonia lanciloba is differentiated form the latter by the remaining characters mentioned above. Although in the original publication (Seeman 1854), P. tinajita was described as having red corollas, none of the ca. 20 flowering collections from Costa Rica and Panama that were studied had red corollas. This has also been confirmed by field observations of ca. 10 flowering individuals in the Osa Peninsula. Even if the orange to red corollas were not taken into account, P. lanciloba is morpholog- ically distinct enough in other features that it must be separated from the geographically disjunct P tinajita. Pentagonia lanciloba has been mistakenly reported as P. brachyotis (Standley) Standley (Foster et al., 1992), another treelet restricted to Panama and Colom- bia having pinnatifid leaves and red stipules and corollas. Pentagonia brachyotis, however, differs from P. lanciloba by its distinct wingless petioles with auriculate bases, calyces with shorter lobes (5-7 mm), ±ovate to oblong, and glabrate corollas. Characters differentiating P. lanciloba from P. tinajita and P. brachyotis as well as two other similar species, P. pinnatifida and P. alba, are presented in Table 1.