Paepalanthus huancabambensis Hensold, 2016

Hensold, Nancy, 2016, The Andean Paepalanthus pilosus complex (Eriocaulaceae): a revision with three new taxa, PhytoKeys 64, pp. 1-57 : 26-28

3. Paepalanthus huancabambensis Hensold sp. nov. Figures 3F , 9

Diagnosis.

Plants forming loose cushions or mats; leaves blue-green, pilose above, older leaves strongly costate below; peduncle sheaths 25-30 mm, very lax, and strongly exsert from the leaf mat, the involucral bracts dark brown, the heads with over 20 flowers; pistillate flower petals spatulate, pilose; nectaries dark red-brown and rigidulous, those of the male flowers equaling the corolla sinuses.

Type.

PERU. Piura: Huancabamba, Jalca de Chiguelas , 5°8.2'S, 79°23.6'W, 3082 m, 19 Oct 2001, A. Sagástegui et al. 16799 (holotype: F; isotype: HAO) .

Description.

Plants short-caulescent, with erect actively growing shoots to 4 cm, densely leafy, branching to form rounded mats. Leaves subulate, acute, 13-22 mm long × 1-2 mm wide at midpoint, tip cuspidate to apiculate, densely pilose to villous above with appressed to spreading white tuberculate hairs, upper margin eciliate, lamina dark blue-green, mature leaves prominently 3-5-costate below. Inflorescences solitary and terminal, soon overtopped by one or two erect lateral shoots which may flower in rapid succession, so that peduncles superficially appear fascicled. Peduncles 6.0-11.5 cm long at anthesis, perhaps continuing to elongate into fruiting, with peduncle of previous season up to 15 cm observed on same plant, ca. 3-costate, densely subappressed-villous especially above, with a dense sericeous collar of trichomes subtending involucre. Peduncle sheaths 25-30 mm, much surpassing the leaves, and strongly surpassing the leaf mat, scarious, very lax, nearly glabrous except for the tufted apex, the lamina cucullate, enclosing the bud when young and then splitting broadly into two or three triangular segments. Capitula 4-6 mm, depressed-hemispheric. Involucres subequaling flowers at anthesis, and opening broadly at maturity; involucral bracts 2-3-seriate, the outer bracts triangular-ovate, greenish to uniformly dark brown, shaggy-ciliate on margins and villous in two submedial bands. Floral trichomes obtuse to clavate, strongly tuberculate. Flowers ca. 20-24 per capitulum, the pistillate flowers peripheral, the staminate central, with 14-18 pistillate flowers to 6 staminate flowers (in two capitula sampled). Receptacle sparingly long-pilose with brownish hairs. Receptacular bracts subequaling flowers, linear-subspatulate, the apex slightly cucullate, pubescent as sepals, the base sharply carinate. Pistillate flowers: Pedicels 0.3-0.45 mm long, fine and membranous. Sepals broadly obovate-spatulate to subtruncate at apex, sometimes weakly cymbiform, 1.55-1.65 mm long × 0.65-0.8 mm wide at middle, 0.15-0.2 mm wide at base, blackish-brown, short-ciliate (apical cilia to 0.17 mm) along upper margin, and appressed-long-pilose in two bands flanking the upper dorsum, the basal half of the midrib hygroscopically thickened, spadiceous-brown in fruit, and recurving when dry, the broad upper half of the sepal remaining chartaceous, erect; sepals detaching from fruit on dispersal. Petals spatulate, obtuse, brownish at tip, 1.25-1.35 mm long, the widest in a flower ca. 0.65 mm wide, ca. 2.2 times longer than wide, bearing scale-like staminodes at base, densely long-pilose with long tuberculate hairs on abaxial upper half except for midvein, also tufted subapically within, the hairs enfolding the style branch, petals not thickening in fruit, dispersed with fruit. Gynoecium with style base 0.35 mm long; nectaries ca. 0.7 mm long, dark red-brown, penicillate to subclavate-infundibular, with fringe of colorless stiff-walled papillae at mouth, these rigidulous and maintaining shape after anthesis; style branches 0.85 mm long, thick and dark red-brown, non-involute. Only two slightly misshapen seeds seen, 0.6-0.63 mm long, pinkish to red-brown, the pseudotrichomes weak. Staminate flowers: Pedicels 0.35-0.4 mm, membranous, nearly glabrous. Sepals 1.6-1.7 mm × 0.5-0.6 mm, spatulate to obrhombic or subtruncate, color and pubescence as in the female flowers, narrowed toward base and shallowly fused. Corolla 1.8 mm long; the anthophore 1.15 mm long, comprising ca. 65% the length of the corolla, grading from 0.15 mm wide at base to 0.35 mm wide at apex; the tube 0.65 mm long including well-defined brownish-tinged lobes. Filaments brownish-tinged above; exsert not more than 0.3 mm beyond lobe tips, anthers persistent, cream to light brownish. Nectaries equaling corolla sinuses.

Phenology.

Collected in flower May, September, October.

Distribution.

Endemic to Peru, Piura, Cordillera de Huancabamba, District Carmen de la Frontera (Fig. 8 ).

Habitat.

Grass páramo (or jalca), probably of anthropic origin, and "burnt cloud forest, growing under Pteridium aquilinum " (Weigend & Dostert 98/252). Elevation ca. 2900-3000 m.

Conservation status.

Assessed as Critically Endangered, according to IUCN Criteria B1ab(iii) ( IUCN 2014). Known from one locality in an unprotected area subject to deforestation, subsistence agriculture, and tourism.

Notes.

Paepalanthus huancabambensis is similar in habit and dimensions to Paepalanthus dendroides , but differs by its very lax, elongate peduncle sheaths well exsert from the leaf mat, and the large capitula with more flowers. It also differs in the dark blue-green leaf color, compared to the consistently pale green leaves of the widespread Paepalanthus dendroides , and preliminary anatomical study distinguishes it from that species by the presence of adaxial vein buttresses (bundle sheath extensions) in leaf median section. The broadly spatulate densely pilose female petals are similar to those of Paepalanthus dendroides . However, the longer style base, the dark rigidulous nectaries with stiff colorless papillae fringing the rim, and the size of the nectaries relative to the corolla tube in the male flowers all suggest Paepalanthus pilosus .

Except for the lax peduncle sheaths, this species lacks any strong distinctive features of its own but its mixture of critical characters prevent it from being easily placed in any related species, and do not immediately suggest hybrid origin. It is endemic to the Cordillera de Huancabamba near the border of Peru and Ecuador in the western part of the Andean chain. Notably, in the same vicinity are also found an atypical form of Paepalanthus pilosus (Cano 16840, discussed under Paepalanthus pilosus var. pilosus ), and at higher elevations the only known populations of Paepalanthus lodiculoides from Peru and Ecuador.

Additional specimens examined.

PERU. Piura: Huancabamba, Cordillera Chinguela ( Sapalache el Cármen), 2900 m, 15 Sept 1981, Sagástegui et al. 10225 (HUT n.v., MO), Huancabamba-Sapalache, waterfall E of Chorro Blanco E of Sapalache, growing under Pteridium aquilinum in burnt cloud forest, 2650-2930 m, 19 May 1998, Weigend & Dostert 98/252 (M, USM n.v.)

Figures

Figure 3. Vascular bundle morphology, adaxial side up. A Paepalanthus caryonauta B Paepalanthus pilosus var. pilosus C-E Paepalanthus dendroides F Paepalanthus huancabambensis midvein, with bundle sheath extensions. (A Valenzuela 8117 B Barbour 3427 C Leon 2683 D-E Leon 2243. F: Sagastegui 16799 D-F Mesophyll darkened for contrast.)

Figure 8. Distribution of Paepalanthus dendroides, Paepalanthus huancabambensis, and Paepalanthus lodiculoides.

Figure 9. Paepalanthus huancabambensis (Sagastegui 16799). A Habit B Capitulum, anthesis C Staminate flower, anthesis D-I Pistillate flower D Whole flower E Petal, adaxial F Petal, abaxial G Gynoecium, juvenile H Sepal, anthesis I Gynoecium and one petal, young fruit.