Leucheria cantillanensis Lavandero, 2020

Lavandero, Nicolas, Rosende, Benito & Perez, Maria Fernanda, 2020, Leucheria cantillanensis (Nassauvieae, Asteraceae), a new species endemic to Central Chile, PhytoKeys 169, pp. 99-117 : 99

Leucheria cantillanensis Lavandero sp. nov. Figures 3 , 4

Diagnosis.

Leucheria cantillanensis is similar to L. salina but differs in its flat lamina and chartaceous texture (vs. foliar segments perpendicular or oblique to the lamina axis and leathery texture) (Figs 5C, D , 6G, I ), conspicuously prominent venation, with the secondary and tertiary veins forming a raised pattern above and below the lamina (vs. non-prominent venation, with no raised pattern of veins in either side of the lamina) (Fig. 6G, I ), 27-30 flowers per capitula (vs. 40-60), purple anther apical appendages (vs. greenish-yellow) (Fig. 6D, F ). Leucheria cantillanensis is also similar to coastal forms of L. runcinata D.Don with white corollas, but it differs by its underground creeping rhizome with nodes and leaf scars and remnants of dry leaf petioles along the rhizome (vs. a lignified taproot with leaf scars concentrated at the base of the stem at the surface of the ground) (Fig. 6K, L ), entirely glandular indumentum in the leaves (vs. glandular on the adaxial side and glandular and lanate on the abaxial side) (Fig. 6H, I ), conspicuous prominent venation on both sides of the lamina (vs. inconspicuous and only midvein prominent on the abaxial side) and purple anther apical appendages (vs. greyish-blue) (Fig. 6E, F ).

Type.

Chile. Región Metropolitana: Provincia de Melipilla, entre el límite de Alhué y Melipilla, Reserva Natural Altos de Cantillana, 33°54'54.24"S, 70°58'43.57"W, 2007 m., 27 December 2019, fl. And fr., Lavandero 700 (holotype: CONC!; Isotype SGO!).

Description.

Perennial caulescent herb 15-30(-40) cm tall, decumbent, forming clumps of 5-6 aerial stems arising from the apex and nodes of the distal end of the rhizome. Rhizome dark brown, round, 10-15 mm wide, oblique to creeping, leafless below, but with remnants of dry leaf petioles, roots arising from the internodes. Roots dark brown, ca. 2 mm wide, round in cross-section. Stems purplish at the base, green at the top, 1.0-5.5 mm wide, simple or branching, round in cross-section, internodes up to 4 cm long, densely covered by glandular, capitate, (87-)115-180 µm long, multicellular (6-12-celled) trichomes with clear resin, fragrant, with pungent citric scent (same indumentum up to the corolla tube). Leaves dark green, alternate; basal leaves petiolate, semi-densely arranged at the base; petiole compressed, winged, vaginate, 2-2.5(-3.5) cm long; upper leaves sessile, amplexicaul, loosely arranged, gradually reduced in size towards the capitulescences. Lamina obovate, (10-)50-100(-140) × (5-)20-25(-35) mm; base attenuate, amplexicaul, apex mucronate; margin serrate, texture chartaceous, densely glandulous on both surfaces; pinnatisect to entire towards the tip; segments at the base entire, rarely 1(-2)-dentate, apex mucronate; segments in the middle (3-)4-6(-7)-dentate; apical segments fused, doubly dentate; venation conspicuously prominent, with the secondary and tertiary veins forming a raised pattern on both sides of the lamina, pinnate, semicraspedodromous, with primary vein ending in apical mucro, secondary veins either ending in second-order teeth or joining other distal secondary veins. Capitulescences a corymbiform cyme. Capitula 1-6 per stem, pedunculate, (0.5-)1.2-2.8(-3.6) cm long, homogamous, discoid. Involucres hemispheric 7.0-7.2 × 8.2-8.3 mm, two-seriate, alternate. A third series of Middle involucral bracts with intermediate characters between outer and inner Middle involucral bracts rarely present. Receptacle slightly convex, epaleate, glabrous. Outer Middle involucral bracts 5-6, green, lanceolate, concave on the inner face, 6.6-7.6 × 1.10-1.21(-1.36) mm, with 3 dark-green longitudinal stripes (including the midrib), apex ciliate, margin entire, texture leaf-like, abaxial lamina and margins densely covered by glandular trichomes, adaxial lamina glabrous. Middle involucral bracts rarely present, 1-2, green, lanceolate, concave to flat, with 6.5-7.0 × 1.08-1.19 mm, with 3 dark-green longitudinal stripes (including the midrib), apex ciliate, texture leaf-like to hyaline towards the margins, margin ciliate, rarely glandular, central portion of the abaxial lamina covered by glandular trichomes, hyaline lamina glabrous. Inner Middle involucral bracts 5-6(-8), green, lanceolate, concave to flat 6.2-7.1 × 1.06-1.25(-1.51) mm, with 3 dark-green longitudinal stripes (including the midrib), apex acute, texture leaf-like to hyaline-membranaceous towards both lateral margins, margin ciliate, cilia (0.11-)0.17-0.21(-0.24) mm long, central portion of the abaxial lamina densely covered by glandular trichomes, hyaline lamina glabrous, adaxial lamina glabrous. Flowers isomorphic, bisexual, 27-30 per capitulum. Corollas bilabiate, white, before anthesis pinkish-white, tube 3.7-4.0 mm long, 0.5-1.1 wide; corolla tube sparsely covered by glandular trichomes. Outer lip oblanceolate, 3.6-3.9 × 2.0-2.2 mm at its widest, apex 3-toothed, teeth equal, 4-veined, glabrous. Inner lip bifid, lacinae linear, 2.7-2.8 × 0.24-0.37 mm at its widest, connivent, glabrous. Stamens 5, 3.8-4.0 mm long, glabrous. Anthers sagittate, 3.25-3.29 mm long; apical appendages purple, lanceolate, 1.19-1.23 mm long, apex acute; tails long, lanceolate, ca. 0.6 mm long, apex acute, smooth to ciliate. Styles white, 4.2-5.0 mm long, cleft into two truncate branches, branches 0.54-0.73 mm long, with stigmatic papillae on internal surface. Cypselae dark-brown, 1.0-1.2 × 2.4-2.5 mm, obovoid, strigose; trichomes transparent, cylindric, terete, (150-)167-170(-180) µm, ascending, unicellular, subtended by two globose exocarpic cells. Pappus uniseriate, fused at their bases into a ring, deciduous; bristles 19-20, white, capillary, sub-plumose, 4.5-5 mm long; pectines long, filiform, 0.21-0.35(-0.46) mm long, laterally inserted.

Distribution and habitat.

Leucheria cantillanensis seems to be endemic to the Cantillana Mountain Range, which is part of the coastal mountain range of central Chile. It grows in shaded crevices of rocky outcrops near 2000 m a.s.l. with SW orientation (Fig. 7 ). It is known thus far only from the type locality (Fig. 1 ). L. cantillanensis occurs associated with other rupicolous taxa such as Calceolaria andina Benth.

Phenology.

Collected flowering and fruiting in December.

Etymology.

The specific epithet refers to the coastal mountain range where the species was found, Altos de Cantillana.

Conservation status.

Leucheria cantillanensis is assessed here as Critically Endangered (CR) under the IUCN categories and criteria B2ab(i,ii,iii). Criterion B2 was selected because its Area of Occupancy is <10 km2 (4 km2). Criterion “a” was selected because it is known to exist at only a single location, with only one subpopulation. Criterion b(i,ii,iii) was selected because we expect a continuing decline of suitable area for the species to exist in since it is only found at the highest elevations within the mountain coastal range with very specific soil types and exposition. The quality of its habitat has also been deteriorating over time. The overall precipitation and snow cover in the Cantillana plateau has decreased dramatically over the past 20 years, affecting not only the Andean relict flora but all the vegetation in the area. Fog events which compensate for the drought over the summer, are not as common as before. Leucheria cantillanensis is present in the private reserve "Reserva Natural Altos de Cantillana".

Figures

Figure 1. Distribution map of Leucheria cantillanensis (star) in Chile, Region Metropolitana, based on the type locality.

Figure 3. Leucheria cantillanensis Lavandero, sp. nov. A capitulum, sideways view B capitulum, detail of Middle involucral bracts C leaves D capitulum, upper view E plants growing in natural habitat F cypsela G detail of trichomes in cypsela. All photographs by Nicolas Lavandero.

Figure 4. Leucheria cantillanensis Lavandero, sp. nov. A habit B capitulum C detail of flower D fruit E basal leaf F leaf trichome G stem trichome H inner Middle involucral bract I middle Middle involucral bract J outer Middle involucral bract K ciliate margin of inner Middle involucral bract (detail). Illustrations by Benito Rosende.

Figure 5. Leaf morphology and habit of acaulescent / subacaulescent Leucheria from Central Chile A Leucheria scrobiculata (NL 433, CONC), inset: Habit B Leucheria candidissima (Lavandero, Santilli & Ossa 36, CONC), inset: Habit C Leucheria salina (Lavandero & Abello 40, CONC), inset: Habit D Leucheria cantillanensis (NL 700, CONC), inset: Habit. All photographs by Lavandero.

Figure 6. Leucheria salina (A, D, G, J) (Valle Nevado, Region Metropolitana, Chile), Lecheria runcinata (B, E, H, K) (Reserva Natural Altos de Cantillana, Region Metropolitana, Chile), and Leucheria cantillanensis (C, F, I, L) (Reserva Natural Altos de Cantillana, Region Metropolitana, Chile) A-C habit D-F capitula G-I abaxial side of leaves J-L belowground structures. All Photographs by Lavandero.

Figure 7. Habitat of Leucheria cantillanensis in Central Chile A southwest facing rock outcrops, ca. 2000 m elevation B rock outcrops in Cantillana, general view C general view of rock outcrops among Nothofagus macrocarpa (A. DC.) F. M. Vazquez & R. A. Rodr. forests in the Cantillana plateau D Leucheria cantillanensis, detail of the plant growing between rock crevices. Photographs A, D by Lavandero, B, C by Fabiola Gamboa.