Senecio sykorae Montesinos, 2014

Tubee, Daniel B. Montesinos, 2014, Three new caespitose species of Senecio (Asteraceae, Senecioneae) from South Peru, PhytoKeys 39, pp. 1-17 : 4-5

Senecio sykorae Montesinos sp. nov. Figs 2 , 4B , 5

Diagnosis.

Morphologically similar to Senecio gamolepis but clearly distinguished by the tuft mat habit (vs. cushion mats), the leaf shape being obovate-spathulate (vs. linear-lanceolate), corolla white (vs. yellow), phyllaries 12-14 (vs. 7-9), disc length 7-9 mm (vs. 8-12 mm), and achene length 1.5-2 mm (vs. 1-1.3 mm).

Type.

PERU: Moquegua Region, General Sánchez Cerro Province, Yunga District, E of Yunga, terrestrial on bare clayey soils on the peaks of Perusa mountain, elevation 4802 m, 16°11'08"S, 70°38'14"W, 13 April 2012, Montesinos & Calisaya 3805 (holotype USM!, isotype HUSA!).

Description.

Perennial herb, decumbent, low-growing and forming small tuft mats 4-6 cm high and up to 6 cm in diam. Trichomes absent. Stems 3-5 cm long, densely leafy, woody and branched at the base. Leaves cauline, alternate, lamina obovate-spathulate, 9-14 mm long × 1-2.2 mm wide, glabrous on surface and margins except at the base (scarcely covered by thin, short trichomes), base truncate to auriculate, apex obtuse, entire, margin involute; young leaves pale green with yellowish margins turning dark green with age. Synflorescences of solitary, terminal capitula. Capitula homogamous, discoid and pedicled (5-10 mm long). Involucres at first narrowly cylindrical becoming cylindrical-campanulate with age (7-9 mm long × 3-5 mm wide). Calycular bracts linear-oblong (6-8 mm × 0.7-1 mm), dark green on the surface and light green along the margins, with dark brown-black apex covered with inconspicuous trichomes or glabrous. Phyllaries 12-14, connate, 5-6.5 mm long × 0.6-1 mm wide, linear-lanceolate, margins glabrous, apex dark brown with short trichomes. Florets 13-16; corolla tubular, abruptly constricted near the base, 5-lobed, each lobe 0.2-0.3 mm long, white, tube 2.5-4 mm long × 0.5-0.8 mm wide; anthers linear-lanceolate, 1.5-2 mm long × 0.2-0.3 mm wide, truncate, terminal appendages lanceolate, obtuse; margin whitish transparent and becoming darker towards the centre; style dark purple, truncate, apically covered by papillae equally distributed. Achenes cylindrical, pale green, finely covered with trichomes, 1.5-2 mm long × 0.6-0.9 mm wide; carpopodium symmetrical in a shallow ring; pappus of smooth fine bristles, white, 4-6 mm long, with fine alternate single setulae.

Ecology and distribution.

Terrestrial plant on bare clayey soils on the summits of mountain peaks and grassland plateaus in the north of the Moquegua Region at elevations of 4550-4800 m. Co-occurring with Belloa pickeringii (A. Gray) Sagást. & M.O. Dillon, Nototriche obcuneata (Baker f.) A.W. Hill, Pycnophyllum molle Remy, Senecio candollei Wedd. and Xenophyllum ciliolatum (A. Gray) V.A. Funk. Flowers and fruits between March and April.

Etymology.

This Senecio is named after Karlè Sýkora, a well-known Dutch vegetation scientist who was my mentor in phytosociology.

Additional material examined

(paratypes). PERU. Moquegua Region, General Sánchez Cerro Province, Ubinas District, S of Pillone, terrestrial on bare clayey soils in the verges of the road to Pillone town, elevation 4584 m, 16°10'02"S, 70°49'56"W, 24 March 2013, Montesinos 4023 (USM).

Discussion.

Senecio sykorae appears to be closely related to Senecio gamolepis which grows at higher elevations but approaches the known range of Senecio sykorae within a few hundred metres. While Senecio gamolepis is generally distinctive in the genus for its large size, attaining widths of up to 1 meter in diameter, and for its larger, capitulate form, Senecio sykorae is a smaller plant, of about 4-6 cm wide and has shorter corolla, less than 9 mm long. Senecio sykorae is also distinctive in that it has 12-14 phyllaries per capitulum instead of 7-9 phyllaries in Senecio gamolepis . Likely the leaves of Senecio sykorae are distinctive in that they are obovate-spathulate vs. linear-lanceolate. Also, the achenes in Senecio sykorae are larger (1.5-2 mm long) vs. 1-1.3 mm long in Senecio gamolepis . Senecio sykorae also differs from Senecio algens by the leaf and capitula length (shorter in Senecio sykorae ), and from both species by the corolla colour (white vs. yellow). Less similarity is found in Senecio algens , Senecio humillimus , Senecio trifurcifolius , Senecio pucapampaensis and Senecio evacoides , and from which Senecio sykorae can be distinguished on the basis of its habit, trichomes, leaf shape and length, calycular bracts and phyllary length and shape as summarized in Table 1 .

Conservation status.

Following the criteria and categories of IUCN (2001), a preliminary status of Critically Endangered (CR) is assigned. The new species deserves protection because its total area of occupancy is less than 10 km² (ca. 5 km²) (B2); only one population known (B2b); habitat inferred to be continuing to decline (B2b(i-iii)); population estimated to number fewer than 150 individuals (D). The suitable habitats for Senecio sykorae on the mountain summits of the north of Moquegua are indicated as endangered because of overgrazing of grasslands, changes in annual rainfall, volcanic activity, and exploitation of natural resources, all potentially reducing their extent.

Figures

Figure 2. Senecio sykorae Montesinos. A Leaf (upper side) B Leaf (underside) C Capitulum D Calycular bracts E Phyllary F Stamens arrangement in a floret G Floret H Pappus bristles I Stamens J Style K Papillose stigma L Achene

Figure 4. Habit photographs of: A Senecio moqueguensis B Senecio sykorae C Senecio tassaensis.

Figure 5. Distribution map showing collection and recorded sites for Senecio moqueguensis (red circles), Senecio sykorae (yellow squares) and Senecio tassaensis (green triangles). Inset: Photograph of the highland plains of Tassa, Moquegua, where populations of Senecio moqueguensis occur.