Cosmos pseudoperfoliatus Art. Castro, M. Harker & Aaron Rodr., 2013

Castro-Castro, Arturo, Harker, Mollie, Vargas-Amado, Georgina & Rodríguez, Aarón, 2013, Two new species of Cosmos section Discopoda (Coreopsideae: Asteraceae) from Jalisco, Mexico, Phytotaxa 146 (2), pp. 35-49 : 38-40

Cosmos pseudoperfoliatus Art. Castro, M. Harker & Aaron Rodr. sp. nov. ( Figures 1 , 2B, E, G, H )

Species nova Cosmo jaliscensi et C. scabiosoide affinis sed foliorum paribus 4–7 per caulem, foliis sessilibus utrinque dense pubescentibus, pedunculis elongatis 13–25(–30) cm longis, involucri phyllis exterioribus 7–8 praecipue trulliformibus vel ovatis obscure 3-striatis, floribus ligulatis violaceis, floribus tubulosis 51–80 omnino flavis 4–5- lobatis, acheniis 2-aristatis tuberculatis glabris differt.

Type:— MEXICO. Jalisco: Guachinango, Puerto Santa Cruz del Roble , 3.5 km al oeste de Guachinango, carretera Ameca-Mascota, 1580 m, 20º 30’13.5”N, 104º 21’16.8” W, 28 July 2011 (fl, fr), M . Harker , A . Castro-Castro , J . G . González-Gallegos & E . A . Suárez-Muro 4189 (holotype IBUG!; isotypes, IEB!, MEXU!, XAL!) .

Perennial herbs, 60–80 cm, with rhizome and rootstock, tubers 3.0–10.0 cm long. Stems erect or rarely decumbent, simple, 30–50 cm, terete, sulcate, tomentose, hairs multicellular. Leaves 4–7 per stem, opposite, almost perfoliate, membranaceous, ovate to deltate in outline, 4.5–7.5 cm long, 3.5–4.5 cm wide, simple, irregularly lobed or occasionally pinnatifid, when lobed the two lateral lobes lanceolate, tomentose, 3.5–4.5 cm long, 0.5–1.0 cm wide, the central lobe elliptic, 4.5–7.5 cm long, 2.0– 2.5 cm wide, entire or with one short lateral acuminate lobe, leaf base and apex variable, margin slightly revolute, antrorse and scabrous, lamina pubescent on both faces with multicelular hairs, lighter green below. Synflorescence corymbiform, 1–3 terminal heads, peduncles 13.0–25.0(–30.0) cm, slender, glabrescent. Heads radiate, heterogamous, hemispheric, 3.7–6.5 cm wide across the extended rays. Involucre 1.4–1.7 cm wide, 0.8–1.0 cm high, cupshaped. Phyllaries biseriate; outer series 7–8, green, 6.0– 7.5 mm long, 2.0–4.0 mm wide, trulliform to obovate, adpressed to sigmoid, glabrous, shiny, with 3 inconspicuous resiniferous ducts on the abaxial face, apices acute; inner series 8, scarious, translucent, pale yellow to light pink, faintly striped, 6.5–9.0 mm long, 2.6–3.7 mm wide, oblong-ovate, apices acute with a tuft of purple multicelular hairs. Receptacle convex, paleaceous, 4.0–5.0 mm in diameter. Paleae translucent yellow, 9.0–10.0 mm long, 8.0–9.0 mm wide, persistent and resembling the inner phyllaries. Ray florets 8, uniseriate, sterile, violet, limb obovate, apices obtuse, trilobulate, 1.8–3.0 cm long, 1.3–1.5 cm wide, 3–5 ribbed outside, ribs glabrescent above, pubescence increasing in density towards the base, with simple and multicellular hairs. Disk florets 50–80, hermaphrodite, 6.0– 7.5 mm long, yellow; tube 2.0– 2.8 mm long, 0.5 mm wide, glabrescent and pubescence increasing in density towards the base, hairs simple; throat 4.2–5.0 mm long, 1.0– 1.2 mm diameter, glabrous; lobes 4–5, 0.7 mm long, erect, triangular, acute, margins sparsely papillate and slightly revolute, 0.8–1.0 mm diameter of extended lobes. Anthers 4–5, cylinder brown, 2.5–3.0 mm long, apical appendages ovate; pollen yellow. Style 3.0–5.0 mm long; stigma lobes yellow, 3.0 mm long, apices acute, penicillate, papillate beneath and along margins. Achenes 1.0– 1.6 cm long, 1.6–1.8 mm wide, light brown, fusiform, tetrangular, with deep furrows between angles, glabrous, tuberculate, attenuate, carpopodium annular, pappus awns 2, 2.0– 2.2 mm long, each with 8–10 retrorse barbs.

Distribution, habitat and phenology:— Cosmos pseudoperfoliatus has been collected in the Atenguillo River basin, in western Jalisco. As far as we know, it is endemic to a limestone mountain system in that region. It grows in open oak, juniper and pine woods, with grasses and few other herbaceous perennials. It is associated with Pinus oocarpa , Juniperus flaccida , Quercus resinosa , Acacia pennatula , Bejaria mexicana , Prochnyanthes mexicana , Salvia angustiarum , S. heterotricha , S. pugana , Ageratina spp. , and Verbesina spp. The plants are found in areas with thin and eroded calcareous soils at the elevation of 1580–1650 m, flowering from late July to mid August and fruiting in August and September.

Etymology:— The epithet of the species refers to the almost perfoliate leaves, a unique character of the species.

Taxonomic relationships:— Cosmos pseudoperfoliatus is a perennial herb growing from a short rhizome with tuberous roots and therefore, it pertains to Cosmos section Discopoda . It is characterized by a combination of characters which include: frequently decumbent habit, tomentose stems, sessile and almost perfoliate leaves, tomentose on both faces, entire to deeply lobed, with 4–7 pairs of leaves below the synflorescence, peduncle 13.0–25.0(–30.0) cm long, external phyllaries 7–8(–10) trulliform to obovate, with 3 inconspicuous resiniferous ducts on the abaxial face, heads 3.7–6.5 cm wide across the extended rays, ray florets violet, disk florets 50–80, completely yellow, 4–5-lobed, achenes tuberculate and glabrous, and pappus awns 2 ( Figures 1 and 2 ). Morphologically, C. pseudoperfoliatus shares similarities with C. jaliscensis Sherff (1964: 66–68) , C. palmeri Robinson (1909: 623) , C. peucedanifolius Weddell (1856: 70) and C. scabiosoides Kunth (1820: 242–243) . Table 2 shows a morphological comparison of these species.

Cosmos jaliscensis , C. scabiosoides and C. pseudoperfoliatus have been collected in the same area, although we have never found sympatric populations. Cosmos jaliscensis is found at the elevation of 1800– 2000 m in pine-oak forest with acidic soils. Likewise, C. scabiosoides has an ample elevation range from 1400 m to 3300 m in oak, oak-pine or pine forest with acidic soils, while C. pseudoperfoliatus is only known from about 1600 m elevation in oak-juniper-pine forest with basic calcareous soils. Lastly, C. palmeri grows at elevations between 1800–2750 m in pine-oak forest with acidic soils.

Conservation assessment: —One population with about forty individuals has been found. Based on this knowledge, Cosmos pseudoperfoliatus should be classified as critically endangered (CR, criterion D), according to the International Union for the Conservation of Nature ( IUCN 2008).

Additional material examined (paratypes):— MEXICO. Jalisco: Guachinango, km 41.5 carretera Ameca-Mascota, 3.5 km al oeste de Guachinango, paraje Santa Cruz del Roble , 1597 m, 20º30’2.1”N, 104º21’15.8”W, 20 October 2009 (fr), A . Castro-Castro & A. Rodríguez 1979 ( IBUG!, MEXU!); km 41 carretera Ameca-Mascota, 1597 m, 20º30’2.1”N, 104º21’15.8”W, 4 September 2009 (fr), A . Rodríguez, M. Guerritsen & R. Parsons 5908 (IBUG!, MEXU!).

Figures

FIGURE 1. Cosmos pseudoperfoliatus Art. Castro, M. Harker et Aaron Rodr. A. Habit with a detail of stem pubescence. B. Rhizome and tuberous roots. C. Leaf shape variation. D. Head, front view. E. Head, lateral view with phyllaries. F. Ray floret with tube details. G. Disk florets and palea. H. Style and stigma details. I. Anthers and pubescent filaments. J. Tuberculate achenes, dorsal and lateral view. Illustrated by Oswaldo Zuno Delgadillo based on M. Harker et al. 4189 (IBUG holotype).

FIGURE 2. Cosmos ramirezianus Art. Castro, M. Harker et Aaron Rodr. A. Head, front view. C. Leaves. D. Phyllaries. F. Achenes and persistent paleae. A and D based on A. Frías & L. M. González-Villarreal 1864 (IBUG); C and F based on A. Castro-Castro & L. M. González-Villarreal 2295 (IBUG). Cosmos pseudoperfoliatus Art. Castro, M. Harker et Aaron Rodr. B. Head, front view. E. Head, lateral view. G. Leaves. H. Head, dorsal view [based on M. Harker et al. 4189 (IBUG holotype)].