Cosmos ramirezianus 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 : 40-44

Cosmos ramirezianus Art. Castro, M. Harker & Aaron Rodr. sp. nov. ( Figures 2A, C, D, F and 3 )

Herba perennis rhizomatosa et radicibus tuberiferis Cosmo montano affinis, a quo foliis coriaceis semper pinnatisectis, synflorescentiis capitulis 3–10, floribus ligulatis et tubulosis, subpurpureis, nec non paleis persistentibus distincta est.

Type: — MEXICO. Jalisco: Zapopan, Cerro Los Bailadores , 1780 m, 20º 47’ N, 103º 37’ W, 28 August 2012 (fl), A . Castro- Castro , J . G . González-Gallegos & E . A . Suárez-Muro 2916 (holotype IBUG!; isotypes, IEB!, MEXU!, XAL!) .

Perennial herbs, 90–120 cm, with rhizome and rootstock, tubers 5–8 cm long. Stems erect, simple, 70–80(– 90) cm, sulcate, terete to hexangular, pubescent, hairs multicellular. Leaves opposite, coriaceous, deltate in outline, 10.0–18.0(–20.0) cm long, 12.0–16.0(–18.0) cm wide, pinnatisect, lamina glabrous and dull steelgreen above, paler beneath, midrib grooved above and prominent beneath. Petioles 2.0–3.0 cm long, amplexicaule at base, winged, wings flat, 1.0– 1.5 mm wide. Leaf segments (3–)5(–7), opposite, 4.0–10.0(– 14.0) cm long, 2.0–5.0 mm wide, linear, single-veined, lower surface glabrescent, apices acute; margin entire, slightly revolute, with short rigid and antrorse hairs. Synflorescence corymbiform, 3–7 heads, peduncles (3.0–)15.0–25.0(–35.0) cm, slender, elongate and glabrescent. Heads radiate, heterogamous, 3.5 cm wide across the extended rays. Involucre 0.8–1.3 cm wide, 1.0– 1.3 cm high, cup-shaped. Phyllaries biseriate; outer series (6–)8(–10), green, 4.0–7.0(–9.0) mm long, 1.0–2.0 mm wide, lanceolate, adpressed to sigmoid, glabrous, shiny, with 4–5 light brown resiniferous ducts, acute; inner series 8–11, scarious, yellow below and purple above, faintly 2–3 green-striped, 6.5–12.0 mm long, 2.5–4.0 mm wide, oblong–ovate, apices acute with a tuft of multicelular hairs. Receptacle convex, paleaceous, 5.0–6.0 mm in diameter. Paleae translucent, 7.0–9.0(–12.0) mm long, 1.0– 2.5 mm wide, persistent and resembling the inner phyllaries. Ray florets 8, uniseriate, sterile, light purple, limb obovate, apices obtuse, entire or trilobulate, 1.5–2.0 cm long, 8.0–15.0 mm wide, 3–7 ribbed outside, ribs glabrescent above, pubescence increasing in density towards the base, with uniseriate and multicellular hairs. Disk florets 45–50, hermaphrodite, 4.5–4.8 mm long; corolla tube yellow, 2.2–2.4 mm long, 0.5 mm wide, glabrescent and pubescence increasing in density towards the base; throat 2.0 mm long, 1.5 mm diameter, glabrous; lobes 5, 0.7 mm long, purple, erect, deltate, acute, margins sparsely papillate and slightly involute, 1.5 mm wide across the extended lobes. Anthers 5, cylinder light brown, 2.5 mm long, apical appendages deltate; pollen yellow. Style 6.5–8.5 mm long; stigma lobes yellow, 1.5 mm long, acute, penicillate, long papillate beneath and along the margins. Achenes 9.0–12.0 mm long, 1.2–1.3 mm wide, dark brown, fusiform, tetrangular, deeply furrowed, glabrous to scabrous on the rounded angles, attenuate, carpopodium annular, pappus awns 2, 2.0– 2.2 mm long, each with 8–16 retrorse, decussate barbs.

Distribution, habitat and phenology:— Cosmos ramirezianus is known from central Jalisco, in the vicinity of La Primavera Nature Reserve, west of Guadalajara. The region drains to the upper basin of the Ameca River on the south and to the Santiago River basin on the north. The Guadalajara metropolitan area limits the region on the east and the Valley of Tala on the west. It grows on deep, acidic soils in open pine and oak woods, in association with Pinus oocarpa , Quercus praineana , Q. resinosa , Acacia pennatula , Calliandra hirsuta , Manfreda scabra , Iostephane heterophylla , Salvia angustiarum , S. heterotricha , Schizachyrium sanguineum , and Tigridia dugesii . It flowers from late June to September and fruits in October and November.

Etymology:— The specific epithet honors Raymundo Ramírez Delgadillo (1963–2011), an outstanding botanist and expert on the flora of western Mexico. His collections contributed significantly to the development of the herbarium Luz María Villarreal de Puga of the Instituto de Botánica, Universidad de Guadalajara (IBUG). Also, he was responsible for the formation of a new generation of young botanists.

Taxonomic relationships: — Cosmos ramirezianus is a perennial herb that grows from a short rhizome with tuberous roots, and therefore it pertains to Cosmos section Discopoda . It shares leaf features with Cosmos crithmifolius Kunth (1820: 242) . In fact, all specimens were erroneously identified as such in all herbaria vouchers consulted. However, C. crithmifolius is a suffrutex plant with a rhizome and a woody axonomorphic root (xylopodium) and belongs to Cosmos section Mesinenia .

Morphologically, Cosmos ramirezianus shares similarities with C. montanus Sherff (1932: 433) . It has coriaceous and pinnatisect leaves, as opposed to the membranaceous and simple, pinnatisect or bipinnatisect leaves of C. montanus . They also differ in the colour of the ray florets and the paleae. Cosmos ramirezianus has reddish to light purple ray florets and persistent paleae, while C. montanus has dark to light purple ray florets and deciduous paleae. In addition, the corolla lobes of the disk florets in C. montanus are yellow, as opposed to light purple in C. ramirezianus ( Figures 1–2 ). Additional differences can be found in general habit, pubescence, leaf size, involucral parts and floral characters as shown in Table 3. Finally, C. ramirezianus has a chromosome number of n = 12 in contrast to n = 12 or 24 in C. montanus (unpublished data).

Conservation assessment: — Cosmos ramirezianus appears to be in danger of extinction, based on its rarity and limited geographic range. It should be classified as critically endangered [CR, criteria C2a(i)] according to the IUCN (2008). Changes in land use are the greatest threat to this species. New housing developments are being built in the vicinity, so efforts to discover additional populations are needed.

Additional material examined (paratypes): — MEXICO. Jalisco: Zapopan, Villa Primavera, La Herradura, 1550 m, 20º43’N, 103º33’W, 10 July 1988 (fl), L . M . Villarreal de Puga 13414 ( IEB!); Fraccionamiento La Herradura, anexo al Club de la Universidad de Guadalajara , Villa Primavera , 1560 m, 9 September 1996 (fl), L . M . Villarreal de Puga 17207 ( IBUG!); Villa Primavera , 1540 m, 10 July 1988 (fl), L . M . Villarreal de Puga 13451 ( HUMO!, IBUG!); Villa Primavera, Fraccionamiento La Herradura , 30 km al NO de Guadalajara, 1550 m, 25 June 1986 (fr), L . M . Villarreal de Puga 13448 ( IBUG!); Calle Encino del Fraccionamiento La Herradura , 25 km al oeste de Guadalajara, 1570 m, 21 October 2010 (fl), A . Frías-Castro & L . M . González-Villarreal 1864 ( IBUG!); Fraccionamiento La Herradura al oeste de Guadalajara , 20º46’N, 103º36’W, 1570 m, 20 July 2011 (fr), A . Castro-Castro & L . M . González-Villarreal 2295 ( IBUG!); Cerro Los Bailadores, camino ascenso a partir del Fraccionamiento La Herradura , 1780 m, 20º47’N, 103º37’W, 26 August 2012 (fl), M . Leyva & A . Frías-Castro 86 ( 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)].

FIGURE 3. Cosmos ramirezianus Art. Castro, M. Harker et Aaron Rodr. A. Habit. B. Rhizome and tuberous roots. C. Leaf and margin details. D. Synflorescence. E. Head, front view. F. Head, lateral view. G. Ray floret and tube details. H. Disk florets, anthers, style and stigma details. I. Heads in fruit with persistent paleae. J. Achenes, lateral and dorsal views. A–C, I and J from A. Castro- Castro et al. 2916 (IBUG); D–H from A. Frías & L. M. González-Villarreal 1864 (IBUG). Illustrated by Oswaldo Zuno Delgadillo.