A new species of Cuscuta (Convolvulaceae) from Michoacán, Mexico

A new species of Cuscuta (Convolvulaceae) from Michoacán, Mexico MIHAI COSTEA1, IGNACIO GARCÍA RUIZ2,

AND

MARK WELSH1

1

Department of Biology, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5, Canada; e-mail: [email protected]; e-mail: [email protected] 2 CIIDIR-IPN Michoacán, Justo Sierra 28 /Apdo. postal 109, Jiquilpan, Michoacán, C.P. 59510, Mexico; e-mail: [email protected]

Abstract. A new species, Cuscuta cotijana, is described and illustrated from the Trans-Mexican Volcanic Belt in northwestern Michoacán, Mexico. The species is most closely related to Cuscuta jalapensis, C. mitriformis, C. rugosiceps and C. lindsayi, from which it differs by the large spur-like projections on the outer calyx lobes and the ovoid to conical capsule with a small intrastylar aperture. Key Words: Michoacán, Mexico, Convolvulaceae, Cuscuta, Cuscuta cotijana, morphology.

Cuscuta (dodder) comprises about 180 species of holoparasitic herbs with leaves reduced to minute scales; their stems are yellow to orange, filiform, trailing or dextrorsely twining, and attached to the host by numerous small haustoria (Costea & Tardif, 2006). Over 80% of the species belong to the subgenus Grammica, which is the most complex infrageneric taxon of Cuscuta, characterized by separate styles and globose stigmas (Yuncker, 1932; Stefanović et al., 2007). More than one third of the dodder species (69) were described between 1921 and 1961 by Truman George Yuncker (Meurer-Grimes, 1989). The boundaries of some of these species have been questioned in recent years (e.g., Beliz, 1986; Gandhi et al., 1987; Beliz, 1993). Our research within several clades of subgenus Grammica has shown that in most cases, Yuncker’s species correspond to monophyletic entities that are recognizable by their morphological and molecular make-up (Costea et al., 2005, 2006a, b, c; Stefanović et al., 2007). Our preliminary results towards a monograph of the genus indicate that there are at least 15 to 20 new species that need to be described from North and South America to better reflect the diversity within this genus. Cuscuta is largely undercollected in México, Central America, and South America. One new

species from northern Michoacán, México, is proposed in this paper, and efforts are underway to find collaborators and resources necessary to reach other geographical areas that might also harbor new species. The morphology of seeds and pollen was shown to be important for the taxonomy of Cuscuta (Costea et al., 2005, 2006a, b, c). Pictures were taken with the scanning electron microscopes Hitachi S-570 and LEO 1530 FESEM at 15 KV. Samples were coated with 30 nm gold using an Emitech K 550 sputter coater. Terminology regarding the micromorphology of flowers, seeds, capsules, and pollen was described in Costea et al. (2006a). Cuscuta cotijana Costea & I. García, sp. nov. Type: Mexico. Michoacán: Mun. Cotija, Los Gallineros, ca. 1900 m, 19 Apr 1991, I. García Ruiz & A. Olmos 3289 (holotype: CIMI; isotypes: IEB, IBUG, NY, UCR, WLU). (Figs. 1, 2) Cuscutae mitriformi, C. rugosicipiti, C. jalapensi et C. lindsi maxime similis, sed distincta projecturis amplis calcariformibus in lobis externis calycis et capsulis ovoideis vel conicis aperturis intrastylaribus parvis; ab C. mitriformi et C. rugosicipiti differt calyce quam tubo corollae breviore; ab C. jalapensi et C. lindsi differt floribus majoribus atque lobis corollae ac calycis auriculatis.

Brittonia, 60(3), 2008, pp. 235–239 © 2008, by The New York Botanical Garden Press, Bronx, NY 10458-5126 U.S.A.

ISSUED: 30 September 2008

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FIG. 1. Cuscuta cotijana. A. Flower. B. Calyx, opened and flattened, dorsal view. C. Detail of calyx lobe. D. Corolla opened to expose infrastaminal scales. E. Capsule. (From the holotype.)

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FIG. 2. Cuscuta cotijana. Scanning electron photomicrographs of pollen (A, B) and seeds (C, D). (From the holotype.)

Stems 0.6–1.5 mm diam, orange. Inflorescences glomerule-like cymes with 3–15 flowers, often confluent in larger, dense inflorescences; pedicels 1–2.5 mm long; bract 1 at the base of clusters, usually absent at the base of pedicels, 1–2.5×0.8–1.1 mm, fleshy, ovate-triangular to lanceolate, the margins entire, apices acute. Flowers 5-merous, 5–7 mm long, fleshy, white when fresh, creamy to brown when dried; papillae absent; laticifers numerous, isolated or in groups of 2–5, evident in the calyx, corolla and ovary/capsule, mostly ovoid or elongate; calyx creamy-yellow when fresh and brown when dried, campanulate, ca. 1/2–1/3 the length of the corolla tube, divided ca. 2/3 of its length, the tube 1.2–1.35 mm long, the lobes overlapping, 1.2–1.6×2.2–2.8 mm, broadly-triangu-

lar (broader than long), auriculate, margins entire to slightly crenulate, the apices rounded; outer two calyx lobes with a spur- or crest-like projection that extends along calyx lobe for 0.7–1.5 mm and protrudes dorsally for 0.7– 1.2 mm, the projections often denticulate or provided with 2–4 thick fimbriae; corollas persistent on fruit, the tubes campanulate, 3– 3.3 mm long, the lobes initially erect, later spreading or reflexed, 2.2–2.5 mm long, ovate, auriculate, the margins entire, overlapping at base, the apices rounded, initially hooded, later flat; stamens exserted, shorter than corolla lobes, the anthers elliptic to broadly-elliptic, 0.9–1.1×0.6–0.7 mm, filaments 0.7–1 mm long; pollen grains 22–25 μm long, prolate to prolate-spheroidal, the tectum microreticulate;

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lumina maximum diameter 1 μm; supratectal process granular to conical, ± uniformly distributed; infrastaminal scales equaling corolla tube, 2.5–2.7 mm long, oblong to obovate, rounded, ± uniformly, dense fimbriate, fimbriae 0.3–0.9 mm long; styles subulate, basally thickened, apically narrowed, 1.3–2.5 mm long, as long or shorter as the ovary; stigmas 0.4– 0.6 mm in diameter, globose, convoluted. Capsules dehiscent, ovoid to conical, 2–4× 2.5–4 mm, the base of the styles forming a conic beak, 0.9–1.5 mm long, the interstylar aperture barely visible, the corolla persistent around the capsule. Seeds 4 per capsule, broadly elliptic, angled, 1.5–2.1×1.4–1.6 mm, the seed coat wrinkled in a radial pattern, not alveolate when dry, the cells slightly papillate, 18–35 μm in diameter, the epicuticular wax absent, the hilum region round, 0.5–0.7 mm diam., the vascular scar 0.18–0.25 mm long, slightly oblique. Distribution and ecology.—The species was found in Michoacán, Mexico, in the Sierra de Cotija at 1700–1900 m elevation, in ruderal vegetation within villages and in the adjacent, mostly disturbed oak and pine forests, sometimes in the canopy of trees 3– 4 m high above the ground. Hosts: herbaceous and woody plants from genera such as Alnus, Baccharis, Eupatorium, Fuchsia, Salvia, Solanum, Vernonia, and Vitis. Residents of Cotija and Los Amoles report that the species also attacks crop plants such as corn and avocado, for which reason they have tried to eradicate it by cutting it with sickles or machetes. These activities may contribute to the vegetative spreading of the plant. Phenology.—Flowering from December to March; mature capsules from April to May. Etymology.—The specific epithet refers to Sierra de Cotija where the species seems to be localized. Local common name.—Tiripio, probably coming from the Purhépecha language. Additional specimens examined. MEXICO. MICHOACÁN: Mun. Cotija, Sierra de de Cotija, Carretera Cotija-Gallineros, 1.1 km al NE de Los Amoles, 1750 m, 13 Jan 2006, I. García Ruiz 7412 (CIMI, NY, WLU); Los Amoles, 19°42′58.7″N, 102°41′54.1″W, 1800 m, 16 Feb 2007, I. García Ruiz, M. Costea & E. Carranza 7557 (CIMI, F, NY, WLU); Los Gallineros, 19°40′49.7″N,

102°41′28.8″W, 1918 m, 16 Feb 2007, I. García Ruiz, M. Costea & E. Carranza 7560 (CIMI, NY, US, WLU); 16 Feb 2007, E. Carranza, I. García Ruiz & M. Costea 7316 (IEB).

Cuscuta cotijana is a member of the subsect. Subulatae Engelm. ex Yunck., which is characterized by subulate styles that are basally thickened and apically narrowed (Yuncker, 1932, 1965). The phylogenetic affinities of C. cotijana are with the more widespread C. mitriformis, C. rugosiceps, and C. jalapensis, and the rare C. lindsayi, from which it can be easily separated by the large spur-like projections on the outer calyx lobes and the ovoid to conical capsule with a small intrastylar aperture. From C. mitriformis and C. rugosiceps it differs by the calyx that is shorter than the corolla tube; from C. jalapensis and C. lindsayi by the auriculate, and evidently overlapping corolla and calyx lobes. These species have recently been shown to form a subclade in a major lineage of the subgenus Grammica that includes other Mexican and Central American species, as well as two dodders from western Australia and Tasmania (“clade G”, Stefanović et al., 2007). Because there are a few other new related species that must be described from Mexico, an identification key, comparative descriptions, and the phylogeny of species will be provided with the revision of the entire group.

Acknowledgments The authors thank two anonymous reviewers for helpful suggestions that improved the manuscript. The first author gratefully acknowledges that financial support for this research was received from a grant funded by WLU Operating funds, and the second author thanks COFAA and EDI of IPN for the scholarships provided. Guy Nesom kindly translated the Latin diagnosis.

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