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Bol. Soc. Bot. Méx. 83: 00-00 (2008) TAXONOMÍA Y FLORÍSTICA

Cornisa izquierda: Carrillo-Reyes y Lomelí-Sención

Cornisa derecha: New Sedum endemic to Jalisco
Sedum chazaroi (Crassulaceae), an endemic new species from southern Jalisco, Mexico
Pablo Carrillo-Reyes1, 3 and José Aquileo Lomelí-Sención2

1Departamento de Biología Evolutiva, Instituto de Ecología, A.C. Apartado Postal 63, 91000 Xalapa, Veracruz, México

2Jardín Botánico y Herbario, Escuela de Biología, Universidad Autónoma de Guadalajara, Apartado Postal 1-440, Guadalajara, Jalisco, México

3 Author for correspondence. E-mail: pcarreyes@gmail.com
Abstract: Sedum chazaroi (Crassulaceae), an endemic new species from southern Jalisco, Mexico, is described and illustrated. This taxon belongs to section Sedastrum (Rose) Berger on account of its basal rosettes, dense pubescence and paniculate inflorescences. It can be separated from the other species of section Sedastrum by their bigger rosettes (1.5-6 cm in diameter), larger and thicker inflorescences (57-85 cm long and 1.1-1.8 cm in diameter) and denser pubescence. Sedum chazaroi is compared with S. mocinianum Pérez-Calix and S. ebracteatum Sessé & Moc. to which it seems to be closed allied.

Keywords: Crassulaceae, Sedastrum, Sedum, Jalisco, Mexico, Mexican endemic species, succulent plants.
Resumen: Se describe e ilustra Sedum chazaroi (Crassulaceae), una especie nueva endémica del sur del estado de Jalisco, México. Este nuevo taxón pertenece a la sección Sedastrum (Rose) Berger por presentar rosetas basales, pubescencia densa e inflorescencias paniculadas. Se distingue de las demás especies de esta sección por sus rosetas de tamaño mayor, las cuales llegan a medir 1.5-6 cm de diámetro, las ramas floríferas de 57-85 cm de largo y 11-18 de diámetro, y por su indumento más denso. Se le compara con Sedum mocinianum Pérez-Calix y con S. ebracteatum Sessé & Moc., con los cuales parece estar estrechamente relacionado.

Palabras clave: Crassulaceae, Sedastrum, Sedum, Jalisco, México, especies mexicanas endémicas

Sedum section Sedastrum (Rose) Berger (Crassulaceae) is characterized by their dense basal rosettes of usually pubescent leaves; fleshy, thickened rootstocks; numerous stems dying back after flowering; paniculate inflorescences; and flowers with white, very thin petals that posses a nectarial concavity (Clausen, 1943; Uhl, 1992). This section contains about five species (Pérez-Calix, 1998) distributed from northern Mexico to Honduras, with the main diversity in central Mexico (Clausen, 1943; Uhl, 1992).

During botanical exploration trips to southern Jalisco, we collected a member of Sedum section Sedastrum with long and pendulous floriferous stems that cannot be identified as any of the known species of the section. After review of the available literature (Clausen 1943, 1978, 1979; Pérez-Calix, 1998) we concluded this species has never been published, and thus propose it here as a new species for science:


Sedum chazaroi P. Carrillo & J. A. Lomelí sp. nov. (Figure 1).

Planta herbacea perennis, dense pubescens, caulibus ramosis ad 10 cm longis, rosulae folia 25-35 (-70) densis disposita vel spiraliter, triangularis vel oblongae, 8-33 mm longis, inflorescencia paniculata ad 85 cm longis, decumbentis vel pendulis, ramis 9-26 late divaricatis ad 15.5 cm longis, 3 ad 27 flores habent, flores sessiles vel subsessiles, petalae 5, alba, 4-5 mm longa, carpella 5, glabra, 4.5-5.5 mm longa, ad basem cavata.



TYPE: México, Jalisco, Municipio de Tolimán, arroyo La Ciénega, 19º36’N, 103º54’W, 760 m. Tropical deciduous forest; rocky cliffs of N and NW exposure; 20 Dec 2005; P. Carrillo-Reyes y J. A. Lomelí-Sención 5105. (Holotype: GUADA; Isotypes: IBUG, IEB, MEXU, MICH, MO, NY, XAL).
Perennial herb densely pubescent throughout (except petals, stamens and carpels), pubescence of hyaline hairs ca. 0.5 mm long. Sterile stems erect, to 10 cm long, 8-10 mm in diameter at the base. Leaves 25-35 (70), rosulate, crowded, spiraled, triangular when young, oblong-elliptic to oblong at maturity, 8-33 mm long, 4-10 mm wide and ca. 4 mm thick, apex acute. Floriferous stems decumbent to pendulous, (30-) 50-85 cm long, 11-18 mm in diameter at the base. Inflorescence a panicle, peduncle to 62 cm long with 9-26 secondary thyrsoid branches 8-15.5 cm long, each branch with 3-27 flowers in cincinnae 6-25 mm long; bracts similar to the leaves, linguiform to oblong, 10-32 mm long, 5-10 mm wide and 5-7 mm thick; bractlets linguiform, 4-8 mm long, 4-7 mm wide and 2-4 mm thick. Flowers sessile to subsessile, 9-10 mm in diameter, with a fetid odor; calyx pubescent, with 5 free subequal lobes, green-whitish in color, the lobes deltate to triangular, 2-3 mm long, 1.5-2.5 mm wide at the base, apex obtuse; corolla glabrous, with 5 free white petals, these ovate to elliptic, ca. 5 mm long, 2-3 mm wide in the widest part; stamens 10, glabrous, 5 of them opposite and adnate to the petals, 2-2.5 mm long, the other 5 alternate to the petals, 4-5 mm long, filaments white, anthers pinkish at the predehiscence; pollen whitish; nectaries oblong to ovate, ca. 0.4-0.5 mm long, carpels glabrous, vesciculose, whitish green, 4.5-5.5 mm long including the style, with a concavity at the base when nectarial scale is placed, styles ca. 1.5 mm long, terete; follicles containing numerous seeds.
Distribution and habitat: Sedum chazaroi is a narrow endemic from southern Jalisco, it is only known from two localities whose populations are small in size. It grows on vertical, rocky cliffs intermittent streams from 750 to 1360 m of altitude. The vegetation at both collection sites is a tropical deciduous forest with Bursera spp., Cnidoscolus sp., Euphorbia macvaughii S. Carvajal Hernández & I. R. Lomelí González, E. oaxacana Robs. & Greenm., Fouquieria formosa H.B.K., Hechtia sp., Mammillaria sp., Pilosocereus sp. and Stenocereus sp.

Phenology: Flowering from November to January.

Additional examined specimens: MEXICO, Jalisco. Mpio. Tolimán, arroyo La Ciénega, Tolimán, 19 Sep 1987, J.A. Lomelí-Sención 87-01056 (IEB); ibíd. 11 May 1991 (probably pressed later), E. Sahagún s.n. (GUADA, OAX); Municipio de Tenamaxtlán, Arroyo San Ignacio, 1 km al SE de San Ignacio, 20°01'20.8'' N , 104°09’10.2'' W. alt. 1360 m, Oct 2005, G. Tinoco & H. Orozco s.n. (GUADA, IBUG).
Discussion: In recent phylogenetic analysis, including Mexican Sedum, (Carrillo-Reyes et al., in prep.) the new species comes out with S. hemsleyanum Rose and S. hintonii R.T. Clausen, the only two additional accessions of Sedum sect. Sedastrum sampled. These results support its placement in this infrageneric group. Additional studies that include all representatives of Sedum sect. Sedastrum are necessary to accurately determinate the affinities of the new species. Based on morphological features, Sedum chazaroi seems to be closely related to S. mocinianum Pérez-Calix. Both species are rock-dwelling plants with succulent leaves densely covered by hyaline hairs ca. 0.5 mm long. However, the former is a more robust plant with rosettes of 25-35 (-70) leaves (vs. 12-18) and paniculate inflorescences to 85 cm long (vs. thyrse inflorescences about 10 cm long). These species are also geographically and ecologically separated, Sedum chazaroi is distributed in southern Jalisco in tropical deciduous forest between 750 and 1360 m altitude, whereas S. mocinianum occurs in Guanajuato and northern Jalisco in tropical deciduous forest and the ecotone with xerophitic scrub, between 1480 and 2400 m of altitude. The new species can also be confused with the widely distributed S. ebracteatum Sessé & Moc., both of which are robust plant with thyrse inflorescences that occur in tropical deciduous forest in wetsern Mexico. However, S. chazaroi can be distinguished by the presence of dense pubescence (vs. moderate pubescence), its oblong-elliptic to oblong leaves (vs. suborbicular to oblong-spathulate) and its very large inflorescences of (30-) 50-85 cm long (vs. 10-40 cm long). In addition, although S. ebracteatum is widely distributed, apparently there are no collections known from southern Jalisco. A comparison of the salient morphological features of S. ebracteatum, S. mocinianum and S. chazaroi is presented in Table 1.
Etymology. The specific epithet honors our friend, Dr. Miguel de Jesús Cházaro-Basáñez from the Departamento de Geografía y Ordenamiento Territorial of the University of Guadalajara, who has been made noteworthy contributions to the knowledge of succulent plants mainly from Western Mexico.
Acknowledgments

We thank Victor W. Steinmann for reviewing the manuscript and give us valuable comments; the biologists Georgina Tinoco-Villa and Hugo Orozco-Jiménez for making available their collections of this new species; and also Manuel Martínez-Rufino who invited to J.A. Lomelí-Sención to know the Tolimán region, Jalisco, for the first time in the 1980s.


Literature cited

Carrillo-Reyes, P., V. Sosa & M. Mort. In prep. Molecular phylogenetics of the “Acre clade” (Crassulaceae); The most diverse group in stonecrops.

Clausen, R.T. 1943. The section Sedastrum of Sedum. Bulletin of The Torrey Botanical Club 70: 289-296.

Clausen, R.T. 1978. Sedum-seven Mexican perennial species. Bulletin of The Torrey Botanical Club 105: 214-223.

Clausen, R.T. 1979. Sedum in six areas of the Mexican Cordilleran Plateau. Bulletin of The Torrey Botanical Club 106: 205-216.

Pérez-Calix, E. 1998. Sedum mocinianum (Crassulaceae) una especie nueva del centro de México. Acta Botánica Mexicana 45: 49-54.

Uhl, C. 1992. Chromosomes of Mexican Sedum VI. Section Sedastrum. Rhodora 94: 362-370.

Table 1. Comparison of salient morphological features between Sedum chazaroi and its putative closest relatives.



Species (Source)
Feature

S. chazaroi

S. ebracteatum (Clausen, 1943; Pérez-Calix, 1998)

S. mocinianum (Pérez-Cálix, 1998)

Indumentum

dense

moderate

dense

Number of leaves per mature rosette

25-35 (-70)

15-25

12-18

Leaf shape

triangular, oblong-elliptic to oblong

Suborbicular to oblong-spatulate

elliptic to oblong-elliptic

Floriferous stem position

Decumbent or pendulous

Erect, decumbent or pendulous

Erect

Floriferous stem length (cm)

57-85

15-25

3-10

Number and length of panicle branches

9-26, to 15 cm

1-18, to 15 cm

to 10, less than 5 cm

Number of flowers per branch

3-27

(3-) 6-more than 60

1-3

Bract length (mm)

10-32

20-80

4-9

Bract width (mm)

5-10

10-25

3-7


Fig. 1. Sedum chazaroi P. Carrillo & J.A. Lomelí. A. Habit, depicting the rosettes and pendulous floriferous stem; B. José A. Lomelí showing a mature plant with pendulous inflorescence; C. Inflorescence; D. Detail of inflorescence; E. Habitat in rocky ravines at Arroyo La Ciénega, Tolimán, Jalisco (All pictures from type collection).


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