Pachyphytum rogeliocardenasii E. Pérez-Calix & R.Torres, 2018

Pérez-Calix, Emmanuel & Torres-Colín, Rafael, 2018, Pachyphytum rogeliocardenasii (Crassulaceae), a new species from northwestern Querétaro, Mexico, Phytotaxa 348 (1), pp. 56-62 : 57-60

Pachyphytum rogeliocardenasii E. Pérez-Calix & R.Torres , sp. nov., Fig. 1 ; Fig. 2 A ‒ D .

Type:— MEXICO. Querétaro: municipio Arroyo Seco, cerca de 2.9 km al sur de Santa María de Cocos, 800 m elevation, 21°18’24.64” N, 99°38’26.54” O, 3 November 2015, E. Pérez 6616 (holotype IEB!, isotypes MEXU!, QMEX!).

Pachyphytum rogeliocardenasii is morphologically similar to P. garciae , which differs in that its leaves are up to 1.3 cm longer and 0.5 cm wider; the bracts of the peduncle are 6‒7.5 mm longer and 2‒3.5 wider; calyx lobes are also larger and corolla lobes are white with an abaxial red spot in the middle.

Suffrutex herb, succulent, pendant, decumbent, glaucous, glabrous; stems often unbranched or branched from near the base, 60 cm long or less, up to 0.6 cm thick. Leaves sessile, arranged in a spiral at the apex of the stem, in lax rosettes, laminas narrowly to widely elliptic or obovate, (2.5 ‒) 3.2 ‒ 5.8 cm long, (1.5 ‒) 1.8 ‒ 2.8 cm wide, (0.4 ‒) 0.6 ‒ 10 mm thick, transversely elliptic in cross-section, apex rounded or obtuse, margin entire, succulent, green, slightly pruinose, glabrous. Inflorescence axillary, near the apex of the branches; peduncle 9 ‒ 23 cm long until the first flower, pink, pruinose; bracts elliptical to oblong-elliptical, 12 ‒ 18 mm × 6 ‒ 10 mm, obtuse at the apex, cuneate-attenuate at the base, flat, green, pink with age; flower bracts subimbricate in young cincinnus, ovate, obovate, oblong, elliptical, to oblong-elliptical, 8.5 ‒ 16 mm × 5 ‒ 9 mm. Flowers on a turbinate pedicel, 3 ‒ 7 mm × 1.5 ‒ 2 mm, pruinose. Calix 5-lobate, lobes unequal, the largest oblong, 9.5 ‒ 13 mm × 4.2 ‒ 6 mm; the smaller oblong, 8 ‒ 10 mm × 2.5 ‒ 3.5 mm, apex acute, mucronate. Corolla gamopetalous, 5-lobate, lobes oblong, 7 ‒ 9 mm × 2.5 ‒ 3 mm, apex acute, yellowish-white with an abaxial red spot in the middle; scales red. Stamens 10, 5 antipetalous, 2.5 ‒ 4 mm long, 5 antisepalous, 5 ‒ 6.5 mm long. Nectaries narrow, transversely elliptical, ca. 0.5 mm long, yellowish. Ovary ca. 6 mm, style ca. 2 mm long. The fruit a follicle, ca. 8 mm long, seeds numerous, narrowly obovoid.

Distribution and habitat:— Pachyphytum rogeliocardenasii is endemic to the northwest region of Queretaro, near the border with Guanajuato where one population that lives on vertical walls of limestone sedimentary rock has been recorded in the canyon of the Atarjea river. The climate of the region is subhumid, semi-warm (sensu García 1973). The vegetation corresponds to the deciduous tropical forest (sensu Zamudio et al. 1992). Some of its elements are Celtis iguanaea and various representatives of Leguminosae. The walls where the plant grows are also habitat by populations of Agave sp. , Hechtia sp. , Echeveria sp. and Sedum corynephyllum .

Additional material examined (paratypes):— MEXICO. Querétaro: municipio Arroyo Seco, Cañon de Atarjea , sobre paredes en el lecho del río, 3 km al SW de Santa María de Cocos, 800 m elevation, 21°18’24.64” N, 99°38’26.54” O, 24 May 2015, R. Torres C. 17902, A. Zaldívar & V. Salinas ( IEB!, MEXU!, QMEX!) ; cerca de 2.9 km al SW de Santa María de Cocos , 800 m elevation, 21°18’24.64” N, 99°38’26.54” O, 16 June 2015, E. Pérez 6605 ( IEB!) .

Phenology:—The new species is suffrutex and perennial, so it can be seen with the leaves arranged near the apex of the hanging stems throughout the year. It has been registered flowering in November and eventually in June.

Conservation status:— Pachyphytum rogeliocardenasii is assigned in the category of Endangered, based on the proposal of the International Union for Conservation of Nature, under the Criterion B, sub-criteria 1a and 2a; and Criterion C, sub-criteria 2a (EN B1a+2a; C2a) ( IUCN, 2012). It is estimated that the only known population has less than 1000 mature individuals and its area of occupation is very small (ca. 150 m 2).

Etymology:—The specific epithet is dedicated to the memory of Rogelio Mariano Cárdenas-Soriano (Cuautla, Morelos, 1961 - Pátzcuaro, Michoacán, 2010). Rogelio worked as a scientific illustrator in the Bajío Regional Center of the Institute of Ecology, A.C., from 1995 until his death, and elaborated a series of illustrations, published in the fascicles of Flora del Bajío and of adjacent regions; he also drew new taxa for science, which were published in various specialized journals in botany.

Discussion:—Morphologically, Pachyphytum rogeliocardenasii is classified in Section Pachyphytum (sensu Moran 1968, 1971) because it possesses the following set of characters:

—The bracts are narrowly imbricate in the young cincinnus, long and bidentate at the base.

—The calyx exceeds the corolla, the segments of the first whorl are unequal between them, and the longer ones are imbricated before and after anthesis.

—The white petals are spotted deep red on the inner side of the width of the petal, almost completely covering the scales, forming together with the pistil and filaments a conspicuous red center on the flower.

—Short pedicels (2 ‒ 8 mm).

—The basal leaf blades are elliptic to obovate and less than 2 ‒ 5 times wider than thick.

Pachyphytum rogeliocardenasii is morphologically similar to P. garciae . It differs from the latter species by the leaves being up to 1.3 cm longer and 0.5 cm wider ( Fig. 3 ), peduncle bracts 6 ‒ 7.5 mm longer and 2 ‒ 4.5 mm wider and similarly, the calyx lobes are also longer and wider. Finally, the lobes of the corolla in P. rogeliocardenasii are white abaxially and with an abaxial red spot in the middle, unlike those of P. garciae , which are light pink abaxially and spotted reddish ( Table 1).

The classification of Pachyphytum garciae in any of the sections in which Pachyphytum is subdivided ( Pérez-Calix & Glass 1999, Thiede 2003) is uncertain. Nevertheless, this species, like P. rogeliocardenasii , shows a great similarity with the section Pachyphytum . A molecular phylogenetic study is required to unravel the systematics of this group.

Figures

FIGURE 1. Pachyphytum rogeliocardenasii E. Pérez-Calix & R. Torres, sp. nov. A) Habit; B) Variation of the foliar lamina and cross section of the leaf blade; C) Cincinnus lateral view; D) Cincinnus adaxial view; E) Flower; F) Flower dissection; G1) Petal abaxial view; G2) Petal lateral view; H) Seed. (A‒H based on E. Pérez 6616, IEB)

FIGURE 2. Pachyphytum rogeliocardenasii: A) habit; B) petal color; C) calyx lobes; D) inflorescence peduncle and floral bracts. P. garciae: E) habit; F) petal color; G) calyx lobes; H) inflorescence peduncle and flowers bracts.

FIGURE 3. Leaf shape and size variation of: A) Pachyphytum rogeliocardenasii; B) Pachyphytum garciae.