Rosales, Jimeno-Sevilla & Hernández-Campos & Rosales-Martínez & Posadas-Trejo, 2025

Jimeno-Sevilla, H. David, Hernández-Campos, J. Daniel, Rosales-Martínez, C. Santiago & Posadas-Trejo, Karla Gabriela, 2025, A new species of Echeveria ser. Nudae (Crassulaceae) from Jalisco, Mexico, and a new combination, Phytotaxa 697 (3), pp. 234-244 : 238-242

Echeveria machucae Jimeno-Sevilla, D.Hernández & Rosales , sp. nov. ( Figs. 1–4 )

Type:— MEXICO. Jalisco: El Jacal, municipio de Atenguillo, ladera con exposición sureste en bosque tropical caducifolio, 1580 m, 10 January 2023, J. D. Hernández-Campos, S. Rosales, J. A. Machuca, K. Posadas-Trejo & F. J. Ramírez 271 (holotype IBUG!, isotypes MEXU!, XAL!, ZON!).

Diagnosis: — Echeveria machucae is similar to E. flammigera by having a suffruticose habit, very minutely papillose surface, and similar corolla length; however, it differs from the latter in its wider stems (0.8–1.2 vs. 0.3–0.5 cm), stems papillose to the apex (vs. not papillose), larger leaves (3.0–4.2 × 1.3–1.9 vs. 1.0–1.5 × 0.5–1.0 cm), racemose to occasionally thyrsiform inflorescences (vs. compactly racemose, never thyrsiform), longer pedicels (7.0–22.0 vs. 4.0–6.0 mm), petals bright orange-yellow (vs. orange to reddish orange, never yellow), wider nectary scales (2.0–2.4 vs. 1.0– 1.5 mm) and yellow nectary scales (vs. whitish). It is also similar to E. multicaulis in the stem size, leaf length, and number of flowers per inflorescence; nevertheless, the former differs in the leaf surface very minutely papillose (vs. glabrous but not papillose), stem surface with prominent scars and papillose to the apex (vs. with prominent irregular hexagonal shaped sections around leaf scars), inflorescence laxly racemose to occasionally thyrsiform (vs. shortly racemose), corolla length (14.0–16.0 vs. 8.0–10.0 mm), and petals bright orange or yellow (vs. carmine to scarlett with orangish-yellow margins, never totally orange or yellow).

Description: —Plants perennial, suffruticose, entirely glabrous, to 99.0 cm tall with inflorescence, profusely branching. Roots fibrous, the adventitious ones anchoring to the substrate. Stems to 92.0 cm long, 0.8–1.2 cm in diameter, at first suberect, later decumbent, somewhat rugose, with small bumped scars, papillose to the apex, greyish. Rosettes terminal, 3.0–7.0 cm in diameter, lax. Leaves 3.0– 4.2 cm long, 1.3–1.9 cm wide, 0.3 cm thick, obovate to oblanceolate, rounded at the apex, mucronate, more or less horizontally spreading to ascending, minutely papillose, light green, entire, with reddish or purplish margins. Inflorescences lateral, 1 (–2) per rosette, racemose to occasionally thyrsiform, to 35.0 cm long. Peduncle 9.0– 26 cm tall, 0.3–0.6 cm thick at the base, yellowish green. Peduncle bracts up to 11, alternate, 1.5–2.0 cm long, 0.5–0.9 cm at the widest part, similar to leaves in shape and color. Bracteoles 0.7–1.0 cm long, 0.4 cm at the widest part, 0.3 cm wide at the base, lanceolate. Flowers 7–18 per inflorescence, pentamerous. Pedicels 7.0–22.0 mm long, thickened distally, usually bearing 2 bracteoles, with a rough surface, light green. Sepals 5, almost equal, 5.0–13.0 mm long, 2.5–4.0 mm wide at the base, long-triangular, light green. Corolla 14.0–16.0 mm long, 8.0–9.0 mm wide at the base, tubular, pentagonal. Petals 5, 13.0–15.0 mm long, 4.0–5.0 mm wide, lanceolate, finely acute at apex, ventrally concave, dorsally keeled, bright orange or yellow. Nectary scales 2.0– 2.4 mm wide, reniform, yellow. Gynoecium 1.0– 1.2 cm long, with 5 carpels, pale yellow. Ovaries 5.0 mm long, 2.0 mm wide. Styles 5.0 mm long, greenish-yellow. Stigmas greyish-green. Stamens 10, pale yellow, the epipetalous 5.0–6.0 mm long, the antesepalous 7.0–9.0 mm long. Anthers ca. 1.5 mm long, ovoid, yellow. Fruits polyfollicular, dorsally dehiscent, ascending, pale brown. Seeds inconspicuous, brownish.

Distribution and ecology: — Echeveria machucae is currently known only from the type locality at El Jacal, Atenguillo municipality, Jalisco, within the Sierra Madre del Sur biogeographic province. It grows as a dense shrub composed of several independent specimens, on slopes with a southeast exposure along a permanent stream, thriving on the organic matter that accumulates on extrusive igneous rocks. It occurs in a small patch of deciduous tropical forests surrounded by pine-oak forest, with Agave aff. schidigera Lemaire (1861 : pl. 289), Echeveria colorata Walther (1972: 91) , Tillandsia pamelae Rauh (1986: 117) , Dioscorea minima Robinson & Seaton (1893: 105) , Opuntia sp. , Bursera sp. , and other species at an elevation of 1550–1600 m. The climate in the area is temperate sub-humid with summer rains and temperatures of 4.0–29.9 °C, with an average annual rainfall of 1067 mm ( IIEG 2022). While collecting the type specimens of E. machucae in January, two commensalistic interactions were observed ( Fig. 3 ): the first one involved lynx spiders ( Peucetia sp. ) found in the inflorescences, waiting for floral visitors and pollinator arthropods; the second one represents the first record, to our knowledge, of a Tillandsia species growing as an epiphyte on one of the stems. This is noteworthy because only few ecological interactions in the genus Echeveria have been reported.

Phenology: —The development of inflorescences starts in November, with the first opening flowers from mid December to mid January. The dehiscence of follicles takes place between mid-January and the first week of February.

Etymology: —The authors are pleased to name this species in honour of José Antonio Machuca Núñez (1960–) ( Fig. 3 ), a dear friend, tireless collector, outstanding explorer, and discoverer of numerous new plant species. He spent nearly a decade searching for the habitat of the new species in the Atenguillo-Mascota-Talpa area until he found it. He was kind enough to guide us to the type locality in order to document mature specimens for the description of this new species.

Conservation status: — Echeveria machucae only grows along approximately 60 linear meters on the slope of a riverbed, where we observed only around 15 dense shrubs. In recent years, the surrounding area has been significantly affected by deforestation, designated for Agave maximiliana Baker (1877: 201) crops used in the production of raicilla. This activity can alter the microclimates present in the riverbed, putting the population of E. machucae at risk. Based on the results of the EOO (0.0 km 2) and AOO (8.0 km 2), using 2 km wide cells and following the B1ab(iii) + B2ab(iii) criteria of the IUCN (2022), the species is categorized as Critically Endangered.

Echeveria longisepala (Kimnach) Rosales & D.Hernández, comb. & stat. nov. ≡ Echeveria pringlei (S.Watson) Rose var. longisepala Kimnach, Haseltonia 5: 51. 1998 [1997 publ. 1998], basionym. Type:— MEXICO. Jalisco: municipality of Mezquitic, east of mesa of San Andrés Cohamiata, 1800 m, 1987, J. Bauml & G. Voss 1932 (holotype HNT!, isotype MICH!)

Figures

FIGURE 1. Distribution map of Echeveria machucae and morphologically similar species, based on a template of biogeographic provinces sensu Morrone et al. (2017).

FIGURE 2. Echeveria machucae. A. Habit; B. Inflorescence detail; C. Decumbent stems; D, E. Rosettes. F. Bright orange flowers. G. Yellow flowers. H. Dissected flower. Photographs by Santiago Rosales.

FIGURE 3. Echeveria machucae. A. José Antonio Machuca Núñez holding a piece of E. machucae; B. Peucetia sp. waiting for floral visitors and pollinator arthropods on E. machucae flowers; C. Tillandsia sp. growing on a stem of E. machucae. Photographs by Santiago Rosales (A and C) and Francisco Javier Ramírez Maravillas (B).

FIGURE 4. Echeveria machucae. A. Plant with inflorescence; B. Flower; C. Carpels; D. Corolla lobes with stamens; E. Leaf, with upper side and transversal cuttings. Illustration by H. David Jimeno-Sevilla (based on the type material).