Opuntia caboensis Mercado & León de la Luz, 2021

Muñoz, Fermín Mercado, Luz, José Luis León De La, Rebman, Jon P., Narváez, Alfonso Medel & Ramos, Rafael Campos, 2021, Two new species of nopal (Opuntia, Cactaceae) from the Baja California Peninsula (Mexico), Phytotaxa 508 (3), pp. 266-278 : 272-275

Opuntia caboensis Mercado & León de la Luz , sp. nov. Figs. 4 , 5 .

Opuntia caboensis is similar to O. comonduensis from the eastern mountains and coasts of Baja California Sur, but has smaller cladodes and more velvety tomentose texture; moreover, shorter and fewer spines, these located in the upper third of the pads, or almost absent, also it is diploid versus tetraploid.

Type: — MEXICO. Baja California Sur: municipio La Paz, paraje La Piedra Bonita, ladera de exposición al Sur en el Cañon de La Burrera , 3.5 km al SW del Valle de La Laguna , 23.521542° N, 109. 999775° W, 1102 m, transición bosque de encino y selva baja caducifolia, 14 May 2008, J.L. León de la Luz 08-087 (holotype HCIB 31865!, isotypes to be deposited at MEXU!) .

Erect and ascending plants up to 2 m tall, evenly branched; basal cladodes dark brown, woody in appearance, lacking spines, upper and new cladodes yellowish-green, in times of water stress the areolar zone is pigmented with purple spots, particularly in the upper portion of the pads, sometimes covering the whole pad. Young cladodes with conical recurved-descending ephemeral leaves, these born at the base of the areoles, up to 5 mm long, reddish turning yellowish-green, rostrate, circular areoles with felt or gray-white wool and numerous yellow glochids in the center up to 1.5 mm long; pad epidermis with velvety texture to touch. Mature cladodes obovate to orbicular, yellowish green when hydrated, 17–20(–23) cm long, 8–14 cm wide, pad surface still somewhat velvety to touch throughout, but turning papillose on older cladodes; each with 2–9 diagonal series of areoles 0.7–1 cm separated from each other, oval or circular, 1–1.5 mm in diameter, with brown wool and yellowish glochids, when stressed purple spots appear around the areoles, at times forming obvious purple stripes on the surface of the whole cladode, numerous glochids 2 mm long, generally without spines, but when present 1–2(–3) straight, porrect, yellowish turning gray and only in the areoles of the upper third, or vestigial at the cladode margin, acicular to subulate, 1–2(–2.5) cm long. Flower buds on the cladode edge, rarely on the face of the cladodes, areoles in 5–6 semi-spiral series, with white-gray wool and small, yellow and glochids of uneven length, 1–3 mm long, more or less persistent; outer segments of the perianth in 3 series, pink or reddish turning yellow, persisting red in the central-upper part, the apical or superior areoles of the pericarpel all alike. Flowers rotate at anthesis, 5.5–7.5 cm in diameter, inner perianth segments yellow, 4–4.5 cm long, 1.2–1.5 cm wide, oblong, with denticulate upper margins, accuminate, outer segments sometimes pink to reddish on the apical mucro; stamens numerous, filaments yellow, sometimes ferruginous; anthers white; style white to yellow, 2.4–2.8 cm long; stigma the same color as the style or greenish, with 5–6 digitate lobes to 2 mm long, short rostrate; ovary cavity obovoid to obconic 4–7 mm long, 3–5 mm wide, with numerous ovules; pollen spherical to tetragonal, apolar, 60–90 µm in diameter, periporate, tectum reticulate, smooth walls, 10–14 circular pores, 12–19 µm in diameter; pericarpel velvety pubescent to touch, obconic 3.5–4.5 cm long, with 4–5 oblique series of areoles, with persistent and abundant glochids, small, yellow. Fruit ovoid to obovoid, 4–4.5(–5) cm long, 3–4 cm in diameter, both cuticle and pulp green, becoming somewhat yellowish when ripe after 5–8 months, outer wall 2–3 mm thick when fresh; receptacle variable, 0.4–0.6 cm deep; seeds semi-circular 3–4 mm in diameter, grayish in color. Chromosomal number 2n = 4X = 44 (F. Mercado Muñoz 490).

Paratypes:— MEXICO. Baja California Sur, municipio La Paz, camino de terracería San Antonio de la Sierra a rancho La Victoria , 23.623565° N, 110.916394° W, 1084 m, bosque de encinos, 17 May 2012, F. Mercado Muñoz 464 (to be deposited at ARIZ); municipio Los Cabos, inmediaciones de la ranchería La Cieneguita, Sierra San Lázaro, 23.238237° N, 109.952748° W, 772 m, selva baja caducifolia, 7 May 2013, F. Mercado Muñoz 526 (to be deposited at USON); municipio La Paz, Camino por la entrada a San Blas Sierra Las Calabazas, 23.8489°N - 110.1957°W, 373 m, 11 April 2013, F. Mercado Muñoz 513 (SD 265354); Municipio La Paz , Ensenada de Muertos , 40 m, 23.9781°N - 109.8371°W, 2 April 1952, R.V. Moran 3565 (SD 45886); Ensenada de Muertos , 23.9781°N - 109.8371°W, 40 m, 2 April 1952, G. Lindsay s/n (MEXU 45886); near Punta Frailes, 23.3698°N - 109.4389°W, 20 m, 4 April 1937, P.J. Rempel 320 (RSA 442409) ; 7 km W Rancho El Saltito, 23.2385°N - 110.1961°W, 150 m, 8 November 1971, G.A. Voss 1185 (SD 234104), near San Bartolo town, 23.7388°N - 109.8638°W, 439 m, 1 July 1973, A.C. Gibson 3004 (ARIZ 210374); 1 km SE Presa Santa Ines, 23.5441°N - 110.1359°W, 337 m, 17 May 1992, J.P. Rebman 1379 (BCMEX 5122); near rancho Alvaro Obregón, 23.8845°N - 110.2127°W, 90 m, 8 August 1994, J.P. Rebman 2488 (SD 138273); Sierra La Victoria, near Rancho La Concepción , 23.6448°N - 109.9071°W, 720 m, 3 February 1996, M.A. Baker 12163 (SD 139848); Sierra La Victoria , road La Concepción , 23.6338°N - 109.8883°W, 700 m, 5 February 1996, M.A. Baker 12173 (ASU 205475); 15 Km NE Cabo San Lucas , Arroyo El Tule , 22.9598°N - 109.8024°W, 6 m, 13 April 1977, J.A. Tonix 17 (MEXU 204340); Municipio Los Cabos , near San José del Cabo, 23.0663°N - 109.6651°W, 15 m, 25 March 1911, J.N. Rose 16470 (NY) .

Etymology: —The specific epithet is derived from the toponym “Región de Los Cabos” referring to the Cape region, the extreme southern extent of the Baja California peninsula. In turn, the epithet “Cabos” is also related to the two main towns in the area, Cabo San Lucas and San José del Cabo.

Distribution and habitat: —It should be noted that both of these new species overlap in their distributions in the Cape region’s mountains, specifically in the northern portion, an area called the Sierra de La Victoria (23.602°N). Both species are less common in the Cape’s southern mountains (Sierra San Lázaro, 23.252°N). However, in the eastern portion (slopes toward the Gulf of California) both species populations are more common than in the western slopes of the Pacific, where they are infrequent (see Figure 1 ).

Opuntia sierralagunensis occurs in dry tropical forest, from 400 m in elevation, to the limits with the oak woodland at about 1400 m. Regarding O. caboensis , it can be found most commonly between (10–) 100–1100 m in elevation. Both of these new species appear to have healthy populations in the elevation belt where they come into contact with the lowest oaks ( Quercus spp. ), around 700–900 m in the Sierra La Victoria. Apparently, the incidence of winter frosts restricts their distribution to higher elevations, although a sole plant of O. sierralagunensis was seen growing underneath pine trees at 1600 m. Also, the populations along the coastal strip are uncommon, however most of the herbarium specimens historically came from it.

Phenology: —The shrubby spreading habit of some O. sierralagunensis individuals might be attributed to the impacts of forage pressure from cattle that graze freely in the region, since some plants that were out of reach from cattle tended to have more erect growth habits and were taller, reaching up to 2 m. Although O. caboensis has a low number of spines, the areoles do have abundant glochids that might possibly act as a deterrent against some livestock grazing ( Fig. 5 A, B ).

For both species, flowering episode begins during the early spring (March), pollination seems to occur by native bees ( Augochloropsis sp. , and Diadasia sp. ) that are common visitors during mid-day, as well as Nitidulidae and Cantharidae beetles, and several ant species. Flowering ends during the dry and warm summer, when the water stress in the cladodes is noticeable. When the summer rains arrive (August-September), the plants rehydrate quickly and the fruits reach the last stage. In O. sierralagunensis the fruits ripen when they change their color from green to red ( Fig. 3F ), they are promptly consumed by birds and other fauna. For O. caboensis , the ever-green fruits show a noticeably low rate of setting and take more time to ripen, since they remain on the cladodes until winter or even into spring ( Fig. 5F ). In both cases, the seeds have a viability greater than 50%, but the majority of propagation for both species appears to be vegetative and occurs mainly from the detachment and rooting of the stem cladodes.

Also, for both species, the development of new stem cladodes occurs from the spring months and continues until the onset of summer rains. The flowers develop on these new pads the following spring, new pads sprout mostly from 2–3 year old pads. Some immature pads are heavily attacked by herbivorous insects (such as Moneilema sp. ) and others, possibly due to their soft texture and lack of any apparent structural defenses. The extreme results are deformities in the growth of these cladodes, and an eventual lack of vegetative growth. Due to the presence of cochineal ( Dactylopius opuntiae Cockerell ) colonies on some O. caboensis pads ( Fig. 5 B ), there might be additional impacts that affect fitness and growth of these individuals.

Finally, in respect to another important diagnostic character found in O. caboensis , when water stress begins during the dry season (in May), red spots develop and spread from each areole to cover wide strips on the surface of the cladodes, sometimes all of them ( Fig 5A ). This species shares this character with the partially sympatric O. bravoana , which has caused misidentifications by novice botanists. Table 1 shows additional taxonomical traits to take in account to separate them.

Conservation status: —Considering their irregular distributions in the tropical deciduous forest portions of the mountains of the Cape region, the relative low density of individuals in populations, as well as the herbivory pressure from cattle throughout their ranges, both O. sierralagunensis and O. caboensis could likely be considered as threatened or vulnerable species. Population studies should be conducted on both of these new species following IUCN and Mexican regulatory protocols in order to assess and categorize them accurately.

Figures

FIGURE 1. Geographical location of the study site. The Cape Region is the southernmost portion of the Baja California Peninsula in the state of Baja California Sur. The light gray area shows the mountainous terrain occupied mainly by the dry tropical forest and woodlands. Squares and circles show the location of collecting sites and observations for each new species, as well their respective type localities. Towns and ranges are cited in the text.

FIGURE 3. Opuntia sierralagunensis sp. nov. A. Spine pattern in a mature cladode; B. Lustrous condition of the cladodes; C. Pericarpel with floral buds, note long setaceous glochids in the upper areoles; D. Flower showing yellow tepals, with red to pink spots at tips: E. Flower longitudinally cut, there are two color morphs of the styles, white and red; F. Fruits in the transition from immature (green) to mature (red).

FIGURE 4. Opuntia caboensis sp. nov. A. Growth habit of the plant, and details of cladode shape and spine pattern, flower, and fruits. B. Detail of epidermis with delicate trichomes in the epidermis that give a velvety texture, and a young areole. C. Detail of a flower cut longitudinally, showing the pistil and stamen arrangement. D. Longitudinal cross-section of a ripe fruit showing receptacle and seed density. E. Detail of young areole with glochids and two emerging spines.

FIGURE 5. Opuntia caboensis sp. nov. A. Cladodes with red spots when stressed during the dry season; B. Cladode with few spines only in the upper third, and the presence of cochineal. Note also the velvety stem surface; C. Pericarpelar view; D. Flower view; E. Longitudinal cut of the flower, note greenish to yellowish color of the pistil; F. Mature fruit after ca. 8 months of development.