Calliandra pilocarpa A. E. Estrada, Rebman & Villarreal, 2019

Castillón, Eduardo Estrada, Rebman, Jon P. & Quintanilla, José Ángel Villarreal, 2019, Astragalus comonduensis and Calliandra pilocarpa (Fabaceae), two new species from Baja California Sur, Mexico, Phytotaxa 391 (1), pp. 57-68 : 64-65

Calliandra pilocarpa A. E. Estrada, Rebman & Villarreal , sp. nov. ( Fig. 2 (A–F) & Fig. 3 )

Morphologically similar to C. peninsularis , but differs in stem pubescence, persistence of stipules, peduncle size, number of flowers per capitulum, bract size, calyx and corolla pubescence, corolla shape, pod suture width, and seed size.

Type:— MEXICO. Baja California Sur (Municipio Mulegé): Sierra Guadalupe: West of Mulegé: Cañada El Guano, just west of Rancho San Sebastian , 27°00’13’’N, 112°25’48’’W, alt. ca. 900 m, 26 October 1997, J. Rebman 4553, with B. Hollingsworth (holotype SD 141639 !; isotypes BCMEX 9220 , HCIB 11711 , UCR 109221 ) .

Plant shrubby up to 1.2 m tall. Stems woody, light brown, grooved, densely arachnoid-pubescent, the trichomes white (as in all structures), straight, sinuous and curly, 0.2–1.3 mm long, the shorter ones the denser, mixed with slightly curved or almost straight longer ones, all of them entangled. Stipules 6–7 mm long, linear-lanceolate, densely whitepubescent abaxially, glabrate adaxially, persistent. Leaves bipinnate-paripinnate, pinnae (2–)5–6 pairs, similar in size, sometimes, the middle ones longer; petiole 6–11.5 mm long, pilose-pubescent, leaf rachis 2.2–5 cm long, pilose-pubescent, pinna rachis 1.9–4.9 cm long, pilose-pubescent; leaflets petioluled, petiolule 0.2–0.3 mm long, light-green, (13-)18–20 pairs per pinna, 6–11.5 × 1–1.7 mm, the longest ones in the middle of the pinna rachis and gradually shorter in size to both ends, oblong, inequilaterous-cordate and, wider at base to narrowly ovate, lance-ovate, acute at apex, with a small mucro, 0.01 mm long, lead color and glabrous or sparsely pilose with 0.4–0.7 mm long, curly or sinuous trichomes or olive green, covered with a waxy-lead color veil adaxially, pilose or densely pilose-pubescent, remaining so and with no waxy-lead color veil abaxially, venation palmate-pinnate, the midvein little displaced forwardly, charged to one side more than another, and dividing the blade in a 1:2 ratio, slightly prominent adaxially, more prominent and raised abaxially. Inflorescences, peduncles 3.8–6 cm long; capitulae 2–8 flowered; bracts 1–1.6 mm long, lanceolate, glabrous and reddish adaxially, sparsely-pilose abaxially; pedicels 1–1.5 × 0.5–0.8 mm, glabrous, sometimes hidden by the dried persistent corolla; perianth pentamerous, flowers actinomorphic; calyx 2–2.2 × 1.2–1.4 mm, campanulate, the tube 1–1.2 mm long, the teeth 1–1.3 ×x 0.8–1 mm, triangular, densely pilose-pubescent, persistent to fruit maturity, and breaks due to the widening of pedicel and fruit during development; corolla gamopetalous, campanulate, funnelshaped, 6.1–6.5 × 2–3.5 mm, the tube 2.5–3.8 mm long, the teeth 1.2–1.6 mm, triangular, all densely pilose-pubescent as in stems; androecium 18–24-merous, the sheath 5.5–7 mm long, the free portion 14–23 mm long, red; ovary elliptic. Pod 1–2 per capitulum, erect, 5.8–7.5 × 0.7–0.9 cm, oblong, gradually narrow basally and abruptly so at the apex, the sutural keels 1–1.3 mm wide, the valves light-brown, opaque, linear, cross nerved, shallowly reticulated and most evident near sutures, densely and permanently pilose-arachnoid or densely-pilose, the trichomes entangled overall, raised over the seeds, slightly constricted at interseminal spaces; seeds 7–8 × 5–6.5 mm, rhombic-elliptic to rhombicobovoid, base cuneate but somewhat rounded, apex abruptly or gradually acute, plumpy-inflated, the testa hard, dull, tan, speckled with black, pleurogram black stained, linear-filiform.

Distribution and habitat: —As far as we know, Calliandra pilocarpa occurs only in a restricted part of northern Baja California Sur in the Sierra Guadalupe ( Fig. 4 ), associated with vegetation dominated by Prosopis palmeri S. Watson (1889: 48) , Aralia scopulorum Brandegee (1889: 165) , Prunus ilicifolia (Nutt. ex Hook. & Arn.) D. Dietr. (1842: 43) , Bernardia viridis Millsp. (1889: 223) , Acalypha comonduana Millsp. (1889: 222) , Euphorbia xanti Engelm. ex Boiss. (1862: 62) , and Nolina palmeri var. brandegeei Trel. (191 2: 50), inhabiting slopes and canyons with volcanic substrate.

Etymology: —The epithet of this new species refers to the pilose vestiture of the fruits as they have white, dense and entangled pubescence remaining evident on the fruit valves even after maturing and opening.

Phenology: —Based only on a few known specimens, flowering presumably occurs from August to November and in April, and fruiting from September to November and possibly in May.

Additional specimens examined (paratypes): — MEXICO. Baja California Sur (Municipio Mulegé): Sierra de Guadalupe: El Barco: bajada al Cañón de San Pedro, 26°53’24”N, 112°26’47”W, alt. 980 m., 28 November 2002, M. Domínguez L. 3214 (SD 160093!, HCIB 18096). Sierra Guadalupe: West of Mulegé: Cumbra de San Pedro between Ex-mission Guadalupe and San Juan de las Pilas, 26°53’50”N, 112°26’08”W, alt. ca. 1280 m, 29 April 1998, J. Rebman 5214, with J.L. Zuniga (SD 142316).

Notes: —The inflorescences of Calliandra pilocarpa are lateral and developed along its primary leaf-axis, below the foliage apex which put this new species in the C. sect. Androcallis ( Barneby 1998: 21). This is reinforced by its distichous phyllotaxy, bipinnate leaves with minute leaflets, and non-spinescent stipules. Of the 35 species of Calliandra distributed from the southern United States, Mexico and Central America, only three that are currently recognized are recorded from the peninsula of Baja California, C. eriophylla , C. peninsularis , and C. californica . Calliandra eriophylla is distinguished from the other two species by its obviously bicolored (pink and white) androecium. Morphologically, the other two species can be distinguished by the number of pairs of pinnae (5–7 in C. peninsularis , 2–4 in C. californica ) and by the number of pairs of leaflets (16–21 pairs in C. peninsularis and 5–12 or rarely more in C. californica ) per pinna. Ecologically, these two species generally inhabit different types of vegetation and different elevations. Calliandra peninsularis is most commonly associated with oak or oak-pine forest at relatively high elevations, ranging from 1000–1800 m, with a restricted distribution between 22°– 24°N, while C. californica typically inhabits more arid sites at lower elevations ranging 5–550 m and is widely distributed throughout most of the peninsula and on various adjacent islands. The new species is morphologically closer to Calliandra peninsularis as both share similarities in leaf size, pinna rachis size, size and shape of leaflets, and stamen number. However, these species have significant differences in several morphological characters ( Table 2).

The substantial differences in the peduncles, bracts, pedicels, calyx, calyx teeth, pod, and seeds, in addition to the different number of flowers per capitulum, and corolla shape, show clear and obvious differences between this new species and Calliandra peninsularis . Calliandra pilocarpa is easily distinguished by its persistent stipules, white canescent-pilose foliage, campanulate corollas, and its white densely pilose-canescent, opaque pods. The calyx and corolla of Calliandra pilocarpa are completely densely white pilose-pubescent with entangled trichomes. In Calliandra peninsularis the calyx is puberulent, but the trichomes are mostly restricted around the orifice and the corolla is minutely strigulose. In Calliandra californica the calyx is pilosulous overall or glabrescent on the lower half or completely glabrous, and the corolla is glabrous, narrow campanulate to evidently cylindric, minutely strigulose, or rarely more densely pilosulous ( Barneby, 1998).

Figures

FIGURE 2. Calliandra pilocarpa, A) Stipules and pubescence. B) leaf. C) Complete flower showing calyx, corolla, stamens and style, note the characteristic dense pubescence in both, calyx and corolla. D) leaflet and venation. E) Fruit. F) Seed. Illustration by Callie Mack.

FIGURE 3. Holotype (SD 141639) of Calliandra pilocarpa (previously determined as Calliandra peninsularis).

FIGURE 4. Distribution of Astragalus comonduensis and Calliandra pilocarpa in Baja California Sur, Mexico.