Lepidium colombianum Al-Shehbaz, 2025

Lepidium colombianum Al-Shehbaz View in CoL , sp. nov.

Diagnosis:— Lepidium colombianum differs from L. bipinnatifidum , its most closely related species of northern South America by having glabrous cauline leaves, caducous sepals, puberulent fruiting pedicels all around, and biennial or short-lived perennial habit.

Type:— COLOMBIA. Cundinamarca. Municipio de Chia Via a La Caro, 18 May 2007, J. L. Fernández-Alonso and A. Fernández 25174 ( holotype, MA-848650). Figures 1 and 2.

Description:—Herbs, biennial or perhaps short-lived perennial without caudex, puberulent on stems and pedicels. Trichomes retrorse to spreading, 0.1–0.2 mm long. Stems 18–25 cm tall, erect to ascending, branched above middle, puberulent. Basal leaves rosulate, 1-pinnatisect, withered later; lateral lobes 2–5 on each side, linear to narrowly lanceolate, entire; petiole 3–5 cm long, glabrous; middle cauline leaves 1–3 cm long, pinnatifid and with 2–4 lateral lobes on each side, glabrous, strongly auriculate at base; upper leaves entire, strongly auriculate, glabrous or sparsely puberulent on midvein abaxially. Racemes many flowered, somewhat lax in fruit, to 10 cm long in fruit; rachis straight, puberulent as stem; fruiting pedicels slender, ascending to divaricate, arcuate, 3–5 mm long, slightly margined, terete, 3–4 mm long, 0.2–0.3 mm wide, puberulent all around. Sepals oblong, 1–1.2 mm long, caducous, glabrous, margin and apex white; petals white, linear, ca. 0.5× 0.07–0.08 mm; claw absent; stamens 2, median; filaments 1–1.2 mm long; anthers ovate, ca. 0.3 mm long; nectar glands 4, toothlike, 1 on each side of median filament base; ovules 2 per ovary. Fruits dehiscent, obovate, 3–3.5 × 2–2.5 mm, angustiseptate, narrowly winged apically, not veined, glabrous, apex emarginate; apical notch ca. 0.5 mm deep; septum complete; style ca. 0.25 mm long, included in apical notch. Seeds reddish brown, ovate, wingless, 1.1–1.2 × 0.8–0.9 mm; cotyledons incumbent, entire.

Distribution:— Endemic to Colombia and known thus far only from the type collection. Unfortunately, nothing is known about it phenology, distribution elsewhere in the country, and its overall variation.

Discussion:— Lepidium colombianum closely resembles Lepidium bipinnatifidum Desvaux (1815: 177) , a species widespread from Venezuela and Colombia south into Ecuador, Peru, Brazil, Bolivia, and northern Argentina. Both have pinnatisect lowermost cauline leaves, auriculate middle and uppermost cauline leaves, narrowly margined or winged fruiting pedicels that are arcuate, usually obovate fruits 2.5–3.5 mm long, rudimentary petals only 0.3–0.5 mm long, and minute styles included in the shallow apical notch. The new species differs by being a biennial or short-lived perennial without a caudex and having caducous sepals, fruiting pedicels puberulent all around, glabrous leaves, entire uppermost cauline leaves, and pinnatifid middle cauline leaves with 2–4 lateral lobes on each side. By contrast, L. bipinnatifidum is a long-lived perennial usually with woody caudex and has persistent sepals till fruit maturity or tardily caducous, fruiting pedicels puberulent adaxially and glabrous abaxially, puberulent and pinnatifid or incised cauline leaves with 3–6(–8) lateral lobes on each side.

Lepidium colombianum resembles some disjunct southern South American species, such as L. pedersenii Al-Shehbaz (2010: 156) , L. spicatum Desvaux (1815: 178) , and L. tandilense Boelcke (1964: 521) , especially in habit and leaf margin and in having rudimentary petals, two stamens, and glabrous small fruits with shallow apical notch, though it is unlikely related to them. From these, it is readily distinguished by having obovate (vs. orbicular to broadly elliptic fruits 3–3.5 (vs. 2 –2.5 mm long), and longer (3–3.5 vs. 1–2(–2.5) mm) fruiting pedicels puberulent all around (vs. only adaxially).

The centers of greatest diversity of Lepidium are in central and southwest Asia and the Andes of South America, and they have 77 species (56 endemic) and 58 spp. (32 endemic), respectively. Argentina has the highest number of species: endemics (27: 9), followed by Chile (19: 6), Bolivia (16: 6), Peru (15: 5), Ecuador (9: 1), Brazil (6: 1), and Colombia (6: 1). Paraguay, Uruguay, and Venezuela have no endemics ( Table 1), and the remaining South American countries (French Guiana, Guyana, and Suriname) have no native Lepidium species.

Little is known about seven of the 32 country-endemic South American species because they are known each only from their type collections. These are L. arequipa Al-Shehbaz (2017: 403) , L. colombianum , L. cuscoense Al-Shehbaz (2010: 150) , L. grandifructum Hitchcock (1945: 82) , L. lapazianum Al-Shehbaz & Beck in Al-Shehbaz (2017: 405), L. stephan-beckii Al-Shehbaz (2017: 412) , and L. weigendii Al-Shehbaz (2023: 297) .