Draba ancashensis Al-Shehbaz, A.Cano

Al-Shehbaz, Ihsan A., Cano, Asunción & Trinidad, Huber, 2019, Draba ancashensis (Brassicaceae; Cruciferae), a new species from Peru and a key to the Peruvian species of the genus, Phytotaxa 395 (3), pp. 235-240 : 235-237

Draba ancashensis Al-Shehbaz, A.Cano & Trinidad. sp. nov.

Diagnosis:— Draba ancashensis is easily distinguished from the other Peruvian species of the genus by having woody lower stems, cauline leaves adaxially with simple trichomes and abaxially with stellate, 12-branched trichomes, fully bracteate racemes, white flowers, and persistent sepals.

Type:— PERU. Ancash: Prov. Recuay, Ichic Potrero , 5 Aug 2017, 4689–4832 m, 9°50´43.3”S, 77°5´55.9”W, Asunción Cano, Huber Trinidad, Sebastián Riva & Niels Valencia 22419 (holotype: USM-304594!; isotype, MO-6866608!). Figures 1–3 .

Description: —Plants small subshrubs, not scapose or pulvinate; caudex absent. Stems 10–15 cm tall, 4–5 mm in diam. above base, erect to ascending, several to many branched above, woody, naked at base and smooth bark exposed, covered at middle with remnants of outer stem layers and leaf remains, moderately pubescent with sessile, stellate trichomes with 2- or 3-branched rays and fewer simple trichomes to 0.6 mm long; stem branches terminated in fruiting racemes of previous years, below which produced one or two branches of subsequent year. Basal leaves absent; leaves cauline, persistent, sessile, densely imbricate; petiole absent; leaf blade oblong to oblong-ovate, 5–10 × 2–3.5 mm, abaxial surface densely pubescent with almost exclusively short-stalked stellate trichomes 0.2–0.5 mm in diam., these with principal 4 rays each (2- or)3-branched and trichome appearing 12-branched, rarely few Y-shaped trichomes present, adaxial surface with antrorsely appressed simple trichomes 0.5–0.8 mm long, base cuneate, margin entire, ciliate near base with simple and sometimes fewer forked trichomes to 1 mm long, apex obutse to subacute. Racemes bracteate throughout, 5–15-flowered, corymbose, dense, slightly elongated in fruit; peduncle 5–10 mm long; rachis pubescent as stem, straight; bracts similar to cauline leaves in shape and indumentum, gradually reduced in size upwards; lowermost fruiting pedicels divaricate to ascending, straight, 4–5 mm long, densely hirsute all around with simple, Y-shaped, and fewer 3- or 4-rayed stalked trichomes. Sepals green, oblong, 3–3.5 mm long, ascending, persistent through fruit maturity, base not saccate, densely stellate pubescent outside; petals white, spatulate, 4–4.5 × 1.4–1.7 mm, caducous, apex emarginate; claw only slightly differentiated from blade, ca. 1.5 mm long; filaments white, 2–2.5 mm long, slightly dilated at base; anthers ovate, 0.4–0.5 mm long, obtuse at apex; nectar glands confluent, subtending bases of all filaments; ovules 12–16 per ovary. Fruit oblong to oblong-ovate, 5.5–7 × 2.5–3 mm, strongly flattened, not twisted, sessile; valves puberulent with simple minutely staked or subsessile forked trichomes 0.05–0.25 mm long, not or obscurely veined, obtuse at apex and base; style 0.4–0.7 mm long; stigma entire, narrower than style. Seeds brown, ovate, strongly compressed, 1–1.1 × 0.6–0.7 mm, wingless.

Distribution: —Endemic to the Peruvian department Ancash and known thus far only from the type collection above.

Etymology: —The species epithet is named after the department Ancash.

Habitat: —Rocky crevices and outcrops at mountain tops.

Discussion: — Draba ancashensis is endemic to Peru and known thus far only from the type collection. It resembles the three Peruvian-endemics D. cajamarcaensis , D. matthioloides , and D. peruviana (see key for authors of species names), in having sessile, exclusively cauline leaves, woody lower stems, leaves abaxially pubescent with stellate trichomes, and fully bracteate racemes. It differs from all of them in the persistent (vs. readily caducous) sepals. From D. cajamarcaensis , it is easily distinguished by having stems and raceme rachis pubescent with simple and stellate (vs. malpighiaceous) trichomes, cauline leaves pubescent with stalked (vs. sessile) stellate trichomes with branched rays and appearing 12-branched (vs. cruciform trichomes with at least some rays unbranched), and oblong to oblong-ovate (vs. narrowly lanceolate) fruit. It differs from D. peruviana in having adaxial leaf surface with primarily simple (vs. stellate) trichomes, entire (vs. dentate) leaves, smaller petals 4–4.5 × 1.4–1.7 (vs. 7–l0 × 3–3.5) mm, and shorter styles 0.4–0.7 (vs.1.5–3) mm long. Finally, it separated from D. matthioloides by its adaxial leaf surface with exclusively simple (vs. stellate) trichomes, white (vs. yellow, orange, or purple) petals 4–4.5 × 1.4–1.7 (vs. 6–10 × 2.5–3.5) mm, 12–16 (vs. 24–38) ovules per ovary, and styles 0.4–0.7 (vs. (0.5–) 3–10) mm long.

Figures

FIGURE 1. Draba ancashensis.—A. Portion of plant.—B.A trichome from abaxial leaf surface.—C. Petal.—D. Infructescence after fruit dehiscence.—E. Fruit. Drawn by Al-Shehbaz from the isotype (Cano et al. 22419—MO-6866608).