Mancoa Wedd., 1859

Al-Shehbaz, Ihsan A., Cano, Asunción, Machahua, Miguel, Roque, José & Mazzei, Piero, 2025, Mancoa chontaensis, a new species from Peru, and a synopsis of the genus Mancoa (Halimolobeae; Brassicaceae), Phytotaxa 701 (1), pp. 121-125 : 123-124

Mancoa Wedd. , nom. cons., non Rafinesque (1836: 56), nom. rej.

Type: Mancoa hispida Wedd.

Hartwegiella Schulz (1933: 187) .

Herbs, annual, biennial, or perennial. Trichomes forked or dendritic, sometimes mixed with simple ones, rarely absent. Multicellular glands absent. Stems decumbent or ascending to erect, few to several from base, usually branched above. Basal leaves petiolate, often rosulate, simple, 1- or 2-pinnatisect, sometimes pinnatifid to pinnatipartite, dentate or ultimate lobes subentire; cauline leaves sessile or short petiolate, auriculate or not, dentate to pinnately lobed. Inflorescence several- to many-flowered raceme, fully bracteate or ebracteate, elongated or not in fruit, rarely flowers on solitary pedicels originating from axils of rosette leaves; rachis straight; fruiting pedicels ascending to divaricate, persistent. Sepals ovate to oblong, free, deciduous or persistent, spreading or ascending, pubescent, base of lateral pair not saccate; petals white, longer than or subequaling sepals; blade obovate to spatulate, apex obtuse; claws slightly differentiated from blade, shorter than sepals, glabrous, unappendaged; stamens 6, erect to ascending, slightly tetradynamous; filaments wingless, unappendaged, glabrous, free; anthers ovate or oblong, obtuse at apex; nectar glands confluent, subtending bases of all stamens; ovules (12−)30−100 per ovary; placentation parietal. Fruits dehiscent silicles or rarely siliques, elliptic, ovate, oblong, or rarely linear, strongly angustiseptate to subangustiseptate-subterete, not inflated, unsegmented; valves papery, obscurely veined, pubescent or glabrous, not or slightly keeled, smooth, wingless, unappendaged; gynophore obsolete; replum rounded, visible; septum complete or rarely perforated, veinless; style distinct or obsolete; stigma entire. Seeds biseriate, wingless, ovoid to ellipsoid, plump; seed coat not mucilaginous when wetted; cotyledons incumbent.

Ten species: Argentina, Bolivia, Chile, Peru, and Mexico.

Key to the species of Mancoa

1. Fruits subangustiseptate-subterete, narrowly oblong to linear silique 15−17 mm long, length 5−7× width; seeds 12−24 per fruit; fruits on solitary pedicels originating from rosette center, or/and in racemes......................................................... 1. M. chontaensis

- Fruits strongly angustiseptate, elliptic, ovate, or oblong silicle 4−10 mm long, length 2−3× width; seeds 30−100 per fruit; all flowers and fruits on racemes, rarely few on solitary pedicels ..........................................................................................................2

2. Fruits densely pubescent or hispid .....................................................................................................................................................3

- Fruits glabrous....................................................................................................................................................................................5

3. Cauline leaves auriculate; sepals caducous; annuals; Mexico.................................................................................... 7. M. mexicana

- Cauline leaves not auriculate; sepals persistent; biennials or perennials; South America .................................................................4

4. Stems decumbent or prostrate, 2−8 from base; leaf trichomes 2- or 3-rayed; fruit septum complete; style 0.2−0.8 mm long; seeds 0.6−08 × 0.4−0.5 mm ......................................................................................................................................................4. M. hispida

- Stems erect, 1 or rarely 2 from base; leaf trichomes (3 or)4−8-rayed; fruit septum perforated or reduced to a rim, rarely complete; style 0.8−1.5 mm long; seeds 1−1.4 × 0.6−0.9 mm .....................................................................................................10. M. venturii

5. Racemes ebracteate (1 flower in L. perennis form last leaf axil of main stem); ovules/seeds 24−40(−50) per ovary/fruit ..............6

- Racemes bracteate at least along proximal half or third; ovules/seeds (50−)60−100 per ovary/fruit................................................7

6. Annuals; stems glabrous; leaves lyrate with 3−5 lateral lobes on each side; sepals persistent; fruits 5−7 mm long; South America. ........................................................................................................................................................................................... 5. M. laevis

- Perennials; stems pubescent; leaves dentate; sepals caducous; fruits 2−2.5 mm long; Mexico...................................8. M. perennis

7. Fruiting racemes 3−8 cm long; plants prostrate perennial; petals obsolete or to 1.2 mm long.................................9. M. rollinsiana

- Fruiting racemes> 9 cm long; plants erect, ascending, or decumbent annual or biennial; petals (1.5−) 2−4 mm long......................8

8. Fruits 3−4 mm long; fruiting pedicels 5−10 mm long ................................................................................................ 1. M. bracteata

- Fruits (5−) 6−8 mm long; fruiting pedicels 1−3(−5) mm long............................................................................................................9

9. Fruiting pedicels pubescent; petals spatulate, 3.5−4 mm long; anthers 0.6−0.8 mm long; Mexico................................... 6. M. laxa

- Fruiting pedicels glabrous; petals oblanceolate, 1.5−2.5 mm long; anthers 0.2−0.3 mm long; Bolivia........................ 3. M. foliosa

The following is the country and state or provincial distribution of all Mancoa species. For literature of their original publication, full synonymies, and typifications, the reader is advised to consult Bailey et al. (2007). Only those published post that date are listed below.

1. Mancoa bracteata (S.Watson) Rollins. Distribution: Mexico (Durango, Zacatecas).

2. Mancoa chontaensis Al-Shehbaz, Cano, Machahua, J.Roque & Mazzei. Distribution: Peru (Huancavelica).

3. Mancoa foliosa (Wedd.) O.E.Schulz. Distribution: Argentina (Jujuy, Tucumán), Bolivia (Cochabamba, La Paz).

4. Mancoa hispida Wedd. Distribution: Argentina (Catamarca, Jujuy, Salta, Tucumán), Bolivia (La Paz, Oruro, Potosí), Chile (Antofagasta, Tarapacá), Peru (Áncash, Arequipa, Cusco, Lima, Moquegua, Tacna).

5. Mancoa laevis Wedd. Distribution: Bolivia (Potosí). Peru (Puno).

6. Mancoa laxa Rollins. Distribution: Mexico (Chihuahua).

7. Mancoa mexicana Gilg & Muschl. Distribution: Mexico (Jalisco, San Luis Potosí, Zacatecas).

8. Mancoa perennis, L.Hern. & M. Martínez. Distribution: Mexico (Michoacán).

9. Mancoa rollinsiana Calderón. Distribution: Mexico (Hidalgo).

10. Mancoa venturii Al-Shehbaz. Distribution: Argentina (Jujuy), Bolivia (Cochabamba, Potosí).