Oxybasis macrosperma subsp. salsa (Phil.) Uotila, 2022

Uotila, Pertti, 2022, New combinations and notes on Oxybasis (Amaranthaceae) from southern South America, Candollea 77 (1), pp. 9-16 : 12-13

Oxybasis macrosperma subsp. salsa (Phil.) Uotila , comb. nov.

 Blitum salsum Phil. in Anales Univ. Chile 91: 423. 1895.  Chenopodium macrospermum subsp. salsum (Phil.) A. Tronc. in Not. Mens. Mus. Nac. Hist. Nat. 18(211): 6. 1974.

Lectotypus (designated by TRONCOSO, 1974: 7): CHILE. Reg. O’Higgins: Cardenal Caro, Bucalemu, I.1878, Sanfurgo s.n. ( SGO [ SGO000001626 ] image!; isolecto-: G [ G00398323 fragm.]!, SGO [ SGO000001625 ] image!, US).

= Chenopodium macrospermum f. nanum Aellen in Repert. Spec. Nov. Regni Veget. 26: 44. 1929. Lectotypus (designated here): BOLIVIA. Dept. La Paz : Guaqui , Ufer des Titicaca Sees, 3820 m, III.1910, Buchtien 2828 (US [ US00169597 ] image!; isolecto-: G [ G00426956 fragm.]!, US [ US007229802 ] image!).

Distribution and ecology. – This subspecies is widely distributed in the Cono Sur: Argentina (provinces of Buenos Aires, Catamarca, Chubut, Río Negro, Mendoza, Santa Cruz, Santa Fe, San Juan), Chile (regions of Antofagasta, O’Higgins, Maule, Metropolitan), Uruguay (departments of Canelones, Montevideo, San José), and Paraguay (department of Presidente Hayes). It also occurs in the Bolivian departments of Cochabamba and La Paz. It grows in many types of open habitats, often in marshy lakeshores, showing preference for sand and saline soils ( NAVAS BUSTAMANTE, 1976).

Oxybasis macrosperma subsp. salsa has been recorded as introduced in USA, Mexico, Europe ( AELLEN, 1960) and Australia ( WILSON, 1984) under the names Chenopodium macrospermum or C. macrospermum subsp. halophilum . European plants have remained casual, many of them non-flowering or at least non-fruiting, which may indicate their origin from shorter-day conditions.

Notes. – Oxybasis macrosperma is morphologically variable regarding the habit, leaf size and shape, inflorescence, density of vesicular trichomes (especially on the lower leaf surface) and seed size. AELLEN (1929) recognized Chenopodium macrospermum subsp. macrospermum (under the name C. subsp. crassicaule (Moq.) Aellen ), which is limited to the Falkland Islands and southernmost part of the continent, and the more widespread C. macrospermum subsp. halophilum (currently Oxybasis macrosperma subsp. salsa ; see above under Oxybasis halophila ). This division was generally accepted in South America until 2012.

In the recent treatments of the genus no subspecies are accepted ( FUENTES-BAZAN et al., 2012; MÚLGURA & GALARZA, 2014; BRIGNONE, 2020). However, differences in leaf and inflorescence characters and seed size ( Table 1), besides the more or less allopatric areas justify recognition of the two subspecies. Small plants of subsp. salsa may have a habit resembling that of subsp. macrosperma , but they differ at least in having smaller seeds (1 mm). The description of Oxybasis macrosperma given by BRIGNONE (2020) fits well with the subsp. salsa but practically excludes subsp. macrosperma .

The isolectotype of Blitum salsum at B was destroyed during the Second World War except for a small fragment taken by Aellen for his herbarium. The specimen of US was cited as “Orig. von Blitum salsum Phil. (Herb. Wash.) ” by AELLEN (1929), however, it has not been located.

Chenopodium macrospermum f. nanum Aellen was described on the basis of the collection Buchtien 2828 ( US), which consists of two specimens. Because US 00169597 is more complete, it is designated here as the lectotype. There is also a fragment in G origitating from Aellen herbarium. The plants are less than 5 cm tall, have small (1 cm long), entire, succulent leaves and fairly compact inflorescences; however, their seeds do not exceed 1 mm in diameter.

Additional specimens examined. – ARGENTINA. Prov. Chubut: Rawson , 0.5 km N of Trelew, 30 m, 23.XII.1938, Eyerdam et al. 23756 ( G, K) . Prov. Mendoza: San Rafael, IV.192?, Parodi 8543 ( G) . Prov. Río Negro: Vicinity of General Roca , 250–360 m, IX.1914 – II.1915, Fischer s.n. ( BM) . Prov. Santa Cruz: Lago San Martín , Península Maipu, 3.III.1903, Hogberg 33 ( BM) .

BOLIVIA. Dept. La Paz: Murillo, Mecapaca, c. 20 km al SE de La Paz ( La Florida ), 16°38' S 68°03'W, 2950 m, 14.II.1987, Solomon & Nee 16083 ( G) .

CHILE. Reg. Metropolitana: Santiago, Lake Aculeo , c. 500 m, V.1971 , Troncoso s.n. ( G).

PARAGUAY. Dept. Presidente Hayes: Estancia Tinfunque, a 5 km al oeste de Tinfunké, 100–150 m, 23.IX.1987, Spichiger et al. RS2143 ( G); Pilcomayo River , 1888–1890, Morong 918 ( BM, G, K) .

URUGUAY. Dept. San José: Barra Sta. Lucía, 11.III.1921, Osten 22183 ( S) . Dept. Montevideo: 15. VI .1932, Fruchard s.n. ( P) .