Chenopodium parodii, Aellen, 1929

Mosyakin, Sergei L. & De Lange, Peter J., 2018, New combinations for three taxa of the Oxybasis glauca aggregate (Chenopodiaceae) from Australasia, East Asia, and South America, Phytotaxa 350 (3), pp. 259-273 : 264-265

Chenopodium parodii from South America ( Argentina)

Aellen (1929: 49) described Chenopodium parodii from Santa Cruz Province ( Argentina), and distinguished it from other taxa of the C. glaucum aggregate mainly by its slightly to prominently trilobate leaf blades, almost as long as broad, irregularly erose-sinuate to dentate at margins, and especially by unusually long petioles (normally longer than leaf blades). Further studies (Aellen 1960–1961, Planchuelo 1975) revealed some additional diagnostic characters of flowers and fruits. Flowers in C. parodii are arranged in short axillary glomerules; membranous tepals (usually 5– 3 in terminal flowers, 2–4 in lateral ones) are normally rather narrow, lanceolate or slightly spathulate to almost linear, free almost to the base, shorter than the fruit and often with purple apex, glabrous or nearly so, and not keeled. Seeds are mostly vertical, less commonly horizontal, normally (0.7–) 0.8–0.9 mm in diameter, with granular and reddish-brown testa. The combination of morphological characters of that taxon is rather peculiar and does not occur in other taxa and morphotypes of the Oxybasis glauca aggregate in other regions of the world. In 1943 Aellen submerged this taxon in Chenopodium glaucum as a subspecies ( Aellen & Just 1943) but later decided to treat it again as a distinct species (Aellen 1960–1961).

Chenopodium parodii is considered an endemic species restricted to Argentinean provinces Chubut, Mendoza, Neuquén, Río Negro, and Santa Cruz, and it is recognized in that rank in all major floristic publications of the region ( Planchuelo 1975, Giusti 1984, 1997, Múlgura 1999, Múlgura & Marticorena 2008, Múlgura de Romero 2008 –onward; see also the continuously updated online databases available through the Instituto de Botánica Darwinion: http:// www.darwin.edu.ar/Proyectos/FloraArgentina/fa.htm; Zuloaga & Belgrano 2015). The species is also included in the provisional Red List of endemic plants of Argentina ( Lista Roja Preliminar de las Plantas Endémicas de la Argentina: see Secretaria de Ambiente y Desarrollo Sustentable 2010, Múlgura de Romero 2008 –onward).

Another taxon belonging to Oxybasis in its current circumscription was described from Argentina as a variety by Spegazzini, and later it was listed as a synonym of C. parodii by Aellen (1960–1961); thus, a taxonomic and nomenclatural clarification was needed and is provided below.

Spegazzini listed under Blitum rubrum (L.) Reichenbach (1832: 582) (≡ Chenopodium rubrum , now accepted as Oxybasis rubra ) the following three varieties: a) macrospermum (Hook. f.) Speg. (as “ macrosperma ”; corresponding to Oxybasis macrosperma ), b) “ vulgare Moq.” [nom. inval. (Art. 24.3 of the ICN), corresponding to O. rubra s. str.], and c) “ hypoleuca Speg.” (correctable to hypoleucum following Art. 23.5 and 32.2 of the ICN; McNeill et al. 2012). He provided the following original description of the latter variety: “erecta v. prostrata , viridis v. rubra , foliis subtus semper dense albo-papulosis, margine acute denticulatis, seminibus lenticularibus (0,75– 1 mm diam.) tenuiter reticulatis” ( Spegazzini 1902a: 287, 1902b: 141; text identical in both publications).

We found online digital images of three original specimens of B. rubrum var. hypoleucum annotated by Spegazzini; one specimen (LP003125) was supposedly collected by Spegazzini himself (however, no collector’s name is indicated on the original label) and two other specimens (LP003126 and LP003127) were collected by Carlos Ameghino. All three specimens are considered syntypes in the JSTOR Global Plants database (see links below). In fact, no syntypes were indicated by Spegazzini for his var. hypoleucum ; he simply mentioned in the protologue that the species Blitum rubrum is common in wet saline habitats in all parts of Patagonia [“Vulgatum in uliginosis salsis per totam Patagoniam, per ann. 1882–900”; Spegazzini (1902a: 286, 1902b: 141)], without any further information on distribution or studied specimens of the three varieties. However, the years 1882–1900 mentioned by Spegazzini indicate that only plants collected during this period should be considered original specimens of var. hypoleucum . When describing new taxa from Patagonia, Spegazzini (l.c.) widely used specimens collected and provided by C. Ameghino (see Spegazzini 1902a, 1902b, Katinas et al. 2000), so the specimens LP003126 and LP003127 also belong to original material.

The label data of all three original specimens are provided below, with our technical comments in square brackets and lines of original labels separated by the vertical bar. Here and below, herbarium acronyms are given following Index Herbariorum ( Thiers 2018 –onward):

1) LP003125 (two erect plants). Label 1: “ Blitum rubrum (L.) Reich. | var. hypoleuca Speg. ” [final identification written in ink over earlier provisional identifications]; “ Chenopodium | ( Blitum ) | ( Agathophyton ) | elegans Speg. (n. spec.) [crossed out] | hircinum Schrad. DC. Pr. XIII-II/66 | Hab. Chubut ” [text in pencil: earlier identification and locality]; Label 2 (curatorial, printed and typewritten): “Herbario Museo de La Plata (LP), etc.” [printed text]; “ Blitum rubrum var. hypoleuca Speg. | ‘CHUBUT’ | Ex herbario Instituto C. Spegazzini (LPS), en LP | Leg. C. Spegazzini” [typewritten text] (digital image available from: https://plants.jstor.org/stable/10.5555/al.ap.specimen.lp003125);

2) LP003126 (one prostrate plant, much-branched at base). Label 1: “ Blitum rubrum (L.) Reich. | var. hypoleuca Speg. | Cerro Kman-aik (R. Chico) | Patagonia | 2/1898 C. Ameghino” [words “Patagonia” and “C. Ameghino”—blue-ink stamp]; Label 2 (curatorial): “Universidad Nacional de La Plata | Museo—Instituto Spegazzini | Herbario | No. 12067” [printed, with a typewritten number added] (digital image available from: https://plants.jstor.org/stable/10.5555/ al.ap.specimen.lp003126);

3) LP003127 (two fragments of prostrate or somewhat ascending plants). Label 1: “Col-huapi Chubut | Aut. 1900 | C. Ameghino” [blue-ink stamp]; Label 2 (handwritten, manu Spegazzini?): “ Blitum rubrum (L.) Reich. | var. hypoleuca Speg. | Hab. in subsalsis uliginosis prope Coluhuapi, aut. 1900 | (C.A.)”. Label 3 (curatorial): “Universidad Nacional de La Plata | Museo—Instituto Spegazzini | Herbario | No. 12066” [printed, with a typewritten number added] (digital image available from: https://plants.jstor.org/stable/10.5555/al.ap.specimen.lp003127).

The specimen LP003125 contains two erect plants with deltoid leaves much dentate at margins. In the opinion of the first author (Sergei Mosyakin), these plants belong to Oxybasis macrosperma [the infraspecific taxon corresponding to Chenopodium macrospermum subsp. halophilum ( Philippi 1861: 67) Aellen (1929: 42) f. farinosum (S. Watson) Aellen (1929: 43) ≡ C. murale L. var. farinosum S. Watson (1874: 97) ≡ C. farinosum (S. Watson) Standley (1916: 28) ≡ C. macrospermum var. farinosum (S. Watson) J.T. Howell (1948: 105) ; see Aellen: 1929: 42–43]. Probably because of that Aellen (1929: 43; Aellen & Just 1943: 58) listed Blitum rubrum var. “ hypoleuca ” in synonymy of C. macrospermum subsp. halophilum f. farinosum . Two other original specimens (LP003126 and LP003127) evidently belong to Oxybasis parodii .

It looks like C. macrospermum var. hypoleucum has not been yet properly lectotypified. When selecting a lectotype, we should consider that the characters reported in the protologue (plants erect or prostrate, green or reddish, with leaves acutely denticulate at margins and mealy beneath, and seeds 0.75–1 mm in diameter) more or less closely match the characters of both O. macrosperma (in particular, its infraspecific entity Chenopodium macrospermum subsp. halophilum , which has not yet been formally transferred to Oxybasis ) and O. parodii . We should also note that Aellen (1929) initially synonymized Blitum rubrum var. hypoleucum with Chenopodium macrospermum subsp. halophilum , so it seems to be proper to follow his earlier opinion and to select the specimen LP003125 as a lectotype. However, judging from the list of studied specimens, Aellen in 1929 was not familiar with any specimens from Argentina collected by Spegazzini or Ameghino, so his synonymization was based mainly or exclusively on the available descriptions. Later he rather confusingly cited Chenopodium rubrum var. “ hypoleuca Speg.” [in fact, that combination was validated by Hauman & Irigoyen (1923: 88)] in synonymy of C. parodii and, on the same page, mentioned Blitum rubrum var. “ hypoleuca Speg.” in synonymy of C. macrospermum subsp. halophilum (Aellen 1960–1961: 613). By those not quite accurate citations he most probably acknowledged (evidently based on additional specimens seen) that Spegazzini’s concept of var. hypoleucum in fact covered two rather distinct taxa. It should be also taken into account that the specimen LP003125 contains confusing identifications, with no collector’s name indicated (judging from the locality, Chubut, its collector could be either Spegazzini or Ameghino). Based on all considerations mentioned above, we decided to follow the later updated taxonomic concept of Aellen (1960–1961) and to designate the specimen LP003127 as the lectotype of B. rubrum var. hypoleucum , thus making the name a synonym of Oxybasis parodii .