Hymenoxys megapotamica (Spreng.) P.L.R.Moraes, 2020

Moraes, Pedro Luís Rodrigues De, 2020, The taxonomic identity of two neglected Sprengel names, Galinsoga megapotamica and G. uniflora (Asteraceae), with remarks upon Friedrich Sellow’s collections galore, Phytotaxa 438 (3), pp. 163-181 : 165-166

Hymenoxys megapotamica (Spreng.) P.L.R.Moraes , comb. nov.

Basionym:— Galinsoga megapotamica Sprengel (1826: 580) . Protolog:—COUNTRY NOT INDICATED. “ Ad fl. magnum Amer. austr. ( Rio grande .) Sello”. Type:—COUNTRY NOT INDICATED. Loco haud indicato, s.d., F. Sellow s.n. (Lectotype designated here: P! barcode P02509834, ex Herb. Sprengel 1557). Possible isolectotype:— URUGUAY. [inter Mercedes et Salto], January–February 1823, F. Sellow d 901 [Herbier Impérial du BRÉSIL N. o 1078] (P! barcode P02509867).

Synonym:— Hymenoxys tweediei Hooker & Arnott (1841: 323) , as “ Tweedei ”, syn. nov. ≡ Actinea tweediei (Hook. & Arn.) Kuntze (1898: 128) , as “ Tweedii ” ≡ Actinella tweediei (Hook. & Arn.) Malme (1931: 73) . Type:—[protolog] “ Rio Grande , and dry pastures, road sides of Los Loamos, N. Patagonia; Tweedie, (n. 859)”, lectotype designated here:— ARGENTINA. “Dry pasture grounds, sides of Los Loamos [of Bahia Blanca], N. Patagonia”, s.d., J. Tweedie 859 (K barcode K000504096, two specimens mounted on same sheet; left-hand specimen; isolectotype: E barcode E00322626). Other syntype:— BRAZIL. “ Rio Grande ”, loco haud indicato, s.d., J. Tweedie s.n. (E barcode E00322625, K barcode K000504096, right-hand specimen). Possible syntype:— BRAZIL. “W of Rio Grande ”, loco haud indicato, 1837, J. Tweedie s.n. (K barcode K001107825).

Stafleu & Cowan (1985) pointed out that Kurt Sprengel’s herbarium, after the death of his son Anton in 1851, was sold in parts, with a certain number of families and genera going to specialists. The specimens of Asteraceae were acquired by Schultz-Bipontinus (Carl Heinrich Schultz) and are currently at P through the herbarium of E. Cosson. Specimen P02509834 has the original label of Sprengel annotated with “Galinsogea / Gutierrezia megapotamica * / Sello”, and therefore must be taken as original material of Galinsoga megapotamica , thus making it eligible as the lectotype of the name (for examples of original labels by Sprengel, see Moraes et al. 2016). Sprengel’s specimens of the Asteraceae ex Herbarium Schultz-Bipontinus in Herbarium E. Cosson at P have been taken as the holotypes of names by several authors. Actually, this practice is not strictly correct under Art. 9.1 of the ICN (Turland et al. 2018), since Sprengel usually did not indicate nomenclatural types, Sellow’s specimens of his herbarium were acquired from B, where at least one duplicate of them once existed (see Schultz 1863), and because Sprengel may have seen and/or used more than a single Sellow specimen at B.

Specimen P02509834 was annotated by Kittie F. Parker as “ Hymenoxys tweediei H. & A.” in 1960, and cited in her publication ( Parker 1962) as: ‘Country unknown. Brazil or Uruguay, Sello (P). This may be Sello 901, which Baker (1884) cited as “Habitat in Brasilia australi: Sello 901!;” and Malme (1931), as “Specimina Sellowiana (n. d. 901) in Uruguay...”’. Nevertheless, she did not say anything about it being original material of Sprengel’s Herbarium. Actually, Baker (1884: 278), in Martius’s Flora Brasiliensis , stated “ Habitat in Brasilia australi: Sello n. 901!; ad oram fluminis Rio Grande : Tweedie! ” as the specimens examined for Hymenoxys tweediei , and Malme (1931: 73) cited “ Rio Grande do Sul, loco non indicato (Tweedie). Specimina Sellowiana (n. d. 901) in Uruguay lecta sunt” under Actinella tweediei . The facts that the latter two authors had cited only Sellow d 901 among his collections at B, were the very authors that had seen the specimens at B prior to 1943, and quoted Sellow’s collecting numbers, are evidence that the material would be the same Sellow collection from which Sprengel got a sample for his herbarium. In general, Sellow made several to many duplicates of each collection and, sometimes, the same species was collected in different places, thus receiving different collecting numbers. However, in this case, it seems that the species was just collected once, since no other Sellow collection has been cited and/or located so far. A duplicate of Sellow d 901, with an original label tied to the specimen, is currently at P through the “Herbier Impérial du Brésil ” (P02509867). This specimen perfectly matches the lectotype of G. megapotamica .

In the protolog of Hymenoxys tweediei, Hooker & Arnott (1841) cited two specimens collected by James Tweedie, one from “ Rio Grande ” (Brazilian state of Rio Grande do Sul), and the other from the Argentinean Patagonia, thus being syntypes (Art. 9.6 of the ICN; Turland et al. 2018). Since Parker (1962) only indicated “ holotype, K”, it would be inappropriate for this to be corrected to lectotype (Art. 9.10 of the ICN; Turland et al. 2018), since the original material of H. tweediei comprises two syntypes. However, at K herbarium, currently, these two syntypes, from different collections, are mounted on the same sheet (K000504096). Parker (1962) did not distinguish between the two specimens that are associated with the name, and as they are evidently not part of a single gathering, Art. 9.17 of the ICN (Turland et al. 2018) does not apply. Although Carneiro & Ritter (2016) had distinguished the two syntypes by quoting “ Brazil, Rio Grande , and dry pastures, p.p.; Argentina, Patagonia, roadsides of Los Loamos, p.p., s.d., Tweedie 859 (Holótipo: K, foto!)” they neither designated a lectotype according to Art. 7.11 and Art. 9.23 of the ICN (Turland et al. 2018), nor presented any commentary on typification. Therefore, Tweedie’s specimen from Patagonia is here selected as the lectotype since it is the best one, bearing eight capitula, whereas the specimen collected in Rio Grande do Sul bears only one capitulum.