(3055) Proposal to conserve the name <i>Euphorbia portulacoides</i> (<i>Euphorbiaceae</i>) with a conserved type

(3055) Euphorbia portulacoides L., Sp. Pl.: 456. 1 Mai 1753 [Angiosp.: Euphorb.], nom. cons. prop. Typus: Chile, Linares, Reserva Nacional Bellotos del Melado, 39°51′17.2″S / 71°05′32.6″W, 1370 m, 4 Jan 2000, Arroyo & al. 20100 (SGO No. 144984; isotypus: CONC), typ. cons. prop. Euphorbia portulacoides L. (Euphorbiaceae; Euphorbia sect. Nummulariopsis Boiss. in Candolle, Prodr. 15(2): 9, 71. 1862) is a species distributed in Brazil, Bolivia, Uruguay, Argentina, and Chile (POWO. 2024, available at https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:347866-1#distributions). Linnaeus's protologue of E. portulacoides (Sp. Pl.: 456. 1753) consists of a short diagnosis “EUPHORBIA dichotoma, foliis integerrimis ovalibus retusis, pedunculis axillaribus unifloris folia aequantibus, caule erecto” cited from Linnaeus & Wiman (Euphorbia: 18 (No. 25). 1752), and followed by the synonym “Tithymalus perennis, portulacae folio” cited from Feuillée (J. Obs. [2]: 707, t. 2. 1714). The provenance is reported in the protologue as “Habitat in Philadelphia. Kalm”. Regarding the works cited in the protologue, “Specimen academicum, quo Euphorbia ejusque historia naturalis et medica […] praeside […] Carolo Linnaeo […] sistit Johannes Wiman”, a dissertation of Johannes Wiman was published in 1752 by Höjer in Upsala. This work was cited extensively by Linnaeus under the Euphorbia species named in Species plantarum (1753), citing the species numbers in the dissertation (e.g., in this case “Diss. euph. 25”) rather than the page numbers (Jarvis, Order out of Chaos: 90. 2007). On the other hand, Louis Econches Feuillée (1660–1732) was a French clergyman and explorer who made many early observations in Peru and Chile, including a study of medicinal plants (l.c.: 703–767) accompanied by 50 copper plates. Most of these were cited by Linnaeus and many of them are types (see Jarvis, l.c.: 130). Linnaeus cited, although with doubt, in the protologue of Euphorbia portulacoides the illustration “t. 2?” under the polynomial “Tithymalus perennis, portulacae folio” so the illustration is an original element for this name. Among the original material used by Linnaeus to describe this species, there are three relevant specimens collected by Pehr Kalm, two preserved at LINN (mounted on the same sheet) and another at UPS. The Swedish botanist Pehr Kalm (1716–1779) was a pupil of Linnaeus and collector in North America. There he spent two-and-a-half years studying the flora and fauna of Pennsylvania, New York, New Jersey, and Quebec, Canada (Rydberg in Augustana Libr. Publ. 6: 10–13. 1907). Kalm was cited under 75 described North American species by Linnaeus in 1753 (Jarvis, l.c.: 215). These species are linked with specimens collected by Kalm preserved at LINN (by the letter “K” written by Linnaeus either near the base of the specimen or at the center, near the bottom edge of the sheet [Jarvis, l.c.]), or at UPS (Juel in Svenska Linné-Sällsk. Årsskr. 4: 20. 1921; Juel & Harshberger in Proc. Acad. Nat. Sci. Philadelphia 81: 297–303. 1929). For about 90 Linnaean binomials, Kalm's name is explicitly mentioned in the protologues (Juel in Svenska Linné-Sällsk. Årsskr. 3: 61–79. 1920; Manktelow & Nyberg in Symb. Bot. Upsal. 33(3): 73–80. 2005), usually in the form “Habitat in [geographical provenance]. Kalm”, and more than 100 Kalm specimens serve as types for Linnaean names (Juel, l.c. 1920; Jarvis, l.c.: 217). In LINN, the sheet Herb. Linnaeus No. 630.22 from the Kalm collection bears two different species of Euphorbia. This sheet is annotated, handwritten by Linnaeus, at the base: “26 / K[alm] / portulacoides”, and on the back of the sheet: “Tithymalus p[er]ennis, portulacae folio. Fewell. 707 t. 2”, the synonym cited in the protologue from Feuillée (l.c.: 707, t. 2) (images available at https://linnean-online.org/6266/). Unfortunately, neither of the two specimens mounted on sheet 630.22 (LINN) matches the current concept and use of the name E. portulacoides. The specimen mounted on the left of the sheet can be identified as E. ipecacuanhae L. (l.c. 1753: 455), and the specimen on the right as E. helioscopia L. (l.c. 1753: 459). There is another relevant specimen preserved in UPS that Kalm identified as Euphorbia portulacoides and as growing on the plains around Philadelphia (see Juel, l.c. 1921; Juel & Harshberger, l.c.). This Kalm herbarium, heavily annotated by Kalm (see Lundqvist & Moberg in Thunbergia 19: 1–62. 1993), was given to Queen Lovisa Ulrika in 1754 and kept at the Royal Palace at Drottningholm until 1803 (Jarvis, l.c.). The specimen with code 2: 160 (UPS-KALM No. V-061593 [catalogue number]) is a young and sterile plant that can be identified as E. ipecacuanhae. The sheet is annotated on the verso by Kalm: “Euphorbia dichotoma; foliis integerrimis ovalibus retusis, pedunculis axillaribus u- | nifloris folia aequantibus, caule erecto. Linn. Spec. 456: 26” and in Swedish “växer på fälten omkring Philadelphia” (grows on the fields around Philadelphia) (Lundqvist & Moberg, l.c.: 27). This material can be treated as a duplicate of the left-hand specimen of 630.22 (LINN). We have not found any specimen of E. portulacoides at BM, PH, or S-LINN, where scattered additional specimens of Kalm are preserved (see Harvard University Herbaria & Libraries, HUH Index of Botanists. 2013, https://kiki.huh.harvard.edu/databases/botanist_search.php?id=33865). Croizat (in Darwiniana 6: 183. 1943) indicated the illustration mentioned in the protologue “Tithymalus perennis, portulacae folio” and cited from Feuillée (l.c.: 707, t. 2) as type, and this “lectotypification” was supported by Jarvis (l.c.: 513). Undoubtedly, Croizat's “typification” was influenced by the correction that Sprengel (Syst. Veg. 3: 792. 1826: “Chili. (Philadelphia est sphalma)”) made of the geographical provenance indicated by Linnaeus in the protologue. However, Sprengel's correction lacks justification. Although certainly Linnaeus used mixed material for the description, there is no evidence to justify that Linnaeus was mistaken about the provenance or the collector of the original material for his E. portulacoides. Linnaeus mentioned in the protologue “Habitat in Philadelphia” and this phrase was repeated by Linnaeus in 1756 (Amoen. Acad. 3: 117) and in 1763 (Sp. Pl., ed. 2: 653). Furthermore, the name “Kalm” was included after the geographical provenance in both editions of Species plantarum (1753 and 1763). Euphorbia portulacoides is not distributed in North America, but the two species represented on Herb. Linnaeus No. 630.22 (LINN), E. ipecacuanhae and E. helioscopia, are both present there. Therefore, the origin of this material does not contradict the provenance indicated in the protologue. Curiously, following the procedure he learned from George Clifford, Linnaeus recommended in his Philosophia botanica (1751) the mounting of a single specimen per sheet of paper, and keeping these sheets separate. A possible reason why Herb. Linnaeus No. 630.22 (LINN) contains two specimens belonging to different species is that Linnaeus considered that both specimens belonged to the same species, or because one of the two specimens was added post-1753. In this sense, the lectotype of E. ipecacuanhae, designated by Reveal (in Jarvis, l.c.: 512), is a specimen collected by Kalm and preserved at LINN (Herb. Linnaeus No. 630.21; image available at https://linnean-online.org/6265/; duplicate at UPS-KALM [3: 161]), which is similar to the plant of E. ipecacuanhae preserved on Herb. Linnaeus No. 630.22 (LINN, specimen on the left) that is part of the original material for E. portulacoides. Euphorbia ipecacuanhae has alternate leaves with petiole (0–)1–2 mm, the blade usually linear, obovate, or oblanceolate to orbiculate, rarely filiform, 15–70 × 1.5–13 mm; cyathia usually in terminal dichasia, sometimes pleiochasia, whereas E. portulacoides has sessile leaves, the lower alternate, the upper opposite, the blade oblong, oblanceolate to spatulate, 10–30 × 5–15 mm; cyathia solitary or in pleiochasia. Furthermore, Linnaeus (l.c. 1756: 117) indicated for Euphorbia portulacoides “pedunculus longus, ut in praecedenti. Spec. plant.” referring (“ut in praecedenti”) to E. ipecacuanhae (i.e., “Pedunculi axillares, solitarii, uniflori, longitudine foliorum dum florent, dein fructiferi, duplo longiores”, see Linnaeus, l.c. 1756: 117). This feature is present in E. ipecacuanhae, one of the specimens mounted on Herb. Linnaeus No. 630.22 (LINN, specimen on the left) and the specimen UPS-KALM (2: 160). In conclusion, the “lectotype” designated by Croizat (s.l.) is ineffective because a gathering, with a specific locality and collector: “Habitat in Philadelphia. Kalm” (see ICN Art. 40 Note 1 and Note 2; Turland & al. in Regnum Veg. 159. 2018) is mentioned in the protologue and syntypes exist, now preserved at LINN (Herb. Linnaeus No. 630.22) and UPS-KALM (2: 160; No. V-061593). Thus, in lectotype designation Kalm's cited material in Linnaeus's protologue takes precedence over any uncited material or cited illustrations according to Art. 9.12 (see Ex. 12). Therefore, one of the specimens collected by Kalm would be the obligate choice as lectotype of the name Euphorbia portulacoides. However, unfortunately, a lectotypification of Euphorbia portulacoides using either of these specimens at LINN or UPS-KALM in accordance with Art. 9.12 would be nomenclaturally disruptive since neither of them matches the current concept of the name. Accordingly, for the purpose of nomenclatural stability and to support the continued and well-established use of the name E. portulacoides, we propose to conserve the name with a conserved type under Art. 14.9. We here propose a well-preserved and complete specimen (Arroyo & al. 20100) at SGO (No. 144984) as the conserved type of Euphorbia portulacoides. This material is a modern specimen, collected in Chile, with a duplicate preserved at CONC. This material was cited by Arroyo & al. (in Gayana, Bot. 57: 130. 2000) and shows diagnostic characters of this species (e.g., dichotomously branched stems ending in 2- or 3-ray umbels; sessile leaves, the lower alternate and lanceolate or elliptical-lanceolate to obovate with acute apex, the upper ones opposite, oval or oblong; cyathial features with campanulate involucre and thick, broadly reniform, dark red glands), and clearly represents the current application of the name. Rejection of the present proposal would have very undesirable consequences, because Euphorbia portulacoides would become a heterotypic synonym of either E. ipecacuanhae or E. helioscopia, depending on the selection of a lectotype from the specimens at LINN or UPS-KALM, and the name E. chilensis Gay (Fl. Chil. 5: 335. 1851) would replace what until today is commonly known as E. portulacoides. For example, Google Scholar searches (on 17 Sep 2024) on usage of the two names over the last 150 years yielded 210 results for the latter and only 18 for the former. We thank the staff of the cited herbaria, Mats Hjertson (UPS), Gloria Rojas (SGO), Jimena Ponce and Rocio Deanna (CORD), and Patricia Hernández Ledesma (IEB), for the valuable help in the study of the herbarium sheets. Thanks to Dr. John Wiersema for his valuable advice and for reviewing the manuscript and making improvements.

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