Plukenetia volubilis, L.

Cardinal-McTeague, Warren M. & Gillespie, Lynn J., 2020, A Revised Sectional Classification of Plukenetia L. (Euphorbiaceae, Acalyphoideae) with Four New Species from South America, Systematic Botany (Basel, Switzerland) 45 (3), pp. 507-536 : 533

25. PLUKENETIA vOLUBILIS L., Sp. Pl. 1 (2): 1192. 1753.

Sajorium volubile (L.) Baill., Étude Euphorb. 483. 1858.

TYPE: WEST INDIES. Illustration t.13 (lower half) in Plumier, Nov. Pl. Amer. 1703 (lectotype designated by Howard 1989) .

Plukenetia peruviana Müll.Arg., Linnaea 34: 157. 1865. TYPE: PERU. Peruvia, Herb. Pavon [likely H. Ruiz & J. Pavón s.n.] (lectotype designated here: G! [barcode G00418846]; isolectotype: G-DC! [barcode G00313656; photo at F!]).

Plukenetia macrostyla Ule, Verh. Bot. Vereins Prov. Brandenburg 50: 80. 1908. TYPE: BRAZIL. Amazonas : Rio Juruá sup., September 1901, E. Ule 5864 (holotype: B [destroyed]; lectotype designated here: G! [barcode G00441991; photo at F!]; isolectotypes: F! [fragment], HBG [barcode HBG-515849; image!], MG [barcode MG005766;image!]).

? Fragariopsis paxii Pittier, J. Wash. Acad. Sci. 19: 351. 1929. TYPE: VENEZUELA. Aragua: Hacienda Puerto La Cruz, Coastal Range, 1000 m, 28 August–4 September 1918, H. Pittier 8109 (holotype: VEN [accession 6906, barcode VEN 6906; image!]; isotype: GH! [barcode 00048014], US! [accession 988210, barcode 00096452]). [appears to be intermediate between P. stipellata and P. volubilis ; see discussion of Gillespie 1993 for more detail]

Notes —See Gillespie (1993) for species discussion and Gillespie and Armbruster (1997) for species description.

Taxonomic Discussion —The P. volubilis species complex includes a main group of typical lowland moist to wet forest P. volubilis , plus two smaller groups that differ in morphology and phylogeny and may warrant their own taxonomic rank. The first is an open savanna species group found on the Moxos Plains of Bolivia. This group has broad leaf blades with subcordate bases similar to the typical moist or wet forest P. volubilis , but differs in its habitat, generally thicker leaf blades, and smaller seeds/fruit (“medium” compared to “large” sensu Cardinal-McTeague et al. 2019a). Accessions of the open savanna group (known only from Nee 55162 MO and Parada et al. 206 CAN, MO) form a strongly supported clade sister to the remaining moist to wet forest P. volubilis ( Cardinal-McTeague et al. 2019a), suggesting this group could represent a distinct taxon on the basis of ecology and phylogeny. Floral morphology of the open savanna group is not yet known and additional collections are needed to verify if there are sufficient characters to warrant a new species.

The second is a mid-elevation species group from the Andes of Bolivia and Peru. Individuals in this group are found at higher elevations, (200)500–900(1800) m, than the typical moist to wet forest species group (usually to 500 m). The mid-elevation group is known from many collections across Bolivia ( Jaramillo et al. 1237 MO [208 m]; Teran et al. 2006 MO [800 m]; Teran et al. 2502 MO [1800 m]) and Peru (Foster & Wachter 7404 MO [500–600 m]; Gentry et al. 40071 MO [830–900 m]; Huamán. 188 MO [290 m]; Huamantupa et al. 3500 MO [780 m]; Nù~ nez 13775 MO [640 m]; Rojas et al. 4349 MO [800 m], 4593 MO [800 m], 5222 MO [600 m], 5525 MO [1500 m], 5665 MO [600 m], 8491 MO [500 m]; Rojas & Ortiz 6726 MO [500 m]; Valenzuela et al. 8531 MO [739 m], 9242 MO [1200 m], 10968 MO [1000 m], 12029 MO [375–635 m]; van der Werff et al. 18445 MO [700 m]). These collections are differentiated by their narrower leaf blades and cuneate or truncate bases, compared to broader leaf blades with subcordate or cordate bases in typical P. volubilis . Other characters such as style length and fruit/ seed size share the same breadth of variation observed in the typical P. volubilis group. Phylogenetic analyses suggest mid-elevation accessions (Huamantupa et al. 3500, Jaramillo et al. 1237, Teran et al. 2502, Valenzuela et al. 8531) form a strongly supported clade embedded within typical P. volubilis ( Cardinal-McTeague et al. 2019a). Although the mid-elevation group appears to form a cohesive lineage within P. volubilis , it exhibits considerable geographical overlap and gradation of leaf shape characters with the typical lowland moist and wet forest group, and might be better recognized as an ecological variant without taxonomic status.

Further work is needed to clarify species group boundaries in the P. volubilis complex. Future studies should test the resolution of our proposed groups with improved taxon sampling across the geographic range of P. volubilis , specifically from the central and eastern Amazon basin, the Guianas, and the Lesser Antilles. Additionally, the putative hybrid population in Venezuela, intermediate between P. stipellata and P. volubilis (associated with the tentative synonym? Fragariopsis paxii ; see Gillespie 1993), requires further investigation.

Here we designate lectotypes for two of the synonyms of P. volubilis . The protologue of P. peruviana listed two specimens as syntypes, “In Peruvia (hb. Pavon!)” and “in prov. Maynas (Poeppig n.2110!)”. We have not yet observed E.F. Poeppig 2110 and at the time of writing the G herbarium could not locate such a specimen (L. Gautier pers. comm.), which precludes its evaluation. Of the Pavon sheets, we select the G00418846 specimen as lectotype since it has abundant floral material as well as a developing fruit. The presumed holotype of P. macrostyla was destroyed in Berlin. Although each of its isotypes are in good condition and demonstrate pistillate flower morphology, we designate the G00441991 specimen as lectotype since it also contains staminate buds near anthesis.