Plukenetia angustifolia Standl., Publ. Field Columb. Mus., Bot. Ser.

Plukenetia angustifolia Standl., Publ. Field Columb. Mus., Bot. Ser. View in CoL , 4 (8): 314. 1929. TYPE: HONDURAS. Lancetilla Valley, near Tela, Department of Atlántida, 20–600 m, 6 December 1927 – 20 March 1928, P.C. Standley 56708 (holotype: F! [accession 581511, barcode V0057059F]; isotypes: A!, K!, US! [accession 1409360, barcode 00096449]).

Notes —See Gillespie (1993) for species discussion.

Taxonomic Discussion — Plukenetia penninervia can be divided into two informal groups united by geography and subtle differences in fruit/seed size. The first is a Mexican group that is widely distributed from southern Mexico to Panama and has average sized seeds and fruits. The second is a Venezuelan group distributed primarily in that country, which differs by having slightly larger seeds and fruits (similar to P. chocoensis ; “medium” sized seeds sensu Cardinal-McTeague et al. 2019a). The Mexican group might also more frequently lack annular nectaries in its staminate flowers, but this character needs to be investigated in greater detail. To complicate matters, there is evidence of a putative ancient hybridization event that resulted in the introgression of an ancestral plastid genome of P. chocoensis / P. loretensis into the southern population of the Mexican group, specifically within a specimen from central Panama (G. McPherson 8461) ( Cardinal-McTeague et al. 2019a, Fig. S3 View FIG ). It is unclear if the Venezuelan group (not yet sampled in phylogenetic studies) shares this same hybridization event or whether it should be considered a distinct taxon.

The two syntypes of P. penninervia correspond with these geographical groupings, A. Fendler 2412 from Venezuela and a “Herb. Pavon” collection from Mexico. Although José Pavón, of Ruiz and Pavón, most famously collected in Peru (and not Mexico), he is noted for selling duplicates of Sessé and Moci~ no’ s Mexican collections to other herbaria in Europe, where they frequently lost their association with Sessé and Mocino~ and were attributed as “Herb. Pavón, Nueva Espana~ ” ( McVaugh 2000). Indeed, there are five sheets of P. penninervia at MA (M.Sessé & J.M.Mocino~ 4212) that are physical matches with the “Herb. Pavón” sheet at G (G00418847), which we hereby consider the same collection. To maintain the taxonomic stability of P. penninervia we designate the Mexican syntype (representing the cohesive and widespread Mexican group) as the lectotype collection for the species, selecting the recently rediscovered “Herb. Pavon” G specimen (L. Gautier pers. comm.) as lectotype. Future studies will need to investigate the morphology and phylogeny of the Venezuelan group, test if it exhibits plastid genome introgression, and determine if it should be recognized as its own species or subspecies.

The P. penninervia complex, characterized by dimorphic stamens, short cylindrical styles, and 6 elliptic leaf blades, is proving to be taxonomically challenging and more speciose than previously thought. The complex is widespread from Mexico to northern South America, and comprises at least four species, P. chocoensis , P. multiglandulosa , P. penninervia , and P. supraglandulosa . Apart from our newly described Colombian species ( P. chocoensis ), several additional collections from Colombia, Ecuador, and Peru appear to belong to the P. penninervia complex and are tentatively placed in P. penninervia . Collections from northern Chocó department (Cardenas 1675, 1748, 1903) are here referred to as P. penninervia , but require further study (see the discussion of P. chocoensis for how these collections differ). Three collections from Pastaza province, Ecuador ( Gillespie 1993) and one specimen from Cajamarca province, east of the Andes in northern Peru (Vásquez 25223) have the dimorphic stamens of the P.penninervia complex, but are well south of its known range. A thorough study of the P. penninervia complex in northern South America is needed, together with additional collections, to determine if these disjunct populations represent new taxa.