Pimenta yumana (Alain) T. Vasc., 2018

Vasconcelos, Thais N. C., Lucas, Eve J. & Peguero, Brigido, 2018, One new species, two new combinations and taxonomic notes on the All-spice genus Pimenta (Myrtaceae) from Hispaniola, Phytotaxa 348 (1), pp. 32-40 : 37

3. Pimenta yumana (Alain) T. Vasc. , comb. nov.

Basionym:— Eugenia yumana Alain, Phytologia 25: 268 (1973).

Eugenia yumana and Eugenia samanensis both present tetramerous flowers, inflorescences reduced to solitary flowers and two locules in each ovary. Both Eugenia and Pimenta can display such traits, which may explain the confusion. The combination of these traits with strongly aromatic leaves, coiled or c-shaped embryos, a single series of ovules around a protruded placenta and occasional dichasial inflorescences (observed in Eugenia samanensis ), however, is unique to Pimenta and supports moving these species into the latter genus. Eugenia yumana is confirmed to be placed in Pimenta by molecular analysis with high bootstrap (>70%) and posterior probabilities (>0.95) (see Figure 1B and Vasconcelos et al., 2017) and the collection used in that study comes from the type location of that species, in boca de Yuma, sea level (voucher T. Vasconcelos 584).

Eugenia yumana and Eugenia samanensis are morphologically very similar and likely closely related or even the same taxon (see Liogier, 1986), but the distinct distribution within the Dominican Republic (see Figure 1A , yellow triangle and star respectively) and subtle differences in inflorescence axis length (ca. 0.5 cm long in Eugenia yumana and ca. 1.5 cm long in E. samanensis ) led us to follow a conservative approach and move them into Pimenta separately. Liogier (1973) emphasizes the slight resemblance of this species to others in the same genus when describing Eugenia yumana : “this plant has little resemblance to any other species of Eugenia in the West indies; its subsessile inflorescence, its ellipitic coriaceous leaves, with numerous nearly parallel nerves are the most outstanting characteristics” (1973: 269). Eugenia yumana and E. samanensis are also very distinct from other Hispaniola Pimenta species, especially regarding their reproductive features: both species are tetramerous, whilst all others ( Pimenta berciliae , Pimenta haitiensis , and all endemic varieties of Pimenta racemosa ) are pentamerous, and its inflorescences are almost sessile with few flowers, whilst all others present longer dichasia or panicles. Leaves of Eugenia yumana and E. samanensis are similar to Pimenta ferruginea (from Cuba), but the latter always presents dichasial inflorescences and longer pedicels (up to 4 cm) in comparison to almost subsessile inflorescences in the former two.

Figures

FIGURE 1. Distribution and phylogenetic position of treated species within Pimenta. (A) Natural distributions of Pimenta berciliae (red circles); P. yumana (yellow triangle) and P. samanensis (yellow star). (B) An extract from the Myrteae phylogeny (see Vasconcelos et al., 2017 for methodology) based on maximum likelihood analysis of two markers (ITS and psbA-trnH; see Appendix 1 for Genbank accession codes) showing phylogenetic positions of Pimenta berciliae and Pimenta yumana. Bootstrap values above 90 are given at each node.