Plukenetia sect. Fragariopsis (A.St.-Hil.) Card.-McTeag. & L.J.Gillespie

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 : 516

II. Plukenetia sect. Fragariopsis (A.St.-Hil.) Card.-McTeag. & L.J.Gillespie , comb. et stat. nov.

Fragariopsis A.St.-Hil., Leçons Bot. 426. 1840.

TYPE: Fragariopsis scandens A.St.-Hil. [= Plukenetia serrata (Vell.) L.J.Gillespie ]

Lianas, stems slender to thick. Leaf venation pinnate, primary vein 1. Inflorescences bisexual racemose thyrses; pistillate flowers solitary at 1–10 basal-most nodes; staminate flowers 2(3)/ node in condensed cymules. Staminate flowers: receptacle globose; nectaries absent; stamens 10(–20), loosely packed (receptacle clearly visible between anthers); filaments absent; pollen P = 32–46 m m, E = 42 –55 m m, tectum coarsely reticulate. Pistillate flowers: styles entirely connate into an obovoid column, 3–3.5 mm long. Fruits 4–lobed or subglobose-quadrangular, capsule-like, initially fleshy, apparently indehiscent or tardily splitting, 4–5 cm in diam. Seeds subglobose, 15–15.5 ˟ 15.5–16 ˟ 15–16 mm (“large” sensu Cardinal-McTeague et al. 2019a).

The single species in this section is distributed in the Atlantic Forest of Brazil.

Etymology —The sectional epithet is derived from Fragaria (Latin, strawberry) and - opsis (Greek, appearing like or resembling), referring to the androecium, which has the appearance of a small strawberry. We chose the name Fragariopsis because it describes the androecium morphology that is unique to the section and because historically it was the more widely known genus that contained Plukenetia serrata .

Discussion —Section Fragariopsis refers to subclade P1 ( Fig. 1 ) and includes a single species, P. serrata , from the Atlantic Forest region of Brazil. This species/section has long been recognized as a distinct genus ( Table 1 ), but belongs within Plukenetia due to their numerous shared characters ( Gillespie 1993) and phylogenetic relationships ( Cardinal-McTeague and Gillespie 2016; Cardinal-McTeague et al. 2019a). Together, sects. Fragariopsis and Penninerviae constitute the pinnately veined clade (P1 + P2), which is united by pinnate leaf venation, coarsely reticulate pollen tecta, all or mostly sessile anthers, and entirely connate styles. Section Fragariopsis is differentiated by its unique androecium composed of sessile anthers loosely packed on a globose receptacle ( Fig. 2B ), as well as by having 1–10 pistillate flowers, “large” seeds derived from fleshy fruits, and for being the only section distributed in the Atlantic Forest region of Brazil.

Figures

FIG.1. Summary cladogram of the relationships recovered by Bayesian analysis of combined and partitioned ETS,ITS, KEA1 introns 11 and 17, TEB exon 17, matK, and ndhF DNA sequence data of Plukenetia and Romanoa (modified from Cardinal-McTeague et al. 2019a), highlighting our revised sectional classification of Plukenetia. Maximum parsimony bootstrap percentage (MPBP) and Bayesian posterior probability (BPP) support values> 50% are indicated on each branch. Branches in bold indicate strong support ($ 85 MPBP and $ 0.95 BPP). Subclade numbering system (P1–P5) follows Cardinal-McTeague and Gillespie (2016). Sections in the pinnately veined clade (P1 + P2) are indicated by light grey boxes,sections in the palmately veined clade (P3–P5) by dark grey boxes; new species are indicated in bold. A–B. Leaf clearings demonstrating leaf architecture (images from Gillespie 1993). A. P. stipellata, Gillespie 413 US. B.P. supraglandulosa, Granville 3626 CAY.C–D. Scanning electron micrographs demonstrating pollen tectum morphology (images from Gillespie 1994). C. P. stipellata, Gillespie 418 DAV. D. P. loretensis, Maguire & Politi 27371 US.

FIG. 2. Representative staminate flower diversity of Plukenetia and its sister genus Romanoa. A. Romanoa tamnoides (Krapovickas & Schinini 36265 MO), stamens with slender-cylindrical filaments.B.P.sect.Fragariopsis:P.serrata(Davidse etal.10480 MO),anthers sessileand looselypackedon alarge globosereceptacle.C–E.P.sect.Penninerviae: C.P.loretensis (Freitas et al.155 MO),anthers sessile and densely packed on a small globose receptacle;D.P.penninervia (vander Werff et al.3173 MO),and E.P.supraglandulosa (Granville 3626CAY,US),mostanthers sessile and densely packedon a smallglobose receptacle,witha dimorphicouter whorl of;4 stamenswith filaments,and often witha 4-lobed annular nectary. F–I. P. sect.Plukenetia: F. P. polyadenia (Croat et al.20285 MO), stamens with slender-cylindrical filaments and ligulate interstaminal nectaries; G. P. stipellata (Cardinal-McTeague 8 CAN),stamens withslender-cylindrical filaments and small irregularlyshaped interstaminal nectary segments;H.P.sylvestris (Woytkowski 6670 MO), stamens with slender filaments and large irregularly shaped interstaminal nectary segments;I. P. volubilis (Wurdack s.n.US), stamens with short-conical filaments.J.P. sect.Angostylidium: P.conophora (Avio et al.1621 MO), stamens with short-conical filaments and slender-cylindrical interstaminal nectaries (in pink). K. P.sect.Hedraiostylus: P.corniculata(ChinSee Chung 2712L),stamenswith short-conicalfilaments (sometimes appearingsessile).L.P.sect.Madagascarienses:P.madagascariensis(Villiers et al.4889 MO), anthers more or less sessile,denselyto somewhatloosely packedon an elongatereceptacle.PhotosA–D,F–H,J,Lby W.Cardinal-McTeague;IbyK.Wurdack.Line drawings: E by Alice Tangerini,K byAnitaWalsmit Sachs,used with permissionfrom the NaturalisBiodiversity Center,Leiden,Netherlands.(Abbreviations:an =annularnectary;d= dimorphic filamentous stamens; in = interstaminal nectaries; r = receptacle. Scale bars = 1 mm).