Gaulettia Sothers & Prance, 2014

Sothers, Cynthia, Prance, Ghillean T., Buerki, Sven, Kok, Rogier De & Chase, Mark W., 2014, Taxonomic novelties in Neotropical Chrysobalanaceae: towards a monophyletic Couepia, Phytotaxa 172 (2), pp. 176-200 : 181-182

Gaulettia Sothers & Prance , gen. nov.

Diagnosis: Gaulettia shares affinities with Couepia and Hirtella but the pronounced reticulate venation of Gaulettia distinguishes it from both Couepia in the restricted sense used here and Hirtella . The receptacle is often narrow-elongate as in some species of Couepia ; but in Hirtella most species have shallow open receptacles. It shares with Couepia s.s. and Hirtella the ovary at the mouth of the receptacle. The fruits of Gaulettia are hard and of two types, verrucose or puberulous and differs from Hirtella , which are fleshy with a smooth, glabrous epicarp. Gaulettia is easily distinguished from Licania by the shape of the receptacle, which is shorter and more open in Licania , and by the ovary, positioned at the base of the receptacle in Licania .

Type: Gaulettia parillo (DC.) Sothers & Prance

Trees or shrubs; leaf venation reticulate on the abaxial surface and with hair-filled stomatal cavities, leaves often with a whitish bloom on abaxial surface; prominent parallel secondaries at 90° to primaries; pair of glands at base of leaf; inflorescence and axis densely ferrugineous (except for G. elata ); inflorescence panicles or racemes; calyx lobes acuminate (rounded to acute in G. racemosa and rounded in some G. cognata ); receptacle 3(–4)–10(–22) mm long, receptacle interior glabrous except for the deflexed hairs at the throat; petals 5, white; stamens 12–65, in a complete circle, semi-circle or unilaterally placed around the disk; style mostly glabrous, pubescent at base only; ovary villous to densely villous, unilocular, inserted at mouth of receptacle; fruit hard, epicarp pubescent ( G. canomensis , G. parillo ) or verrucose ( G. amaraliae , G. elata , G. foveolata , G. racemosa , G. cognata , G. canescens ). The fruit of G. steyermarkii is known only from an immature specimen, which is sparsely pubescent.

Distribution and habitat: —Throughout the Amazonian region of Peru, Ecuador, Colombia, Venezuela, Brazil and the Guianas.

Etymology: —The epithet refers to the word ‘gaulette’, a vernacular name often used in French Guiana for G. parillo and other species of Chrysobalanaceae .

Notes: —In his revision of Neotropical Chrysobalanaceae, Prance (1972a) assigned four species to the Couepia parillo superspecies: C. canomensis , C. parillo , C. steyermarkii and C. foveolata . He defined the group by the conspicuously reticulate venation with silver-grey pubescence in the space between the veins on the underside of the leaves, prominent parallel tertiary venation connecting secondary veins, a racemose inflorescence with a dense ferrugineous-brown hirtellous pubescence, a slender cylindrical receptacle tube (usually with villous hairs on the exterior), and fruits with a tomentose epicarp. He cited two species as also having this distinct leaf reticulation, C. elata and C. racemosa , but did not place them in this group. Couepia amaraliae was unknown at the time, and C. canescens was considered a synonym of C. cognata (as Parinari canescens ), which he also did not place in the superspecies group. However, in subsequent publications he assigned C. racemosa , C. amaraliae , C. cognata and C. canescens to this group ( Prance 1974b, 1989).

The nine species of Gaulettia occur mostly in habitats distinct from those of Couepia . Although G. parillo , G. canomensis and G. racemosa occur in terra firme forest, they are more commonly found in open areas such as secondary forests and sandy soil habitats. Gaulettia elata is the only true lowland wet rainforest species of Gaulettia , found in terra firme forests with clay soils, and occasionally in campinarana forests. Gaulettia foveolata occurs in riverine forests, G. amaraliae , G. steyermarkii , G. cognata and G. canescens all occur in drier, sandy soil habitats such as savanna, campina, campinarana or high elevation habitats. Two species, G. steyermarkii and G. foveolata , are endemic to the Guayana Highland, a region known for its high plant endemicity.

Key to species of Gaulettia :

1. Leaves with prominent parallel intercostal (tertiary) venation; inflorescences racemose; flowers usually subsessile or pedicels ca. 1–2 mm long; stamens in almost complete circle,> 40; mature fruit with persistent yellow-brown pubescence; Amazon region in rainforests and secondary vegetation..................................................................................................................................................2

- Leaf without prominent parallel intercostal (tertiary) venation or obscured by dense pubescence; inflorescences panicles or racemes; flowers with pedicels 1–3.5 mm long; stamens 12–40, unilateral or in 2/3 circle; mature fruit verrucose (unknown in G. steyermarkii , young fruit pilose); savannas or white sand habitats in northern South America and Amazon region........................3

2. Leaf size 5.0–15.5 x 1.7–5.8 cm; receptacle 11–22 mm long; stamens 45–62 ................................................................... G. parillo

- Leaf size 8.5–18.0 x 3.0–8.0 cm; receptacle 5.5–10.0 mm long; stamens 40–51 ........................................................ G. canomensis

3. Leaf reticulate, with indistinct stomatal cavities on abaxial surface; inflorescences racemose; flowers distinctly pedicellate, pedicel 2.5–3.5 mm long, slender; receptacle with sparse silver-grey pubescence; stamens 35–40; canopy tree of (mostly) terra firme forest........................................................................................................................................................................................ G. elata

- Leaf strongly reticulate, often with distinct stomatal cavities on abaxial surface; inflorescences racemose or paniculate ( G. racemosa , G. amaraliae , G. cognata ); flowers with pedicels 1–3 mm long; receptacle with dense pubescence (reddish-brown villous); stamens 12–40; small tree or shrub of savanna, tepui, campina (except for G. racemosa ).................................................4

4. Leaf on abaxial surface always covered in lanate pubescence, obscuring tertiaries; inflorescences densely tomentose; stamens 12–25, unilateral.................................................................................................................................................................................5

- Leaf on abaxial surface not covered in lanate pubescence, not obscuring tertiaries; inflorescences brown-ferrugineous tomentellous; stamens 20–40, unilateral or in 2/3 of a circle....................................................................................................................................6

5. Inflorescences (usually) paniculate; receptacle 5–8 mm long; pedicels ca. 3 mm long; stamens 12–25; shrub or small tree of savannas.............................................................................................................................................................................. G. cognata

- Inflorescences racemose; receptacle 3–4 mm long; pedicels to 1 mm long; stamens 12–16; small tree of high elevation forest and tepuis................................................................................................................................................................................ G. canescens

6. Leaf coriaceous, deeply reticulate, parallel secondaries not prominent.............................................................................................7

- Leaf chartaceous, reticulate, parallel secondaries prominent.............................................................................................................8

7. Receptacle length 3–4 mm; stamens 35–40; campinas and campinaranas, Brazil......................................................... G. amaraliae

- Receptacle length 8–10 mm; stamen number unknown; tepui and montane forest, Venezuela.................................. G. steyermarkii

8. Receptacle 5.0– 7.5 mm long; stamens 24–30; tree or shrub of secondary, terra firme and riverine forest in central and western Amazon (not Guianas)..................................................................................................................................................... G. racemosa

- Receptacle 8.0–10.0 mm long; stamens ca. 20; tree of riverine forest in western Amazon/upper Rio Negro region...... G. foveolata