Carapichea Aubl. (Aublet 1775: 167) [nom. rej. versus Cephaelis Sw. (Swartz 1788)]

Lachenaud, Olivier & Delprete, Piero, 2022, Revision of Carapichea (Rubiaceae - Psychotrieae) in the Guianas, with two new combinations and transfer of three species to Notopleura, Plant Ecology and Evolution 155 (2), pp. 275-300 : 275

Carapichea Aubl. (Aublet 1775: 167) [nom. rej. versus Cephaelis Sw. (Swartz 1788)]

Chesnea Scop. ( Scopoli 1777: 119), nom. superfl. illeg. - Type species: Carapichea guianensis Aubl.

Ipecacuanha Arruda (in Koster 1816: 497), nom. nud. - Type species: Ipecacuanha officinalis Arruda, nom. illeg. [= Carapichea ipecacuanha (Brot.) L.Andersson]

Nettlera Raf. ( Rafinesque 1838: 147), nom. superfl. illeg. - Type species: Nettlera guianensis (Aubl.) Raf. [= Carapichea guianensis Aubl.]

Ipecacuana Raf. ( Rafinesque 1838: 147), orth. var. - Type species: Ipecacuanha fusca Raf. [= Carapichea ipecacuanha (Brot.) L.Andersson]

Uragoga L. ex Baill. ( Baillon 1879: 324), nom. superfl. illeg. - Lectotype species (designated by Petit 1964: 16): U. ipecacuanha (Brot.) Baill. [= Carapichea ipecacuanha (Brot.) L.Andersson]

Stachyococcus Standl. ( Standley 1936: 144) - Type species: Stachyococcus adinanthus (Standl.) Standl. [= Carapichea adinantha (Standl.) C.M.Taylor]

Type species.

Carapichea guianensis Aubl.

Description of the genus.

Subshrubs, shrubs, or small trees. Raphides present. Stipules interpetiolar, free or shortly connate at base, entire to bifid at apex, rarely multifid ( C. ipecacuanha ), lacking dorsal appendages, persistent on distal nodes, marcescent, and eventually falling off through fragmentation, leaving a well-developed scar or a persistent hardened basal portion. Leaves opposite, rarely ternate ( C. tillettii ), short- to long-petiolate; blades ovate, elliptic, obovate, oblong or narrowly elliptic, papyraceous to coriaceous; secondary veins strongly to weakly prominent; tertiary veins reticulate or subparallel; domatia absent, or present as a continuous line of pubescence along midrib. Inflorescence terminal, rarely pseudoaxillary, few- to many-flowered, variously capitate, subcapitate, spiciform, or thyrsoid and branched to 1 or 2 orders; bracts reduced to very large, free to variously connate, sometimes forming an involucre. Flowers bisexual, usually heterodistylous, protandrous, (4)5-merous. Hypanthium ovoid to obovoid. Calyx tube extremely reduced or cup-shaped, truncate, undulate or lobed, persistent, lobes (when present) small, broadly to narrowly triangular. Corolla tubular, funnelform to hypocrateriform, actinomorphic, white, yellow, orange, or salmon-pink, tube glabrous or pubescent inside; lobes valvate, oblong-ovate, margin entire, acute at apex, thickened or sometimes with horn-like extensions ( C. araguariensis ). Stamens included, partially exserted or well exserted beyond corolla mouth; filaments inserted at the basal ( C. urniformis ), median, or distal portion of the corolla tube, short, equal, glabrous; anthers narrowly elliptic or narrowly oblong or linear, round at base, round or apiculate at apex, dorsifixed near middle. Pollen aperturate. Ovary 2-locular, placenta reduced. Ovules 1 per locule, basally inserted, erect. Disk usually bilobed to the base, sometimes undivided and cylindrical or laterally 5-sulcate ( C. adinantha ). Style included or partially exserted, glabrous; branches 2, oblong or linear. Fruits drupaceous, fleshy, variable in colour (yellow, orange-red, red, purple, maroon, blue, white or cream-white, or black at maturity) with 2 fibrous to woody pyrenes. Pyrenes vertical, plano-convex, ovate to elliptic in outline, dorsal side multi-costate, ventral side longitudinally sulcate or rarely flat.

Morphological characters.

The main diagnostic characters of Carapichea are the marcescent stipules lacking dorsal appendages, lack of ethanol-soluble pigment in the seed testa, and aperturate pollen of a generalized form, corresponding to Types XIV and XVI of Johansson (1992). The genus is rather variable in inflorescence and pyrene characters, as described by Taylor and Gereau (2013). Most species of Carapichea have a bipartite disk. This character was not emphasized by previous authors and is often not even mentioned in their descriptions, though it is well depicted on illustrations of C. tillettii ( Steyermark 1972: 496, figure 70), C. urniformis ( Steyermark 1972: 557, figure 74), and C. vasivensis and C. pacimonica ( Steyermark 1974, figures 234, 240). Among species investigated for this character, the only exceptions are C. cardenasiana , C. ipecacuanha , and C. panurensis , which have an entire disk, and C. adinantha , which has an undivided, laterally 5-sulcate disk. We were not able to verify the shape of the disk in C. fimbriflora , C. lucida , C. maturacensis , and C. verrucosa . Among related genera, bipartite disks also occur in some species of Notopleura (see above) and in two recently described species of Rudgea Salisb.: R. glomerulata Zappi & O.Lachenaud and R. itoupensis O.Lachenaud ( Lachenaud et al. 2022).

Position within the tribe and delimitation of Carapichea . Carapichea has been included in the Palicourea complex of the tribe Psychotrieae s.l. by Andersson (2002) and Lachenaud (2019). This complex has been treated as the tribe Palicoureeae by Robbrecht and Manen (2006), Razafimandimbison et al. (2014), and Taylor and Bruniera (2018), and includes Carapichea , Chassalia Comm. ex Poir., Eumachia DC. [= Chazaliella E.M.A.Petit & Verdc., Margaritopsis C. H.Wright], Geophila D.Don, Hymenocoleus Robbr., Notopleura , Palicourea Aubl. s.l., Puffia Razafim. & B.Bremer, and Rudgea . Phylogenetic studies strongly support the monophyly of Carapichea , albeit with limited sampling ( Andersson 2002; Razafimandimbison et al. 2014; Bruniera 2015). The genus appears either as sister to Eumachia ( Andersson 2002; Bruniera 2015; as Margaritopsis ) or as sister to a clade including Eumachia , Chassalia , Geophila , Puffia , and Hymenocoleus ( Razafimandimbison et al. 2014) with low support in all cases.

Distribution and ecology.

According to the present circumscription, Carapichea includes at least 22 species that are found mostly in the Amazon basin and the Guianas, with two species ( C. affinis and C. ipecacuanha ) extending to Central America, one ( C. ipecacuanha ) extending to the Cerrado Biome of Central Brazil, and a single species ( C. lucida ) endemic to the Atlantic Forest of Brazil. The species occur in lowland or lower montane forest habitats (up to 1570 m but mostly below 1000 m), either on drained or seasonally flooded soils. Eight species occur in the Guianas; a ninth one, C. araguariensis , is to be expected there and has been included in the treatment below.

Infrageneric classification.

No infrageneric taxa are formally recognised in Carapichea , but the species may be arranged in six groups (Table 1 ), separable by characters in the key below, and largely based on those proposed by Taylor and Gereau (2013). We have usually kept the group names used by these authors, although their Pacimonica group is better called the Ligularis group now that C. pacimonica is a synonym of C. ligularis . Their Altsonii group is not maintained here, since, as discussed above, three of its species are transferred to Notopleura , while the last one, C. urniformis , is included in the Carapichea group of which it has all the key characters. Also transferred to the Carapichea group are C. tillettii (see Notes under this species) and C. fimbriflora . The latter species, from Brazil, is very poorly known, but its leaf venation matches the Carapichea group, rather than the Ligularis group in which it was placed by Taylor and Gereau (2013).