Abstract
Theobroma (Malvaceae, Byttnerioideae), the cacao genus, has a taxonomic history spanning over two centuries. Currently, it comprises 23 species of trees from lowland forests from the Tropical Americas. Herrania, a closely related genus described later, includes 17 additional species commonly referred to as “wild cacaos.” Phylogenetic relationships and morphological circumscriptions between Theobroma and Herrania have been the subject of debate. While Herrania has traditionally been treated as a separate genus based on evident morphological differences in leaf and petal features, it shares similarities with Theobroma in terms of habit, inflorescence, and fruit types. Recent phylogenetic evidence, incorporating a broader taxonomic sampling and a total-evidence analysis, suggested that Theobroma is paraphyletic, with Herrania nested within it. This finding supports the restoration of a classical circumscription of Theobroma wherein Herrania is considered a section of the former genus. Here, we provide a detailed account of the taxonomic history at infrageneric levels and propose one new subsection, two names at new ranks (to better allocate the diversity within T. sect. Herrania), and nine new combinations encompassing this expanded circumscription of Theobroma. In our study, we delimit Theobroma with forty species divided into six sections: T. sect. Glossopetalum (14 spp.), T. sect. Herrania (17 spp.), T. sect. Oreanthes (5 spp.), T. sect. Rhytidocarpus (1 sp.), T. sect. Telmatocarpus (2 spp.), and T. sect. Theobroma (1 sp.). Furthermore, we recognize three subsections within T. sect. Herrania. Alongside these newly proposed changes, we present a section-level identification key and provide diagnostic characters for each taxon.
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Introduction
Theobroma L. (Malvaceae, Byttnerioideae) has a botanical history spanning two centuries. Comprising 23 species of understory trees native to Neotropical forests (Cuatrecasas, 1964; Colli-Silva & Pirani, 2020; Santamaría-Aguilar et al., 2023), mostly from lowland areas, Theobroma stands out from other Malvaceae for its baccate fruits with axial placentation and large brownish seeds. Theobroma species also hold immense cultural, economic, and culinary significance. Notably, the seeds of its most renowned species, the cacao tree (T. cacao L.), are the source of chocolate, a globally cherished food. In fact, the cultural history of cacao dates back to ancient Mesoamerican civilizations, where it was considered a divine gift (hence the genus name assigned by Linnaeus, which means “food of the gods”) and used in various rituals and ceremonies (Coe & Coe, 2013). In modern times, the global chocolate industry has become a multi-billion-dollar enterprise, supporting livelihoods in numerous cocoa-producing regions around the world (Sahagún et al., 2018).
A closely related genus, Herrania Goudot (Goudot, 1844) includes 17 species also known as “wild cacaos” (Schultes, 1958). Morphologically, Herrania shares traits with species of Theobroma with regard to the understory tree habit, cauliflory, and complex flower structure, featuring unguiculate and cucullate petals and a staminal tube with alternating stamens and staminodes. As in Theobroma, these staminodes are often petaloid, and are interspersed between groups of fertile stamens arranged in dyads, triads, or tetrads, connected by the filament, resulting in what is commonly referred to as “2–3–4-antheriferous” stamens (Schumann, 1886; 1895; Schultes, 1958; Cuatrecasas, 1964). Furthermore, both Theobroma and Herrania exhibit baccate fruits (see Roth, 1977), usually spherical, conical, or cylindrical, with diverse epicarp ornamentation.
The name Theobroma was first mentioned by Linnaeus in his Genera Plantarum (1737: 350). Subsequently, Linnaeus (1738: 379), recognized two species with the phrase names “Theobroma foliis integerrimis” and “Theobroma foliis serratis.” These polynomials were repeated later in Linnaeus’s Species Plantarum (1753: 782) when he published the binomials T. cacao L. and T. guazuma L. (=Guazuma ulmifolia Lam.), respectively. The genus Herrania was later described by Goudot (1844). Based on collections initially assigned to Theobroma (or Abroma Jacq.), Goudot emphasized that his new genus represented an intermediate between Guazuma Mill. and Theobroma, resembling the former in the disposition of the stamens in the staminal tube but differing from it in fruit form. Moreover, Herrania diverged from Theobroma in sepal count, stamen arrangement, seed characteristics, and cotyledon appearance, despite having a very similar fruit.
Bernoulli’s (1869) monograph on Theobroma was the first to propose an infrageneric classification. Bernoulli created five sections (Table 1), which have formed the basis for subsequent classifications of the genus (e.g., Schumann, 1886, 1895; Pittier, 1930). Schumann (1886, 1895) considered Herrania to be a section of Theobroma, and thus proposed T. sect. Bubroma K.Schum., while also recognizing T. sect. Eutheobroma (invalid name; see below). Pittier (1930) reduced in rank Bernoulli’s (1869) sections, which he considered to be subsections (Table 1). Schumann and Pittier’s systems both strongly relied on stamen arrangement, whether in dyads or triads, a common feature in Theobroma but variable in Herrania, where triads or tetrads can appear in the same flower. Thus, T. sect. Eutheobroma [sic] encompassed species with stamens in dyads, while T. sect. Bubroma consisted of species with stamens in triads. Pittier’s (1930) subsections were based on staminode morphology, distinguishing between linear and expanded forms, as well as petal attributes.
In the 20th century, Schultes (1958) and Cuatrecasas (1964) established the current taxonomy and nomenclature of Herrania and Theobroma, both maintaining Herrania as a separate genus. Cuatrecasas (1964) provided detailed insights into the nomenclatural status of Theobroma at infrageneric levels, including the designation of types for several of the recognized sections. Bernoulli’s sections were retained by Cuatrecasas, but Schultes (1958) introduced two new sections within Herrania sensu Goudot (1844): H. sect. Herrania and H. sect. Subcymbicalyx R.E.Schult. The former section encompassed species having a patelliform calyx, while the latter included species with a cupuliform one. Branch architecture and seed germination played significant roles in infrageneric classification, particularly for Theobroma (Ducke, 1940; Cuatrecasas, 1964).
With the advent of molecular phylogenetics, the monophyly of Theobroma and Herrania became uncertain due to limited sampling and low branch support (Whitlock & Baum, 1999; Sousa Silva & Figueira, 2005; Borrone et al., 2007; Richardson et al., 2015). Paraphyly has been observed in certain sections, such as T. sect. Glossopetalum Bernoulli and H. sect. Subcymbicalyx (Sousa Silva & Figueira, 2005; Borrone et al., 2007). A recent study (Bossa-Castro et al., 2024) presented a new phylogeny based on the sampling of nearly all species of Theobroma and Herrania, using both morphological and molecular (nuclear) datasets, the latter consisting of WRKY transcription-factor gene sequences. This study concluded that Theobroma is paraphyletic with regard to Herrania, a result that had strong branch support. The study also confirmed the monophyly of most sections described by Bernoulli (1869) and Cuatrecasas (1964). Herrania sect. Subcymbicalyx sensu Schultes (1958), however, was not confirmed, but instead is paraphyletic.
When treated as separate genera, Theobroma and Herrania exhibit notable morphological differences, including branch architecture (sympodial in Theobroma vs. monopodial in Herrania), leaf blade division (simple in Theobroma vs. palmately compound in Herrania), petiole length (<3 cm long in Theobroma vs. >10 cm long in Herrania), and petal ligule length (not more than 2× the petal claw length in Theobroma vs. more than 2× in Herrania). However, the new phylogeny presented by Bossa-Castro et al. (2024), along with earlier circumscriptions proposed by Schumann (1886; 1895), Pittier (1930), and Ducke (1940, 1953) for Theobroma sensu lato (including Herrania), gained support over the scenario suggested by Schultes (1958) and Cuatrecasas (1964). Notably, both Theobroma and Herrania share common morphological features, such as strongly cucullate and relatively thick petals (although plesiomorphic or apomorphic conditions of this feature remain unclear), staminodes (present in both genera, ranging from linear to petaloid but never bifid as seen in Guazuma, another closely related genus), and the unique baccate fruit characterized by a mesocarp divided into two portions by a parenchimatic, which consists of a multiseriate layer of sclerenchyma cells that separates the outer and the inner portion of the mesocarp (see Roth, 1977).
Additional diagnostic features apparently unique to Theobroma + Herrania, not found in close relatives, include wood anatomical characteristics (presence of small, bordered pits, mostly solitary vessels, and non-storied rays, as opposed to irregularly storied rays in Guazuma), seed and cotyledon characteristics (purplish seeds with folded and corrugated cotyledons), and chromosome numbers, which are identical in both groups (2n = 20) (Cuatrecasas, 1964). Moreover, successful hybridizations between species of Theobroma and Herrania have been reported (Addison & Tavares, 1952; Ascenso, 1964; Sousa Silva et al., 2004). The evolution of selected morphological characters within Theobroma is discussed by Bossa-Castro et al. (2024), where they suggest that Herrania species would represent extreme cases of flower evolution with elongated petal ligules and strongly ridged fruits. Cauliflory would also have been evolved from an exclusively ramiflorous condition in early-diverging lineages of Theobroma (as a plesiomorphic condition) towards an exclusively cauliflorous condition observed in T. sect. Herrania (Goudot) K.Schum. and T. sect. Oreanthes Bernoulli.
The present study proposes an infrageneric classification that re-establishes Theobroma sensu lato, in which Herrania is included as a section of Theobroma. This decision is based on newly available evidence and considers previous authors who considered Herrania congeneric with Theobroma solely based on morphology (Schumann, 1886, 1895; Pittier, 1930; Ducke, 1940, 1953) and on the comparison of the morphological features described above. Figure 1 summarizes the main changes under the new phylogenetic framework derived from the study of Bossa-Castro et al. (2024).
Materials & Methods
Leaf terminology follows the framework established by Ellis et al. (2009), while descriptions of flower and fruit morphology drew from the works of Roth (1977), and Weberling (1989). For precise terminology concerning the petal ligules of Theobroma and Herrania, we followed Schultes (1958) and Cuatrecasas (1964). The leaves in Theobroma sensu lato exhibit two main forms: they are either simple or palmately compound. Additionally, we categorized leaf(-let) margins as either untoothed—characterized by a lack of vascularized projections or teeth along the edge—or toothed, indicating the presence of vascularized projections. Within the toothed-margin category, we further distinguished whether the veins reached the margin of the leaf or protrude beyond it. Lastly, we treated the petals as unguiculate structures, comprising a lower expanded and cucullate portion defined as the claw, and an upper, filiform segment referred to as the ligule. The proportions of claw length with respect to the ligule length (i.e., the number of times the ligule is longer than the claw) were also significant features that aid in distinguishing taxa at various ranks within our classification framework. Additionally, we considered petal venation, specifically the number of veins vascularizing the claw, as another important feature for infrageneric classification.
Taxonomic Treatment
Theobroma L., Sp. Pl. 782. [1 May] (1753). TYPE (designated by Hitchcock & Green, 1929: 177): Theobroma cacao L.
Cacao Mill., Gard. Dict. Abr. ed. 4: s.p. (1754). TYPE: Not designated.
Herrania Goudot, Ann. Sci. Nat. Bot., sér. 3, 2: 230 (1844). TYPE (designated by Schultes, 1953: 77): Herrania albiflora Goudot.
Lightia R.H.Schomb., Rep. Brit. Assoc. Advancem. Sci. 1844(2): 71 (1845). TYPE: Lightia lemniscata R.H.Schomb.
Brotobroma H.Karst. & Triana, Nuev. Jen. Esp. 11 (1854). TYPE: Brotobroma aspera H.Karst. & Triana.
Tribroma O.F.Cook, J. Washington Acad. Sci. 5: 288 (1915). TYPE: Tribroma bicolor O.F.Cook.
Diagnostic comments. Theobroma sensu lato is characterized by flowers with unguiculate and deeply cucullate petals divided into two portions: a lower expanded petal claw and an upper linear to filiform ligule. The stamens are grouped in dyads, triads, or tetrads, with one cluster of staminodes between each stamen group, forming a staminal tube. The baccate fruit has a fibrous outer pericarp and pulpy internal portions, separated by a multiseriate layer of sclerenchyma cells (see Roth, 1977). The seeds are purplish with folded and deeply corrugated cotyledons, and the chromosome number is 2n = 20.
Under this broadened circumscription, the number of Theobroma species increases from 23 to 40, distributed across six sections: T. sect. Glossopetalum (14 spp.), T. sect. Herrania (17 spp.), T. sect. Oreanthes (5 spp.), T. sect. Rhytidocarpus Bernoulli (1 sp.), T. sect. Telmatocarpus Bernoulli (2 spp.), and T. sect. Theobroma (1 sp.) (Table 1). An identification key for the sections and subsections of Theobroma sensu lato is provided below, to better demonstrate the morphological and geographic features that are common to the species. A comprehensive taxonomic revision, accounting for synonyms and infraspecific taxonomy, is currently being prepared.
Key to the sections and subsections of Theobroma sensu lato
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1. Trees with monopodial growth; leaves palmately-compound; petioles >3 cm long; stipules >1.5 cm long; inflorescences cauliflorous, usually 5–10–many-flowered; calyx 3-merous, crimson to purplish, exceptionally ochraceous or ferruginous or cream; petal ligules filiform, at least 2× longer than the claw; fruit epicarp irregularly 10-ridged, usually yellowish-green when ripe………………………………………T. sect. Herrania
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2. Leaflets ovate, leaflet base convex, margin entire; petals with 7 veins; staminodes lanceolate………………………………………………………..........................................................................................……..T. subsect. Dugandia
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2. Leaflets elliptic-oblong, obovate or lobate, exceptionally ovate, leaflet base decurrent, straight or cuneate, usually with the secondary veins protruding beyond the leaf margin; petals with 4–6-veins, rarely 7-veined.
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3. Leaflet margin usually partially to entirely toothed, veins protruding beyond the leaf margin, forming conspicuous apicules >2 mm long; inflorescences 10–many-flowered; corolla usually glabrous to sparsely pubescent; petal ligules >10× longer than the petal claw. Mostly from the Amazon Basin…………………………………………………................................................................................……….T. subsect. Subcymbicalyx
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3. Leaflet margin untoothed, exceptionally toothed at the apex, veins protruding beyond the leaf margin, but forming apicules <2 mm long; inflorescences 4–10- or many-flowered; corolla sparsely pubescent, rarely glabrous; petal ligules <10× longer than the petal claw. Mostly from the Pacific Dominion (sensu Morrone, 2014), northern South America to Panama……………………………………………..T. subsect. Herrania
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1. Trees with sympodial growth; leaves simple; petioles <3 cm long; stipules <1.5 cm long; inflorescences cauliflorous or ramiflorous, few- or 10–many-flowered; calyx 3–5-merous, ochraceous to ferruginous, occasionally crimson to purplish; petal ligules widened and expanded, up to 2× longer than the claw; fruit epicarp smooth or 5-ridged, usually ochraceous to ferruginous when ripe.
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4. Leaves pulvinate, glabrous abaxially, brochidodromous; calyx yellowish green externally; petals purplish, pink to light red, yellow or crimson; corolla glabrous; fruit epicarp glabrous, variously shaped……………………………............................................................……T. sect. Theobroma
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4. Leaves not pulvinate, pubescent abaxially, eucamptodromous to craspedodromous; calyx purplish or ochraceous to ferruginous externally; corolla pubescent, exceptionally glabrous; fruit epicarp smooth or deeply ridged, pubescent.
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5. Petals crimson, orange to yellow, 7–more-veined, petal ligules almost equal to or longer than the petal claws; staminodes petaloid, elliptic-ovate; fruit epicarp smooth, rugose, not ridged……………………………………………………………............................................................….T. sect. Glossopetalum
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5. Petals crimson to purplish, 3–6-veined; petal ligules shorter than petal claws in length; staminodes filiform to lanceolate; fruit 5–10-ridged.
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6. Leaf acumen up to 10× longer than leaf blade length; inflorescences few-flowered; petals orbicular, 4–6-veined, <7 cm diam; fruit orbicular, shortly 5–10-ridged; germination hypogeal……………………………………………….......................................……………T. sect. Telmatocarpus
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6. Leaf acumen always >10× longer than leaf blade length. Inflorescences many-flowered; petals 1–3-veined; fruit sub-orbicular to cylindrical, 5–10-ridged, epicarp smooth or tuberculate, usually >7 cm diam; germination epigeal.
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7. Leaves widely ovate, base cordate, 3-nerved. Inflorescences ramiflorous, 4–10-flowered; petals crimson to purplish, petal claws 1–2-nerved; fruit markedly tuberculate, 10-ridged, glabrous, yellowish-green when ripe……………………………………………………T. sect. Rhytidocarpus
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7. Leaves elliptic-ovate to elliptic-oblong, base rounded, 1–2-nerved; inflorescences cauliflorous, 1–3-flowered or 10–more-flowered; petals pinkish to crimson; petal claws 3–more-nerved; fruit smooth to slightly 5-ridged, not tuberculate, densely pubescent, ochraceous to ferruginous when ripe…………………………..............................................................................................................................................….T. sect. Oreanthes
1. Theobroma sect. Theobroma
Theobroma sect. Cacao (Mill.) Bernoulli, Uebersicht Theobroma 6 (1869), nom. illeg. Theobroma subsect. Cacao (Mill.) Pittier, Rev. Int. Bot. Appl. Agric. Trop. 10(110): 779 (1930). TYPE: Not designated.
Theobroma sect. Eutheobroma K.Schum. in Martius, Fl. Bras. 12(3): 70 (1886), nom. inval.
Diagnostic comments. Leaves simple, pulvinate, glabrous abaxially, brochidodromous; calyx yellowish-green externally, petals purplish, pink to light red, yellow, or crimson; corolla glabrous; fruit variously shaped, slightly ridged depending on the cultivar, epicarp glabrous. One species:
1.1. Theobroma cacao L., Sp. Pl. 782 (1753).
2. Theobroma sect. Telmatocarpus Bernoulli, Uebersicht Theobroma 11 (1869). Theobroma subsect. Telmatocarpus (Bernoulli) Pittier, Rev. Int. Bot. Appl. Agric. Trop. 10(110): 779 (1930). TYPE: Theobroma microcarpum Mart.
Diagnostic comments. Leaves simple, acumen less than 10× longer than the leaf-blade length; inflorescences few-flowered; petals with 4 or more veins, petal ligules almost lacking; germination hypogeal. Two species:
2.1. Theobroma gileri Cuatrec., Rev. Int. Bot. Appl. Agr. Trop. 33(373–374): 562, t. 1 (1953).
2.2. Theobroma microcarpum Mart. in Buchner, Repert. Pharm. 35: 24 (1830) (“microcarpa”).
3. Theobroma sect. Rhytidocarpus Bernoulli, Uebersicht Theobroma 9 (1869). Theobroma subsect. Rhytidocarpus (Bernoulli) Pittier, Rev. Int. Bot. Appl. Agric. Trop. 10(110): 779 (1930). TYPE (designated by Cuatrecasas, 1964: 458): Theobroma bicolor Bonpl.
Diagnostic comments. Leaves simple, cordate at the base, less than 10× longer than leaf-blade length; petals and staminodes pink to light red, petals with 1–2 veins; fruit epicarp irregularly and prominently tuberculate. One species:
3.1. Theobroma bicolor Bonpl., Pl. Aequinoct. 1(4): 104, t. 30 (1806 [1808]).
4. Theobroma sect. Oreanthes Bernoulli, Uebersicht Theobroma 7 (1869) (“Oraeanthes”). Theobroma subsect. Oreanthes (Bernoulli) Pittier, Rev. Int. Bot. Appl. Agric. Trop. 10(110): 779 (1930). TYPE (designated by Cuatrecasas, 1964: 467): Theobroma speciosum Willd. ex Spreng.
Diagnostic comments. Leaves simple, acumen more than 10× longer than leaf-blade length; inflorescences many-flowered; petals with 1–3 veins, petal ligules sessile and large; germination epigeal. Five species:
4.1. Theobroma bernoullii Pittier, Repert. Spec. Nov. Regni Veg. 13: 319 (1914) (“Bernouillii”).
4.2. Theobroma glaucum H.Karst., Linnaea 28(4): 447 (1857 [1856]).
4.3. Theobroma speciosum Willd. ex Spreng., Syst. Veg. 3: 332 (1826).
4.4. Theobroma sylvestre (Aubl.) Mart. in Buchner, Repert. Pharm. 35: 24 (1830).
4.5. Theobroma velutinum Benoist, Bull. Mus. Hist. Nat. Paris 27: 113 (1921).
5. Theobroma sect. Glossopetalum Bernoulli, Uebersicht Theobroma 11 (1869). Theobroma subsect. Glossopetalum (Bernoulli) Pittier, Rev. Int. Bot. Appl. Agric. Trop. 10(110): 779 (1930). TYPE: Theobroma angustifolium DC. (here designated). Note: Although Cuatrecasas (1964: 526) stated that the type of this section was Theobroma grandiflorum DC., this species was not one of the species included by Bernoulli (1869) and cannot serve as type of this name.
Theobroma sect. Bubroma K. Schum., in Engler & Prantl, Nat. Pflanzenfam. 3(6): 89 (1890). TYPE: Theobroma angustifolium DC. (here designated).
Theobroma sect. Andropetalum Cuatrec., Contr. U.S. Natl. Herb. 35(6): 579 (1964), syn. nov. TYPE: Theobroma mammosum Cuatrec. & J.León
Diagnostic comments. Leaves simple; inflorescences 1–3–10-flowered, exceptionally 11–many-flowered; petals crimson, with 7–many veins, petal ligules almost equal to or longer than the petal claw; staminodes elliptic or ovate; fruit smooth or rugose, exceptionally tuberculate. Fourteen species:
5.1. Theobroma angustifolium DC., Prodr. 1: 484 (1924).
5.2. Theobroma canumanense J.M.Pires & R.L.Fróes ex Cuatrec., Contr. U.S. Natl. Herb. 35(6): 577, fig. 43 (1964).
5.3. Theobroma chocoense Cuatrec., Contr. U.S. Natl. Herb. 35(6): 543 (1964).
5.4. Theobroma cirmolinae Cuatrec., Notas Fl. Colombiana 6: 5, Figs. 1–5 (1944).
5.5. Theobroma flaviflorum Aguilar & D.Santam., Syst. Bot. 48(2): 315, Figs. 1, 2, 3A, 4R, 7T (2023).
5.6. Theobroma grandiflorum (Willd. ex Spreng.) K.Schum. in Martius, Fl. Bras. 12(3): 76, t. 17 (1886).
5.7. Theobroma hylaeum Cuatrec., Contr. U.S. Natl. Herb. 35(6): 570, Figs. 25F, 39D (1964).
5.8. Theobroma mammosum Cuatr & J.León, Bol. Técn. Inst. Interamer. Ci. Agric. 2: 1, Figs. 1–7 (1949).
5.9. Theobroma nemorale Cuatrec., Revista Acad. Colomb. Ci. Exact. 8(32): 487, Fig. 4 (1952).
5.10. Theobroma obovatum Klotzsch ex Bernoulli, Uebersicht Theobroma 14, t. 7, Fig. 3 (1869).
5.11. Theobroma simiarum Donn.Sm., Bot. Gaz. 25(3): 145 (1898).
5.12. Theobroma sinuosum Pav. ex Huber, Bull. Herb. Boissier, sér. 2, 6: 274 (1906).
5.13. Theobroma stipulatum Cuatrec., Fieldiana, Bot. 27(1): 84, Fig. 7 (1950).
5.14. Theobroma subincanum Mart. in Buchner, Repert. Pharm. 35: 23 (1830).
6. Theobroma sect. Herrania (Goudot) K.Schum. in Martius, Fl. Bras. 12(3): 70 (1886). Herrania Goudot, Ann. Sci. Nat., Bot., sér. 3, 2: 230 (1844). TYPE: Herrania albiflora Goudot. Theobroma albiflorum (Goudot) De Wild.
Diagnostic comments. Trees with monopodial growth; leaves palmately-compound, petioles more than 3 cm long; stipules more than 1.5 cm long; inflorescences cauliflorous, usually 5–10–more-flowered; calyx 3-merous, crimson to purplish, exceptionally ochraceous or ferruginous, or cream; petal ligules filiform, at least 2× longer than the petal claw; fruit epicarp deeply 10-ridged, usually yellowish-green when ripe.
In order to enrich the differentiation among various groups within T. sect. Herrania, and considering the presence of both morphological and geographical distinctions, we have classified the diversity of T. sect. Herrania in three subsections:
6.1. Theobroma subsect. Dugandia Colli-Silva, subsect. nov. TYPE: Theobroma dugandii (García-Barr.) Colli-Silva.
Diagnostic comments. Leaflets ovate, base shape convex, veins touching but not extending beyond the leaf margin; petals with 7 veins; staminodes lanceolate. One species:
6.1.1. Theobroma dugandii (García-Barr.) Colli-Silva, comb. nov. Herrania dugandii García-Barr., Caldasia 1(2): 59, Fig. 3 [“Dugandii”] (1941).
6.2. Theobroma subsect. Subcymbicalyx (R.E.Schult.) Colli-Silva, stat. nov. Herrania sect. Subcymbicalyx R.E.Schult., J. Arnold Arbor. 39: 229 (1958). TYPE (designated by Schultes, 1958: 229): Herrania nitida (Poepp.) R.E.Schult. Theobroma asperum (H.Karst. & Triana) K.Schum. ex C.J.J.Hall.
Diagnostic comments. Leaflet margin usually toothed (throughout or only at the apex), veins extending beyond the leaf margin, forming apicules >2 mm long; inflorescences 10-many-flowered; corolla usually glabrous to sparsely pubescent; petal ligules more than 10× longer than the petal claw. Six species:
6.2.1. Theobroma asperum (H.Karst. & Triana) K.Schum. ex C.J.J.Hall., Cacao, ed. 2, 49 (1932) (“aspera”). Note: The name Theobroma nitidum (Poepp.) K.Schum., in Mart. Fl. Bras. 12(3): 71 (1886), nom. illeg. [non Theobroma nitidum Bernoulli, Ueberischt Theobroma: 15 (1869)] is originally based on Abroma nitida Poepp., Nov. Gen. Sp. Pl. 3: 74 (1845). However, it cannot be utilized because this combination is a later homonym to Theobroma nitidum Bernoulli. Schultes (1958: 257) tentatively proposed the combination to Herrania nitida (Poepp.) R.E.Schult., but according to the findings of this study, the correct nomenclature for this species is as described herein. A comprehensive nomenclatural conspectus will be included in an ongoing taxonomic treatment that we are currently preparing.
6.2.2. Theobroma cuatrecasasianum (García-Barr.) Colli-Silva, comb. nov. Herrania cuatrecasasiana García-Barr., Caldasia 1(2): 57, t. 2. (“Cuatrecasana”) (1941).
6.2.3. Theobroma kanukuense (R.E.Schult.) Colli-Silva, comb. nov. Herrania kanukuensis R.E.Schult., Caldasia 2(6): 11 (1943).
6.2.4. Theobroma mariae (Mart.) K.Schum. in Martius, Fl. Bras. 12(3): 71 (1886).
6.2.5. Theobroma nycterodendron (R.E.Schult.) Colli-Silva, comb. nov. Herrania nycterodendron R.E.Schult., Caldasia 2(6): 21 (1943).
6.2.6. Theobroma tomentellum (R.E.Schult.) Colli-Silva, comb. nov. Herrania tomentella R.E.Schult., Bot. Mus. Leafl. 16(8): 213, t. 32 (1954).
6.3. Theobroma subsect. Herrania (Goudot) Colli-Silva, stat. nov. Herrania Goudot, Ann. Sci. Nat., Bot., sér. 3, 2: 230 (1844). TYPE: Herrania albiflora Goudot. Theobroma albiflorum (Goudot) De Wild.
Diagnostic comments. Leaflet margin untoothed, exceptionally partially toothed, veins extending beyond the leaf margin, forming small apicules, <2 mm long; corolla sparsely pubescent, seldom glabrous; petal ligules less then 10× longer than the petal claw. Ten species:
6.3.1. Theobroma albiflorum (Goudot) De Wild., Pl. Trop. Gr. Cult. 90 (1902).
6.3.2. Theobroma balaense (P.Preuss) De Wild., Pl. Trop. Gr. Cult. 89 (1902).
6.3.3. Theobroma breviligulatum (R.E.Schult.) Colli-Silva, comb. nov. Herrania breviligulata R.E.Schult., Caldasia 1(4): 20, figs. s.n. [p. 21], 5 (1942).
6.3.4. Theobroma camargoanum (R.E.Schult.) Ducke, Bol. Técn. Inst. Agron. N. 28: 15, tt. 29, 32 (1954).
6.3.5. Theobroma kofanorum (R.E.Schult.) Colli-Silva, comb. nov. Herrania kofanorum R.E.Schult., Bot. Mus. Leafl. 14(5): 126, tt. 28, 34 (1950).
6.3.6. Theobroma laciniifolium (Goudot ex Triana & Planch.) De Wild., Pl. Trop. Gr. Cult. 90 (“lacinifolium”) (1902).
6.3.7. Theobroma lemniscatum (R.H.Schomb.) Colli-Silva, comb. nov. Lightia lemniscata R.H.Schomb., Rep. Brit. Assoc. Advancem. Sci. 1844(2): 71 (1845). Herrania lemniscata (R.H.Schomb.) R.E.Schult. Caldasia 2(6): 13 (1943).
6.3.8. Theobroma pulcherrimum (Goudot) De Wild., Pl. Trop. Gr. Cult. 89 (1902).
6.3.9. Theobroma purpureum Pittier, Repert. Spec. Nov. Regni Veg. 13: 319 (1914).
6.3.10. Theobroma umbraticum (R.E.Schult.) Colli-Silva, comb. nov. Herrania umbratica R.E.Schult., Caldasia 2(8): 261, t. s.n. [p. 263] (1943).
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Acknowledgments
The authors thank the São Paulo Research Foundation (FAPESP) for their funding support through Grants 2020/01375-1, 2021/08635-1, and 2020/10206-9. Additionally, we would like to acknowledge the assistance provided by Brazil’s Coordination for the Improvement of Higher Education Personnel (CAPES–Financial Code 001), which funded the post-graduate program in which MC-S was enrolled. MC-S extends his gratitude to the International Association for Plant Taxonomy (IAPT) for a grant received. This research was further supported by the UK Research and Innovation (UKRI) Global Challenges Research Fund (GCRF) GROW Colombia grant, administered by the UK Biotechnology and Biological Sciences Research Council (BB/P028098/1), which funded the post-doctoral research of AMB-C. Lastly, we would like to express our deep appreciation to Laurence J. Dorr (Smithsonian Institution) and Douglas C. Daly (New York Botanical Garden) for their meticulous and excellent suggestions that drastically improved the quality of the first version of this manuscript.
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Colli-Silva, M., Richardson, J.E., Bossa-Castro, A.M. et al. Phylogenetic evidence reshapes the taxonomy of Cacao and its allies (Theobroma and Herrania; Malvaceae, Byttnerioideae). Brittonia 76, 53–61 (2024). https://doi.org/10.1007/s12228-024-09783-1
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DOI: https://doi.org/10.1007/s12228-024-09783-1