Phylogeny and systematics of the tribe Sonerileae (Melastomataceae) in Africa: A revised taxonomic classification

The tribe Sonerileae in tropical Africa and Madagascar is a morphologically diverse lineage that consists of 239 species in 10 genera. In this study, we present the first in‐depth phylogenetic analysis of African Sonerileae to test monophyly of the currently recognized genera. Phylogenetic analyses were performed using sequence data from two nuclear (nrITS and nrETS) and three plastid loci (accD‐psaI, ndhF and psbK‐psbL). Sampling consisted of 140 accessions including 64 African, 27 Malagasy, 46 Asian, and three neotropical Sonerileae together with a broad outgroup sampling (105 spp.). Phylogenetic relationships were inferred using maximum likelihood and Bayesian inference approaches, and a careful reassessment of morphological characters was carried out. Our results neither support the monophyly of the Old World nor African Sonerileae. The monospecific African genus Benna is partially supported as sister to Phainantha, one of the basal neotropical lineages, while African and Malagasy Medinilla are nested among the SE Asian genera. Gravesia (116 spp.), the most species‐rich and morphologically diverse genus in Madagascar, is recovered as monophyletic. The African genera of Sonerileae Calvoa, Dicellandra, and Preussiella form well‐supported clades. In contrast, Amphiblemma (including Amphiblemma molle) and Cincinnobotrys s.l. (including Cincinnobotrys felicis) are not monophyletic. To accommodate the caulescent C. felicis we propose reinstatement of the monospecific genus Bourdaria. For the distinctive A. molle a new genus Mendelia is described. Calvoa hirsuta is designated here as the type of genus Calvoa, lectotypes are designated for Medinilla engleri and Veprecella lutea, and a neotype is designated for Preussiella kamerunensis.

Previous molecular phylogenetic analyses have shown that Bertolonieae are a monophyletic lineage unrelated to the Dissochaeteae-Oxysporeae-Sonerileae complex (Bacci et al., 2019). Bertolonieae s.s. are now treated as a monogeneric tribe (Bertolonia), excluding Monolena Triana ex Hook.f. and Triolena Naudin which are now placed in the Trioleneae. Two other genera, Macrocentrum Hook.f. and Salpinga Mart. ex DC. now belong to Merianieae (Bacci et al., 2019(Bacci et al., , 2020. Kartonegoro et al. (2021) have recently shown that Dissochaeteae are endemic to Southeast Asia and composed of six genera and ca. 90 species. Several molecular studies have supported the monophyly of the Oxysporeae-Sonerileae s.l. complex (including Medinilla and allied genera) (Bacci et al., 2019(Bacci et al., , 2020Zhou et al., 2019Zhou et al., , 2022Kartonegoro et al., 2021). Three neotropical genera, Boyania Wurdack, Phainantha Gleason and Tryssophyton Wurdack are supported as the basal lineages of the Sonerileae-complex (Bacci et al., 2019;Maurin et al., 2021). Nevertheless, these studies sparsely sampled the African and Malagasy endemic members of Sonerileae; it is still not known if the currently recognized genera are natural lineages.
The Oxysporeae-Sonerileae s.l. complex (hereafter the Sonerileae complex) comprises ca. 1079 species in 43 genera, distributed mainly in the Paleotropics (Southeast Asia and Oceania [31 gen./828 spp.], Madagascar [2/184], and Africa [7/ 55]), with a few neotropical entities (6/12) Ulloa Ulloa et al., 2022). It is a morphologically heterogeneous assemblage mainly characterized by apically crowned ovaries, a feature present in two-thirds of the genera (Renner, 1993). They also have angular fruits, a persistent hypanthium and non-cochleate seeds with a tuberculate testa (Triana, 1866). Many Sonerileae are acaulous herbaceous plants with basal rosettes and grow in shaded habitats . Few species have tubers (Cincinnobotrys Gilg and Phyllagathis Blume) and often a basal whorl of large, somewhat turgescent leaves. Anisophylly is also very common in the Sonerileae (Renner, 1993;Fig. 1). Berries and dry capsular fruits from inferior ovaries are also present in the tribe .
The family-wide classification of Renner (1993) recognized the following genera within African Sonerileae: Amphiblemma, Calvoa, Cincinnobotrys (= Gravesiella A.Fern. & R.Fern, Haplophyllophorus A.Fern. & R.Fern. and Primularia Brenan), Dicellandra, Gravesia (= Orthogoneuron Gilg and Neopetalonema), Feliciadamia Bullock (= Adamia Jacq.-Fél.), Ochthocharis (= Phaeoneuron) and Preussiella Gilg. She also transferred Medinilla from Dissochaeteae to Miconieae. Apart from Ochthocharis placed in the Oxyspora alliance, the remaining African and Malagasy genera were treated in the Sonerila-Bertolonia-Gravesia alliance (Renner, 1993). The last classification proposed for the African Sonerileae and Dissochaeteae was by Jacques-Félix (1995). He treated Ochthocharis, Medinilla and Dinophora Benth. in Dissochaeteae and proposed a monogeneric tribe, Feliciadamieae, for Feliciadamia. He retained the rest of the genera in Sonerileae. Dinophora and Ochthocharis are neither part of the Dissochaeteae s.s. nor the Sonerileae complex; they are instead in a polytomy with   Rhexieae, Microlicieae, Marcetieae and Melastomateae. Both of these genera are now placed in a new tribe, Dinophoreae . A summary of these different classification schemes is provided in Table 1. More than 99% of the tropical African species currently treated in Sonerileae are unsampled in molecular phylogenetic studies. Therefore, it is unknown if the African and Asian members of Sonerileae are a natural lineage. In addition, it is unknown whether the currently recognized African Sonerileae genera are monophyletic lineages. As such, the present study seeks to: (i) resolve phylogenetic relationships of the Sonerileae complex using two nuclear (nrETS, nrITS) and three plastid (accD-psaI, ndhF, psbK-psbL) markers, based on a broad sampling; (ii) test monophyly of the currently recognized African genera and (iii) propose a revised generic classification for the African species. A key to all currently accepted African Sonerileae genera is provided. For each previously recognized genus, a diagnosis is provided and a list of accepted taxa. For the newly described genera, a diagnosis, etymology, full description and accepted taxa are provided. Notes are provided to explain lecto-and neotypifications. 2 Material and Methods 2.1 Taxon sampling A total of 245 accessions representing 220 species were included in the phylogenetic analyses to resolve phylogenetic relationships of the Sonerileae complex, with emphasis on the African members. Of the 245 accessions sampled, 91 represent African (64) and Malagasy (27) species. A total of 46 species of Asian Sonerileae and a single species of each of three American Sonerileae genera Boyania, Phainantha and Tryssophyton were also sampled. Except for Feliciadamia which is still unsampled, the rest of the African endemic genera (including type species) currently treated in the Sonerileae complex were sampled (Amphiblemma 12/15, Calvoa 8/19, Cincinnobotrys 4/8, Dicellandra 2/3 and Preussiella 1/2). In addition, 25 Gravesia (including 2/5 African spp. and 23/ 111 Malagasy spp.) and 17 Medinilla species (1/3 African spp., 4/ 73 Malagasy spp., 12/303 Asian spp.) were also sampled.

Phylogenetic inference
Contigs of forward and reverse sequences were assembled and manually edited using SEQUENCHER v.4.1.4 (Gene Codes Corporation, Ann Arbor, MI, USA). Sequences were automatically aligned using MAFFT v.7 (Katoh & Standley, 2013) and then manually adjusted in MESQUITE v.3.10 (Maddison & Maddison, 2016) or MEGA v.11 (Tamura et al., 2021). The best-fit partitioning scheme and models of molecular evolution for the data set were determined using PartitionFinder v.2 (Lanfear et al., 2012(Lanfear et al., , 2017, with the following search parameters: linked branch length; models available in BEAST v.2.5 (Bouckaert et al., 2019), AIC model selection; greedy search algorithm. Each of the five markers was set in the input file as a distinct data block, to avoid overparameterization.

Molecular variation
A total of 4814 aligned characters (1911 parsimonyinformative sites) were used for the analyses. The combined chloroplast data set of all three markers comprised 3164 aligned base pairs while the combined nuclear data set consisted of 1650 aligned base pairs. The selected substitution model for the nrETS, nrITS and ndhF loci was GTR + Γ + I, and for the psbK-psbL and accD-psaI loci was GTR + Γ (Table 2). Additional information and statistics for the data set are provided in Table 2.

Major phylogenetic relationships
The Sonerileae complex is only weakly supported by the ML analyses (Figs. 4A, 4B; BS 59). Excluding the neotropical Boyania which is weakly supported as sister to the remaining members of the Sonerileae complex, the rest of the genera form a well-supported monophyletic clade (  Table 1). Instead, Sonerileae s.l. (including Medinilla and related genera) form a monophyletic lineage. These results are similar to those previously reported (see Bacci et al., 2019;Zhou et al., 2019Zhou et al., , 2022Kartonegoro et al., 2021). Morphologically, Sonerileae s.l. are a very diverse lineage, but most species are characterized by apically crowned ovaries, angular fruits, persistent hypanthia and non-cochleate seeds with a tuberculate testa (Renner, 1993). Although there has been an attempt to resolve phylogenetic relationships within the largely Asian clade (Zhou et al., 2019, an in-depth sampling with better resolution of the Asian lineages is still needed. In addition, the two most diverse genera, Medinilla (~379 spp.) and Sonerila (~184 spp.), are still sparsely sampled with less than 5% of their species included in molecular studies.

African Sonerileae 4.2.1 Benna
Benna is a monospecific genus endemic to Guinea (Burgt et al., 2022). It has large ovate-orbicular alternate leaves and a short paniculate inflorescence appearing somewhat fascicled (Figs. 1A-1E). Together with the neotropical genera sampled, Benna is among the basally diverging lineages and unrelated to the other African or Malagasy genera of Sonerileae (Fig. 4B). It is partially supported (BS 74%) as sister to the South American genus Phainantha.

Gravesia
Gravesia is also rich in species (ca. 116), most of which are endemic to Madagascar with only five endemic species in Africa. It is a morphologically diverse genus of acaulescent or caulescent plants ranging from erect or prostrate herbs to erect shrubs or scandent climbing vines with adventitious roots. The capsule is more-or-less angular and crowned by conspicuous accrescent often slightly woody plates or wedge-like scales. The seeds are oblong to obpyramidal (Perrier de la Bâthie, 1951;Fernandes & Fernandes, 1956;Jacques-Félix, 1983a;Figs. 3U-3Z).
Due to the large morphological diversity of Malagasy Gravesia, three subgenera Eugravesia (Gravesia) (= 100 spp.), Peltivesia H.Perrier (6 spp.) and Amphorovesia H.Perrier (1 sp.) were proposed by Perrier de la Bâthie (1932,1951 In our combined molecular analyses, 25 accessions of Gravesia were sampled (2 from Africa and 23 from Madagascar). Our results recovered both the African and Malagasy Gravesia forming a clade (Fig. 4B). The African Gravesia species sampled are sister to the Malagasy species. With the current limited sampling, we are unable to provide any insights into the infrageneric classification of the Malagasy members.

Bourdaria felicis (Cincinnobotrys felicis)
The genus Bourdaria was described by Chevalier (1932) and distinguished from Cincinnobotrys by the fasciculate flowers and distinctly appendiculate stamens. Bourdaria felicis A.Chev., the only species in this genus, was transferred to Cincinnobotrys by Jacques-Félix (1976) based on its staminal morphology, despite its morphological uniqueness and distribution in West Africa, while all other species of Cincinnobotrys occur in Central and East Africa. Cincinnobotrys felicis is endemic to rocky hills in Guinea and Sierra Leone (a single collection at Kew is from Gbengbe Hills) where it grows in humid crevices on vertical rock (Figs. 2H-2O).
According to Jacques-Félix (1976), unlike the other Cincinnobotrys species in which new plants grow from lateral buds on the tubers or rhizomes, in C. felicis the stem arises vertically from the thickened base which is usually attached to the substrate. During its growing season, a few rosette leaves and sessile, axillary and terminal cymes are produced, so that the stem immediately acquires its final diameter and nodular appearance. Vertical elongation is very slow with an 8-10 cm long stem for a plant nearly 20 years old. Small plantlets may arise from either the base or the top of the tuber as the mother plant approaches senescence. All the same, the stem remains short, and it is this unicaulous characteristic that makes the species unique. Although not very visible, the growth is certainly sympodial, as indicated by the position of the apical flowers (Jacques-Félix, 1976).
Excluding C. felicis, Cincinnobotrys species have a single peduncle with a solitary flower or cymose inflorescence. In C. felicis, the inflorescences are axillary fascicles with one to several flowers borne on long and slender pedicels (Figs. 2H-2O). Like most Cincinnobotrys species [except for C. acaulis (Cogn.) Gilg and C. pulchellus (Brenan) Jacq.-Fél. with pentamerous flowers], C. felicis has tetramerous flowers (Jacques-Félix, 1976). In C. felicis the ovary is adherent to the hypanthium for its entire length with the calyx lobes peripherally accrescent and the placentas clearly displaced on the apex. The crown forms acute margins from the concave ovary. The fruits are tetragonal, marked with four calyx ribs and four weaker intermediates. The seeds are 0.5 mm long, with a slender and fragile funicle, obovoid, asymmetric, and finely tuberculate (Jacques-Félix, 1976).
In our molecular analyses, C. felicis is excluded from Cincinnobotrys s.s. and instead recovered as sister to a clade consisting of Dicellandra, Calvoa, Preussiella, Amphiblemma and Cincinnobotrys s.s. (Fig. 4B). Together with its unique morphology and geographical distribution, our molecular analyses support reinstating the monospecific genus Bourdaria.

Dicellandra
Dicellandra was described by Hooker (1867), but over the decades its species composition grew doubtful (Jacques-Félix, 1974a). A total of ten species have been described in Dicellandra with only three species currently accepted [D.
In our molecular analyses, we included six accessions representing two Dicellandra species (D. barteri and D. descoingsii). We recovered Dicellandra as a monophyletic lineage and sister to a clade consisting of Calvoa, Preussiella, Amphiblemma and Cincinnobotrys s.s. (Fig. 4B). Dicellandra was treated in Dissochaeteae (Medinilleae) by several authors based on its irregular capsule dehiscence and wedged-shaped seeds (Hooker, 1867;Triana, 1872;Cogniaux, 1891;Gilg, 1898;Engler, 1921;Jacques-Félix, 1955). In the revision of Dicellandra and later taxonomic treatments, it was treated in Sonerileae (Jacques-Félix, 1974a, 1983a, 1983b. Our molecular results support the inclusion of Dicellandra in Sonerileae. Dicellandra barteri is widespread in the Guinean-Congolian region from Cameroon to Liberia. Dicellandra barteri var. magnifica is found almost throughout the eastern DR Congo to Kivu and Uganda but also in Mayombe. The other varieties have narrower distributions. Dicellandra barteri var. erecta is restricted to the southern region of Cameroon and the Biafran region while var. escherichii extends from southern Cameroon to the mouth of the Congo. Dicellandra glanduligera and D. descoingsii are only known from a few sites in the Ngounié basin in Gabon. Jacques-Félix (1974a) suggested that Dicellandra are humicoles and either hygro-sciaphilous or hemisaprophytes. However, this interesting phenomenon is still being monitored in the field.
We included 20 accessions of Calvoa representing nine species in our molecular analyses. All these accessions formed a monophyletic lineage sister to a large clade composed of Amphiblemma molle Hook.f., Preussiella, Cincinnobotrys and Amphiblemma s.s. (excluding A. molle). Calvoa is a morphologically well-defined genus supported by molecular data (Fig. 4B), but its species limits are nevertheless still poorly known. Several species, for example, C. monticola, C. pulcherrima and C. orientalis are not monophyletic (Fig. 4B). The 19 accepted species of Calvoa are mainly distributed in West-Central Africa (from Sierra Leone to Angola, through Central Africa) and in the four islands of the Gulf of Guinea (Annobon, Bioko, São Tomé, and Príncipe). Only the widespread C. orientalis extends to East Africa (Ethiopia, Rwanda, Tanzania and Uganda).

Amphiblemma
The genus Amphiblemma was first described by Naudin (1851) -Félix, 1973-Félix, , 1974b-Félix, , 1987Leal, 2008). This shade-tolerant genus is restricted to forest and gallery forest of Central Africa with its highest diversity and endemism in Gabon (10 spp.) and Cameroon (6 spp.). Engler (1921) proposed the first infrageneric classification of Amphiblemma and recognized three sections: sect. Cincinnatae Engl., sect. Corymbosae Engl., and sect. Axillares Engl. Later, Brenan (1953) proposed an additional section, Amphiblemma sect. Haplophyllophora Brenan. He distinguished this section from sect. Amphiblemma as follows: acaulous species, which usually have one or rarely two leaves per plant with the leaves and inflorescences arising directly from the rootstock or tuber (Brenan, 1953). On the other hand, Amphiblemma is composed of species with elongate stems bearing pairs of leaves separated by internodes, stems not enlarged and rooting laterally (Brenan, 1953). He transferred two species previously treated in Cincinnobotrys [C. acaulis (Cogn.) Gilg and C. seretii De Wild.] to sect. Haplophyllophora. Only the sect. Cincinnatae and sect. Corymbosae were accepted by Jacques-Félix (1973).
In this study, we sampled 22 accessions representing 12 species of Amphiblemma. Our results show that Amphiblemma is not monophyletic since one species, A. molle, is recovered outside of the Amphiblemma s.s. lineage (Fig. 4B). Excluding A. molle, a morphologically unique species and the lone species in sect. Cincinnatae, the remaining species of Amphiblemma (treated in sect. Corymbosae) are morphologically well characterized. Unlike the species in sect. Corymbosae, A. molle is characterized by solitary, erect, elongated, uniparous cymes with many flowers, sepals with a linear subapical appendage and an epigynous crown protruding at maturity. The species of sect. Corymbosae have uniparous cymes with two to five digitate branches forming a corymb or sometimes panicles. The cymes are at times reduced or pauciflorous, forming a contracted umbel or sometimes axillary cymes. The sepals lack linear appendages, and the epigynous crown is included (Figs. 1F-1Q).
Amphiblemma as treated here consists of 14 species mainly distributed in the Congolian region with only one species, A. cymosum, extending to the Guinean region. Morphological and molecular evidence suggest excluding A. molle from Amphiblemma.

Mendelia mollis (Amphiblemma molle)
Amphiblemma molle was described by Hooker (1871). Although its inflorescence would suggest that it belongs to Amphiblemma sect. Cincinnatae, Engler (1921) treated this species in Amphiblemma sect. Corymbosae on the basis of its leaves. He placed two species (A. erythropodum Gilg & Lederm. and A. riparium Gilg) from Cameroon in sect. Cincinnatae. Jacques-Félix (1973) in his revision of Amphiblemma treated A. riparium as a synonym of A. molle while he was unable to identify A. erythropodum and suggested it might be another synonym. He treated A. molle as the lone species in sect Cincinnatae. The type specimen of A. erythropodum was destroyed in Berlin during World War II.
In addition to its erect, elongated, uniparous cymes bearing alternate subsessile flowers, the mucronate sepal tip in A. molle develops into distinct linear appendages ( Figs. 2A-2G). Also, the corolla is clearly reduced and inconspicuous. Most Amphiblemma species have capsules with loculicidal dehiscence via valves: the tip splits along the five valves dividing the epigynous crown into many segments. In the case of A. molle, the placentas separate from the axis and extend somewhat to the tip. The reduplicated membranous crown does not split over its entire length but opens in a star around the five branches of the placenta.
Based on morphological uniqueness and our molecular phylogenetic results (see Figs

Cincinnobotrys
Cincinnobotrys was described by Gilg (1898) as a monospecific genus based on C. oreophilus, an epiphytic acaulescent species with a bulbil-bearing rhizome, roots forming tubers, solitary leaves and tetramerous flowers. Gilg (1898) retained A. acaule Cogn. in Amphiblemma even though this species morphologically resembles C. oreophilus, differing from it only by having pentamerous flowers. The second species of Cincinnobotrys, C. seretii De Wild., was described by De Wildeman (1908) as very close to A. acaule.
Cincinnobotrys s.s. are acaulescent perennial herbs with one or two leaves and inflorescences arising from a bulbilbearing rhizome (Figs. 3H-3K). They are epiphytes or epiliths that attach to their substrates using rhizomes, tubers or more rarely by a small napiform stump supporting an erect stem. Apart from C. felicis, the species usually have one cyme and one leaf (rarely two or more), with further growth emerging only from axillary buds. In Cincinnobotrys s.s., the lateral bud at the base of the leafyflowering internode is also likely to produce a lateral branch. These species therefore have the ability to propagate and disperse vegetatively. Several collectors have reported them as being very abundant in their habitats (Jacques-Félix, 1976).
Anisophylly is also well-developed in Cincinnobotrys s.s., with a strong size reduction in one of the two leaves. The flowers are always small, except for the corolla which is sometimes well-developed. The receptacle is largely campanulate, turbinate or rarely urceolate. The petals are widely inserted and often asymmetrical. Except for C. acaulis with regularly pentamerous and C. pulchellus with tetra-or pentamerous flowers in the same small population, the rest of the species are tetramerous. Cincinnobotrys s.s. have either four (haplostemonous) equal, or eight (diplostemonous) dimorphic stamens in two whorls with well-developed appendages. The ovary has four or five locules that adhere to hypanthium/ receptacle nearly to the top, which is apically depressed with a narrow glandular-ciliate crown or conspicuous scales. The seeds are generally obcuneate with or without a minute papillate testa (Jacques-Félix, 1976).
For the molecular analyses, we sampled six accessions representing the following Cincinnobotrys s.l.: C. acaulis [=Haplophyllophorus acaulis (Cogn.) A.Fern. & R.Fern], C. felicis (=Bourdaria felicis), C. oreophilus (type species)] and C. ranarum Pócs. Excluding C. felicis, Cincinnobotrys is resolved as a monophyletic clade but in a polytomy with Preussiella and Amphiblemma s.s. (Fig. 4B) As here defined, Cincinnobotrys s.s. (excluding C. felicis) consists of seven species mainly distributed in the Zambezian region with three species extending to the Congolian region. Tanzania seems to be the centre of diversity of Cincinnobotrys s.s., with five of the seven species occurring there, two of them being endemic.

Preussiella
Preussiella are glabrous epiphytic shrubs, with thick and swollen nodes. Anisophylly is present in Preussiella although not very pronounced. Inflorescences are large terminal or apical uniparous cymes. The lax inflorescence of Preussiella is similar to those of Dicellandra barteri var. magnifica but have an opposite-decussate branching pattern. Preussiella flowers are pentamerous, large and colorful. The hypanthium is narrowly obconical. The stamens are diplostemonous, isomorphic to sub-equal. The fruit is ellipsoid-oblong (Jacques-Félix, 1974a, Figs. 3L-3O).
The two species in this genus, P. kamerunensis Gilg and P. gabonensis Jacq.-Fél. are mainly differentiated by the leaf shape, attachment and venation. The leaves of P. kamerunensis are oval to ovate-lanceolate with two pairs of acrodromous veins and long petioles. In P. gabonensis the leaves are elliptic, subsessile with one pair of acrodromous veins. These epiphytic species are restricted to the Guinean-Congolian region with their primary substrate being tree trunks. The widespread P. kamerunensis is found in Guinea and extends to Gabon and DR Congo while P. gabonensis is endemic to Gabon. Preussiella kamerunensis is the only member of African Melastomataceae with a chromosome number of n = 22 (Favarger, 1952(Favarger, , 1962Farron & Favarger, 1983). The chromosome number of P. gabonensis is still unknown.
We included four accessions of P. kamerunensis in our molecular analyses. These formed a well-supported monophyletic clade, but in a polytomy with Cincinnobotrys s.s. and Amphiblemma s.s. (Fig. 4B). Morphologically, Preussiella is a very distinct genus and can be clearly separated from the other Sonerileae genera. Our molecular results support the treatment of Preussiella in Sonerileae as was done by Jacques-Félix (1977), not in Dissochaeteae (see Gilg, 1898;Engler, 1921).

Taxonomic Treatment
In this section, we focus on the African Sonerileae. All 10 currently accepted genera have been sampled in the molecular phylogeny and in combination with morphology, we here provide an updated classification at the generic rank. The monospecific genus Bourdaria is reinstated, and a new monospecific genus Mendelia is described. To complete the realignment of the African Sonerileae, three lecto-or neotypes are designated. We also provide a key to the 10 African genera of Sonerileae. Morphological diagnosis: Mostly terrestrial perennial herbs and shrubs with glandular hairs very frequent on the floral organs; flowers pentamerous; stamens dimorphic; ovary inferior to semi-inferior, with an epigynous crown with five lobes; fruit dehiscence valvate. Amphiblemma differs from Mendelia by the following characters: cymes with two to five digitate branches forming a corymb, panicle, contracted umbel or sometimes axillary cymes (vs solitary, erect, elongated, uniparous cymes with many flowers); sepals lack linear appendages, and the epigynous crown is included (vs sepals with a linear subapical appendage and an epigynous crown protruding at maturity). See also Figs. 1F-1Q.
Note: Engler (1921) described Amphiblemma mildbraedii from Bioko (historically Fernando Po) in the northernmost part of Equatorial Guinea, "bei Musota oberhalb San Carlos (a. d. Westküste) in niedrigem Wald um 600-1200 m," but he did not cite a collector or collection number. Like most of the other melastome types that he designated, these were destroyed in Berlin during WW II. However, there is a collection by J. Mildbraed 705 in Hamburg (HBG), HBG509099 matching the locality described by Engler (1921). It seems likely that the specific epithet was in honor of the collector, J. Mildbraed. We therefore suspect that the material housed in HBG (HBG509099!) is an isotype. Morphological diagnosis: Benna can be morphologically identified by the following combination of characters: it is a herb with alternate leaves, margins dentate; inflorescence cymose, paniculate, axillary, branching alternate; flowers actinomorphic, 4-merous, stamens 8, dimorphic; fruit a capsule, apically dehiscent, numerous seeds; seeds obovoid or nearly so, glossy, testa smooth. Benna differs from all other African Melastomataceae genera by the following: Leaves alternate (vs opposite or whorled); seeds obovoid or nearly so, glossy, testa smooth (vs seeds diverse but not as in Morphological diagnosis: Bourdaria differs from all other African Sonerileae by its short vertically rising stems that arise from a tuberous or cormose base; plant usually not epiphytic; flowers tetramerous, borne in axillary fascicles with one to several flowers on long slender pedicels; seeds small with a slender and fragile funicle, obovoid, asymmetric, and finely tuberculate. Bourdaria differs from Cincinnobotrys by having a short stem (vs acaulous); leaves 2-6 in rosettes (vs leaves 1-few, broadly ovate-cordate, petioles long and borne directly from the base); capsule distinctly tetragonal (vs capsule turbinate or campanulate but distinctly-ribbed).
Accepted Note: Gilg (1897) described Cincinnobotrys oreophilus from Tanzania, Uluguru Mts, Mt Nglewenu, based on the collection Stuhlmann 8804 housed in Berlin and destroyed during WW II. However, a leaf fragment and illustration from the collection is at BR and designated Typus with no specification of the type. We therefore interpret this collection at BR to be an isotype (BR0000006260330!).
Morphological diagnosis: Robust erect or creeping, ascending to leaning single-stemmed perennial herbs or shrubs with a unicaulous or sympodial branching habit, epiphytic, rooting along the nodes; inflorescences multiflowered thyrses; flowers pentamerous, calyx and corolla short, already well exposed before anthesis; hypanthium glabrous or densely furfuraceous. The stamens are either dimorphic or isomorphic but with two anterior appendages or one posterior appendage. Ovary 5-locular, inferior, apex concave with an epigynous membranous crown; style linear, though somewhat thickened toward the top, often bearing glandular tannic hairs toward the base; stigma punctiform to subcapitate. Capsules ellipsoid-oblong to globular and remaining enveloped by the hypanthium and persistent calyx, seeds obconical, with an aril or raphe forming a lateral spur at the tip, dehiscence irregular. Dicellandra differs from Amphiblemma by the following characters: hypanthium glabrous or densely furfuraceous (vs hypanthium pubescence variable but mostly with glandular hairs); capsule ellipsoid; seeds obconical, with a raphe forming a lateral spur at the tip, dehiscence irregular (vs capsule, obconical, crateriform, campanulate, dehiscence valvate). See also Figs. 3A-3G.
Note: Gilg (1904) described Medinilla engleri from Tanzania, Lushoto District, Amani based on the following syntypes: Engler 570 & Warnecke in Herb. Amani 387. All the collections housed in B were destroyed during WW II. However, there is a duplicate of Warnecke at EA (cited by Wickens, 1975). We therefore designate this collection as the lectotype. Medinilla engleri Gilg, Bot. Jahrb. Syst. [Engler]  Morphological diagnosis: Mendelia are perennial herbs with erect, elongated, uniparous cymes; the mucronate sepal tip develops into distinct linear appendages. Mendelia differs from Amphiblemma by the following characters: solitary, erect, elongated, uniparous cymes with many flowers (vs cymes with two to five digitate branches forming a corymb, panicle, contracted umbel or sometimes axillary cymes); sepals with a linear subapical appendage and an epigynous crown protruding at maturity (vs the sepals lacking linear appendages, and the epigynous crown is included).
Etymology: In 2022 is the bicentennial birthday of Gregor Johann Mendel. The generic name Mendelia is a feminine noun, proposed in his honor.
Description: Perennial herbs or subshrubs, erect, branched, hairy to velutinous in all parts, often reddish in color, twigs slender, subangular or terete, covered with dense bristles or capitate hairs; two protuberant interfoliar lenticels present on each node. Leaves opposite, petiolate, slender, densely velutinous; lamina ovate, base rounded to cordate, apex acuminate to acute, appressed setose hairs on both sides, margins obscurely dentate-ciliate. Flowers white to pink, pentamerous (rarely hexamerous), shortly pedicellate, in solitary or terminal uniparous cymes, shortly penduculate bearing up to 50 biseriate flowers (opposite because of sympodial growth) borne on a densely velutinous rachis. Hypanthium covered with velutinous hairs, ovoidcampanulate; sepals triangular to obtuse, with a linearsubulate appendage on the back, hirsute. Petals pink, rarely white, oblong, apex with setose or capitate hairs. Stamens 10, dimorphic, antesepalous stamens with relatively short pedoconnectives, poorly arched, prolonged ventrally with an obtuse-emarginate appendage and dorsal appendage absent, antepetalous stamens with connective not extended at base into a pedoconnective but ventrally bilobed and dorsal appendage short. Ovary adnate to the calyx for most of its length, forming a free crateriform cavity, cylindrical reaching the hypanthium rim and an epigynous crown. Fruit campanulate, ovary protruding out of the receptacle (convex) and sepals by the veined crowns, pentagonalreduplicate, margins ciliate, truncate to wavy; dehiscence valvate. Seeds minute and papillose. See also Figs Morphological diagnosis: Epiphytic (sometimes epilithic) shrubs, glabrous, stems subquadrangular, thick and swollen at the nodes, bark more-or-less corky; leaves large with slender petioles, blades ovate to ovate-lanceolate. Inflorescences axillary or terminal thyrses bearing many flowers; flowers pentamerous, large and colorful; hypanthium narrow to obconical and progressively connected to the pedicel; calyx short, lobes indistinct; stamens 10, dimorphic or isomorphic, pedoconnectives with an anterior appendage, dorsal appendages conspicuous; ovary adnate to the calyx at the apex, with no crown; fruit oblong-ellipsoid, weakly pentagonal, 5 (-10)-ribbed; capsule dehiscence loculicidal or septicidal; placentas sessile over the entire length of the locules having five to six rows of seeds. The seeds are numerous, perpendicular to the axis, appendiculate at the base by the lamellate funicle, and at the apex by the lamellate-truncated expansion of the tegument; the seed itself is reduced, oblong, and finely papillose. Preussiella differs from Amphiblemma by the following characters: epiphytic (sometimes epilithic) shrubs more or less glandular (vs mostly terrestrial perennial herbs and shrubs with glandular hairs frequent on the floral organs); calyx lobes conspicuous or minute (vs calyx lobes conspicuous); ovary adnate to the calyx at the apex, with no crown produced (vs ovary adnate to the calyx at the apex with a crown produced); capsule oblong-ellipsoid, weakly pentagonal, 5 (-10)-ribbed, dehiscence loculicidal or septicidal (vs capsule obconical, crateriform, campanulate, dehiscence valvate). See also Figs. 3L-3O.
Note: Gilg (1898) described Preussiella kamerunensis and designated a specimen from Cameroon, Barombi-station collected by Preuss 442 as the type. This collection was housed in Berlin and destroyed during WW II. There is no trace of this specimen with no known duplicates. We thus designate a neotype, collected in Cameroon and housed in WAG together with two isoneotypes in WAG and BR, respectively. Preussiella kamerunensis Gilg in Monogr. Afrik. Pflanzen-Fam. [Engler]

Supplementary Material
The following supplementary material is available online for this article at http://onlinelibrary.wiley.com/doi/10.1111/jse. 12921/suppinfo: Fig. S1. Bayesian inference phylogeny of African Sonerileae based on the nuclear matrix (nrITS, nrETS). Values at the nodes refer to posterior probabilities. Fig. S2. Bayesian inference phylogeny of African Sonerileae based on the plastid matrix (accD-psaI, ndhF, psbK-psbL). Values at the nodes refer to posterior probabilities. Fig. S3. Maximum likelihood phylogeny of African Sonerileae based on the plastid matrix (accD-psaI, ndhF, psbK-psbL). Values at the nodes refer to posterior probabilities. Fig. S4. Maximum likelihood phylogeny of African Sonerileae based on the nuclear matrix (nrITS, nrETS). Values at the nodes refer to posterior probabilities.