Coutarea is characterized by its woody habit; lack of raphide crystals in the tissues; opposite leaves; interpetiolar, triangular, generally persistent stipules; terminal, bracteate, cymose, generally few-flowered inflorescences; bisexual, homostylous, generally rather large flowers with 5 to 7 calyx lobes, corolla lobes, and stamens; tubular to broadly funnelform, actinomorphic to weakly zygomorphic corollas with the lobes thinly imbricated in bud; stamens inserted near the base of the corolla and arranged all together on the lower side of the flower due to the twisting of the long filaments; a cylindrical stigma borne on a long style; ovary with 2 locules and numerous ovules in each locule on axile placentas; woody capsules that are generally elliptic to orbicular in outline, strongly flattened perpendicular to the septum, and septicidal from the apex; and numerous flattened, generally orbicular seeds with a concentric marginal wing. The corollas are generally showy and variously white to pink or flushed with purple.Their form suggests they may be adapted to bat pollination, and perhaps nocturnal. Because the flowers sometimes have a slightly zygomorphic corolla, usually 6 lobes, and the anthers arranged all on one side, Coutarea is sometimes not recognized as a species of Rubiaceae. The capsules that are flattened perpendicular to the septum are distinctive. This genus usually is found in rather dry seasonal vegetation, but Coutarea hexandra sometimes ranges into fairly wet vegation.

The corolla of Coutarea is weakly plicate in bud, with the folded sinuses extruded and also the contact zones of the lobes compressed to form wings on the corolla bud (e.g., Stevens 40100). Aieillo detailed the ovary arrangement of Coutarea (1979: 69, figs. 61, 62). She described the ovary arrangement as "linear placentae.... The seeds... are oriented vertically... there are about 50 per capsule". She characterized the dehiscence of the capsule as shortly loculicidal then septicidal (Table 7), but on the specimens seen it appears to be the opposite, or if the first line of dehiscence really is loculidal it is only very short, then more opening proceeds loculicideally only after the septum separates (e.g., Lorence et al. 2012; Taylor 9734).

Coutarea is related to a group of genera whose relationships have been poorly understood, but are now better clarified. Molecular systematic studies first identified this group but provided little information about relatioinships within it, and this was regarded for some time as the rather intractable "Catesbeeae-Chiococceae-Exostema Complex (Robbrecht & Manen 2006, p. 116). More recently Paudyal et al. (2018) analyzed this group in more detail with more molecular data, and they included most of these genera in a revised Chiococceae. Coutarea was known for some time to be problematic systematically, in both the circumscription of the genus to include several morphologically differing species from interAndean high valleys (McDowell & Bremer, 1998; Taylor & Lorence, 2010), and the circumscription of Coutarea hexandra. Paudyal sampled one of the two species that had been considered "core" Coutarea, and found it placed on a clade together with the monotypic Adolphoduckea. They found this clade placed sister to another clade comprising the two anomalous species of Coutarea and a species of Exostema that was suggested to be related to them, and they found these two sister clades to form a monophyletic group that was sister to a clade comprising Exostema and Solenandra; their results included more taxa, but were generally similar to those of McDowell & Bremer. Overall, the taxonomy of Paudyal et al. emphasized differences between the taxa they sampled, and they separated all four of these lineages into species with one, two, or three species rather than treating the entire clade as Coutarea. The plants separated as Adolphoduckea differ strikingly in some morphological features, but all of these share many feature with each other also.

Even more recently, Greuter & Rankin-Rodríguez (2021) reviewed the systematics of this group again, using the analysis previously published by Paudyal et al. (2018), and reached a different conclusion. They recognized one broadly circumscribed genus that comprised what Paudyal et al. separated as Exostema, Solenandra, Hintonia, several newly segregated genera, and Coutarea. Based on their view of this group as centered in Cuba and Exostema caribaeum as its presumed most well known species, Greuter & Rankin-Rodríguez (2021) proposed conservation of the name Exostema over the oldest name, Coutarea, for this entire group. However, Coutarea hexandra is much more widely distributed naturally and in cultivation, and this genus could be argued as a better name for this group is expanded in this new circumscription. If Exostema is eventually conserved against Coutarea, it will only have priority when these two genera are combined; when Paudyal et al.'s taxonomy is used, Coutarea and Exostema are separated so the conservation is not applicable. Delprete & Paudyal (2023) responded to this new circumscription in print with a review and re-justification for their own taxonomic views.  

Coutarea was studied in detail by Ochoterena-Booth (1994, 2000), who recognized three species: Coutarea alba, Coutarea hexandra, and Coutarea andrei; this last was separated by Paudyal et al. (2018) into Coutareopsis. Not authors have separated Coutarea alba (e.g., Bacigalupo et al., 2008), but these appear to be distinct at least in some regions (Taylor et al., 2004). Coutarea hexandra is widespread and variable morphologically, and also shows a range of habitats from quite dry to quite wet. Plants of this species also vary notably in leaf and flower size within local areas (Lorence et al., 2012), which is a common feature of plants in habitats with variation in water availability and plants with nocturnal flowers. Coutarea is in need of study with field observations and phylogeographic tecniques, and it is not unlikely that both of its species will be found to comprise several allopatric lineages and perhaps distinct species.

Coutarea is similar to Coutareopsis, which can be separated by its smaller corollas that are actinomorphic at anthesis, included anthers, and habitat at higher elevations, 1900-2800 m. Motleyothamnus and Adolphoduckea can be separated by their salverform corollas with the narrow lobes about as long as the tube.Coutarea is also similar to Exostema and Solenandra, and these can be easily confused without flowers. Exostema and Solenandra in general can be separated by their capsules that are not flattened, corollas that are salverform with a generally very narrow cylindrical tube, and stamens that are positioned symmetrically, and anthers exserted on well developed filaments; in contrast, Coutarea has flattened capsules, corollas that are tubular to funnelform with the tube moderately to very broad, stamens usually arranged all one side of the flower, and anthers included to shortly exserted. Coutarea is also similar are Coutaportla, Lorencea, and Hintonia of Mexico and Central America. Coutaportla can be separated from Coutarea but its fewer seeds, ca. 2-5 per locule, and its flowers with 5-merous flowers; Lorencea can be separated by its fewer seeds on basal placentas and 4-5-merous flowers; Hintonia can be separated by its caducous stipules, solitary flowers, and capsules that are not flattened.

Author: C.M. Taylor.
The content of this web page was last revised on 8 July 2024.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

• Taylor, C. M. & D. H. Lorence. 2010. Rubiacearum americanarum magna hama pars XXII: Notable new species of South American Coutarea, Morinda, Patima, and Rosenbergiodendron. Novon 20(1): 95–105.
• Ochoterena-Booth, H. 1994. Revisión taxonómica del género Coutarea Aublet (Rubiaceae). 1–100. In H. Ochoterena-Booth Rev. Tax. Coutarea. Tesis MS, Universidad Nacional Autónoma de México, México.
• Robbrecht, E. & J. F. Manen. 2006. The major evolutionary lineages of the coffee family (Rubiaceae, angiosperms). Combined analysis (nDNA and cpDNA) to inferthe position of Coptosapelta and Luculia, and supertree construction based on rbcL, rps16, trnL-trnF and atpB-rbcL data. A new classification in two subfamilies, Cinchonoideae and Rubioideae. Syst. & Geogr. Pl. 76: 85–146.
• Paudyal, S.K., P. G. Delprete, S. Neupane & T. J. Motley. 2018. Molecular phylogenetic analysis ad generic delimitations in tribe Chioccceae (Cinchonoideae, Rubiaceae). Bot. J. Linn. Soc. 187: 365-396.
• Ochoterena-Booth, H. 2000. Syst. Hintonia Portlandia Complex i–xv, 1–289. Unpublished Ph.D. dissertation, Cornell University, Ithaca.
• Greuter, W.R. & R. Rankin Rodríguez. 2021. Notes on the genus Exostema (Rubiaceae), its limits and sectional subdivision. Taxon (12603): 1-6.
• Greuter, W.R. & R. Rankin Rodríguez. 2021. (2831) Proposal to conserve the name Exostema against Coutarea (Rubiaceae). Taxon 70(4): 906.
• Delprete, P. G. & S.K. Paudyal. 2023. Rebuttal to Greuter & Rankin-Rodríguez's (2831) proposal to conserve Exostema against Coutarea (Rubiaceae) and to their expanded circumscription of Exostema. Taxon 72(5): 1098–1108.