Ramonadoxa includes one species found in eastern Cuba. This species was formerly included in Chiococca, and it is similar in particular to Chiococca alba. Ramonadoxa plants are slender, glabrous shrubs and small trees with resinous stem apices, petiolate, medium-sized, rather fleshy leaves, persistent rather small stipules that are shortly fused around the stem; axillary, lax, racemiform to sparsely paniculiform inflorescences with small bracts; petiolate, somewhat small, 4-merous flowers; funnelform corollas with thinly imbricate lobes; and fleshy drupaceous fruits with two pyrenes. As in Chiococca, the secondary leaf veins are well developed and visible but the higher-order venation is not evident. Specimens of Ramonadoxa with habitat data report the plants were growing on serpentine substrates; whether all the collections were made in this habitat is not clear, and this aspect of the habitat was not analyzed by Liogier (1962) or Borhidi (2018).

Ramonadoxa is not well known, and no physical specimens have been seen for this present synopsis. Recent published descriptions of this species are generalized and incomplete (Borhidi, 2018; Paudyal et al., 2018), and mostly present similar information to the protologue (Urban, 1921) or Liogier's (1962) description. The pyrenes were not described in the protologue, but have subsequently been described as coriaceous (Liogier, 1962) or woody (Borhidi, 2018; Paudyal et al., 2018). Liogier followed other authors in characterizing the pyrenes of Chiococca as coriaceous, and he included Ramonadoxa in this genus so his description may have been based on extending its characteristics to this species. The description of the pyrenes as "leñosos" by Borhidi (2018: 301) is similar to his use of this term in other Rubiaceae genera to mean "hard", such as the bony pyrenes of Palicourea. The description of the pyenes as "woody" by Paudyal et al. may be only a direct translation of this term, but it may denote a different texture that was not clarified.

The corolla of Ramonadoxa cubensis was described in the protologue as yellow with 4 purple lines on the outside, and in shape as 10-11 mm long, subcylindrical and 3 mm wide when pressed, and narrowed toward the base. A number of specimen labels describe the flowers only as yellow, as reported by Liogier (1962). Borhidi (2018: 301) described the corolla color of this species in two different ways: as yellow with 4 purple lines in the species description, and as brownish red externally and dark yellow internally in the genus description. The first of these corresponds to the protologue description, while the second corresponds to the description of Paudyal et al. (2018: 390), "purple-brown outside, deep yellow inside". Some variation in corolla color is common in Rubiaceae species, and on plants in sunny habitats the corolla not infrequently is flushed with dull purple on the outside. The variation noted in the literature and on specimen labels for Ramonadoxa cubensis would usually be regarded as such variation by many taxonomists, but the specific color and shape of the corolla were regarded as genus characteristics distinguishing Ramonadoxa by Paudyal et al. so their clarification is important here. Paudyal et al. (2018: 389-390) described this corolla as funnelform. gradually expanding towards the mouth", in contrast to the protologue description of subcylindrical. Similarly to corolla color, Borhidi's description of the corolla (2018: 301) agrees with the protologue in his species description, and with Paudyal et al.'s in his genus description. The form of corollas on the type collection corresponds to tubular-funnelform in the terminology here, with the basal third or so of its length flared and the remaining upper portion cylindrical.

Ramonadoxa cubensis was regarded as a species of Chiococca until Paudyal et al.'s (2018) molecular analysis separated several species from that genus. In their analysis, this species was placed on a clade with the Antillean Scolosanthus and the South American Salzmannia, which included two other species they separated from Chiococca. They found the clade with these groups to be sister to Chiococca. Morphologically, Ramonadoxa is similar to Chiococca, and in its formal genus diagnosis Paudyal et al. (2018: 389) noted that they had difficulty finding morphological characters to separate these. They diagnosed Ramonadoxa primarily by its molecular characters and morphological distinctions from Scolosanthus, which is a distinctive spiny genus. They then noted in their diagnosis that they could only separate Ramonadoxa and Chiococca by corolla form and color, "tubular-subcylindrical, purple-brown outside and deep yellow inside" in Ramonadoxa vs. "campanulate to funnelform, white, cream-white to pale yellow throughout" in Chiococca. These corolla forms do appear to differ between the species now included in these genera, although species with both of these corolla forms were included together by them in Coutareopsis in this same study. The differences in corolla color noted by them may be problematic, because different or variant color forms were noted by other authors and documented on the type collection.

Paudyal et al. (2018) also noted that Ramonadoxa was morphologically similar to Salzmannia. They distinguished Salzmannia (2018: 385) by its resinous stem apices (vs. not resinous in Ramonadoxa), subcapitate or shortly racemose inflorescences (vs. cymose), white, yellow, orangish yellow, or green corollas (vs. purple-brown externally and yellow internally), and distribution in South America (vs. Cuba). However, these distinctions were apparently compiled without study of Ramondadoxa specimens, which report the flowers sometimes as only yellow and appear to have resinous stem apices. These distinctions also do not separate Ramonadoxa from Salzmannia naiguatensis, which has similar cymose inflorescences and externally purple-green corollas. Salzmannia is characterized additionally by pink to purple, purple-black, or red fruits, but as noted, the fruit color of Ramonadoxa does not seem to have been documented. Salzmannia naiguatensis was included in that other genus based on the molecular support for its grouping there, but it is not inconceivable that further analysis could find somewhat different support for these branches and Salzmannia naiguatensis to be more closely related to Ramonadoxa than Salzmannia.

Ramonadoxa cubensis is similar to several species of Chiococca. Species of Chiococca differ in their funnelform white to yellow or greenish yellow corollas with longer lobes and their often flattened fruits; the fruits of Ramonadoxa are not well known but appear to be rounded. Ramonadoxa cubensis has been confused with Chiococca alba in herbarium identifications, and by Grisebach (1863) with Chiococca nitida Benth. of northeastern South America. Borhidi (2018) regarded Grisebach's citation as the publication of a new name, but Grisebach explicitly cited Bentham as the author of the name so it was only a misidentification. Paudyal et al. (2018: 390) lectotypified Chiococca cubensis, and they selected a duplicate of the type collection designated by Urban (1921). They regarded Urban's designation as a first-step lectotypification, without explanation; however, Urban identified this collection in the protologue of this name as "typus", so this designation by him is a standard citation of a type and cannot be considered a lectotypification.

Author: C.M. Taylor.
The content of this web page was last revised on 8 April 2021.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

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