Tropicos | Name - Donnellyanthus Borhidi

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Donnellyanthus Borhidi

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Project Name Data (Last Modified On 7/2/2021)

Acceptance : Accepted

Note : Tribe Rondeletieae

Project Data (Last Modified On 8/9/2021)

Notes :

Donnellyanthus includes 1 species of slender shrubs and small trees, which are characterized by well developed main stems bearing short lateral stems; medium-sized to rather small, thin-textured leaves with pubescent domatia, short, triangular, interpetiolar stipules that enclose a ring of well developed strigose pubescence; flowers boen on the short lateral stems, singly in the leaf axils and also in fasciculate to shortly cymose groups of 3--5 at the stem apices; medium-sized, usually orange to pink or red, 4-merous, salverform flowers; rather small, subglobose, loculicidal capsules; and somewhat small, flattened seeds with irregular but usually circumferential wings. The leaves and flowers are produced on lateral, often rather short stems. These lateral stems arise from nodes from which the leaves have fallen, but are distinctive in having the basal portion of the dehisced petiole 1-1.5 mm long and markedly thickened. The flowers are distylous. Borhidi et al. (2011) described the corollas as white or pink, but they are described on specimens as red, pink, pinkish orange, orange, and yellow on most specimens, and white on one specimen (Coronado & Soriano 601). The corollas are papillose to puberulous with thickened protuberances or trichomes in the throat and on the bases of the lobes,. They lack a thickened ring in the corolla throat, but the throat area of the corolla appears on specimens to be somewhat swollen or stretched in this area so some flowers can appear to have some sort of ringed structure here. The corolla mouth does not appear to be differently color from the rest of the corolla. The pollen morphology was detailed by Torres-Montúfar et al. (2020). Lorence et al. (2012) described the seeds as fusiform-elliptic and winged on both ends, but these are better characterized as elliptic-angled with a marginal wing that is often wider on one or two sides. Donnellyanthus deamii is rather commonly collected.

Donnellyanthus was first recognized as distinct from Rondeletia (and Arachnothryx) by Borhidi et al. (2011) based on morphological features of the corolla and seeds that demonstrated it to be distinct from Rondeletia. The testa ornamentation of Donnellyanthus was compared with several species of Rondeletia, but without a comprehensive review of that genus. This single species of Donnellyanthus was also included by Borhidi at one time in Arachnothryx, but its clssification there and its separation from that genus were not noted or explained by Borhidi et al. Lorence et al. (2012) included Donnellyanthus deamii in Arachnothryx provisionally, with a note that it did not agree morphologicially with either that genus or Rondeletia but that this entire group was not well enough understood to postulate a different placement.

Donnellyanthus's single species was found by Torres-Montúfar et al. (2020) to be a distinct lineage of Rondeletieae based molecular sequence data. They concluded (Torres-Montúfar et al., 2021) that lineages in this group are characterized by particular details of the form and pubescence of the corolla, which is not the case in many other Rubiaceae groups, but did not characterize or examine Donnellyanthus in detail. They appear to have presented the first molecular data for this species. They noted that it is similar to Arachnothryx morphologically, and that Arachnothryx is not fully studied and until those species are all known, it is not possible to conclude that Donnellyanthus is monotypic.

Donnellyanthus is similar to some species of Rondeletia as noted by Borhidi et al. (2011). They noted that Rondeletia differs in its corollas with a thickened ring in the throat, as well as by its pubescent disc and style with pubescence in the basal portion, and seeds arranged horizontally on the placenta, oblong, and fusiform to bialate (i.e., bicaudate), vs.in Donnellyanthus a glabrous disc and style, and seeds arranged vertically on the placenta and elliptic with a circumferential wing. Borhidi et al. also illustrated the testa of Donnellyanthus as reticulated with numerous rounded foveolate within each section, vs. in 6 species of Rondeletia surveyed with the testa variously reticulated with variously obtuse protuberances, narrow foveolae, and numerous rounded foveolae. The seeds of some Rondeletia species (e.g., Rondeletia belizensis) are vertically arranged on the placenta, and angular-discoid and not markedly dissimilar in shape to those of Donnellyanthus in shape but they do lack a marginal wing.

Donnellyanthus was not found to be closely related to Tainus by Torres-Montúfar et al. (2020), but these are generally quite similar in aspect and a number of morphological details. Tainus is found in Hispaniola, and differs from Donnellyanthus in its 5-merous flowers, white to yellow corollas with the mouth differently colored from the rest of the corolla.

Author: C.M. Taylor. The content of this web page was last revised on 6 July 2021.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/ta30or.shtml

Distribution :

Humid to semi-deciduous vegetation, 100-1300 m, southern Mexico (Chiapas, Oaxaca) to central Central America (Guatemala, El Salvador, Honduras, Nicaragua). This species has been quite commonly collected in Nicaragua. The distribution in Chiapas was cited by Lorence et al. (2012), but overlooked by Borhidi et al. (2011) and Borhidi (2012).

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Shrubs and small trees, unarmed, terrestrial, without raphides in the tissues, rather slender. Leaves opposite, petiolate, entire, with the higher-order venation not lineolate, with pubescent domatia; stipules interpetiolar, triangular, cuspidate, erect, perhaps imbricated in bud, tardily deciduous, adaxially enclosing a ring of well developed sericeous pubescence. Inflorescences borne on short lateral shoots, one-flowered and axillary and also several--flowered, terminal, and fasciculate to shortly cymose, pedunculate, ebracteate or with some foliaceous bracts. Flowers pedicellate, bisexual, distylous, protandrous, perhaps fragrant, perhaps diurnal; hypanthium ellipsoid to obovoid; calyx limb developed, deeply 4(--6)-lobed, without calycophylls but with lobes usually unequal on an individual flower; corolla salverform, yellow to pink, pinkish orange, deep red, or rarely white, medium-sized (9--14 mm long), internally glabrous in tube and puberulous at mouth, lobes 4, ligulate to elliptic, in bud imbricated, spreading to weakly reflexed at anthesis, without appendage but with margins sometimes weakly crisped; stamens 4, inserted in upper part of corolla tube, anthers narrowly oblong, dorsfiixed near base, dehiscent by linear slits, included to partially exserted depending on morph, without appendage at top; ovary 2-locular, with ovules numerous in each locule, on axile placentas, stigmas 2, ellipsoid to linear, included or exserted depending on morph. Fruit capsular, subglobose, loculicidally dehiscent from apex, with valves perhaps remaining fused at base, rather small (3.5--5 mm long), chartaceous to woody, weakly didymous, with calyx limb persistent; seeds numerous per locule, discoid, irregularly ellipsoid to angular-ellipsoid, compressed, small (1.5--2 mm), marginally winged and shortly erose with wing irregularly developed, surface finely foveolate-reticulated.