Monographs Details: Tresanthera condamineoides Karsten
Authority: Delprete, Piero G. 1999. Rondeletieae (Rubiaceae). Part I. Fl. Neotrop. Monogr. 77: 1-226. (Published by NYBG Press)
Family:Rubiaceae
Description:Species Description - Shrubs to trees, to 15-20 m tall, to 30 cm dbh, usually single-stemmed frondose trees; bark grayish. Leafy branchlets glabrous, with soft pith in the center, easy to break, terete to subquadrangular, grass-green; older branches terete, pale brown. Stipules narrowly triangular, acuminate, 3-7 cm long, ciliolate, glabrous to sparsely puberulent outside, glabrous, with a basal area of colleters inside (Fig. 3E), dark green, readily caducous, leaving a scar encircling the stem 1.5-2.5 mm wide. Leaves 28-71 × 15-25 cm, LAV 1.5:1-3:1; elliptic, oblong, to oblanceolate; acute, obtuse to truncate at base, acute to obtuse at apex, sometimes short deltoid-acuminate; blade dark green above, pale green below, semi-coriaceous; drying olive-green, stiff-chartaceous; glabrous above and below, pellucid-punctate; primary and secondary veins glabrous, prominent below, secondary veins 16-25 each side; tertiary veins starting subparallel and openly reticulate in the center, faintly evident above, very evident below; petioles 3-7(-10) cm long, 3-7 mm thick, terete to adaxially concave, glabrous. Inflorescence single pauciflorous axes to thyrsoid-panicles, to 100 cm long; lateral branches (when present) 1-2 pairs, opposite to subopposite, (5-) 15-28 cm long; basal portion of axis not branched 14-33 cm long; rachis terete to obtuse-compressed, rachis and branches glabrous; flowers on rachis and lateral branches solitary or in several cymules subtended by a bracteole; bracts subtending basal branches leaf-like, semi-caducous, to 17 × 7 cm, lanceolate; distal bracts subtending the cymules and the flowers narrowly triangular, 4-15 × 3-7 mm. Flowers long-pedicellate, pedicels 10-25 mm long, glabrous; hypanthium obconical, 5-10 × ca. 3 mm, glabrous to puberulent. Calyx reduced to a minutely undulate (crenulate) margin, 0.5-1.5 × 4-6 mm, glabrous. Corolla campanulate with reflexed lobes, 20-30 mm long, orange-red outside, yellowish white to greenish white inside, semi-fleshy to subcoriaceous when fresh; tube with medial constriction, 1.1-1.8 × 5-9 mm, glabrous outside and inside, without internal ring of hairs; lobes 5, 1/3-1/2 of corolla length, 7-12 × 6-8 mm, ovate to deltoid, acute at apex, glabrous outside, microscopically (40×) papillose inside. Stamens 5, partially exserted, equal, attached 5-7 mm from the base of the tube; filaments 4-6 mm long, enlarged and flattened at base, glabrous; anthers convex toward the center, lanceolate, acute at apex, (8-) 10-13 × 1.3-2.8 mm, base rounded and bilobed, smooth throughout, dehiscing by common lateral triangular pore, 2.5-4 mm below the apex. Pollen exine foveolate (non-echinate). Style exserted, terete, 20-28 mm long, glabrous; style branches elliptic to narrowly ovate, 2.5-3 mm long, stigmatic surface smooth; immature fruits elliptic, reddish green, and semi-carnose when fresh. Capsules narrowly elliptic to obovoid, 15-24 × 8-12 mm, dark brown, sometimes with few lenticels, glabrous; disk obviously exceeding the calyx, black; disk septicidal dehiscence present in some old capsules. Seeds 1-1.5 × 0.33-0.53 mm.

Discussion:Tresanthera condamineoides is a rare species increasingly threatened with extinction by human pressure. It is easily distinguishable within the family by its laterally poricidal anthers and pellucid-punctate leaves (with Rustia). The flowers of T. condamineoides vaguely resemble those of Rustia occidentalis and Condaminea corymbosa in being reddish outside and greenish white inside, fleshy when fresh, and in their general shape, but differ from the latter two in having anthers strongly convex toward the center. Also, the anthers in Rustia are apically poricidal, while in Condaminea they dehisce by lateral slits.

The detailed original description by Karsten (1858) and its hand-colored illustration provide sufficient information to grasp the identity of T. condamineoides. In the Vienna Herbarium (W) two Karsten specimens of Tresanthera are preserved: one with a flowering inflorescence and a cymule with old capsules, bearing the label "Tresanthera condamineoides Krst. - Cumbre de Valencia - Pt Cabello - Dr Karsten" (unknown handwriting); the other with a terminal branch with two fully expanded leaves, and two cymules with old capsules, bearing the label "Tresanthera condamineoides Krst - Cumbre de Valencia - Pt Cabello" (unknown handwriting), with "H. Karsten. Dr." embossed on the label, and the annotation "! Sch." (in K. Schumann handwriting). I have selected the former specimen (having flowers in anthesis and mature capsules) as the lectotype of T. condamineoides, and the latter as isolectotype. Additional isolectotypes might also be found at LE (Tryon, 1963), but I did not examine material from that institution. A dubious fragment has been found at Field Museum (F), with a few anthers and a small piece of leaf; on the envelope is written "Tresanthera Condaminensis [orth. var.] Karst. - Karsten." No original labels are attached to the herbarium sheet, and the identity of the fragments preserved at F remain doubtful.

The label of Eggers 5812 (holotype of T. pauciflora) preserved at Munich (M) bears the following annotation in Schumann’s handwriting: "Certe non! potius Rustia spec, nov., Rustia pauciflora m." Solereder (1890) simply cited the name Rustia pauciflora from Schumann’s herbarium annotation, but without description, thus producing an invalid specific epithet. Schumann (1891), in Die Natürlichen Pflanzenfamilien, simply listed "T. pauciflora (Solered.) K. Schum.," also without description, causing this epithet to remain a nomen nudum. Finally, Solereder (1893) published a detailed description of T. pauciflora, validating Schumann’s specific epithet and stating that the single specimen to which he referred was "Eggers 5812 (Herb. Monac. [M!])", where the holotype is still preserved.

The main characters that Steyermark (1974) used to distinguish the three Tresanthera species recognized by him were corolla color, inflorescence morphology, and leaf shape. Examining complete sets of various collections, I noticed that the corolla color of Tresanthera ranges from yellowish orange to orange-red outside, and from yellowish white to greenish white (to pearl-white) inside (as in Condaminea corymbosa), making this character taxonomically insignificant.

The inflorescence morphology of Tresanthera varies from pauciflorous to sparsely cymose within the same set of collections (probably from single individuals), and is densely thyrsoid only in Bernardi 5829. In Rustia, the closest genus to Tresanthera, I have observed subsecund inflorescences and erect inflorescences in the same individual. I have not observed individuals of Tresanthera in the field, but it is expected that the same is true for this genus, and therefore the secundiflorous or erect inflorescences are not considered a reliable taxonomic character.

The leaves of Tresanthera are usually oblanceolate (but elliptic-oblong in Bernardi 5829), and the leaf bases vary from acute to obtuse (but are truncate in Bernardi 5829). The fruits of Tresanthera change in shape as they go through maturation, early on elliptic-ovoid and becoming narrowly obovoid with age.

After proposing the three Tresanthera species, Steyermark (1974) stated that they might be reduced to one or two species as further collections accumulated. Steyermark did not study the types housed in the European herbaria, which are crucial for understanding the identity of these taxa. Additional recent collections (and their accurate label data) throughout its range have helped me to unravel the confused taxonomy of Tresanthera. I conclude that the characters used by Steyermark (1964, 1974) to separate the three taxa are of little diagnostic merit, and this genus is here treated as monotypic: T. thyrsiflora is reduced to varietal rank, and T. pauciflora is placed in synonymy with var. condamineoides.