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Family:

Melastomataceae (Magnoliophyta)

Primary Citation:

Hooker's J. Bot. Kew Gard. Misc. 1: 379, t. 12. 1849

Accepted Name:

This name is currently accepted.

Description:

Description Author and Date: Fabian A. Michelangeli, Sep. 2011, modified from Penneys, D. S. & W. S. Judd. 2003. SIDA 20(3): 877-884.

Type: LECTOTYPE, designated by Penneys and Judd, 2003: "Melastoma. Hab - [illegible] District St. Anns [sic]. This is the most beautiful plant I have seen in Jamaica. Seeds 227." Macfadyen (K, H2001/02842-1, fragment A). ISOLECTOYPES, designated by Penneys and Judd, 2003: "Jamaica. Dr. McFadyen Tetrazygia fadyenii." (K, H2001/02842-2, fragment D!); "Tetrazygia? fadyenii Hook. Kew Journ. 1849. Jamaica. Macfadyen. Hooker 1849." (K, H2001/ 02842-3, fragment G!).

Nomenclature remarks: Three sheets located at K must be considered in the lectotypification of Tetrazygia fadyenii Hook. Each of the three sheets contain three twigs, which have been designated with consecutive letters for clarity, thus, sheet H2001/02842-1 has fragments labeled A through C, H2001/02842- 2 with fragments D through F, and H2001/02842-3 with fragments G through I. All specimens designated here as lectotype material were seen by Hooker in 1849, or earlier, and were collected by MacFadyen. Proof of this is demonstrated either by their label data or by representation in the illustration of the species published by Hooker in 1849. The BM collection H2001/02842-1 has attached to it the illustration that accompanied Hooker's description of the new species (Hooker's J. Bot. Kew Gard. Misc. 1:379, t. 12. 1849.). In that description, Hooker noted that MacFadyen provided him with specimens of the species, which he then named in his honor. This sheet also has a label, presumably written in the field by MacFadyen, that reads, "Melastoma sp. Hab - [illegible] District St. Anns [sic]. This is the most beautiful plant I have seen in Jamaica. Seeds 227." Written in a different hand at the top of that label is "Charianthus sp. nov." Fragment A, a leafy twig in fruiting condition, is here selected as the lectotype of Tetrazygia fadyenii Hook. This collection is from the Hooker herbarium, and was annotated by Hooker as T. fadyenii Hook. A fruit and seed of fragment A are represented as figures six and seven in the abovementioned illustration. Fragment B is in bud and flower, but cannot be definitively considered to have been seen by Hooker. Fragment C is a poor, sterile specimen. Label data are completely lacking on H2001/02842-2. However, fragment D, at least, was observed by Hooker, who wrote next to that flowering twig, "Jamaica. Dr. McFadyen Tetrazygia fadyenii." This fragment was likely used for the habit (figure unnumbered) and flower figures two and three of the illustration cited above, which it very closely resembles, and we consider it to be an isolectotype. Fragment E is a smaller flowering twig, and F is nothing more than a scrap with five mature fruits and the date 1850. The sheet is annotated in an unidentified hand as Charianthus fadyenii Griseb. From the sheet H2001/02842-3, it may be presumed that Hooker sent material of Tetrazygia fadyenii to Bentham as this sheet has "Herbarium Benthamianum 1854" stamps next to fragments G and I. Fragment G is a small flowering specimen overlaid by a label stating: "Tetrazygia? Fadyenii Hook. Kew Journ. 1849. Jamaica Macfadyen. Hooker 1849." It, therefore, appears that this fragment was included with the material originally under consideration by Hooker when he described the species. We consider it to be a possible additional isolectotype. The fruiting (and sparsely budding) twig H cannot definitively be assigned to either of the other two samples of this sheet. Fragment I is a budding twig with a label glued over it on which it is written, "Jamaica. Hooker 1843." The collector of fragment I is unknown. This sheet is annotated below as "Charianthus fadyenii Griseb. Triana in Linn. Trans. Vol. 28, p. 99."

Description: Evergreen shrubs or small trees to 10 m high. Druse crystals present. Bark smooth to shallowly, longitudinally fissured; young twigs terete (slightly quadrangular), gray-brown, essentially glabrous but with a very sparse indumentum of inconspicuous, stellate and unicellular, uniseriate hairs, the stellate hairs ca. 0.09-0.13 mm in diameter, nodes (1.93-)2.13-3(-5) mm in diameter, a slightly expanded, inconspicuous interpetiolar ridge present, with inconspicuous stellate pubescence, the hairs (0.05-)0.08-0.19(-0.21) mm in diameter. Leaf blade coriaceous, elliptic (widely elliptic or narrow obovate), (3.2- )4.4-6.5(-8) cm long, (1.8-)2.2-3.1(-3.5) cm wide, blades somewhat V-shaped, margins flat (very slightly revolute), light green, yellowish-green below, with midrib, secondary veins, and margins sometimes reddish; apex acute (barely obtuse), base acute, acute cuneate or cuneate (obtuse); adaxial surface of young blades with sparse stellate hairs (some sunken in pits) and unicellular hairs, the stellate hairs (0.05-)0.08-0.19 mm in diameter, mature leaves glabrous with extremely sparse stellate and unicellular hairs, abaxial surface of young blades with few unicellular or multicellular uniseriate hairs, sometimes with very dense stellate hairs (0.05-)0.08-0.19(-0.24) mm in diameter, mature leaves appearing glabrous but with few stellate hairs, often sunken in pits and appearing as punctations (0.05-)0.08-0.24(-0.25) mm in diameter; domatia (occasionally absent) of primary-axillary hair tufts, the domatial hairs multicellular multiseriate dendritic setae, domatia (0.48-)0.56-2.34(-2.80) mm long, (0.32- )0.33-1.47(-2.54) mm wide; margin entire; venation suprabasal (basal) with (1- )2 pairs of secondary veins, and 1 pair of inconspicuous submarginal secondary veins, the tertiary veins very indistinct (10-)12-19(-21), intergrading with quaternary veins at base and apex; midrib and secondary veins flat to slightly impressed adaxially, tertiary and quaternary veins very indistinct adaxially, midrib raised abaxially, secondary veins slightly raised to flat abaxially, tertiary and quaternary veins flat abaxially. Petiole (0.51-)0.60-1.35(-1.80) cm long, shallowly canaliculate, often reddish, moderately stellate pubescent, with the hairs ± evenly distributed on all parts of petiole or somewhat denser abaxially, these (0.06-)0.08-0.19(-0.25) mm in diameter. Inflorescence terminal, cymose, paniculate (loosely corymbose), (3.6-)5.7-8.8(9.5) cm long, (3.4-)3.5-5.4(-5.5) cm wide, with 2-3 orders of branching, the caducous bracts to ca 3 cm long; peduncle (1.9-)2.2-2.9(-3.6) cm long, first internode above peduncle (1.03-)1.30- 1.80(-2.20) cm long, first lateral internode (1-)1.1-1.7(-2.2) cm long, the flowers (21-)27-43(-76) per inflorescence. Pedicels (4.75-)5.25-7.75(-10.50) mm long, with stellate hairs (0.09-)0.11-0.16(-0.18) mm in diameter. Hypanthium cylindrical to suborbicular around ovary, tubular above ovary, (2.69-)2.75-3.60(-3.63) mm long as measured from base of hypanthium to torus, (2.07-)2.16-3.14(-3.47) mm wide, indumentum of stellate hairs, (0.05-)0.06-0.11(-0.18) mm in diameter, the portion of hypanthium free from ovary (0.97-)1.11-1.38(-1.57) mm long; inner hypanthium smooth (inconspicuously ridged), torus to calyx apex length (1.72-)2.50-3.54(-3.73) mm, torus to calyx notch length (1.63-)2.19-3.27(-3.32) mm. Calyx lobes 4, (0.09-)0.16-0.53(-0.69) mm long, (2.13-)2.32-2.97(-3.13) mm wide, lobes very broadly triangular (often to such a degree that the lobes are difficult to discern), the indumentum similar to that of hypanthium, the external calyx teeth (0.25-)0.33-0.63(-0.67) mm long, usually only a blunt knob on rim of hypanthium. Petals 4, bright red, oblong spatulate, the apex truncate, (9.50-)9.88-13.13(-13.63) mm long, (3-)3.13-4(-4.31) mm wide, glabrous, manyveined, erect or slightly spreading. Stamens 8, folded adaxially in bud, in two series, isomorphic, (19-)20-21.5(-22) mm long; filaments pink, slightly tapered towards apex, 14.5-16 mm long, with proximal filament segment (0.38-)0.41- 0.60(-0.67) mm wide, distal segment (0.22-)0.28-0.50(-0.53) mm wide; anthers yellow, (4.46-)4.94-5.94(-6.07) mm long, (0.53-)0.60-0.81(-0.82) mm wide, elliptic, slightly curving, opening by a single apical pore (0.19-)0.27-0.37(-0.45) mm wide. Ovary inferior, 2-loculate, (1.94-)1.97-2.94(-3) mm long, (1-)1.13- 1.41(-1.87) mm wide, with an apical appendage (0.94-)0.97-1.22(-1.25) mm long, with deeply intruded axile placentation; style pink or red, straight to shallowly S-shaped, glabrous, (20.5-)21-24(-24.2) mm long, (0.38-)0.41-0.57(-0.60) mm wide; stigma not expanded, papillose. Berries globose-urceolate, 4-7 mm in diameter, urceolate, deep purple. Seeds pyramidal, 1.35-1.50 mm long, 0.75-1.03 mm wide, the testa smooth. (see Hodge 1941, plate 6, figures 5 and 6).

Habitat and Distribution: Tetrazygia fadyenii is endemic to Jamaica. It occurs on limestone hills in xeric to mesic woodlands and forest edges from 450 to 950 meters elevation where it may be locally common (Fig. 2).

Phenology: Tetrazygia fadyenii has been collected in reproductive condition throughout the year, with the exception of the month of November.

Taxonomy and Systematics: Tetrazygia fadyenii is a very attractive melastome endemic to the Greater Antillean island of Jamaica. This species was first described by W. J. Hooker (1849) as Tetrazygia fadyenii. A. H. R. Grisebach (1864), misled by superficial morphological adaptations common to hummingbird pollinated plants, transferred the species to Charianthus Don. The incorrect placement of this species (as C. fadyenii (Hook.) Griseb.) persisted through subsequent classifications and floristic treatments by Triana (1871), Cogniaux (1891), Hodge (1941), Adams (1972), and Howard (1989). Judd and Skean (1991) recognized the non-monophyletic circumscription of Charianthus, and transferred this species to Miconia sect. Miconia. Convergent evolution, likely driven by parallel shifts to bird pollination in Charianthus and Tetrazygia fadyenii, has resulted in the presence of relatively large, red, pseudocampanulate corollas and nectar production in both taxa. We note that J. Dan Skean, Jr. has observed hummingbirds visiting flowers of T. fadyenii (pers. comm.; Skean & Samuels 1840). In the course of cladistic analyses of Charianthus based on both morphology and nuclear ribosomal ITS sequences (Penneys & Judd 2005), it was discovered that numerous morphological and molecular synapomorphies unite the six species of that clade. Additionally, Tetrazygia fadyenii was found to form a clade with T. bicolor and T. crotonifolia (and presumably, other species of Tetrazygia). Although T. fadyenii is currently best placed within Tetrazygia, ongoing investigations by the authors (and collaborators) on the phylogenetics of the Miconieae are needed to confirm this placement. The monophyly of Tetrazygia is supported in our preliminary analyses, but additional investigations, using more species, are needed. The monophyly of Miconia is doubtful, and recognition of other genera within the tribe may make Miconia paraphyletic, but this matter is beyond the scope of this paper. Some morphological characters distinguishing Tetrazygia fadyenii from Charianthus and uniting it with T. bicolor include: the presence of druse crystals (vs. these lacking), anthers opening by terminal pores (vs. slits), a 2-loculate (vs. 4-loculate) ovary, presence of mite domatia (vs. such structures lacking), spatulate (vs. broadly ovate) petals, the calyx constricted above the ovary (vs. not constricted), an adaxial thickening of the anther base (vs. anther base non-thickened), and rounded branches (vs. flat branches) of the stellate hairs. The presence of a hypanthium strongly constricted in fruit above the ovary may be a synapomorphy for Tetrazygia, and is clearly evident in T. fadyenii. Thus, this distinctive species should again be known by its basionym, T. fadyenii. Its resemblance to Charianthus is superficial. As outlined above, these similarities presumably reflect convergent adaptations to bird pollination. It is also of interest that the species of Tetrazygia occur chiefly over limestone, as does T. fadyenii, while the species of Charianthus sensu stricto grow on volcanic substrates. Jamaica is home to four species of Tetrazygia, of which three are considered to be endemic (Adams 1972). This pattern of endemism is the norm for Tetrazygia throughout its range; the majority of species in the genus are singleisland endemics. Tetrazygia fadyenii can be distinguished from other Jamaican members of the genus by the combination of elliptic (rarely widely elliptic or narrow obovate), essentially glabrous leaves, and bright red petals that are 9.5 to 13.5 mm long.