First record of Chomelia triflora ( J . H . Kirkbr . ) Delprete & Achille ( Rubiaceae ) from Brazil

This paper presents the first record of Chomelia triflora from Brazil, to date a species only known from French Guiana. After examining herbaria collections and doing fieldwork in the Brazilian Amazon, we found that the species also occurs in and around the Ducke Reserve in the state of Amazonas, Brazil. Our finding increases the data about the Brazilian Amazon and contributes to the better knowledge of Chomelia in Brazil.


Introduction
Chomelia Jacq. is one of the largest Neotropical genera of the tribe Guettardeae, Rubiaceae, with 50 to 76 accepted species distributed from Central Mexico to Paraguay (Steyermark 1974, Anderson 1992).Its major centers of diversity are the Andean cloud forests, the Guyana Highlands, and the Atlantic forest of Brazil (Delprete et al. 2010).Thirty-seven species of Chomelia have been recorded for Brazil of which 28 are considered endemic (Barbosa and Pessoa 2015).The genus occurs in all Brazilian biomes, but is more diverse in the Atlantic Forest and the Cerrado.
Chomelia is characterized by having uniflorous or 3 to many flowered dichasium inflorescences, flowers with clearly lobed calyx, bifurcate stigma branch and fruits with pyrenes 2-locular.

Results
The specimens were identified by comparison with the original description and type material (Delprete et al. 2010, NOTES ON GEOGRAPHIC DISTRIBUTION Kirkbride 1997).Until now, C. triflora had been considered endemic to the French Guiana, where it was only known from the type locality, the Savane Roche de Virginie (inselberg), and two additional collections from the Nouragues Mountains, associated with rocky outcrops or gallery forests (Delprete et al. 2010).The oldest Brazilian specimens were collected in 1955, but had been erroneously identified as Chomelia estrellana Müll.Arg., which is an endemic species from the Atlantic forest and can be readily distinguished from C. triflora by its erect lateral branches (vs scandent), stipules 2-4 mm long (vs 5-10 mm) and peduncle 9-12 mm long [vs 20-60(-85) mm].

Discussion
The species seems to be restricted to a few very small populations in undisturbed forests.The two known populations are disjunct, one in French Guiana, in the region of the Nouragues Mountains, and the other near Manaus, Brazil (Fig. 1).These two areas are separated by a region known as the Transverse Dry Belt of Brazil (Davis et al. 1997), which presents a distinct seasonal climate with winter droughts that, when associated with sandy soils, favors the growth of a mosaic of vegetation types, including savanna formations and semi-open to open forests.However, the gallery forest along rivers and even the moist forests of some river basins may have connected the two regions during early Pleistocene, favoring the migration of species from the French Guiana into the Amazon Basin, as suggested by Mori and Prance (1987).
The new record of C. triflora presented here increases our knowledge on the distribution of the species but also suggests that its disjunction may be the result of poor sampling between the two localities where it occurs.It is conceivable that C. triflora could in fact occur in small populations in other unsampled forest fragments between the two sites.The time gap of 60 years between the collection and correct identification of Chomelia triflora, a 4-meter tall treelet, indicates that improving sampling efforts and training more taxonomists, especially in a country of continental dimensions such as Brazil, should be the key to reverse the taxonomic impediment in the Brazilian Amazon (Schum et al. 2007, Bortolus 2008, Ebach et al. 2011, Thomas et al. 2012).

Figure 1 .
Figure 1.Political map of South America showing the current distribution of Chomelia triflora in the state of Amazonas (Brazil) and in French Guiana.(Previous known distribution, black spots) of Chomelia triflora and the current record (red spot).