Rhipsalis aurea M. F. Freitas & I. M. A. Braga, sp. nov. Syst Bot. 34(3): 505-509. 2009TYPE: BRAZIL. Estado do Rio de ]aneiro, municipio de Nova Friburgo, Macao de Cima, estrada de acesso pela BR 116, 22°21'50"S, 42°30'08"W, 1201 m alt., 27 Oct 2004, I. M. A.Braga 7494 (holotype: RB!; isotype: R!).
Haec species a R. pulchra Loefgr. similis, sed ab ea habito sub-erecto minore, segmentis secundariis caulis minoribus, crescentia definita, perigonio flavo-aureo, fructu adpresso et globoso distinguitur.
Additional Specimens Examined-BRAZIL. Estado do Rio de Janeiro, municipio de Nova Friburgo, Macao de Cima, pr. Friburgo, 1,600 m alt., 4 Oct 1959, G. F. J. Pabst 5178 (HB, HBR); Sitio Sophronites,5 Oct1987, G. Martinelli 12252 (RB); Parque Estadual dos Tres Picos, Sitio Vale dos Sonhos, 22°19'43.6" S, 42°43' 27.5" W, 1,702 m alt., 23 Nov 2005, A. M. Calvente and L. M. Versieux 156,157 (RB, SPF).
Rhipsalis aurea is a microendemic, rare plant. It is known
only from five collections from three different localities in the Tres
Picos State Park in the city of Nova Friburgo, Rio de Janeiro State,
located in the Serra dos Orgaos. It occurs in high altitude forest between
1,200 and 1,700 m elevation. The vegetation of this region is the Brazilian
Atlantic Forest where
The newly described species belongs to the subgenus Erythrorhipsalis,
which is morphologically distinct in having campanulate flowers not
conspicuously immersed in the areoles (Barthlott and Taylor 1995). Within
this subgenus, R. aurea is most similar to R. pulchra,
having mesotonically to subacrotonically branched stem segments, the
primary of indeterminate growth (i.e. with variable length), and characteristic
oblique campanulate flowers. However, R. aurea is distinct
in having the primary stem segments stiff and the secondary stem segments
smaller and with determinate growth (Figs. 1-2). These stem characters
are also reflected in a quite distinct habit while R. pulchra
is long pendent, R. aurea is smaller and suberect. In addition, R. aurea
is markedly different in its golden yellow flowers and by the depressed-globose
translucent green fruits. Rhipsalis pulchra has pinkish-white
flowers and dark purple to white fruits (Table 1). Loefgren (1915) described
R. pulchra originally from Serra da Mantiqueira, but it can also be
found in the Serra dos Orgaos.
Epidermis anatomy has proved useful for separating closely allied Rhipsalis species (Calvente et al. 2008). Epidermis and pollen grain features also segregate R. aurea from R. pulchra. The epidermis of R. aurea has smaller stomata located at the same level as the regular epidermal cells, differing from the bigger sunken stomata complex found in R. pulchra (Fig. 3). In addition, pollen grains of R. aurea are solitary and the exine is conspicuously spiculate, unlike the pollen grains on R. pulchra, which are isolated or in tetrads. The exine of the latter species is punctate and does not possess spicules (Fig. 3).
The first collection of R. aurea was made in 1959 (Pabst 5178) and was kept in the herbaria HB and HBR. The specimen in HB was originally identified as R. gibberula F. A. C. Weber, a synonym of R. floccosa subsp. pulvinigera (C. A. Lindb.) Barthlott & N. P. Taylor. and the specimen at HBR was labeled R. rigida Loefgr., a synonym of R. dissimilis (G. A. Lindb.) K. Schum. Both identifications are erroneous since these specimens do not have the morphological features of either R. floccosa or R. dissimilis, two species that belong to sub genus Epallagogonium and have flowers conspicuously immersed in the areoles. Later, three new collections made it possible to describe R. aurea as a new species and enabled the link with the collection of Pabst 5178. The specific epithet aurea was chosen as an allusion to the golden yellow flowers, not found in any other Rhipsalis species. The flowering period of R. aurea is during the spring and early summer from October to November.