A new species of Siderasis from the state of Espírito Santo is here described. This new species is readily differentiated from S. fuscata by its sessile to subpetiolate leaves covered by hyaline to light-brown indumenta, blades with a well-defined white stripe along the midvein on the adaxial side of the blade, main axis of the main florescence elongate, thyrsi reduced to one elongate cincinnus, bracteoles present, anthers purple to bluish–purple, filaments and style apically purple to bluish–purple, aril cream-colored and slightly hyaline, and by the production of unique axillary flagelliform-shoots after the flowering period. I present a description of this new species, along with illustrations, a distribution map, comments on conservation assessment, ecology and taxonomy, and a table comparing the new species with the only other accepted species in Siderasis. Furthermore, I designate a lectotype and an epitype for S. fuscata.
Fig. 1- Siderasis albofaciata
Fig. 1. Siderasis albofaciata M.Pell. A, habit, showing the well-defined white stripe along the midvein of the leaves and the flagelliform-shoots with terminal rosettes. B, detail of the abaxial side of the leaf, showing the light-brown lanate indumenta. C, detail of the adaxial side of the leaf, showing the light-brown hispid indumenta. D, detail of the inflorescence, showing the solitary cincinnus. E, flower F, detail of the androecium and the gynoecium. G, detail of the capsules, the left one immature with evident accrescent sepals and the right one mature. H, detail of an open capsule, showing the uniseriate to partly biseriate arillate seeds. I, Dorsal view of a seed, showing the semi-lateral embryotega and the cream-colored, slightly translucent and thick aril. F by L. Kollmann (L. Kollmann et al. 11839, MBML), remaining photos by M.O.O. Pellegrini (M.O.O. Pellegrini et al. 337, RB, US).
Fig. 2- Siderasis inflorescence
Fig. 2. The inflorescence of Siderasis Raf. A, inflorescence diagram. B, rosette apex of S. albofaciata, showing: the main florescence (primary thyrse) with a flower at post-anthesis and a flower bud; the developed secondary thyrse with a flower at anthesis (arrow); and a young tertiary thyrse (arrow). C, synflorescence of S. fuscata, showing: the condensed synflorescence main axis and the long-pedunculate cincinni. P= prophyll; pB= peduncle bract on main synflorescence axis; *= aborted or dormant apex of main inflorescence axis (usually not observed); B= cincinnus bract; b= bracteole; f= flower; 1º bud= bud terminating cincinnus; 2º bud= bud in axil of peduncle bract with potential to develop into a secondary thyrse (coflorescence); 2º cincinnus= cincinnus of the secondary thyrse (coflorescence). Modified from Hardy and Faden (2004).
Fig. 3- Lectotype of Tradescantia fuscata
Fig. 3. Lectotype of Tradescantia fuscata Lodd. Photo courtesy of The Natural History Museum, London. This image is in the public domain and can be accessed through the Biodiversity Heritage Library.
Fig. 4- Siderasis fuscata
Fig. 4. Siderasis fuscata (Lodd.) H.E.Moore. A, habit, showing the petiolate leaves with silvery blotch along the midvein. B, detail of the bright-red hirsute indumenta. C, detail of the synflorescence detached from the rosette, showing the inconspicuous main axis and ebracteolate cincinni. D, upper view of a fertile rosette, showing many lilac flowers open at the same time. E, front view of a pale-lilac flower, showing the lacerated petals and completely white androecium and gynoecium F, detail of a mature capsule, showing the atro-vinaceous longitudinal stripes. Photos by M.O.O. Pellegrini (M.O.O. Pellegrini 217, RB).
Fig. 5-Siderasis map
Fig. 5. Distribution map of Siderasis Raf. Squares– Siderasis albofaciata M.Pell.; Circles– S. fuscata (Lodd.) H.E.Moore.
