Simira robusta Margalho, G.S.Siqueira & Groppo, 2017

Margalho, Luciano Ferreira, Siqueira, Geovane De Souza, Delprete, Piero G. & Groppo, Milton, 2017, Simira robusta (Rubiaceae, Condamineeae), a new species from the Atlantic Rainforest of south-eastern Brazil, Phytotaxa 299 (1), pp. 118-124 : 119-122

Simira robusta Margalho, G.S.Siqueira & Groppo , sp. nov. ( Fig. 1 and 2 )

TYPE:— BRAZIL. Espírito Santo:Mun.Linhares, Reserva Natural Vale, Mata de Tabuleiro ,aceiro viveiro, 40°03’23.91’’W, 19°08’09.90’’S, 60–70 m, 4 September 2012 (fl), G. S. Siqueira 775 (holotype SPFR No. 16033!; isotype CVRD No. 13869!) .

Simira robusta is similar to S. grazielae Peixoto (1981: 1) in having corolla lobes with imbricate aestivation, lack of a membranaceous folding between the corolla tube and the stamens, and capsules dehiscing with bipartite valves forming a cross-like structure. The new species differs from S. grazielae by having peduncles 3–4.5 cm long (vs. 1.5–3 cm long in S. grazielae ), corollas 14–17 mm long (vs. 4–9 mm long), fruits 7–8.4 cm long (vs. 2.9–4.9 cm long) and inflorescences rachis, calyx and corolla antrorse pubescent (vs. glabrous to puberulous).

Tree; bark whitish, striated; branches terete, glabrous; vegetative buds antrorse pubescent. Stipules interpetiolar, early caducous, narrowly deltoid, 1.7–2.3 cm long, glabrous. Leaves opposite, crowded at branch apex, petiolate; petioles 1.8–3.3 cm long, canaliculate, with sparse trichomes on the adaxial side; blades oblong to broadly lanceolate, 13–21.5 × 5.5–9.5 cm, base acute or asymmetric to auriculate, apex acute to obtuse, sometimes slightly acuminate, glabrous above, pubescent on the midrib, tuft-domatia present in the axils of secondary veins below, brownish when dry, venation brochidodromous, midrib prominent on both sides; secondary veins 11–13(–14) on each side of the midrib. Inflorescences axillary on terminal nodes, thyrsoid, 4.3–6.2 cm long; peduncles 3–4.5 cm long; rachis antrorse pubescent; bracts deltoid, 5–8 mm long, glabrous. Flower buds ovoid. Flowers 5-merous, actinomorphic, pedicellate; pedicels 3–5 mm long, antrorse pubescent. Hypanthium turbinate, ca. 8 mm long. Calyx urceolate, 4 mm long, antrorse pubescent outside; lobes deltoid or truncate, ca. 0.5–1 mm long. Corolla light green, infundibular, 14–17 mm long; corolla tube 4–5 mm long, antrorse pubescent outside, with longitudinal lines of antrorse trichomes inside; lobes imbricate in bud, elliptic to lanceolate, 10–12 mm long, ovate to broadly ovate at apex, antrorse pubescent throughout. Stamens exserted, filaments 9–10 mm long, densely pilose at base; anthers dorsifixed, sagittate, ca. 6 mm long, light yellow. Ovary 2-locular; ovules numerous in each locule, inserted on the axial placenta; style 11–12 mm long, filiform, glabrous; style branches 2, 7–9 mm long. Fruit an elliptic capsule, 7–8.4 x 4–4.5 cm, woody, glabrous; each valve secondarily splitting into two lobes; the four lobes forming a cross-like structure, reflexed outwards when fully open. Seeds numerous, 4.3–5.5 × 2–2.3 cm.

Additional specimens examined (paratypes): — BRAZIL. Espírito Santo: Mun. Linhares, Reserva Natural Vale , 40°03’23.91’’W, 19°08’09.90’’S, 60–70 m, 30 October 2014 (fr), G. S. Siqueira & L. F. Margalho 1009 ( CVRD 15097 , NY [to be distributed], SPFR 16032 ) ; idem, 10 November 2016 (fl), D. A. Folli 7507 ( CVRD 15663 ) .

Etymology: —the specific epithet refers to the dimensions of inflorescences and fruits, which are larger and more robust when compared to similar species.

Vernacular name: —arariba-amarela (Siqueira 775).

Habitat: — Simira robusta is so far known from three collections made from a single tree growing in the Reserva Natural Vale, municipality of Linhares, Espírito Santo State, Brazil. The Reserve is owned by the Vale Mining Company, and is one of the largest protected areas in the Brazilian Atlantic forest, with an area of ca. 23,000 ha. The tree grows in forest understory, in a peculiar forest formation locally called “Mata de Tabuleiro”. This vegetation is characterized by being a lowland forest on flat soil, below 200 m altitude, ranging from the state of Rio Grande do Norte to the state of Rio de Janeiro ( Garay et al. 2003; Rizzini et al. 1997; Ruschi 1950; Silva & Nascimento 2001), although nowadays is severely fragmented. Extensive search in the ESA, GH, MBM, MO, NY, RB, SPF, and SPFR herbaria (acronyms according Thiers et al. 2012) revealed no specimen with the same characteristics of S. robusta .

Phenology: —The only known individual of Simira robusta was collected in two phenological stages, with flowers in September 2012 and November 2011 and with mature fruits in October 2014. As the sole individual known produced mature fruits, it is expected that other nearby individuals of the same species are present, but, after accurate searches in the surroundings no individual of the same species was found. Another hypothesis is the species could be self-compatible; however, self-incompatibility is well documented and described in Rubiaceae (e.g. Bawa & Beach 1983), and no data on reproductive biology in species of Simira is available. The seeds collected from the individual, albeit apparently well developed, were not tested to verify their viability.

Conservation status: — Because only one tree of Simira robusta was found so far, this species can be categorized as a data deficient (DD), since there is no sufficient information available on the abundance and distribution for a proper assessment of conservation status according to the IUCN criteria ( IUCN 2012). The species occur in the domain of the Brazilian Atlantic Rainforest, with its forested areas threatened by agricultural and urban pressure (Morelatto & Haddad 2000; Ribeiro et al. 2009).

Morphological similarities: — Simira robusta is most similar to S. grazielae , a species occurring in the Espírito Santo and Bahia states and also present in the Vale Natural Reserve (Barbosa et al. 2015). The two species are similar in having corolla lobes imbricate in bud, and fruits dehiscing with bipartite valves; the former differs from the latter by its larger inflorescences, flowers and fruits, and rachis, calyx and corolla with antrorse pubescent vestiture ( Tab. 1), characteristics which distinguish well the new species from S. grazielae . S. sampaioana ( Standley 1931: 12) Steyermark (1972: 307) , another morphologically similar species, also present in Southeastern Brazil, shares with S. grazielae and S. robusta the absence of a membranaceous folding between the stamens and the corolla tube. However, the fruits of S. sampaioana dehisce with entire valves (not bipartite), and its inflorescences, flowers and fruits are smaller than those of S. robusta ( Tab. 1). S. robusta shares with S. pikia (K. Schumann 1888: 328) Steyermark (1972: 307) , from Brazil, inflorescences and flowers antrorsely pubescent.

Simira hatschbachiorum J.H. Kirkbride (1997: 360) , another species endemic to Espírito Santo state, has larger inflorescences and flowers when compared with S. robusta (see Tab. 1). However, the fruits of S. robusta are larger, with bipartite valves at complete fruit dehiscence, while the valves are entire in S. hatschbachiorum . In addition, the inflorescences and flowers of S. hatschbachiorum are glabrous (vs. antrorse pubescent in S. robusta ).

Figures

FIGURE 1. Simira robusta. A. Habit with inflorescences; B. Detail of the domatia in tuffs of trichomes in adaxial face of the leaf. C.Apex of the branch showing stipule. D. Portion of the inflorescence. E. Bud. F. Flower in longitudinal section. G. Ovary in longitudinal section. H. Detail of the juxtaposed ovules I. Ovary, transversal section. J. Stamen. K. Open fruit. L. Seed.A–J from Siqueira 775. (holotype); K–L from Siqueira & Margalho 1009. Drawn by Bruno Simões Favaretto.

FIGURE 2. Simira robusta. A. Tree. B. Branch with flowers; C. Detail of inflorescences; D. Branch with fruits and seeds. E. Detail of the fruit, note the four lobes forming a cross-like structure, reflexed outwards when fully open. Photos by Geovanne S. Siqueira.