Hornschuchia santosii D. M. Johnson

Hornschuchia santosii D.M.Johnson

Figs 4E, 6

Brittonia 47 (3): 303, fig. 24 (Johnson & Murray 1995).

Type: BRAZIL – Bahia • (Teixeira de Freitas *), “Km 6 da rod. Teixeira de Freitas a Alcobaça”; [17°31′05.6″ S, 39°39′07.3″ W]; 9 Oct. 1971; T.S. dos Santos 2091; holotype: CEPEC [CEPEC00007576]!; isotype: NY [NY00008357]!.

Material examined

BRAZIL – Bahia • “Buerarema, Rodovia que liga Buerarema a Vila Brasil, km 14”; [15°03′40.9″ S, 39°14′28.1″W]; 9Feb.1982; A.M.de Carvalho 1172; CEPEC [CEPEC00028511]!, HEPH [HEPH00001089]!, NY [NY00395773]! • ibid.; 9 Feb. 1982; A.M. de Carvalho 1175; CEPEC n.v., HEPH [HEPH00001087]! • “ Canavieiras ” (Santa Luzia *); 15º22′ S, 39º11′ W; alt. 100 m; 15 Aug. 1984; M.M. Santos 169; CEPEC [CEPEC00037788]! • “ Santa Luzia, Vila São João. Reserva de mata do CEPLAC, entrada em bifurcação à direita da estrada Santa Luzia-Vila São João, 18, 5 km além do rio na saída de Santa Luzia, 4.6 km além da bifurcação e 1 km além de ponte de concreto da reserva”; 15º23′18.2″ S, 39º12′04.9″ W; alt. 97 m; 26 Oct. 2008; R. Mello-Silva et al. 3134; SPF! • “ Una ” (Santa Luzia *), “Estrada de Una para Santa Luzia, ca 1 km após a Vila São João, ca 20 km de Una, ramal à esquerda”; 15º23′ S, 39º12′ W; 4 Dec. 2002; P. Fiaschi 1226; CEPEC [CEPEC00094181]!, CEPEC00094205]!, NY [NY01806300]!, RB [RB00484635]!, SPF!.

Description

Shrubs or trees, 2–7 m tall. Leaves chartaceous, petiole 1–5 mm long, lamina 8.6–20.5(–25.7) × 2.8– 9.8 cm, narrowly oblong to elliptic, narrowly obovate to oblanceolate or narrowly ovate, both surfaces glabrous, base cuneate, rounded to obtuse, apex attenuate to acute or obtuse, primary vein impressed adaxially and raised abaxially, 9–14 pairs of secondary veins, raised adaxially, angles between primary and secondary veins 40–60°. Inflorescence 4–12-flowered in highly ramified branches, axillary, terminal or leaf-opposed, bracts absent. Flowers with pedicel 2–25 mm long, flower buds 4–9 × 1.5–3 mm, conical with rounded apex, covered in trichomes. Sepals completely connate, calyx cupuliform, apex truncate, 1–3 × 3–5 mm, densely covered in trichomes. Petals linear, white, 9–22 mm long, covered in trichomes, stamens 6–18, 2–3.5 × 0.5 mm, carpels 2–9, 1–3 × 0.5 mm. Monocarps 1–3, globose to ovoid with rounded to acute apex, 21–22 × 16–19 mm, glabrous, stipe 1.5 mm long, calyx persistent. Seeds 6–8, 12–15 × 7–8 mm, flattened ellipsoid with aril.

Distribution and habitat

Hornschuchia santosii is endemic to Bahia, only known from three localities, the municipalities of Buerarema, Santa Luzia and Teixeira de Freitas. The only records in the municipalities of Canavieiras, Santos 169, and Una, Fiaschi 1226, have their geographic coordinates in Santa Luzia, in the same place of the collection Mello-Silva 3134. This region is close to the border of these three municipalities; therefore, it is possible that the collections Santos 169 and Fiaschi 1226 were made in Santa Luzia. The species inhabits lowland tropical moist forest (Gouvêa et al. 1976; Thomas& Barbosa 2008; Fig. 6).

Phenology

Flowering from February to December, fruiting in December.

Preliminary conservations status

Hornschuchia santosii has an EOO of 1378 km 2 and an AOO of 12 km 2. It has been found at three localities, one of them in a conservation unit. It has not been collected in 10 years. Moreover, as already mentioned, the region H. santosii inhabits is endangered due to deforestation (Landau et al. 2008). Therefore, it should be considered Endangered, EN B1ab(iii)+2ab(iii), according to IUCN Red List Categories and Criteria (IUCN 2012).

Notes

Hornschuchia santosii is the only species with up to 18 stamens and 9 carpels, it is similar to H. obliqua, the note under the latter describes the differences between them.

Distribution, endemism and conservation

Hornschuchia is a threatened genus, 11 of its 12 species are classified either as Critically Endangered, Endangered or Vulnerable. Only H. bryothophe is categorized as of Least Concern following the IUCN criteria (IUCN 2012) (Table 1). We have inferred the conservation status of five species: H. citriodora, H. leptandra, H. linanarum, H. polyantha and H. santosii, all classified as Endangered. The remaining species have already been classified. One species is Critically Endangered, H. alba, nine species are Endangered: H. cauliflora, H. citriodora, H. leptandra, H. lianarum, H. mediterranea, H. mellosilvae, H. obliqua, H. polyantha and H. santosii, while one is Vulnerable, H. myrtillus (Table 1).

Seven species are known from only five or fewer localities: H. citriodora, H. leptandra, H. lianarum, H. mediterranea, H. mellosilvae, H. obliqua and H. santosii (Table 1). Four species have not been collected in more than 17 years: H. alba, H. leptandra, H. mellosilvae and H. obliqua. Only four species are found in conservation units: H. bryotrophe, H. citriodora, H. leptandra and H. myrtillus.

Hornschuchia is endemic to the Brazilian Atlantic Forest, as defined by law (Brasil 2006), occurring from the State of Pernambuco to Rio de Janeiro (Fig. 7A). The species with the widest distribution is H. bryotrophe with a single collection in Pernambuco, its main distribution is from Bahia to Rio de Janeiro (Fig. 1). One species is endemic to Rio de Janeiro, H. alba (Fig. 1). Seven species are endemic to Bahia: H. cauliflora, H. leptandra, H. mediterranea, H. mellosilvae, H. polyantha, H. obliqua and H. santosii (Figs 3, 5–6). Most species occur in moist lowland tropical forest. Eight species also occur in seasonal semideciduous forest: H. alba, H. bryotrophe, H. cauliflora, H. leptandra, H. lianarum, H. mediterranea, H. mellosilvae and H. myrtillus (Figs 1, 3, 5–6). Hornschuchia lianarum and H. mediterranea reach the seasonal deciduous forest of Bahia and are the only species occurring in this type of vegetation (Figs 3, 5).

Southern Bahia is the centre of species richness for Hornschuchia (8 spp.); followed by northern Bahia (4 spp.) and northern Espírito Santo (3 spp.; Fig. 7B). Southern Bahia, the region close to Ilhéus, is also where most of the specimens have been collected, ranging from 13 to 18 records per cell (Fig. 7C). The second region where most of the species have been collected is Espírito Santo, close to Linhares, with eight records per cell (Fig. 7C).

The total points of occurrence for the species of Hornschuchia were 105. Two bioregions were identified, one including the coast of Bahia and northern Espírito Santo, bioregion 1; the other encompassing Rio de Janeiro and southern Espírito Santo, bioregion 2 (Fig. 7D, Table 2). Nine species are the most indicative for bioregion 1: Hornschuchia bryotrophe, H. cauliflora, H. polyantha, H. leptandra, H. lianarum, H. mediterranea, H. mellosilvae, H. obliqua and H. santosii (Table 2, Fig. 7D). In bioregion 2, the most indicative species are H. alba, H. citriodora and H. bryotrophe (Table 2, Fig. 7D).