Two new endemic species of Myrtaceae and an anatomical novelty from the Highlands of Brazil
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- Proença, C.E.B., Soares-Silva, L.H., Silva, P.Í.T. et al. Kew Bull (2010) 65: 463. doi:10.1007/s12225-010-9221-4
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Campomanesia cavalcantina Soares-Silva & Proença and Psidium ratterianum Proença & Soares-Silva (Myrtaceae), two new species from the Brazilian highlands are described and illustrated. Campomanesia cavalcantina is similar to Campomanesia eugenioides (Cambess.) D. Legrand var. eugenioides, but differs from this species in being an hemixyle, by the narrow to broadly elliptic-falcate leaves 1.7 – 4.6 times as long as wide with 8 – 15 lateral veins, by the less densely glandular leaves and flowers, and by the lanceolate, c. 7 mm long bracteoles which are persistent to young fruit stage. Psidium ratterianum appears to be most closely allied to P. australe Cambess. Both species share the hemixyle habit, similar leaf shape, leaf ratio and floral morphology. P. ratterianum differs from that species by its narrow, ascendant, strongly bullate leaves, bracteoles which are persistent in the fruit, expanded, funnel-shaped stigma and smaller, elliptic fruits. Anatomically, Psidium ratterianum differs from other species of Psidium, and from other new-world Myrtaceae (Tribe Myrteae), in that the leaves are amphistomatic, a character known to occur in the Australian genus Leptospermum.
Key wordsamphistomaticCampomanesiafloraleaf anatomyPsidiumsavannaSouth America
Campomanesia cavalcantina Soares-Silva & Proença e Psidium ratterianum Proença & Soares-Silva (Myrtaceae), duas novas espécies do planalto central são descritas. Campomanesia cavalcantina é similar a Campomanesia eugenioides var. eugenioides (Cambess.) D. Legrand. Difere daquela espécie por ser um subarbusto recurrente com folhas estreito a largo elíptico-falcadas, 1,7 – 4,6 vezes mais longas do que largas, pelos 8 – 15 pares de nervuras secundárias, folhas e flores não fortemente glandulares e bractéolas laminares, estreito-elípticas com c. 7 mm comp. que persistem até a frutificação. Psidium ratterianum parece ser aparentada a P. australe Cambess. Ambas compartilham hábito subarbustivo xilopodífero, formato de folha, razão foliar e morfologia floral. P. ratterianum difere daquela espécie pelas suas folhas ascendentes, fortemente buladas, bractéolas persistentes nos frutos, estigma expandido, infundibuliforme e frutos menores, elípticos. Anatomicamente, Psidium ratterianum difere das espécies previamente estudadas de Psidium, e das outras espécies de Myrtaceae do Novo Mundo (Tribo Myrteae) pelas folhas anfiestomáticas, caráter conhecido apenas no gênero australiano Leptospermum.
The Central Brazilian Highlands are in the core area of the Cerrado biome, a poorly protected biodiversity hotspot (Mittermeier et al.2005). The Goiás and Distrito Federal highlands are notable for a high proportion of endemic species (Munhoz & Proença 1998; Simon & Proença 2000).
Campomanesia Ruíz & Pav. and Psidium L. are Neotropical genera that are also sister taxa (Lucas et al. 2007). They are trees or shrubs that share similar brochidodromus leaf venation, uniflorous inflorescences, a dichasium or a bracteate shoot and large, pentamerous flowers. The flower buds are either completely open with free calyx lobes, or the lobes are fused together and tear at anthesis, or are rarely calyptrate (Landrum 1987). The most important differences between Campomanesia and Psidium are in the ovary and fruits (Landrum 1982). In Campomanesia the ovary is (3 –) 4 – 18 locular (2 – 5 locular in Psidium). In the developing fruit of Campomanesia the locule wall becomes stony or heavily glandular forming a false testa (fleshy locule wall in Psidium), while the testa itself remains thin and soft (becoming bony in Psidium). Thus mature Campomanesia fruits frequently have only 1 – 4 developed locules (false seeds), each of which may contain 1 – 2 true seeds at maturity. Mature Psidium fruits have few to many bony, operculate seeds developing per locule on a peltate to lamellate intrusive placenta. Embryos are of a similar type in both genera, c-shaped in Psidium to cochlear in Campomanesia, the hypocotyl thickened and well-developed, the cotyledons relatively small.
Campomanesia ranges from Trinidad to Northern Argentina and from the coast of Brazil to Peru, Ecuador and Colombia. It is estimated that c. 29 – 37 species occur in the genus (Landrum 1986, 1987, 2001; Kawasaki 2000; Govaerts et al.2008). Psidium is naturally Neotropical in distribution (some species are pan-tropical weeds), occurring from southern Mexico to the Province of Buenos Aires in Argentina, including the West Indies as well as two Archipelagos in the Pacific, the Galapagos and Revillagigedo Islands. It has been estimated that c. 93 – 100 species occur in the genus (Landrum & Kawasaki 1997; Govaerts et al. 2008).
1. Campomanesia cavalcantinaSoares-Silva & Proençasp. nov. Maximae affinis Campomanesia eugenioides (Cambess.) Legrand var. eugenioides, sed distincta statura minora, virgultosa, glabritie; foliis angustioribus, 1.7 – 4.6 longa quam lata, sparsius punctatis, maturitate crassioribus ad nervo medio forte plicatis, secundariis venis 8 – 15; pedunculis minoribus, bifloris; floribus sparsius punctatis; bracteolis laminaribus, germen superans, anguste ellipticis, persistentibus. Typus: Brazil, Goiás, Cavalcante, 31 Aug. 2004, T. B. Cavalcanti et al. 3529 (holotypus UB; isotypus CEN).
Distribution. South America: Brazil, Goiás.
Specimens Examined. Brazil. Goiás: Alto Paraíso de Goiás, 14°09′48′′S, 47°35′35′′W, 23 Oct. 2004, E. Chaves & V. C. Mendes 74 (UB); ibid., 5 Dec. 2004, E. Chaves & L. H. Soares-Silva 138 (UB); ibid., 5 Dec. 2004, E. Chaves & L. H. Soares-Silva 140 (K); ibid., 18 Dec. 2004, E. Chaves et al. 164 (UB); Cavalcante, caminho para a cachoeira Santa Bárbara, 20 April 2003, J. F. B. Pastore et al. 560 (UB); ibid., Estrada Cavalcante-Minaçu, km 20, 13°38′42′′S, 47°28′39′′W, 1131 m, 31 Aug. 2004, T. B. Cavalcanti et al. 3529 (CEN, UB).
Habitat. Open, grassy savannas (cerrado) on rocky soil in the Chapada dos Veadeiros, Goiás; 1150 m. It occurs as solitary shrubs.
Conservation Status.Campomanesia cavalcantina occurs in the Chapada dos Veadeiros area on the fringes of the Parque Nacional da Chapada dos Veadeiros. The Chapada dos Veadeiros highland habitat above 1,100 m is an irregular polygon culminating with two massifs (Felfili 2007) above 1,300 m and estimated at most to cover 8,000 km2 with altitudes falling abruptly to the east and west and gradually to the northeast and south (Observatório Geográfico de Goiás 2008). Two populations are known, one between the town of Alto Paraíso de Goiás and the village of São Jorge and one 95 km north near the town of Cavalcante. This would qualify it in the IUCN (2001) category of Vulnerable VU B1a + b(iii), with two known populations and extent of occurrence estimated as less than 20,000 km2 in an area which has suffered continuous reduction in size and quality of habitat.
Phenology. Flowering specimens were collected in April and October. Specimens with developing fruit were collected in August and December.
Etymology. The epithet refers to the type collection locality, the town of Cavalcante, as well as the type collection (Cavalcanti 3529).
Notes.Campomanesia cavalcantina is similar and probably very close to C. eugenioides (Cambess.) D. Legrand var. eugenioides. Both species share leaves 3 – 7 cm long with acuminate apices, lateral veins which are ascendant at 45o to the midvein, triangular calyx lobes, petals c. 8 mm long and one gland per anther. It is distinguished by being an essentially glabrous shrub, with much narrower leaves that are 1.7 – 4.6 times as long as wide, with the leaf blade coriaceous at maturity, strongly folded along the midvein in both fresh and dried material with 8 – 15 pairs of lateral veins. The peduncles are also shorter and biflorous, and an immediately visible, diagnostic character is the presence of laminar bracteoles which are narrow-elliptic, c. 7 mm long, frequently persistent to young fruit stage. C. eugenioides is a dry forest tree with ovate to elliptic leaves, 1.2 – 2.9 times as long as wide, with 7 – 8 pairs of lateral veins, strongly glandular leaves and flowers, and bracteoles which are 1 – 2 mm long and deciduous in the young bud.
2. Psidium ratterianumProença & Soares-Silvasp. nov.P. australe Cambess. affinis, a qua imprimis differt ramulis quadrangularibus, subalatis, foliis ascendentiis, eliptici-elongatis, forte bullatis, amphiestomatica, bracteoliis persistentibus, stigma infundibuliformis expansa, et baccis minoribus. Typus: Brazil, Distrito Federal, Brasília, 7 Dec. 2005, C. Proença, M. B. S. Campos & P. I. T. Silva 3068 (holotypus UB).
Distribution. South America: Brazil, Distrito Federal.
Specimens Examined. Brazil. Distrito Federal: Fazenda Água Limpa, 22 Jan. 1980, H. L. Cesar 37 (UB); ibid., month? 1980, H. L. Cesar 361 (UB); ibid., 11 Dec. 1979, J. H. Kirkbride Jr. 4990 (UB); Parque Nacional de Brasília, 15°43′52′′S, 47°55′35′′W, 14 Dec. 2003, C. R. Martins 180 (UB); ibid., 3 March 2004, C. Proença & C. R. Martins 3016 (UB); Parque Olhos d’Água, 7 Dec. 2005, C. Proença, M. B. S. Campos & P. I. T. Silva 3068 (UB); Reserva Ecológica do IBGE, 15°46'41"S, 47°53′07′′W, 16 Jan. 2001, M. A. Silva 4781 (IBGE, K).
Habitat.Psidium ratterianum is apparently a narrow endemic of the Distrito Federal; 1000 – 1200 m. It has been collected in campo sujo, and cerrado sensu stricto, i.e. grassy fields with sparse or dense scattered low trees and shrubs. Four flowering collections mentioned on the label that the area had recently burned, so this species may flower when triggered by burning. Flowering collection Proença et al. 3068 was observed by one of us (C.E.B.P.) being visited, apparently with stigmatic contact, by a large black Bombus (Apidae) bee minutes prior to collection.
Conservation Status.Psidium ratterianum is apparently restricted to the Distrito Federal. There are four known populations within a radius of less than 5,000 km2, three of which are within reserves; of these, one was recently apparently eliminated by clearing and another is under threat by the invasive African grass Melinis minutiflora P. Beauv. (Martins et al.2004). This would qualify it in the IUCN (2001) category of Endangered EN B1, B2b(iii), that is, with a distribution <5,000 km2 in an area which has suffered continuous reduction in size and quality of habitat.
Phenology. Flowering specimens were collected in December or January and fruiting specimens in January and March.
Etymology. This name is a reference to James Alexander Ratter (Royal Botanic Garden, Edinburgh) for his pioneering studies of the flora of the Fazenda Água Limpa, the Universidade de Brasília Field Station, where this species was first collected.
Notes.Psidium ratterianum is possibly a new member of the recently revised Psidium grandifolium complex. This was treated by Landrum (2005) as having 3 species: Psidium australe Cambess. (with three varieties), P. grandifolium Mart. and P. missionum D. Legrand. Our species appears to be closest to P. australe var. australe, and would key out to that species due to similar flowers and near glabrous, obovate leaves. It is immediately distinguishable from other species of the complex by the strongly bullate, ascending leaves, persistent bracteoles, expanded, funnel-shaped stigma and smaller fruits.
A detailed study on the leaf anatomy of Psidium ratterianum showed to our surprise that it is amphistomatic. Amphistomatic leaves had not yet been recorded in the genus Psidium, or in any Neotropical members of the family Myrtaceae — tribe Myrteae (see Gomes et al.2009 for a recent review of the leaf anatomy of 28 species in ten genera of tribe Myrteae and references therein), although they do occur in Leptospermum J. R. Forst. & G. Forst. (Johnson 1980) of tribe Leptospermeae sensu Wilson et al. (2005). The characterisation of Psidium as a genus with hypostomatic leaves is based upon studies of P. cattleyanum Sabine (Arruda & Fontenelle 1994; Boeger & Wisniewski 2003), P. guajava L. (Souza 1971), P. guineense Sw. [as P. multiflorum Cambess.] (Backes 1971), P. ovale Spreng. [as P. hatschbachii D. Legrand] (Contin 1972) and P. rufum var. widgrenianum (O. Berg) Proença as P. widgrenianum O. Berg (Donato & Morretes 2005), as well as on two unpublished studies of P. basanthum O. Berg and P. australe Cambess. var. australe by two authors of this paper (S. M. F. C.; P. I. T. S.). Detailed results on the anatomy of this species will be presented elsewhere.
The authors thank Taciana B. Cavalcanti (CEN) for bringing the type specimen of Campomanesia cavalcantina to our attention, Eduardo Chaves for the collections from Alto Paraíso de Goiás and Maria Aparecida da Silva (IBGE) for kindly photographing her collection of the IBGE specimen of Psidium ratterianum at our request. We furthermore thank Claudenir S. Caires and Rosemary Wise for the illustrations. The Andrew T. Mellon Foundation (through KLARF — Kew Latin America Research Fellowships) is also thanked for funding a grant to visit the Royal Botanic Gardens, Kew.