Monday, March 18, 2019

[Botany • 2019] Mesosphaerum caatingense (Lamiaceae) • A New Species from the Semi-arid Caatinga Region of Northeast Brazil


Mesosphaerum caatingense Harley & J.F.B.Pastore

in Harley, Pastore, de Souza Soares, Fernando & Mota, 2019.

Summary
A new species, Mesosphaerum caatingense Harley & J.F.B.Pastore (Lamiaceae: tribe Ocimeae: subtribe Hyptidinae), is described from the semi-arid Northeast region of Brazil known as the Caatinga biome, included under the domain of the STDF (Seasonally Tropical Dry Forest). The generic placement and its conservation status are assessed and its phenology is discussed. The new species is compared with some of its morphologically allied species, M. pectinatum, M. irwinii and M. sidifolium. Illustrations, photographs, a distribution map and a key to Brazilian species are also provided.

Key Words: Hyptidinae, Mesosphaerum pectinatum, South America, STDF, taxonomy 

Fig. 1 Mesosphaerum caatingense.
 A flowering branch; B flower; C calyx and hypanthium; D corolla, opened to show stamens; E gynoecium. From the holotype.
Drawn by Michelle Mota.


 Fig. 2 Mesosphaerum caatingense.
 A flowering branch in vivo; B flowering branch; C flower; D calyx; E corolla; F open calyx; G open corolla and stamens; H, J calyx in fruit; K humid seed; L, M dry seeds.
Scalebar at F for B – M. 
All from the holotype. photos: a e. messias fernando; b – m j. floriano b. pastore & ray m. harley.

Mesosphaerum caatingense Harley & J.F.B.Pastore sp. nov. 

Type: Brazil, Paraíba: Município of Passagem, Fazenda Aba, 30 Nov. 2014, E. M. P. Fernando 193 (holotype CTBS!; isotype: CSTR).
  
Recognition. Of the four species previously recorded from Brazil, the new species most closely resembles Mesosphaerum pectinatum, but differs from this in the white corolla with two purplish blotches on the upper lip (pale pinkish or yellow-tinged and unblotched in M. pectinatum). The cymes are 16 − 18-flowered (20 − 40-flowered in M. pectinatum) and the lobes of the fruiting calyx are up to 1 mm long (1 − 1.5 mm long in M. pectinatum). ....


Distribution. Up until now, Mesosphaerum caatingense has been recorded from only three States in Brazil, all semi-arid zones of NE Brazil: Rio Grande do Norte, Paraíba and Pernambuco. The species may have often been overlooked as the very common M. pectinatum, and therefore records from other areas are likely to occur. It is known to occur in the south-west corner of the Município of Salgueiro, Pernambuco State; in the Seridó region of Rio Grande do Norte State, within the boundaries of the Municípios of Currais Novos and Jucurutu; and in the Município of Passagem, in Paraíba state. Map 1.

Map 1 Distribution map of Mesosphaerum caatingense compared with the ecoregions of Caatinga (according to Velloso et al. 2002).

Raymond Mervyn Harley, José Floriano Barêa Pastore, Arthur de Souza Soares, Emanoel Messias Pereira Fernando and Michelle Mota. 2019. Mesosphaerum caatingense (Lamiaceae), A New Species from the Semi-arid Caatinga Region of Northeast Brazil. Kew Bulletin. 74(1)  DOI: 10.1007/s12225-019-9795-4