Chiococca

Jardim, Jomar G., Taylor, Charlotte M., Barbosa, Maria Regina & Pessoa, Maria Do Céo R., 2015, Taxonomic notes on Chiococca and Salzmannia (Rubiaceae, Chiococceae) in northeastern Brazil, with a new combination and a new species, Phytotaxa 202 (1), pp. 15-25 : 16-17

Notes on Chiococca and Salzmannia

As noted by Delprete (2004), Chiococca and Salzmannia are morphologically similar and their separation has sometimes been questioned. Delprete distinguished this taxa primarily based on the molecular analysis of Motley et al. (2005) and stated that they differ in inflorescence arrangement, branched in Chiococca vs. subcapitate in Salzmannia , and in their filament vestiture, pubescent in Chiococca vs. glabrous in Salzmannia . Müller (1881) additionally separated these genera by the number of corolla lobes, generally five in Chiococca vs. four in Salzmannia , and stigma shape, unlobed or very shortly bilobed in Chiococca vs. bifid in Salzmannia . However, the Similar variation in shape of Chiococca was expanded when Delprete (2004) described C. plowmanii Delprete (2004: 5) from northeastern Brazil, which has bifid stigmas.

In addition to these characters, our studies show that these genera also differ generally in corolla form, funnelform to campanulate in Chiococca (but tubular in C. plowmanii ), vs. tubular in Salzmannia ; in mature fruit color, white or yellowish white in Chiococca vs. pink to purple in Salzmannia ; in the production of a resinous exudate, very limited or usually absent in Chiococca vs. copious on vegetative and reproductive structures in Salzmannia ; and in corolla aestivation and floral biology, as detailed below. The young stems of Salzmannia are covered with a significant amount of this resinous exudate, which gives the plants an overall shiny appearance; the specific epithet of S. nitida Candolle (1830: 617) refers to this appearance. Chiococca also includes species with shiny leaves, such as C. nitida Bentham (1841: 236) , but this shininess is due to a waxy layer above the epidermis rather than exudates, and it is mainly found on the upper surface of the mature leaf blades. On the other hand, the new species of Salzmannia described below has pubescent filaments, and belongs to this genus because of several other features, thus the variation in filament vestiture does not seem to separate these taxa; similar variation in filament pubescence within the same species was described in Erithalis by Negrón-Ortiz (2005).

When Salzmannia was first described, it was incompletely known by Candolle (1830: 617), and its corolla aestivation was not noted. Subsequently, Müller (1881) characterized the aestivation of Salzmannia as valvate and that of Chiococca as valvate or narrowly imbricate. Both genera were described as having valvate corolla aestivation by Schumann (1891: 101–102), and subsequent authors treated Chiococca as having valvate corolla aestivation (e.g., Steyermark, 1974; Lorence 2012). However Delprete (2004) noted that C. plowmanii has narrowly imbricate corolla aestivation, in agreement with Müller (1881). And, our field observations found that the corolla lobes of S. nitida are narrowly imbricate in bud, with two lobes external and two internal. This corolla character agrees with the relationships of Salzmannia found by Motley et al. (2005) with Scolosanthus and Erithalis , both of which also have imbricate corolla aestivation. Scolosanthus is similar to Salzmannia in its habitat in seasonal vegetation, but does differ from Salzmannia in its spiny, usually subshrub habit with short internodes, small xerophytic leaves, pubescent filaments, fruits white or yellowish-white at maturity, and distribution limited to the Caribbean basin. Erithalis is similar to Salzmannia in its shrub or small tree habit and its habitat in seasonal or rather dry vegetation, but differs from Salzmannia in its lax cymose inflorescences with the flowers pedicellate, its corollas with 4–8 lobes, its fusiform stigmas that are minutely 2–8 lobed at the apex, its 2–10-locular ovaries and fruits, and its range in the Caribbean basin. Zappi & Nunes (2000) reported one species of Erithalis from northeastern Brazil, E. insularis ( Ridley 1890: 41) Zappi & Nunes (2000: 655) , well outside the rest of the range of that genus, and Negrón-Ortiz (2005) considered these taxon as a disjunct population of the widely, morphologically variable, Caribbean species E. fruticosa Linnaeus (1759: 930) . However, the classification of these taxa in Erithalis is problematic, and is discussed below.

Our field observations confirm that the flowers of Salzmannia nitida last for one day and are homostylous with well marked protandry. In these flowers the anthers are fully developed when the bud opens and undergo anthesis then, while the style is initially very short and the stigmas included. After anthesis,, the style elongates and positions the stigma above the anthers, at which time it apparently becomes receptive. Robbrecht (1988) documented a number of Rubiaceae genera with protandrous flowers that shed their pollen before or shortly after the corolla opens. This floral behavior has also been documented in Mitracarpus longicalyx Souza & Sales (2001: 483) , tribe Spermacoceae ( Souza et al. 2007) , and also in Chiococca alba ( Linnaeus 1753: 175) Hitchcock (1893: 94) ( Castro et al. 2008) except apparently without subsequent style elongation here. The floral biology of other species of Chiococca and Erithalis apparently has not been studied in detail, but based on study of herbarium specimens these both appear to have styles and stigmas that do not change position or size after the flower opens. The floral biology of Scolosanthus has also apparently not been studied, but based on herbarium specimens it appears to be similar to that of Salzmannia [ Scolosanthus densiflorus Urba (1903: 381) , Clase et al. 1342, MO!; Scolosanthus triacanthus ( Sprengel 1822: 47) Candolle (1830: 484) , Mejía & Zanoni 6425, MO!].