Abstract Colleters are glandular structures related to young shoots protection. In several Angiosperm families, as in Rubiaceae colleters are taxonomically important. This study reports presence, location, morpho-anatomical structure, ontogeny and histochemistry of colleters in vegetative and reproductive organs in 6 species of Cephalanthus and 20 species representatives of the tribe Naucleeae. Primarily based on their color and their secretion color, they were classified into light (LC) and dark (DC) colleters. The LC are exclusive to the inner side of the stipule, while the DC are found in several vegetative and reproductive organs. Histochemical studies revealed that higher mucilage and phenol content in DC could explain the dark color secretion. Results were analyzed at genus, tribe and subtribe levels, evidencing the taxonomic relevance in the family. Finally, the presence of corolline colleters in angiosperm flowers was reviewed. It was confirmed that, besides Cephalanthus, they are only present in Adenoa (Passifloraceae) and Chamaecrista (Fabaceae). Therefore, structures described as colleters in Nerium (Apocynaceae) and Cuscuta (Cuscutaceae) corollas do not correspond to colleters. This proves that corolline colleter is a rare character in Angiosperms. To conclude we provide a record of presence/absence, type and distribution of corolline colleters in an Angiosperm phylogenetic tree.

Resumo Cephalanthus glabratus é uma espécie imperfeitamente conhecida da família Rubiaceae. Esta é uma planta medicinal muito utilizada pelos habitantes locais em sua área de distribuição, porém até agora tem recebido escassa atenção da comunidade científica, o qual é evidenciado na escassa literatura que trata do táxon. A espécie é um arbusto muito ramificado, com folhas verticiladas, inflorescências em glomérulos, fruto esquizocárpico, uma semente por mericarpo, e sementes com um estrofiolo proeminente e esponjoso. A espécie cresce somente em vegetação de áreas baixas alagáveis e está sempre relacionada às bacias dos principais rios da região, Paraguai, Paraná, Uruguai e Rio da Prata, e, portanto, é fortemente ameaçada pelas atividades humanas ao longo delas (hidrelétricas, desmatamento, avanços das áreas urbanas, redução das zonas úmidas etc.). Seguindo as diretrizes da IUCN e baseado em todos os dados disponíveis de distribuição, classificamos como NT (Near Threatened, quase ameaçada). Apesar de que gênero foi taxonomicamente revisado, a nomenclatura do tipo de Cephalanthus glabratus não foi por enquanto corretamente estudada, portanto, é revisada aqui. Uma descrição detalhada, dados ecológicos e de distribuição são adicionalmente fornecidos.

Abstract Cephalanthus glabratus is an imperfectly known species of the family Rubiaceae. It is a medicinal plant widely used by the locals in its area of distribution, however until now it has received little attention from the scientific community, which is evidenced in the few articles treating the species. The species is a much-branched shrub, with whorled leaves, glomeriform inflorescences, schizocarpic fruits with 1-seeded mericarps, and seeds with a large spongy strophiole. It grows only in the vegetation of the lowlands and is always related to the basins of the main rivers of the region, Paraguay, Paraná, Uruguay and Río de la Plata, and therefore is strongly threatened by the human activities along them (hydroelectric dams, deforestation, advances of urban areas, reduction of the wetlands, etc.). Following IUCN guidelines and all available distributional data, we rated it NT (Near Threatened). Despite the fact that the genus was taxonomically revised, the nomenclatural type of Cephalanthus glabratus was not correctly clarified, so we have done so here. A detailed description, ecological and distributional data are provided.

This paper deals with the study of leaf domatia in Argentine Rubiaceae, which are common morphogenetic structures on the underside of the leaves of woody plants, which can establish mutual relations with mites or ants. Tufts of hair, pockets, cavities and crypts: many families are classified into types common relatively well preserved. Around 290 families of “dicots” have domatia, Rubiaceae being the best represented with all known and transitional types. Domestic classification by molecular data, Rubiaceae divided into three subfamilies: Rubioideae, Ixorideae and Cinchonoideae. In Argentina inhabit 41 genera and 132 species of Rubiaceae, of which 34 are woody (27%). As result, tree domatia types were found: tuft of hair, pockets and crypt, present in 14 species of Rubiaceace. It is mentioned for the first time a domatia in a vine species of Manettia. The results were compared with recent molecular studies; this confirmed the plesiomorphic condition thereof, since different types are common to the three subfamilies almost all the tribes of the family. Based on this sampling, the following tribes completely lack domatia: Anthospermeae, Rubieae, Paederieae and Pavetteae.

Este trabajo estudia los domacios foliares en Rubiáceas argentinas, los cuales son estructuras morfogenéticas frecuentes en el envés de las hojas de plantas leñosas, que permiten establecer relaciones mutualistas con ácaros u hormigas. Se clasifican en tipos relativamente bien conservados comunes a numerosas familias: mechones de pelos, bolsillos, cavidades y criptas. Alrededor de 290 familias de “dicotiledóneas” tienen domacios, siendo Rubiaceae la mejor representada con todos los tipos conocidos y transicionales. La clasificación intrafamiliar según datos moleculares, divide a Rubiaceae en tres subfamilias: Rubioideae, Ixorideae y Cinchonoideae. En Argentina viven 41 géneros y 132 especies de Rubiáceas, de las cuales 34 son leñosas (27%). Como resultado se encontraron tres tipos de domacios: mechón de pelos, bolsillos y en cripta en 14 especies de Rubiáceas. Se menciona por primera vez domacios en una enredadera sufrútice de la familia, en el género Manettia. Los resultados obtenidos fueron contrastados con estudios moleculares recientes, lo que permitió confirmar la condición plesiomórfica de los mismos, ya que los diferentes tipos son comunes a las tres subfamilias y a casi todas las tribus de la familia. Basado en el presente muestreo, las tribus Anthospermeae, Rubieae, Paederieae y Pavetteae carecen completamente de domacios.