Se presenta una revisión de las especies argentinas de Randia. A partir de este estudio se reconocen tres especies: R. ferox, R. micracantha y R. calycina, siendo ésta última una nueva cita para el país. Se propone excluir del país a R. armata, especie amplia y erróneamente citada para el área. Se analizaron aspectos taxonómicos, la anatomía vegetativa y morfología polínica de las tres especies. Todos los taxones son descritos y diferenciados a través de una clave dicotómica. Se incluyen además imágenes de los caracteres diagnósticos de las especies, mapa de distribución y observaciones ecológicas. Se proponen lectotipos para los nombres de los taxones Basanacantha, R. calycina y R. ferox. Randia micracantha var. glabra es tratada como un nuevo sinónimo de Randia micracantha. Se determinó que algunos caracteres anatómicos y polínicos son útiles para la diferenciación de las especies argentinas.

Randia brevituba is a new species of the Paranean region of Argentina and Paraguay. It differs from the closest species, R. ferox, which is sympatric, in having short corolla tubes of 4.7-5.4 mm in the pistillate flowers and 2.8-7.9 mm in the staminate flowers, calyx lobes varying in shape and size in the same pistillate flower, and globose fruits 14-17 mm long (versus corolla tubes of 25.0-27.0 and 22.6-34.0 mm long, respectively, calyx lobes equal in shape and size, and fruit 3-5 cm and ovoid, ellipsoid or subglobose in R. ferox). We also discuss the taxonomic concept and geographic distribution of Randia armata, and conclude that it is markedly different from R. brevituba and the other species in the Southern Cone studied here, and moreover, that it does not occur in the Southern Cone. We provide a taxonomic key to distinguish the new species from other species of Randia in the Southern Cone of America.

Editor: Maria von BalthazarPremise of research. The primary goal of this study is to describe the colleters on vegetative and reproductive organs in the Spermacoceae tribe and to characterize their morphoanatomy, their distribution, and some functional and evolutionary aspects.Methodology. The anatomy, development, and vascularization of colleters from 28 species were studied using standard light and scanning electron microscopy based on fresh and fixed material. Our results are interpreted within the framework of recent molecular phylogenies.Pivotal results. Standard-type colleters were found on stipules, calyx, and bracteoles, and they were also found on underground buds in five species of Galianthe. Six species have green colleters, and two have vascularized colleters. We discuss previously unknown functional aspects based on the Staelia glandulosa colleters and propose a new term: long-lived colleters.Conclusions. This article describes the anatomy of colleters in the Spermacoceae tribe of the family Rubiaceae in detail. The presence of underground colleters in Galianthe grandifolia is confirmed and extended to other species of the genus. Vascularization is recorded for the first time in colleters of Mitracarpus and Staelia. This study provides data about the type, distribution, and anatomy of colleters in Spermacoceae, contributing important information for ongoing phylogenetic studies in the tribe. The proposal of a new functional type of colleter based on anatomical, morphological, and ecological aspects, named long-lived colleter, reflects the need to perform further comprehensive studies based on multidisciplinary approaches.