Stenostephanus Nees

Manzitto-Tripp, Erin A., Darbyshire, Iain, Daniel, Lucinda A. McDade Thomas F. & Kiel, Carrie A., 2022, Revised classification of Acanthaceae and worldwide dichotomous keys, TAXON 71 (1), pp. 103-153 : 144

Stenostephanus Nees in Martius, Fl. Bras. 9: 91. 1847

– Type: Stenostephanus lobeliiformis Nees.

= Kalbreyeriella Lindau in Notizbl. Bot. Gart. Berlin-Dahlem 8: 143. 1922, syn. nov. – Type: K. rostellata Lindau.

Kalbreyeriella has been distinguished from morphologically similar genera (i.e., most NW Isoglossinae, which are now included in Stenostephanus ) by the combination of its spicate inflorescences, rostrate corolla buds, relatively long and narrow upper lip of the corolla, and triangular and apically acute (minutely 3-lobed) lower lip of the corolla (e.g., Leonard, 1958; Wasshausen, 2013). However, based on morphological similarities, species of Razisea and Kalbreyeriella have been suggested as better placed in Stenostephanus ( Daniel, 1999) . Phylogenetic results of Kiel & al. (2006) support the inclusion of Kalbreyeriella in Stenostephanus . Stenostephanus can be characterized by bilabiate, more or less tubular corollas lacking a rugula, two stamens with monothecous anthers, these held with the style adjacent to the upper lip of the corolla, staminodia lacking, and capsular fruits with the retinacula remaining attached to the fruit wall. These plants also share pollen that is banded or “girdled” (i.e., “Gürtelpollen” sensu Lindau, 1895). More recently, McDade & al. (2019) subsumed a species of Costa Rican Kalbreyeriella into Stenostephanus .