A New Species of Dionysia (Primulaceae) from Southern Iran

Abstract

Collections made in southern Iran, Fars Province in 1983, by Mr Mozaffarian, Tehran, have revealed a hitherto undescribed species of Dionysia. The number of species in the genus now stands at 41, 26 occurring in Iran, all but 3 of these being endemic to the country. Most species of Dionysia have a very narrow distribution, a number being confined, as far as it is known, to a single mountain. The majority are cliff dwellers (chasmophytes) inhabiting shaded or semi-shaded rock crevices. Although several species are remarkably Primula-like, most form dense tufts or cushions more reminiscent of the genus Androsace. However, the genus almost certainly finds it closest ally in Primula. The new species forms dense cushions with numerous small tight leafrosettes and solitary bright yellow flowers, clearly placing it in section Dionysia Fenzl subsection Bryomorphae Wendelbo (1961). Members of the subsection all have closely imbricate entire leaves, solitary sessile flowers, with the style not exerted in long-styled flowers. The corolla may be yellow, pink or violet, depending on the species; the majority have emarginate corolla-lobes. Most species in subsection Bryomorphae have an indumentum of long articulated hairs, often mixed with sessile or shortly stipitate glands, especially on the leaves, bracts and calyces. However, two species, D. bryoides Boiss., and D. zagrica Grey-Wilson are without articulated hairs, the indumentum consisting solely of sessile and shortly stipitate glands. The new species, D. sarvestanica, belongs to this latter association. It is at once distinguished from D. bryoides by its yellow rather than pink flowers and the entire rather than emarginate corolla-lobes. It is also superficially very similar to D. zagrica, differing primarily in the more open leaf-rosettes, the upper half of the lamina rather reflexed (not ascending to erect), the generally broader lamina, the larger more leaf-like bracts, the calyx, which is split to the base rather than for two-thirds of its length, and the short corolla-tube (at least in the long-styled flower). The entire corolla-lobes are a distinctive feature of the new species and D. zagrica. In both species the veins, present on the leaf-lamina in the upper non-hyaline half, are conspicuously raised and flabellate, especially on the lower surface, a character that they share in common with D. lamingtonii. This characteristic of raised veins is a feature of subsection Tapetodes Wendelbo which contains 4 species, D. tapetodes Bunge, D. denticulata Wendelbo, D. trinervia Wendelbo and the little known D. kossinskyi Czern. Members of