Diversity of labellar micromorphological structures in selected species of Malaxidinae (Orchidales)

Abstract

There are no papers examining the labellar micromorphology in Malaxidinae in detail. The aim of this paper is to present the results of labellar micromorphology of our studies on Malaxidinae. The micromorphology of nine species was examined and described (calli, nectaries, OP structures, concavities). These species are divided into six groups of which the lip morphology probably represents different forms of attracting and rewarding pollinators. Group one consists of Disticholiparis gregaria and Platystyliparis aurita with characteristic globular nectary and pad-like callus. The second group with Liparis nervosa has two conelike convexities. The third one is represented by Liparis sutupensis with spread lip, the basal callus, and the epichile often eroding with age. The fourth group (Stichorkis cespitosum) has a massive hypochil with basal callus and delicate epichil. The fifth group (Microstylis ophioglossoides, Dienia ophrydis) is characterized by a lip with developed lateral lobes, three deep concavities in the middle part, an erect callus, and many raphide cells.Crepidium cf. rheedii and Crepidium dryadum from the sixth group have a three-lobed lip with entire or toothed mid-lobe, basal callus, cavity surrounded by a rim and OP structures with raphide cells. We also emphasized the different way and place of nectar secretion in the subtribe and gave some suggestions about pollination strategies.

Keywords

• labellar micromorphology
• pollination
• Malaxidinae
• Orchidaceae
• light microscopy
• scanning electron microscopy