Cremastra

Abstract: Anthecological observations on an orchid Cremastra appendiculata var. variabilis were carried out during May and June, 1994, in Kobe, Japan. The pendulous, tube-shaped flowers were visited by three species of bees and two of syrphid flies. Only queens of a long-tongued bumble bee Bombus diversus diversus received the pollinarium on one of their fore-femora. The frequencies of Bombus flower visits were extremely low. A carpenter bee, Xylocopa appendiculata circumvolans, consistently robbed nectar by making a perforation at the flower base.

Abstract: Cremastra malipoensis G. W. Hu, a new rare species of Orchidaceae, is described and illustrated, and a taxonomic key to the species of the genus is provided. It occurs in southeastern Yunnan, China, near the border of Vietnam. It is most similar to C. appendiculata, but its inflorescences have fewer flowers (only 4-7), its flowers are positioned horizontally and become slightly pendulous, the lateral lobes of the lip are geniculate and twisted 900 at the base, and the mid-lobe of the lip is somewhat reflexed, rhombic to broadly ovoid, and 9-10 x 8-9 mm. The new species is known only from a single population and categorized under the ICUN criteria as critically endangered. Formal recognition is required for protecting this species, which grows sympatrically with more common species that are harvested as medicinal herbs.

Abstract: Mixotrophy (MX, also called partial mycoheterotrophy) in plants is characterized by isotopic abundances that differ from those of autotrophs. Previous studies have evaluated mycoheterotrophy in MX plants associated with fungi of similar ecological characteristics, but little is known about the differences in the relative abundances of 13C and 15N in an orchid species that associates with several different mycobionts species. Since the chlorophyllous orchid Cremastra variabilis Nakai associates with various fungi with different ecologies, we hypothesized that it may change its relative abundances of 13C and 15N depending on the associated mycobionts. We investigated mycobiont diversity in the chlorophyllous orchid C. variabilis together with the relative abundance of 13C and 15N and morphological underground differentiation (presence or absence of a mycorhizome with fungal colonization). Rhizoctonias (Tulasnellaceae, Ceratobasidiaceae, Sebacinales) were detected as the main mycobionts. High differences in δ13C values (– 34.7 to – 27.4 ‰) among individuals were found, in which the individuals associated with specific Psathyrellaceae showed significantly high relative abundance of 13C. In addition, Psathyrellaceae fungi were always detected on individuals with mycorhizomes. In the present study, MX orchid association with non-rhizoctonia saprobic fungi was confirmed, and the influence of mycobionts on morphological development and on relative abundance of 13C and 15N was discovered. Cremastra variabilis may increase opportunities to gain nutrients from diverse partners, in a bet-hedging plasticity that allows colonization of various environmental conditions.