Deutsche Version

Revision of the Euglossa cordata-group and functional morphology and faunistics of Euglossini (Hymenoptera, Apidae)

Benjamin Bembé

Summary

Euglossa sp. on NotyliaThe genus Euglossa currently contains 101 extant species in 5 subgenera and 12 species groups. The present work provides a detailed overview of the subgenus Euglossa (Euglossa). New keys are offered for the identification of males to the subgenera of Euglossa, the species groups in Euglossa (Euglossa), and for the first time to the species in the Euglossa cordata group.

The species in the Euglossa cordata group are studied and taxonomically revised using light- as well as scanning electron microscopy (SEM), and based on type material and collections holdings from various geographic regions. Instead of the previously recognized 21 species, the group is reduced to now 15 species. Five names, Eg.azureoviridis, Eg. cyanaspis, Eg. gaianii, Eg. ultima, and Eg. violaceifrons, are relegated to junior synonymy. Eg. erythrochlora becomes a subspecies of Eg. hemichlora. For Eg. tridentata, characters of the genitalia place it in the Euglossa cybelia group. The species so far carried under the name Eg. "azureoviridis" (auct.) has never been validly named. It is here treated under the provisional name Eg. BB-1. In addition, Eg. avicula, formerly separately valid in the Eg. purpurea group, is synonymised with Eg. heterosticta. Consequently, the following species and subspecies are here recognised as valid in the Euglossa cordata group: Eg. BB-1 (= Eg. "milenae" unpubl.); Eg. chlorina Dressler, 1982; Eg. cordata (Linnaeus, 1758);Eg. deceptrix Moure, 1968; Eg. despecta Moure, 1968; Eg. fimbriata Rebêlo & Moure, 1995; Eg. hemichlora hemichlora Cockerell, 1917; Eg. hemichlora erythrochlora Moure, 1968; Eg. jamaicensis Moure, 1968; Eg. leucotricha Rebêlo & Moure, 1995; Eg. liopoda Dressler, 1982; Eg. melanotricha Moure, 1967; Eg. modestior Dressler, 1982; Eg. platymera Dressler, 1982; Eg. securigera Dressler, 1982; Eg. variabilis Friese, 1899.

Species descriptions in the present work are supplemented with all available information on flower visiting and fragrance baits. The known distribution data are summarised and illustrated with maps. For the Euglossa cordata group, a cladistic analysis is performed, resulting in a hypothetical phylogenetic tree. The analysis includes Eg. mixta from the Euglossa analis group as an outgroup.

In a section on functional morphology, an overview of the fragrance-collecting behavior of male Euglossini is given. These animals collect fragrant substances (e.g. fragrant flower oils) from exogenous sources and accumulate them in their hind tibiae which are modified for this purpose. The subsequent fate of this material has been unknown. Here, a new hypothesis is presented that male orchid bees are capable of actively spraying off the stored fragrances. The fragrances are hypothesized to be transferred to the mid tibial tufts, which are then held such that when the hind wings are vibrated, the jugal combs hit the tibial tufts and spray off the fragrances. To test this hypothesis, the morphology of mid tibial tufts and hind wing jugal combs is examined on male Euglossini from all known genera. By physically manipulating rehydrated and thus remobilized specimens, the functional link between the two morphological structures can be established, including the generation of aerosol clouds. It is postulated that during the so-called “ventilating” behavior at their courtship sites the animals spray fragrances. This hypothesis is discussed with respect to previously published observations and assumptions.

Euglossa orellana on Coryanthe vazquesiiA section on faunistics in the present work covers two geographic areas from where very little or no information on Euglossini was previously available. The first surrounds the biological research station Panguana in the lowland rainforest of Peru (Departamento Huánuco). Using synthetic fragrances, Euglossini have been baited there by staff members and collaborators of the Zoologische Staatssammlung München (ZSM), and by R. Dressler. The associated collection currently comprises 32 species. This suggests that the fauna of Euglossini in the only 2 square km of primary forest around Panguana is very species-rich, especially relative to other areas investigated. In addition, the material has allowed the SEM documentation of important morphological characters for the rare species Euglossa rugilabris.

The second, very intensively studied area lies between the eastern edge of the Andes and the lowland rainforest at Villa Tunari, Departamento Cochabamba, Bolivia. In the years 1999-2002, Euglossini were collected there at fragrance bait traps and at orchid flowers in the so-called "Orchidarium Villa Tunari". The associated collection comprises 38 species. In addition, numerous observations could be made on pollination biology and fragrance preferences of many Euglossini species.

A discussion section compares results from the two study areas. Next to a collection from Tambopata National Park, Madre de Dios, Peru (Dressler 1985), these constitute the only faunistic data on Euglossine bees from that zoogeographic Region.