A new interpretation of the bee fossil Melitta willardi Cockerell (Hymenoptera, Melittidae) based on geometric morphometrics of the wing

Denis Michez,Michael Engel,Alexandre Dewulf,Manuel Dehon,Thibaut De Meulemeester

doi:10.3897/zookeys.389.7076

Abstract

Although bees are one of the major lineages of pollinators and are today quite diverse, few well-preserved fossils are available from which to establish the tempo of their diversification/extinction since the Early Cretaceous. Here we present a reassessment of the taxonomic affinities of Melitta willardi Cockerell 1909, preserved as a compression fossil from the Florissant shales of Colorado, USA. Based on geometric morphometric wing shape analyses M. willardi cannot be confidently assigned to the genus Melitta Kirby (Anthophila, Melittidae). Instead, the species exhibits phenotypic affinity with the subfamily Andreninae (Anthophila, Andrenidae), but does not appear to belong to any of the known genera therein. Accordingly, we describe a new genus, Andrenopteryx gen. n., based on wing shape as well as additional morphological features and to accommodate M. willardi. The new combination Andrenopteryx willardi (Cockerell) is established.

Highlights

Bees (Hymenoptera, Apoidea, Anthophila) are a monophyletic group of largely pollenivorous species derived from among the predatory apoid wasps (Engel 2001a, 2011, Michener 2007)
Taxonomic attributions of many compression fossils need objective and robust revision with modern procedures, such as geometric morphometrics (Michez et al 2012, Wappler et al 2012), and this is true for the diverse paleofauna from Florissant
The regression coefficient between the Procrustes distances and the Euclidean distances is close to 1 (0.9999). This means that the linear tangent space closely approximates the shape space, thereby permitting us to be confident in the variation amplitude of our dataset

Summary

Introduction

Bees (Hymenoptera, Apoidea, Anthophila) are a monophyletic group of largely pollenivorous species derived from among the predatory apoid wasps (Engel 2001a, 2011, Michener 2007). This clade probably appeared in the Early Cretaceous (~120 Myr) (Engel 2001a), and concomitant with the diversification of the Eudicots (Michener 1979, Cardinal and Danforth 2013). Taxonomic attributions of many compression fossils need objective and robust revision with modern procedures, such as geometric morphometrics (Michez et al 2012, Wappler et al 2012), and this is true for the diverse paleofauna from Florissant

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Conclusion