First records of melanistic Euglossa (Hymenoptera: Apidae): evolutionary implications.

Neotropical orchid bees (Hymenoptera: Apidae: Euglossina) are conspicuous due to their vivid and metallic colors. Nevertheless, except for a few comments, usually concerning the appropriateness of using coloration as a taxonomic character (e.g. Rebêlo and Moure, 1996; Nemésio, 2005, 2009; Bembé, 2007), virtually nothing is known about color production and evolution in orchid bees. Based on studies on other organisms, it is hypothesized that orchid-bee setae are primarily pigmentcolored, whereas integument due its color to chemical (pigments) and physical (light refraction or reflection) factors (Nemésio, 2009). Very few color aberrations have been noticed among orchid bees, most of them concerning color alteration of setae, especially in Eulaema (e.g. Nemésio, 2002). No integumental color alteration has been reported in orchid bees to date. During surveys of orchid bees in northeastern Brazil (states of Paraíba and Pernambuco), two aberrant specimens of Euglossa carolina Nemésio, 2009 were collected. All characters (overall size, shape of metatiba, shape of mesotibial tufts, length of paraocular ivory markings and ivory markings on the scapes, punctation see Figures 1 and 2) clearly correspond to those of ordinary E. carolina specimens, except integument coloration. The specimen from Pernambuco (Figure 1) is entirely blackish, whereas the specimen from Paraíba (Figure 2), presents blackish coloration especially on frons, mesosoma and metasoma (Figure 2A-C). On each tergum, only a tiny distal stripe of green coloration remains (Figure 2A-B).