Boreallodape sp.

ENGEL, MICHAEL S., 2001, A Monograph Of The Baltic Amber Bees And Evolution Of The Apoidea (Hymenoptera), Bulletin of the American Museum of Natural History 2001 (259), pp. 1-1 : 1-

Boreallodape sp. indet.

MATERIAL: One specimen. Non­type. Female, B­W 163 ( AMNH) labeled: ‘‘Baltic amber: Eocene, Kaliningrad, Yantarny’’ // ‘‘ Boreallodape sp. indet., det. M. S. Engel.’’

COMMENTS: This specimen is mostly covered by debris, and although the wing venation, metasoma, and legs can be examined easily, the remainder of the body cannot be seen clearly.

Subfamily APINAE Latreille ‘‘Corbiculate Apinae’’

Apiariae Latreille, 1802a: 373. Type genus: Apis

Linnaeus, 1758.

DIAGNOSIS: The corbiculate apines, as the name implies, can be immediately recognized by the modification of the metatibia into a corbicula in nonparasitic females and workers. The presence of a rastellum, an expanded mandibular pollex, as well as the absence of the metabasitibial plate and pygidial plate also serve to distinguish this clade from other apines as well as the Xylocopinae (the only other subfamily of Apidae presently known in Baltic amber). At present , only the corbiculate tribes of Apinae are known from Baltic amber.

DESCRIPTION: Mandibular pollex expanded. Metatibia modified into corbicula; metabasitibial plate absent; inner apical margin of me­ tatibia with rastellum; auricle frequently present (except in parasitic forms and Meliponini ). Wings uniformly setose. Prepygidial fimbria and pygidial plate absent.

COMMENTS: The name ‘‘corbiculate bees’’, or Corbiculata, was first coined by Shuckard (1866: 165) for this specialized group of apine bees. This distinctive clade was once considered as the family Apidae (e.g., Michener, 1965, 1990) with the other apids relegated to the paraphyletic family Anthophoridae . The recent study of long­tongued bee phylogeny by Roig­Alsina and Michener (1993) resurrected the expanded concept of Apidae as it was employed by Michener (1944) and the corbiculate bees were incorporated into an expanded subfamily Apinae without a separate, formal rank. Should a formal rank be useful for recognizing the corbiculate apines, the supertribal name Apiti could be applied. Presently, an apine clade containing the non­corbiculate tribes Anthophorini, Centridini, Melectini, and Ericrocidini 6 is believed to be the closest relative of the corbiculate Apinae (refer to fig. 123).

This is the most common group of bees in Baltic amber. Three of the living tribes are eusocial to varying degrees and the phylogenetic position of the extinct corbiculate groups suggests that they too were eusocial (refer to sections on Cladistic Analyses, below). This social lifestyle perhaps can account for their abundance in amber in comparison to other groups. Living corbiculate bees typically collect resins and it is possible that the fossil species described below did as well, thus subjecting them more frequently to entrapment and fossilization.

The corbiculate clade consists of four extant tribes, briefly summarized as follows: The Apini (honey bees) are originally an Old World group but have been spread throughout the world by humans for agricultural purposes. Presently, fossils of Apini are only known from as far back as the early Oligocene ( Engel, 1998c, 1999c). The Euglossini (orchid bees) are strictly neotropical with two species in Miocene amber from the Dominican Republic (Engel, 1999b) and one extant species occurring in South American copal (Engel, personal obs.; Ross, 1998). The bumble bees, tribe Bombini , are distributed throughout the western hemisphere, the Palearctic, and the Oriental regions. The report of a bumble bee from tropical Africa (Tkalců, 1966) is actually based upon on an introduced species from South America (Sakagami, 1976; Michener, 1979, 1990; Williams, 1998). Numerous fossil bumble bees are known [Heer, 1867; Unger, 1867; Novak, 1877; Cockerell, 1906 (as Calyptapis ), 1931; Piton, 1940 (as Probombus); Zhang, 1990; Zhang et al., 1994; Rasnitsyn and Michener, 1991; Riou, 1999] but no true bombine has yet been discovered in amber. The report of a bombine in Paleocene amber from France (In Grimaldi, 1999) has yet to be confirmed; it is possible that this fossil is an electrobom­

6 Despite that shown in figure 123, relationships among these four non­corbiculate tribes are somewhat uncertain and nodes are not strongly supported. It is very likely that, once resolved, Anthophorini and Melectini will be sister groups and together sister to a monophyletic Centridini + Ericrocidini clade.

bine (if a small jugal lobe is present in the hind wing). Lastly, the stingless bees, tribe Meliponini , are diverse pantropically. Species are known in Late Cretaceous New Jersey amber (Michener and Grimaldi, 1988a, 1988b; Engel, 2000b), Miocene Dominican amber (Wille and Chandler, 1964; Michener, 1982; Camargo et al., 2000), Oligocene­Miocene Mexican amber (Wille, 1959), Colombian copal (Engel, personal obs.), Burmese copal [Cockerell, 1921 (not Miocene amber!)], Sicilian amber [ Tosi, 1896 (perhaps copal?)], and African copal [Engel, personal obs.; Stuckenberg, 1975 (not Baltic amber!); Zeuner and Manning, 1976; Wille, 1977]. Of all of these Recent tribes, only the meliponines are presently known in Baltic amber.

Key to Tribes of Corbiculate Apinae