Electrobombus samlandensis, Engel, 2001

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-

Electrobombus samlandensis , new species Figures 59–63

Plate 5c, e

DIAGNOSIS: As for the genus.

DESCRIPTION: Female. Total body length 18.78 mm; forewing length 10.50 mm. Head longer than wide (length 3.40 mm, width 3.24 mm). Upper interorbital distance 1.50 mm; lower interorbital distance 1.45 mm. Interocellar distance indeterminate (owing to bubble that obscures the position of one lateral ocellus); ocellocular distance 0.35 mm; median to lateral ocellus 0.20 mm. Intertegular distance 3.75 mm. Basal vein basad cu­ a by three times vein width; 1rs­m distad by 1m­cu by seven times vein width; 2rs­m distad 2m­cu by vein width; first submarginal cell shorter than second and third combined; length of anterior border of second submarginal cell one­half that of posterior border; length of anterior border of third submarginal cell one­half of that of posterior border, 1.5 times length of anterior border of second submarginal cell; 15 hamuli, arranged in a single, evenly spaced series.

Integument, where visible between dense pubescence of head, mesosoma, and meta­ soma, smooth and impunctate except face, clypeus, and supraclypeal area with small, faint punctures separated by a puncture width or less, tegula with microscopic punctures separated by 2–3 times a puncture width, and terga and sterna imbricate.

Coloration of head and mesosoma black; metasoma, antennae, and legs dark brown. Wing membrane hyaline; veins strong and dark brown.

Pubescence generally yellowish­white. Mandible with dense, minute setae in apical halves of outer grooves. Labrum with widely scattered, short, simple, erect setae. Clypeus with scattered, erect setae, such setae slightly more numerous along lateral borders. Face with dense, short, appressed, plumose setae mostly obscuring integument intermixed with longer, erect to suberect, plumose setae. Vertex with long, plumose, erect setae. Gena with pubescence as described for vertex except setae with only a few, minute branches. Mesosomal (dorsal, lateral, and ventral) pubescence long, feathery plumose, and exceedingly dense, mostly obscuring integument. Tegula with rather sparse, short, appressed setae not obscuring integument. Long corbicular setae with numerous, minute branches intermixed with long, simple setae. Terga and sterna with minutely branched, dense, moderate­length, subappressed setae that partly obscure the integument.

MATERIAL: Two specimens. Holotype. Female (caste indeterminate), B­JH 94 ( AMNH) labeled: ‘‘Baltic amber: Eocene, Kaliningrad, Yantarny’’ // ‘‘ Holotype, Electrobombus samlandensis Engel’’.

Non­type. Female (caste indeterminate), Nr. 500 ( CJDL) labeled: ‘‘Nr. 500’’ // ’’ Electrobombus samlandensis ?, det. M. S. Engel’’. This individual is entirely covered in Schimmel. Those few characters that can be determined suggest that the specimen is a second individual of E. samlandensis but this will perhaps never be known with certainty. The specimen is even larger than the holotype and is the largest bee specimen known from Baltic amber (total body length 22 mm).

ETYMOLOGY: The specific epithet is a reference to the Samland Peninsula where most Baltic amber has been uncovered.

COMMENTS: This is presently the largest

63. Hind wing. Scale bar = 1 mm.

bee species preserved in amber (of any deposit!).

TRIBE ELECTRAPINI ENGEL, NOMEN TRANSLATUM

Electrapina Engel 1998a: 99 . Type genus: Electrapis Cockerell, 1908b .

DIAGNOSIS: The electrapine bees are a heterogeneous group of three genera resembling either bumble bees ( Bombini ) or, to a much lesser degree, honey bees ( Apini ). From the former tribe electrapines differ by the presence of a jugal lobe, absence of alar papillae, truncated or appendiculate marginal cell apex, reduction of the outer mandibular grooves, and presence of only one, reduced metatibial spur. From the Apini , the electrapines differ by the deep incision demarking the jugal lobe, the presence of outer mandibular grooves, the single metatibial spur (entirely absent in Apini ), the absence of long eye setae (some microscopic setae are present in many specimens as is typical for many bees), and the shape of the marginal and submarginal cells in the forewing, among other characters.

DESCRIPTION: Moderately sized (ca. 5.5–16 mm long), robust, densely pubescent bees. Mandible with weakened outer mandibular grooves. Labral width 2–3 times length. Clypeus slightly convex and weakly protuberant in lateral view or flat (in Thaumastobombus ). Compound eyes bare or with sparse, microscopic setae. Supraälar carina present; scutellum broadly rounded posteriorly and variously produced (ranging from projecting over metanotum and propodeum to over metanotum only). Claws of female with inner tooth (e.g., figs. 72, 83); arolium strong and present; single, reduced metatibial spur present; malus of strigilis with short, thickened anterior prong in addition to primary ventral velum (e.g., fig. 82); metabasitarsus with distinct auricle at base; metatibia without penicillum. Distal venation of forewing strong and present; marginal cell large and narrowly rounded at apex, slightly offset from wing margin, truncate or feebly appendiculate, cell longer than distance from its apex to wing apex; pterostigma present and short to moderately sized, much longer than prestigma, r­rs arising near to just after midpoint, margin within marginal cell variously produced; 1m­cu relatively straight; hind wing with distinct jugal lobe, lobe broadly and deeply incised; hamuli numerous or reduced (numerous in Electrapis and Protobombus , reduced in Thaumastobombus ); wing membrane without alar papillae. Sting not reduced; with or without microscopic barbs.

COMMENTS: There has been much confusion over the identity of Electrapis and its tribal position among the corbiculate bees. Recently I erected the Electrapina as a subtribe of Apini to accommodate the nominate genus as it had been conceived by more recent authors (e.g., Zeuner and Manning, 1976; Kelner­Pillault, 1970a; Engel, 1998a) but my recent revelations over the true identity and nature of the type species (see below in Comments under Electrapis and E. meliponoides ) have resulted in a radical reinterpretation of the group. Those bees believed to be Electrapis s.l. in recent decades, and thereby somewhat intermediate in character between Apini and Meliponini are, in fact, members of the Melikertini (treated below). The electrapines are, in fact, intermediate in some respects between bombines and the Apini + Meliponini clade (see Cladistic Analyses, below). Cockerell’s (1908b, 1909b, 1909c) notes on the genus, as well as the genus Protobombus , clearly indicate overall Bombus ­like bees (although some have a definite Apis ­like habitus) and provide the necessary characters to associate his species with the specimens described below as Electrapis and Protobombus . Other taxa (i.e., those thought to resemble meliponines) at

TABLE 8 Hierarchical Classification of Tribe † Electrapini

one time placed in or near Electrapis by Kelner­Pillault (1970a), Manning (1960), Zeuner and Manning (1976), as well as myself (Engel, 1998a), are reassigned to the Melikertini or in a few instances to other electrapine genera following the results of the cladistic analysis presented below.

The tribe Electrapini , even after the removal of Melikertes and Roussyana , may still be paraphyletic with respect to an Apini + Meliponini + Melikertini clade. Among the three genera of electrapines known, Electrapis is the most plesiomorphic and resembles not only Electrobombus (from which it differs most significantly by the tribal characters mentioned above) but living bombines as well. Protobombus appears somewhat intermediate between Electrapis and Thaumastobombus , the latter appearing most similar to the higher corbiculates (i.e., Apini , Meliponini , and Melikertini ). However, there is presently not enough cladistic information to resolve the issue, and this scheme is presented only as a working hypothesis upon which future studies can build. It is appropriate to pose the possibility that electrapines may represent a stem­group lineage from which the higher corbiculates originated. Table 8 summarizes the present classification of Electrapini .

Figures

Figs. 59–61. Holotype female of Electrobombus samlandensis, new species. 59. Oblique frontal view of head. 60. Outer surface of metatibia and basal portion of metabasitarsus. 61. Claw and arolium. Scale bars = 1 mm (a = fig. 60; b = fig. 59; c = fig. 61).

Figs. 62–63. Wings of holotype female of Electrobombus samlandensis, new species. 62. Forewing.