Paleomelitta nigripennis, 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-

Paleomelitta nigripennis , new species Figures 17–20 Plates 1c,d, 2a

DIAGNOSIS: As for the genus.

DESCRIPTION: Female. Total body length 14.65 mm; forewing length 10.50 mm. Head

wider than long (length 3.25 mm, width 4.03 mm). Compound eye width approximately twice that of gena. Interocellar distance 0.60 mm; ocellocular distance 0.50 mm; median to lateral ocellus 0.15 mm. Median and parapsidal lines strongly impressed (fig. 18). Intertegular distance 3.05 mm; mesoscutum length 1.05 mm; scutellum 2.5 times longer than metanotum; basal area of propodeum about as long as metanotum. Basal vein basad cu­a by vein width; second abscissa of Rs basad 1m­cu by four times vein width, straight, approximately orthogonal to M (fig. 20); 2rs­m distad 2m­cu by two times vein width; first submarginal cell subequal to second submarginal cell; posterior border of second submarginal cell approximately 1.25 times length of anterior border.

Labrum with small punctures separated by a puncture width or less, integument between smooth. Clypeus with small punctures separated by 1–2 times a puncture width on apical half, basal half punctures smaller, faint and sparse, integument between smooth. Su­ praclypeal area, face, vertex, and gena sculptured as on basal half of clypeus. Pronotum smooth and impunctate. Mesoscutum with small punctures separated by 1–2 times a puncture width except around median line separated by a puncture width or less, integument between smooth. Scutellum sculptured as on mesoscutum except punctures separat­ ed by 2–3 times a puncture width. Tegula with minute punctures separated by less than a puncture width on inner half, outer half impunctate, integument between finely imbricate. Metanotum imbricate. Pleura with sparse, minute punctures, integument between smooth. Propodeal lateral and posterior surfaces finely imbricate; basal area of propodeum strongly imbricate. Metasomal terga with minute punctures separated by a puncture width, integument between finely imbricate; sterna imbricate.

Coloration dark brown. Wing membranes exceedingly infumated, dark brown; veins black.

Pubescence fuscous. Labrum with scat­ tered, short (ca. 1 OD or less), erect, simple setae. Clypeus and supraclypeal area with scattered, short, suberect, simple setae; clypeus with two submedial patches of three (2 OD in length) simple setae (fig. 17). Face, vertex, and gena with scattered, simple, erect to suberect, short (1 OD in length) setae; setae of gena progressively longer toward postgena (reaching 3 OD in length). Pronotum with sparse, minute, suberect, simple setae except surface at dorsolateral angle and pronotal lobe with dense, plumose setae (1 OD). Mesoscutum with scattered, minute, erect, simple setae, setae sparse on central disc but more noticeable along borders. Scutellar pubescence as described for mesoscutum except posteriorly fringed with dense, plumose setae; axilla with more elongate (1.5–2 OD), simple, erect setae. Metanotum with scattered, short, suberect to erect, simple setae. Pleura with scattered, simple, erect setae (1.5–2 OD) except hypoepimeral area without setae. Lateral and posterior surfaces of propodeum with scattered, short, simple se­ tae; basal area of propodeum without setae. Metafemur without scopal setae; metatibia and metabasitarsus with scopae composed of dense, elongate, simple setae, setae longest on inner surfaces (3–4.5 OD). Anterior­facing surface of T1 with widely spaced, erect setae (2 OD), each with a few minute branches; remaining terga and apical margin of T1 with scattered, minute, simple, appressed setae; sterna with scattered, simple, erect, postgradular setae.

MATERIAL: Two specimens. Holotype. Female, B­JH 101 ( AMNH) labeled: ‘‘Baltic amber: Eocene, Kaliningrad, Yantarny’’ // ‘‘ Holotype, Paleomelitta nigripennis Engel’’. The block of amber containing the two bees is an impressive size (pl. 2a) and measures approximately 13.5 cm in length, 5.5 cm in width, and 3.75 cm in height.

Paratype. Female, in same piece of amber as holotype (see above).

ETYMOLOGY: The specific epithet is a combination of the Latin words nigra (meaning ‘‘black’’) and penna (meaning ‘‘wing’’) and is a reference to the darkened membrane of the forewings.

Family MELITTIDAE Schenck

Melittidae Schenck, 1860: 136 . Type genus: Melitta Kirby, 1802 .

DIAGNOSIS: This family consists of shorttongued bees with the fully exposed mesocoxa, V­shaped submentum, and short jugal lobe typical of the long­tongued bees while retaining the plesiomorphic ‘‘short­tongued’’ labial structure, absence of a stipital comb and concavity, and absence of a flabellum. Melittids also lack a preëpisternal groove and the scopa is limited to the metatibia and metabasitarsus.

DESCRIPTION: Labrum frequently much wider than long, apical margin fringed with bristles. Single subantennal suture; suture meets lower margin of antennal socket frequently at midpoint, although sometimes slightly laterad midpoint (either outer or inner side of lower margin), never meeting out­ er margin of antennal socket. Facial foveae absent. Lower lateral margin of clypeus not bent posteriorly on either side of labrum. Flabellum absent; glossa acute; glossal rod absent; paraglossa frequently reduced, sometimes absent; labial palpus with first two segments cylindrical, not sheath­like, third and fourth segments in line with preceding segments, not projecting laterally. Mentum elongate, tapering basally, curved over submentum to its articulation; apex of mentum articulated with prementum via fragmentum; submentum strongly V­shaped and sclerotized, submental arms articulating with cardines slightly above cardo­stipital articulations. Galeal blade equal or shorter than stipes, frequently longer than prepalpal section of galea; galeal comb present ; stipital comb and concavity absent; basistipital process elongate. Preëpisternal groove absent. Mesocoxa entirely exposed. Metabasitibial plate frequently distinct. Scopa restricted to metatibia and metabasitarsus. Jugal lobe of hind wing one quarter to one half as long as vannal lobe. Metapostnotum without pubescence. Pygidial plate and fimbria of female present; pygidial plate of male frequently absent. Volsella present ; penis valves do not form a distinct spatha.

COMMENTS: The subfamily Melittinae (sensu Michener, 1981b) contains three distinct groups that are not closely affiliated; each has numerous characters separating them from one another as much as the remaining subfamilies of the family. Herein I have separated Macropis from the subfamily Melittinae and resurrected the subfamily Macropidinae ; I have here added a second genus to this subfamily (described below). Likewise, the African genera Rediviva and Redivivoides , while retained in Melittinae , are restricted to their own tribe. The Melittinae is therefore reduced to two groups: tribe Melittini with Melitta s.l. and Dolichochile , and

TABLE 6 Hierarchical Supraspecific Classification of Melittidae (Currently recognized genera included but subgenera excluded.)

tribe Redivivini (new tribe; type genus: Rediviva Friese ) with Rediviva and Redivivoides . The Redivivini can be separated from Melittini by the reduced, shining, and smooth propodeal triangle and males with S7 bifid (Michener, 1981b). Table 6 summarizes a new higher classification of Melittidae .

The separation of Macropis from the Melittinae implies that the oil­collecting structures of the Macropidini and the Redivivini arose independently. This seems to be a valid conclusion since macropidines appear to share features with basal dasypodaines (e.g., Promelitta ) particularly in the presence of only two submarginal cells and, in fact, the structure of the second abscissa Rs in basal dasypodaines is difficult to distinguish from the state seen in Macropidinae .

Subfamily MACROPIDINAE Robertson

Macropididae Robertson, 1904: 42 . Type genus: Macropis Panzer, 1809 .

DIAGNOSIS: This subfamily resembles the Dasypodainae by the presence of only two submarginal cells in the forewing (i.e., loss of 1rs­m). In dasypodaines, however, the second abscissa of Rs is not widely separated from 1m­cu and is essentially orthogonal to M. From Melittinae , in the restricted sense that I have used it here, macropidines differ by the reduced number of submarginal cells, the presence of yellow maculations on the face of males, and the presence of a pygidial plate in males.

DESCRIPTION: Mandible with strong subapical tooth. Two submarginal cells, cells subequal in length; second abscissa of Rs slightly oblique, widely separated from 1mcu. Pygidial and prepygidial fimbriae strong. Males with yellow maculations on the clypeus; males with pygidial plate present .

COMMENTS: The subfamily as presently defined contains two genera ( Macropis and Eomacropis ), which I have segregated into two monobasic tribes. This is owing to the numerous, significant differences between the two genera, each with several apomorphic traits supporting their respective monophyly. They are sufficiently different to warrant placement in different tribes.

EOMACROPIDINI , New Tribe

TYPE GENUS: Eomacropis Engel , new genus.

DIAGNOSIS: This tribe differs from Macropidini most notably by the complete absence of the suite of oil­collecting adaptations seen in Macropis (e.g., velvety setae on thickened tarsi). Eomacropidini has an elongate metabasitarsus and vein r arises distad the middle of the pterostigma. The apomorphic presence of a strongly convex and medially carinate metanotum and V­shaped propodeum is immediately diagnostic.

DESCRIPTION: Labrum without median transverse ridge, with subapical elevation (fig. 21). Anterior border of scutellum gently biconcave (straight in Macropidini), posterior border rising well above metanotum (fig. 22) (not gently curving over to meet metanotum as in Macropidini). Metanotum strongly convex, with median longitudinal carina (fig. 22). Protarsi and mesotarsi not thickened, without dense, velvety setae; metatibia and metabasitarsus thin and elongate (not broad as in Macropidini), metabasitarsus at least three times longer than wide (fig. 24); metatibia without oil­collecting setae; metabasitibial plate strong, broadly rounded (fig. 25); metabasitarsus with setae present on distal process; metabasitarsal setae unmodified. Vein r­rs arising distad middle of pterostigma (fig. 23). Propodeum strongly V­shaped, dorsal­facing surface not transverse.

Figures

Fig. 17. Frontal view of head of holotype female of Paleomelitta nigripennis, new species. Scale bar = 1 mm.

Fig. 18. Dorsal view of mesosoma, posterior border of prosoma, and anterior border of metasoma of holotype female of Paleomelitta nigripennis, new species. NOTE: The depicted incision in the hind wing is the jugal fold demarcating the apical margin of the jugal lobe; the vannal fold is positioned just under the posterior edge of the forewing. Scale bar = 1 mm.

Fig. 19. Distitarsus, claw, and arolium of holotype female of Paleomelitta nigripennis, new species. Upper image is an outer view; lower image is an inner view. Scale bar = 0.25 mm.

Fig. 20. Forewing of holotype female of Paleomelitta nigripennis, new species. Scale bar = 1 mm.