Protobombus tristellus Cockerell, 1909c: 24

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-

Protobombus tristellus Cockerell, 1909c: 24 . Electrapis (Protobombus) tristellus (Cockerell) ;

Zeuner and Manning, 1976: 233.

DIAGNOSIS: This species is similar to P. indecisus and P. hirsutus but can be distinguished from both by the apical margin of the clypeus not extending below the lower tangent of compound eyes.

DESCRIPTION: Female. Total body length 6.13 mm; forewing length 5.13 mm. Head wider than long (length 1.78 mm, width 2.31 mm). Upper interorbital distance 1.47 mm; lower interorbital distance 1.25 mm. Interocellar distance 0.44 mm; ocellocular distance 0.39 mm; median to lateral ocellus 0.09 mm. Lower third of clypeus below lower tangent of compound eyes. Intertegular distance 1.72 mm. Basal vein confluent with cu­a, straight; second abscissa Rs arched; 1m­cu basad 1rsm by six times vein width; 2rs­m confluent 2m­cu, strongly arched; posterior border of second submarginal cell 2.5 times length of anterior border; posterior border of third submarginal cell twice length of anterior border, anterior border 1.5 times as long as anterior border of second submarginal cell.

Labrum imbricate and impunctate. Clypeus with small, faint punctures separated by 1–2 times a puncture width, integument between smooth. Supraclypeal area, face, vertex, gena, and postgena with sparse, small, faint punctures, integument between smooth. Pronotum smooth and impunctate. Mesoscutum and scutellum with sparse, faint punctures, integument between smooth. Pleura with sparse, small punctures, integument between smooth. Propodeum smooth and impunctate. Corbicula smooth and impunctate. Metasomal terga smooth and impunctate; sterna finely imbricate and impunctate except apical margins more strongly imbricate.

Where evident, integument dark brown and shining. Wing membrane hyaline; veins dark brown.

Pubescence whitish. Labrum with short, scattered, erect setae. Clypeus with scattered, short, simple, suberect setae intermixed with scattered, minute, appressed, simple setae. Face below level of antennal sockets with appressed, short, minutely plumose setae, setae numerous but not obscuring integument; supraclypeal area, vertex, gena, and remainder of face with scattered, suberect or erect, simple setae, setae of vertex and gena with minute branches. Postgena with scattered, short, erect, simple setae. Pronotum with sparse, short, suberect, simple setae except those of dorsolateral angle and pronotal lobe dense, moderately long, erect, and plumose setae. Mesoscutum with scattered, short, erect, minutely plumose setae. Tegula with sparse, appressed, scattered, minutely plumose setae. Scutellar setae as described for mesoscutum except setae dense and elongate on posterior border. Mesepisternum with moderately long, scattered, erect, simple setae and intermixed with scattered, minute, appressed, simple setae; hypoepimeral area without longer setae, only with minute, appressed setae; metepisternum with setae as on mesepisternum except simple and distinctly more dense on dorsal half than on ventral half. Setae of lateral and posterior surfaces of propodeum as described for ventral half of metepisternum except setae minute; basal area of propodeum without pubescence. Corbicular setae minutely plumose, inner surface of metatibia mostly covered by keirotrichiate field, field separated from metatibial apex by length approximately equal to one­half its width; metabasitarsus with scattered, short, simple setae, posterior edge with longer setae, inner surface with seven comb rows. Metasomal terga with sparse, minute, appressed, simple setae, slightly longer on more apical terga; sterna with suberect to erect, short to moderately long, scattered setae, each with a few minute branches, setae entirely postgradular.

MATERIAL: One specimen. Neotype (here designated). Female, worker caste, MB. I.1943 ( ZMHB) labeled: ‘‘Museum für Naturkunde Berlin, Paläontologisches Museum, Inv. Nr. MB. I.1943 ’’ // ‘‘50b [handwritten label]’’ // ‘‘ Neotype, Protobombus tristellus Cockerell , desig. M. S. Engel’’.

Protobombus hirsutus (Cockerell) , new combination Figure 77 Plate 5d

Chalcobombus hirsutus Cockerell, 1908b: 326 . Cockerell, 1909b: 12. Zeuner and Manning, 1976: 207.

DIAGNOSIS: This species is most similar to P. indecisus but differs by the separation of the keirotrichiate field from the metatibial apex being equal to one­half of its apical width and the posterior border of the third submarginal cell only twice as long as the anterior border.

DESCRIPTION: Female. Total body length 8.01 mm; forewing length 6.38 mm. Head wider than length (length 2.19 mm, width 2.25 mm). Upper interorbital distance 1.41 mm; lower interorbital distance 1.19 mm. Interocellar distance 0.44 mm; ocellocular distance 0.34 mm; median to lateral ocellus 0.13 mm. Lower half of clypeus below lower tangent of compound eyes. Intertegular distance 1.88 mm. Basal vein confluent with cu­a, straight; second abscissa Rs arched; 1m­cu basad 1rs­m by six times vein width; 2rs­m distad 2m­cu by vein width, strongly arched; posterior border of second submarginal cell approximately five times length of anterior border; posterior border of third submarginal cell 1.75 times length of anterior border, anterior border slightly more than twice as long as anterior border of second submarginal cell; hind wing with eight distal hamuli arranged in a single, evenly spaced series; hind wing with first abscissa M approximately equal in length to second abscissa M+Cu.

Labrum imbricate and impunctate. Clypeus with sparse, small, faint punctures, integument between faintly imbricate. Supraclypeal area, face, vertex, gena, and postgena with sparse, small, faint punctures, integument between smooth. Pronotum finely imbricate. Dorsum of mesosoma obscured by Schimmel and sundry small items of debris. Pleura impunctate finely imbricate. Corbicula with remains presumably of pollen covering surface. Metasomal terga and sterna finely imbricate.

Where evident, integument dark brown and shining. Wing membrane very lightly fuscous; veins dark brown.

Pubescence whitish or slightly fuscous. Labrum with short, scattered, erect, simple setae. Clypeus with scattered, short, simple, suberect setae intermixed with scattered, minute, appressed, simple setae. Face below level of antennal sockets with appressed, short, minutely plumose setae, setae numerous but not obscuring integument; supraclypeal area, vertex, gena, and remainder of face with scattered, simple, suberect or erect setae, a few on vertex and gena with minute branches. Postgena with scattered, short, erect, simple setae. Pronotum with sparse, short, suberect, simple setae except along posterior border and covering pronotal lobe with moderately long, erect, dense, plumose setae. Pubescence of mesosomal dorsal surface difficult to interpret, those mesoscutal setae appearing through layer of Schimmel and debris appearing to be scattered, moderate­length, erect, and minutely plumose; scutellar setae as described for mesoscutum except setae dense on posterior border and more elongate. Pleura with scattered, long, erect, simple setae. Lateral and posterior surfaces of propodeum as described for pleura except setae minute; basal area of propodeum without pubescence. Corbicular setae simple, inner surface of metatibia covered by keirotrichiate field, field separated from metatibial apex by length approximately equal to one­half its width; metabasitarsus with scattered, short, simple setae, posterior edge with longer setae. Metasomal terga with sparse, minute, appressed, simple setae; sterna with scattered, long, erect, fuscous, simple setae along apical margins.

MATERIAL: Four specimens. Neotype (here designated). Female, worker caste, B­ JH 92 ( AMNH) labeled: ‘‘Baltic amber: Eocene, Kaliningrad, Yantarny’’ // ‘‘ Neotype, Chalcobombus hirsutus Cockerell , desig. M. S. Engel’’ // ‘‘ Protobombus hirsutus (Cockerell) , det. M. S. Engel’’.

Non­type. Female, worker caste ( CJVG) labeled: ’’ Protobombus hirsutus (Cockerell) , det. M. S. Engel’’.

Non­type. Female, worker caste, Nr. 1254 (CHFG) labeled: ‘‘Nr. 1254, Balt. Bernstein’’ // ‘‘ Protobombus hirsutus (Cockerell) , det. M. S. Engel’’.

Non­type. Female, worker caste, Nr. 1255 (CHFG) labeled: ‘‘Nr. 1255, Balt. Bernstein’’ // ‘‘ Protobombus hirsutus (Cockerell) , det. M. S. Engel’’.

Figures

Figs. 75–77. Wings of Protobombus species. 75. Forewing of Protobombus basilaris, new species. 76. Hind wing of P. basilaris, new species. 77. Forewing of P. hirsutus (Cockerell). Scale bars = 1