Scaptotrigona (Scaptotrigona) grueteri Engel, 2022

Engel, Michael S., 2022, Notes on South American stingless bees of the genus Scaptotrigona (Hymenoptera: Apidae), Part IV: Four new species of group B from the Andean region, Journal of Melittology 2022 (112), pp. 1-13 : 11-13

Scaptotrigona (Scaptotrigona) grueteri Engel , new species

ZooBank: urn:lsid:zoobank.org:act:680C6411-FF1B-4662-9935-AD040C6C2F91

( Figs. 10–12 )

DIAGNOSIS: This species is superficially quite similar to S. semiflava (vide supra), but can be easily distinguished by the lack of extensive facial markings, the areas of yellow restricted to small circular patches near the upper clypeus ( Fig. 12 ), the more prevalent minute white pubescence of the lower face, clypeus, and supraclypeal area ( Fig. 12 ), and the denser punctation on the clypeal disc. Scaptotrigona grueteri occurs from 1700–2300 m and this may account for the generally darker coloration of the species. In addition, the wings of S. grueteri are less intensely colored than those of S. semiflava , the yellowish parchment tinge being noticeably lessened by comparison (cf. Figs. 7 , 10 ), and on average the malar space is typically shorter than that of S. semiflava , although they do overlap in lengths at the shorter end of the range for the later species.

DESCRIPTION: As described for S. anaulax (vide supra) except as follows: ⚲: Total body length approximately 5.3–5.6 mm, forewing length (to base of humeral sclerite) 6.0– 6.2 mm. Head wider than long, width 2.40–2.50 mm, length 1.90–2.00 mm; compound eye length 1.33–1.40 mm; upper interorbital distance 1.60–1.63 mm, lower interorbital distance 1.47–1.57 mm. Scape length 0.90–0.97 mm, slightly longer than torulocellar distance, torulocellar distance 0.83–0.87 mm. Clypeus length 0.63–0.67 mm, width 1.20–1.23 mm. Malar area long, length 1.6× flagellar diameter. Preoccipital carina strong, lamellate dorsally and bordered by deep medial indentation and modest lateral indentations, laterally carina broadly interrupted by deep concavity, lamella scarcely extending into concavity, lower angle of concavity projected upward as a short, acute projection (short genal tooth present).

Integument generally black to dark brown; labiomaxillary complex brown to yellow brown; labrum dark brown; mandible brown except darker proximally; clypeus brown; supraclypeal area brown to dark brown; malar space brown to dark brown; face below tangent of antennal toruli largely brown except with small semitranslucent or diaphanous yellow to yellowish brown spot bordering epistomal sulcus between anterior tentorial pit and lower outer margin of torulus, spot about as wide as torular diameter (sometimes spot is merely represented by thin area of lighter brown relative to bordering brown integument); scape dark brown except yellowish brown near base and sometimes brown on proximal half ventrally; pedicel and flagellum dark brown; remainder of face dark brown to black; vertex and posterior of head dark brown to black; gena dark brown; postgena dark brown except hypostomal borders yellow. Mesosoma black; tegula dark brown to black; legs dark brown to black except apex of apicalmost tarsomeres yellow to yellowish brown. Wing membranes hyaline and faintly yellowed, less so posteriorly; veins largely yellow except brownish along anterior margin. Metasoma dark brown to black except sometimes lighter on anterior-facing surface of tergum I, sterna somewhat lighter than terga.

Integument smooth and shining amid punctures; clypeus and supraclypeal area with minute, shallow punctures separated by a puncture width or less, although punctures sparse in lateral areas of clypeus and separated by less than a puncture width on supraclypeal area; lower face with punctures as on clypeus albeit sparser and sometimes larger, such punctures again minute on frons and separated by a puncture width or less except somewhat denser centrally and separated by up to 2× width toward ocellocular area; gena with minute punctures separated by a puncture width or typically much less; postgena impunctate and finely imbricate.

Fine pubescence generally consisting of minute to short, appressed or decumbent golden, pale yellow, or off-white setae. Pronotal lobe with dense, pale yellow to off-white, plumose setae; mesoscutum and mesoscutellum with scatered, minute, simple, subappressed to decumbent, golden to fuscous setae, mesoscutum without plumose setae anterolaterally and laterally; mesepisternum with short to long, erect to suberect, black to off-white setae, intermixed with black bristles, with short, off-white, plumose setae on upper part of hypoepimeral area; metepisternum with dense, off-white, plumose setae; propodeum lateral surface with setae similar to that of metepisternum. Legs with largely black setae, except coxae, trochanters, and proximally on femora with long, off-white to pale yellow setae. Metasomal terga with minute, appressed to decumbent, simple, fuscous setae, except anterior-facing surface of tergum I glabrous, tergum I without diffuse plumose setae, terga III–VI covered with dense, appressed to subappressed, bright yellow, plumose tomentum, such setae also on apical margin of tergum II as an apical fringe. Bristles, typically black, as follows: lateral surface of propodeum with long, erect, fuscous bristles arising amid off-white tomentum; legs with black bristles. Metasoma terga III–V with abundant, suberect to subdecumbent yellow bristles, sometimes a few bristles fuscous to black but yellow bristles dominate, similar yellow bristles longer and more erect on tergum VI, particularly along margin; tergum I without bristles, tergum II with some short fuscous bristles laterally.

♀: Latet.

♂: Latet.

HOLOTYPE: ⚲, Bolivia: La Paz, 9.4 km E Chulumani, Apa Apa Ecol. Reserve , 2100– 2300 m, 16°20.99’S, 67°30.30’W, 21-I-2001 [21 January 2001], J.S. Ashe, R.S. Hanley ( SEMC).

PARATYPES: 6⚲⚲, Bolivia: La Paz, 9.4 km E Chulumani, Apa Apa Ecol. Reserve , 2100–2300 m, 16°20.99’S, 67°30.30’W, 21-I-2001 [21 January 2001], J.S. Ashe, R.S. Hanley ( SEMC); 1 ⚲, Bolivia: La Paz, San Tacinto , 1700 m, 5/ 8 Dec 1955, L.E. Peña ( SEMC) .

ETYMOLOGY: The specific epithet honors Christoph Grüter for his considerable contributions to the biology of Meliponini and particularly his wonderful book on stingless bees ( Grüter, 2020).

Figures

Figures 10–12. Workers of Scaptotrigona (Scaptotrigona) grueteri, new species. 10. Lateral habitus. 11. Dorsal habitus. 12. Facial view.

Figures 7–9. Workers of Scaptotrigona (Scaptotrigona) semiflava, new species. 7. Lateral habitus. 8. Dorsal habitus. 9. Facial view.