Scaptotrigona magdalenae Engel, 2022

Engel, Michael S., 2022, Notes on South American stingless bees of the genus Scaptotrigona (Hymenoptera: Apidae), Part II: Subgroup A of the postica species group, Journal of Melittology 2022 (110), pp. 1-51 : 22-29

Scaptotrigona magdalenae Engel , new species

ZooBank: urn:lsid:zoobank.org:act:A8381269-236C-42AB-897A-5B2B10E21A04

( Figs. 29–43 , cover)

DIAGNOSIS: This is a smaller species of Scaptotrigona with mesoscutal striping currently known only from the Magdalena Valley, from Tolima to Cundinamarca. It is somewhat similar to the neighboring S. tatacoensis , but lacks the distinctive color patterns of that species (vide infra). While most Scaptotrigona have a faintly darker area at the apex of the marginal cell, usually merely a darkening of the background color of the wing membrane, this species has a more distinct infumate spot in this position, and appearing infused with black relative to the otherwise parchment color of the membrane ( Figs. 29 , 34 ). This is not a feature unique to the genus, but is distinctive among the subset of species in subgroup A of the postica group.

This species occurs in two distinct color morphs. Two years ago, I had originally considered each to be a distinct species as they originally seemed to be biogeographically distinct, albeit quite close to one another in the Magdalena River Valley. Given the small distances involved, that both were found together in a single collecting event at one locality, and that two individuals of the dark morph showed some progression toward the lighter morph, I ultimately concluded that they represent extremes of a range of variation within a single taxon. Thankfully, observations made last year by Victor H. Gonzalez clarified the mater as he was able to confirm that these are one cohesive species, as he collected both color forms from a single nest.

DESCRIPTION: As described for S. ederi (vide supra), with the following modifications: ⚲: Total body length approximately 5.2–5.9 mm, forewing length (to base of humeral sclerite) 5.0–6.0 mm. Head wider than long, width 2.33–2.42 mm, length 1.91–2.00 mm; compound eye length 1.33–1.39 mm; upper interorbital distance 1.53–1.55 mm, lower interorbital distance 1.42–1.52 mm. Scape length 0.88–0.91 mm, about as long as torulocellar distance, torulocellar distance 0.85–0.88 mm. Clypeus approximately 1.65–1.8× as wide as long, length 0.64–0.67 mm, width 1.06–1.21 mm. Malar area approximately 1.8× flagellar diameter or 0.80–0.82× basal mandibular width. Preoccipital ridge carinate, lamellate dorsally, with bordering medial and lateral indentations comparatively deep, carina interrupted laterally by deep concavity, lower margin of concavity with carina forming acutely rounded angle, slightly projecting upward as a short lamellate tooth, upper margin with preoccipital lamella extending into concavity about half length, sometimes less.

Light morph. Integument of labiomaxillary complex orange except prementum brown; labrum orange; mandible orange to reddish orange apically; clypeus orange, epistomal sulcus well delineated by orange brown to black; supraclypeal area orange; malar space orange; face below and above tangent of antennal toruli orange except reddish brown to black around ocelli and extending slightly onto upper frons, such marking not extending to orbits and sometimes medially divided by thin strip of orange from frons to median ocellus; scape orange, sometimes with brown dorsoapically; pedicel and flagellum typically dark brown above, with narrow underside of flagellum orange to light brown; vertex and posterior of head orange except for marking around ocelli; gena and postgena orange, hypostomal borders yellow. Mesosoma largely orange except mesoscutum black with orange along lateral borders and reddish brown to reddish orange strips from notauli to reddish orange posterior border, and mesepisternum with reddish brown to dark brown area anteroventrally; tegula wholly orange and semi-translucent; legs wholly orange except lighter on corbicula and tarsi. Wing membranes hyaline clear posteriorly to lightly parchment colored anteriorly, with lightly infumate area at marginal cell apex; veins orange. Metasoma generally yellow orange to orange, with tergal discs largely yellow except brown to dark brown laterally on terga I and II, and at extreme base of tergum II; terga III – V with brown to dark brown at extreme bases, often obscured by overhanging tergal margins; tergum VI brown basally and light brown to yellow apically; sterna yellow orange to orange.

Fine pubescence generally consisting of scatered, minute to short, appressed or decumbent yellow setae, such setae often simple but sometimes with minute branches or plumose, such plumose setae sometimes blending to yellow or pale yellow when dense around pronotal lobe, and on metepisternum and lateral surface of propodeum; sterna II– V with scopa composed elongate, erect, simple setae with characteristically wavy apices, such scopal setae yellow. Bristles as follow: Labrum with sparse, erect, simple, yellow bristles; vertex with numerous erect, simple, yellow to sometimes light fulvous bristles; pronotal dorsolateral margin near and anterior to pronotal lobe with yellow to fulvous bristles; mesoscutum with anterior and lateral borders with erect bristles, those on lateral border short, bristles largely yellow to fulvous, although along anterior margin some with dark fuscous bases and some entirely black bristles anterolaterally; tegula with short, suberect, yellow bristles anteriorly; mesoscutellum with abundant, elongate, erect, yellow to light fulvous bristles; mesepisternum with scattered, yellow to fulvous bristles, along rounded anterior border with preëpisternum a line of abundant, suberect yellow to fulvous bristles extending ventrally from pronotal lobe; lateral surface of propodeum with scatered, long, erect, yellow to light fulvous bristles. Legs with abundant yellow to fulvous bristles except some black bristles on prolateral surface of protibia, abundant on prolateral surfaces of mesotibia, pro- and mesobasitarsus, and apically on metafemur; metatibia and metabasitarsus with black bristles. Metasoma with numerous, prominent, suberect to subdecumbent, light fulvous to sometimes yellow bristles on terga III – V arising amid tomentum.

Dark morph. As for the light morph except as follows: upper two-thirds of frons dark brown to black, except often separated from inner orbit by thin strip of orange, rarely by broader strip that then extends into ocellocular area; vertex, posterior of head, and uppermost gena dark brown to black. Mesosoma largely dark brown to black except pronotal lobe, mesoscutellum, metanotum, and hypoepimeral area orange. Legs largely orange except prolateral surfaces of tibiae and upper surfaces of femora, except at joints reddish brown to brown. Metasoma generally dark brown to black except anterior-facing surface of tergum I brown, dorsal-facing surface of tergum I with orange brown apically and terga II– V with yellow apical marginal zones; tergum VI brown to dark brown; sterna brown to dark brown.

♀: Latet.

♂: As described for worker except as follows: Total body length approximately 5.5–6.0 mm, forewing length (to base of humeral sclerite) 5.6–5.8 mm. Head wider than long, width 2.24–2.30 mm, length 1.85–1.88 mm; compound eye length 1.48 mm; upper interorbital distance 1.30–1.36 mm, lower interorbital distance 0.97–1.06 mm. Scape length 0.61–0.67 mm, much shorter than torulocellar distance, torulocellar distance 0.76–0.79 mm. Clypeus approximately 1.39–1.44× as wide as long, length 0.67–0.70 mm, width 0.97 mm. Malar area approximately 0.8× flagellar diameter or 0.4× basal mandibular width. Gena narrower than compound eye. Preoccipital ridge weakly carinate dorsally, sharply angled at best laterally, without concavity or bordering indentations. Terminalia in figures 40–43.

Integument of labiomaxillary complex yellow to orange except prementum brown; labrum yellow to orange; mandible yellow to orange with reddish orange apically; clypeus yellow to orange, epistomal sulcus well delineated by dark brown to black; supraclypeal area yellow to orange; malar space yellow to orange; face below tangent of antennal toruli yellow to orange; frons largely brown to black except in broad yellow to orange triangular areas continuing from lower face on lower frons, such coloration extending as thin line along inner orbit to summit, sometimes with a small spot of yellow to orange anterior to median ocellus; vertex and posterior of head dark brown to black, uppermost margin of gena brown to black, remainder yellow to orange; postgena yellow to orange; scape orange; pedicel and flagellum typically brown to dark brown, flagellum lighter beneath. Mesosoma largely yellow to orange except mesoscutum black, sometimes with weak orange to reddish orange along lateral borders, mesepisternum with dark brown to black ventrally, sometimes more restricted posteroventrally or even with mesepisternum largely black with orange to reddish orange posterodorsally; metepisternum sometimes dark brown to black; metanotum sometimes dark brown; mesoscutellum sometimes more reddish orange to reddish brown and lighter medioapically; propodeum dark brown to black; tegula wholly orange and semi-translucent; legs entirely yellow orange to orange except in darker forms with spots of dark brown to black on protibia, prolateral surface of meso- and metabasitarsi entirely dark brown to black, and metatibia with line of dark brown to black on superior margin of prolateral surface in apical two-thirds. Metasoma generally yellow orange to black, either with terga dark brown to black with tergum I and tergum II to varying degrees broadly orange, tergum VII apically yellow, and sterna largely yellow brown, or in lighter individuals terga largely yellow to orange, with areas of brown to dark brown laterally on tergum I, basally and laterally on terga II– V, with tergum VI largely brown and tergum VII yellow.

Appressed, simple, short, yellow setae of mesoscutum more abundant and more transversely directed; sterna without scopal setae as in worker but with dense, subdecumbent to decumbent, mesial-posteriorly directed, simple, elongate, yellow setae. Bristles as follow: bristles of drone generally more elongate than those of worker; e.g., bristles of vertex much more elongate than in worker, and gently arched. Legs with abundant yellow to fulvous bristles except numerous black bristles on prolateral surface of pro- and mesotibiae and pro- and mesobasitarsi; such black bristles apically on metafemur; black bristles dominant and scatered over prolateral surface of metatibia; a few on prolateral surface and dominant on superior margin of metabasitarsus.

HOLOTYPE: ⚲, Colombia: Cundinamarca, Boqueron, El cruce a Pandi , 21-XII- 2011, 460 m, 4°15.601’N, 74°32.726’W, V. H. Gonzalez [light morph] ( SEMC).

PARATYPES: 32♂♂, Colombia: Cundinamarca, Boqueron, El cruce a Pandi, 21-XII- 2011, 460 m, 4°15.601’N, 74°32.726’W, V.H. Gonzalez ( SEMC). Dark morph. 4⚲⚲, Colombia: Cundinamarca, Boqueron, El cruce a Pandi, 21-XII- 2011, 460 m, 4°15.601’N, 74°32.726’W, V. H. Gonzalez ( SEMC). Light morph. 6⚲⚲, Colombia: Cundinamarca, Boqueron, El cruce a Pandi, 21-XII- 2011, 460 m, 4°15.601’N, 74°32.726’W, V.H. Gonzalez ( SEMC); 15⚲⚲, Colombia: Tolima, El Guamo Vereda Chontaduro, La Guaraperia, 337 m, 4°0.3662’N, 74°56.958’W, 21-XII-2011, V.H. Gonzalez ( SEMC) .

ADDITIONAL MATERIAL (each series from a different nest): 6⚲⚲ [dark], 3⚲⚲ [light] [from same nest], Colombia, Cundinamarca, San Antonio de Tequendama , 4˚38.107’N, 74˚21.331’W, 1581 m, 13 March 2021, V. H. Gonzalez [examined three managed hives] ( SEMC); 4⚲⚲ [light], 1⚲ [dark], Colombia, Cundinamarca, Beltrán , 4˚48.020’N, 74˚44.394’W, 237 m, 21 Feb 2021, V. H. Gonzalez ( SEMC); 4⚲⚲ [light], Colombia, Cundinamarca, Beltrán , 4˚48.020’N, 74˚44.394’W, 237 m, 21 Feb 2021, V. H. Gonzalez ( SEMC); 2⚲⚲ [light], Colombia, Cundinamarca, Beltrán , 4˚48.020’N, 74˚44.394’W, 237 m, 21 Feb 2021, V. H. Gonzalez ( SEMC); 2⚲⚲ [light], 1⚲ [dark], Colombia, Cundinamarca, Beltrán , 4˚48.020’N, 74˚44.394’W, 237 m, 28 March 2021, V. H. Gonzalez ( SEMC); 4⚲⚲ [dark], Colombia, Cundinamarca, Beltrán , 4˚48.020’N, 74˚44.394’W, 237 m, 30 March 2021, V. H. Gonzalez ( SEMC); 9⚲⚲ [dark], Colombia, Cundinamarca, Beltrán , 4˚48.020’N, 74˚44.394’W, 237 m, 30 March 2021, V. H. Gonzalez ( SEMC) .

ETYMOLOGY: The specific epithet refers to the Magdalena River Valley and the occurrence of the species in area around the joining of the Saldaña River with the Magdalena River and northward. The name is formed of Magdalena and the Latin suffix – us (– ae, feminine genitive singular; – i, masculine genitive singular), which forms adjectives from nouns and is used for commemoration and dedication.

COMMENTS: Victor H. Gonzalez examined several managed nests of this species in Cundinamarca and made the following observations, which he has kindly shared with me: In Beltrán, I found nests inside living trees of Albizia guachapele (Kunth) Dugand ( Fabales : Fabaceae : Caesalpinioideae: Mimosoid clade: Acacia clade: Ingeae grade; local common name: Igua), Pithecellobium duce (Roxb.) Benth. ( Fabales : Fabaceae : Caesalpinioideae: Mimosoid clade: Acacia clade: Pithecellobium group; local common name: Payandé), and Astronium graveolens Jacq. ( Sapindales : Anacardiaceae : Anacardioideae; locally known as Diomate). Nests are found from ground level to up to 12 m above ground. The nest entrance is a tube of brown wax of 2.5–3.0 cm long and a diameter of 12 mm × 8 mm. According to our local informant, bees are known as “enreda” — literally, “entangle” — because the bees are quite defensive and they get into people’s hair. Honey is sometimes used for human consumption (Gonzalez, in literis).

Figures

Figures 29–31. Worker of Scaptotrigona magdalenae, new species, light morph. 29. Lateral habi- tus. 30. Dorsal habitus. 31. Facial view.

Figures 32–33. Worker of Scaptotrigona magdalenae, new species, light morph. 32. Dorsal view of vertex and mesosoma. 33. Prolateral surface of metatibia, metatarsus, and metapretarsus.

Figures 34–36. Worker of Scaptotrigona magdalenae, new species, dark morph. 34. Lateral habi- tus. 35. Dorsal habitus. 36. Facial view.

Figures 37–39. Drone of Scaptotrigona magdalenae, new species. 37. Lateral habitus. 38. Dorsal habitus. 39. Facial view.

Figures 40–43. Male terminalia of Scaptotrigona magdalenae, new species. 40. Sternum VI. 41. Sternum VII. 42. Sternum VIII. 43. Genital capsule, left is dorsal view, right is ventral view.