Plectoplebeia, Melo, 2016

Melo, Gabriel A. R., 2016, Plectoplebeia, a new Neotropical genus of stingless bees (Hymenoptera: Apidae), Zoologia (e 20150153) 33 (1), pp. 1-8 : 2-5

Plectoplebeia gen. nov.

urn:lsid:zoobank.org:act:BFA974A0-1CA9-4CBE-A148-C1B5EDFB8800

Type species: Trigona nigrifacies Friese, 1900 .

Diagnosis and Comments. At a first glance, the type species of Plectoplebeia resembles just an enlarged Plebeia . The somewhat rounded head shape, a mostly smooth, shiny integument, a relatively short body pilosity and possession of a narrow depressed rim along the posterior margin of the inner surface of the hind tibia suggest a species of Plebeia . It differs from Plebeia by a larger body size, wider distance between the clypeus and the eye, coarser punctures on the head and mesosoma, a shorter, convex scutellum, a higher number of hamuli, and by an elongate metasoma, with an unusually long first tergum. While these features suggest Mourella and Schwarziana , Plectoplebeia lacks the long plumose body pilosity, the plumose sternal fimbria, and the modified hind tibia characteristic of these two genera. Unique features of Plectoplebeia include a shallow depression on the lower portion of the frons, the very short scutellum, the elongate propodeum and metapostnotum, the rectangular first segment of the metasoma, the elongate and sinuous hindtibia, and the long wings.

The type species of Plectoplebeia , Trigona nigrifacies , has had a brief, but convoluted taxonomic history. It was described by FRIESE (1900) from a single worker collected in Peru (“Callanga”). Friese refers it to Schwarziana quadripunctata (Lepeletier, 1836) , an indication that could have hinted on the identity of the taxon, but the brief and limited original description was not of much help in the subsequent recognition of the species. The taxon remained completely ignored for more than a century until its mention in CAMARGO & PEDRO (2007). Based on personal communication by Claus Rasmussen, who examined the type specimen ( Fig. 1 ), CAMARGO & PEDRO (2007: 572) attributed it to Plebeina Moure, 1961 , a stingless bee genus from the Afrotropical region, and excluded the taxon from the Neotropical fauna. Indeed, the type specimen bears a label from C. Eardley, dated from 2003, as “ Plebenia [sic] denoiti (Vachal) ” ( Fig. 1 ). Despite having examined and labeled the type specimen, EARDLEY (2004) does not mention it in his revision of the African stingless bees. Probably trusting Eardley’s identification as correct, C. Rasmussen also added a label, dated from 2007, to warn of the supposedly wrong locality data ( Fig. 1 ).

This mistaken interpretation of Friese’s species was probably triggered by where the type specimen has been placed in the ZMB collection. It has been curated under the name “ Trigona beccarii v. nigrifacies ”, a homonymous taxon described by FRIESE (1912) from Africa ( Fig.2 ), and likely was placed under this name by a past curator when organizing Friese’s collection following its incorporation to the ZMB. Indeed, under the name “ nigrifacies ”, referring to a stingless bee, a drawer label and catalog card have been made only for the African taxon in the ZMB collection, with the older name from South America being completely ignored. Of course, the peculiar features of this species do not suggest other better known groups of the Neotropical region and could easily mislead someone when doing a quick inspection. A new label indicating the type status was added, as well as a barcode label currently used in the ZMB for digitalization of the collection ( Fig. 1 ). The specimen has also been moved to a new position within the drawer.

As established below, Trigona (Plebeia) intermedia , a name proposed by WILLE (1960) for three workers from Bolivia, is considered a junior synonym of Friese’s Trigona nigrifacies . This synonymy is based on direct comparisons between type specimens, here illustrated in Figs. 3-11 .

Description. Worker. a) Body length about 5.5 to 6.0 mm. b) integument between punctures mostly smooth and shiny, fine rugulosity present on parts of head and mesosoma; metapostnotum with fine transverse rugulosity along basal portion and on middle of dorsal area, remainder finely areolate to reticulate. c) Body dark brown to black except for vestiture and markings described below; mesoscutum black; wing membrane light brown infumated. d) Yellow markings obscured on head, with most of mandible, broad stripe on mid of clypeus, lower parocular area and supraclypeal area dark reddish brown; on mesosoma, yellow markings as follows: a transverse stripe on pronotum, a spot on the pronotal lobe, one stripe on each side of mesoscutum, axilla, distal margin of scutellum, apex of fore femur and basis of all tibiae. e) Vestiture: erect hairs on body uniformly pale-yellow to light brown, darker on inner surface of tarsi, mostly simple, except on pronotal lobe, tegula, anterior margin of mesoscutum and along anterior portion of mesepisternum; in addition, with a fine shorter pilosity, covering the face, gena, mesoscutum, lateral mesepisternum, metepisternum and propodeum laterally, mostly erect, except for gena, mostly simple on clypeus and mesoscutum, and finely branched on remainder; metapostnotum glabrous; labial palpi with long, curled, simple setae; setae on metasomal sterna simple. f) Head ca. 1.2x wider than long, about as wide as mesosoma; maximum interorbital distance about 1.15x greater than length of eye; inner orbit of eye slightly convergent below, upper interorbital distance ca. 1.2x the lower distance; upper alveolar tangent at middle of face; vertex rounded, not forming post-ocellar carina; malar space moderate, approximately 5/8 of diameter of third flagellomere; preoccipital ridge indicated as a low carina on upper part of head, on lateral portion rounded; gena, at side view, about as wide as compound eye. g) Clypeus 2.0x wider than long, convex; epistomal suture, between subantennal sutures a widely open V; supraclypeal area lacking modifications, not forming a flange at each side; mid portion of lower frons, adjacent to antennal sockets, slightly depressed and forming a shallow scapal basin. h) Labrum normal. i) Mandible bidentate. j) Scape slightly longer than alveolo-ocellar distance and slightly narrower than diameter of third flagellomere; pedicel and third flagellomere, respectively, as wide as long. k) Pronotum short, ca. 0.6 x length of scutellum; anterior margin normal, not emarginate, bordered by a short translucent lamella. l) Scutellum short, 1.9x wider than long; posterior margin semicircular, when viewed from above leaving a narrow portion of the metanotum visible; surface weakly convex along its mid line; basal fovea lacking. m) Forewings longer than body length, ca. 3.0x length of hind tibia; pterostigma ca. 4.2 x longer than wide, 1.4x wider than diameter of third flagellomere; marginal cell ca. 3.8 x longer than wide, lanceolate, slightly open at apex; bifurcation between M and Cu coinciding with cu-anal vein; submarginal angle between Rs and Rs + M straight, ca. 90°; angle between M and Rs + M obtuse, ca. 120°; first abscissa of M ca. 0.9x length of first abscissa of Cu ; submarginal cells weakly veined, first r-m almost obsolete; hind wing with jugal lobe about as long as 0.44x vanal lobe length; hamuli 6 to 7. n) Hind tibia very long, ca. 2.8x longer than wide; anterior margin, in side view, forming a gentle curve; postero-distal edge slightly pointed; corbicula occupying distal half, gently depressed, more strongly concave at apex; corbicular setae simple, except for tuft on distal edge; internal surface with very wide keirotrichiate area, with a narrow posterior rim, glabrous, depressed, approximately 1/7 the greatest width of keirotrichiate area, depressed rim gradually becoming obsolete toward basis of tibia and lacking from basal quarter of tibia; tibial comb normal, penicillum covered externally by fine curled hairs. o) Hind basitarsus ca. 0.75x as wide as tibial width and ca. 0.6x its own length, apex 1.3x basal width; posterior margin sinuous, postero-distal edge projecting slightly, rounded; internal surface without basal sericeous area, hairs irregularly distributed. p) Metapostnotum conspicuously protuberant, slanted dorsal portion about 1.5x as long as posterior vertical portion in side view. q) Metasoma moderately elongate, approximately rectangular in dorsal view; tergum 1 about 0.75x as long as its maximum width. r) Labium normal, approximately 0.75x as long as head length; galea much shorter than length of hind tibia. s) Nest unknown.

Etymology. The new genus is named as a combination of plecto, from Latin meaning “weave, twine, twist”, with Plebeia , the name of the stingless bee genus which it resembles.

Figures

Figures 1-2. Plectoplebeia nigrifacies: (1) labels of the holotype of Trigona nigrifacies Friese, 1900; (2) place under which the holotype of T. nigrifacies was found in the ZMB collection.

Figures 3-7. Holotype worker of Trigona nigrifacies Friese, 1900: (3) habitus, side view; (4) head, frontal view; (5) head and mesosoma, dorsal view; (6) metasoma, dorsal view; (7) hind leg, side view.

Figures 8-11. Paratype worker of Trigona (Plebeia) intermedia Wille, 1960: (8) habitus, side view; (9) head, frontal view; (10) head and mesosoma, dorsal view; (11) specimen labels.