Revision of the orchid bee subgenus Euglossella (Hymenoptera, Apidae), Part I, The decorata species group

Abstract Euglossella, one of the most distinctive subgenera of orchid bees of the genus Euglossa, is composed of two characteristic assemblages of species, one of them comprising bees bearing the strongly metallic integument trademark of the genus (viridis species group), and the other consisting of bees with a brown integument shaded with metallic iridescence (decorata species group). Here we provide the first of two parts of a revision of Euglossella, providing diagnostic definitions for the subgenus, the decorata species group, and all the species included therein. Six species are included in the decorata group, one new: Euglossa (Euglossella) aurantia, sp. n.; Euglossa (Euglossella) apiformis Schrottky, resurrected status; Euglossa (Euglossella) decorata Smith, revised status; Euglossa (Euglossella) singularis Mocsáry, revised status; Euglossa (Euglossella) cosmodora Hinojosa-Díaz and Engel; and Euglossa (Euglossella) perpulchra Moure and Schlindwein. Euglossa meliponoides Ducke and Euglossa urarina Hinojosa-Díaz and Engel are newly synonymized under Euglossa decorata, Euglossa decorata ruficauda Cockerell is synonymized under Euglossa singularis, and a neotype is designated for Euglossa apiformis.


Introduction
Among orchid bees of the genus Euglossa, one of the most distinctive groups are those species of the subgenusEuglossella, with their tridentate mandibles, lamellate pronotal dorsolateral angles, slender mesobasitarsi, truncate ventral margins of the metabasitarsi, and scalene triangular metatibiae. This subgeneric assemblage was originally established by Perty (1833) under the generic name Cnemidium, a homonym, but renamed and more truly characterized by Moure (1967) to encompass those Euglossa in which the males have tridentate mandibles. Dressler (1978b) reinterpreted the subgenus by considering additional characters, most of them secondary sexual features of the males, making it a more coherent taxonomic unit. Hinojosa-Díaz (2008), when discussing the male genitalic morphology across Euglossa, gave an account of features that further contributed to the cohesiveness of Euglossella as a subgenus. Recent phylogenetic analyses based both on external morphology (Hinojosa-Díaz 2010, in prep.) and molecular data (Ramírez et al. 2010), situate Euglossella as a monophylelic entity sister to all other Euglossa sensu lato, either alone (morphology) or in a clade together with the subgenus Dasystilbe (molecular). Within Euglossella a clear distinction can be traced to group the species in two easily recognizable species groups. The first includes all those species that, as is the rule for all other Euglossa outside of Euglossella, have strongly and brightly metallic body integument, which is those species resembling Euglossa (Euglossella) viridis (Perty), type species of the subgenus. The second species group includes species characterized by a distinctive yellow-brownish coloration with secondary iridescence on the head and mesosoma, and an almost complete absence of metallic color on the metasoma, and includes thosetaxa resembling E. (E.) decorata Smith. Besides the morphological distinction, the viridis species group has a wide Neotropical distribution, from southern Mexico to southern Brazil, while the decorata species group is restricted to South America East of the Andes, in areas surrounding the Amazon Basin. A taxonomic revision of the decorata species group is here presented as the first of two parts dedicated to the subgenus Euglossella. Diagnoses for each recognized taxon are provided, along with detailed descriptions for four species -one of them proposed as new and another resurrected from synonymy -and two others with clarified status.

Material and methods
Material examined in this study is deposited in the following collections: Division of Entomology, University of Kansas Natural History Museum, Lawrence, Kansas, USA (SEMC); Florida Museum of Natural History, University of Florida, Gainesville, Florida, USA(FLMNH); The Natural History Museum, London, United Kingdom (NHML); American Museum of Natural History, New York, New York, USA (AMNH); Museu Paraense Emílio Goeldi, Belém, Pará, Brazil (MPEG); Museu de Historia Natural, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil (BHMH); Hungarian Natural History Museum, Budapest, Hungary (HNHM); Departamento Diagnosis. Mid-sized metallic bees, with rather robust habitus; both sexes with tridentate mandibles and pronotal dorsolateral angles projected as acute prong or lamella (Fig. 3); female metabasitarsus trapezoidal with noticeably narrow distal margin (Figs 26,46,56,65,74); male mesotibia with two tufts, anterior tuft ellipsoidal, occupying about one-third of the outer tibial surface, posterior tuft rounded in a variety of shapes (Figs 24,44,54); male mesobasitarsus characteristically elongate and slender (Fig. 4), distal mesotarsomeres (specially second) unmodified; inner surface ofmale metafemur with ventral margin distinctively straight; male metatibia scalene triangular, metatibial organ slit basal and distal sections separated by a constriction distinctively narrower than width of contiguous basal section, basal section ellipsoidal, distal section separated from ventral margin of tibia by less than its own length (Fig. 6); ventral margin of inner metatibial surface with a blunt projection adjacent to spur attachment; male metabasitarsus roughly rectangular, ventral margin roughly straight in respect to sagittal body plane, appearing truncate and without noticeable projections of posterior margin. Eighth metasomal sternum of male with lateral edges of posterior section deeply invaginated, lobes strongly projected (Fig. 26); posterior margin of apical process of gonocoxite oblique (inner-posterior corner displaced posteriad) (Fig. 30); lateral area of gonostylar process of gonocoxite truncate; spatha surface with longitudinal striae (Fig. 30); dorsal sector of lateral section of gonostylus convex, covered with distinctive plumose setae, gonostylar ventral lobe thumb-like . Integument of entire body strongly and brightly metallic blue, green, purple or reddish (e.g., figure 2); tegula metallic (usually same color as mesoscutum), never completely translucent (sometimes translucent on margins);metasomal terga usually with dense strong punctation .................. viridis species group -Integument of head and mesosoma with a dominant basal brown to dark brown color, shaded by a varying degree of metallic iridescence, particularly green, cyan, and coppery; integument of metasoma varying from goldenorange to dark brown with very faint metallic hue or iridescence ( The decorata species group

Key to species groups of Euglossella
Recognition. The bees of the decorata species group are easily recognizable from other Euglossella species mainly based on their integumental coloration. Species of the decorata group,unlike all other Euglossa sensu lato, have brown as the base color of their head and mesosoma, tinged with iridescence to different degrees but on close observation the underlying brown coloration can be seen. This integumental color feature can be appreciated more easily as it is expressedon the tegula, which in these bees is characteristically hyaline with no metallic coloration on it beyond some faint hue. The legs and the metasoma are practically devoid of metallic coloration, and can be of any color between yellow and very dark brown, although as for the tegula, they can have some faint hue. This rather distinctive coloration makes the species of the decorata species group appear at first sight similar to species of the genus Melipona (Apinae, Meliponini Diagnosis. Labiomaxillary complex in repose reaching posterior tip of metasoma in the male (estimate), and posterior margin of third metasomal sternum in the female (Fig. 8, 10);integument of head of both sexes dark brown to black, with greencyan hue on frons and coppery hue on clypeus (Figs11-12); mesosoma dark brown with green hue; mesotibia with a noticeable convexity on proximal area of anterior mesotibial surface, along anterior margin of anterior setal tuft (Fig. 13); first and second metasomal terga orange-brown, turning brown on posterolateral margins; third to seventh terga mainly brown except orange-brown on anterior margin,coppery hue iridescence on all terga; sterna orange-brown (Figs 7-10);malar area length on average 0.25 the basal mandibular width; male mesotibial tufts appearing fused (except for a distal separation),posterior tuft teardrop shaped (Fig. 14); male metatibia scalene obtuse triangular (forming a clearly obtuse angle at intersection of anterior and ventral margins) (Fig. 15).
Coloration. Head mainly dark brown (except as described below), with green-cyan hue on frons and paraocular areas, mid-clypeus with coppery hue; paraocular ivory marks well developed, triangular, lower width one-half length of lower lateral parts of clypeus or slightly wider; lower lateral parts of clypeus ivory, amber-translucent at edge; labrum ivory; labral anterior and posterior edges as well as labral windows ambertranslucent; malar area brown on sides (condyle, acetabulum), ivory at center; mandible ivory on basal outer surface, teeth and ridges brown; antenna light brown; scape with ivory spot covering roughly all anterior surface (Fig. 11).Pronotum, mesoscutum and propodeum dark brown with strong green hue episternum dark brown with a combination of green and coppery hue, mesoscutellum orange-brown (Figs 7-8); legs brown, turning dark brown on mesotarsomeres, metatibia and metatarsomeres, all with faint coppery hue (Figs 7-8); tegulae and wing veins light amber, hyaline, with light coppery-golden hue. First and second metasomal terga orange-brown, turning brown on posterolateral margins; third to seventh terga mainly brown, except orangebrown on anterior margin (if visible); coppery hue iridescence on all terga, appearing coppery-golden on translucent posterior sections of first to sixth terga. (Fig. 7).Sterna orange-brown, fith and sixth sterna slightly darker, posterior sections of all sterna translucent; faint coppery hue on all sterna integument.
Sculpturing. Face areolate-punctate, with dense, strong areole-punctures, denser and slightly smaller (nearly one-fifth of median ocellar diameter) on frons; paraocular marks and lower lateral parts of clypeus less densely sculptured; vertex moderately areolate-punctate, smooth on anterior ocellar area; gena densely areolate-punctate, smooth on a narrow streak close to compound eye (except for scattered large punctures on upper margin). Mesosoma with round, moderately-dense punctures, as big as punctures on frons; punctures separated by about one half of a puncture diameter on mesoscutum and mesepisternum, contiguous and slightly bigger on mesoscutellum (specially towards posterior margin); metatibia moderately dense punctate on antero-proximal region (along anterior margin and postero-dorsal margin previous to metatibial organ slit), becoming gradually smooth towards posterior area, especially on surface near distal section of metatibial organ slit (Fig.15). Metasomal terga densely punctate (except smooth, polished on ventro-lateral sections and small antero-mesal surface of first tergum), puncture size comparable to that of frons punctures, increasing size ventrolaterally; metasomal sterna densely punctuate, punctures as big as ventro-lateral ones on terga, shallow, posterior margin of all sterna and contiguous areas to first sternum "false slits" smooth.
Vestiture. Facial setae of two kinds, some minutely branched (appearing simple), fulvous, long and sturdy, other plumose, rather fulvous, shorter and thinner. Frontal fringe with dense, fulvous, sturdy setae as long as about three mid-ocellus diameters, fulvous thin setae nearly two thirds as long as first; clypeus, supraclypeal area, and contiguous areas to clypeal disc moderately dense with an even combination of above described kinds of setae, both of about same length (about two median ocellar diameters); antennal depressions with moderately-dense, fulvous, plumose setae; paraocular marks, malar area, labrum and anterior surface of mandibles with scattered, fulvous, rather simple, short setae; vertex with scattered, fulvous, pectinate, minute setae around ocelli, interocellar area with a tuft of brown, sturdy setae; preoccipital ridge with a dense fringe comparable to the frontal one, but with brown, sturdy setae, as long as about four times median ocellar diameter; gena with dense, fulvous, plumose setae, short on upper section (where they intermix with similarly sized brown, simple, sturdy setae), increasing in length and becoming darker towards lower section, and continuing on outer mandibular margin where they become sparser, simpler and sturdier; antenna with fulvous, simple setae, long and scattered on scape, and dense and minute on flagellum. Prothorax with moderately dense fulvous, plumose, short setae; Mesoscutum, mesoscutellum and pronotal lobes covered with a combination of setae similar to that of frontal fringe, slightly longer and sturdier on pronotal lobes; mesepisternum densely covered with fulvous, plumose, long setae, becoming lighter on pleural and ventral areas; proximal podites (mainly coxae, trochanters, and part of femora) with setae as on ventral part of mesosoma; fulvous, simple, setae on femora (except as previously noted), tibiae (exceptions noted hereafter), and outer surface of tarsal articles; chemical gathering tufts on second through fourth protarsomeres made of dense, orange, long, setae; inner surfaces of probasitarsus, meso-and metatarsomeres with dense, brown, sturdy setae; mesotibia with two proximal tufts sitting on integumental concavities, anterior tuft ellipsoidal, occupying about one-third of outer tibial surface, posterior tuft teardrop shaped, slightly less than one-third as long as major axis of anterior tuft, laying on proximal posterior margin of anterior tuft, such that both tufts appear fused; both tufts made of fulvous setae directed posteriad, longer on anterior tuft (Fig. 14); microtrichia on outer mesotibial surface (velvety area) composed of dense, fulvous, simple, minute setae; anterior margin of velvety area strongly concave (Fig. 13); mesobasitarsus with three to four major wavy setae on inner surface right after proximal keel, all brown; metatibia with longer setae on anterior border and distal half of postero-dorsal margin, outer surface with scattered, brown, short, erect setae, bare on contiguous depression to metatibial organ; metatibial organ slit closed with brown setae (Fig. 15). First metasomal tergum with a mixture of setae comparable to those on posterior margin of mesoscutellum, but less dense, posterior half covered with moderately dense, fulvous, simple, minute appressed setae; second to seventh metasomal terga covered with scattered, dark brown, simple, sturdy setae as long as a median ocellar diameter, second through sixth metasomal terga with posterior bands of moderately dense, fulvous, appressed setae, as well as dense, fulvous, simple, long setal tufts on lateral margins; false slits of second metasomal sternum with tufts of moder-ately dense, fulvous, simple, long setae, directed posteriorly reaching posterior edge of sternum, remainder sterna with similar erect setae, mesially bare.
Terminalia. Genital capsule as described for subgenus. Lateral section of gonostylus with a straight dorsal sector.
Coloration. Generally as described for male, with a mixture of coppery and green hue on face and mesosoma. Paraocular marks absent; ivory coloration on mandible restricted to proximal one-third, antennal scape with thinner yellow spot occupying upper two thirds of antero-lateral surface (Fig. 16).
Sculpturing. As described for male except punctures of mesepisternum less dense. Vestiture. As described for male (setal features on protarsi, meso-and metatibia are exclusive of male) except as follows: Mesoscutellar tuft rhomboid, composed of dense, fulvous, erect, thick, multibranched (branches minute) setae (Fig. 19). Mesotibia with a streak of spur-like, dark brown setae on posterior and ventral edges; metatibial corbicula surrounded by long, dark brown setae. Mesial sections of all sterna nearly bare (where labiomaxillary complex resides when in repose).
Etymology. The specific epithet is a reference to the orange coloration of the metasoma in this bee species (Greek, aurantium, meaning "orange").
Comments. On initial observation the two specimens here included as type material for this species look very similar to individuals of E. decorata from the western Amazon Basin, particularly in coloration. However, aside from the generally more robust habitus of both the male and female by comparison to E. decorata, the dominant coppery iridescence of the clypeus is notably different, which, despite a range of variation in the latter, has a consistently dominant green coloration on the clypeus. Coloration alone is not necessarily a good indication of species boundaries, so the main character that distinguishes E. aurantia from any other species in the decorata group is the proximal convexity on the anterior surface of the male mesotibia along the anterior margin of the anterior mesotibial tuft (Fig. 13). Besides E. singularis, in which this mesotibial surface is straight, all other species have a slight deviation of the integument near the distal end of the anterior margin of the anterior mesotibial tuft, but this is only appreciable at higher magnification, and does not continue as a noticeable convexity along that margin. When looking at the mesotibia of the male of E. aurantia, the convexity in this area is immediately recognizable. Diagnosis. Labiomaxillary complex in repose slightly exceeding posterior tip of metasoma in the male, and posterior margin of second metasomal sternum in the female (Figs 18,20); integument in both sexes dark brown (noticeably metasoma), with coppery-cyan hue all over (especially on clypeus), legs brown, turning dark brown on metatibia and metatarsomeres (Figs 18,20); malar area length on average 0.25 the basal mandibular width; male mesotibial tufts appearing fused (except for a distal separation),posterior tuft teardrop shaped (Fig. 24); male metatibia scalene obtuse triangular (Fig. 25).
Sculpturing. As described for E. aurantia (vide supra). Vestiture.General vestiture as described for E. aurantia, except as follows: of two kinds of setae generally present all over body, minutely branched (rather simple or serrate), sturdier ones appear darker (dark brown) than plumose ones (fulvous).
Coloration. In general as described for male but with a stronger coppery-cyan hue on face and metasoma. Paraocular marks absent; ivory coloration on mandible restricted to proximal one-third, antennal scape with yellow spot occupying upper half of antero-lateral surface (Fig. 22).
Sculpturing. As described for male except mesepisternum with punctures not as dense (separated by about one puncture diameter).
Vestiture. As described for male except as follows: Mesoscutum and mesoscutellar vestiture dominated by fulvous thinner setae, although dark brown kind is still present; mesoscutellar tuft rhomboid, composed of dense, fulvous and brown, erect, thick, multibranched (branches minute) setae (Fig. 19). Mesotibia with a streak of spur-like, dark brown setae on posterior and ventral edges; metatibial corbicula surrounded by long, dark brown setae. Mesial sections of all sterna nearly bare.
Comments. Schrottky (1911) described E. apiformis from an unspecified number of females presumably from Marcapata, Cuzco, Peru (Rasmussen et al. 2010). The original description (Schrottky 1911) refers to a species in the E. decorata species group with a dark brown metasoma and a bronze-green mesosoma, besides other characters common to all species of the group. Although some specimens of E. decorata have a dark metasoma (see comments for E. decorata), it usually comes with a darker mesosoma altogether, and only some E. decorata specimens from the eastern Amazon Basin have similar coloration to the one described by Schrottky (1911) and observed in the specimens here examined. Characters not mentioned by Schrottky (1911) that distinguish this species from E. decorata (with which it shares some distributional range) include the coloration of the clypeus being more coppery than green, a labiomaxillary complex in the male extending slightly beyond the tip of the metasoma (not surpassing it in E. decorata), and a truncate posterior mesoscutellar margin (evenly convex in E. decorata). Euglossa apiformis appears as a synonym of E. singularis in the euglossine checklist of Moure (1967) and Kimsey and Dressler (1986), as well as in Moure et al. (2007) and Nemésio and Rasmussen (2011). This synonymy was most likely based on the assumption that any darker looking bee resembling E. decorata would correspond to E. singularis but as discussed later in this work this color distinction disregarded all other morphological evidence. The set of characters here presented and the locality records located in a continuous region along the lowlands contiguous to the Andes on the Amazon Basin of Peru and Ecuador justify the validity of the species. A neotype is here designated in order to validate the status of the species as described by Schrottky (1911) since the original type materialis presumed lost (Moure 1967, Kimsey and Dressler 1986, Moure et al. 2007, Rasmussen et al. 2009). The localities of the specimens here examined are in the same region and with similar elevations as the type locality (Schrottky 1911, Rasmussen et al. 2009). Although the original description was based solely on female characters, and therefore the original type corresponded to a female, a male is here designated as the neotype since males carry the most distinctive specific characters in Euglossa and designation of a female would carry the potential for further confusion in the future.  Diagnosis. Both sexes with labiomaxillary complex in repose reaching tip of metasoma, but not surpassing it (Figs 36,38,40); head integument brown (variable, see comments), with a varying degree of dominant green iridescence evident on clypeus (Fig. 41); integument of mesosoma colored as head, mesoscutellum partially (see comments) light brown with diminished iridescence (Figs 35,37,39); metasoma generally orange-brown, terga usually darker posteriorly, coppery-golden hue all over ; malar area length on average 0.20 the basal mandibular width; male mesotibial tufts appearing fused (except for a distal separation), posterior tuft teardrop shaped (Fig. 41); male metatibia scalene obtuse triangular (Fig. 45).
Sculpturing. As described for E. aurantia (vide supra). Vestiture. General vestiture as described for E. aurantia. Terminalia. Hidden sterna and capsule as described for E. apiformis, lateral section of gonostylus variable, ranging from flat dorsal sector to large projections (Figs 33, 34).
Coloration. In general as described for male but with a stronger coppery-cyan hue on face and metasoma. Paraocular marks absent; ivory coloration on mandible restricted to proximal one-third, antennal scape with yellow spot occupying most of antero-lateral surface although noticeably narrower than in male (Fig. 42).
Sculpturing. As described for male except mesepisternum with punctures not as dense (separated by about one puncture diameter).
Vestiture. As described for male (see comments); mesoscutellar tuft rhomboid, composed of dense, fulvous and/or brown (see comments), erect, thick, multibranched (branches minute) setae (Fig. 39). Mesotibia with a streak of spur-like, dark brown setae on posterior and ventral edges; metatibial corbicula surrounded by long, dark brown setae. Mesial sections of all sterna nearly bare.
Comments. Smith (1874) described E. decorata from a female labeled as from "S t . Paulo", and referred to its habitat as "St. Paulo (Brazil)". Moure (1967) referred to the type locality as São Paulo de Olivença in the state of Amazonas, Brazil, which was repeated in Moure et al. (2007) [it is well known that old uses of S. Paulo refer to a locality in the Amazon and not today's State or Municipality in southern Brazil: e.g., Papavero (1971)]. The majority of the specimens here examined are from the Amazon Basin, which agrees with the locality interpretation of the latter authors. Several of the distinctive features of the species are male features (as with most Euglossa s. lat.); however, the females are recognized also for the prevalence of green iridescence on the clypeus and the evenly convex mesoscutellar posterior margin. The original description of E. decorata var. ruficauda by Cockerell (1918) assumed the female holotype of that variety to be conspecific with E. decorata most likely based on coloration, which is in fact very similar in both specimens; however, as discussed later, E. decorata ruficauda is here synonymized with E. singularis. Euglossa meliponoides was synonymized with E. singularis both by Cockerell (1918) and by Moure (1967), most likely based on the dark coloration of the specimens used in the description of these two species; however, the male of E. meliponoides here examined and belonging to the type series exhibits the morphological features of E. decorata, notably the mesotibial posterior tuft of the male. Interestingly, Ducke (1902),when providing the original description of E. meliponoides, noted that his species wasvery likely just a dark variety of E. decorata, but proposed the name in the absence of intermediate specimens in terms of coloration. The surviving holotype is a female and provides no useful characters for identification beyond color. However, we examined the paratype male from the same collecting event which clearly demonstrates the taxon to be a synonym. Given that the male exhibits more useful characters it might be worth petitioning the ICZN to have Ducke's holotype set aside in favor of his male paratype, thereby even more strongly clarifying the status of the epithet meliponoides. Hinojosa-Díaz and Engel (2007) described E. urarina as a new species in the decorata group addressing particularities in the male genitalia, more specifically the lateral section of the male gonostylus having a prominent dorsal projection; otherwise the specimens used by those authors had external features just like any other male of E. decorata. As more specimens have been available for dissection of the genital capsule, it has come clear that the morphology of the lateral section of the gonostylus is highly variable in E. decorata, ranging from simple non-projected (besides the ventral lobe), to abruptly projected as seen in the specimens described as E. urarina (the same variation has been observed for E. apiformis). There is no pattern of covariation with other external characters in the male that indicates at the moment a possible species-specific morphology of the gonostylus. The same can be said in terms of coloration. There is a broad range of color variation across the specimens examined for E. decorata, most of them bearing the distinctive pattern of the holotype, with a rather golden-yellow to orange metasoma; however, all possible intermediates can be found between this and the very dark specimens from Loreto, Peru (Figs 37-38); specimens on the west range of the species seem to be darker, although not as dark as the Peruvian ones. It must be noted that wherever dark specimens occur there are also some light ones in the same habitat, and there is no major morphological difference among these. The extent of the lighter brown (turning yellowish) coloration on the mesoscutellum is also quite variable, some specimens having the whole mesoscutellum uniformly light brown or yellow (like the holotype), others having this coloration restricted to the marginal posterior edge. The vestiture color also exhibits a range of variation, correlated with the integumental coloration. The length of the labiomaxilalry complex in E. decorata reaches the tip of the metasoma, although some females, most notably the specimen here examined from Minas Gerais, Brazil have a noticeably shorten labiomaxillary complex. Given that we could find no further distinguishing evidence, it is assumed here that these females belong to E. decorata although we note that further review of new evidence could reveal largely cryptic species requiring recognition. Diagnosis. Labiomaxillary complex in repose barely reaching sixth metasomal sternum in the male, and posterior margin of third metasomal sternum in the female (Figs 48,50); both sexes with posterior margin of mesoscutellum evenly convex (Figs 47, 49); integument of head and mesosoma of both sexes brown to dark brown, with copperygreen hue, greener on mesoscutum (Figs 47-52); malar area length on average 0.15 the basal mandibular width; male mesotibia with posterior and anterior tufts separated by a distinguishable gap, posterior tuft characteristically circular (Fig. 54); male metatibia scalene right triangular (forming a right or slightly obtuse angle at intersection of anterior and ventral margins) (Fig. 55); first metasomal tergum orange, second tergum orange anteriorly, brown on posterior third, remaining terga brown to dark brown, similar pattern on sterna (some specimens, especially females with all metasoma dark brown), entire metasoma with faint coppery hue; legs yellow to dark brown (Figs 48,50,(53)(54)(55)(56); lateral section of gonostylus with dorsal sector straight, not projected, ventral lobe apically acute.
Sculpturing. As described for E. aurantia. Vestiture. General vestiture as described for E. aurantia. Terminalia. Hidden sterna and capsule as described for E. apiformis, lateral section of gonostylus with a straight or slightly convex dorsal sector (Fig. 33).
♀: Structure. Total body length 10.92 mm (10.00-11.63; n=5); labiomaxillary complex in repose reaching posterior margin of third metasomal sternum (Fig. 50 Coloration. In general as described for male. Paraocular marks absent; ivory coloration on mandible restricted to proximal one-third, antennal scape with yellow spot occupying most of antero-lateral surface although noticeably narrower than in male (Fig. 52).
Sculpturing. As described for male except mesepisternum with punctures not as dense (separated by about one puncture diameter).
Comments. Within the variety of specimens examined in the present study, most of those that exhibited a darker coloration deviating from the orangish color of the E. decorata type bore identification labels from several experts referring to them as E. singularis. As was noted above for E. decorata in which there is a range of color variation, including numerous intermediates, blending to very dark specimens, the same can be recognized for E. singularis. Despite the fewer number of specimens of E. singularis (as here recognized) available for this study, a similar (although not as extreme) variation of integumental coloration can be appreciated. The female holotype is the darkest of the specimens examined for this species, and the holotype of E. decorata ruficauda is the lightest. All specimens examined, both male and female, are on average smaller than any other species in the decorata group and the males are easily recognizable by the shape of the mesotibial posterior tuft. The rather copperyclypeus added to the previous features, and the restriction of these specimens to the Guiana Shield region, makes E. singularis a distinctive species, for which characterization should not rely solely on integumental color. Diagnosis. Labiomaxillary complex in repose slightly (but clearly) surpassing metasoma (both sexes) (Figs 58, 60); both sexes with head integument very dark (appearing black), with faint coppery hue on clypeus (mixed with some green-cyan higlights) (Fig. 61); integument of mesosoma with dark brown base and strong metallic olive-green, and coppery hue (especially on episternum); metasoma golden olive-green, with a noticeably dark brown band on anterior half of second metasomal tergum bordered anteriorly and posteriorly by yellow streaks (Figs 57, 59 ); malar area length on average 0.30 the basal mandibular width; male mesotibial tufts appearing fused (except for a distal separation),posterior tuft teardrop shaped (Fig. 63); male metatibia scalene slightly obtuse triangular (forming a slightly obtuse angle at intersection of anterior and ventral margins) (Fig. 64).

Euglossa (Euglossella) cosmodora
Comments. Given that a detailed description of both sexes was provided only recently by Hinojosa-Díaz and Engel (2007) and that we have no further modifications to that as presented in our earlier account, this material is not repeated here.
This species is quite distinctive, not only due to the banding pattern on the metasoma but also as it is the species withthe longest malar space of all taxa in the decorata species group. The specimen included herein from Bolivia extends the range of the species to the South, and is slightly lighter in coloration, although the exact locality data for this specimen is not clear (Tarata, Bolivia), the elevation of the two possible places with that locality name is clearly the highest (above 2000 m) for any specimen of this species group.  Diagnosis. Both sexes with labiomaxillary complex in repose nearly reaching metasomal posterior tip (estimation) (Figs 67, 69); integument of head very dark (appearing black) with strong coppery iridescence on clypeus, and green iridescence on frons (Figs 70-71); mesosoma dark brown (appearing black in most parts) with strong coppery iridescence intermixed with some cyan iridescence (Figs 66-69); metasoma dark brown (appearing black in some parts), all terga (except last) with posterior half noticeably translucent, forming a band pattern, all metasoma with cyan-coppery hue (Figs 66-69); malar area length on average 0.25 the basal mandibular width; male mesotibial tufts appearing fused (except for a distal separation), posterior tuft teardrop shaped (Fig. 72); male metatibia scalene slightly obtuse triangular (Fig. 73).
Comments. Given that a detailed description for the species has been published relatively recently (Moure and Schlindwein 2002), we have not repeated that material herein. The only additions needed are that the male terminalia, unfortunately not examined or discussed by Moure and Schlindwein (2002),are as described for E. apiformis in terms of the hidden sterna, while the genital capsule, and particularly the gonostylus, is as described for E. aurantia. The female was also not known at the time of the original description (Moure and Schlindwein 2002). We were able to examine two female specimens in the course of this study. The female exhibits basically the same features as the male (i.e., coloration, punctation, and vestiture), besides having antennae light-brown with a small yellowish spot on the upper anterior surface of the scape, and the regular features observed in other females of the species group (Figs 68-69, 71, 74).

Discussion
Prior to the the description of E. perpulchra and E. cosmodora (Moure and Schlindwein 2002;Hinojosa-Díaz and Engel 2007), this group of bees had been regarded as consisting of merely two species, vaguely separated by integumental coloration. Specimens with a generalized light color were assigned to E. decorata, while any specimen showing some darkening of the integument, mostly on the metasoma, was assigned to E. singularis. Two other dark colored forms -E. apiformis and E. meliponoides (Schrottky 1911;Ducke 1902) -were considered synonyms of E. singularis. Herein we reinterpret the group to include at least six distinctive species based on a combination of external characters that is concordant with distributional ranges. The scarcity of specimens for the group makes it likely that as more of them become available and additional characters are added, more species will be recognized. It is interesting to note the ranges of color and gonostylar variation within individual populations of some species, variations not correlated with each other nor with any other structural features. The maintenance of such variation might serve some function but it is entirely obscure at present. Population genetic studies on E. decorata and E. singularis would be fascinating, although the relative rarity of these bees is at present a hindrance to such work. It is possible that E. decorata is a broad-ranging species with considerable variation (as we have herein conceived) and that it has given rise to peripheral isolates which eventually formed the other species in the group [e.g., perhaps via modes similar to ones suggested by Mayr (1954Mayr ( , 1959 or Brown (1957)]. For the time being, we hope that this brief contribution will highlight what we believe to be congruent patterns among evolutionary species of the decorata group, and spur continued collection and field investigation into this highly unique lineage of Euglossella, and Euglossa as a whole. under their stewardship, to Andrés Lira for assistance with the map, and to two anonymous reviewers for their helpful comments. This is a contribution of the Division of Entomology, University of Kansas Natural History Museum.