Epeolus niger
Creators: name: Onuferko, Thomas M.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Apidae
Epeolus
Epeolus niger

description: Epeolus niger (Michener, 1954)
Figs 1G, 5B, 7G, 15
Trophocleptria nigra Michener, 1954: 125 (♀).
Proposed common name
Black epeolus.
Diagnosis
Together with the morphological features that are diagnostic for the ‘ Trophocleptria group’, the following in combination can be used to tell E. niger apart from all other Epeolus: there is no large tooth laterally near the base of each axilla (Fig. 15D); the mesoscutellum does not have a pair of posteriorly directed teeth (Fig. 15D); the mesopleura are finely punctate, each with punctures more or less equally dense throughout (few i≥2d) (Fig. 5B); and the metasomal terga lack pale pubescence (Fig. 15 A–C). Epeolus niger most closely resembles E. claripennis in that both species are almost entirely black and at least the fore wings of females are deeply infuscate basally and (unusually for Epeolus) clear apically, but in E. claripennis there is a large tooth laterally near the base of each axilla, the mesoscutellum has a pair of posteriorly directed teeth and the mesopleura are more coarsely punctate, each with sparser punctures ventrolaterally (many i≥2d) than in the upper half, with interspaces dull due to tessellate surface microsculpture.
Material examined
Primary type material
PANAMA • ♀, Tro. nigra holotype; Chiriquí, El Volcán Chiriquí; 29 Feb. 1936; F.E. Lutz leg.; AMNH AMNH_IZC 00324260.
Secondary type material
PANAMA • 1 ♂, Tro. nigra allotype; Chiriquí, El Volcán Chiriquí; 23 Feb. 1936; F.E. Lutz leg.; AMNH AMNH_IZC 00324261.
DNA barcoded material with BIN-compliant sequences
Unavailable.
Non-barcoded material
COSTA RICA • 1 ♀; Alajuela, Alajuela? (Eladio’s, river trail); 19 May 1989; J. Ashe, R. Leschen and R. Brooks leg.; KUNHM SEMC1248345 • 3 ♀♀; Alajuela, Peñas Blancas; Apr. 1987; E. Cruz leg.; RAM • 1 ♂; Guanacaste, Volcan Cacao Station (Guanacaste National Park); 13 Feb. 1995; L.S. Kimsey leg.; UCBME.
Redescription
Female
MEASUREMENTS. Length 8.0 mm; head length 2.1 mm; head width 2.7 mm; fore wing length 8.1 mm.
INTEGUMENT COLORATION. Mostly dark brown to black; notable exceptions as follows: at least partially ferruginous on mandible, antenna, pronotal collar, tegula, mesopleuron and legs. Mandible with apex darker than rest of mandible; preapical tooth lighter than mandibular apex (difficult to see in holotype because mandibles closed; described from non-type specimen). Antenna brown except scape, pedicel and F1 extensively orange. Wing membrane subhyaline, basally dusky. Legs with brown or black more extensive than reddish orange.
PUBESCENCE. Face with tomentum densest around antennal socket. Clypeus, upper paraocular and frontal areas, and vertexal area mostly exposed. Pronotal collar with narrow band of ferruginous short, appressed setae along posterior margin. Mesoscutum with some ferruginous short, appressed setae along posterior margin. Mesopleuron nearly bare, except along margins. Metanotum with tomentum sparser medially, uniformly light brown/pale ferruginous. Dorsum of metasoma without bands of pale tomentum. T5 laterally with long, erect simple setae. T5 with pseudopygidial area lunate, its apex more than twice as wide as medial length, indicated by silvery setae on disc of apicomedial region elevated from rest of tergum. S5 with apical fimbria of coppery to silvery hairs extending beyond apex of sternum by ~½ MOD.
SURFACE SCULPTURE. Punctures dense. Labrum with larger and sparser punctures (many i≥1d) than clypeus (i<1d). Small impunctate dull/textured spot lateral to lateral ocellus. Mesoscutum, mesoscutellum and axilla very coarsely and densely rugose-punctate. Tegula densely punctate anteriorly and mesally (i≤1d), sparsely punctate (i>2d) to impunctate posteriorly and along margins. Mesopleuron with ventrolateral half densely punctate (i≤1d), interspaces dull due to tessellate surface microsculpture; mesopleuron with punctures more or less equally dense throughout. Metasomal terga with punctures very fine, dense (i≈1d), evenly distributed on disc.
STRUCTURE. Preapical tooth acute. Labral apex with pair of small denticles (separated by shallow concavity), each preceded by small, discrete longitudinal ridge. Frontal keel strongly raised. Frontal area with pair of discrete, sparsely punctate, granulose protrusions, each located near upper mesal margin of compound eye. Head dorsally with pair of protrusions, each located where upper genal area meets vertexal area. Vertexal area strongly convex in frontal view. Scape with greatest length 1.4 × greatest width. F2 noticeably longer than wide (L/W ratio = 1.4). Preoccipital ridge separated from hypostomal carina by no less than 1 MOD. Pronotal collar rather short (medial length ~⅔ MOD), expanded laterally to about 2 × medial length in dorsal view, and relatively straight along anterior margin. Mesoscutellum moderately bigibbous, depressed along posterior margin beneath overhanging ridge. Axilla large, its lateral margin more than half as long as mesoscutellar width (AL/MSCW ratio = 0.6) and tip extending as far back as apex of horizontal dorsal portion of mesoscutellum; axilla with tip conspicuously diverging from side of mesoscutellum, distinctly hooked, and axilla with free portion between ⅓ and 2 ∕ 5 its medial length; axilla with lateral margin relatively straight and carinate. Mesopleuron with weak carina delineating its anterior and lateral surfaces. Fore wing with three submarginal cells. Pygidial plate apically rounded.
Male
Description as for female except for usual secondary sexual characters and as follows: F2 shorter, not noticeably longer than wide (L/W ratio = 1.1); wing membrane dusky throughout; pygidial plate with larger and deeper punctures, closely punctate throughout; S4 and S5 with much longer (>1 MOD), curved coppery to silvery subapical hairs.
Distribution
Previously known only from Panama, herein newly reported from Costa Rica (Fig. 7G).
Ecology
Host records
Unknown.
Floral records
Unknown.
Remarks
Epeolus niger exhibits unusual sexual dimorphism in that in females the fore wings are only deeply infuscate basally, whereas in males the wings are infuscate throughout. The extensive black coloration and apically clear fore wings of this species and E. claripennis give both the distinctive appearance of Parachartergus. These features are also shared with various tropical stingless bees (e.g., Trigona spp.), some of which are known to be in mimetic complexes that include a diversity of aculeates, including other bees (Smith-Pardo 2005), and even non-hymenopterous insects such as flower flies (Diptera: Syrphidae) (Reemer 2013).
In addition to the examined material, this species is known from another four specimens from Panama (Michener 1954). Thus, E. niger appears to be uncommon, or at least uncommonly collected, compared to the similar-looking but much more widely distributed species E. claripennis. Based on known records, adults of E. niger are active between February and May.
description: Published as part of Onuferko, Thomas M., 2019, A review of the cleptoparasitic bee genus Epeolus Latreille, 1802 (Hymenoptera: Apidae) in the Caribbean, Central America and Mexico, pp. 1-69 in European Journal of Taxonomy 563 on pages 35-38, DOI: 10.5852/ejt.2019.563, http://zenodo.org/record/3476748