Epeolus diadematus, Onuferko, Thomas M., 2018

Onuferko, Thomas M., 2018, A revision of the cleptoparasitic bee genus Epeolus Latreille for Nearctic species, north of Mexico (Hymenoptera, Apidae), ZooKeys 755, pp. 1-185 : 63-68

19. Epeolus diadematus sp. n. Figs 41, 42, 92J

Epeolus torus Brumley, 1965. M.S. thesis, Utah State University, Logan 71 (♀) [nomen nudum].

Diagnosis.

Epeolus diadematus does not closely resemble any other species of Epeolus except E. chamaesarachae . Unique in the genus to both species are each of the following morphological features: the vertexal area has two pairs of shiny (usually impunctate) protrusions, the mesoscutum is distinctly ornamented with mostly separate patches of (but some intermixed) pale and ferruginous tomentum, and the T2 fascia has two pairs of anterolateral extensions of tomentum. The difference is that in E. diadematus the mesopleuron has denser punctures ventrolaterally (most i≤1d) whereas in E. chamaesarachae the mesopleuron has sparser (most i>1d) and fewer punctures ventrolaterally.

Description.

FEMALE: Length 6.9 mm; head length 2.0 mm; head width 2.6 mm; fore wing length 6.0 mm.

Integument coloration. Mostly black; notable exceptions as follows: partially to entirely ferruginous on mandible, antenna, pronotal collar, pronotal lobe, tegula, axilla, mesoscutellum, and legs. Mandible with apex darker than all but extreme base; preapical tooth lighter than mandibular apex. Antenna dark brown except scape, pedicel, and F1 brownish orange in part. Pronotal lobe and tegula pale ferruginous to amber. Wing membrane subhyaline, apically dusky. Legs more extensively reddish orange than brown or black.

Pubescence. Face with tomentum densest around antennal socket. Vertexal area with tomentum mostly ferruginous. Dorsum of mesosoma with bands of off-white and ferruginous short appressed setae. Dorsum of metasoma with bands of off-white to pale yellow short appressed setae. Pronotal collar with tomentum black medially, pale and ferruginous laterally. Mesoscutum with paramedian band of pale tomentum; ferruginous and pale tomentum encircling black spots medially and laterally, respectively, on anterior margin; and ferruginous tomentum along medial mesoscutal line and parapsidal line. Mesopleuron with upper half densely hairy, although scrobe visible; ventrolateral half nearly bare. Metanotum with tomentum uninterrupted, off white laterally and black medially. T1 with median diamond-shaped black discal patch enclosed by pale tomentum, except for medial separation at apex. T1 with apical fascia with black spot posterolaterally. T2-T4 with fasciae interrupted medially, T2 with fascia with paired anterolateral extensions of tomentum. T3 and T4 with fasciae interrupted laterally, with medial portion on apical margin and lateral portion encircling black tomentum on apical margin. T5 with two large patches of pale tomentum lateral to and separate from pseudopygidial area. 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 ~1/3 MOD.

Surface sculpture. Punctures dense, but those of head and mesosoma sparser in some areas, larger, deep, and distinct. Labrum mostly with larger and sparser punctures (i=1-2d) than clypeus (i≤1d). Upper paraocular area and vertexal area sparsely punctate (i=1-2d), the interspaces shining. Mesoscutum, mesoscutellum, and axilla coarsely and densely rugose-punctate; the interspaces shining. Tegula densely punctate mesally (i=1-2d), much less so laterally (i>2d). Mesopleuron with denser (i<1d) punctures in upper half than ventrolateral half, although ventrolateral half with most interspaces small (i≤1d); the interspaces shining. Metasomal terga with punctures very fine, dense (i≈1d), evenly distributed on disc.

Structure. Labral apex with two pairs of small denticles (the middlemost pair preceded by submedial pair of small denticles and separated by shallow concavity). Frontal keel strongly raised. Vertexal area with two pairs of nearly impunctate shiny protrusions. Scape with greatest length 1.6 × greatest width. F2 as long as wide (L/W ratio = 1.0). Preoccipital ridge not joining hypostomal carina, from which it is separated by no less than 1 MOD at its terminal. Mesoscutellum strongly bigibbous. Axilla intermediate in size, its lateral margin (L) nearly half as long as mesoscutellar width (W) (L/W ratio = 0.4-0.5) and tip not extending much beyond midlength of mesoscutellum (extending to <2/3 its length); axilla with tip conspicuously diverging from side of mesoscutellum, distinctly hooked, but unattached to mesoscutellum for less than 1/3 the medial length of axilla; axilla with lateral margin somewhat arcuate. Fore wing with three submarginal cells. Pygidial plate mostly hidden in holotype, but apically truncate in paratypes.

MALE: Description as for female except for usual secondary sexual characters and as follows: F2 shorter, nearly as long as wide (L/W ratio = 0.8); S4 and S5 with much longer coppery to silvery subapical hairs; pygidial plate apically rounded, with large deep punctures closely clustered apically and sparser basally, with the interspaces shining.

Etymology.

The name is in reference to the four shiny, usually impunctate, tubercles on the vertexal area of the head of this species. From the Latin, “diadema” (royal headband).

Distribution.

Texas and presumably Mexico, given the close proximity of some collection localities (e.g., Southmost, Texas) to the Mexico–United States border (Fig. 42).

Ecology.

HOST RECORDS: The host species of E. diadematus is/are presently unknown.

FLORAL RECORDS: The label of one examined voucher specimen indicates a floral association with Engelmannia pinnatifida A.Gray ex Nutt. ( Compositae ). This species has also been collected from Aphanostephus riddellii Torr. & A. Gray ( Compositae ) (J. Neff, personal communication, 2016).

Discussion.

This species and E. chamaesarachae are very similar in terms of integument coloration, pubescence, and structure, and are presumably sister species. Specimens of E. diadematus are distinct from those designated as E. chamaesarachae in that the mesopleuron has much denser punctation. The status of E. diadematus as a separate species is further supported by a separate BIN and large barcode sequence divergence (3.2%) from its nearest neighbor, E. chamaesarachae (Suppl. material 2). The ranges and flight seasons of these species also differ. With one exception, examined specimens of E. diadematus were collected in spring, and all are from Coastal or South Texas. By contrast, E. chamaesarachae occurs further west in the United States, and adults are active in late summer.

Material studied.

Type material. Primary: USA: Texas: McAllen Botanical Gardens (McAllen), 21.xi.1982, C. Porter (holotype ♀, FSCA).

Secondary: USA: Texas: 5 mi SE Realitos (27.3980°N; 98.5490°W) (Duval County), 22.iv.2005, J.L. Neff and A. Hook (paratype ♂, CTMI); Ben Bolt (Jim Wells County), 12.v.1952, M. Cazier, W. Gertsch, and R. Schrammel (paratype ♀, AMNH); Brackenridge Field Laboratory (Austin, Travis County), 28.iv.1989, A. Hook (paratype ♂, CTMI); Chaparral Wildlife Management Area (Dimmit County), 06.iv.2007, J.L. Neff and A. Hook (paratype ♂, CTMI), 11.iv.2003, J.L. Neff and A. Hook (paratype ♂, CTMI); Dallas, 22.v.??06, W.D. Pierce (paratypes 2♂, USNM); Galveston?, L. Packer (paratype ♀ [CCDB-30383 F06], PCYU); Southmost (Cameron County), 13.vi.1953, Univ. Kans. Mex. Expedition (allotype ♂, KUNHM).

DNA barcoded material with BIN-compliant sequences.

Available. BOLD:ADJ9659. See Type material for specimens examined and sequenced (indicated by unique CCDB-plate and well number).