Epeolus emiliae Onuferko, 2022

Onuferko, Thomas M. & Sheffield, Cory S., 2022, A new species of Epeolus Latreille, 1802 (Hymenoptera: Apidae) from western North America, Insecta Mundi 2022 (940), pp. 1-12 : 3-10

Epeolus emiliae Onuferko and Sheffield, new species

( Fig. 1 , 2B , 3B , 4B , 5–9 )

Proposed common name. Emilia’s epeolus.

Etymology. The specific epithet honors the primary author’s daughter, Emilia V. Onuferko. The noun is feminine and declined in the genitive case.

Materials examined. Primary type material. CANADA: British Columbia: ♂, holotype ( Fig. 1D ), OkanaganSimilkameen (49.5406° N, 119.5732° W), 27.viii–08.ix.2015, ex blue vane trap, D. Marks and J. Heron leg. ( RSKM RSKM _ENT_E-191681).

Secondary type material. CANADA: British Columbia: 1 ♂, paratype, Kelowna ( Quails’ Gate Winery ) (49.8385° N, 119.5712°W), 31.viii–24.ix.2016, ex blue vane trap, C. Dawson and J. Heron leg. ( RSKM RSKM _ ENT_E-191679) ; 1 ♂, paratype, Okanagan-Similkameen (49.5406° N, 119.5732° W), 27.viii–08.ix.2015, ex blue vane trap, D. Marks and J. Heron leg. (BOLD sample ID: CCDB-25139 G09, RSKM RSKM _ENT_E-185215) ; 1 ♂, paratype ( Fig. 1C ), Vernon , 15.ix.1919, E.R. Buckell ( CNC 719832 ) . USA: California: 1 ♀, paratype, 2 mi SW of Sugar Loaf Mountain , Modoc County, 12.ix.1969, E.E. Grissell and R.F. Denno leg. ( UCBME P 0219060 ) ; Colorado: 1 ♀, allotype ( Fig. 1A–B ), Grand Junction , “9-6-32”, L.G. Davis leg. ( CSUC) ; Idaho: 1 ♂, paratype, Massacre Rocks State Park , Power County, 16.ix.1955, W.F. Barr leg. ( USNM) ; Oregon: 1 ♀, paratype, Echo , 15.v.1904, E.S.G. Titus leg. ( USNM) .

Non-preserved material. USA: Washington: 1 ♀, 619 Tanglewood Dr., Richland (46.2722°N, 119.3112°W), 17.x.2021, L. Hill leg. (iNaturalist (https://www.inaturalist.org) record #98573666).

Diagnosis. The following morphological features in combination can be used to tell E. emiliae apart from all other North American Epeolus : the axillae are large, each with the tip extending well beyond the midlength of the mesoscutellum but not as far back as its posterior margin, and dilated laterally ( Fig. 2B ); the axillae (except sometimes the tips) and mesoscutellum are black ( Fig. 2B ); the mesopleura are closely (i≤1d) and evenly punctate; the T1 discal patch is wide but the lateral longitudinal band on each side is at least (and usually more than) half as wide as the breadth of the apical fascia in dorsal view ( Fig. 1B, D , 3B ); T1–T4 (in females) or T1–T6 (in males) have complete fasciae that reach or are very little removed from the apical margins of the terga ( Fig. 1B, D , 3B ); and the T2 fascia has a pair of anterolateral extensions ( Fig. 1 , 3B ). Epeolus emiliae is most similar to E. autumnalis ,

ertson, 1902 (green) and E. emiliae new species (orange) based on occurrence records known to the authors (yellow circles).

with the above features related to surface sculpture and structure shared between the two species. However, in E. autumnalis the axillae, including the tips, are invariably black ( Fig. 2A ); the legs, at least from the coxae to femora, are partially to predominantly dark brown/black ( Fig. 3A ) (they are entirely reddish orange from the femora to tarsi in E. emiliae , as shown in Fig. 1 , 3B ); the T1 discal patch is so wide that the lateral longitudinal band is barely visible in dorsal view ( Fig. 3A ); the T1–T3 apical fasciae are commonly narrowed or narrowly interrupted medially (although sometimes evenly broad) and at least somewhat removed from the apical margins of the terga ( Fig. 3A ); the T2 fascia does not have anterolateral extensions ( Fig. 3A ); and T5 of the female has a pair of large patches of pale tomentum surrounding the pseudopygidial area ( Fig. 4A ) (there is a single large, continuous patch of pale tomentum (or fascia) surrounding the pseudopygidial area in E. emiliae , as shown in Fig. 4B ).

Description. Male. Measurements. Length 9.2 mm; head length 2.2 mm; head width 2.9 mm; fore wing length 6.7 mm.

Integument coloration. Dark brown to black except as follows. Mandible, including preapical (almost submedial) tooth but excluding usual large apical tooth (rutellum) and extreme base (difficult to see in holotype because mandibles closed; described from paratype); labrum; pronotal lobe; tegula; coxae partially; trochanters partially to entirely; and femora to tarsi entirely reddish orange. Antenna entirely dark brown in holotype, but scape and F1 reddish orange in part in multiple paratypes. Axilla entirely black in holotype, but with tip reddish orange in multiple paratypes. Wing membrane dusky subhyaline, slightly darker beyond venation.

Pubescence. Face with tomentum densest around antennal socket. Tomentum slightly sparser on clypeus; upper paraocular and frontal areas and vertexal area mostly exposed. Dorsum of mesosoma and metasoma with bands of offwhite to pale-yellow short, appressed setae. Mesoscutum with paramedian band. Mesopleuron densely hairy, except for two sparsely hairy patches (one beneath base of fore wing (hypoepimeral area) and larger circular patch occupying much of ventrolateral half of mesopleuron). Metanotum with tomentum uninterrupted, uniformly pale yellow. T1 with discal patch umbrella-shaped and not especially wide—lateral longitudinal band at least half as wide as breadth of apical fascia in dorsal view. T1 with basal and apical fasciae and T2–T6 with apical fasciae complete, T2 fascia with pair of basomedially convergent anterolateral extensions. S4 and S5 with long (>1 MOD), curved, coppery to silvery subapical hairs.

Surface sculpture. Labrum with sparser punctures (i=1–2d) than clypeus (i<1d). Small impunctate dull/textured spot laterad lateral ocellus. Mesoscutum, mesoscutellum, and axilla coarsely and densely rugose-punctate. Tegula densely punctate mesally (i≤1d), less so laterally (i=1–2d). Mesopleuron with ventrolateral half densely punctate (i≤1d), interspaces shining; mesopleuron with punctures similar in size and more or less equally dense throughout. Metasomal terga with punctures very fine, dense (i≤1d), evenly distributed on disc. Pygidial plate with large deep punctures closely clustered, except along margins.

Structure. Preapical mandibular tooth inconspicuous, blunt and obtuse. Labral apex with pair of small denticles (separated by shallow concavity), each preceded by longitudinal carina. Frontal keel not strongly raised. Scape (excluding radicle) with greatest length 1.8× greatest width. F2 noticeably longer than wide (L/W ratio = 1.3). Preoccipital ridge separated from hypostomal carina below by about 1.0–1.5 MOD. Mesoscutellum weakly bigibbous. Axilla large, its lateral margin half as long as mesoscutellar width (AL/MSCW ratio = 0.5) and tip extending well beyond midlength, but not as far back as posterior margin, of mesoscutellum, tip distinctly pointed, but mesally unattached to emiliae new species (BOLD sample ID: CCDB-25139 G09, RSKM RSKM_

ENT_E-185215) (with posterior ends oriented toward the top).

mesoscutellum for less than 2⁄5 medial length of axilla; axilla with lateral margin arcuate and carinate. Fore wing with three submarginal cells (second submarginal crossvein incomplete in left fore wing of one (female) paratype, and second and third submarginal crossveins present but greatly reduced in both fore wings of one (male) paratype). Pygidial plate apically rounded.

Female. F2 longer than wide (L/W ratio = 1.5); T5 with large, continuous patch of pale tomentum (or fascia) bordering and contacting pseudopygidial area; T5 with pseudopygidial area lunate, its apex less than twice as wide as medial length, indicated by silvery setae on impressed disc of apicomedial region elevated from rest of tergum; T6 not fasciate; pygidial plate apically truncate, with smaller punctures; S4 and S5 with much shorter hairs (S5 with apical fimbria of coppery to silvery hairs extending beyond apex of sternum by ~1/3 MOD).

Distribution. United States west of the Great Plains to southern British Columbia ( Fig. 5 ).

Ecology. Host records. Unknown.

Floral records. Heterotheca villosa (Pursh) Shinners (Asteraceae) ( Fig. 6 ).

Remarks. Epeolus emiliae shares a BIN (i.e., BOLD:AAF2361) with E. autumnalis , its presumed sister species. The available DNA barcode sequence for E. emiliae exhibits as much as 99.5% similarity to sequences of E. autumnalis (determined using the BOLD Identification Engine: https://www.boldsystems.org/index.php/IDS_ OpenIdEngine) and does not cluster separately from them (see Fig. 7 ), suggesting conspecificity, albeit due to the inclusion of a short sequence (366 bp) of E. autumnalis in the NJ tree. The (male) specimen (BOLD sample ID: sheffT-53) with which the 366-bp sequence is associated agrees fully with the current morphological diagnosis for E. autumnalis ( Onuferko 2018) . Despite the short sequence’s position in the NJ tree, which should be interpreted cautiously (see https://www.boldsystems.org/index.php/resources/boldfaq#reg6), it is matched with 100% similarity to the nine (out of ten) BIN-compliant sequences presently available for E. autumnalis and has no unique nucleotides. By contrast, the only sequence available for E. emiliae has five nucleotides (40 – T; 235 – T; 262 – A; 634 – C; 637 – A) that are not shared with any sequences of E. autumnalis , although to determine whether or not they are diagnostic will require barcoding additional representatives of E. emiliae . In any case, the presence of multiple consistent and pronounced morphological differences in integument coloration and the patterns of pubescence on the metasoma as well as the apparent lack of range overlap between the two forms sharing this BIN support their treatment as separate species.

The male hidden sterna of E. emiliae ( Fig. 8 ) closely resemble those of E. autumnalis (see Onuferko 2017: pl. 2C), although there is generally little variation in the form of S7 and S8 among species of Epeolus . The genitalia are also very similar between the two species (see Fig. 9 ; Onuferko 2017: pl. 3C), and, as in most species of Epeolus (see Onuferko et al. 2019), in both E. autumnalis and E. emiliae the penis has a pair of fleshy lateral lobes.

This discovery presents yet another example of a case of speciation within Epeolus attributed to an east–west divide in North America. A plurality of sister species/clades of North American Epeolus with disjunct distributions are separated by the Great Plains and/or Rocky Mountains, which represent significant (modern and historical) barriers to gene flow ( Onuferko et al. 2019).

Although distinct from E. autumnalis , to confirm that the western form constituted an undescribed species, comparisons were made to descriptions and images of primary types (if available) of North American Epeolini with unplaced names. The list includes Triepeolus cuneatus Cockerell, 1917 , Triepeolus hopkinsi Cockerell, 1905 , Triepeolus isocomae Cockerell, 1904 , Triepeolus pomonalis Cockerell, 1916 , Epeolus scelestus var. tubercularis Brues, 1903 , and Triepeolus sequior Cockerell, 1921 , whose placement within Triepeolus Robertson, 1901 , remains unconfirmed ( Rightmyer 2008). The possibility that the species resembling E. autumnalis was described previously under any of these unplaced names was ruled out on the basis of pronounced morphological differences as follows.

In the (male) holotype of T. cuneatus (USNM, catalog number: 534625), which was studied from images available on the U.S. National Entomological Collection website (https://collections.nmnh.si.edu/search/ento/), the axillae are small with relatively straight lateral margins (as opposed to large with convex lateral margins) and the T1 discal patch is strongly rectangular (as opposed to umbrella-shaped). The whereabouts of the (male) holotype of T. hopkinsi is unknown; according to the original description ( Cockerell 1905), the specimen has been returned to Mr. (Henry Lorenz) Viereck, but the repository was not indicated. However, the species was described as having pale grayishcreamy markings, a strongly bilobed mesoscutellum, and a narrow pygidial plate. By contrast, in E. emiliae the pale hairs are off-white/pale yellow, the mesoscutellum is only weakly bigibbous, and (as in most species of Epeolus ) the pygidial plate is broadly rounded posteriorly. In the (male) holotype of T. isocomae (USNM, catalog number: 534639), which was studied from images available at https://collections.nmnh.si.edu/search/ento/, the mandibles are simple (as opposed to bidentate). According to Cockerell’s (1916) original description, the (male) holotype of T. pomonalis belongs to Pomona College, but the specimen could not be found there and appears to have been lost (see Rightmyer 2008). Nevertheless, it was described as having black (as opposed to reddish orange) tegulae and legs as well as pale tomentum all along the margins of the mesoscutum except anteriorly in the middle (as opposed to only along the lateral and posterior margins) and resembling Triepeolus lunatus (Say, 1824) (as T. concolor ) and Triepeolus remigatus (Fabricius, 1804) in the original description ( Cockerell 1916). Unfortunately, the original description of E. scelestus var. tubercularis is short and insufficiently detailed and the type repository is not indicated ( Brues 1903), but the (female) holotype was described as differing from “typical scelestus ” in terms of integument coloration, and Rightmyer (2008) indicated that the name is likely a junior synonym of Triepeolus scelestus (Cresson, 1878) . Since the type locality (Austin, TX, USA) for E. scelestus var. tubercularis is well outside the known range of E. emiliae , it seems highly improbable that both names correspond to the same species. Lastly, in the (male) holotype of T. sequior (American Museum of Natural History, New York, NY, USA, catalog number: AMNH_IZC 00323957), which was studied from images kindly supplied to the authors by Museum Specialist Corey Smith, the tegulae are dark brown/black (as opposed to reddish orange), the axillae are small (unlike in E. emiliae ), and the profemora and protibiae (except their apices) are dark brown/black (as opposed to entirely reddish orange).

As a result of the discovery of the new species E. emiliae , the total numbers of Epeolus species confirmed from Canada and the United States are now 14 and 44, respectively. With the modifications to the existing keys presented below, both sexes of E. emiliae can be readily identified among Canadian Epeolus as well as all North American members of the genus known from north of Mexico.

Modifications to the key to species of Epeolus in Canada of Onuferko (2017) to include E. emiliae new species

Note that the couplet below replaces couplet 6 of the original key and the latter is no longer needed.

6(4). Axilla with tip extending well beyond midlength of mesoscutellum; axilla large and robust (AL/MSCW ratio>0.4), its lateral margin arcuate (except sometimes in E. autumnalis ) ( Onuferko 2017: fig. 13a, b).................................................................................. 7

— Axilla with tip at most extending to midlength of mesoscutellum; axilla small (AL/MSCW ratio <0.4), its lateral margin relatively straight ( Onuferko 2017: fig. 13c, d)........................................................................... couplet 9 of the original key ( Onuferko 2017)

7(6). T 1 in dorsal view with lateral longitudinal band at least half as wide as breadth of apical fascia ( Fig. 1B, D , 3B ); T1–T3 with fasciae on or very little removed from apical margins of terga and complete, those of T2 and T3 more or less evenly broad ( Fig. 1B, D , 3B )................ E. emiliae new species

— T 1 in dorsal view with discal patch so wide that lateral longitudinal band barely visible (its width less than half maximum breadth of apical fascia) ( Fig. 3A ; Onuferko 2017: fig. 9d); T1–T3 with apical fasciae at least somewhat removed from apical margins of terga medially, commonly narrowed or narrowly interrupted medially ( Fig. 3A ; Onuferko 2017: fig. 9d, pl. 1C, L, M)............................................................... couplet 7 of the original key ( Onuferko 2017)

Figures

Figure 1. Epeolus emiliae new species. A–B. Allotype, ♀ (CSUC). A) Habitus, lateral view. B) Habitus, dorsal view. C) Paratype, ♂ (CNC 719832), habitus, lateral view.D) Holotype, ♂ (RSKM RSKM_ENT_E-191681), habitus, dorsal view.

Figure 2. Axillae and mesoscutellum of female, dorsal view. A) Epeolus autumnalis Robertson, 1902 (BOLD sample ID: sheffT-52, RSKM RSKM_ENT_E-0101152). B) E. emiliae new species, paratype (UCBME P 0219060). Blue lines indicate the posterior extent of the axilla relative to the length of the mesoscutellum; red lines indicate the extent of the free portion of the axilla relative to its entire medial length.

Figure 3. Metasoma of female, dorsal view. A) Epeolus autumnalis Robertson, 1902 (BOLD sample ID: 00-NS-0187, RSKM RSKM_ENT_E-0101148). B) E. emiliae new species, paratype (UCBME P 0219060) (blue arrow indicates anterolateral extension of T2 fascia).

Figure 4. Pseudopygidial area of female, dorsal view. A) Epeolus autumnalis Robertson, 1902 (DEBU debu00402177). B) E. emiliae new species, paratype (UCBME P 0219060). The pseudopygidial area is the apical portion of T5 that changes slope from the rest of the tergum and is covered in short, coppery or silvery hairs (posteromesad the light blue lines).

Figure 5. Approximate geographic ranges of Epeolus autumnalis Rob-

Figure 6. Female Epeolus emiliae new species visiting flowers of hairy golden aster (Heterotheca villosa (Pursh) Shinners (Asteraceae)) (location: Richland, Washington, USA). A) Shown with the specimen in dorsal view. B) Shown with the specimen in posterior view and the pseudopygidial area visible. Images courtesy of L. Hill.

Figure 7. A neighbor-joining tree that includes all COI sequences on BOLD assigned the BIN BOLD:AAF2361 as well as a sequence of a member of the nearest BIN (BOLD:AAF2273), generated in Geneious and based on the Tamura-Nei genetic distance model. The sequence for Epeolus emiliae new species is newly published whereas all others were downloaded from the BOLD Public Data Portal (www.boldsystems.org/index.php/Public_BINSearch?searchtype=records). Each sample is labeled with the following information in the following order: species name, BOLD sample ID, country and province or state of collection, sequence length (with the number of ambiguous bases indicated in square brackets), BIN uniform resource identifier, and GenBank accession number. Scale bar = 2% pairwise distance.

Figure 8. Dissected S7 (left) and S8 (right), ventral view, of male Epeolus

Figure 9. Dissected genitalia of male Epeolus emiliae new species (BOLD sample ID: CCDB-25139 G09, RSKM RSKM_ENT_E-185215) (with posterior end oriented toward the top). A) Dorsal view. B) Ventral view.