Epeolus mesillae (Cockerell, 1895)

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 : 110-113

32. Epeolus mesillae (Cockerell, 1895) Figs 67, 68, 91D

Phileremus mesillae Cockerell, 1895. Psyche (suppl.) 7: 10 (♂), new neotype designation.

Epeolus mesillae Cockerell, 1934. Am. Mus. Novit. 697: 12.

Epeolus mesillae palmarum Linsley, 1939. Pan-Pac. Entomol. 15: 2 (♀), syn. n.

Diagnosis.

The following morphological features in combination can be used to tell E. mesillae apart from all other North American Epeolus : the axilla does not attain the midlength of the mesoscutellum and like the mesoscutellum is black, the fore wing has two submarginal cells, and T1-T4 have complete fasciae. Only in E. americanus and E. asperatus is the fore wing commonly with two submarginal cells, but in both species at least the T1 and T2 apical fasciae are interrupted or at least greatly narrowed medially. Epeolus brumleyi is similar to E. mesillae in axillar structure; in that in females F2 is shorter, as long as wide; and in that T1-T4 have complete fasciae. However, in E. brumleyi the axilla is commonly ferruginous in part and the fore wing has three submarginal cells.

Redescription.

MALE: Length 6.6 mm; head length 1.7 mm; head width 2.4 mm; fore wing length 4.9 mm.

Integument coloration. Mostly black; notable exceptions as follows: at least partially ferruginous on mandible, antenna, pronotal lobe, tegula, and legs. Mandible orange between dark brown base and reddish-brown apex; preapical tooth slightly lighter than mandibular apex (difficult to see in the P. mesillae neotype because mandible closed; described from non-type specimens). Flagellum brown, except F1 extensively orange, and slightly lighter than dark brown scape and pedicel. Pronotal lobe reddish brown. Tegula pale ferruginous to amber. Wing membrane hyaline throughout. Legs, except tarsi, with brown or black more extensive than reddish orange.

Pubescence. Face with tomentum densest on clypeus and around antennal socket, sparser on upper paraocular area and vertexal area. Dorsum of mesosoma and metasoma with bands of off-white to pale yellow short appressed setae. Mesoscutum with paramedian band partly obscured by surrounding pale tomentum. Mesopleuron almost entirely obscured by white tomentum, except where rubbed off in the P. mesillae neotype. Metanotum with tomentum uninterrupted, uniformly off white. T1 with discal patch elliptical, narrow, and short. T2-T6 each with complete fascia, those of T2 and T3 somewhat broader laterally, T2 with fascia with anterolateral extensions of sparser tomentum. S3-S5 with long coppery to silvery subapical hairs.

Surface sculpture. Punctures dense. Labrum and clypeus with punctures equally dense (i<1d). Small impunctate spot lateral to 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) to rugose; mesopleuron with punctures more or less equally dense throughout. Metasomal terga with punctures very fine, dense (i≈1d), evenly distributed on disc.

Structure. Labrum with pair of small subapical denticles, each preceded by small discrete longitudinal ridge. Frontal keel not strongly raised. Scape with greatest length 1.7 × greatest width. F2 nearly as long as wide (L/W ratio = 0.9). Preoccipital ridge not joining hypostomal carina, from which it is separated by about 1.5-2 MOD at its terminal (difficult to see in the P. mesillae neotype; described from non-type specimens). Mesoscutellum moderately bigibbous. Axilla small to intermediate in size, its lateral margin (L) less than half as long as mesoscutellar width (W) (L/W ratio = 0.3) and tip not extending beyond midlength of mesoscutellum; axilla with tip visible, but unattached to mesoscutellum for less than 1/3 the medial length of axilla; axilla with lateral margin relatively straight and without carina. Fore wing with two submarginal cells. Pygidial plate apically rounded, with large deep punctures closely clustered.

FEMALE: Description as for male except for usual secondary sexual characters and as follows: F2 slightly longer, as long as wide (L/W ratio = 1.0); wing membrane sub hyaline, apically dusky; T5 with large, continuous patch of pale tomentum bordering and separate from pseudopygidial area present only in female; T5 with pseudopygidial area lunate, its apex more than twice as wide as medial length, indicated by silvery setae on impressed disc of apicomedial region elevated from rest of tergum; S3-S5 with much shorter hairs (S5 with apical fimbria of coppery to silvery hairs extending beyond apex of sternum by ~2/5 MOD); pygidial plate apically truncate, with small, denser punctures.

Distribution.

Known to occur in all major North American deserts (Fig. 68).

Ecology.

HOST RECORDS: Colletes clypeonitens Swenk is the presumed host of E. mesillae ( Hurd and Linsley 1975). Personal observations support such an association. In Whitewater, California, USA, I have collected large numbers of female E. mesillae and male C. clypeonitens in an area dominated by creosote bush ( Larrea tridentata ( Sessé & Moc. ex DC.) Coville ( Zygophyllaceae )) in late March 2016. Only one specimen (a female) of a different species of Colletes ( C. larreae Timberlake) was taken at the same locality.

FLORAL RECORDS: Collection records from data contributors to Discover Life ( Ascher and Pickering 2017) compiled by J. Pickering indicate the following floral associations: Cryptantha flavoculata (A. Nelson) Payson, Erigeron canus A. Gray, Heterotheca villosa , Larrea tridentata , and Potentilla hippiana Lehm. ( Rosaceae ). Labels of examined voucher specimens further indicate associations with Baileya pleniradiata Harv. & A. Gray ex A. Gray ( Compositae ), Chaenactis stevioides Hook. & Arn. ( Compositae ), Dimorphocarpa wislizeni (Engelm.) Rollins ( Brassicaceae ), L. glutinosa Engelm., Melilotus Mill., Psoralea lanceolata Pursh ( Leguminosae ), Prosopis velutina Wooton ( Leguminosae ), and Tamarix gallica L. ( Tamaricaceae ).

Discussion.

Epeolus mesillae was originally described under the now defunct genus Phileremus because the fore wing in this species has two rather than three submarginal cells, the typical state for most Epeolus species. Among North American Epeolus , E. mesillae exhibits unusual sexual dimorphism in that in females the fore wing and (to a lesser extent) hind wing are apically dusky whereas in males the wings are hyaline throughout. There is some variability in the pubescence on the metasomal terga among specimens, with some exhibiting more grayish-white than yellowish fasciae. Linsley (1939) recognized specimens from southern California as a distinct subspecies ( E. mesillae palmarum) based on a larger body size and the presence of pale tomentum interspersed with darker tomentum on the discs of the metasomal terga, especially laterally. Specimens from across the range of this species exhibiting these features have been examined, as well as specimens from southern California in which the metasomal fasciae are clearly distinct from the all-dark discs. Specimens from near the type locality of E. mesillae palmarum were barcoded, and their sequences cluster closely with those from specimens from Southeast Arizona and adjacent Sonora, nearer the type locality (Las Cruces, New Mexico) of E. mesillae mesillae. Hence, I do not consider these to be distinct subspecies, and herein synonymize E. mesillae palmarum under E. mesillae , a change in taxonomic status first proposed by Brumley (1965).

I have not seen the male holotype of P. mesillae and do not know where it is housed, despite personally searching through the entomological collections where T.D. Cockerell deposited the types of other Epeolus species he described. In Brumley (1965), no reference was made to Cockerell’s holotype of P. mesillae , suggesting Brumley too was unable to find it. Moreover, no references in the literature to Cockerell’s type since the species’ original description could be found. In the same publication, another species was described under Phileremus - P. verbesinae (now Neolarra verbesinae (Cockerell)) -, which was redescribed by Michener (1939) who indicated that the type was in the T.D.A. Cockerell Collection. It is unclear if either specimen has since ended up in an institution that maintains a research collection, but that the holotype of E. mesillae has not been referenced since its original description strongly suggests it is unlikely to turn up in the future and to all intents and purposes has been lost. In my search for the holotype at the CUM, a male specimen of E. mesillae (labelled as Phileremus mesillae Ckll.) from Mesilla Park (the original type locality) collected by Cockerell from Dimorphocarpa wislizeni on May 7th was discovered. The specimen, which is the property of the CUM, agrees with the original description, and was used to write the present redescription and diagnosis. Given that a synonymy under E. mesillae is proposed herein, it is sensible to have a neotype to serve as a point of reference for any future comparisons. Aside from the collection date, the specimen selected as the neotype of Phileremus mesillae fits the description of the original, which can no longer be traced. Hence, in this particular case the qualifying conditions for designating a neotype as listed under Article 75.3 of the International Commission on Zoological Nomenclature (ICZN) Code (http://iczn.org/iczn/index.jsp) seem to have been met.

Material studied.

Type material. Primary: USA: California: Edom (Riverside County), 28.iii.1936, E.G. Linsley ( E. mesillae palmarum holotype ♀ [CAS, catalog number: 04789]); New Mexico: Mesilla Park, 07.v.????, T.D. Cockerell ( P. mesillae neotype ♂, CUM).

Secondary: USA: California: 1 mi W Edom (Riverside County), 28.iii.1936, E.G. Linsley ( E. mesillae palmarum allotype ♂ [CAS, catalog number: 04790]).

DNA barcoded material with BIN-compliant sequences.

Available. BOLD:AAF0161. Specimens examined and sequenced.-Mexico: Sonora: 30 km E Agua Prieta (31.3333°N; 109.2403°W), 25.iv.2006, R.L. Minckley (3♀, 1♂, PCYU), 03.v.2005, R.L. Minckley (2♂, PCYU).

USA: Arizona: Douglas R/C Flying Field (31.3430°N; 109.4980°W) (Cochise County), 28.iv.2016, T.M. Onuferko (1♀, PCYU); California: 31 km N Lucerne Valley (34.6840°N; 116.9605°W) (San Bernardino County), 27.iv.2013, Z.M. Portman (1♂, BBSL); Kelso Dunes (34.8940°N; 115.7020°W) (Baker, San Bernardino County), 30.iv.2013, A. Ruttan (1♂, PCYU); Tipton Road (33.9079°N; 116.6510°W) (~1.4 mi SW Whitewater, Riverside County), 26.iii.2016, T.M. Onuferko (1♀, PCYU).

Non-barcoded material examined.

Mexico: Baja California: Near La Zapopita Valle de Trinidad, 09-14.iv.1961, F.S. Truxal (2♂, LACM); Baja California Sur: 19 mi SW S. Miguel Comondu, 23.vi.1967, E.L. Sleeper and E.M. Fisher (1♂, LACM); Sonora: 30 km E Agua Prieta (31.3333°N; 109.2403°W), 03.v.2005, R.L. Minckley (1♀, 5♂, PCYU).

USA: Arizona: 11 mi NW Wickenberg, 18.iv.1993, J.G. Rozen (2♀, AMNH); 2 Km W Pima (32.9833°N; 110.2833°W) (Graham County), 25.iv.1996, R.L. Minckley (2♂, PCYU); 2 mi S Willcox (Cochise County), 07.v.1956, E. Ordway (1♀, AMNH); 2.5 mi S Willcox (Cochise County), 24.v.1956, E. Ordway (1♂, AMNH), 07.vi.1956, E. Ordway (1♂, AMNH); 4 mi E Willcox (Cochise County), 08.v.1986, J.G. Rozen (3♀, AMNH), 15.v.1986, J.G. Rozen (1♀, AMNH), 16.v.1986, J.G. Rozen (1♀, AMNH), 17.v.1986, J.G. Rozen (2♀, AMNH); 5 mi NE Douglas (Cochise County), 13.v.1987, J.G. Rozen (1♀, AMNH); Douglas R/C Flying Field (31.3430°N; 109.4980°W) (Cochise County), 23.iv.2016, T.M. Onuferko (2♀, PCYU), 28.iv.2016, T.M. Onuferko (1♀, PCYU); Beaver Dam (36.9028°N; 113.9145°W) (1.7 mi ENE Beaver Dam Wash, Mohave County), 10.v.2014, M.C. Orr (1♀, 1♂, BBSL); Skeleton Canyon Road (Cochise County), 12.v.1977, J.G. Rozen (1♂, AMNH); Southwestern Research Station (5 mi W Portal), 23.iv.1956, E. Ordway (1♀, AMNH); Willcox (Cochise County), 16.v.1985, J.G. Rozen (1♂, AMNH); California: 1 mi W Searchlight Junction (San Bernardino County), 21.iii.1971, R.F. Denno and R.W. Rust (1♂, UCBME); 18 mi W Blythe (Riverside County), 22.iv.1978, R.M. Bohart (1♂, UCBME); 25 mi E Twentynine Palms (34.0806°N; 115.5667°W) (Riverside County), 16.iv.2005, L. Packer (1♂, PCYU); 31 km N Lucerne Valley (34.6840°N; 116.9605°W) (San Bernardino County), 27.iv.2013, Z.M. Portman (1♂, BBSL); Borrego Springs (San Diego County), 31.iii.1973, C. Goodpasture (3♂, UCBME); Borrego Valley (San Diego County), 02.iv.1973, R.M. Bohart (1♂, UCBME); Darwin Falls (Inyo County), 12.v.1974, R.M. Bohart (1♀, UCBME); Goffs (San Bernardino County), 24.iv.1993, J.G. and B.L. Rozen (3♀, AMNH), 06.v.1993, J.G. and B.L. Rozen (1♀, AMNH); Morongo Valley (San Bernardino County), 27.iv.1962, O.C. La France (2♂, AMNH); Thousand Palms (Riverside County), 02.iv.1966, R.O. Schuster (1♂, UCBME); Tipton Road (33.9079°N; 116.6510°W) (~1.4 mi SW Whitewater, Riverside County), 26.iii.2016, T.M. Onuferko (6♀, PCYU); Colorado: Foster Ranch (El Paso County), 21.vi.1978, F.M. Brown (1♂, CUM); Nevada: 1 mi N Crystal (Nye County), 25.v.1999, L. Packer (1♀, PCYU); 2.8 mi E Wadsworth (Washoe County), 30.vi.1963, G.I. Stage (1♀, AMNH); E Las Vegas (36.0983°N; 115.0025°W) (Clark County), 29.iv.2001, A.L. Hicks and V. Scott (1♀, CUM); Overton (Clark County), 09.v.1958, R.C. Bechtel (1♀, AMNH); Sams Camp Wash (Lincoln County), 10.v.-11.vi.1984, R.C. Bechtel and J.B. Knight (1♀, BBSL); New Mexico: 10 mi S Animas (Hidalgo County), 15.v.2013, J.G. Rozen (1♂, AMNH); 15 mi E Animas (Hidalgo County), 15.v.2013, J.G. Rozen (3♂, AMNH); Carlsbad (Eddy County), 20.v.1969, Brothers, Krueger, and Michener (1♂, KUNHM); Road Forks (Hidalgo County), 16.v.2013, J.G. Rozen (2♂, AMNH); Texas: 20 km S Kent (Jeff Davis County), 30.iv.2003, L. Packer and G. Fraser (1♀, PCYU); 7.6 mi S Van Horn (Culberson County), 27.iv.1979, R.R. Snelling (1♂, LACM); Chihuahuan Desert Research Institute (Jeff Davis County), 29.iv.2003, L. Packer and G. Fraser (2♀, PCYU); Utah: Dry Fork (Kane County), 22.v.2000, O. Messinger (1♀, BBSL).