Nomada fragariae Mitchell

Droege, Sam, Rightmyer, Molly G., Sheffield, Cory S. & Brady, Seán G., 2010, New synonymies in the bee genus Nomada from North America (Hymenoptera: Apidae), Zootaxa 2661, pp. 1-32 : 11-13

Nomada fragariae Mitchell

Figures 7, 8 , 17, 18 , 22, 24–26

Nomada fragariae Mitchell 1962: 391 [ U.S. National Museum of Natural History, ♂; label data: “[ USA] Faison N. C. [North Carolina] Apr. [April] 20 1955// T. B. Mitchell, on strawberry// HOLOTYPE Nomada fragariae Mitchell [red label]// Type No. 75219 U.S. N.M. [red label]// USNM ENT 0 0 533926 [yellow barcode label]”].

Diagnosis. Females of N. fragariae are unique among similar species of Nomada in having absolutely no hair on the posterior surface of the propodeum (the other species having copious, long hair) particularly in combination with the uninterrupted bands of yellow maculations on their metasomal terga (Fig. 22). We are aware of only two other eastern species with restricted hair on the propodeum, namely N. graenicheri Cockerell and N. besseyi Swenk. (While not treated in this paper, these two species are likely to be synonymous). In N. fragariae , the hind tibia on the outer apical margin has four to six long, stout, spine-like hairs, of approximately the same length as the surrounding white hairs, and the stout, spine-like hairs are curved ventrally, not posteriorly as in N. luteoloides Robertson or N. imbricata Smith ( Fig. 17 ). In addition, the flagellar segments (on the posterior surface when the antenna is directed dorsally) have comparatively long, erect hairs in addition to the more commonly found microscopic, more appressed hairs found in this area when compared to similar species ( Fig. 24).

Males of N. fragariae are unique among similar looking species (e. g., N. luteoloides , N. imbricata , and N. annulata Smith ) in the shape, color, and especially pilosity of F11: when the antenna is directed dorsally, the anterior surface (of all flagellar segments including F11) is relatively pale, the apical tip of F11 is located near the midpoint of the flagellar segment or is only slightly shifted laterally (the apical tip is nearly at the lateral edge of F 11 in other species, although less extremely so in N. sulphurata ), and there are three to seven hairs that project out from the apical tip that, while microscopic, are distinctly visible when viewed through a microscope and are much longer than the small, appressed hairs that are scattered over the surface of F11 (there are no hairs projecting beyond apical tip of F 11 in the other species) ( Fig. 26). Additionally, the entire lateral margin of the mesoscutum usually has a narrow, sometimes faint, border of yellow ( Fig. 8 ). Only N. imbricata also has such a yellow lateral maculation on the mesoscutum. In most specimens of N. imbricata this border is absent; when present it is restricted to the margin posterior to the tegula (very rarely extending along the entire lateral margin), and the remaining similar species have no known instances of yellow on the mesoscutum. The scutellum of N. fragariae has a broad transverse band of yellow present in all examined specimens ( Fig. 8 ), unlike the common occurrence of two distinctly separated, round, yellow circles in similar species. The length of F1 is variable, but is usually about half the length of F2 ( Fig. 25). On the outer apical margin of the hind tibia there are four to eight stout, spine-like hairs that are usually difficult to detect as they blend into the white hairs surrounding them; nonetheless these stouter hairs are unique in that they are evenly spaced from each other, are found on the apical margin of the tibia, and are usually just slightly longer than the surrounding white hairs ( Fig. 18 ). The posterior surface of the propodeum is variable in the amount of yellow maculation present, ranging from absent (rare) to three separate pairs of patches (usually there is one maculation above the hind coxa, one laterally on the propodeal triangle, and often a fainter one in between these two maculations). The hypoepimeron usually has a very faint yellow maculation, and the mesepisternum centrally has a longitudinal yellow stripe extending from the anterior angle to the posterior margin. Finally, the anterior surface of the antenna (when directed dorsally) is yellow-brown.

Description of female. Total length: 9.5–10.5 mm; forewing length: 8.5–9.5 mm.

Color: Figures 7 , 22. Head predominantly yellow, with the following areas brownish-red: apical half of mandible, posterior surface of scape, anterior surface of pedicel and flagellar segments, and margins of clypeus and eye; the following areas black to brownish-red at margins: subantennal sulcus, posterior surface of pedicel and flagellar segments, area near antennal socket and ocelli, and preoccipital margin of gena. Mesosoma with the following areas yellow: pronotal collar dorsally, pronotal lobe, most of tegula, mesoscutum along lateral margin (thick band) and medially between center and lateral margin (thin longitudinal stripe), axilla, scutellum, submedially on metanotum, most of posterior surface of propodeum, most of lateral surface of mesepisternum including hypoepimeron, band between midcoxae on ventral surface of mesepisternum, forecoxa and part of hind coxa, apically on all femora, and most of outer surfaces of all tibiae; the following areas reddish-brown: most of mesoscutum, laterally on metanotum, small areas of tegula, anterodorsally, near scrobal groove, and ventrally on lateral surface of mesepisternum, most of ventral surface of mesepisternum, lateral surface of propodeum, most of legs; the following areas black: laterally on pronotum, anteromedially and anteroposteriorly on mesoscutum, medially on propodeal triangle, scrobal pit, anteroventrally on mesepisternum, metepisternum, and anterior margin of lateral surface of propodeum. Forewing weakly infuscate along most of length, more strongly infuscate at apical tip beyond closed cells. Metasoma with the following areas yellow: submedially on T1 (forming wide transverse stripe), most of discs but excluding apical margins on T2–T4, entire T5, small medial spot on S1, and most of discs but excluding apical margins on S2–S4; the following areas reddish-brown: apically on T1–T4, most of S1, apically on S2– S4, and entire S5–S6; with the following areas black: basally on T1 and basolaterally on S1.

Pubescence: Head sparsely covered with short, golden, suberect to appressed, unbranched hairs; in addition, the following areas sparsely covered with long, erect, reddish-golden, unbranched hairs: ventral margin of mandible (ca. 2–3 OD), labrum, clypeus, and anterior and lateral surfaces of scape and pedicel (ca. 1.5 OD), posterior surfaces of flagellar segments (ca. 0.5 OD), and vertex (ca. 1 OD); long, branched hairs on hypostomal area. Mesosoma excluding propodeum largely covered with sparse, short, suberect to appressed, unbranched to minutely-branched hairs; in addition, with long, erect to suberect, simple hairs interspersed on pronotal collar, mesoscutum, scutellum, and outer surfaces of legs; dense, golden, simple, subapressed hairs covering inner surfaces of tarsi. Midtibia with dense patch of golden hairs on anterior surface. Hind tibia on outer apical margin with four to six long, reddish, stout, ventrally-curved, spine-like hairs, about same length as surrounding white hairs ( Fig. 17 ). Propodeum mostly lacking hairs, with sparse, minute, appressed, translucent hairs visible under high magnification (Fig. 22). Entire forewing densely covered with short, brown hairs and lacking visible papillae. Metasoma entirely covered with sparse, short, suberect to appressed, unbranched hairs; in addition, with long, erect to suberect, simple hairs forming weakly defined, transverse row of hairs where basal yellow and apical reddish-brown integument meet on T3–T4 and S1–S4; long simple hairs more densely covering discs of T5 and S5. T5 laterally with very long, simple, white to golden hairs; medially with pseudopygidial area typical for most Nomada , subquadrate, wider than long, with dense, medially-parted, flattened, white to silvery-reflecting hairs. S5 sublaterally with dense tuft of long, unbranched, reddish, medially-curved hairs. As typical for Nomada , S6 with patch of stout, apically curved, red, spine-like hairs at apicolateral margin.

Punctation: Head with punctures minute and more or less evenly-spaced (ca. 1–2 puncture diameters apart on clypeus, interantennal area, frons, and gena; ca. 3–4 puncture diameters apart on paraocular area, especially near eye, and vertex). Hypostomal area with punctures wider and shallower, separated by 0.5 to 1.0 diameters. Mesosoma with punctures small, separated between 1.0 and 3.0 puncture diameters except as follows: nearly contiguous anteromedially on mesoscutum, on lateral and posterior surfaces of propodeum excluding propodeal triangle (punctures relatively shallow on propodeum), and ventral surface of mesepisternum; punctures minute and separated by at least three to five puncture diameters on pronotal lobe, tegula, and scutellum. Propodeal triangle with dorsal fourth very weakly reticulate, ventral three-fourths weakly shagreened (more strongly so near ventral margin). Metasomal terga excluding T5 with punctures extremely minute, separated between one and five or more puncture diameters, except apical margins of each tergum with impunctate transverse band about 0.5 OD in length (slightly shorter on T1). T5 subapically near pseudopygidial area with punctures larger, separated between one and two puncture diameters. Sterna basally (on areas with yellow integument) with punctures small, separated by one to three puncture diameters on medial third, grading to punctures minute and in places nearly contiguous on lateral two-thirds; apically (on areas with translucent reddish-brown integument) lacking punctures, with integument weakly shagreened.

Structure: Mandible long, simple, apically pointed. Malar space larger near acetabulum (condyle nearly touching ventral margin of eye). Labrum with apical margin subcarinate, weakly pointed midapically; disc of labrum with central denticle. Pedicel partly enclosed by scape. Flagellar segments excluding F10 subequal, each segment gradually decreasing in length moving apically; F10 longer than more basal segments, about a third longer than F9. Interantennal area with strong longitudinal carina extending posteriorly to midpoint of frons, gradually decreasing in height posteriorly. Preoccipital margin weakly carinate, especially on gena. Pronotal collar in dorsal view with apical margin not distinctly carinate, weakly concave, length at midpoint about 0.3 OD, length laterally about 1.0 OD. Malus with long apical spine distinctly separated from vellum by notch; apical spine with row of small teeth on ventral margin. Hind tibia with small but distinct triangular process on posterior corner of outer apical margin. Hind tibial spurs nearly straight, with outer spur about a fifth shorter than inner. Forewing with three submarginal cells.

Molecular results. We obtained DNA barcode data from one male specimen and one female specimen of N. fragariae collected in Calvert Co., Maryland ( Table 1). The sequence divergence between these specimens was only 0.3%. These nearly identical sequences provide further evidence that these are different genders of the same species. The description of the female provided herein is based on the specimen included in the molecular analysis.

Variation. In the males, the yellow maculation on T1 varies widely from uninterrupted to constricted to completely interrupted medially. Most individuals have uninterrupted transverse yellow maculations on the remaining metasomal terga; however, in a few individuals the maculation on T2 is constricted medially and, in a few, completely interrupted. All the examined males have a thin, lateral border of yellow on the otherwise black mesoscutum ( Fig. 8 ), although in a few specimens the yellow border does not extend to the anterior margin. The amount of yellow on the posterior surface of the propodeum varies from none to the diagnostic pattern mentioned in the Diagnosis section. Females did not demonstrate any significant variation in structure or color. We examined one male specimen from Talbot County, Maryland that appeared to be a specimen of N. fragariae except that the scutum was largely red and the yellow maculations were much greater in extent than in other known specimens of N. fragariae .

Distribution. Nomada fragariae is known from eastern seaboard states, from Georgia north to the coastal plain of Maryland.

Material examined. 63 specimens were examined from MD, NC, GA (Appendix).

Comments. This is the first description of the female of this species for which we are aware. Nomada fragariae is truly an uncommon species; given its unique morphology, surely the female would have been noticed by past taxonomists had they had specimens before them. Hosts have not been mentioned in the past and we have not gathered direct evidence either; however, most of the specimens from Calvert Co., Maryland, came from a month-long project run by taxonomists studying parasitic Hymenoptera at the U. S. Department of Agriculture who were investigating color preferences in bowl traps for various wasp groups. One of us (SD) looked at the approximately 8600 bee specimens collected in Calvert Co., and the only Andrena species whose phenology came close to matching that of N. fragariae were A. confederata Viereck and A. violae Robertson. Andrena confederata was the only common large species of Andrena present on the site (with 18 specimens recorded in total). Andrena violae is of moderate size and very common in Mid-Atlantic lawns and fields where violets are present. It would appear unlikely that A. violae was the host, as presumably many more specimens of N. fragariae would have been captured throughout its range if this were the case. Andrena confederata is uncommon throughout its range and has a largely southern distribution, which fairly well matches the distribution of the known specimens of N. fragariae . Andrena confederata is also known from the Midwest but it appears to be even less common there, and we are not aware of any N. fragariae specimens captured from that region.

Figures

FIGURES 7, 8. Nomada fragariae. Fig. 7. Dorsal habitus of female. Fig. 8. Head and mesosoma of male. FIGURES 9 – 12. Nomada lehighensis. Fig. 9. Dorsal habitus of female. Fig. 10. Dorsal habitus of male. Fig. 11. Female metasoma, lateral view. Fig. 12. Female T 5.

FIGURES 13 – 18. Outer apical surface of hind tibia. Figs. 13, 14. Nomada augustiana. Fig. 13. Female holotype. Fig. 14. Male. Figs. 15, 16. Nomada bethunei. Fig. 15 Female. Fig. 16. Male. Figs. 17, 18. Nomada fragariae. Fig. 17. Female. Fig. 18. Male.