Osmia (Acanthosmioides) palmula, Rightmyer, Molly G. & Griswold, Terry, 2010

Rightmyer, Molly G. & Griswold, Terry, 2010, Description of a new species of Osmia (Hymenoptera: Megachilidae) from southwestern North America, with a redescription of the enigmatic species Osmia foxi Cameron, Zootaxa 2512, pp. 26-46 : 33-39

Osmia (Acanthosmioides) palmula new species

( Figs. 20–40 , 42 )

Diagnosis. —Females of O. palmula can be distinguished as belonging to Acanthosmioides by their mandibles, which are apically widened (two times wider than the median width), and by the relatively widely spaced lower teeth (apical tips of these teeth 1.3 times wider than apical tips of middle, i. e., second, and dorsal teeth) ( Fig. 23 ). Within Acanthosmioides, females of O. palmula are most similar to O. unca Michener , but can be distinguished from that species by the relatively strong third tooth of the mandible (forming distinctly pointed tooth on margin nearest second tooth) ( Fig. 23 ) and by the white hairs of the mesepisternum ( O. unca has dark hairs on the mesepisternum in the portion of its range that overlaps O. palmula , and paler hairs in more northern locations). Osmia palmula is known from other female Acanthosmioides by the following combination of characters: 1. Vertex, mesoscutum, scutellum, and T1 with white hairs (black hairs sometimes interspersed on vertex and mesoscutum); 2. Vertex lacking distinct depression posterior to lateral ocelli (or if with slight depression then this depression only immediately posterior to ocelli); 3. Gena in lateral view with ventral and dorsal margins rounded away from each other (hypostomal area convex); 4. Propodeal triangle with lower, lateral or entire half to third glabrous, strongly shining ( Fig. 24 ); 5. Metasomal terga with wide impunctate bands at the apical margins ( Fig. 25 ).

Males are readily distinguished by the enlarged, flattened F11, the apical tip of which is black (strongly contrasting with remainder of antenna, which is orange) and shining on the posterior surface (when antenna is directed upwards) ( Figs. 27–29 ). The only other Osmia species with the combination of this type of antenna and no process on S2 is O. watsoni Cockerell ; O. palmula can be distinguished from O. watsoni by the following two characters: 1. S4 midapically has a dense patch of coarse, orange-brown hairs plus an additional fringe of medially uninterrupted stout orange-brown hairs along the apical margin ( Fig. 34 ) (in O. watsoni , the midapical patch of hairs on S4 is dark brown, and S4 lacks a medially uninterrupted fringe of hairs along the apical margin), 2. The gonoforceps has a distal process that is nearly three times as long as apical width ( Figs. 35, 38, 39 ) (only two times as long as apical width in O. watsoni ).

Description.—Female. Total length: 8.5–10.5 mm; forewing length: 6.4–7.2 mm; ocelloccipital distance: 0.5–0.7 mm; ocelorbital distance: 0.5–0.6 mm.

Color: Body gunmetal blue-green except brown to dark brown on mouthparts, labrum, most of mandible, most of clypeus, antenna ( Figs. 20, 21 ), posterior two-thirds of tegula, legs excluding hind coxa, and most of metasomal terga; brown to metallic blue-green on basal most part of mandible, basal margins of clypeus, hindcoxa, apical margins of metasomal terga, and entire metasomal sterna. Forewing very weakly infuscate, slightly more strongly infuscate distal to cells and near C and R1 veins.

Pubescence: Clypeus below apical margin with lateral tuft of golden, medially directed hairs. White, minutely branched hairs on paraocular area, frons, mesepisternum, metepisternum, propodeum, posterior surfaces of femora, and inner surface of hind tibia; brown to black, stouter hairs on labrum, clypeus, inner surfaces of legs distal to femora excluding hind tibia (sometimes golden on tarsi), and scopa (sometimes with pale hairs laterally on scopa); golden to white, minutely branched hairs on remainder of body, usually with longer black hairs intermixed on mandible, vertex, and hypostomal area; forewing membrane covered with brown, short, simple hairs. Galea with hairs on lateral margin straight, 0.2–0.3 OD in length. Labrum with long hairs arranged in two curved, transverse rows, along subapical margin and approximately at midpoint, with additional fringe of minute hairs at apical margin. Clypeus with hairs dense. Hypostomal area with hairs evenly distributed across area, straight to very weakly curved medially, 2.0–3.0 OD in length. Mesepisternum with hairs ca. 2.0–3.0 OD in length. T1 with hairs relatively dense and long, about 1.5 OD laterally ( Fig. 20 ).

Punctation: Head and mesosoma with punctures nearly contiguous, more or less round, and deeply impressed except as follows: labrum mostly impunctate; clypeus with impunctate midapical truncation about length of F4, basolaterally sparser to mostly impunctate (near anterior tentorial pit and along epistomal sulcus ventral to anterior tentorial pit); small area medially on vertex with punctures separated by up to a 0.5 to 1.0 puncture diameter; hypostomal area with punctures spaced up to one puncture diameter; mesoscutum immediately posterior to median longitudinal sulcus with punctures separated by up to one puncture diameter; tegula with punctures minute, sparse medially and posteriorly, separated by up to ten or more puncture diameters; mesepisternum with small patch medially on upper third and medially on lower half with punctures separated by half a puncture diameter; metepisternum along anterior margin nearly impunctate; pronotum, ventral metepisternum, legs, and lateral and posterior surfaces of propodeum with punctures weakly, shallowly impressed; propodeal triangle with dorsal half areolate on dorsal fourth, shagreened on ventral fourth, lower half of triangle glabrous and shining at least laterally ( Fig. 24 ). T1 with anterior surface shining, with minute, sparse punctures dorsally; T1–T3 dorsal surfaces excluding apical margins with punctures distinct and well-impressed, generally separated by about a puncture diameter (sometimes nearly contiguous, rarely separated by up to three puncture diameters); apical impunctate margins polished to weakly shagreened (T1 length at midpoint up to 5.0–6.0 puncture diameters, submedially as narrow as 2.0 puncture diameters; T2 length 3.0–4.0 puncture diameters, Fig. 25 ; T3 length 5.0–6.0 puncture diameters). T4–T6 with punctures less distinctly impressed and background integument weakly shagreened to shining (becoming more strongly so on each successive posterior tergum), with punctures nearly contiguous to separated by 2.0 puncture diameters; T4–T5 with apical impunctate margins 4.0–6.0 puncture diameters in length. Vertex, mesoscutum medially, mesepisternum, and T1–T3 medially with sparse, minute punctures interspersed between larger punctures.

Structure: Labial palpus four-segmented, second labial palpal segment subequal to basal most segment. Maxillary palpus five-segmented. Mandible with outer and condylar ridges parallel along length, of subequal thickness, outer ridge often higher than condylar ( Fig. 22 ); apical margin with four teeth, third separated from second and fourth by weak carina, sometimes only differentiated from fourth tooth by difference in plane (appearing as inward folding of fourth tooth), margin of third tooth forming deep V-shape with adjacent margin of second, margin of third tooth forming weak U-shape with adjacent margin of fourth ( Fig. 23 ); inner, ventral margin of mandible lacking distinct tooth, diverging away from condylar ridge basally; mandible apically widened (two times wider than median width), first tooth much longer than other teeth, apical tips of first and second teeth 1.3 times wider than apical tips of second and fourth teeth ( Fig. 23 ). Clypeus with apical truncation distinguished from remainder of apical margin laterally by slight folding of integument. F1 twice length of F2 or slightly more, remaining flagellar segments gradually increasing in length such that F9 nearly as long as F1, F10 1.2 times length of F1. Vertex behind lateral ocellus 2.2–2.5 OD in length. Genal width subequal to that of compound eye in lateral view. Preoccipital margin rounded, not carinate. Hypostomal carina moderately high, highest a third to half way between anterior angle and posterior area where hypostomal carina curves towards occiput, gradually tapering to near obsolescence at angle, not forming distinct tooth. Malus forming distinct apical spine. Fore- and midtarsal segments excluding basitarsal and apical-most segments with anterior lobes slightly longer than posterior. Hind tarsal segments with anterior and posterior lobes of equal width, not swollen. Hind tibial spurs curved at apical tips, outer spur about a fifth shorter than inner. Hind basitarsal segment with lateral margins of outer surface subparallel.

Male. Total length: 11.8 mm (9.5–12.4 mm); forewing length: 6.5 mm (5.8–6.6 mm); ocelloccipital distance: 0.6 mm (0.5–0.7 mm); ocelorbital distance: 0.5 mm (0.4–0.5 mm).

Color: Body gunmetal blue-green except sometimes brassy on face and anteriorly on mesosoma; bright orange on flagellar segments excluding most of F11 ( Figs. 26, 27 ); brown to dark brown on mouthparts, labrum, most of mandible, apical margin of clypeus, scape, pedicel, most of F11, posterior two-thirds of tegula, legs excluding forecoxa, hind coxa and hind femur, and apical margins of metasomal terga; brown to metallic blue-green on basal most part of mandible, forecoxa, hind coxa, hind femur, and metasomal sterna. Forewing clear to very weakly infuscate, sometimes slightly more strongly infuscate distal to cells and near C and R1 veins.

Pubescence: White, minutely branched hairs covering body except as follows: golden on inner surfaces of legs distal to femora excluding hind tibia, S5, and midapically on S4 and S6; forewing membrane covered with brown, short, simple hairs. Galea with hairs on lateral margin straight, 0.4–0.5 OD in length. Labrum with long hairs arranged in two curved, transverse rows, along subapical margin and approximately at midpoint, with additional fringe of minute hairs at apical margin. Clypeus with hairs extremely dense ( Fig. 27 ). Hypostomal area with straight hairs evenly, densely distributed across area, 1.5–3.0 OD in length. Mesepisternum with hairs ca. 2.0–3.0 OD in length. T1 with hairs relatively dense and long, about 2.0 OD laterally. T2–T5 with dense bands of hairs forming subapical fringes immediately basal to impunctate apical margins. S2–S3 sublaterally with hairs relatively long (2.0–3.0 OD), S2 midapically with small tuft of shorter hairs, S3 with hairs mostly filling midapical emargination, entirely posteriorly directed, ca. 1.0 OD in length ( Fig. 33 ). S4 apical margin with fringe of stout, posteriorly directed, golden hairs; subapically with patch of finer, more ventrally directed, apically curved hairs, this patch weakly medially interrupted by longitudinal impunctate stripe ( Fig. 34 ). S6 with apical third of midapical truncation covered with short, papillate hairs ( Fig. 36 ).

Punctation: Head and mesosoma with punctures nearly contiguous, more or less round, and deeply impressed except as follows: labrum mostly impunctate on upper and lower thirds; clypeus with apical margin impunctate, about 0.5 length of F1; mesoscutum immediately posterior to median longitudinal sulcus with punctures separated by up to one puncture diameter; tegula with punctures minute, sparse medially and posteriorly, separated by up to seven puncture diameters; metepisternum along anterior margin nearly impunctate, on ventral half with punctures separated by up to one puncture diameter; gena posteriorly and ventrally, hypostomal area, pronotum, mesepisternum ventrally, metepisternum dorsally, legs, and lateral and posterior surfaces of propodeum with punctures weakly, shallowly impressed; propodeal triangle finely areolate on dorsal fourth to third, shagreened medially, lower fourth to third of triangle glabrous, shining, especially laterally ( Fig. 30 ). F11 posterior surface polished on apical half ( Fig. 29 ). T1 with anterior surface shining, with sparsely scattered, minute punctures; T1–T4 dorsal surfaces (excluding apical margins) shining, with punctures distinct and well-impressed, nearly contiguous to separated by about a puncture diameter; apical impunctate margins polished to weakly shagreened (T1 length at midpoint 4.0–5.0 puncture diameters, submedially only 1.0–2.0 puncture diameters; T2 length about 4.0 puncture diameters; T3 length about 6.0 puncture diameters; T4 length 7.0–9.0 puncture diameters). T5–T7 with punctures slightly less distinctly impressed (especially on T6–T7), with punctures nearly contiguous to separated by about a puncture diameter, T5 with apical impunctate margin shagreened, about 10.0 puncture diameters in length, T6–T7 with apical impunctate margins shining, T6 length about 3.0–5.0 puncture diameters, T7 length about 2.0 puncture diameters. S1, S3–S5 with punctures weakly, shallowly impressed, S4 subapically with punctures minute, apical margin lateral to emargination impunctate, translucent. S2 with punctures minute, distinctly impressed, nearly contiguous laterally to medially separated by 4.0–5.0 puncture diameters. S6 shining, mostly impunctate. Mesoscutum medially and T1–T4 medially with sparse, minute punctures interspersed between larger punctures.

Structure: Mandible with outer and condylar ridges parallel to very weakly converging apically; apical margin with two teeth, upper tooth much shorter and wider than lower, upper tooth with inner and dorsal margins forming right angle; inner ventral margin of mandible diverging away from outer ridge basally. Clypeus with apical margin straight medially, weakly concave sublaterally, forming weak apical truncation. Flagellar segments subequal in length, weakly crenulate, with F11 slightly longer than other segments; F11 distinctly widened, flattened apically and shining on posterior surface ( Figs. 28, 29 ). Vertex behind lateral ocellus about 2.0 OD in length or little more. Genal width three-fourths (to one-third ventrally) that of compound eye in lateral view. Preoccipital margin rounded, not carinate. Hypostomal carina moderately high, gradually tapering to near obsolescence at angle, not forming distinct tooth. Malus forming distinct apical spine. Fore- and midtarsal segments excluding basitarsal and apical-most segments with lobes very weakly, equally swollen (less so in midtarsal segments). Hind tibial spurs weakly curved at apical tips, outer spur about a fifth shorter than inner. Hind tarsal segments (excluding hind basitarsal) not swollen. Hind basitarsal segment with tooth on inner margin very strongly developed, about a quarter of hind basitarsal segment length in size, arising at midpoint of segment; hind basitarsal segment with lateral margins of outer surface diverging apically. T6 midapically lacking emargination, weakly emarginate, or if distinctly emarginate then forming very small semicircle in outline ( Fig. 31 ); subapically at middle of T6 with integument transversely convex, appearing almost swollen; T6 lateroapically with irregular emargination, forming very slight process laterally on apical margin ( Fig. 31 ). T7 midapically narrowed, forming narrow process, this process strongly emarginate, forming semicircle that is as wide as deep (about 0.5 OD deep), with rounded teeth on either side about as wide as emargination width ( Fig. 32 ). S2 strongly convex, covering most of S3; slightly tapered medially, sometimes with weak midapical emargination; subapically weakly swollen. S3 with midapical emargination about one-fourth to one-third width of entire S3, about twice as wide as deep (1.5 OD in length) ( Fig. 33 ). S4 apical margin distinctly emarginate on middle half, lateral side of emargination sharply angled ( Fig. 34 ). S5 with apical margin emarginate on middle third. S6 with midapical truncation about one-fourth width of sternum apically, lateral sides of truncation more or less evenly joining lateral sides of S6, apical margin of truncation straight to weakly emarginate ( Fig. 36 ). S8 as in Fig. 37 . Gonoforceps with strong subapical swelling, with apical process arising from outer lateral margin of swelling and apical tip of process swollen, slightly flattened and spatulate ( Figs. 35, 38–40 ).

Distribution.—Southeastern Arizona and southwestern New Mexico, USA, and adjacent Sonora, Mexico. ( Fig. 42 ).

Holotype male.—“ USA Ariz.[Arizona], Santa Cruz Co., Sycamore Cyn.[Canyon] 3-IV-86 [3 April 1986] T. Griswold//on Astragalus // HOLOTYPE 3 Osmia palmula Rightmyer & Griswold BBSL 769750” ( LOGAN).

Paratypes.— MEXICO: SONORA: Agua Prieta, 30 km E, 31˚11’00”N 109˚00’10”W, 8 April 2006, R. Minckley et al. (1Ƥ, ROCHESTER); Agua Prieta, 60 km E, 31˚16’57”N 108˚47’39”W, 8 April 2006, R. Minckley et al. (1Ƥ, 13, ROCHESTER); USA: ARIZONA: Cochise Co., Peloncillo Mountains, Skeleton Canyon, 31˚ 35.38N 109˚ 01.68W, 1485 m., 1 May 2004, F. D. Parker, M. E. Irwin (1Ƥ, LOGAN); Santa Cruz Co., Patagonia, 6 mi S, 14 April 1965, Phacelia (13, LOGAN); Peña Blanca, Route 289, 10 April 1988, Lotus greenei (13, LOGAN); Sycamore Canyon, 3 April 1986, R. Griswold (5Ƥ, 233, LOGAN-TLG), Astragalus, T. Griswold (1Ƥ, 433, LOGAN), Lotus tomentellus, T. Griswold (13, LOGAN); NEW MEXICO: Hidalgo Co., Peloncillo Mountains, Skeleton Canyon, 31˚39.52’W 109˚05.50’W, 1349 m., 1–8 May 2004, F. D. Parker, M. E. Irwin (1Ƥ, LOGAN).

Etymology. —The name palmula is Latin meaning “oar, or blade of an oar” and is in reference to the enlarged and flattened F11 of the males. It is a feminine diminutive of palma.

Figures

FIGURE 42. Distribution of O. palmula, new species, with triangles representing individual collection localities. Hatched areas represent ecoregions to which the collection localities belong: Orange hatched area is the Sierra Madre pine-oak forest ecoregion; blue is the Chihuahuan Desert ecoregion.

FIGURES 20 – 25. Osmia (Acanthosmioides) palmula, new species, female. 20. Dorsal habitus. 21. Face. 22 – 23. Mandible. 22. Outer surface. 23. Apical margin. 24. Propodeal triangle. 25. Apical margin of T 2 and basal area of T 3.

FIGURES 26 – 33. Osmia (Acanthosmioides) palmula, new species, male. 26. Dorsal habitus. 27. Face. 28 – 29. Antenna, apical flagellar segments. 28. Outer surface. 29. Inner surface. 30. Propodeal triangle. 31. T 6. 32. T 7. 33. S 3 and S 4.

FIGURES 34 – 40. Osmia (Acanthosmioides) palmula, new species, male. 34. S 4. 35. Genital capsule, ventral view. 36. S 6. 37. S 8. 38 – 40. Genital capsule. 38. Dorsal view. 39. Ventral view. 40. Lateral view.