Leiophron lygivorus (Loan)

Goulet, Henri & Mason, Peter G., 2006, Review of the Nearctic species of Leiophron and Peristenus (Hymenoptera Braconidae: Euphorinae) parasitizing Lygus (Hemiptera: Miridae: Mirini:), Zootaxa 1323 (1), pp. 1-118 : 24-26

Leiophron lygivorus (Loan)

( Figs. 1 habitus, 14, 28, 34, 35, 40, 50, 53, 55, 64, 65, 69, Table 2)

Euphoriana lygivora Loan, 1970: 193–194 . Type locality: Canada, Ontario, Fuller. Holotype, female (CNCI), labelled: [White] “Fuller, Ont., lat. 44º24'N long. 77º25'W C. C. Loan 14.VIII.1969 ”; [Red] “ HOLOTYPE Leiophron lygivora Loan CNC No. 11588 ”. Condition: left antenna, left wings, left mid leg above mesocoxa, and hind leg missing. Loan (1974a) added information not on the original label: “ 14.VIII.1969 is the emergence date, host Lygus lineolaris , nymphs collected on 21.VIII–6.IX.1968 on Solidago canadensis ”.

Leiophron trigonotylidis Loan, 1974a: 834 . Type locality: Canada Ontario, VI concession Sidney Township at highway 15. Holotype, female (CNCI), labelled: [White with black edge] Sidney VI at # 15 2­VI­70; [White with black edge] Ex Red clover; [Red] HOLOTYPE Leiophron trigonotylidis Loan CNC No. 13147. Condition: excellent, though protarsomeres 4 and 5 broken off and glued to right tarsus. In Loan’s description, the date was incorrectly recorded as “ 3.VI.1970 ”. NEW SYNONYMY.

Diagnosis. Vein RS+M absent, head and almost all of thorax very light reddish brown, posterior half of discal area of mesoscutum with deeply outlined and irregular transverse microsculpture, most males with 15 flagellomeres.

Description. FEMALE. Colour. Body generally very light reddish brown ( Fig. 1 ); small black spot anterior to ocelli ( Fig. 14 ); propodeum, metanotum and, in many specimens, on metasomal tergum 1 brown ( Fig. 1 ); face and clypeus straw coloured ( Fig. 14 ) (metasomal tergum 3 is as pale as preceding tergum, but appears brown due to telescoping of the more apical segments under it). Appendages straw coloured ( Fig. 1 ); brown on mesotarsomere 5, metatarsomere 5 and in apical 0.5 of metatibia; flagellum fading to brown in apical half. Forewing clear except for two lightly coloured bands (in old specimens bands not visible) aligned with 1 st discal cell and below apical 0.7 of stigma ( Figs. 1 , 50, 55 ) (apical band fading to clear toward apex); radial cell clear but surrounded by apical dark band. Veins light straw coloured except for brown on forewing veins 1M, 1cu­a, RS and R1, and on apical 0.7 of stigma.

Structure. Flagellum with 13 (87% of specimens) or 14 (13% of specimens) flagellomeres. Clypeus with two short and blunt teeth along anterior margin near middle ( Fig. 14 ). Length of gena behind eye 1.2–1.6 times as long as length of eye. Height of eye 1.4–1.6 times as long as minimum distance between inner eye margins. Maximum width of head behind eyes subequal (0.98–1.02) to maximum head width at eye level. Occipital carina in dorsal 0.3 developed or reduced gradually (often outlined with transverse and parallel microsculpture on gena near carina). Mesoscutellar fovea about 2–3 times as wide as long and with about 2–8 septa ( Fig. 40 ). Metasomal tergum 1 with lateral margins slightly convergent (posterior margin 1.3–1.7 times as wide as narrowest width near base), elongate (length 2.3–2.6 times as long as maximum width), and not meeting ventrally in anterior 0.3 ( Fig. 69 ). Vein RS+M absent or at most a stub. Basal cell of forewing with about 10–40 setae usually restricted to apical 0.5 of cell ( Figs. 50, 55 ), clearly less setose than 1 st discal cell ( Fig. 53 ). Subbasal cell of hind wing narrow: vein 1M 3.0 times as long as vein cu­a ( Fig. 65 ).

Sculpture. Punctures on vertex, frons and mesoscutum about 10 µm in diameter (similar to diameter of ommatidia). Punctures 20–60 µm apart on vertex and frons, 30–60 µm apart on mesoscutum, 60–80 µm apart on mesopleuron except posteroventrally where often 10 µm apart, as on face and legs. Clypeus generally glabrous except for row of long setae along anterior margin. Notaulus not outlined in anterior 0.5 or outline suggested by wide impression ( Fig. 40 ). Metasomal tergum 1 with about 6–8 longitudinal ridges, but these anastomosing distally and forming a puncture­like sculpture (as in Fig. 67 ).

Frons and anterior portion of vertex usually with clearly outlined isodiametric meshes of microsculpture (about 7 µm in diameter), sculpticels slightly convex. Discal portion of mesoscutum in posterior half with microsculpture forming irregular transverse and convex ridges ( Fig. 40 ). Ventral 0.5 of mesopleuron punctate or with parallel ridges slanted downward anteriorly and slanted horizontally posteriorly, in few specimens a mixture of both types of sculpture. Remaining body surface smooth or almost so.

MALE. Colour. Propodeum and posterior section of metathorax very light reddish brown.

Structure. Height of eye subequal to minimal distance between eyes: 0.98–1.1 times as long as minimum distance between inner eye margins. Otherwise colour, structure and sculpture as in female.

Taxonomic notes. Much time was spent trying to understand what was L. trigonotylidis . Adults simply could not be segregated from those of L. lygivorus . Loan (1970) thought that L. lygivorus was a univoltine species attacking the second generation of Lygus lineolaris , but Lachance et al. (2001) showed that it was a bivoltine species. Loan (1974a) thought that L. trigonotylidis was a univoltine species attacking Trigonotylus caelestialium (Kirkaldy) (Stenodemini) in early spring. It was not noted that all his type specimens, except for one that was reared, were field swept. A closer look at the reared specimen resolved this problem. The type series of P. trigonotylidis consists of two species. Except for the reared specimen, all others including the holotype belong to L. lygivorus . The reared specimen is L. uniformis . This last species has been recorded previously from T. caelestialium .

Specimens from La Corne in northern Quebec were included, despite a 500 kilometre gap to the next locality in southern Quebec and Ontario. We intensively sampled many sites from the Ottawa River to 160 km north of it over many years and failed to find this species. This range is reminiscent of species associated with clay soils. Because of the number of specimens and the sex ratio observed in the sample, the La Corne specimens were collected probably at peak time of abundance. Adults of the population match perfectly the cycle of P. otaniae , a species clearly associated with Lygus . Despite the abundance of specimens of Leiophron in our sample, we failed to find any among the 20 dissected cocoons reared from Lygus borealis . Though, more field work is needed to better understand the La Corne population, it is best to include the population under L. lygivorous .

Adults of L. lygivorus are most similar to those of L. uniformis and differ by the microsculpture development on the posterior half of the mesoscutum disk, and the host range. A summary of measurement differences between L. lygivorus and L. uniformis is given in Table 2.

Adults of L. lygivorus differ from those of L. australis by the body colour pattern, and forewing venation. Because only one male and one female are known, the measurements in Table 1 are not discussed further.

Adults of L. lygivorus differ from those of L. simoni by the forewing venation, notauli development, and the anterior mesoscutellar fovea proportions. A summary of measurement differences between L. simoni and L. lygivorus is given in Table 3.

Host and biological notes. Reared specimens have been recorded only from Lygus lineolaris . Around Ottawa and southern Quebec adults occur from the third week of May to mid August and with two peaks of abundance from late May to mid June and early August. This is a bivoltine species ( Lachance et al. 2001). It seems that sites with red clover yielded most of the specimens collected.

Material examined and range. 138 (50♂, 88♀) adults were studied. Of these, 67 were reared from Miridae and 71 were field collected. The species is known from cold temperate regions of eastern North America between North Dakota and Prince Edward Island .

CANADA. ON: 3 km E Fitzroy (3♀) ; Foxboro (1♀) ; Fuller (1♀) ; Guelph (30♂, 7♀) ; 5 km E Kinburn (4♂, 8♀) ; Marlborough Forest (1♀) ; 3 km SE Mountain (3♀) ; Ottawa , 45º23'28"N 75º42'52"W (3♂, 13♀; CNCI USNM) ; Ste. Catherine (1♂, 1♀) ; Sidney (3♂, 13♀) ; Talbotville (1♀) ; Wallbridge (2♀; USNM) . PE: Harrington (2♀) . QC: 1 km N La Corne (6♂, 12♀) ; 4.5 km E Hemmingford (1♀) ; Hemmingford , James Fisher Road (1♀) ; Iberville (2♂, 3♀) ; Mt. St. Hilaire (1♀) ; Ste. Clotilde (1♂, 11♀) . USA. IA: Ames (1♀; USNM) . ND: Elk Point (1♀; USNM) .

Figures

FIGURES 1–5. Habitus with frontal view of head. Codes: “a” clypeal colour; “b” metatibial colour; “c” metacoxal colour; “d” forewing colour; “e” mesoscutal colour.

FIGURES 13–24. 13–22. Frontal view of head. Code: “a” ventral edge of clypeus. 23–24. Dorsal view of head.

FIGURES 50–58. 50–52. Forewing. 53–54. Basal and subbasal cells of forewing. 55–58. Radial cell and stigma of forewing.

FIGURE 37–49. 37. Lateral view of antenna. 38–39. Last six flagellomeres in lateral view. 40–44. Dorsal view of mesosoma. 45–49. Lateral view of mesosoma.

FIGURES 67–78. 67–68. Dorsal view of metasomal tergum 1. 69–70. Ventral view of metasomal segment 1. 71–72. Lateral view of seven last flagellomeres. 73–74. Lateral view of first three flagellomeres. 75–76. Dorsal view of protarsus. 77–78. Lateral view of metasoma.

FIGURES 59–66. 59–63. Radial cell and stigma of forewing. 64. Hind wing. 65–66. Basal and subbasal cells of hind wing.