Review of the Nearctic species of Leiophron and Peristenus (Hymenoptera Braconidae: Euphorinae) parasitizing Lygus (Hemiptera: Miridae: Mirini:)
Author
Goulet, Henri
Author
Mason, Peter G.
text
Zootaxa
2006
2006-09-28
1323
1
1
118
https://biotaxa.org/Zootaxa/article/view/zootaxa.1323.1.1
journal article
10.11646/zootaxa.1323.1.1
11755334
5071178
071E8D92-514B-4E2B-9F3F-E085CACA976A
Peristenus howardi
Shaw
(
Figs. 59, 60
, Table 17)
Peristenus howardi
Shaw, 1999: 371
. Type locality:
USA
:
Idaho
,
Canyon Co.
, Parma.
Holotype
, female (ESWU), not seen, labelled: “
Idaho
,
Canyon County
,
Parma
,
4 August 1997
,
C. R. Baird
, host:
L. hesperus
Knight
nymph swept in alfalfa, emerged
3 September 1997
.
Diagnosis.
Clypeus black or dark brown, not densely punctate (especially between lateral ocellus and inner eye margin), forewing vein r generally absent, and a multivoltine life cycle associated with all generations of
Lygus
.
Description.
FEMALE. Colour. Head, mesosoma and metasoma black. Legs generally straw coloured, metacoxa brown to black; basal 0.3–0.5 of metatibia usually straw coloured or occasionally light reddish brown, and apical 0.5–0.7 of metatibia, and metatarsomere 1 clearly darker than basal 0.3–0.5 of metatibia, but metatarsomeres 2–5 less dark than metatarsomere 1. Palpi, tegula and mandible (except apex) straw coloured. Scape to flagellomere 2 straw coloured, thereafter brown to dark brown. Stigma dark brown and straw coloured in basal 0.3.
Structure. Flagellum with 18–20 flagellomeres (respectively 12%, 73% and 12% of
17 specimens
) and flagellomeres enlarged in apical 0.5. Few of the preapical flagellomeres subquadrate (none 3%, one 15%, two 9%, three 29% and four 44% of
34 specimens
). Length of gena behind eye 0.91–1.09 times as long as length of eye. Height of eye 1.34–1.52 times as long as minimum distance between inner eye margins (as in
Fig. 18
). Maximum width of head behind eyes subequal (0.93–0.97) to maximum head width at eye level. Occipital carina developed in dorsal third. Metasomal tergum 1 with lateral edges clearly convergent (posterior margin 2.1–2.4 times as wide as narrowest width near base) and elongate (medial length of tergum 1.5–1.7 times maximum width at posterior end). Radial cell length 0.94–1.13 as long as stigma width (as in
Figs. 58–63
). Forewing vein r in most specimens not developed (78% based on
100 specimens
) and short (
Fig. 59, 60
), and basal cell of forewing (except extreme base) pubescent (as in
Fig. 54
).
Sculpture. Punctures on vertex
5–10 µm
in diameter, on frons and mesoscutum about
10–15 µm
in diameter (a little larger than diameter of ommatidia). Punctures
20–25 µm
apart on vertex (especially between lateral ocellus and inner eye margin),
5–15 µm
apart on frons to
5–10 µm
apart near antennal socket, and
20–25 µm
apart on mesoscutum. Punctures on mesopleuron generally dense, occasionally scattered. Clypeus generally smooth, rarely punctate all over. Metasomal tergum 1 with about 10–12 longitudinal ridges, these often anastomosing on disc and forming a puncturelike sculpture.
MALE. Unknown.
Taxonomic notes.
The
holotype
was not seen, but several specimens reared in a laboratory colony in
Delaware
originating from the type locality have been studied. The lack of r vein in the forewing, discovered by Shaw (
Day
et al
. 1999
), applies to the
holotype
. The character is not seen in all specimens of this species studied and it also shows up frequently in adults of closely related species. Nevertheless, evidence discussed below supports its specific status.
Adults of
P. howardi
are most similar to those of
P. broadbenti
. Almost no structural differences were found between
P. howardi
and
P. broadbenti
. Adults of
P. howardi
differ from those of
P. broadbenti
in the development forewing vein r, the lack of males, and a multivoltine life cycle. A summary of measurement differences between
P. broadbenti
and
P. howardi
is given in Table 17.
Almost no structural differences were found between
P. howardi
and
P. gillespiei
. Adults of
P. howardi
differ from those of
P. gillespiei
in the development of the forewing vein “r”, males unknown, and the multivoltine life cycle. A summary of measurement differences between
P. howardi
and
P. gillespiei
is given in Table 17.
Adults of
P. howardi
could easily be confused with those of
P. braunae
a darkly coloured species. They are easily distinguished from those of
P. braunae
by the colour of the clypeus and metatibia, by the puncture density on the vertex especially between the lateral ocellus and the inner eye margin, by the the ratio of eye height to minimal distance between eye inner margins, and the ratio of length of flagellum to maximum width of head between outer eye margins.
Host and biological notes.
Adults of
P. howardi
have been reared from fieldcollected
Lygus hesperus
and in the laboratory on
L. lineolaris
(
Day
et al
. 1999
)
. Adults occur from early May to late September with peaks of abundance probably in mid June, late July, and early September. This is a multivoltine species. Females of this species parasitize nymphs of all generations of
Lygus
.
Material examined and range.
56 (
56♀
) adults were studied. All were reared from
Miridae
. The species is known from the northern portions of the Great Basin in
Idaho and Washington
.
USA
. DE:
Newark
,
Laboratory
colony from ID,
Canyon Co.
,
Parma
(
52♀
;
CNCI
,
USDA
,
USNM
)
.
ID:
Canyon Co.
,
Parma
(
5♀
, not seen;
ESUW
)
.
WA:
Benton Co.
, EWSU
Exp. Station
N of Prosser
(
4♀
;
ESWU
,
CNCI
)
.