REVISION OF THE NEARCTIC SPECIES OF METACLISIS FOERSTER (HYMENOPTERA, PLATYGASTRIDAE, INOSTEMMATINAE)

Abstract The Nearctic species of the genus Metaclisis are revised. Of 18 species recognized, 16 of them new to science as follows: M. acericola (Quebec, Ontario), M. acerina (Quebec, Ontario, Illinois), M. aceris (Quebec, Ontario), M. acuta (Arizona), M. alticola (New Mexico), M. annae (Texas), M. attenuata (California), M. borealis (Labrador), M. ensifer (California), M. filicornis (Ontario), M. longula (Illinois, Maryland, Ontario), M. masoni (Manitoba), M. pumilio (Ontario, Quebec, Illinois, Maryland, N. and S. Carolina), M. sulcata (Eastern Canada and U.S.A., Tennessee), M. verna (Ontario), and M. vernalis (Quebec, Ontario, Maryland). M. carinata (Ashmead) ♀ and M. floridana (Ashmead) ♂ are redescribed and the male of M. floridana is newly described. A generic diagnosis of Metaclisis and keys to females and males of Nearctic species are given. The higher classification, bionomics, world distribution, and character states of Metaclisis species are discussed. Résumé L’auteur révise les espèces néarctiques du genre Metaclisis. Parmi les 18 espèces reconnues, 16 sont nouvelles, soit M. acericola (Québec, Ontario), M. acerina (Québec, Ontario, Illinois), M. aceris (Québec, Ontario), M. acuta (Arizona), M. alticola (Nouveau Mexique), M. annae (Texas), M. attenuata (Californie), M. borealis (Labrador), M. ensifer (Californie), M. filicornis (Ontario), M. longula (Illinois, Maryland, Ontario), M. masoni) (Manitoba), M. pumilio (Ontario, Québec, Illinois, Maryland, Caroline du Nord et du Sud), M. sulcata (est du Canada et des États-Unis, Tennessee), M. verna (Ontario) et M. vernalis (Québec, Ontario, Maryland). M. carinata (Ashmead) et M. floridana (Ashmead) sont redécrits et le mâle de M. floridana est décrit pour la première fois. L’auteur présente un diagnostic générique Metaclisis et des clefs d’identification des femelles et des mâles de certaines espèces néarctiques. Il étudie la classification supérieure, la bionomie, la répartition mondiale et la manifestation des caractères d’espèces de Metaclisis.

The members of Metaclisis may be recognized among all genera of the Inostemmatinae by having cheeks with strong fan-like striae, and by the presence of a rudimentary basal vein in fore wing, and at least partly extruded and fully sclerotized apices of ovipositor sheaths in the female. The striate cheeks seem to be the most reliable character as the basal vein may be very pale to almost inconspicuous in some species and the sheaths are often retracted into the metasoma. The striate cheeks will also distinguish Metaclisis in South America from Proplatygaster Kieffer, the members of which also have better developed wing venation.
Eurostemma Szeltnyi may be congeneric with Metaclisis; however, I was not able to examine the type of Inostemma europus Walker, the type-species of the former genus. Kozlov (1970) proposed a monotypic tribe to accommodate Metaclisis in the system of the Inostemmatinae. He stressed the presence of the basal vein and the forked apex of the submarginal vein in the fore wing, i.e. characters occurring also in several undescribed inostemmatine genera not related to Metaclisis. I prefer not to use tribal names in the Inostemmatinae until the subfamily is better studied.
The present world distribution of Metaclisis comprises the entire temperate zone of both the Palearctic and Nearctic regions, the mountains of Central and South America, and the temperate zone of South America. Several species were described from Europe (Kieffer 1926;Maneval 1936;Debauche 1947;Tomsik 1950;Szab6 1959), two from North America (Ashmead 1887(Ashmead , 1893 and one from Chile (Walker 1842). Szabo (1959) also reported an undescribed species from Argentina. I have examined an abundance of exotic material of Metaclisis in the Canadian National Collection (CNC). Numerous undescribed species were collected from central Mexico to Costa Rica, Honduras, Jamaica, Colombia, Ecuador, Peru, and Chile. The species in tropical regions were confined to higher altitudes, montane rain forest, cloud forest, elfin forest, or eventually the paramo formation near the equator. An interesting correlation exists between wing development and altitude among the Neotropical species of Metaclisis. The first response to higher altitude is the infuscation of the wings (cloud forest), next is a stronger infuscation combined with abnormally enlarged wings (elfin forest), and finally microptery or loss of wings with a simultaneous reduction of the pterothorax and massive development of the hump between T1 and T2 (paramo region).
The hosts of Metaclisis are not known but are believed to be gall forming species of the Cecidomyiidae. Mr. H. J . Vlug (Wageningen) (in litt.) reared in Holland an undescribed species from cecidomyiid larvae in flowers of birch (Betula sp.). During my field work in 1979-1980 I associated several Nearctic species of Metaclisis with sugar maple (Acer saccharum Marsh.) by observing adult wasps on leaves in the second half of May in Ontario and Quebec. Here they could be easily swept in large numbers along with two vernal species of Acerotella Msn. (Masner 1980b). Other records involving Nearctic Metaclisis show species of oak (Quercus), willow (Salix), and goldenrod (Solidago) as potential associations. All of these plants are hosts of many species of Cecidomyiidae. The majority of the Nearctic species of Metaclisis appear in spring; during March-April in the Lower Austral, May in the Transitional and Canadian, and June-July in the Hudsonian zones respectively. So far only species, viz. M. sulcata n. sp. (associated with goldenrod) was recorded only in summer and fall.
Individuals of Metaclisis are rare in collections (e.g. Szabo 1959). However, during only 2 years I was able to amass some 400 individuals representing numerous undescribed species. The alleged rarity of these wasps is possibly caused by two interesting biological phenomena, viz. an apparent short life span of the adults and their rigid adherence to respective host plants. While observing the habits of the complex associated with sugar maple in Quebec and Ontario, I noticed that the adults appeared, peaked and disappeared usually within a week, the males always preceding the females in appearance. This seems to be an ecological correlation well synchronized with a rather rapid postembryonic development of the presumed host, Dasineura sp. (? communis Felt), the galls of which will develop, mature, and drop off the leaves within 2 weeks (R. Gagnt, USDA, Washington, pers. comm.).
Both the host and the parasite will not appear again until the next spring. Thus the adult wasps may be encountered only once a year during a very short period. Furthermore, the adult wasps seem to be strictly confined to their niche, i.e. the leaves of the host plant. When disturbed by sweeping they fly around very little, returning soon to the original site. I failed to catch them with either Malaise or pan traps, even in situations where the traps were set right next to host plants. Sweeping of respective host plants at daily intervals during the short flight period of each species is the only productive method of collecting members of Metaclisis.
The 18 Nearctic species, based on some 400 individuals treated in this paper, certainly do not represent the entire North American fauna. The relatively high number of species based on single specimens or short series indicates that much is left to be discovered in this genus. More species are likely to be found mainly in the southern parts of the U.S.A. The use of mass collecting methods (e.g. screensweeping) as well as observance of individual wasp-plant associations should be pursued. Host records through rearings are the ultimate goal for correct association of sexes. Unfortunately, at this moment only seven Nearctic species are known from both sexes. The considerable degree of sexual dimorphism in Metaclisis precludes ready association of sexes.
A classification of the 18 Nearctic species into species groups is not attempted at the present time. It will be postponed until a more complete picture of the genus is achieved, with more biological data, etc. However, the three vernal species associated with sugar maple (viz. M . acericola n. sp., M. acerina n. sp., and M. aceris n. sp.) appear to form a distinct group. The unusually long scape in females and the predominant golden colour of antennae and legs in both sexes are quite remarkable.
The proper gender of Metaclisis is feminine as explicitly mentioned by Foerster (1856: 106, footnote **). The subsequent use of a masculine gender by some authors (e.g. Muesebeck and Walkley 1956, HellCn 1968, Kozlov 1978) is incorrect. Character states, measurements, and abbreviations. The Nearctic members of Metaclisis appear to be a morphologically very homogeneous complex. Relatively few characters appear to be diagnostic, and such as the antennae are highly dimorphic sexually. Therefore, separate keys to females and males are necessary. Useful cephalic characters appear to be the following: general shape and lengthlwidth ratio of head, with cephalic measurements from dorsal view (head termed transverse if wider than long); mutual ratios of eye height, interorbital space, and length of scape, where eye height is measured from lowermost to uppermost point of the orbit, the interorbital space is the shortest distance between inner orbits, and the length of scape is measured excluding the radicle. All three measurements are to be done from frontal view. If flexed to the frons the scape may either attain or exceed the vertex (in lateral view). The female antenna offers excellent specific characters, among them the lengthlwidth ratio of A3, the type of clava (semiabrupt to abrupt) depending on' shape of A7, and the location of sensilla on segments of the clava. The male antenna shows relatively less variation; however, the shape of A4 might be exploited later when males are known in most species.
The mesosoma offers relatively few diagnostic characters except in three species where the notauli are quite distinctive. The maximal width of mesosoma is measured across the mesoscutu~ right in front of the tegulae (tegulae are not included as they are partly movable).
The metasoma in the female is of importance second only to the antennae. General shape, lengthlwidth ratio of T2, sculpture of T1 and T2, presence or absence of the hump between T1 and T2, shape of T6 and relative length of S6 compared to length of S3-S5 combined are the most useful characters. However, caution must be exercised in subteneral or poorly preserved specimens in which the metasoma tends to shrink, upsetting the measurements readings. Similarly, the ovipositor sheaths may be retracted or extruded even in normal specimens.

December 1981
The measurements are figured in direct readings of an ocular scale at 160X; they represent fractions of 1 mm, with 100 equal to 1 mm. Direct readings are preferred over the x:l ratios in order to permit mutual comparisons of length and width of individual parts of the body (e.g. length of scape vs. length of T2).
The morphological terms and their respective abbreviations used in this paper are those proposed by Masner ( 1 9 8 0~) . Measurements of antennal segments given in "relative proportions7' refer to maximal length divided by maximal width of the object.  Masner (1965).
Moderately to distinctly elongate forms, with body sometimes slightly depressed dorsoventrally. Head transverse, subellipsoidal, rarely subrectangular; cheek with fan of striae radiating from base of mandible and reaching sometimes to lower frons; subocular suture and a corresponding keel between lower orbit and base of mandible present or obscured by striae; mandible bidentate; palpal formula 2-1; clypeus rather narrow, protruding in some species; ocelli in low triangle, OOL shorter than both LOL and POL; eye at least sparsely hairy, in some species with dense erect hairs; occipital carina well developed, often crenulate along inner side; occipital pit absent; antennal formula 10-10, in female clava moderately to strongly abrupt, 3-4 segmented, rarely clava indistinct, in male A4 with outer carina and/or apical-outer corner expanded; notauli percurrent, often dilated posteriorly, strongly converging in front of scutellum; scutellum almost semicircular, with posterior margin rounded, with distinct row of crenulae along anterior margin; mesopleuron with deep declivity in lower half, almost smooth and glabrous; sternaulus absent; acetabular carina well developed; metapleuron always pubescent; metanotum not protruding medially, usually smooth and glabrous; propodeum pubescent, with ^-shaped keel medially; fore wing with long submarginal vein distinctly knobbed apically, knob more or less forked, often suffused with surrounding infuscation; basal vein usually faint, indicated at most as a darker pigmented streak; medial, radial, and cubital veins rarely indicated as darker lines; marginal cilia very short; hind wing with a short stub of submarginal vein; tarsal formula 5-5-5; tibia1 spur formula 1-2-2; metasoma in females moderately to strongly elongate, at least as long as head and mesosoma combined, with 6 visible tergites and 6 sternites, T1 without horn but often humped at junction with T2, T6 triangular, pointed at apex, ovipositor sheaths at least partly exposed and sclerotized; metasoma in males with 7 visible tergites.
Mesosoma as high as wide (45:45), with dense short silvery pilosity; mesoscutum coriaceous-punctate; notauli strongly convergent and distinctly dilated posteriorly, not crenulate at bottom; scutellum finely coriaceous; fore wing attains only to base of T6; basalis and proximal part of medialis distinctly pigmented; legs relatively short and stout, with hind basitarsus only 4.5 times as long as wide.
Metasoma elongate, distinctly longer than head and mesosoma combined (120:85), sharply pointed apically; junction of T1 and T2 humped; T1 with short costae in anterior half, with posterior half smooth; T2 with strong longitudinal striae reaching at sides at least to basal half of the tergite, striae less developed anteromedially; posterior half of T2 with very fine coriaceous sculpture (160x, seen at angle); T2 slightly shorter than T3-T6 combined (5255); T3-T5 finely coriaceous, with at least two rows of dense silvery hairs each; T6 elongate, longer than wide (35:18), longer than T3-T5 combined (35:20), finely coriaceous in anterior third, almost smooth in posterior two-thirds, covered with scattered long silvery hairs; S6 longer than S3-S5 combined, entirely rugulose, with silvery hairs; ovipositor sheaths about as long as hind basitarsus. REMARKS. The female of M. masoni is one of the most unusual among those of Nearctic species of Metaclisis. The rough sculpture of the head, dense silvery pilosity of the body, striation of T2, and shape of both T6 and S6 are truly unique combinations of character states. The species is named in honour of its collector, Dr. W. R. Mason (BRI, Ottawa).
Metasoma elongate, distinctly longer than head and mesosoma combined (95:55), sharply pointed apically; junction between T1 and T2 humped; T1 with only minute costae along anterior margin, otherwise smooth; T2 with minute costae along anterior margin, with anterolateral foveae shallow, non-striated, and almost glabrous, with rest of the tergite smooth and mirror-like, the tergite longer than wide (43:35), longer than T3-T5 combined (43:lS); T3-T5 with very fine coriaceous sculpture, with one row of hairs each; T6 smooth, distinctly elongate, longer than T3-T5 combined (23:15); S6 smooth, distinctly longer than S3-S5 combined (30: 17); ovipositor sheaths as long as hind tibia. REMARKS. The unusually long T6 and S6 in combination with narrow notauli and short costae on T2 will sufficiently characterize the female of this species among those of the Nearctic species of this genus. The name of this species refers (in Latin) to the sharply pointed apex of the metasoma.
Mesosoma as high as wide (35:35), only slightly arched dorsally, with dense minute pilosity; mesoscutum with fine coriaceous sculpture; notauli distinctly dilated posteriorly, not crenulate at bottom scutellum with coriaceous sculpture somewhat finer than in mesoscutum; fore wings reaching well to tip of metasoma; basal vein almost inconspicuous, very pale; other veins not indicated.
Metasoma as long as head and mesosoma combined (65:65), rather short and stout, not humped at junction of T1 and T2; T1 entirely costate; T2 slightly longer than wide (38:35), longer than T3-T5 combined (38:15), with strong longitudinal costae in anterior '13 and finer longitudinal striae extending over the basal half; anterolateral foveae of T2 shallow, with few hairs; T3-T6 with delicate coriaceous sculpture and with one row of hairs each; T6 triangular, as long as wide (13:13) REMARKS. The female of M. filicornis is one of the most unusual among those of Nearctic species, with its antenna almost filiform, with no distinct clava, and with sensilla on A9 and A10 only. The Latin name of this species refers to its slender, almost thread-like antennae.
Mesosoma only slightly wider than high (43:41), moderately arched dorsally, with dense minute silvery hairs; mesoscutum with fine coriaceous sculpture; notauli distinctly dilated posteriorly, not crenulate at bottom; scutellum with sculpture finer than in mesoscutum; fore wings reaching to tip of metasoma; basal vein almost inconspicuous, pale, other veins not indicated.
VARIABILITY. The body size varies between 1.0 and 1.5 mm. The smaller individuals tend to have sculpture of frons (between anterior ocellus and antenna1 insertion) very fine to almost partly smooth. Similarly, the striae on T2 are shortest in smallest individuals.
REMARKS. The female of M. vernalis is distinct in its antenna having a strongly elongate A3 in combination with moderately transverse segments of the clava. The male resembles to some extent that of M. carinata (Ashm.); however, it may be distinguished by having A1 distinctly longer than interorbital space. 6. Metaclisis acericola n. sp. Female. Length 1.25 mm. Body dark brown to black, head and mesosoma darker than metasoma; antenna bicolor, with radicle and A1-A7 bright golden yellow, and A8-A10 light brown; fore legs (including coxae) entirely golden yellow, middle legs light brown with golden coxae, hind legs including coxae light brown; mandibles and tegulae yellowish brown; wings slightly infuscate, with venation pale.
Head transverse (21:39), as wide as mesosoma across tegulae; vertex and occiput with coriaceous sculpture; frons with sculpture becoming finer immediately below anterior ocellus, lower frons above toruli with longitudinal concentric striae; cheeks heavily striate, however, striae not obscuring a strong keel connecting lower orbit of eye with base of mandibles; occipital carina strong, distinctly crenulate; clypeus prominent (in lateral view), with sharp anterolateral corners; eyes distinctly hairy; eye height interorbital space and scape in ratios 16:22:30; OOL as long as diameter of posterior ocellus; temples behind eyes (dorsal view) strongly receding; A1 (scape) when flexed to frons with apex distinctly surpassing vertex; antenna as in Fig. 3; A10 with sensillum well below apex.
Mesoscutum slightly wider than high (39:35), in lateral view only slightly arched dorsally; mesoscutum with coriaceous sculpture and scattered minute punctures; notauli percurrent, distinctly dilated in posterior half, not crenulate at bottom; scutellum with coriaceous sculpture; fore wing widely surpassing tip of metasoma; basal and median veins in fore wing very pale.
Metasoma only slightly longer than head and mesosoma combined (75:60), not humped at junction T I and T2; T I trapezoidal, twice as wide as long (20:10), longitudinally costate all over; T2 only slightly longer than wide (45:42), campanulate, with strong longitudinal costae at base and continuing longitudinal striae well over the basal half, with finer striation exceeding medially into posterior third of the tergite; T3-T6 almost smooth, with one row of silvery bristles each; ovipositor sheaths only partly exposed.

Male. Differs from female in following characters. Antenna uniformly golden yellow; A1
(scape) in lateral view (when flexed to frons) with apex not exceeding the level of vertex; A4 moderately expanded distally, with percurrent carina outwardly, however, outer apex of segment not hook-like expanded; A5-A9 slightly elongate (6:5), A10 twice as long as wide. BIOLOGY. The host is unknown but is presumed to be a common gall forming cecidomyiid associated with sugar maple, such as Dasineura communis Felt. Adult wasps were collected on maple leaves during a relatively short period, usually a few days in the second half of May. The wasps were caught in abundance by either sweeping or beating with a sheet on young seedlings or lower branches of sugar maple. The above biological features seem to be shared by two other Nearctic species of Metaclisis associated with sugar maple, viz. M. acerina n. sp. and M . aceris n. sp. VARIABILITY. In specimens examined the total body length varies between 1.2 and 1.6 mm. The sculpture of frons (below anterior ocellus) tends to be coarser in larger, and finer in smaller individuals. Similarly, the striae on T2 are relatively longest in largest individuals and vice versa. The colouration of antennae and legs appears to be rather constant.
REMARKS. M. acericola n. sp. may be easily distinguished from both M. acerina n. sp. and M. aceris n. sp. by having a sculptured frons and longer striae on T2 in both sexes, and by the shape of A10 and the position of its sensillum in the female.
Individuals of A. acericola are also generally larger than those of the two above species. The Latin name of this new species indicates the close association with maple (Acer) . VARIABILITY. Only little variation in body size has been observed. Some individuals have legs, scape, and distal half of antenna light brown. In some individuals the striae on T2 do not reach the basal third of the tergite, while in others they slightly exceed that line.

. Metaclisis acerina n . sp.
REMARKS. This species may be distinguished from M. aceris n. sp. only in the female sex: the antenna is generally more slender in M. acerina, with A5-A9 distincily elongate, and only A8-A10 have sensilla. The name of this species indicates the close association with maple (Acer). BIOLOGY. The host is unknown. Field data indicate a cecidomyiid host associated with sugar maple as with the two preceding species.

Metaclisis aceris n. sp.
VARIABILITY. In specimens examined the body size varies between 9.0 and 1.3 mm.
REMARKS. M. aceris may be distinguished from M. acerina only in the female sex by characters mentioned in both the key and the description above. The name of this species indicates the close association with maple (Acer).
The original description is rather laconic, incomplete, and in some respects incorrect. The redescription is based on the holotype and a perfectly matching female specimen from Maryland (see Material).
Female. Length 2.1 mm. Black; trochanters, knees and tarsi light brown, apex of fore femur and the fore tibia even lighter; fore wing almost clear, with submarginal vein dark brown.
Metasoma short, as long as head and mesosoma combined; T1 entirely costate, not humped at junction with T2; T2 with heavy parallel costae reaching medially almost to apex of tergite leaving here a narrow smooth strip not longer than T3: T3-T5 finely coriaceous, with one row of hairs each; T6 almost smooth, wider than long (20:16); ovipositor sheaths shortly extruded. Male (new description). Differs from female by following characters. Legs generally lighter, with fore legs and antennae yellowish brown; antenna with very short flagellum, A5-A9 distinctly transverse; T2 with striae slightly shorter than in female. MATERIAL EXAMINED. Holotype ? (USNM, No. 2860) "Jacksonville Fla.", "Type", "Collection Ashmead", red tag "Type No. 2860 USNM", "Acerota floridana DISTRIBUTION. Infrequently collected but apparently widespread eastern species. Specimens were examined from Florida, Illinois, Michigan, Quebec, and Ontario. BIOLOGY. The host is unknown but presumed to be some larger species of gallforming Cecidomyiidae. Adult wasps were collected mostly during the second half of May. There seems to be only one generation per year. VARIABILITY. Individuals examined varied in body size from 1.5 to 2.5 mm. A short median furrow situated between the notauli in front of scutellum was observed in one female.  Head transverse (20:40), with dense silvery hairs; occipital carina complete, with minute crenulae; occiput, vertex, and frons with fine coriaceous sculpture; cheeks with short fan-like striae, not extending to frons; keel between lower orbits and base of mandibles rather fine; eye height, interorbital space, and scape in ratios 17:24:24; eyes with short hairs; OOL 1.5 times as long as ocellar diameter; temples behind eyes less receding than in M. alticola; antenna ( Fig. 5) with non-abrupt, rather slender 3-segmented clava, with A3 twice as long as wide.
Metasoma slightly longer than head and mesosoma combined (75:65), not humped at junction of T I and T2; T1 longitudinally costate; T2 slightly longer than wide (42:37), distinctly longer than T3-T6 combined (42:28), with short costae basally, costae at meson not longer than length of T I , and with longer, finer striae anterolaterally, almost smooth in remaining part but with submicroscopic coriaceous sculpture (to be examined at angle, 160x); anterolateral foveae deep, longitudinally striate; T3-T5 with delicate coriaceous sculpture and one row of hairs each; T6 only slightly wider than long (14:12); S6 as long as S3-S5 combined (13: 13); ovipositor sheaths not extruded. Male. Differs from female in having fore wings twice as long as metasoma (115:50), metasoma shorter than head and mesosoma combined (50:60), and in structure of antennae, with A5-A9 moderately elongate (5.5:3.5), A4 only slightly expanded apically, with longitudinal outer carina. TYPE MATERIAL. H o l o t y p e : Q ( C N C N o . 1 6 4 8 7 ) , C a n a d a , H e b r o n (Newfoundland-Labrador), August 10 1954, on Salix, J.F. McAlpine (left antenna on slide). Allotype: 8, with same data as holotype but caught August 9 o n dandelion (Taraxacum) (CNC). Paratypes: 3 Q Q , with same data as holotype but caught August 5 and 9 on Salix and Taraxacum (CNC). DISTRIBUTION. Newfoundland (Labrador). BIOLOGY. The host is unknown but is expected to be a cecidomyiid associated with willow (Salix).
VARIABILITY. NO substantial variability was encountered in the type series. REMARKS. Specimens of M. borealis may be compared with those of M. alticola because o f the unusually long fore wings. However, they may be distinguished from one another by different structure of metasoma and length of A 3 in female sex. The Latin name o f this new species refers to its northern distribution.
Metasoma distinctly longer than head and mesosoma combined (1 10:60), attenuate, distinctly humped at junction of T I and T2; T I almost vertical due to development of hump, with only minute costae along anterior margin medially, smooth at meson, with fine longitudinal striation at sides; T2 distinctly elongate (56:33), longer than T3-T6 combined (56:53), with fine striae basally and fine continuation of striae up about the middle of the tergite; T3-T5 with fine coriaceous sculpture, with one row of hairs each; T6 smooth, longer than wide (12: 10); S6 triangular, elongate (25: 14), shorter than S3-S5 combined (25:33); ovipositor sheaths long, extruded. VARIABILITY. The striae on T2 are shorter and less expressed in the paratype. T3-T6 are slightly shorter in the paratype, may be retracted due to long storage of type material in alcohol.
REMARKS. The female of M. attenuata is quite peculiar among those of all Nearctic species of Metaclisis in having T2 almost twice as long as wide. Traces of radial and cubital veins (by darker lines) in fore wing are also diagnostic. Surprisingly, S6 is relatively short in combination with strong development of hump between T1 and T2. The name (in Latin) refers to the long, narrow metasoma in this species.
12. Metaclisis pumilio n . sp. Fig. 8 Female. Length 0.9 mm. Dark brown to black; antennae and legs brown, with fore tibiae, knees and tarsi of all legs yellowish brown; wings almost clear, with submarginal vein light brown.
Head only slightly transverse (17:26), almost subrectangular, with rather dense silvery hairs; occipital carina complete, though delicate at meson, with no distinct crenulae; occiput and vertex (interocellar triangle) with delicate coriaceous sculpture; temples and frons almost entirely smooth, shining, with no sculpture below anterior ocellus; cheeks with short and rather delicate fan-like striae; keel between lower orbit and base of mandibles delicate; eye height, interorbital space, and scape in ratios 12:16:15; eyes with rather long hairs; OOL slightly less than ocellar diameter; temples behind eyes at first almost straight and then receding; antenna short ( Fig. 8), with rather abrupt 3-segmented clava, with A3 only slightly longer than wide (2.2:2).
Metasoma rather short, only slightly longer than mesosoma and head combined (50:40), with no hump at junction of T1 and T2; T1 smooth except for extremely short costae along anterior margin; T2 slightly longer than wide (30:28), almost twice as long as T3-T6 combined (30:16), with fine striae anteromedially, striae not longer than T I , smooth in the remaining part, with anterolateral foveae finely striate and pilose; T3-T6 smooth, with one row of hairs each; T6 broadly triangular, wider than long (1 1:6); S6 shorter than S3-S5 combined (8:13); ovipositor sheaths retracted. VARIABILITY. The length of body varies from 0.8 mm to 1.2 mm. The larger individuals tend to have striae on T2 better developed, longer than T I , head slightly more transverse and temples more receding than the smaller specimens. REMARKS. Females of M. pumilio are the smallest among Nearctic species of Metaclisis. The subrectangular shape of head, with temples partly parallel behind eyes, the smooth frons and scutellum, and the relatively long marginal cilia in fore wing are diagnostic characters. The Latin name of this species refers to small size of its females.
Metasoma elongate, slightly longer than mesosoma and head combined (60:50), with no hump at junction of T1 and T2; T1 with short costae in anterior half, smooth in posterior half; T2 longer than wide (31:28); longer than T3-T6 combined (31:25), with anterior costae only as long as half of T1 and with some finer striae not exceeding the '14 of the tergite, smooth in the remaining part, with anterolateral foveae small, hairy; T3-T6 almost smooth, with one row of hairs each; T6 triangular, wider than long (12:lO); S6 shorter than S3-S5 combined (12:17); ovipositor sheaths long extruded, as long as half of hind tibia.

December 1981
Male. Differs from female in structure of antenna and metasoma. A4 with longitudinal outer carina, segment not particularly expanded distally; AS-A9 almost as long as wide, or slightly transverse, A10 elongate (7:3), more than twice as long as A9 (7:

Fig. 10
Female. Length 1.4 mm. Black; antenna dark brown, legs dark brown except for knees and fore tibiae that are yellowish brown; wings slightly infuscate, submarginal vein in fore wing brown.
Head transverse (22:43), with silvery pilosity; occipital carina complete, with minute crenulae; occiput, vertex and frons with coriaceous sculpture, middle of frons with smoother area and with some longitudinal elements medially right above toruli; cheeks with fan of strong striae, keel between lower orbit and base of mandibles rather weak; eye height, interorbital space, and scape in ratios 16:25:25; eyes with scattered hairs; OOL as long as ocellar diameter; temples behind eyes strongly receding; antenna ( Fig. 10) with rather abrupt 4-segmented clava.
Mesosoma as high as wide (41:41), rather arched dorsally, with scattered appressed silvery hairs; mesoscutum and scutellum with fine coriaceous sculpture; notauli gradually dilated in posterior l/3 and here distinctly wider than the height of their incision into mesoscutum; fore wings slightly surpassing the tip of metasoma, the fore wing longer than metasoma (105:65); basal vein vestigial, indicated by darker streak only in its upper part; other veins not indicated.
Metasoma short and stout, shorter than mesosoma and head combined (65:75), not humped at junction of T I and T2; T1 with strong longitudinal costae; T2 slightly wider than long (45:40), distinctly longer than T3-T5 combined (40:17), with strong longitudinal costae in anterior half and delicate coriaceous sculpture in posterior half; anterolateral foveae of T2 very shallow and pubescent; T3-T6 with delicate coriaceous sculpture and one row of silvery hairs each; T6 broadly triangular, wider than long (16:7); S6 wider than long (16:13), shorter than S3-S5 combined; ovipositor sheaths shortly protruding. VARIABILITY. Little variability has been observed in the short type series. One paratype female is only 1 mm long. However, I have six more females (ON, PQ, NY) tentatively assigned to this species that differ in structure of antennae. The A7 is markedly smaller than A8 thus making the club appear almost 3-segmented. I prefer not to include the above series in the type material. REMARKS. The female of M. verna is short and stocky, with short antennae and short metasoma. It resembles smaller individuals of M. JZoridana but is distinguished from the latter at once by shorter costae on T2 and non-crenulate notauli. It is conveniently distinguished from the females of M. vernalis by having relatively short A3. The latin name used refers to the spring season when adults of this vernal species appear for a short period.
Metasoma short, shorter than mesosoma and head combined (45:60), not humped at junction of T1 and T2; T1 partly longitudinally costate; T2 slightly wider than long (35:30), distinctly longer than T3-T6 combined (30:10), with basal striae not longer than length of T1, otherwise smooth, with anterolateral foveae shallow and sparsely hairy; T3-T6 almost smooth, with one row of hairs each; T6 broadly triangular, several times wider than long; S6 distinctly shorter than S3-S5 combined; ovipositor sheaths, extruded, slightly longer than hind basitarsus. REMARKS. The female of M. alticola is distinct among those of all Nearctic species because of the unusually long wings in combination with very short metasoma and the slender 3-segmented antennal clava. The length of the wings may be interpreted as a correlation with the high altitude adaptive trends discussed in the introduction. The Latin name suggests the high altitude habitat of this species. scutellum finely and evenly coriaceous-punctate; notauli dilated in posterior half, not crenulate at bottom; fore wing reaching to tip of metasoma; basal vein pale.
Metasoma only slightly longer than head and mesosoma combined (75:70), distinctly humped at junction of T1 and T2; T1 with only minute costae along anterior margin, otherwise smooth and glabrous, with tufts of hairs at sides; T2 with minute costae as in T I , otherwise smooth, with no microsculpture (160x), glabrous, except for a few scattered hairs at sides; anterolateral foveae on T2 small and not striate; T2 distinctly longer than T3-T6 combined (42:28), longer than wide (42:37); T3-T6 almost smooth, with one row of hairs each; T6 wider than long (17:lO); S6 shorter than S3-S5 combined (15:17) REMARKS. The female of this species is distinctive in combining a humped base of the metasoma with a relatively short S6. The rather abrupt 3-segmented clava and fine coriaceous sculpture of the head are also diagnostic. The species is named in honour of Miss Ann Konecny who donated a small collection of microhymenoptera to the CNC. The original description is rather laconic, incomplete, and in some respects incorrect. This redescription is based on the unique holotype.

Metaclisis carinata
Male. Length 1.2 mm. The original description states that the body is "black, legs brownish yellow, the femora and tibiae embrowned, the coxae black, tegulae piceous-black, wings subhyaline, the submarginal vein brown ..."; the present colour of the body is light chestnut brown, with legs and antennae yellowish brown, with wings slightly infuscate (the type is some 88 years old).
DISTRIBUTION. Washington, D .C. BIOLOGY. Unknown. REMARKS. Only the holotype is known. Although sexed correctly by Ashmead as a male (on det. label) it was eventually described as a female. The short scape (shorter than interorbital space) as well as the highly arched mesosoma makes the male of M. carinata quite distinct. It could be compared with the male of M.
vernalis; however, it differs from the latter by the shorter scape. There is a remote possibility that the male of M. carinata is an opposite sex to one of the new species described in this paper and based only on the female.