Redescription of Archaeoscelio Brues and Description of Three New Genera of Scelionidae (Hymenoptera): A Challenge to the Definition of the Family

Abstract Four genera—Archaeoscelio Brues; Cobaloscelio Johnson and Masner, new genus; Plaumannion Masner and Johnson, new genus; and Huddlestonium Polaszek and Johnson, new genus—lack laterotergites and laterosternites in the metasoma, one of the synapomorphies of the superfamily Platygastroidea. The Baltic amber species Archaeoscelio rugosus Brues and Archaeoscelio filicornis Brues are diagnosed and figured, and two species from Baltic amber are described in Cobaloscelio—C. cuspidatus Johnson and Masner, new species and C. speculifer Johnson and Masner, new species. Plaumannion fritzi Masner and Johnson, new species Brazil and Plaumannion yepezi García, new species Venezuela are described. Huddlestonium exu Polaszek and Johnson, new species is described from São Tomé and the Ivory Coast. The wing venation of Scelionidae is reinterpreted, and the marginal vein of Scelionidae and Chalcidoidea is considered to be a convergent feature.


INTRODUCTION
The superfamily Platygastroidea is a common and widespread group of parasitic Hymenoptera comprising 240 valid genera and 4666 species. The group traditionally was classified within the portmanteau concept of Proctotrupoidea, but support for its separate recognition has grown (for example, Masner in Goulet and Huber, 1993;Naumann, 1991). The monophyly of the Platygastroidea was first proposed by Masner (Goulet and Huber, 1993). The current evidence supporting this hypothesis comes primarily from two character systems: the modified structure of the abdomen in relation to function of the ovipositor, and the unique sensilla of the female antenna (Austin et al., 2005).
Two families are currently recognized: Scelionidae and Platygastridae. All scelionids are egg parasitoids of insects and spiders, attacking insects in the orders Orthoptera, Mantodea, Embiidina, Odonata, Hemiptera, Neuroptera, Coleoptera, Diptera, and Lepidoptera. Platygastrids are primarily larval or egg-larval parasitoids of Cecidomyiidae (Diptera), but also are known as egg parasitoids of Coleoptera and Hemiptera and nymphal parasitoids of sternorrhynchous Hemiptera. No known synapomorphies define the family Scelionidae (Masner and Huggert, 1989).
Platygastrids are generally distinguished from scelionids by the smaller number of antennomeres (7-10) and their reduced wing venation (Goulet and Huber, 1993). The forewing has, at most, a single tubular vein (e.g., fig. 41), the submarginal vein (R), and perhaps most species have no wing venation at all. Scelionids, in contrast, generally have 11 or 12 antennomeres, although a number of genera, including some common and speciose groups, have fewer. The wing venation is usually somewhat more elaborate, typically consisting of the submarginal (R), marginal (C+R), stigmal (r-rs), and postmarginal veins (R 1 ) (figs. 42-47, venational homology following Goulet and Huber, 1993).
This view of scelionid relationships is very linear, dominated by the trend toward reduction in character states. This picture is disrupted by the four taxa that are the subject of this paper. Two genera, Archaeoscelio and Huddlestonium, n. gen., have more than 12 antennomeres, yet they have a tibial spur formula of 1-1-1. All four genera share modifications of the metasoma that distinguish them from all other platygastroids: (1) a deep, basally compressed S1 and S2; (2) the anterior protrusion of S2 between the hindcoxae; and (3) a fundamentally different articulation between terga and sterna in which both laterotergites and laterosternites are missing. The forewing venation also requires a different interpretation of groundplan character states and homology. Whether these character states should be considered as synapomorphies is a question that we cannot yet answer. We defer this to a comprehensive analysis of platygastroid relationships.
The authorship accorded to the new taxonomic names proposed herein varies because of the independent work involved. Dr. José Luis García (MIZA, Venezuela) is credited with the description of Plaumannion yepezi; in addition, he collected the only known specimen. The characters used in the descriptions also vary somewhat because of the small number of specimens available and the difficulty in observing some features in the fossils.
RELATIONSHIPS: Archaeoscelio generally has not been included in discussions of scelionid relationships, except to note that the 14-segmented antennae are a plesiomorphic feature. In his original description, Brues (1940) expressed doubts as to whether Archaeoscelio was correctly placed within the Scelionidae. He noted a similarity in habitus and the structure of the mandibles with Chalcidoidea, but stated that ''the wing venation is not in close conformity with that of any group known to me'' (Brues, 1940: 90). The similarity in the mouthparts is, presumably, the fact that the mandibles are large, fairly robust, and bear sharply pointed apical teeth. However, the number and shape of mandibular teeth are extremely variable in both superfamilies, and these characters are commonly used to distinguish among closely related species.
ETYMOLOGY: Constructed from scelio, Latin for scoundrel, and a common base for many generic names in this group; and kobalos, a Greek word of similar meaning. The name is to be considered masculine.
REMARKS: This genus has some characters reminiscent of Platygastridae, particularly in the shape of the mesopleural scrobe, the shape of the notauli, and the clavate femora. The apex of the radicle inserts into the base and is parallel to the long axis of the scape. This orientation suggests that, despite the similarity in the anterior projection of the mesepisternum and first metasomatic sternite, these two species may not be particularly closely related to the other three genera. However, Cobaloscelio shares with Archaeoscelio the extension of the mesepisternum and the base of the metasoma anteriorly between the forecoxae and hindcoxae, respectively. frons and vertex with coarse to moderately fine polygonal rugulosities; lateral ocellus distinctly remote from eye margin, OOL subequal to slightly longer than LOL, shorter than POL; frons strongly convex, without antennal scrobe, median carina absent; interantennal process not developed; submedial carina absent; orbital carina absent; malar region without fanlike striae; eye glabrous, small; interocular space broad, distinctly greater than eye height; inner orbits parallel to subparallel, not diverging ventrally; torulus contiguous with upper margin of clypeus, opening ventrally, with dorsal rim produced and overhanging antennal articulation; clypeus small, convex, finely setose, without protruding anterolateral corners, anterior margin convex anteclypeus and postclypeus subequal in height, distinguished by change in orientation; malar sulcus absent; malar region and gena shallowly concave for reception of antennal scape (figs. 33, 34); mandibles massive, scissorlike, bidentate; mandibular teeth arrayed vertically, acute, deeply incised, right mandible with lower tooth distinctly longer than upper, left mandible with teeth subequal in length; maxillary palpus ( fig. 27) long, fivesegmented, segment 3 medially lobate; labial palpus two-segmented; female antenna with 12 antennomeres; longitudinal axes of radicle and scape nearly perpendicular to one another ( fig. 27); scape cylindrical, widest apically, apex excavate for reception of pedicel and base of flagellum; A3 of female elongate, slightly longer than A2; female antenna with nonabrupt clava composed of seven modified antennomeres, with appressed, white setae on dorsal surface; claval formula A12-A7 2-2-2-2-2- 1. Mesosoma (figs. 25,26,31,32) short, squat, about as high as wide, viewed from above nearly quadrate; pronotum, in dorsal view, abruptly truncate anteriorly, anterolateral corners sharply angulate, protruding anteriorly in P. yepezi; transverse pronotal carina present; pronotal humeral carina present; dorsal surface of pronotum finely to coarsely areolate; anterior surface of pronotum nearly vertical, abruptly sloping down to cervical region; lateral surface of pronotum deeply concave ( fig. 31), finely sculptured; epomial carina present, acute, extending ventrally to forecoxa; netrion/epicnemium linear; pronotal-mesoscutal suture straight or slightly concave laterally (figs. 26, 32), exposing large dorsal surface of pronotal humeri; anterior margin of mesoscutum meeting pronotum dorsally; mesoscutum trapezoidal to subtriangular, moderately convex, anteriormost point narrowly separated from transverse pronotal carina; skaphion absent; notauli and parapsidal lines absent; mesoscutal sculpture variable, from coarsely to finely areolate; transscutal articulation very broad, deep; scutellum relatively large, subtriangular, areolate-rugose, posteromedially produced into massive, pointed spine, anterior margin with broad, regularly spaced deep lacunae; axilla not clearly defined; metanotum narrow, dorsellum Figs. 25 unarmed, not projecting, delimited by fine transverse arched line; propodeum with dorsal face extremely narrow medially, shorter than length of dorsellum, rugulose, posterior face above foramen smooth, glabrous; mesopleuron relatively narrow, mesepisternum and mesepimeron not differentiated by suture or line of foveae; mesopleural depression shallow; mesopleural pit absent; mesopleural carina obscured by coarse polygonal sculpture; upper mesepisternum longitudinally carinate; sternaulus not developed; anterior margin of ventral portion of mesepisternum moderately to strongly extended anteriorly between forecoxae; posterodorsal corner of mesopleuron rounded; mesopleuron and metapleuron separated by distinct suture (fig. 31); metapleuron very large, posterior margin weakly concave, with narrow band of dense setae along posterior margin; metapleural pit absent; upper angles of posterior margin of metapleuron weakly produced; propodeum with anterodorsal face densely setose; posterolateral corners of propodeum very strongly developed and projecting; legs robust; posterior face of hindcoxa smooth; trochantellus present on all legs; femora moderately to distinctly incrassate, apices with lateral lamellae flanking base of tibiae; tibial spur formula 1-1-1; tarsi 5-5-5, tarsomeres gradually tapering in width toward apex; pretarsal claws small, simple; forewing ( fig. 28)  costal margin, width of cell gradually expanding apically; no bulla in R basad of apical fork; R 1 very short, not reaching wing margin as tubular vein; r-rs longer but ending blindly as tubular vein; Rs extending beyond apical fork as arched nebulous vein to costal margin; first free segment of M (basal vein) not indicated; hindwing broad, with posterior margin strongly sinuate, marginal cilia very short; R tubular, basally remote from costal margin, apically gradually fusing with margin, without distinct angle, marginal vein short; with three hamuli at wing margin.

KEY TO SPECIES OF COBALOSCELIO
Metasoma (figs. 26, 29, 30, 31) short and robust, broadly sessile, laterally without sharp edge or submarginal groove; female with six visible terga, five sterna; laterotergites and laterosternites apparently absent; terga nearly flat; sterna strongly convex; lateral margins of terga slightly overlapping over upper margins of sterna; terga 1-4 with strongly raised sublateral keels, coarsely sculptured; basal margins of terga and sterna without distinguishable crenulae; T1 moderately to distinctly largest tergite, longer than T2, with very sharp, raised anterior transverse carina; T2 transverse, coarsely areolate rugose; T6 medially with oval, flat, raised field covered with silvery surface, either microtrichiae or a secretion, laterally with two densely pilose fields; tip of cercus visible protruding beyond apex of T6, with two long, apical whitish bristles; T7 diminished, concealed under T6, apparently not extruded with ovipositor; internal details of T7, T8 not examined; S1 (fig. 29) very deep, strongly convex, with zone of dense pilosity on posteromedian margin, anteromedial portion with sharp median keel extending anteriorly between hindcoxa, coxae fitting into basal depressions in sternite; anterior margin of S2 straight; metasomatic felt fields absent; S5 not observed; visible portion of ovipositor robust, internal structure not observed, apices of gonoplacs rounded, setose; details of ovipositor structure and related metasomatic apodemes not observed.
DIAGNOSIS: The genus Plaumannion may be distinguished from Archaeoscelio by the 12merous antennae and the arrangement of the mandibular teeth along the length of the mandible (as in many ants). The genus may be separated from Huddlestonium, n. gen. by the 12-merous antennae and the single, medial protrusion of the scutellum into a spine.
ETYMOLOGY: Named in memory of Mr. Fritz Plaumann, distinguished German naturalist and philosopher, formerly of Nova Teutonia, Brazil. Plaumann contributed tremendously toward the knowledge of Brazilian insects and spiders by collecting, over the decades, many species, including the type species of this genus. The gender of this name is to be considered neuter.
REMARKS: The genus Plaumannion fits nowhere within any of the variations on classification of Platygastroidea. The protruding scutellum, forewing venation, and lack of a malar sulcus are characters commonly encountered in Platygastridae, but are rare or absent in scelionids. Conversely, the 12merous antennae have never been found in either extant or fossil platygastrids. In the key of Masner (1976), Plaumannion will match up to couplet 20, at which point the key fails. The couplet distinguishes between genera in which either T2 is the longest metasomatic tergite, or those in which T2 and T3 are subequal in length and longer than any other. In this new genus, T1 is the longest tergite, thus distinguishing it from almost all previously known scelionids. One apparent exception is females of the genus Baeus in which the true first metasomatic segment is reduced in size and largely hidden. Plaumannion may be distinguished by the presence of wings (female Baeus are micropterous) and by the segmented antennal clava of the female (female Baeus have the apical antennomeres fused).
Plaumannion is the ''Genus P'' used as an outgroup in the phylogenetic analysis of relationships among species of Nixonia (Johnson and Masner, 2006 . 27); malar space above mandible with triangular smooth area; pronotum, seen from above, with anterior margin on each side slightly convex, anterolateral corners weakly projecting ( DIAGNOSIS: Distinguished from Plaumannion yepezi, n.sp. by the coarse sculpture of the head and mesosoma, the dense setation of the posterior metapleuron and lateral face of the propodeum, and the strongly developed submedian carinae on T1.
ETYMOLOGY: Named in honor of its collector, Mr. Fritz Plaumann.
MATERIAL EXAMINED: Holotype female: BRAZIL: Santa Catarina, Nova Teutonia, 27u119S 52u239W, 300-500 m, X- XI.1972, Fritz Plaumann; OSUC 146569. Deposited in CNCI. Paratype: 1 female, with same data as holotype, OSUC 146570 (CNCI). After this paper was initially submitted for publication, a third specimen was found, a headless female, also from Nova Teutonia, 30. XII.1944, F. Plaumann, B.M. 1957 #790387. Because of its severely damaged condition, we have not designated it as a paratype. REMARKS: Plaumann (in litt.) noted that the two type specimens were collected by sifting soil litter. The area of Nova Teutonia, although located far inland, was originally covered by the Brazilian Atlantic rainforest. As a consequence of a half millennium of settlement and agriculture, the forest is now greatly reduced in area and highly dissected (see, for example, Galindo-Leal and Câ mara, 2003). The scientific community, in collaboration with Brazilian entomologists, should make a focused effort to document the arthropod fauna of this threatened environment. Even with such an effort, however, creatures such as P. fritzi will not be encountered often. In over three decades of collecting at sites in and around the town of Nova Teutonia, Plaumann succeeded in capturing only three female specimens.
DIAGNOSIS: Distinguished from P. fritzi by the finer, nonmatte body sculpture, particularly on the head, the more restricted distri-bution of fine hairs on the metapleuron and lateral propodeum, T1 distinctly longer than T2, and the lack of submedian carinae on the basal metasomatic tergite.
ETYMOLOGY: Named in honor of Francisco Ferná ndez Yépez, a prominent Venezuelan entomologist.
REMARKS: The only known specimen of this species was collected in a cacao plantation. The tremendous distance between this collecting locality and that of the only other known species of the genus, together with the numerous morphological features that distinguish the two, suggests to us that we may well discover further new species of Plaumannion in South America. If so, they must be decidedly rare. After the initial collection of P. yepezi, numerous efforts to capture additional specimens were unsuccessful. DESCRIPTION: Length: 0.8 mm. Body compact, head and metasoma closely appressed to mesosoma. Head lenticular, convex anteriorly, nearly flat posteriorly, strongly transverse; hyperoccipital carina absent; occipital carina complete medially; vertex and upper portion of frons lacking coarse surface sculpture, with distinctly separated, shallow umbilicate punctures, these superimposed on shallowly reticulate microsculpture (Sã o Tomé), or microsculpture entirely absent (Ivory Coast); lateral ocellus distinctly remote from eye margin, OOL subequal to slightly longer than LOL, shorter than POL; frons strongly convex, without antennal scrobe, weak median carina present, bifurcating above interantennal process and passing on either side of toruli, extending dorsally one-third distance to median ocellus; interantennal process weakly raised, relatively broad, width subequal to diameter of torulus; submedial carinae absent; orbital carina on frons present, extending from anterior mandibular articulation dorsally to merge with inner orbit; area between orbital carina and malar sulcus smooth, without fanlike striae; eye glabrous, small; interocular space broad, distinctly greater than eye height; inner orbits parallel to subparallel, not diverging ventrally; torulus contiguous with upper margin of clypeus, frons curved so that toruli open facing ventrally, dorsal rim slightly overhanging antennal articulation; clypeus small, flat, setose, without protruding anterolateral corners, anterior margin pointed medially, with median longitudinal carina that continues dorsally from point to merge with interantennal process; differentiation into anteclypeus and postclypeus not apparent; malar sulcus present; gena with oblique carina arising from near anterior mandibular articulation, extending posteriorly to merge with occipital carina, anterior to this oblique carina surface depressed, possibly serving as depression for antennal scrobe; mandibles massive, scissorlike, tridentate; mandibular teeth arrayed vertically, acute, deeply incised, right mandible with lower tooth distinctly longer than upper teeth, left mandible with teeth subequal in length; maxillary palpus long, four-segmented, segments 2 and 3 medially expanded into weak lobe; labial palpus two-segmented; female antenna with 13 antennomeres ( fig. 38); longitudinal axes of radicle and scape nearly perpendicular to one another; basal half of scape cylindrical, narrow, apical half flattened anteroposteriorly, distinctly expanded; A3 of female not distinctly elongate, shorter than A2; female antenna with nonabrupt clava composed of seven antennomeres, with appressed, white setae on dorsal surface; claval formula 1-2-2-2-2- 1. Mesosoma (figs. 35,36) short, squat, about as high as wide, viewed from above nearly quadrate; pronotum, in dorsal view, abruptly truncate anteriorly, anterolateral corners strongly angled but not protruding; transverse pronotal carina present; pronotal humeral carina present; dorsal surface of pronotum coarsely areolate-rugose; anterior face of prothorax nearly vertical; lateral surface of pronotum concave, with weakly developed longitudinal carinae; epomial carina strongly developed and acute, extending down to forecoxa; netrion/epicnemium linear; prono-tal-mesoscutal suture concave laterally, exposing large dorsal surface of pronotal humeri; anterior margin of mesoscutum meeting pronotum dorsally; mesoscutum trapezoidal n.sp. 35, Holotype female, lateral habitus (OSUC 148692). 36, Paratype female, dorsal habitus (OSUC 148693). 37, Holotype female, head, frontal view. 38,Antenna,lateral view. 39,Wings. 40,Ovipositor,lateral (top) and ventral view (bottom). gp, gonoplacs. Scale bars in millimeters.
to subtriangular, moderately convex, anteriormost point contiguous with transverse pronotal carina; skaphion absent; notauli and parapsidal lines absent; anterior half of mesoscutum with umbilicate setigerous punctures, density of punctures decreasing posteriorly, posterior half of sclerite with few scattered umbilicate punctures sublaterally, otherwise shallow reticulate to smooth; transscutal articulation broad, deep; scutellum very large, subtriangular, coarsely areolate-rugose, posterior margin produced into pair of submedial rounded points, anterior margin with broad, regularly spaced deep lacunae; axilla clearly developed; metanotum narrow, dorsellum unarmed, not projecting, delimited by fine transverse carina; propodeum not visible dorsally, posterior surface glabrous, vertical, foramen transversely oval, opening between hindcoxal cavities; mesopleuron relatively narrow, mesepisternum and mesepimeron not differentiated by suture; mesopleural depression shallow; mesopleural pit absent; mesopleural carina indicated by arched line of coarse punctures; upper mesepisternum smooth; sternaulus not developed; anterior margin of ventral portion of mesepisternum moderately extended anteriorly between forecoxae; posterodorsal corner of mesopleuron rounded; mesopleuron and metapleuron separated by distinct suture (fig. 35); metapleuron large, rectangular, posterior margin weakly concave, setose throughout, setae denser in posterior dorsal half; metapleural pit absent; upper angles of posterior margin of metapleuron weakly produced; propodeum with anterodorsal face setose; posterolateral corners of propodeum distinctly projecting posteriorly; legs slender; posterior face of hindcoxa smooth; trochantellus present on all legs; all femora slightly to moderately incrassate, apices with lacking distinct lateral lamellae; tibial spur formula 1-1-1; tarsi 5-5-5, tarsomeres gradually tapering in width toward apex; pretarsal claws small, simple; forewing broad ( fig. 39), with marginal cilia short; R (submarginal vein) tracheate, pigmented, rather short, not extending beyond basal 0.4 of wing, broadly remote from costal margin, width of cell gradually expanding apically; no bulla in R basad of apical fork; R 1 very short, not reaching wing margin as tubular vein; r-rs longer but ending blindly as tubular vein; Rs extending beyond apical fork as arched nebulous vein to costal margin; first free segment of M (basal vein) present as nebulous vein, inclined with lower end farther apicad than upper end arising from R; hindwing broad, posterior margin strongly sinuate, marginal cilia short; R tubular, basally remote from costal margin, apically gradually fusing with margin, without distinct angle, marginal vein short; with three hamuli at wing margin. Metasoma (figs. 35,36) unusually short and robust, broadly sessile, laterally without sharp edge or submarginal groove; female with six visible terga, five sterna; laterotergites and laterosternites absent; terga nearly flat; sterna strongly convex; lateral margins of terga slightly overlapping over upper margins of sterna; terga 1-4 without sublateral keels, coarsely sculptured; basal margins of terga and sterna crenulate; T1 narrow, striplike, longitudinally costate; T2 strongly transverse, but longer than T1 or T3, basally costate, sculpture becoming areolate-rugose laterally; T6 medially with oval, flat, raised field covered with silvery surface, either microtrichiae or a secretion, laterally with two densely pilose fields; T7 diminished, concealed within metasoma, apparently not extruded with ovipositor, lateral apodemes very short, length 0.10 times length of ovipositor, free in body cavity, length of proximal arms 0.42 times length of ovipositor; cercus short, articulated, truncate, with one pair of long setae and one short seta; T8 not differentiated; S1 very deep, strongly convex, anteromedial portion with sharp median keel extending anteriorly between hindcoxa, coxae fitting into basal depressions in sternite; anterior margin of S2 straight; metasomatic felt fields on S2 absent; apical sternite (S5) without median apodeme; ovipositor ( fig. 40)  The most current key for the identification of world genera of Scelionidae (Masner, 1976) begins by separating the three subfamilies. The genera treated here clearly do not belong to either the Teleasinae or Telenominae, but they do not match the characters used to distinguish the Scelioninae. Nevertheless, if one tries to identify the two extant genera Plaumannion and Huddlestonium, the key fails at couplet 60 in which the relative length of the stigmal vein is evaluated. Neither genus has a classical stigmal vein and so fits neither half of the couplet. The key may be modified as follows to accommodate these two new genera: 60 The following key may be used to distinguish the taxa treated in this paper, all of which have the mesepisternum produced anteriorly between the forecoxae, S1 produced anteriorly between the hindcoxae, and, depending on one's perspective, either lack laterotergites or have a different mechanism locking together metasomatic terga and sterna. This short key mixes fossil and extant taxa and is presented as a means of summarizing the diagnoses for each.

DISCUSSION
It is tempting to ascribe some biogeographic significance to the apparently complementary distributions of Huddlestonium and Plaumannion in Africa and South America, respectively. The superfamily Platygastroidea is well represented in fossils from the mid-Cretaceous (Grimaldi et al., 2002), predating the final physical separation of those two continents. Among other scelionids, Chromoteleia Ashmead is found in the Neotropics as well as West Africa. In addition, a few living taxa, with relatively good numbers of collections, exhibit transantarctic distributions, for example, Archaeoteleia Masner (Chile and New Zealand) and Proplatygaster Kieffer (Chile and Australia). The two extant genera treated here may yet be another case to add to this list, but the level of ignorance concerning their real geographic distributions mandates that this should be done only with extreme caution.
Even less information is available concerning host relationships. Plaumannion fritzi was collected by sifting litter; the series of Huddlestonium exu from Sã o Tomé was captured in a Malaise trap in grassland with tall shrubs. The robust body of the adult wasps suggests that the host, presumably an egg, is probably a prolate spheroid in shape. The short, Ceratobaeus-type ovipositor implies that the parasitoid is capable of coming in close contact with the egg.
When we first began studying this group of genera, one troubling issue was how the reduced venation could be reconciled with that found in other members of the family. In the typical interpretation of the tubular veins of scelionids (figs. 41-47) and chalcidoids ( fig. 48), there is a more or less elongate submarginal vein (figs. 41-47, R, venational homologies from Goulet andHuber, 1993, Sharkey andRoy, 2002;fig. 48, sm) that curves toward the costal margin apically. As the vein meets and then runs toward the apex along this margin it is referred to as the marginal vein ( One problem with this interpretation is that there are a number of scelionids (figs. 43, 45, 46, 47) in which the stigmal vein arises from the submarginal vein and not the marginal; that is, r-rs arises basad of any possible fusion of R with C. In such a case, the marginal vein is absent or ''punctiform' ' (fig. 47). We suggest that platygastroid wing venation may be better understood and homologized by comparison with the wings of Cynipoidea, in particular, with the wings of Liopteridae ( fig. 49, Ronquist 1995: fig. 39). Such a comparison may be useful only in that cynipoids may retain some plesiomorphic characteristics in the layout of their wing venation. We are not asserting that Platygastroidea and Cynipoidea are sister groups. The relationships of platygastroids with other Apocrita are not at all resolved, and the true sister group may be any one or a combination of several other groups (see summary in Austin et al., 2005).
We hypothesize that in the platygastroid groundplan, the stigmal vein (r-rs) arises from R 1 before the latter reaches the costal margin of the wing. Such a condition is found in all Platygastridae in which veins are present, as well as most of the putatively basal clades in Scelionidae, viz.,Nixoniini (fig. 42), Sparasionini ( fig. 43), Scelionini (fig. 45), and some Baryconini (figs. 46,47). The illustration of the wing venation in the sparasionine genus Archaeoteleia in Dangerfield et al. (2001: fig. 5.18) shows that what appears to be a marginal vein is in fact merely pigmentation between the apex of the submarginal vein and the costal wing margin. Neuroscelio, however, has a well-developed marginal vein ( fig. 44; fig. 5.21 in Dangerfield et al., 2001). In other groups (e.g., many Baeini), the stigmal vein arises at the point where R 1 reaches the costal margin and there is no marginal vein per se. The published illustrations of the venation in the fossil species Brachyscelio cephalotes Brues (Brues, 1940;Dangerfield et al., 2001) are misleading. We have reexamined the holotype of this species upon which these illustrations are based. The depiction of R 1 as distant from the costal margin is an artifact of preservation: the wing is surrounded by a slightly larger pocket, of exactly the same shape, as if the wing shrunk away after the amber hardened around it. Thus, the wing venation, clearly visible because of its darker color, appears to be distinctly separated from the apparent costal margin. In fact, R 1 runs along the costal margin of the wing in a completely normal manner.
If the plesiomorphic condition is that r-rs branches from R behind the costal margin, then there seems to be no reason to postulate that C is involved in the formation of the marginal vein. Rather, it would be entirely composed of R 1 , and this is the homology used in Dangerfield et al. (2001). It appears to us that the development of a marginal vein occurred as an event within the family Scelionidae, perhaps on more than one occa-sion. Thus, if a marginal vein is present in the groundplan of Chalcidoidea, this feature would not be homologous with the similar vein in Platygastroidea.
The family Scelionidae is generally recognized by the possession of a so-called ''submarginal ridge'', a feature formed by the narrow interlocking laterotergites and laterosternites. This is characteristic of most Scelioninae and all Teleasinae. However, many species, for example, in the Telenominae, Aradophagini, some Thoronini, and some Baeini, have a somewhat different structure, with broad laterotergites that exten- sively overlap the sterna beneath; telenomines, moreover, lack laterosternites. In the four genera described in this paper an entirely different metasomatic structure is found: the terga and sterna abut closely and tightly, but no subdivisions are found. The terga and sterna do not appear to be fused, as demonstrated by dissections of Huddlestonium and the postmortem inflation of the metasoma in some specimens of Archaeoscelio (e.g., fig. 1).
These results suggest that we should reconsider the characters that have been used to define the family Scelionidae. Austin and Field (1997) have already suggested that Sparasionini and Platygastridae form a monophyletic, basal branch of the platygastroid phylogeny. Our results are consistent with the hypothesis that the family Scelionidae is not monophyletic, but they do not resolve the questions that flow from that proposition. We could reasonably argue that the four genera discussed here should be recognized as a new higher taxon, at least at the tribal level and perhaps even representing a new family. To do so, however, begs the question of defining other monophyletic groups within the superfamily and documenting their relationships. A formal reclassification requires a broadly based phylogenetic analysis, a goal toward which we are presently working.

ACKNOWLEDGMENTS
Thanks to the curators of the collections cited for the opportunity to study the material under their care; to J.L. García, for his discovery and recognition of Plaumannion yepezi; to L. Musetti (Columbus, Ohio) for editorial, curatorial, and database support; to K. Bolte for assistance with figures; and to J.-W. Janzen (Seevetal, Germany) for sparking interest in the Baltic amber specimens. We express our appreciation, as well, for the input of the reviewers of this manuscript. This material is based on work supported in part by the National Science Foundation under grant No. DEB-0344034.