THE GENUS OETHECOCTONUS ASHMEAD IN NORTH AMERICA (HYMENOPTERA: PROCTOTRUPOIDEA: SCELIONIDAE)

Abstract The genus Oethecoctonus of North America is revised. Three species are recognized, of which two are new to science: O. ophrynopus and O. pleuralis. O. oecanthi (Riley), the type-species of the genus, is redescribed and figured. A generic diagnosis of Oethecoctonus and key to North American species are given. The higher classification and world distribution of Oethecoctonus species are discussed. Résumé L'ouvrage revoit le genre Oethecoctonus d'Amérique du Nord. Trois espèces sont identifiées, dont deux nouvelles, soit O. ophrynopus et O. pleuralis. O. oecanthi (Riley), l'espèce type du genre, est rédécrite et illustrée. L'auteur donne un diagnostic générique de Oethecoctonus et une clef d'identification des espèces nord-américaines. Il étudie la classification supérieure et la distribution mondiale des espèces de Oethecoctonus.


INTRODUCTION
Members of the genus Oethecoctonus, so far as known, attack the eggs of tree crickets (Orthoptera: Oecanthidae). The slender shape of the adult wasps is determined by the shape of the host eggs in which the entire postembryonic development of the parasitoid takes place. There is always only one parasitoid per egg attacked and it fills the entire inner space of the host egg when fully mature. The host eggs are laid randomly or in series, deeply embedded in the tissues of various plants. Oethecoctonus females presumably search for minute scars, indicators of oviposition, on the surface of plants. It seems that the wasps spend most if not all of their adult life around the plants. Consequently, adults of Oethecoctonus are very seldom caught by sweeping and never encountered in pan or pitfall traps. Malaise traps, particularly in the tropics, seem to be more productive. However, a beating sheet (with special sleeve-like attachment) is possibly the best collecting technique, particularly for night collecting on bushes. Adults of Oethecoctonus are assumed to be crepuscular and nocturnal in habits, as are their hosts, the tree crickets. This assumption is based on generally large ocelli in adults of most species; individuals of some undescribed Neotropical species of Oethecoctonus (in CNC) exhibit extremely large ocelli. Similarly, it is interesting to note that adults are sometimes caught in light traps.
Oethecoctonus is a pantropical genus, with only a few species penetrating the temperate zones (Masner 1976). No species is at present known from the Palearctic region and only three species are reported here from North America. The Neotropical region (excluding Chile) is particularly rich in species; 20 undescribed species were recognized in the large amount of Neotropical material in the CNC alone. Interestingly enough, only two species have been described from the Neotropical region, viz., 0. insularis (Ashmead) and 0. laticinctus (Ashmead), both from St. Vincent, W.I. Masner (1976) classified Oethecoctonus in the tribe Calliscelionini and compared it with Probaryconus Kieffer. These two genera seem to intergrade, particularly in the Neotropical region. Solution of this problem is deferred to a later date when more accumulated material should permit proper interpretation of generic limits. At present the two genera are interpreted and distinguished upon character states used by Masner (1976Masner ( , 1980. No attempt is made at this time to define species-groups in Oethecoctonus. However, the three species in North America appear to be closely related to one another, and represent an extension of a Neotropical group which includes the Caribbean 0. insularis. Some Neotropical species are characterized by the peculiar regional colour pattern in which the head and metasoma are melanic whereas the mesosoma is bright red. All specimens were mounted on points. To study the microsculpture (e.g. fine shagreening on mesoscutum) and to avoid glare and light reflections at high magnification (160 x ) a sheet of tracing paper (Mylar) was placed between the source of light and the specimen. For the best results the specimen should be as close to the above light disperser as safely possible. Slender, elongate forms; head in dorsal view subquadrate; mandibles short, tridentate; clypeus rectangular, rather narrow, not wider than outside rims of toruli, with anterolateral comers pointed but not prominent; palpal formula 4-2; frontal despression not developed, lower frons bisected by a median keel ascending from antennal insertion; cheeks with distinct fans of striae radiating from mandibular base; vertex rounded into occiput as horizontal part of occipital carina not developed; vertical part of occipital carina strong and sharp; ocellar triangle rather high, POL > LOL, posterior ocelli almost contiguous with inner orbits; eyes distinctly hairy; radicle short; antennal formula 12-12, female antenna with A3 longer than A2, and with distinct 6-segmented clava; male antenna with A3-A12 distinctly elongate, covered with very short hairs, A5 (sex segment) with weak carina basally.

Oethecoctonus
Mesosoma cylindrical, elongate, about as high as wide; epomial carina in dorsal view prominent and sharp; notauli and skaphion absent; netrion well differentiated, distinclty open above fore coxa; scutellum in front with row of foveolae; mesopleuron between fore and middle coxae very long; acetabular carina sharp and entire; mesopleural carina not developed or obscured by sculpturing; mesopleural depression rather shallow, mesepimeron in front with row of feveolae; metanotum narrow, not expanded, unarmed; propodeum dorsally not excavate, with two subparallel keels terminating dorsally in pair of protuberances or points; fore wing venal formula mg < st < pm, submarginal vein setose, not "broken" before merging into marginal vein, basal and medial veins at most indicated as traces; hind wing with complete submarginal vein; legs slender, tibia1 spur formula 1-1 -1, tarsal formula 5-5-5.
Metasoma elongate, moderately pedunculate, with T1 and T2 longitudinally costate; in female with 6 visible tergites and 6 sternites, with T1 distinctly elongate, without hump, with T2 almost as long as T3, the latter the widest, with T6 wider than long, with T7 not exposed but articulating with ovipositor; in male with 8 visible tergites and 7 sternites. Oethecoctonus ophrynopus n. sp.
Mesopleuron below mesopleural depression rugoso-punctate; scutellum mostly smooth, with a few scattered punctures; propodeal keels terminating in low points in anterior half of propodeum.

Distribution. Arizona.
Variability. The female from Ramsey Canyon shows longitudinal striae on T3 more distinct than in the holotype. This kind of sculptural variation involving T3 is found also in 0 . oecanthi.
Remarks. 0. ophrynopus can be distinguished from 0. oecanthi by having strong supraorbital tori and frons between them more concave. From 0. pleuralis it differs by sculpturing of mesopleura. The name of this new species refers to its supraorbital tori ("eyebrows"), unique among the Nearctic members of Oethecoctonus.
Male. Length 2.4 mm. Dark brown to black; antennae and legs (except for darker coxae) light brown; wings clear.
Metasoma very slender; T3 with longitudinal sculpture all over, with no rugulosities or coriaceous elements at sides; T4-T6 almost smooth, with scattered setigerous punctures.
Type material. Holotype 8 (USNM), ARIZONA, Santa Rita Mts., Madera Canyon, August 9 1961, at UV light, F. Werner and J. Nutting; type well preserved. Distribution. Arizona. Remarks. The record at UV light indicates again that some members of Oethecoctonus are nocturnal. The predominantly smooth mesopleura as well as the nearly quadratic head will distinguish this species from the other two Nearctic species. There is little likelihood that 0 . pleuralis may be the opposite sex of 0 . ophrynopus, because adult sexual dimorphism of this sort is not evident in 0. oecanthi, for which both sexes are known. The name of this new species refers to the remarkable smoothness of its mesopleuron.

Oethecoctonus oecanthi (Riley)
Figs. Head subquadrate, slightly wider than long; distinct median keel (often consisting of several finer parallel keels) arising from antennal insertion and reaching to about middle of frons; frons predominantly sculptured, shagreened-punctate or rugulose-punctate, with smaller or larger smooth area around and above median keel, and with smaller smooth area immediately below are anterior ocellus, sometimes these two smooth areas confluent; cheeks above and below subocular suture with distinct fan-like striae; mandibles tridentate, FIGS 1-5. Oerhecoctonus oecanthi (Riley) 9 . 1, dorsal view; 2, lateral view; 3, head; 4, fore wing; 5, antenna. with median tooth smallest; interocellar space coriaceous, with scattered punctures; upper occiput distinctly excavated medially, coriaceous-punctate to regulose-punctate; occipital carina well developed at sides, absent at meson; supraorbital tori not developed; A3 3 . M . 3 times as long as wide, from as long as to 1.5 times longer than A2; A4 1.7-2.7 times as long as wide, from shorter than to as long as A2; A5 from distinctly transverse to slightly elongate. Pronotum at sides with distinct chain of foveolae subparallel to lower anterior margin (from fore coxa to epomial carina), with distinct patch of granular sculpture in posterodorsal corner (in front of spiracle); space on pronotum between granular patch and epomial carina usually smooth, rarely coriaceous or with slight longitudinal rugulae; netrion with transverse ridges; mesoscutum with dense punctation, interstices between punctures predominantly shagreened except in front of scutellum and variably at posterolateral as well as median parts of mesoscutum; scutellum deeply and densely punctured, with no shagreened microsculpture, with deep foveolae along anterior and posterior margins, in some individuals with minute point situated posteromedially; mesopleuron from rugoso-punctate to predominantly punctate; mesopleural depression partly smooth, with distinct mesopleural pit; mesepimeron smooth, separated from mesepisternum by chain of deep foveolae; propodeal points from indistinct to sharply protruding, often obscured by dense pilosity; fore wings slightly surpassing tip of metasoma; stigma1 vein 1.8-2.3 times as long as marginal vein.
Metasoma slightly longer than head and mesosoma combined; T1 always longitudinally costate; T2 usually costate as T I , often with some coriaceous sculpture in posterior part and at sides; T3 usually striate longitudinally at meson, and with rugosopunctate or coriaceous-punctate sculpturing at sides, rarely entire T3 reticulate-rugose or coriaceous, with scattered punctures, or almost smooth and with only delicate longitudinal aciculation and few scattered punctures; T4-T6 punctate, T4 in some individuals with some coriaceous sculpturing.
Male. Differing from female in secondary sexual characters: A3 3 times as long as wide, slightly longer than A4; A5-All 2.5 times as long as wide, A5 with low keel reaching slightly over basal half of the segment.