A NEW BRACONID GENUS ( HYMENOPTERA ) PARASITIZING WEBSPINNERS ( EMBIIDINA ) IN TRINIDAD BY

Early in 1984, while conducting field studies on embiid behavior in the Arima valley of northern Trinidad, the junior author observed a braconid wasp ovipositing into the silk webs of an embiid, Clothoda urichi (Saussure) [Clothodidae]. The wasp and a paralyzed embiid were collected, and another wasp was successfully reared from that host. Specimens were sent to the senior author, then stationed at the National Museum of Natural History (USNM), who determined it to be a new braconid genus. A search of the USNM collection yielded no comparable specimens; however, during a subsequent search of the Museum of Comparative Zoology (MCZ) collection a specimen of a different, but related, species was found. Shenefelt (1980) provided a comprehensive index to recorded braconid hosts, which does not include any Embiidina. Callan (1952) mentioned that he collected numerous white cocoons from embiid webs in Trinidad, and he reared a braconid from these which was identified only as "Apanteles sp." He suggested that these were parasites of lepidopterous larvae that sometimes live under the silk, not parasites of the webspinners. The establishment of this new genus as a parasite of webspinners therefore provides a totally new host order record for the family Braconidae. The morphological terminology used in this paper is mostly that of Marsh (1965, 1982) and van Achterberg (1974). Microsculpture terminology is that of Harris (1979). Taxonomic descriptions presented in this paper are solely the work of the senior author, while life history information on the parasite and its host was provided by the junior author.

Etymology: The name is masculine, derived from "sericum" (L.) meaning silk, in reference to the silk webs of the embiid host of the type-species.
Remarks" Based on patterns of body sculpturing we place Serico- bracon in the subfamily Doryctinae, where it is allied to Heterospi- lus Haliday.Some neotropical Heterospilus species are remarkably similar in sculpturing of the mesonotum, propodeum, and meta- somal tergites (e.g.Marsh 1982, figs.7-8).Sericobracon also agrees with Heterospilus in having the lower end of the first intercubitus desclerotized.Sericobracon may be distinguished from other doryctine genera by the absence of stout spines or pegs on the foretibia.
Subfamilial placement of Sericobracon is problematic in that recent authors (e.g.Marsh 1965; van Achterberg 1976, 1984) have cited stout foretibial spines or pegs as a defining character of the Doryctinae.However, according to van Achterberg (pers.comm.) the stout foretibial pegs of Doryctinae are probably related to living in wood or other hard substrates as larvae.Thus, it might be expected that a species not associated with larvae in wood has no distinct pegs (a secondary loss).Aside from the above mentioned similarities, Sericobracon agrees with the Doryctinae in several additional characters.These include: hindcoxa with an anteroventral tubercle, dorsope present, and paralysis of the host prior to egg deposition.
Most Doryctinae are parasites of wood-boring beetle larvae; however, Marsh (1982) notes that Heterospilus show an unusually wide range of host associations across three insect orders: Coleop- tera, Lepidoptera, and Hymenoptera.In nearly all cases the hosts have cryptic boring habits, usually in plant stems or branches.If Sericobracon is closely related to Heterospilus, then the host shift to Embiidina may not be so unusual.It is simply a shift to a phyloge- netically unrelated host, which occurs in the same microhabitat.
Life history: Clothoda urichi (Saussure), an abundant species in Trinidad, spins silk on vertical objects, generally trees, that support the growth of algae, the food of this embiid.They construct con- spicuous silken webs beneath which they live in groups, ranging from one mother with her offspring to 25 or more females with their young.On February 1, 1984 at the Simla Research Station in the Arima Valley, a braconid wasp was observed to penetrate embiid silk with her ovipositor.A paralyzed adult female embiid was found directly beneath the silk under the wasp.She was collected and placed in a petri dish in the laboratory.The female remained paralyzed until February 8 when the endoparasitic wasp larva killed the embiid and emerged to spin a white silken cocoon (.6 cm), within which it pupated.The adult wasp emerged from the cocoon on February 19.Distribution: Trinidad.
Etymology: The name refers to the Arima valley of Trinidad, the type-locality.
Etymology: Named for Howard Ensign Evans, eminent hymen opterist, gifted natural history writer, and collector of the holotype specimen.

ACKNOWLEDGMENTS
Special thanks to Dr. C. van Achterberg, Rijksmuseum van Natuurlijke Historic, Leiden, who examined a paratype of Serico- bracon arimaensis and provided his opinion on its phylogenetic placement.Additional thanks are due to Dr. P. M. Marsh, System- atic Entomology Laboratory, U.S. Department of Agriculture, c/o National Museum of Natural History, Washington D.C., and Dr. W. R. M. Mason, Biosystematics Research Institute, Agricul- ture Canada, Ottawa, Ontario, who reviewed the manuscript and provided their helpful comments.Field work by the junior author was supported by grants from the National Academy of Sciences, Sigma Xi, and the National Science Foundation (NSF Doctoral Dissertation Improvement Grant BSR-8312897).

SUMMARY
Sericobracon Shaw, a new doryctine braconid genus from the Neotropical region, is described and illustrated.Two new species are included in the genus: S. arimaensis and S. evansi, the type-species, S. arimaensis, was reared from Clothoda urichi (Saussure), the first record of Braconidae parasitizing Embiidina.