一种危害鹅掌楸的新叶蜂

A New Species of the Genus Megabeleses from China (Hymenoptera, Tenthredinidae)

In the present paper a new species of sawflies from China is described, which is an important destructive forest insect pest of Liriod-endron chinense (Hemsl.) Sarg. The type specimens are kept in the collection of forest insects in the Research Institute of Forestry, CAF. Megabeleses liriodendrovbrax n. sp.Female: Robust; head black, shing; palpi brownish black; antennae black. Thorax black, shining; cenchri brownish black; wing hyaline, apex slightly infuscated; vein and stigma black; legs black; front and middle tibiae and tarsi whitish brown; back of coxae and first trochanters of hind leg with white spots. Abdomen black with bluish lustre; most of lateral sides of abdominal tergum white; sawsheath black. Anterior margin of clypeus slightly emarginate; middle fovea round, deep; frontal carina and antennal furrows well defined; postocellar area convex; coronal sutures and lateral sutures distinct; OOL:POL:OCL = 2.951:1.4; length of postocellar area:width = 1.3:1. Body length 10~11 mm. Antennae with 9 segments; length of third antennal segment: total length of fourth and fifth antennal segments = 1:1.7, Punctures of head fine and dense; clypeus and frontal ridges rugosely punctate; punctures of thoracic nota fine and moderately dense; thoracic pleura with coarse and dense punctures forming reticulate pattern; punctures of first abdominal tergum coarse and dense; remaining terga with rather fine and sparse punctures. Sawsheath projecting beyond abdominal apex and apex of saw projecting beyond sawsheath; lancet as in fig. 2. Body with pale yellowish pubescence; wing membrane with numerous black short hairs.Male: Hairs of antennae much longer; hind coxae and first trochanters of hind leg and most of lateral sides of first abdominal tergum white. Punctures of head, thorax, and abdomen rather coarse and dense; OOL:POL :OCL = 2.9:1:2.4; length of postocellar area:width = 1.4:1. Body length 9~ 10mm; length of third antennal segments:length of fourth plus fifth antennal segments = 1:1.9. Subgenital plate round (fig. 3). Penis valve as in fig. 4. Remainder of coloration and structure as in female.Variability: Individual female specimen with white spots on the back of hind tibiae; individual male specimen with white spots on back of hind coxae and on first trochanters of hind legs.Host plant: Liriodendron chinense (Hemsl..) Sarg.Holotype ; Tonggu County, Jiangxi Province; May 1,1988; Ou Yang Guiming, Yang Xiaoping leg. Allotype; same data as for holotype. Paratypes 4, 4 ; same data as for holotype.The new species is closely allied to Megabeleses crassitarsis Takeuchi, but differs from the latter in the following characters: posttergite black; cenchri brownish black; base of hind femora black; lateral sides of first abdominal tergum with white parts; mesoscutellum of the female without longitudinal median carina; male abdomen longer than the head and thorax.