Abstract: In this paper, a new genus of Tenthredinidae from China is described and the type species is redescribed based on the holotype, allotype, and additional specimens collected in April 1983 in Changde Prefecture, Hunan Province. All the type specimens of the type species are deposited in the Forest Research Institute, The Chinese Academy of Forestry.Dasmithius Xiao, new genus Type species:Caliroa camelliae Zhou and Huang, 1980.Description: Antenna 9-segmented, filiform, length about 1.5x head width; Ist segment longer than broad, 2nd segment about as broad as long, 3rd segment slightly longer than 4th segment, apical 4 segments reduced in length compared to previous segments. Clypeus nearly truncate; very shallowly and broadly circularly emarginated without narrow lateral teeth (figs 4, 5); mandibles symmetrical, each with a subapical tooth; malar space about 2/3 diameter of front ocellus; occipital carina present, distinct to top of eyes; eyes prominent, slightly converging below, lower interocular distance greater than eye length; head from above slightly narrowing behind eyes; lateral sutures wide and deep, straight and parallel; postocellar area convex and wider than long; antennal furrow wide and shallow; frontal crest absent. Abdominal terga without paired white spots. Hindbasitarsus as long as remaining tarsal segments combined. Tarsal claws bifid, apical tooth longer than subapical tooth, with small basal lobe (indistinct but can be seen after dissection) (fig. 2). Forewing with 4 cubital cells; cell 2Rs as long as cell 1Rs at least along vein Rs; anal crossvein strongly oblique; veins M and lm-cu parallel; veins M and Rs+M meet Sc+R at same point. Hindwing with cells RS and M absent, petiole of anal cell slightly shorter than greatest width of cell, crossvein cu-a perpendicular to veins above and below, male without peripheral vein. This new genus belongs to the subfamily Allantinae and is near Malachiella Malaise in Malaise's 1963 key, but it is distinct from the latter by the nearly truncate clypeus(very deeply and narrowly circularly emarginated with narrow lateral teeth in Malachiella), and the presence of the occipital carina to the top of the eye (absent in Malachiella). The combination of the characters above should distinguish Dasmithius from all other Allantinae.Distribution: China. Dasmithius camelliae (Zhou and Huang), new combinationFemale: Black, shining. Antenna black; labial palpus dark brown; apical 3 segments of maxillary palpus brown; hind margin of pronotum, tegula, and cenchri whitish yellow; coxae and femora black, troehanters white, tibiae and tarsi brown. Wings subhyaline with yellowish lustre; stigma black with base yellowish; most veins blackish brown with veins M+Cu₁, Ci₁,, and M black.Antenna slightly compressed apically. Postocellar area rather convex, width 0.50mm, length 0.37mm; frontal crest absent; lateral sutures and transverse suture distinct; middle fovea deep and distinct; OOL:POL: OCL=61:29:51. Clypeus with coarse punctures; frons and ocellar triangle without distinct punctures, rugose; punctures of orbits, postocular area, and thoracic dorsum fine and sparse; abdomen without punctures. Clypeus, frons, orbits and prothorax with long whitish-yellow hairs; wing membrane with many black hairs. Sheath nearly uniformly slender in dorsal view, rounded in lateral view (Fig. 6, 7). Lancet Well sclerotized with 16—17 annuli (Fig. 1).Body length, 6.5—8.5mm; 3rd antennal segment. 0.66mm; 4th antennal segment 0.57mm; antennal segments 4+5, 1.10mm.Male: Color similar to female except lateral parts of hind margin of pronotum yellowish white; tegula blackish brown; legs with pale parts more dark or blackish brown. Body and legs with denser hairs. OOL: POL:OCL=51:29:53. Body length, 5.8—7.5mm; 3rd antennal segment, 0.74 mm;4th antennal segment 0.59mm; antennal segments 4+5, 1.28mm. Other characters as for female. Penis valve as in Fig. 3.Host plant: Camellia sinensis (L.)Habit: This species has one generation a year and overwinters as a prepupa in the soil. Adults emerge in the spring and deposit eggs in the newly sprouted leaves of the host. The larvae feed on the leaves and very serious damage may occur during outbreaks of these pests.