Chelonus depressus
authorThomson 1874
synonyms
body
shape5 - 7 mill. (= 3 - 4.2 mm) [Th]. Body 3.3 mm long [P4][T14]. 4 - 6 mm. [M2][Te1].
colorblack [Th]. Black, a little shiny, covered with very fine pubescence [M2]
head
shapeHead in dorsal view (Fig. 1) transverse, twice as broad as long, eye almost one-third longer than temple, latter strongly rounded, occiput excavated. Eye in lateral view 1.75 times as high as wide; temple indistinctly wider than eye, broadest at its lower part (Fig. 2). Ocelli small, distance between fore and a hind ocelli twice, whereas distance between hind two ocelli three times greater than diameter of an ocellus; OOL (nearly) twice as long as POL (Fig. 1). Face more than twice as wide as high, inner margin of eyes parallel. Clypeus 1.35 times as wide below as high, its lower margin convex. Malar space 1.5 times as long as basal width of mandible and half as long as height of eye [P4]. The head is transversely narrowed posteriorly. The cheeks are not widened [Te1]. Longitudinal eye diameter 2 times longer than malar space [T11]. The head is rounded-narrowed behind the eyes, its width is twice its length. Eyes (dorsal view) 1.3 times as long as temples. The temples (side view) are slightly longer than the eyes. The distance between the anterior and posterior ocelli is twice the diameter of the ocellus. POL is 3 times the diameter of the ocellus and almost half OOL. Malar space 1.5 times basal width of mandible. The width of the face is twice its height [T14].
sculptureFace partly concentric partly rather transverse striate-rugose, subshiny, clypeus finely and dispersely punctate-subpunctate, shiny (Fig. 8). Head above striate-rugose [P4]. Frons finely striate, weakly shiny [Te]. The face and vertex are transversely rugose [T14]
colorMandible and palpi rusty brown [P4].
antenna
shape ♀Antennae thin, penultimate segment subtransverse [Th]. Antenna somewhat longer than head and mesosoma together. Third segment 3.1 times as long as broad, further segments gradually shortening and attenuating so that penultimate segment 1.5 times as long as broad [P4]. Antennae 16-segmented, their last segment almost transverse [Te1]. 3rd antennal segment 3 times as long as wide, preapical segment 1.5 times. Antennae slightly longer than head and mesosoma combined [T14].
shape ♂With 21 segments [M][M2]. Length: width ratio of flagellar segment slightly smaller than that of female, 3rd segment 2.5 times as long as broad [P4]. Antennae 21-segmented, very slender [Te1].
colorAntenna blackish with faint rusty suffusion [P4].
mesosoma
shapeMesosoma in lateral view about 1.5 times as long as high. Mesonotum between tegulae about one-fifth less broad than head [P4]. Mesosoma length 1.5 times its height [T14].
sculptureMesosoma roughly rugose to scrobiculate, mesonotum rugose, scutellum rugulose to uneven and shiny [P4]. Mesosoma slightly rugose [Te1]. Mesonotum rugose, scutellum more slightly rugose and shining [T14].
color
legs
shapeHind femur 3.3 times as long as broad, broadest at its middle; hind tibia and tarsus equal in length; basitarsus of hind leg as long as tarsal joints 2 - 4 [P4]. Length of hind femur 3.5 times its width [T14].
sculpture
colorLegs dark brown to brown, tibiae yellow to brownish yellow, hind tibia darkening; tarsi also yellow with brownish tint [P4]. Legs with a vague yellow pattern [Te1]. Hind basitarsus brownish-yellow. Hind tibiae dark-colored, occasionally yellowish-brown at base but without pronounced yellowish constriction [T11, key]. Hind metatarsus dark-colored. Tibia yellow to brownish yellow, hind tarsi darker [T14]
wings
shapeMarginal cell shorter than the stigma, r twice as long as 3-SR. [Th]. Fore wing shorter than body. Pterostigma (Fig. 3) 2.4 times as long as wide and slightly longer than R1, length of 1-R1 nearly half as long as that of pterostigma, latter issuing radial vein somewhat distally from its middle, r twice as long as 3-SR, SR1 straight, 2-SR almost four times as long as 3-SR [P4]. Marginal cell much larger than pterostigma. r twice as long as 3-SR [Te1]. 1-R1 1.5-2.0 times shorter than pterostigma [T11, key]. The marginal cell is almost half as long as the pterostigma [T14].
colorWings subhyaline, pterostigma opaque brownish, veins rather brownish-yellowish [P4]. The wings are almost light [T14].
metasoma
shape♀ Carapace one-fifth longer than mesosoma but shorter than head and mesosoma together, in dorsal view 1.6 times as long as broad, broadest at its middle (Fig. 4), in lateral view nearly evenly high anteriorly and posteriorly (Fig. 5); apically just incurved ventrally (Fig. 6). ♂ Carapace in dorsal view 1.7 times as long as broad, broadest at its middle [P4]. Carapace reflexed apically by about 0.1 its length; metasoma the highest in its middle part [T11], 1.5-1.65 times longer than wide [T11, key]. Metasoma oval, carapace bent forward apically by 0.1 of its length, 1.6 times as long as wide [T14].
sculptureBasal pair of keels short and converging. Carapace antero-posteriorly with somewhat weakening strio-rugosity, apically rather densely rugulose (Fig. 4) [P4]. Metasoma slightly reticulate-rugose [Te1]. The metasoma is longitudinally wrinkled, with sinuous rugae, but apically with denser and finer wrinkles [T14].
colorCarapace basally always black [P4]. Base of metasoma with light spots [Te1].
♀ ovipositorOvipositor sheath in lateral view as long as half of hind basitarsus [P4]. Ovipositor valves protrude 0.5 times the length of hind metatarsus [T14].
♂ apertureThe aperture is very small and almost round [Te1].
other info
distributionNL, SE [FE].
remarksClose to Ch. fenestratus Nees, from which it differs in the venation of the front wings and the delicate sculpture of the body [Te1].
hostsAcrolepiopsis assectella (ZELLER), Phthorimaea operculella (ZELLER)
