Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 79. (Budapest 1987)

Altenhofer, E. ; Zombori, L.: The species of Heterarthrus Stephens, 1835 feeding on maple (Hymenoptera, Tenthredinidae)

the middle by a transverse furrow, its front margin truncate. Anterior tentorial pits deepening with almost parallel sides, shallow and black. Interantennal area bulging, divided by a long black stripe that is guttiformly dilated apically. Superior tentorial pits umbilicate, sitting at the bottom of a basinlike depression. Frontal area bulging, not delimited by keels. Frons divided in the middle by a longitudinal depression that is somewhat broad just below the median ocellus becoming very narrow downwards and ending well before the imaginary line connecting the upper margins of the antennái sockets. Postocellar area short, 1.5 times as long as diameter of an ocellus, delimited on either side by a large guttiform pit, in the middle with a shallow, longitudinal furrow. Head behind eyes strongly contracted. Antenna black but two-three apical joints entirely reddish brown. The number of joints 12, in exceptional cases 11. Thorax black with the following parts yellowish white: very narrow lateral and hind margin of pronotum, almost entire tegula (basally with a diffuse, brownish smudge). The acrotergite of mesonotum with a wide, transverse groove at its hind margin. Anterior lobes of mesoscutum coriaceous, lateral lobes also with a longitudinal coriaceous band. Mesoscutellum shining with some weak, scattered punctures all over the surface, mesothoracic postscutellum highly polished. Cenchri dirty white. Metanotum depressed, metascutellum transversally wrinkled. Mesopleuron covered with short pubescence, mesosternum bare and shining, with very weak coriaceous surface sculpture. Legs black, apices of coxae, femora, entire tibia of fore and middle legs yellowish brown, tarsi mostly infuscate. Wings light brownish infuscate, veins and pterostigma brown. Second anal cross-vein straight adjoining first discoidal cell somewhat behind its middle. Abdomen black. First tergite densely punctate, other tergites shining with dense, transverse wrinkles throughout. Sternal plates entirely dark brown. Hypopygium deeply emarginated in the middle as depicted in Fig. 2. Sawsheath in lateral view resembling a knife-blade, in dorsal view narrowing to a blunt point. Bilateral bristles bent and ponting backwards. A portion of the saw showing the construction of the teeth, as shown in Figs 5-6. Length: 3.5-4.5 mm. — Alar expanse: 9-11 mm. No male. Larva. —Yellowish white. Head light yellow, frontal suture dark brown. Labrum truncate in front margin. Clypeus triangularly excised anteriorly. The other cephalic features are similar to those of leucomelus. Pronotum yellowish white in the last instar larva, though in the younger stadia its bears two large, indistinct brown spots, other thoracic and abdominal tergites yellowish white. Prosternum similarly, though very weakly marked as in leucomelus. Meso- and metasternum with a a more or less oval spot each. Anal ring composed of a small number of irregular, dentiform sclerotizations (Fig. 15). — Length: 9 mm. The larva feeds only in the leaves of Acer pseudoplatanus found in open landscape, along roads and in hedges. The egg is laid in one of the apices of the leaf (see ALTENHOFER 1980b: 125, Abb. 2b) and the emerging larva mines towards the middle of the leaf eating out a large blotch-like part (Fig. 14). When the larva is fully fed it spins a cocoon inside the leaf, however, before constructing its case with its mandibles it perforates the upper epidermis of the leaf at regular intervals in circular fashion. Having spun the cocoon the larva lays resting. Owing to this peculiar behaviour, the perforated, circular part of the leaf begins to dry and the epidermis breaks between two perforations, eventually causing the cocoon to fall to the ground. (On one occasion the second author observed the "jumping off" of the cocoon.) The larva feeds in the leaf until the third decade of June at the lower altitudes. However, in higher regions (above 500 m) the spinning of the cocoon is completed somewhat later, sometimes in the middle of July. Occasionally mass outbreaks occur when even 10 mines may be counted in one leaf. The species is entirely parthenogenetic. The rearings produced a total of 260 females, and no males at all. Material examined. — Austria: Köttlach, 13. III. 1977, larva ex Acer pseudoplatanus 10. VII. 1975, leg. Altenhofer (1 specimen); St. Pölten, 19. V. 1977, larva ex A. pseudoplatanus 16. VI. 1976, leg. Altenhofer (1 specimen); Kammern, 11. V. 1977, larva ex A. pseudoplatanus 8. VII. 1976, leg. Altenhofer (47 specimens); St. Pölten, U.V. 1977, larva exA. pseudoplatanus 16. VI. 1976, leg. Altenhofer (60 specimens); Kammern, 12. V. 1977, larva ex A. pseudoplatanus 8. VII. 1976, leg. Altenhofer (45 specimens); Kammern, 15. V. 1977, larva ex A. pseudoplatanus 8. VII. 1976, leg. Altenhofer (1 specimen). — A total of 155 specimens.