Distoleon annulatus (Klug, 1834)

Acevedo, Fernando, Monserrat, Víctor J. & Badano, Davide, 2013, Comparative description of larvae of the European species of Distoleon Banks: D. annulatus (Klug, 1834) and D. tetragrammicus (Fabricius, 1798) (Neuroptera, Myrmeleontidae), Zootaxa 3721 (5), pp. 488-494 : 489-491

Distoleon annulatus (Klug, 1834)

Examined specimens. SE Spain, Almería: Casillas de Atochares, Rambla de Artal): 2 third instar larvae (7.V.2011, F. Acevedo and V. J. Monserrat leg., 1 third instar larva; 29.VI.2011, F. Acevedo and V. J. Monserrat leg., 1 third instar larva); Almería: San José, Cabo de Gata: 1 third instar larva (5.VII.2013, D. Badano, F. Acevedo and V. J. Monserrat leg.).

Description. Size. Average body length (without mandibles) 8.80 mm; head capsule length 2.80 mm, head capsule width (widthest part) 2.45 mm, mandible length 2.54 mm, ratio head capsule width/length 0.87, ratio mandible length/head capsule length 0.9.

General coloring. Ochre with a dark pattern (Fig. 1), ventral side paler with some dark brown spots (Fig. 5); head ochre, with two large triangular dark markings on the dorsal side, lateral side with conspicuous dark markings, ventral side pale with the anterior zone dark (Figs. 1, 2); mandibles dark brown, paler at teeth insertion and darker at the apex of the mandibles and teeth (Fig. 2).

Head. Longer than wide, trapezoidal, external margin of the labrum with a small median pale incision, delimited by two small lobes; head capsule covered with dark setae on the dorsal and ventral surface, longer on lateral sides; dorsal side bearing dolichasters (Figs. 2, 6); antennae longer than the eye tubercle, brown with the scape and pedicel darker (Figs. 2, 6); eye tubercles large and prominent, with seven black stemmata (Fig. 2); mandibles comparatively strong, shorter than the head capsule, provided with 3 pairs of equidistant teeth of which the apical one is the strongest (Fig. 2, 6); 1 seta between each pair of teeth, few (4) setae between the insertion of the mandible and the basal tooth, external margin of the mandible with black long and fine setae until the distal tooth (Figs. 2, 6); labial palpi dark in color, distal segment longer than the others (Fig. 7).

Body. Elliptical in shape, covered by black setae and provided with thoracic scoli (Figs. 1, 5).

Thorax. Ochre with two darker longitudinally lines; pronotum dorsally covered by numerous short setae, larger on lateral sides; mesothoracic spiracle subcylindrical, borne on tubercle (Fig. 3); mesothoracic scoli prominent, especially the anterior pair (Figs. 1, 3).

Legs. Pale in colour, with brown spots in the centre and distal extreme of the last tarsomere, covered by dark, large and fine setae, with two brown curved claws in each leg (Figs. 5, 8).

FIGURES 1–9. 3rd instar larva of Distoleon annulatus (Klug, 1834) ( Spain, Almería: Casillas de Atochares, Rambla de Artal). 1. Habitus, dorsal view; 2. Head, dorsal view; 3. Detail of thorax, dorsal view; 4. Abdomen, dorsal view; 5. Habitus, ventral view; 6. Head, ventral view; 7. Detail of palpomeres; 8. Thorax and abdomen, ventral view; 9. Detail of VIII and IX sternites, ventral view.

Abdomen. Dorsal side with a median and two lateral series of dark markings creating lines (Figs. 1, 4); ventrally pale with few brown spots, sternite VIII with two spots in proximity of the odontoid processes; abdomen thickly covered by black setae (longer and broader on scoli) (Figs. 5, 8); abdominal spiracles slightly pronounced, brown; VIII sternite equipped with odontoid processes (Fig. 9); IX sternite with a ventro-posterior pair of spiniform setae and a distal pair of small but protruding rastra equipped with 4 pairs of sub-equal digging setae, of which the inner pair is slightly smaller than the others (Fig. 9).

Biological and behavioral notes. The larvae were observed in the SE of Spain, an area characterized by a semiarid climate. They were collected by sieving the dry and fine substratum contained in rock cavities, and also in loose arid soil among grasses and rocks. They can move backward and forward rapidly, but they always bury backwards. They remain buried waiting for preys; if they are disturbed, they feign death for some minutes. When the larvae are mature, they spin slightly oval cocoons covered with soil particles.