Euroleon nostras (Geoffroy, 1785)

Badano, Davide & Pantaleoni, Roberto Antonio, 2014, The larvae of European Myrmeleontidae (Neuroptera), Zootaxa 3762 (1), pp. 1-71 : 65-67

Euroleon nostras (Geoffroy in Fourcroy, 1785)

( Figs. 1 , 5I , 6I , 34 )

The pit-building behaviour of this species attracted the attention of early naturalists such as Réaumur (1742) and Rösel von Rosenhof (1755) who treated its life history. Nevertheless the first scientific description was realized only a century later by Brauer (1857) actually naming this species Myrmeleon formicarium (see also under M. formicarius ). Probably due its abundance in Europe, this antlion was extensively redescribed and it is probably one of the better known member of the family ( Hagen 1873; Redtenbacher 1883, 1884; Eglin 1939, 1940; Friheden 1973; Steffan 1975; Gepp & Hölzel 1989; Gepp 2010; Krivokhatsky 1994, 2011). The account of Principi (1943) is particularly noteworthy for its accuracy and level of detail.

Examined specimens. France. Gard, Beauvoisin , relict sand dunes, VIII.2011 (D. Badano), 4 L3 . Germany. Saxony, Dresden , VIII.2010 (C. Kehlmaier), 4 L3 . Italy. Val d’Aosta, Aymavilles (Aosta), Pont d’Ael , rock overhang, VIII.2012 (D. Badano), 2 L3. Lombardy, Zelo Buon Persico (Lodi), VII.2010 (D. Scaccini), 7 L3 ; same locality, X.2011, 1 L3. Liguria, Mt. Toraggio (Imperia), rock overhang, VII.2010 (D. Badano), 2 L3. Lazio, Roma (Roma), Prataglia di Cervara, VI.2010 (M. Gigli), 1 L3. Lazio, Roma (Roma), Mt. Mario , IX.2010 (A. Alfonsi & C. Cesaroni), 1 L3 . Greece. Corfu, Nissaki , V.2012 (D. Badano), 1 L3 . Turkey. Cappadocia, 2 km from Göreme , V.2010 (A. Letardi), 1 L3 . Georgia. Tbilisi (surroundings), VIII.2011 (C. Deiaco), 25 L3 .

Description of 3 rd instar larva. Size (based on 46 specimens): BL 9.32 mm; HL 2.24 mm (1.91–2.55), HW 1.84 mm (1.57–2.13), ML 2.26 mm (2.00–2.60), HW/HL 0.82, ML/HL 1.01. General colouring reddish brown with dark markings, ventral side pale with large dark markings; dorsal side of the head capsule with an anterior pair of spots and a V-shaped brown marking, ventral side of the head pale mottled with brown, with a median pair of elongated markings and a pair of spots ( Figs. 5I , 34c ); mandibles pale brown, lateral sides of the head with dark markings. Head longer than wide; mandibles as long as the head capsule ( Fig. 34a ); interdental mandibular setae (~4)(2)(2)(1); dorsal side of the mandible covered by short setae both on the external and internal margin, ventral side with a thick covering of short setae external to the maxilla, reaching the basal tooth ( Figs. 5I , 34b ) and with sparse setae disposed internal to the maxilla ( Fig. 34a ). Posterior margin of VIII sternite covered by hair-like setae ( Fig. 6I ; 34d ); IX abdominal sternite with an anterior row of 4 digging setae and with two short rastra each bearing each 4 digging setae ( Figs. 6I , 34e ).

Bio-ecology. E. nostras is an euryoecious species reported from a vast array of biotopes from the sea-level to mountains, despite avoiding very xeric environments. The pits are built in sheltered conditions wherever a suitable loose substratum is present, thus the larvae are normally found under rock overhangs, near escarpments, at the entrance of caves and at the base of trees. Generally E. nostras prefers woody environments and in open sites, such as river banks and dunes, it is found in protected conditions. The requirement for sheltered corners predisposes this antlion to live in proximity of artificial structures such as buildings, rock walls and bridges. Interestingly the larvae of E. nostras are often found in unreachable corners for themselves such as tree holes, probably representing oviposition sites of females

Distribution. Widespread in the western Palaearctic.

Remarks. The larvae of E. nostras are noticeably similar to the species of M. formicarius- group in the overall habitus and the disposition of digging setae on the IX abdominal sternite, however they are recognizable for the absence of spots on the metathoracic pair of legs. Moreover the reddish colour of the body permits an easy identification of this antlion.

Figures

FIGURE 1. Taxonomic characters of larvae of Myrmeleontidae. A, Euroleon nostras dorsal and ventral views; B, head of Myrmeleon inconspicuus; C, head of Macronemurus appendiculatus; D, IX and VIII sternite of Myrmecaelurus trigrammus; E, IX and VIII sternite of Creoleon lugdunensis.

FIGURE 5. Head of 3rd instar larvae of Myrmeleontini, ventral view; A, Myrmeleon formicarius; B, Myrmeleon gerlindae; C, Myrmeleon punicanus; D, Myrmeleon bore; E, Myrmeleon inconspicuus; F, Myrmeleon mariaemathildae; G, Myrmeleon hyalinus; H, Myrmeleon fasciatus; I, Euroleon nostras.

FIGURE 6. IX abdominal sternite of 3rd instar larvae of Myrmeleontini, ventral view; A, Myrmeleon gerlindae; B, Myrmeleon punicanus; C, Myrmeleon formicarius; D, Myrmeleon bore; E, Myrmeleon inconspicuus; F, Myrmeleon mariaemathildae; G, Myrmeleon hyalinus; H, Myrmeleon fasciatus; I, Euroleon nostras. Scale bar: 1 mm.

FIGURE 34. Euroleon nostras (Geoffroy in Fourcroy, 1785), 3rd instar larva (Italy: Latium, Roma, Prataglia di Cervara). Dorsal (above), ventral (middle) and lateral (below) view; a–e: diagnostic characters, see species description.