Palpares libelluloides (Linnaeus, 1764)

Badano, Davide & Pantaleoni, Roberto Antonio, 2014, The larvae of European Myrmeleontidae (Neuroptera), Zootaxa 3762 (1), pp. 1-71 : 10-16

Palpares libelluloides (Linnaeus, 1764)

( Figs. 2A , 7 )

Despite the wide distribution and striking appearance of this species, the original descriptions and reports of its larva are surprisingly rare. The larva was described and illustrated for the first time by Brauer (1854) and later by Hagen (1873) and Redtenbcher (1884). Following descriptions are mostly based on these older accounts ( Steffan 1975; Gepp & Hölzel 1989; Gepp 2010; Krivokhatsky 2011). In the past, the larva of this species was often confused with the equally unmistakable larvae of Acanthaclisini simply for their large dimensions (e.g. Navás 1923).

Examined specimens. France. Aniane 44, Les Bernayves , IX.1985 (J. M. Maldes), 2 L3 (coll. B. Michel) . Italy. Liguria, Genova , terrapieni or. (= oriental banks), V.1908 (G. Mantero), 1 L3 (coll. Museo civico di Storia naturale “G. Doria ”) . Liguria, 5 L1 laboratory-reared from a female collected at Cipressa ( Imperia ), scrubland, VII.2010 (D. Badano) . Liguria, Perinaldo ( Imperia ), olive grove soil, VI.2011 (D. Badano), 1 L1 laboratory-reared to L2 . Abruzzo, Cerchio ( L’Aquila ), Le Coste, III.1994 (Stornelli & G. Osella), 1 L3 .

Description of 3 rd instar larva. Size (based on 4 specimens): BL 21.89 mm; HL 5.50 mm (5.15–5.85), HW 5.46 mm (5.36–5.57), ML 5.54 mm (5.33–5.95), HW/HL 0.99, ML/HL 1.01. General colouring brown with not contrasting darker markings, ventral side very pale, whitish; head capsule brown, lateral sides with large markings, ventral side of the head pale brown with dark margins, isolated brown spots are disposed at the insertion of bristles ( Fig. 7h ); mandibles black; legs pale; setae of the body black. Head quadrate, as long as wide, with large ocular tubercles ( Fig. 7c ); margin of the labrum with a pronounced median incision ( Fig. 7b ); dorsal surface with a ridge starting at the very deep tentorial pit and ending laterally with a pair of tubercles ( Fig. 7i ); mandibles robust, as long as the head capsule; median tooth larger than the other teeth, median and apical mandibular teeth closer than the median and basal teeth ( Fig. 7a ); interdental mandibular setae extremely short: (~5)(3–4)(0)(0); a series of stout setae is distributed on the external margin of the mandibles; head surface covered by pale dolichasters. Pronotum with 4 dorsal parallel series of stout setae; mesothoracic spiracles pale on a short tubercle, surrounded by black hairs; first pair of thoracic setiferous processes ( Fig. 7e ) with forward directed tuft of black setae at its base ( Fig. 7d ). Abdominal spiracles large and dark. VIII abdominal sternite with large odontoid processes ( Fig. 7g ); IX sternite with fossoria ( Fig. 7f ).

Bio-ecology. P. libelluloides is associated with open and warm but not excessively arid environments such as grasslands, scrublands, meadows and glades. The larvae live in soil of the biotopes frequented by the adults, buried into vegetal debris and gravel among roots and stones. This species appear to prefer a coarse substratum and it is normally absent from sites with the presence of fine sand, such as coastal dunes.

Distribution. Widespread species in the western Palaearctic.

Remarks. The 1 st instar larva of Palpares shows remarkable differences from the later stages: the odontoid processes of the VIII sternite are noticeably smaller and the IX sternite is equipped with rastra bearing 4 digging setae. Nevertheless, the 1 st instar larva of Palpares is equally unmistakable from other antlions due to the combination of prominent ocular tubercles, the median mandibular tooth largest and presence of thoracic pedunculated setiferous processes. In the Iberian Peninsula P. libelluloides is sympatric with the only other European congener, P. hispanus Hagen, 1860 ; the larva of the latter is not adequately known and the old existing descriptions are unconfirmed or misidentifications ( Hagen 1873; McLachlan 1873).

Figures

FIGURE 2. IX and VIII abdominal sternite of 3rd instar larvae of Palparini, Myrmecaelurini, Nesoleontini and Acanthaclisini. A, Palpares libelluloides; B, Myrmecaelurus trigrammus; C, Cueta beieri; D, Cueta lineosa; E, Acanthaclisis occitanica; F, Synclisis baetica. Scale bar: 1 mm.

FIGURE 7. Palpares libelluloides (Linnaeus, 1764), 3rd instar larva (France: Hérault, Aniane). Dorsal (above), ventral (middle) and lateral (below) view; a–i: diagnostic characters, see species description.