Megistopus lucasi ( Navas , 1912)

Badano, Davide, Aspoeck, Horst & Aspoeck, Ulrike, 2017, Taxonomy and phylogeny of the genera Gymnocnemia Schneider, 1845, and Megistopus Rambur, 1842, with remarks on the systematization of the tribe Nemoleontini (Neuroptera, Myrmeleontidae), Deutsche Entomologische Zeitschrift 64 (1), pp. 43-60 : 49-50

Megistopus lucasi ( Navas, 1912) Figs 1A, 2G, 3D, 4C, 7, 8 C–D

Nelees lucasi Navás, 1912 (ODescr): Banks 1913 (Com).

Neuroleon lucasi ( Navás, 1912): H. Aspöck and Hölzel 1996 (Distr), H. Aspöck et al. 2001 (Cat), Stange 2004 (Cat).

Megistopus mirabilis Hölzel, 1980 (misidentification): [Bernardi] Iori et al. 1995 (List), Letardi and Pantaleoni 1996 (Distr), Letardi 1998 (Distr), Letardi 2006 (Distr), Popov and Letardi 2010 (Biogeogr), U. Aspöck et al. 2015 (List).

Megistopus lucasi ( Navás, 1912): Güsten 2003 (Distr, Com), Badano and Pantaleoni 2014 (Biol), Letardi 2016 (Key), Badano et al. 2017 (photo).

Diagnosis.

Medium-sized antlion with a mottled light and dark brown body pattern. Wings relatively narrow. Forewing Rs arising at the height of Cubital fork. Forewing gradates shaded with brown, cubital mark brown.

Examined specimens.

Italy: Sardinia, Torre dei Corsari, 39°41,017'N 8°27,044'E, 28.V.2003, 50 m, H. and U. Aspöck and R.A. Pantaleoni leg, 3 ♀ (HUAC); Italy: Sardinia, Arbus (Oristano) / Torre dei Corsari, 39°41 ’23.09” N 8°27 ’14.50” E, coastal sand dunes /V.2010 D. Badano leg, 1 ♀ ex larva (DB); Italy: Sardinia, Arbus (Oristano)/ Torre dei Corsari, 39°41 ’23.09” N 8°27 ’14.50” E, coastal sand dunes /V.2011 D. Badano leg, 1 ♂ ex larva; Italy: Sardinia/ Chia (Cagliari), beach, XI.2011 (D. Badano), 1 ♂ ex larva (DB).

Redescription.

Colouration. Vertex ochre with paired dark markings. Paired blackish markings extend from the anterior margin of the vertex to the lateral margins of the frons, surrounding the base of the antenna. Frons light brown, except the lateral margins. Clypeus light brown with suffused dark markings. Labrum brown. Genae, maxillary and labial palpi testaceous. Antennae light brown, scape with dark brown suffusions, antennomeres darker basally (Fig. 3D). Pronotum ochre, dorsal side with paired dark brown, variegated stripes connecting the dark brown anterior and posterior margins; lateral margins mottled (Fig. 2G). Mesothoracic proscutum light brown anteriorly, posterior margins dark brown. Mesoscutum and mesoscutellum light brown with dark brown margins. Metathoracic proscutum brown with lighter margins. Metascutum and metascutellum with dark brown margins. Leg ochre, femur and tibia dotted (more thickly on the dorsal side) and with a dark marking near the articulation, tarsus ochre, darker near the articulation (Fig. 1A). Wings hyaline, venation brown with alternating pale dashes. Pterostigma whitish, with a faint brown proximal marking. Forewing gradates with a dark shade. Cubital mark elongated and clearly distinct (Fig. 4C). Abdomen mainly ochre, tergites with a darker median stripe on the anterior half and small darker spots on the margins. Abdomen covered with white and dark setae.

Dimensions (based on 2 specimens). Body length 20.31, 26.66 mm; forewing length 21.43, 26.61 mm, ratio width/length 0.24; hind wing length 20.8, 25.87 mm, ratio width/length 0.20.

Head. Vertex slightly inflated. Distal palpomere of labial palpi fusiform, relatively thin, palpimacula elliptical. Antennae clavate.

Thorax. Pronotum longer than wide (Fig. 2G). Thorax covered with short black setae. Legs extremely long and slender. Tibial spurs as long as the first tarsomere. Wings: relatively narrow with a rounded apex. Forewing costal area slightly wider at middle length. Forewing with ca. 6 presectoral crossveins. Origin of Radius sector at the same height of Cubital fork. Rs with more than ten crossveins. Branches of the Cubital fork divergent. CuP + 1A gently running toward the posterior wing margin but not abruptly. 2A gently curved before merging with 3A. Hind wing with 1 presectoral crossvein (Fig. 4C).

Male genitalia. As for genus. Gonocoxites 9 plate-like, converging apically (Fig. 8C). Ectoproct shell-like, ochre with a dark marking, covered with thin black setae (Fig. 7A).

Female genitalia. As for genus. Gonocoxites 8 dark brown, covered with thin black setae. Gonocoxites 9 and ectoproct covered with sparse stout setae (Fig. 7B).

Distribution.

The species is only known from few coastal localities of Algeria, Tunisia and Italy (Lazio and Sardinia) ( Letardi and Pantaleoni 1996 [sub Megistopus mirabilis ], Güsten 2003, Badano and Pantaleoni 2014) (Fig. 12).

Ecology.

Megistopus lucasi is an extremely rare species and is exclusively known from well preserved coastal sand dunes and beaches with junipers. The unmistakable larva of this species (see Badano and Pantaleoni 2014) is an ambush hunter, dwelling at the base of junipers and amidst their roots. The larva is parasitized by the generalist antlion parasitoid Micomitra stupida (Rossi) ( Diptera , Bombyliidae ) (Badano pers. obs.). This species of antlion is potentially endangered by human activities and exploitation of coastal sandy environments.