Metapteron xanthomelas (Lucas, 1857)

Ferreira, Vinicius De Souza & Costa, Cleide, 2015, A description of the Larva of Metapteron xanthomelas (Lucas, 1857) from the Restinga Forest of Southeastern Brazil (Coleoptera: Lycidae, Calopterini), Zootaxa 3915 (2), pp. 295-300 : 296-298

Metapteron xanthomelas (Lucas, 1857)

(Figs. 3–10)

Description of last instar larva. Body dorsoventrally flattened (Figs.3–4), integument creamy with dark–brown spots (Fig. 3).

Head hypognathous, small, transverse, integument strongly alveolate (Figs. 5, 6, 9), completely sclerotized except posterior region which is retractable into pronotum; dorsal setae: one pair of setae in frontal–anterior region, projected forward; one pair of anteromedian setae, produced from a small projection of the head; one seta on each anterolateral side, projecting in the same direction as antenna. Nasale small and acuminate (Fig. 6). Stemma absent. Antenna (Fig. 6) two segmented, antennomere 1 ring–shaped, connate to head, wider than longer; antennomere 2 elongated, sclerotized, with two pegs and three setae triangularly arranged.

Mandibles ( Figs. 9 , 10) symmetric, each falciform, tripartite, outer part (sheath) broad at base, tapering apically, with anterior and an outer condyles; stiletto (Fig. 10a) slender, acuminate, articulate with the hypopharyngeal lobe (Fig. 7), with sheath (Fig. 10b) and shutter; shutter forming a ring, enclosing sheath and stiletto (Fig. 10c), a conspicuous long seta on exterior basal surface of mandible ( Fig. 9 , right side).

Maxillolabial complex strongly alveolate. Labial palp 2-segmented, basal segment wider, apical segment elongate (Fig. 5). Maxillary palp 3-segmented (Fig. 8), basal segment alveolate, with a single seta; palpomeres 2-3 elongate, 3 with 5 setae, two on basal half and three ones pre-apical. Hypopharynx (Fig. 7) with apodemes apically convergent, median lobe preeminent, rounded apically.

Thorax slightly narrower than abdomen, transverse, dorsally undivided. (Figs. 3, 4). Pronotum, mesonotum and metanotum with lateral margins nearly rounded, and notal disc slightly dark. Legs short, coxae annular, trochanters undivided [femur and tibiae missing].

Abdominal terga 1-8 conspicuously lobed, lighter colored on margins, with several small, sparse dark brown macula (Fig. 3), bearing very small divergent setae laterally. Tergum 9 (Fig.5) without urogomphi, tergum10 ventrally bearing a pygopodium–like process.

Material examined. Brazil. Itanhaém, São Paulo. Cidade Santa Júlia. One larva fixed, 1 reared to adult, 1 penultimate instar exuvium fixed, and 1 last instar exuvium fixed, 16.VI.1979, L. R. Fontes & P. S. Terra cols. Flask number 5383, cabinet 4, drawer 13. ( CIC – MZUSP). According to the notes of the reared specimens the larvae were collected under decaying wood of a palm tree.

Discussion. The larva of M. xanthomelas resembles other Calopterini larva by having abdominal segments 1-8 conspicuously lobed ( Costa et al., 1988 for Calopteron sp.; Bocak & Matsuda, 2003 for C. terminale Say, 1823 ). However, the M. xanthomelas larva herein described is easily recognized from the other known Calopterini larvae by the absence of urogomphi, the dorsal abdominal segments without any apparent division, and by the strongly alveolate ornamentation on the head (Figs. 5, 6, 9).

As in other known lycids, the mandibles of M. xanthomelas are tripartite and consist of a sheath, a stiletto and a shutter, resembling the ones described for Lycus trabeatus (Guérin–Meneville, 1835) ( Kazantsev, 2003) and for Macrolygistopterus aff. subparallelus Pic, 1930 (Costa & Vanin, 2012).

Figures

FIGURE 9. Metapteron xanthomelas (Lucas, 1857), exuvium larval, detail of nasal, hypopharynx and mandibles. FIGURE 10. Metapteron xanthomelas (Lucas, 1857), larva, schematic arrengement of tripartite mandible, (a) Sheath, (b) Stiletto, (c) Shutter.