Platycrepidius dewynteri Chassain

Rosa, Simone Policena, Albertoni, Fabiano F. & Bená, Daniela De Cassia, 2015, Description of the immature stages of Platycrepidius dewynteri Chassain (Coleoptera, Elateridae, Agrypninae, Platycrepidiini) from Brazil with a synopsis of the larval characters of Agrypninae tribes, Zootaxa 3914 (3), pp. 318-330 : 321-325

Descriptions of Platycrepidius dewynteri Chassain immatures

Mature larva ( Figs. 3, 4 , 12–28 ). Length: 24–28 mm. Body ( Figs. 3, 4 , 12–14 ) elongate, parallel–sided, strongly flattened. Dorsal and ventral face yellow, except for pronotum, anterior margin of mesonotum, legs and apices of urogomphi brown; head dark reddish-brown, mandibles black.

Head (15–17) prognathous, dorsal surface densely punctate, posterior margin straight. Epicranial stem present. Frontal arms ( Fig. 15 ) lyriform; a single convex stemma on each side near base of antenna ( Fig. 16 ). Nasal ( Fig. 20 ) with a median tooth sided by two lateral pairs of teeth, of which the inner is smaller than the median tooth, the outer is as long as the median tooth. Adnasalia as long as the median tooth. Inner lateral tooth of nasal with several setae, adnasalia with two setae; area between outer tooth of nasal and adnasalia with several setae and microdenticles. Lateral part of frons with a pair of setae near the posterior edge, median part with a pair of setae near the lateral edge. each epicranial half with three lateral and three dorsal setae posteriorly to antenna and one seta near the posterior part of frons. Antenna ( Fig. 18 ) 3-articulated; 2–4 setae ( AS 2) on antennomere 1 and 2; antennomere 2 with one small conical sensorium at apex; apical antennomere narrow and very short with one long thick seta apically ( AS 3), located on antenommere 2 lateroapically. Mandibles ( Figs. 21, 22 ) narrow, tapering to apex; unidentate; mesal surface of mandibular base with a penicillus brush-like with short setae; dorsolateral margin with one seta near middle. Hypocephalic carina ( Fig. 17 ) almost reaching the base of head, with one seta anteriorly and three setae posteriorly. Mouthparts ventrally ( Figs. 17, 19 ) with surface densely punctate; maxillae with cardines narrow and elongate, contiguous to each other; stipites elongate with five setae anterolaterally near the membranous edge, galea 2-segmented, glabrous; palp 4–segmented, setose at inner and anterior margins; lacinia membranous with a fringe of setae. Postmentum triangular widened anteriad, with a pair of setae near midlength and a pair posteriorly; prementum with a pair of setae at anterior margin between palpi, labial palp 2–segmented, widely separate, basal palpomere glabrous, apical palpomere with several setae at inner and anterior margins. Hypopharynx densely clothed with long plumose setae laterally, with 11–12 campaniform organs and 15–20 stiff setae each side.

Prothorax ( Figs. 12–14 ) 0.8–0.9x as long as meso– and metathorax combined; metathorax 1.1x longer than mesothorax. Pronotum ( Figs. 12, 13 ) with five setae laterally, two pairs of setae near the anterior margin and one pair on hind angle. Prosternum ( Fig. 14 ) triangular, glabrous. Meso- and metanotum ( Figs. 12, 13 ) with 2-3 setae at lateral margin, one pair of setae anteriorly and one pair posteriorly. Mesothoracic spiracle located anteriorly in small conical prominence on the pleura. Legs ( Figs. 23–25 ) stout with several short and wide spiniform setae and a few longer stiff setae ventrally and apically near base of pretarsus. Pretarsus stout, shorter than tibia, base translucent with two setae.

Abdomen ( Fig 12–14 , 26–28 ) about 0.8x narrower than thorax. Terga I-VIII with two lateral setae each side (one ventrally and one dorsally to the spiracle), a pair of lateral setae near anterior margin and four pairs of setae near posterior margin. Spiracles located in small conical prominences on pleurae I-VIII anteriorly. Sterna I-VIII with three anterior and one posterior pairs of setae. Segment IX ( Figs. 26–28 ) 1.5 longer than VIII, with posterior margin notched at middle forming a bifurcate urogomphi; lateral margin (including urogomphi) with five spiniform tubercles each with one seta, dorsal anterior surface with a pair of oval depressions; urogomphi with a subapical spine dorsally directed ( Fig. 27 ) and dorsal surface with a few long setae and scarce punctures; lateroventral and dorsolateral borders densely setose with long setae. Segment X subrectangular ( Fig. 28 ) ventral with a pair of anal hooks, lateral margins with small tubercles.

Pupa ( Figs. 6, 7 , 29–34 )

Length 19 mm; width 5 mm. Adecticous, exarate. Color cream white to yellow; glabrous; pronotum ( Fig. 29 ) with one pair of branched prolongations at anterior margin ( Fig. 32 ) and one branched prolongation at apex of each hind angle ( Fig. 33 ). Abdomen with eight pairs of spiracles, the last one reduced; tergum IX with apex sclerotized, bifurcate with lateral small prolongations ( Fig. 34 ) and covered by small tubercles.

Material examined. BRAZIL. Pará: Belém, Icoaraci district, urban area, in Bromeliaceae [ Werauhia cf. gigantea (Mart. ex Schult. & Schult. f.) J.R.Grant], 08°17’54.28”S 48°29’23.07”W, 08.ii.2010, F.F.Albertoni col., S.P.Rosa det. 2012, 2 mature larvae, 1 entire larval exuvia, 5 cephalic exuviae, 1 pupal exuvia, 1 adult. ( MZUSP). Biological notes. During the first 15 days, while the Platycrepidius dewynteri larvae were kept in the same vessel, the larvae were observed killing the termites but not eating them. They ate the whole body of the termites on the following days. We observed cannibal behavior when the smallest larva was preyed by the others, then we separated the larvae in individual containers.

In individual containers, each larva was fed with winged termites and Tenebrio molitor larvae. It was observed that Platycrepidius dewynteri larvae predated T. molitor larvae around 17 mm length, but did not eat bigger larvae. The affinity of the Platycrepidius dewynteri larvae for water was noticeable. In the majority of the observations the larvae were at the bottom of the recipient where there was a thin layer of water or the most humid part of the substrate. The larva showed a conspicuous behavior during the pupation. It gathered all the litter that was inside the vessel in the middle of it ( Fig. 5 ) and built a pupal chamber in the center of the gathered litter. The larvae did not show any bioluminescence, even after being disturbed.

Figures

FIGURES 1 – 5. 1, 2, Bromeliad Werauhia cf. gigantea. 1, litter where the larvae were found; 2, entire specimen hold by 1.83 m high collector. 3 – 5, Platycrepidius dewynteri Chassain. 3, 4, mature larva (lateral, dorsal) and rearing substrate; 5, rearing substrate arranged by larva for pupation.

FIGURES 12 – 14. Platycrepidius dewynteri Chassain. Mature larva. Habitus: 12, dorsal; 13, lateral; 14, ventral.

FIGURES 15 – 28. Platycrepidius dewynteri Chassain. Mature larva. 15 – 17, head (dorsal, lateral, ventral); 18, left antenna (lateral, external); 19, maxillae and labium (ventral); 20, frons (dorsal); 21, 22, mandible (dorsal, ventral); 23 – 25, legs of pro-, meso- and metathorax; 26, segment IX (dorsal); 27, 28, segments IX and X (lateral, ventral).

FIGURES 6 – 11. Platycrepidius dewynteri Chassain. 6, 7, pupa with larval exuvia (dorsal, ventral); 8, adult 3 days after emerged, with larval and pupal exuviae, 9 – 11, adult habitus (dorsal, ventral and lateral).

FIGURES 29 – 34. Platycrepidius dewynteri Chassain. Pupa. 29 – 31, habitus (dorsal, ventral, lateral); 32, prolongation of anterior margin of pronotum (dorsal); 33, prolongation of the hind angle of prothorax (dorsal); 34, abdominal apex (ventral).