Dynastes neptunus Quenzel

Onore, Giovanni & Morón, Miguel-Angel, 2004, Dynastes neptunus Quenzel (Coleoptera: Scarabaeidae: Dynastinae); Descriptions of the Third Instar Larva and Pupa, with Notes on Biology, The Coleopterists Bulletin 58 (1), pp. 103-110 : 103-105

Dynastes neptunus Quenzel , Third-instar larva

( Figs. 1–16 )

The description is based on 4 third-instar larvae and 3 cast skins of third-instar larvae associated with immature adults collected at Ecuador: Cotopaxi, San Francisco de Las

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Pampas, Río Negro, 20-IV-2001, G. Onore, inside hollow trunk of ‘‘achiotillo’’ tree ( Alchornea sp. Euphorbiaceae ), 1,800 m (QCAZ; IEXA); 3 third-instar larvae reared from eggs laid by female collected at Ecuador: Cotopaxi, San Francisco de Las Pampas, 30-VI-1993, G. Onore, 1,600 m (QCAZ).

HEAD. Maximum width of head capsule 14–17 mm. Surface of cranium deeply and densely rugose punctate, reddish brown to dark brown. Frons ( Fig. 1 ) with 1–4 posterior frontal seta and 1– 2 exterior frontal setae on each side; each anterior angle of frons with 3–4 setae; remaining cranial surface with 4–8 dorso-epicranial setae and 3–20 para-ocellar setae on each side. Clypeus with 2 central setae and 2 lateral setae on each side. Labrum with lateral borders widely curved, and anterior border slightly asymmetrical, with 4–7 lateral setae on each side, 12–25 basal setae, and 2 central setae. Ocelli present, well defined, not pigmented. Epipharynx ( Fig. 2 ) with haptomeral process entire, prominent; right chaetoparia with 10–20 sensilla and 37–60 spine-like, short setae; left chaetoparia with 25–45 spine-like, short setae; acanthoparia with 9–13 stout, short setae; acroparia with 4–7 stout setae; pedium clear, wide; gymnoparia moderately reduced, without plegmatia; dexiotorma short and narrowed; sclerotized plate nearly triangular, strongly projected; sense cone surrounded by elongate sclerotized bar; laeotorma narrowed; pternotorma wide and rounded; crepis weakly defined at sides. Left mandible ( Figs. 3, 6 ) with 2 large scissorial teeth; inner margin with truncate tooth, sighlty sinuate at apex; molar area with well developed distal lobe (M1) and 2 basal, irregular lobes (M2, M3); acia acute; brustia reduced; ventral stridulatory area slightly elongated, with 35–56 transverse ridges; mesad of stridulatory area is a puncture with 4–5 long setae. Right mandible ( Figs. 4, 5 ) with 2 large distal scissorial teeth and 1 short, rounded tooth after scissorial notch; molar area with 3 irregular lobes; calx widened; brustia reduced; ventral stridulatory area nearly ovate, with 31–50 transverse ridges; mesad of stridulatory area is a puncture with 5–7 medium size setae. Maxilla ( Fig. 7 ) galea with 1 terminal uncus well developed; lacinia with 3 unci fused at bases; maxillary stridulatory area with 6–10 truncate teeth and wide anterior process. Labium ( Fig. 10 ) dorsal surface with 30–36 spine-like, short setae on the basal border, 18–22 central sensilla, and 35–42 stout setae on each side; hypopharyngeal sclerome asymmetrical, strongly produced on right side into rounded process, with 22–26 setae on right lateral lobe, and 50–56 setae on left lateral lobe. Dorsal surface of last antennal segment ( Figs. 8–9 ) with 5–10 sensory spots.

THORAX. Thoracic spiracles ( Fig. 13 ) 2.0– 2.5 mm long and 1.8–2.0 mm wide; respiratory plate dark reddish brown, shaped as closed ‘‘C’’; lobes of respiratory plate closely approximate; spiracular bulla weakly prominent, rounded. Pronotum with reddish brown, irregular formed lateral scleromes. Dorsum of prothorax with 4–6 transverse rows of 96–108 mixed long and short slender setae. Mesoprescutum with 3–4 transverse rows of 33–51 mixed long and short slender setae. Mesoscutum with 3 transverse rows of 80–91 mixed long and short setae. Mesoscutellum with 3 transverse rows of 48–49 mixed long and short slender setae. Metaprescutum with 4 transverse rows of 40–44 mixed long and short slender setae, intercalated with 1–2 spine-like short setae. Metascutum with 3–5 transverse rows of 57–140 mixed long and short setae, intercalated with 1–3 spine-like short setae. Metascutellum with 3 transverse rows of 56–61 mixed long and short setae, intercalated with 6–8 spine-like short setae. Tarsal claws of fore and middle legs ( Fig. 11 ) moderately elongate, with 2 internal, nearly basal setae, and 2 external, preapical setae. Hind tarsal claws ( Fig. 12 ) with apex slightly shortened, with 2 internal, nearly basal setae, and 2 external, preapical setae.

ABDOMEN. All abdominal spiracles ( Fig. 14 ) nearly of same diameter, 1.8–2.1 mm long and 1.8– 2.1 mm wide. Respiratory plate reddish brown, regularly shaped as a closed ‘‘C,’’ with 60–70 irregular ameba-like shaped ‘‘holes’’ ( Fig. 15 ) along any diameter; lobes of respiratory plates closely approximate; spiracular bulla weakly prominent, rounded. Chaetotaxy on dorsum of each abdominal segment as follows: prescutum I with 4 rows of 32–45 mixed, long and short slender setae (MLSSS) and 28–34 spine-like short setae (SLSS); scutum I with 4–5 rows of 94–99 MLSSS and 107–162 SLSS; scutellum I with 5–6 rows of 36–66 MLSSS and 88–110 SLSS. Prescutum II with 4–5 rows of 6–10 MLSSS and 106–127 SLSS; scutum II with 6–7 rows of 60–94 MLSSS and 150–229 SLSS; scutellum II with 6 rows of 34–58 MLSSS and 188–190 SLSS. Prescutum III with 5 rows of 6–10 MLSSS and 120–135 SLSS; scutum III with 4–6 rows of 82–230 MLSSS and 160–231 SLSS; scutellum III with 5–6 rows of 42–46 MLSSS and 165–204 SLSS. Prescutum IV with 4 rows of 6–9 MLSSS and 124–130 SLSS; scutum IV with 4–7 rows of 63–64 MLSSS and 194–226 SLSS; scutellum IV with 5–7 rows of 30–37 MLSSS and 174–202 SLSS. Prescutum V with 5 rows of 4–6 MLSSS and 121–137 SLSS; scutum V with 4–6 rows of 40–66 MLSSS and 205–224 SLSS; scutellum V with 6 rows of 28–32 MLSSS and 182–216 SLSS. Prescutum VI with 6 rows of 6–7 MLSSS and 146–178 SLSS; scutum VI with 3–7 rows of 35–44 MLSSS and 208–244 SLSS; scutellum VI with 6–8 rows of 50–62 MLSSS and 140–154 SLSS. Dorsum of segment VII with 12–16 rows of 146–184 MLSSS and 286–363 SLSS. Dorsum of segment VIII with 12–13 rows of 100–156 MLSSS and 240–280 SLSS. Dorsum of segment IX with 13–19 rows of 246–351 MLSSS and 358–394 SLSS. Upper anal lip with 110–187 MLSSS and 130–305 SLSS. Venter of abdominal segments I–IX each with an irregularly defined row of 16–20 MLSSS. Raster ( Fig. 16 ) without palidia; campus with 13–18 long, slender setae; teges formed by 50–100 mixed, long and short slender setae and 5–15 spine-like short setae; barbula sparse. Lower anal lip with 84–128 mixed, long and short slender setae and 130–305 spine-like short setae. Anal slit widely curved. Approximate body length: 70.5–190.5 mm.

Figures

Figs. 1–9. Dynastes neptunus, third instar larva. 1) Head, frontal view; 2) epipharynx; 3) left mandible, dorsal view; 4) right mandible, dorsal view; 5) right mandible, ventral view; 6) left mandible, ventral view; 7) left maxilla, dorsal view; 8) distal segment of left antenna; 9) distal segment of right antenna.

Figs. 10–16. Dynastes neptunus, third instar larva. 10) Labium and hypopharynx, dorsal view; 11) tarsal claw of mesothoracic leg; 12) tarsal claw of metathoracic leg; 13) prothoracic spiracle; 14) spiracle of abdominal segment VIII; 15) shape of holes of respiratory plate of abdominal spiracle; 16) venter of last abdominal segment.