Ampulex compressa (Fabricius)

Fox, Eduardo Gonçalves Paterson, Buys, Sandor Cristiano, Mallet, Jace- Nir Reis Dos Santos & Bressan-Nascimento, Suzete, 2006, On the morphology of the juvenile stages of Ampulex compressa (Fabricius 1781) (Hymenoptera, Ampulicidae), Zootaxa 1279, pp. 43-51 : 45-49

Ampulex compressa (Fabricius)

Last larval instar

Body: General body form as illustrated for Sphex tepanecus Saussure in Stehr (1987). Pale yellow, length ranging from 0.9 cm (penetrating larva) to 2.5 cm (fully fed mature larva), dorsoventrally compressed and rather flattened ventrally and rounded dorsally; more tapered anteriorly than posteriorly. Its maximum width ranged from 0.2 cm (penetrating larva) to 0.9 cm (fully fed mature larva) at fifth and sixth abdominal segments. Pleural lobes prominent. Most body segments divided into two annulets dorsally, integument slightly granulose. All spiracles brown and located inside pronounced depressions ( Fig. 1 A). Spiracular atrium apparently unornamented; peritreme with five valve­like projections ( Fig. 1 A). Anus terminal.

Head capsule: Subcircular; measuring 1.1 mm long and 1.0 mm in maximum width with distinct depressions in antennal and coronal regions ( Fig. 1 B). Anterior tentorial arms and pleurostoma unpigmented and discrete, hypostoma dark brown, parietal bands feeble ( Fig. 1 C). Depressions in clypeal region; metopic suture strongly pronounced and continuous with the frontal suture ( Fig. 1 B). Antennal orbits discrete and circular (diameter = 40 μm), with 3 sensilla apically. Cephalic surface with few punctures, mainly concentrated in clypeal region and with a distinct group of 6 punctures in subgenal area (not shown).

Mouthparts: Labrum 562.6 ± 253.9 m (n=5) wide, strongly bilobed ( Fig. 1 C, 1D), pigmented mesally and with 30–32 surface punctures, setae (8 m long) and basiconic sensilla (10 m diameter) ( Fig. 1 D). Epipharynx densely spinulose mesally with 4 m spines directed apically, shorter spines present at the lobes’ extremities, but these are absent on the sensory area, which contains 8–10 scattered basiconic sensilla (7–8 m in diameter) ( Fig. 1 E). Mandible is 418.2 ± 204.4 (n=4) m long, brown, darker at apex and articulations, bearing 4–5 teeth, with neither punctures nor setae ( Fig. 1 C). Maxilla with few setae (about 12 m); its inner basal portion with flattened papillae margined with short spikes; lacinial area with 3–5 m­long spines ( Fig. 1 F). Pigmented maxillary palpus stout, 60 m long x 55 m wide, with three basiconic sensillae apically; galea pigmented, 30 m long x 30 m wide (not shown). Salivary lips with a deep medial groove just above a transverse spinneret with prominent raised lips, margined with spoon­like papillae on the upper lip which also bears short spikes internally ( Fig. 2 A). Labium about 329 m wide, and pigmented at the sides; bearing weakly pigmented, cone­shaped, 47 m long x 61 m wide labial palpi ( Fig. 1 C), culminating in three basiconic sensilla (not shown). Labiobase with few 9 m long setaceous sensilla ( Fig. 2 A).

Examined material: Two entire larvae and three head capsules, two analysed with a light microscope and one by scanning electronic microscopy.

Second larval instar

Body: light yellow, measuring 6.5 mm in maximum length and 3.0 mm in width, dorsoventrally compressed and with evident segmentation ( Fig. 2 B). Pleural lobes pronounced, spiracular depressions present. Integument wholly covered with short spines (not shown).

Head capsule: Mainly unpigmented; 2.0 mm long x 1.9 mm in maximum width. Coronal suture continuous with frontal suture ( Fig. 2 C). Antennal orbits very inconspicuous with three sensilla (not shown). A distinct group of 6 punctures on subgenal area; parietal bands indistinguishable; hypostoma, pleurostoma and anterior tentorial arms pigmented, epistoma well defined and also pigmented ( Fig. 2 C).

Mouthparts: Labrum about 500 m wide, with 18–20 punctures ( Fig. 2 C). Spines at middle of epipharynx, directed apically. Maxilla unpigmented, lacking setae. Mandible about 263 m long, bearing 3 teeth and various spine­like denticles; labium unpigmented and very simple, 230 m wide ( Fig. 2 C).

First larval instar

Body: white and cylindrical, 3.0 mm long x 0.8 mm wide, with evident segmentation ( Fig 2 D). Pleural lobes slightly pronounced in thoracic region, spiracles brown (not shown). Body covered with 1–2 μm spines, more densely so at posterior portion and intersegmental areas ( Fig. 2 D—detail).

Head capsule: Mostly unpigmented, except for brown maxillary scleromes, epistoma and pleurostoma. Mouthparts greatly reduced: labrum about 100 m wide with 9–10 punctures, mandible pigmented (172 m long) with 3 teeth, maxilla with no setae; labium unpigmented and very reduced ( Fig. 2 D).

Cocoon

Wall composed of two distinct layers: a silky outer one and a sturdy dark brown internal one. Inner surface shiny black and smooth (not shown). Walls apparently composed of spherical grains embedded in some kind of secreted matrix ( Fig. 2 E).

Egg

White, cylindrical, not curved, with rounded extremities; 2.5 mm length x 0.7 mm width. Micropyle appears as a punctured area on the anterior extremity ( Fig. 2 F).

Figures

FIGURE 1. Last larval instar. 1 A: Body integument and spiracular structure. 1 B: Head surface. Lb—labrum; Ma—mandible; Mx—maxilla; Sp—spinneret. 1 C: Head structure. Mx—Maxilla; black arrow—metopic suture. 1 D: Labrum. Black arrows—basiconic sensilla; white arrows—setae. 1 E: Epipharynx. 1 F: inner maxilla surface and lacinia. Pm—maxillary palpus; La—lacinia; asterisk—basal portion.

FIGURE 2. Spinneret surface and other immature stages. 2 A: Spinneret. White arrow—middle depression of salivary lips. 2 B: Living second larval instar. 2 C: Head structure of second larval instar. White arrow—metopic suture; black arrow—mandible; black asterisk—labrum; white asterisk—labium. 2 D: First instar larva structure and body integument (detail). Black arrowspiracle; black asterisk—mandible. 2 E: Oblique fracture of internal cocoon layer. 2 F: Egg surface and micropyle (detail). Asterisk—anterior extremity.