Gonatopus baeticus ( Ceballos, 1927 )

Guglielmino, Adalgisa, Parise, Gianluca & Bückle, Christoph, 2015, Description of larval instars of Dryinus tarraconensis Marshall, 1868 and Gonatopus baeticus (Ceballos, 1927) (Hymenoptera: Chrysidoidea: Dryinidae), parasitoids of the genus Dictyophara Germar (Hemiptera: Auchenorrhyncha: Dictyopharidae), Zootaxa 4032 (1), pp. 42-54 : 48-52

2. Gonatopus baeticus ( Ceballos, 1927)

( Figs 6–9 )

C. Last immature larval instar ( Figs 6 , 7 A). Maximal width: ca. 1.5 mm.

The external morphology of the immature larvae of Gonatopus baeticus is similar to other Gonatopodinae larvae, in particular to those without a ventral tubercle (e.g. G. lunatus Klug, 1810 : Guglielmino & Virla, 1998; G. chilensis ( Olmi, 1991) : Virla & Mangione, 2000; G. bonaerensis Virla, 1997 : Mangione & Virla, 2004). Cephalic vesicles kidney-shaped, well developed, touching each other at their base ( Fig. 6 ).

Position of the insertion of the larva in the host apparently as in Dryinus tarraconensis .

D. Mature larva ( Figs 7 B–E, 8 , 9). Length: ca. 6 mm; width of head: 0.75 mm.

Larva apodous, white yellowish, subcylindrical. Head brown-yellowish, well sclerotized, without parietal bands and without distinct medial ecdysial line posteriorly. Antennal orbit circular, slightly convex, with two sensilla ( Figs 7 B, 8E ). Chaetotaxy of head capsule characterized on each side by four or five sensory bristles situated between antennae, in proximity of posterior margin of clypeus and base of mandible ( Fig. 7 B). Head capsule ( Figs 7 B, 8A ) with medially one pair of sensory pits, on each side one pair of sensory pits between antenna and anterior margin and one pair of sensory pits in anterolateral position ( Fig. 7 B, arrow). Frontoclypeal suture indistinct. Anterior margin of clypeus straight. Labrum large, anterior angles rounded, dorsal surface with a basal row of six-seven sensory pits and numerous long sensory bristles irregularly distributed until the anterior margin ( Figs 7 C, 8B ). Epipharynx apparently without basal lobe, anterior area with numerous lying thin hairlike setae and with four sensilla proximally of this area; posterior area not pubescent, but covered by scaly microsculpture, scales anteriorly distinctly pectinate forming slightly curved transverse rows of spinules ( Fig. 8C ). Mandible strongly sclerotized, triangular, with broad base and apical portion pointed and curved in medial direction. Each mandible with long sub-basal sensory bristle ( Figs 7 D, 9B). Maxilla weakly sclerotized, with maxillary palp and five long sensory bristles ( Fig. 7 E). Maxillary palp ( Figs 7 E, 8F , 9A, 9C) unsegmented, subcylindric, with large lateral sensory depression ( Fig. 9 D) and with subapical sensory bristle, apically with delimited area including four sensilla of different size and structure: two uni-articulated, small and cone-shaped and two bi-articulated consisting of a long cylindrical basal and a small cone-shaped apical article. Labium sclerotized, distally with spinneret and subapically with labial palps ( Figs 7 E, 8D , 9A). Three sensory bristles in semicircle in proximity of base of each palp. Labial palp ( Figs 7 E, 8D , 9E) unsegmented, with large proximal sensory depression ( Fig. 9 F) and with four distal sensilla structurally similar to those of maxillary palp. Spinneret with two sensory pits on each side ( Figs 7 E, 8D , arrows), apically opening by transverse slit.

Thorax and abdomen with indistinct segmentation. Thorax with small sensory bristles in proximity of the posterior margin of the head capsule and a few longer ones (ca. 40–50 µm) on the rest of the thoracic segments. Abdomen with numerous small sensory bristles (ca. 10–15 µm) arranged in transverse rows around each segment. Tracheal system with one pair of large thoracic spiracles (pro-mesothoracic) ( Figs 8G, 8H ) and eight pairs of smaller abdominal ones located on the first eight abdominal segments. Atrium of thoracic spiracles formed only by few (3–4) cells, all of them reaching exterior margin ( Figs 8G, 8H ). All spiracles simple, without bristles, hairs or other particular protection structures.

Figures

FIGURE 6. Gonatopus baeticus (Ceballos), immature larva. A. Lateral view. B. Anterior region with cephalic vesicles, frontal view.

FIGURE 7. Gonatopus baeticus (Ceballos). A. Immature larva, lateral view. Mature larva: B. Head, dorsal view. C. Labrum, dorsal view. D. Right mandible, ventral view. E. Right maxilla and labium, ventral view.

FIGURE 8. Gonatopus baeticus (Ceballos), mature larva. A. Head, dorsal view. B. Labrum. C. Sensilla of epipharynx. D. Labium, ventral view. E. Antenna. F. Right maxillary palp, ventral view. G. Thoracic spiracle, from outside. H. Thoracic spiracle, lateral view.

FIGURE 9. Gonatopus baeticus (Ceballos), mature larva. A. Maxillae and labium, ventral view. B. Left mandible, ventral view. C. Right maxillary palp, dorsolateral view. D. Detail of Figure C: Large lateral sensory depression. E. Right labial palp, medioventral view. F. Large lateral sensory depression of right labial palp.