Larval morphology of three species of Anteoninae (Hymenoptera, Dryinidae) Author Bückle, Christoph text Zootaxa 2017 2017-09-18 4320 3 470 486 journal article 32075 10.11646/zootaxa.4320.3.4 3dd0a46f-3452-4402-af3d-c16a970f507d 1175-5326 893778 2C52Ede7-E218-4334-8991-A7E04F9543F1 Anteon flavicorne ( Dalman, 1818 ) Figs 1–8 Material examined. Italy, Viterbo Province, Gradoli, 4.VI.2004 and 5.VI.2012 , 23 immature and 15 mature larvae parasitizing Rhytidodus decimusquartus (Schrank, 1776) and Macropsis graminea (Fabricius, 1798) (Cicadellidae) feeding on Populus nigra Linnaeus, 1753 . FIGURE 1. Anteon flavicorne (Dalman) . Immature larva. A, B. On nymph of Rhytidodus decimusquartus (Schrank) , in position between meso- and metathorax. C. On nymph of R. decimusquartus , in position between metathorax and abdomen. D. On nymph of Macropsis graminea (Fabricius) , in position between metathorax and abdomen. E. On nymph of M. graminea , in position between meso- and metathorax. F. Lateral view. FIGURE 2. Anteon flavicorne (Dalman) . A, B. Immature larva. A. Anterior region, frontal view. B. Anterior region, lateral view (ap = “ anneau péricéphalique ” sensu Buyckx, 1948).—C. Mature larva, lateral view. Description, immature larva. Body brown ( Fig. 1F ). Larva strongly hooked to the host body. Posterior area of cephalic region attached in the host’s integument, enveloped by a cuticular collar-shaped thickening (“ anneau péricéphalique ” sensu Buyckx, 1948 ; Fig. 2B : ap). Frontal area of cephalic region without cephalic vesicles, completely covered by a “mask” consisting of a layer (tissue?) of sclerotized areas ( Figs 2A, 2B , 7A, 7B ). In particular, it presents a sclerotized transverse area in correspondence to the frontal margin of the future head capsule of the mature larva. Under the “mask”, the immature larva shows the developing mouthparts of the future mature larva ( Figs 3A–3D ), as observed also in larvae of other Dryinidae subfamilies. Body in lateral view ovoid, slightly elongate ( Figs 1F , 3B ), folded U-shaped with its posterior region strongly bent ventrally and strictly placed against its anterior region. Integument strongly puckered (as in Fig. 9B ). Its surface covered by discarded exuviae of previous larval instars. Segmentation of body indistinct, respiratory system peripneustic with nine pairs of lateral spiracles (one thoracic + eight abdominal). Ventral process absent. Remarks. The position of the dryinid larva in the studied hosts is variable ( Figs 1A–1E ). In Rhytidodus decimusquartus immature larvae were observed to protrude from the intersegmental membranes situated between pro- and mesothorax (in two cases), meso- and metathorax (in 18 cases), or metathorax and abdomen (in 11 cases). In Macropsis graminea nymphs, they protruded between the host’s meso- and metathorax (in one case) or metathorax and abdomen (in six cases). Immature larvae were never observed on the abdomen segments of neither of the hosts. Description, mature larva. Body length: ca. 3.1–3.9 mm . Larva apodous, whitish, subcylindrical ( Figs 2C , 4A ). Head yellowish, well sclerotized, without parietal bands and distinct medial ecdysial line posteriorly. Antennal orbit circular, slightly convex, with two sensilla ( Figs 4B, 4C , 6D , 8E ). Chaetotaxy of head capsule characterized on each side by four long sensory bristles situated one medially of antennae, two in proximity of posterior margin of clypeus and one on the side ( Figs 4B, 4C , 7D–7F ). Head capsule with each side possessing one pair of sensory pits between antenna and anterior margin ( Fig. 4C , arrow a, 8F) and one sensory pit in anterolateral position ( Fig. 4C , arrow b, 8G); frontoventral and frontolateral margin of head capsule (near articulation of mandibles and maxillae) strongly sclerotized ( Figs 3C, 3D ). Frontoclypeal suture distinct ( Fig. 4B ). Anterior margin of clypeus concave ( Figs 4B , 5A , 6A , 7D, 7E ). Labrum with an apical row of six to eight sensory bristles inserted immediately under its apical margin, four or five long sensory bristles and two sensory pits at about midlength between anterior and posterior margin ( Figs 4B , 5A , 6A , 7C, 7D , 8A ); basal and lateral margin of labrum distinctly sclerotized. Epipharynx covered by scaly microsculpture, scales anteriorly distinctly pectinate forming slightly curved transverse rows of spinules, and with two sensilla near anterior margin ( Figs 5B , 6A arrows, 7C arrows). Mandible strongly sclerotized with broad base and apical portion pointed and curved in medial direction. Each mandible with long sub-basal sensory bristle ( Figs 5C , 7C–7F ). Maxilla weakly sclerotized, with maxillary palp and five long sensory bristles ( Figs 4C , 5F , 7F ). Maxillary palp ( Figs 5D, 5F , 6C , 7F ) unsegmented, subcylindrical, with large lateral sensory depression and with subapical sensory bristle, apically with delimited area including four sensilla of different size and structure: two uni-articulated cone-shaped and two bi-articulated consisting of a long cylindrical basal and a small cone-shaped apical article. Labium subtriangular distally with narrow spinneret and subapically with labial palps ( Figs 5E, 5F , 6B , 7C , 8B, 8C ). Three long sensory bristles ventrally on basal half of labium ( Figs 5E, 5F , 7C , 8B ). Labial palp ( Figs 5E, 5F , 8B, 8C ) unsegmented, with large proximal sensory depression and with four distal sensilla structurally similar to those of maxillary palp. Spinneret apically opening by transverse slit ( Figs 7C , 8B ), opening with dorsal border distinctly papillose ( Figs 8C, 8D ). Thorax and abdomen with indistinct segmentation and with numerous long sensory bristles (150–200 µm) arranged in transverse rows around each segment ( Figs 2C , 4A , 6H–6K ). Tracheal system with one pair of thoracic spiracles (pro-mesothoracic) and eight pairs of slightly smaller abdominal ones located on the first eight abdominal segments ( Fig. 4A ). Atrium of spiracles bulb-shaped ( Figs 6E–6G ). All spiracles simple, without bristles, hairs or other particular protection structures. FIGURE 3. Anteon flavicorne (Dalman) . Last immature larva instar after “mask” removal. A. Ventral view. B. Lateral view. C. Head, frontal view. D. Head, lateral view. E. Anteon brevicorne (Dalman) (= A. jurineanum Latreille ), lateral view (from Ponomarenko, 1975). hc = head capsule; l = labrum; lb = labium; md = mandible; mx = maxilla. FIGURE 4. Anteon flavicorne (Dalman) . Mature larva. A. Lateral view. B. Head capsule, dorsal view. C. Head, lateral view. FIGURE 5. Anteon flavicorne (Dalman) . Mature larva. A. Labrum. B. Epipharynx. C. Left mandible, dorsal view. D. Left maxillary palp, dorsal view. E. Labium, ventral view. F. Left maxilla and labium, ventral view. FIGURE 6. Anteon flavicorne (Dalman) . Mature larva. A. Epipharynx (arrows: two sensilla). B. Labium, ventral view. C. Left maxilla, dorsal view. D. Antenna. E. Thoracic spiracle and part of trachea, lateral view. F. Exterior margin of thoracic spiracle, from outside. G. Atrium of thoracic spiracle, from outside. H. Rows of setae bases on abdomen. I. Setae on abdomen. K. Setae at caudal end of body. FIGURE 7. Anteon flavicorne (Dalman) . A, B. Immature larva with “mask”. A. Anterior region, frontal view. B. Anterior region, lateral view. C–F. Mature larva, head. C. Frontal view (arrows: two sensilla of the epipharynx). D. Dorsal view. E. Lateral view. F. Ventrofrontal view. FIGURE 8. Anteon flavicorne (Dalman) . Mature larva. A. Labrum, dorsal view. B. Labium, ventral view. C. Labium, ventrofrontal view. D. Dorsal margin of spinneret. E. Antenna. F. Pair of sensory pits between antenna and anterior margin of head capsule. G. Single sensory pit in anterolateral position of head capsule. Remarks. Cocoon in the ground, covered by small soil particles.