Gasteruption phragmiticola Saure, 2006

Bogusch, Petr, van Achterberg, Cornelis, Silhan, Karel, Astapenkova, Alena & Heneberg, Petr, 2018, Description of mature larvae and ecological notes on Gasteruption Latreille (Hymenoptera, Evanioidea, Gasteruptiidae) parasitizing hymenopterans nesting in reed galls, Journal of Hymenoptera Research 65, pp. 1-21 : 11-12

Gasteruption phragmiticola Saure, 2006

Figs 3D , 4G-I (whole larva), 5G-I (drawings of body parts)

Material Examined.

Czech Republic, Bohemia or., Zlíč env., Dubno Natural Reserve , 50.406146, 16.068075, 05.i.2015, 1 larva from the nest of Hylaeus pectoralis , P. Bogusch, A. Astapenková & T. Vavřenová lgt .; Czech Republic, Bohemia bor., Jestřebí env., Novozamecky rybnik National Natural Reserve , 50.622443, 14.556209, 20.ii.2018, 4 larvae from nests of Hylaeus pectoralis ; Bohemia bor., Doksy env., Brehyne-Pecopala National Nature Reserve , 50.574244, 14.693014, 20.ii.2018, 1 larva from nest of Hylaeus pectoralis , P. Bogusch & A. Astapenková lgt .; Bohemia centr., Žehuň env., Zehunsky rybnik National Nature Reserve , 50.151437, 15.304318, 28.i.2017, 2 larvae from nests of Hylaeus pectoralis , P. Bogusch lgt .; Hungary, Pákozd env., Velencei-tó, 20.i.2017, 47.214611, 18.573709, 3 larvae from nests of Hylaeus pectoralis , P. Bogusch lgt., all larvae P. Bogusch det. and coll .

Diagnosis.

The mature larva of G. phragmiticola is similar to other larvae of this genus, with dorsoventrally flattened body, conspicuous lateral tubercles and tridentate mandibles. It is quite big corresponding with its measures with larva of G. nigrescens , of which it differs by creamy or light yellowish color in general (larvae of G. nigrescens are white or whitish in general) and all setae on the body pale (larva of G. nigrescens possesses some of the prominent setae on the head, mouthparts, and last two abdominal tergites brownish or red-brownish). The mature larva possesses also less setae on the frons, and all the setae on the head are smaller and less conspicuous than those of G. nigrescens (and of similar proportions towards the head as in G. assectator ). The mandibles are brownish colored and sclerotized, as well apices of labium and maxilla. It is in contrast with mature larva of G. nigrescens whose end of labrum is light brownish and brownish pigmented are only mandibles and maxillary and labial palpi. All studied larvae are very similar in general appearance and do not differ in the chaetotaxy and morphology.

Description.

Body: Body length 7.3-9.5 mm (N=11). Body vestiture without spicules, consisting only of numerous slender, pale setae, tapering to fine points, arising from small but distinct alveoli; these setae conspicuous and elongate. Setae moderately abundant on elevated dorsal surfaces of thorax and widely scattered on anterior ventral surface of thorax; some setae present on dorsal surfaces of metasomal tergites while tergites 3-7 possess less setae than T1-3 and T8-T10. Caudal annulets of abdominal segment 8, 9, and 10 are most setose; dorsal surface elsewhere with scattered short inconspicuous setae. Body form of postdefecating larva wide and dorsoventrally flattened, robust; body segments similarly wide on whole length (Fig. 4G-H ). Paired body tubercles absent or very ill-developed on thorax but present and well-developed on metasomal segments except last (T10), T7-T9 with less conspicuous tubercles than previous tergites. Dorsal tubercles flat and well-developed on thoracic segments 2 and 3, and abdominal tergites while most conspicuous are on T2-T6. Body shape of predefecating larva in lateral outline with first abdominal segments having greatest diameter and outline tapering slightly forward and strongly backward from there. Abdominal segment 9 shorter and more hirsute than previous, segment 10 attached to middle of segment 9 in lateral view; anus positioned medially and transverse. Spiracles (Figure 5I ) unpigmented, subequal in diameter; atrium globular, slightly wider than deep, projecting little above body wall, with rim; atrial opening diameter vs. peritreme width ratio 1.5; atrial inner surface with rows of wrinkles concentric with primary tracheal opening; primary tracheal opening with collar; subatrium long, with about 30 or more chambers of approximately equal size except one or two next to atrium slightly larger in diameter. Sex characters unknown.

Head: Head moderately small in relation to body size; oriented in normal, hypognathous position relative to thorax. Setae long but sparse on upper part of head capsule; those of maxillary and labial apices large, straight and conspicuous. Head capsule unpigmented except at points of articulations with mandibles; labrum faintly pigmented except transverse labral sclerite slightly darker; mandibles moderately pigmented except mandibular apices and areas of articulation with head capsule strongly pigmented; maxillary sclerites faintly pigmented; salivary lips not projecting, unpigmented; antennal papilla, maxillary and labial palpi all uniformly moderately pigmented (Figs 4I , 5G ). Spiculation apparently absent even on hypopharynx, not on maxilla. Coronal ridge present for more than half distance from postoccipital ridge toward level of antennae in frontal view; postoccipital ridge developed but badly visible, not bending forward; hypostomal ridge well developed, giving rise to pronounced dorsal ramus that extends posteriorly for short distance before ending abruptly in front of postoccipital ridge; both hypostomal ridge and ramus unpigmented; posterior part of ridge bending strongly mesad, forming deeply recessed posterior tentorial pit at junction with posterior tentorial bridge; posterior bridge absent in postdefecating larva because specimen preparing to molt; internal pleurostomal ridge obviously present but not well defined; epistomal ridge not developed. Tentorium mostly absent because of impending ecdysis. Parietal bands absent. In lateral view, clypeus not projecting beyond frons, antenna arising from well-developed prominence, and labrum not extending much beyond clypeus. Diameter of basal ring of antenna about two-thirds distance from closest point on ring to center of anterior tentorial pit; antennal papilla distinctly but not strongly pigmented, moderately large and elongate, longer than twice basal diameter, apically rounded, bearing perhaps two sensilla apically. Frontal area between antennae with two linear rows of four setae and one sensilla ventrally (near clypeus), two additional setae laterally near highest positioned sensillae. Parietal region with several setae - six setae from pleurostomal ridge to front tentorial pit, three smaller setae under antennal orbit, and one conspicuous seta just above basal clypeal margin. Same area between these setae with plenty of small sensillae forming rough structure. Clypeus wide with ill-developed basal and apical margins, two sensillae basally on sides and three small sensillae more medially on each side. Labrum deeply emarginated apically in middle, with a group of four conspicuous and many smaller sensillae on each side apically; labral sclerite not defined and only very poorly pigmented. Epipharynx with rough structure only apically. Mandible moderately robust; darkly pigmented, tridentate with apical tooth longest and sharp, medial tooth with blunt apex, lateral tooth small; cuspal area developed, projecting, with surface irregularly uneven; outer mandibular surface without setae (Figure 5H ). Maxillary apex strongly bent mesad in frontal view, so that maxillary palpus subapical in position; cardo distinct, posterior end directed toward posterior tentorial pit; stipes weakly sclerotized except for conspicuously long stipital rod that is darkly stained by dye, at posterior end articulating with cardo, at anterior end broadening and branching to form weakly pigmented articulating arm of stipes; maxillary palpi elongate, probably more than two times basal diameters, both pigmented like antennal papilla but slightly thinner than papilla. Labium not divided into prementum and postmentum; apex moderately narrow in frontal view; premental sclerite apparently absent as well as border between pre- and postmentum. Two setae on both sides and two smaller on ventral surface. Salivary lips round and well-visible, with inner surface bearing parallel longitudinal grooves; width of lips slightly more than double width of maxillary palpus. Labial palpus scale-like with three sensillae in middle.

Figures

Figure 3. Nests with larvae of Gasteruption. A Larva of Gasteruption nigrescens in nest of Heriades rubicola (Hungary, Szeged, 2017) B Larva of Gasteruption nigrescens in nest of Hoplitis leucomelana (Czech Republic, Novozamecky fish pond, 2018) C Larva of Gasteruption phragmiticola in nest of Hylaeus pectoralis (Czech Republic, Novozamecky fish pond, 2018) D larva of Gasteruption phragmiticola extracted from nest of Hylaeus pectoralis (Czech Republic, Dubno, 2015).

Figure 4. Larvae of Gasteruption. Gasteruption assectator. A mature larva, lateral view B mature larva, dorsal view C head - mouthparts. Gasteruption nigrescens D mature larva, lateral view E mature larva, dorsal view F head - mouthparts. Gasteruption phragmiticola G mature larva, lateral view H mature larva, dorsal view I head - mouthparts.

Figure 5. Body parts of larvae of Gasteruption. Gasteruption assectator. A head, frontal view B mandible, frontal view C spiracle. Gasteruption nigrescens D head, frontal view E mandible, frontal view F spiracle. Gasteruption phragmiticola G head, frontal view H mandible, frontal view I spiracle.