Sycophila Walker 1871

Gómez, J. F., Nieves-Aldrey, J. L. & Stone, G. N., 2013, On the morphology of the terminal-instar larvae of some European species of Sycophila (Hymenoptera: Eurytomidae) parasitoids of gall wasps (Hymenoptera: Cynipidae), Journal of Natural History 47 (47 - 48), pp. 2937-2960 : 2941-2949

Sycophila Walker 1871

Description

Body in ventral view varying from fusiform to barrel-shaped formed by head, three thoracic segments (THS) and nine abdominal segments (ABS) with one anal segment (ANS) ( Figures 1 and 4 ); the ratio L/W usually varying from 1.7 to 2.1; in lateral view ( Figures 2 and 5 ) body with ventral margin of abdominal body segments straight or slightly convex in profile in almost all species; anterodorsal protuberances (adp) as intersegmental membranes sometimes protruding; spiracles (epc) present from THS3 to ABS7; colour whitish; integument generally smooth; body mostly glabrous, with some short setae visible on thoracic segments.

Head in anterior view ( Figures 3A and 6 ) oval or trapezoid, with protruding mouthparts; head 1.1–1.3 times as broad as high; medial area of vertex not incised and with margin mostly straight or slightly concave. The head shows the basic chaetotaxy pattern found in larvae of the examined Chalcidoidea (excepting Eurytoma ), comprising not more than five clearly visible pairs of setae: vams, anteromedial setae of vertex; ams, anteromedial setae of antennal area; cs, clypeal setae; gns, genal setae and hs, hypostomal setae. Vertex with one pair of relatively short erect setae (vams) usually situated midway between anterior margin of vertex and the antennae; ams situated approximately at the same level as the antennae; antennal area (anr) indistinct; antennae (an) short, button-like, situated more or less in the middle of the head; cs situated laterally above the level of ventral margin of clypeus (cl); ventral margin of clypeus straight.

Mouth parts ( Figures 3B and 7 ) with labrum (lb) subrectangular, divided into two lateral flaps (lfp) or lobes and one medial part (lmp), with the latter subdivided into five lobes; divisions of medial part of labrum usually deep, almost reaching the level of labral setae, forming five clearly differentiated lobes of equal size; maxillae (mx) well differentiated from labium; maxillary and labial palps inconspicuous; mandibles ( Figure 8 ) with the apical tooth generally visible or exposed in part, with at least the tip visible; two teeth in each mandible; first tooth long and slender, with ratio L/W 1T between 2.0–2.9; outer margin of first tooth strongly convex; tip moderately or strongly recurved; apex of the second tooth straight, directed upwards in the same direction as the first tooth and being acute or blunt; direction of the apex of the second tooth usually straight with the inner margin not interrupted.

Monophyly and recognition

The genus Sycophila Walker 1871 is a cosmopolitan genus currently containing 114 described species ( Noyes 2012). Bouček (1974) synonymized Eudecatoma Ashmead , the old name for the Holarctic species, with Sycophila Walker , which formerly included mainly Indo-Malayan species. Though accepted by most workers, this synonymization was not accepted by Zerova (1988 / 1996), who has kept the two genera taxonomically separated. Sycophila (= Eudecatoma ) is a distinctive genus that according to Claridge (1961) forms a clearly distinct natural group within the Eurytomidae . It is easily distinguished from Eurytoma on the basis of adult morphology ( Claridge, 1959 – 1961). Following recent phylogenetic work based on morphological characters (Lotfalizadeh et al. 2007), diagnostic features of adult Sycophila are a clypeus bilobed, a lateral foramina plate with the dorsal margin forming, together with the inner edge of postgenal grooves, a strongly wavy line; the postgenal grooves somewhat curved in their upper parts; metatibia with dorsal enlarged setae; thickened marginal vein; forewing with a more or less broadly infumated spot behind the marginal vein and the lack of a pronounced difference between antennae of the sexes, regardless of the number of antennal segments. The characteristic morphology of Sycophila larvae relative to other eurytomid genera has been mentioned by Claridge (1959) for S. submutica , by Henneicke et al. (1992) and Redfern and Askew (1992) for S. mellea .

Our results show the main diagnostic features of the Sycophila larvae studied here to be the considerable reduction in number and length of body setae; the relative position of head setae, the clypeus and shape of labrum; the maxillae well differentiated from the labium and the relatively small size of the mandible tooth.

Biology

Tropical species of Sycophila are either parasitoids associated with endophytophagous hosts, in habitats such as figs (as their name suggests), phytophagous hosts, and also inquilines consuming plant tissues ( Bouček 1988). Many are associated with plant galls and the majority of the European species attack galls of Cynipidae ( Claridge 1959; Askew 1961; Nieves-Aldrey 1984; Schönrogge et al. 1995, 1996a, 1996b; Askew et al. 2006; Gómez et al. 2006; Lotfalizadeh et al. 2008). As far as is known, European Sycophila parasitoids of gall wasps are koinobiont endoparasitoids ( Askew and Shaw 1986), a behaviour that is rare in the family Eurytomidae ( Claridge 1961) , and the reduction in setae shown by their larvae may be associated with its life history ( Claridge 1959).

Figures

Figure 1. Body in ventral view of Sycophila submutica (Thomson). Letters refer to the following structures: ABS1–ABS9, abdominal segments; ANS, anal segment; THS1–THS3, thoracic segments.

Figure 2. Body in lateral view of Sycophila submutica (Thomson). Letters refer to the following structures: ABS1–ABS9, abdominal segments; ANS, anal segment; THS1–THS3, thoracic segments; adp, anterodorsal protuberances; epc, spiracles.

Figure 3. Illustrations of the terminology used for general descriptions in different views. (A) Anterior view of head of Sycophila mayri (Erdos), letters refer as follows to the described structures: ams, anteromedial setae of antennal region; an, antenna; anr, antennal area; cl, clypeus; cs, clypeal setae; fr, frons; gns, genal setae; gr, genal region; hr, hypostomal region; hs, hypostomal setae; lb, labrum; lbi, labium; md, mandible; mx, maxillae; vams, anteromedial setae of vertex; vr, vertex region. (B) Anterior view of mouthparts of Sycophila biguttata (Swederus), showing the clypeus (cl); clypeal setae (cs); labrum (lb); labral setae (lbs); lateral lobes of labrum (lfp): medial piece of labrum (lmp) and the lower-lip complex: labium (lbi); mandible (md); maxillae (mx). (C) Anterior view of the right mandible of Sycophila binotata (Fonscolombe), showing the first and second tooth and the base (mbs).

Figure 4. Ventral views of terminal-instar larvae. (A) Sycophila biguttata; (B) Sycophila binotata; (C) Sycophila flavicollis; (D) Sycophila mayri; (E) Sycophila submutica ex Isocolus scabiosae form rogenhoferi; (F) Sycophila submutica ex Isocolus lichtensteini.

Figure 5. Lateral views of terminal-instar larvae. (A) Sycophila biguttata; (B) Sycophila binotata; (C) Sycophila flavicollis; (D) Sycophila mayri; (E) Sycophila submutica ex Isocolus scabiosae form rogenhoferi

Figure 6. Anterior view of the head of terminal-instar larvae. (A) Sycophila biguttata; (B) Sycophila binotata; (C) Sycophila flavicollis; (D) Sycophila mayri; (E) Sycophila submutica ex Isocolus. scabiosae form rogenhoferi; (F). Sycophila submutica ex Isocolus lichtensteini.

Figure 7. Anterior view of mouthparts of terminal-instar larvae. (A) Sycophila biguttata; (B) Sycophila binotata; (C) Sycophila flavicollis; (D) Sycophila mayri; (E) Sycophila submutica ex Isocolus scabiosae form rogenhoferi.; (F) Sycophila submutica ex Isocolus lichtensteini.

Figure 8. Anterior view of the right mandible of terminal-instar larvae. (A) Sycophila biguttata; (B) Sycophila binotata; (C). Sycophila flavicollis; (D) Sycophila mayri; (E) Sycophila submutica ex Isocolus scabiosae (k) form rogenhoferi (k).