Research Article |
Corresponding author: Elijah J. Talamas ( billy.jenkins@GMAIL.COM ) Academic editor: Matthew Yoder
© 2017 Elijah J. Talamas, István Mikó, Dylan Johnston-Jordan.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Talamas EJ, Mikó I, Johnston-Jordan D (2017) Convergence in the ovipositor system of platygastroid wasps (Hymenoptera). In: Talamas EJ, Buffington ML (Eds) Advances in the Systematics of Platygastroidea. Journal of Hymenoptera Research 56: 263-276. https://doi.org/10.3897/jhr.56.12300
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It is widely accepted that there are two ovipositor system types in Platygastroidea. The Scelio-type ovipositor system features telescoping conjunctiva between metasomal tergites 6 and 7 and operates via internal changes in hydrostatic pressure alone, whereas muscles are involved in ovipositor extension and retraction in the Ceratobaeus-type. We here provide analyses of ovipositor systems in two platygastrine genera that cannot be classified as either Scelio- or Ceratobaeus-type, but exhibit telescoping conjunctivae and extend the ovipositor system without musculature. These represent unique derivations that are clearly identifiable by the location of the telescoping conjunctiva. In Gastrotrypes Brues, the telescoping conjunctiva occurs between T5 and T6, and in Platygaster tubulosa Brues it occurs between each segment from T3 to T6. If there are convergent derivations of a Scelio-type ovipositor system within Scelionidae (sensu
SEM, CLSM, morphology, conjunctiva, parasitoid
The mechanism of ovipositor extension in Platygastroidea is unique among hymenopterans with retracted ovipositors. Outside of Platygastroidea the ovipositor is protracted by the contraction of the 2nd valvifer-2nd valvula muscles and the anterior pivot of the bulb is often accompanied by posterior rotation of the ovipositor (Figure
Gastrotrypes is cosmopolitan in distribution with seven valid species and numerous species that remain undescribed. Individuals are typically small, often less than 1 mm in length, and are known to be associated with gall midges that feed in the vascular tissue of freshly cut wood (
Metanopedias 1 female (OSUC404924), habitus, lateral view 2 female (OSUC265251), habitus, lateral view 3 female (OSUC266113), habitus, lateral 4 female (USNMENT00989611_2), metasoma, lateral view 5 female (USNMENT00989611_2), T5, S5, lateral view. Scale bars in millimeters.
Platygaster tubulosa is recognizable by the presence of only two external tergites when the ovipositor system is retracted. Like Gastrotrypes, it is associated with Cecidomyiidae that feed in wood vascular tissue (
Dissections for scanning electron microscopy were performed with a minuten probe and forceps and body parts were mounted to a 12 mm slotted aluminum mounting stub (EMS Cat. #75220) using a carbon adhesive tab (EMS Cat. #77825-12) and sputter coated with approximately 70 nm of gold/palladium using a Cressington®™ 108 sputter coater. Micrographs were captured using a Hitachi®™ TM3000 Tabletop Microscope at 15 keV. Sample preparation for CLSM followed
The numbers prefixed with “USNMENT” or “OSUC ” are unique identifiers for the individual specimens (note the blank space after some acronyms). Details on the data associated with these specimens may be accessed at the following link: purl.oclc.org/NET/hymenoptera/hol, by entering the identifier in the form (e.g. “OSUC123123”)
We apply the terminology from
1vf first valvifer (Figure
2vf second valvifer (Figure
3vv third valvula (ovipositor sheaths, Figures
ac acanthae (Figures
c cercus (Figures
cj T5–T6 conjunctiva between T5 and T6 (Figures
il inflection line of telescoping conjunctiva (Figures
lt3–lt5 metasomal laterotergites 3–5 (Figure
T1–T9 metasomal tergites 1–9 (Figures
trb terebra (1st and 2nd valvulae, Figure
S1–S6 metasoma sternites 1–6 (Figures
The ovipositor system in Gastrotrypes is functionally identical to the Scelio-type in that it possesses elongate, telescoping conjunctiva and distal metasomal segments are protracted with the ovipositor. It differs in that elongation of the conjunctiva occurs between T5 and T6 (Figures
Gastrotrypes 6 female (USNMENT01109431), habitus, lateral view 7 female (
Gastrotrypes 9 female (USNMENT01081081), ovipositor system, ventral??? view 10 female (USNMENT01109429), ovipositor system, lateral view 11 female (USNMENT01059434), ovipositor system, dorsal view 12 female (USNMENT01109445), ovipositor system, dorsolateral view 13 female (USNMENT01109665), ovipositor system, ventral view 14 conjunctiva, lateral view. Scale bars in microns.
The conjunctiva between T5 and T6 in Gastrotrypes features acanthae where it attaches to the posterior margin of T6 and a second ring of acanthae anterior to its distal inflection site (Figures
Similar acanthae types were found on the internal surface of the third valvula in other Hymenoptera (
Gastrotrypes sp. female (USNMENT01197222). CLSM volume rendered maximum intensity projection micrograph showing the ovipositor system and distoventral metasomal tergites. Scale bar in microns.
The presence of telescoping conjunctiva between each of metasomal segments 3–6 (Figures
As in Gastrotrypes, the conjunctiva is striate and T6 is immovably attached to T7+8 (Figure
Gastrotrypes female (USNMENT01197222). CLSM of metasoma and retracted ovipositor system, ventral view. Scale bar in microns.
Platygaster tubulosa, female (USNMENT01109983) 22 head, mesosoma, metasoma, lateral view 23 habitus, dorsal view. Scale bars in millimeters.
Platygaster tubulosa, female (USNMENT01109983) 24 ovipositor system, including metasomal segments 25T2–T3, dorsolateral view; T4, S4, ventrolateral view 26T5–S5, ventral view 27T6–T8, lateral view. Scale bars in microns.
Platygaster tubulosa, female (USNMENT01109983) 28T6–T8, dorsal view 29T6–T8, ventral view. Scale bars in microns.
30 Paridris coorgensis, female (USNMENT01223722B), acanthae on conjunctiva, lateral view 31 Calliscelio rubriclavus, female (USNMENT01109461), acanthae on conjunctiva, lateral view 32 Calliscelio rubriclavus, female (USNMENT01109461), apex of extended ovipositor system, lateral view 33 Paridris coorgensis, female (USNMENT01223722B), T6–T8, lateral view 34 Probaryconus, female (USNMENT01223862), T6–T8, lateral view 35 Archaeoteleia mellea, female (
We treat the telescoping ovipositor systems in Gastrotrypes and Platygaster tubulosa as independent derivations based on multiple lines of evidence: the plesiomorphic condition for Platygastridaes.s. is a Ceratabaeous-type ovipositor (
Identification of convergence will ultimately be determined by morphological analysis and the phylogenetic placement of Archaeoteleia relative to the main scelionid clade, a task challenged by what appears to be a significant age difference between these lineages. Archaeoteleia has existed for at least 99 Mya based on a specimen in Burmese amber (Talamas et al. 2017), whereas the oldest reliable fossil of a Scelio-type ovipositor from the main scelionid clade has an age of ~45 Mya (
EJT: project conception, photography, electron microscopy, manuscript preparation, character analysis; IM: confocal laser scanning microscopy, character analysis, manuscript preparation; DJ-J: scanning electron microscopy.
We are grateful to Lubomir Masner (
URI table of HAO morphological terms
Data type: Microsoft Excel Spreadsheet (.xlsx)
Explanation note: This table lists the morphological terms used in this publication and their associated concepts in the Hymenoptera Anatomy Ontology.