Research Article |
Corresponding author: Benjamin Eggs ( benjamin.eggs@protonmail.ch ) Academic editor: Michael Ohl
© 2022 Massimo Olmi, Benjamin Eggs, Leonardo Capradossi, Thomas van de Kamp, Evgeny E. Perkovsky, Adalgisa Guglielmino, Dmitry V. Vasilenko.
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:
Olmi M, Eggs B, Capradossi L, van de Kamp T, Perkovsky EE, Guglielmino A, Vasilenko DV (2022) A new species of Bocchus from upper Eocene Rovno amber (Hymenoptera, Dryinidae). Journal of Hymenoptera Research 92: 257-271. https://doi.org/10.3897/jhr.92.87084
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A new fossil species of Dryinidae (Hymenoptera, Chrysidoidea) from upper Eocene Rovno amber (Ukraine) is described: Bocchus rex sp. nov. It is compared with two other species of Bocchus known from European amber: B. primaevus Martins & Melo from Baltic amber and B. schmalhauseni Perkovsky, Olmi, Vasilenko, Capradossi & Guglielmino from Rovno amber. A new key to the Cretaceous and Paleogene species of Bocchus is presented. The Dryininae are the most common representatives in all the amber dryinid faunas since the mid-Cretaceous. The Rovno amber fauna is an exception; possible explanations for the abundance of Bocchus species within this amber are presented.
Bocchinae, Bocchus rex, Chrysidoidea, key, systematics
Dryinidae (Hymenoptera, Chrysidoidea) are parasitoids of Auchenorrhyncha (Hemiptera) (
Eighty fossil species of Dryinidae have been described, among which the following six have been recorded from upper Eocene Rovno amber (Ukraine; 35–38 Ma) (
Recently, we received two pieces of Rovno amber: one from a site in the Volyn region adjacent to the Varash district and the second most probably from the Varash district. They included specimens of Dryinidae that proved to belong to a new species, which we describe below.
The description follows the morphological terminology of
The term “disc of metapectal-propodeal complex” is used here in the sense of
The term “ADOs” (= Antennal Dorsal Organs) is used here in the sense of
The specimens studied in this paper have been deposited in the following collections:
Specimen 1: Schmalhausen Institute of Zoology (
Specimen 2:State Museum of Natural History Stuttgart (
The multifocal photos were taken using a mirrorless Sony Alpha 6100 camera (Sony Group Corporation, Tokyo, Japan), with Canon bellows and three-way revolver for optical microscopy (Canon Inc., Tokyo, Japan). The following objectives were used: LOMO 3.7 × 0.11 (LOMO, St. Petersburg, Russia) for magnifications from 20 to 50×; Zeiss Semiplan 6.3 × 0.11 (Carl Zeiss GmbH, Jena, Germany) for magnifications from 50 to 100×. The motorized focus was managed by a Cognisys stackshot controller (Cognisys Inc., Traverse City, MI, USA). Captured images were merged into a single in-focus image by using ZereneStackerTM version 1.04 (Zerene Systems LLC, Richland, WA, USA). Images were processed with GIMP version 2.10.30 (https://www.gimp.org).
Synchrotron X-ray microtomography (SR-µCT) (
The two resulting tomograms were registered and calibrated with Fiji (
Holotype
(= specimen 1; Fig.
Macropterous female of Bocchus (Figs
(Figs
Segmented 3D model of Bocchus rex sp. nov., female, paratype (= specimen 2) based on SR-µCT data (perspective view; cf. Suppl. material
Male. Unknown.
Hosts. Unknown.
Bocchus was the name of two kings of Mauretania (the first being father-in-law to the Numidian King Jugurtha) and rex is an appropriate epithet of this nice species with its regal look.
(= specimen 2). The head and thorax are well preserved but each have a fissure dorsally (Fig.
After the description of Bocchus rex sp. nov., the key published by
Female:
1 | Petiole very short, almost absent (cf. fig. 4 of |
B. cenomanianus Olmi, Rasnitsyn & Guglielmino |
– | Petiole distinctly visible, one sixth to one ninth of rest of metasoma (cf. fig. 1 of |
2 |
2 | Enlarged claw with teeth present only in the distal half of the inner margin (Fig. |
B. schmalhauseni Perkovsky, Olmi, Vasilenko, Capradossi & Guglielmino |
– | Enlarged claw with teeth distributed along the entire inner margin (Figs |
3 |
3 | Head with OOL about 62% of OPL; notauli complete, posteriorly separated (cf. fig. 9 of |
B. primaevus Martins & Melo |
– | Head with OOL about 77% of OPL (Fig. |
B. rex sp. nov. |
Male:
Unknown.
The above-described new species is attributed to the genus Bocchus (Hymenoptera, Dryinidae, Bocchinae) because of the following characters: ocelli present; epicnemium concealed; protarsus chelate; chela with rudimentary claw.
The genus Bocchus includes 103 species present in all zoogeographical regions, except for Antarctica (
Fossil species of Bocchus are known from the Cenozoic (i.e. from Baltic and Rovno amber) as follows: B. primaevus Martins & Melo, 2019 (2021) from upper Eocene Baltic amber, Priabonian, 35–38 Ma; B. schmalhauseni Perkovsky, Olmi, Vasilenko, Capradossi & Guglielmino, 2020 and B. rex sp. nov. from Rovno amber, coeval of Baltic amber. Probably the hosts of the above three species were Tropiduchidae, as they are known from both Baltic and Rovno amber (
A fourth species has been attributed to the genus Bocchus: B. cenomanianus Olmi, Rasnitsyn & Guglielmino, 2010. It is a compression fossil in extremely bad condition from Obeschchayushchiy, Magadan region, Russian Federation (Santonian-Campanian, Upper Cretaceous, 72–85 Ma). However, its attribution to Bocchus is doubtful, because Caliscelidae and Tropiduchidae are not known from the Cretaceous (
The new Bocchus described here is the first hymenopteran and seventh named fossil arthropod from the Volyn Region, Ukraine (
To date, Bocchus is the most common genus of Dryinidae in Rovno amber fauna and Bocchinae is the dominant subfamily (44.4% of specimens versus 33.3% for Dryinus and Dryininae) at the specimen level. This is unusual, as Dryininae strongly dominate not only in Baltic amber, but also in Kachin (33 Dryininae species according to
The biology of Bocchus species is poorly known so far. The species with known biology live in open environments. An even more important reason for the abundance of Bocchus is that open environments were more common in the Priabonian Ukraine than in the Baltic amber forest (
A comparison with the extant Bocchus species shows that their body shape is similar to the species known from European Eocene amber. The chela of B. rex and B. schmalhauseni follows the same general scheme as in the extant species. The only difference can be observed in the chela of B. primaevus and is attributable to the anomalous long and slender protarsomere 5 (Fig.
Schematic drawings of chelae of species of Bocchus known from amber a Bocchus rex sp. nov. b B. primaevus Martins & Melo (from
We are grateful to Nikolai R. Khomich (Rovno, Ukraine) and Jonas Damzen (Vilnius, Lithuania) for their help in obtaining the specimens studied in this paper, to Anatoly P. Vlaskin (
Video S1
Data type: video file (mp4)
Explanation note: Animation of the rotating segmented 3D model of Bocchus rex sp. nov., female, paratype (= specimen 2) based on SR-µCT data (perspective view; cf. Fig.