Research Article |
Corresponding author: Sergey A. Belokobylskij ( doryctes@gmail.com ) Academic editor: Jovana M. Jasso-Martínez
© 2024 Sergey A. Belokobylskij, Dmitry V. Vasilenko, Evgeny E. Perkovsky.
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:
Belokobylskij SA, Vasilenko DV, Perkovsky EE (2024) The first reliable fossil record of the tribe Centistini (Hymenoptera, Braconidae, Euphorinae): a new subgenus and species of braconid wasp in Danish amber. Journal of Hymenoptera Research 97: 15-27. https://doi.org/10.3897/jhr.97.115789
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A new subgenus and species of the braconid parasitoid of the tribe Centistini s. l. (Euphorinae), Centistoides (Palaeoides) magnioculus Belokobylskij, subgen. et sp. nov., from late Eocene Danish amber are described and illustrated from one female. This is the first time the tribe of euphorine parasitoids is reliably documented in the fossil record. A key to all genera and subgenera of this suprageneric taxonomic group is compiled. The discussion about position of the genus Parasyrrhizus Brues, composition of the tribe Centistini s. l., and the composition of the Danish amber hymenopteran fauna are provided.
Asiacentistes, Centistoides, description, Eocene, ovipositor, subgenus, venation
The extant members of the euphorine tribe Centistini include two genera with a mediocubital vein (M+CU1) of the fore wing that is distinctly desclerotised, namely Allurus Foerster, 1863 and Centistes Haliday, 1835 (with five subgenera: Anartionyx van Achterberg, 1985, Ancylocentrus Foerster, 1863, Centistes s. str., Chaetocentistes Belokobylskij, 2000, and Syrrhizus Foerster, 1863). In addition, two morphologically very similar genera but with a distinctly sclerotised mediocubital vein (M+CU1) of the fore wing, Asiacentistes Belokobylskij, 1995 and Centistoides van Achterberg, 1992, were also attributed to this tribe (
The Centistini species are known as imagobionts (
In this paper the first member (female) of the tribe Centistini sensu lato found in the fossil record is described and illustrated from a specimen in Danish amber.
Priabonian Danish amber of late Eocene age (34–37 Mya) was reviewed by
The braconid specimens were examined with an Olympus SZ51 stereomicroscope. Photographs were obtained using a Leica Z16 APO stereomicroscope equipped with a Leica DFC 450 camera and processed with LAS Core.
The terminology employed for morphological features and sculpture, as well as body measurements, follow
The material used for this study is deposited in the collection of the Natural History Museum of Denmark (NHMD). The holotype inclusion is located in a thin, nearly rectangular piece of amber measuring 8.0 × 6.5 mm.
Class Insecta Linnaeus, 1758
Order Hymenoptera Linnaeus, 1758
Family Braconidae Nees, 1811
Subfamily Euphorinae Foerster, 1863
Tribe Centistini Čapek, 1970
1 | Mediocubital vein (M+CU1) of fore wing distinctly sclerotised and pigmented | 2 |
– | Mediocubital vein (M+CU1) of fore wing unsclerotised and transparent | 3 |
2 | Malar groove present, but sometimes incomplete. Apical segment of antenna without distal spine. Laterope of first metasomal tergite very shallow and small. Dorsal valve of ovipositor apically with wide and finely aciculate lobe. Ovipositor sheath thick and short (posterior view), very densely setose apically. Hind tibia with distinct small sparse spines at its external side | Asiacentistes Belokobylskij, 1995 |
– | Malar groove and suture absent. Apical segment of antenna with distal spine. Laterope of first metasomal tergite rather deep. Dorsal valve of ovipositor apically without lobe. Ovipositor sheath thin and elongate (posterior view), glabrous or relatively sparsely setose apically. Hind tibia without spines at external sides | Centistoides van Achterberg, 1992 |
3 | Claw splitting apically. Hind coxa with distinct acuminated ventro-posterior projection. Metasomal sternites often medially with double teeth | Allurus Foerster, 1863 |
– | Claw not splitting apically, simple. Hind coxa always without ventro-posterior projection. Metasomal sternites medially usually without teeth (Centistes Haliday, 1835) | 4 |
4 | First abscissa of medial vein (1-SR+M) of fore wing absent; discoidal (discal) and second radiomedial (submarginal) cells fused. – Notauli always absent | Centistes (subgenus Syrrhizus Foerster, 1863) |
– | First abscissa of medial vein (1-SR+M) of fore wing present; discoidal (discal) and second radiomedial (submarginal) cells separated | 5 |
5 | Fore coxa on posterior (inner) side in very dense and short brush-like setae. Ovipositor sheaths thick and widened distally (dorsal and lateral views). Apex of ovipositor narrow and sinuated. Hypopygium and two posterior sternites of metasoma in very dense and short setae | Centistes (subgenus Chaetocentistes Belokobylskij, 2000) |
– | Fore coxa on posterior (inner) side without brush-like setae. Ovipositor sheaths rather flat and usually parallel-sided or narrowed distally (dorsal and lateral views). Apex of ovipositor rather wide and straight. Hypopygium and two posterior sternites of metasoma with usual and rather sparse setae | 6 |
6 | Mesoscutum completely without notauli | Centistes (subgenus Centistes s. str.) |
– | Mesoscutum usually with rather distinct and complete notauli; however, sometimes notauli shallow and weakly visible; rarely notauli mainly absent anteriorly, but mesoscutum always with distinct medioposterior elongate or subround pit | 7 |
7 | Inner claw of hind leg much larger than claw of fore leg (especially in female), hooked and larger than outer claw. Second abscissa of mediocubital vein (1-M) of hind wing shorter than basal vein (1 r-m). Ovipositor sheath widened submedially | Centistes (subgenus Anartionyx van Achterberg, 1985) |
– | Inner claw of hind leg only slightly larger than claw of fore leg, subequal to its inner claw. Second abscissa of mediocubital vein (1-M) of hind wing subequal to basal vein (1 r-m). Ovipositor sheath often with subparallel-sided or evenly narrowed distally | Centistes (subgenus Ancylocentrus Foerster, 1863) |
Centistoides doesburgi van Achterberg, 1992, by monotypy and original designation.
This small Madagascan-Neotropical genus includes two extant species, Centistoides doesburgi van Achterberg, 1992 from Suriname (
The Eastern Palaearctic genus Asiacentistes Belokobylskij also has two extant species, A. alekseevi (Belokobylskij, 1992) and A. sinicus Chen & Belokobylskij, 2001 (
Documented here the first reliable fossil member of the tribe Centistini s. l. is found in Danish amber, and it possesses a distinctly sclerotised mediocubital vein (M+CU1) of the fore wing. On the basis of all visible characters of this amber inclusion (for example, malar suture absent, apical antennal segment with distinct distal spine, ovipositor apically without lobe, ovipositor sheath thin and elongate in posterior view, sparsely setose apically) it was placed in the genus Centistoides; however, this specimen has some features that necessitated a separate subgenus for it within Centistoides.
A short redescription of the genus Centistoides and descriptions of the new subgenus as well as the new fossil species are given below.
Occipital carina absent dorsally, only developed on lateral and ventral parts of temple, joining hypostomal carina above base of mandible. Ocelli distinctly enlarged. Eye large. Malar suture absent, but sometimes present short malar groove. Mandible strongly twisted apically. Palpi short, maxillary palpus 3–5-segmented, labial palpus 1–2-segmented. Antenna weakly setiform, apical segment of antenna with distinct distal spine. Mesosoma short and high. Notauli completely absent. Prescutellar depression usually entirely smooth or weakly rugulose, without or only with medial carina. Prepectal carina complete. Mesopleuron mainly smooth; precoxal sulcus absent. Metapleural flange absent or very short. Propodeum without or with weak areolation, with incomplete or complete posterior areola. Radial (marginal) cell of fore wing distinctly shortened. Discoidal (discal) cell usually sessile; petiole (1-SR) absent. First abscissa of medial vein (1-SR+M) of fore wing present. Recurrent vein (m-cu) antefurcal. Mediocubital vein (M+CUl) entirely sclerotized and pigmented. In hind wing, second abscissa of mediocubital vein (1-M) much shorter than first abscissa (M+CU) and shorter than basal vein (r-m). Hind coxa large and subround. Fore femur usually more robust than hind femur. Tarsal claws robust, distinctly curved apically, simple. First metasomal tergite wide and short, almost parallel-sided or weakly narrowed behind spiracles, smooth, without dorsope. Second metasomal tergite smooth; second suture usually absent. Ovipositor strongly compressed, strongly curved and without armament and ventral lobe apically. Ovipositor sheath short, wide, flattened, truncate apically.
Centistoides (Palaeoides) magnioculus sp. nov., by present designation.
Named after “Palaeo” (Greek for “ancient”) and part of the generic name Centistoides from the tribe Centistini.
Ocelli less distinctly enlarged (Fig.
Centistoides (Palaeoides) magnioculus sp. nov. (female, holotype, Danish amber, NHMD # 115540) A habitus, right dorso-lateral view B habitus, dorsal view C head and mesosoma, dorsal view D head and anterior part of mesosoma, dorso-lateral view E head, fronto-lateral view F metasoma and ovipositor, lateral view.
The genus Centistoides (as well as Asiacentistes) characterised by the fore wing mediocubital vein (M+CU1) distinctly sclerotised and pigmented, when such a vein in most Centistini genera is clearly desclerotised and transparent (spectral). Both known Centistoides species, C. doesburgi van Achterberg, 1992 and C. ophthalmicus (Granger, 1949), together with the genus Asiacentistes, have a sessile or subsessile discoidal (discal) cell in the fore wing (
Holotype : female, NHMD # 115540, with labels “Braconidae A.K. Andersen 28-3 /1968” and “Euphorinae ? huge ovipositor”. Danish amber, late Eocene. Syninclusion: female of Chironomidae.
Female. Body length 3.8 mm; fore wing length 3.6 mm.
Head : Head rather short; occiput distinctly concave. Eye large, glabrous, ~ 1.4 times as high as broad (sublateral view); transverse diameter of eye almost 2.0 times longer than temple (subdorsal view). Ocelli medium-sized, convex, situated almost in equilateral triangle; POL approximately 0.8 times Od, 2.0 times OOL; Od ~ 2.2 times OOL. Face weakly convex, its width ~ 0.8 times mid-height. Clypeus distinctly convex, its width ~ 2.0 times mid-height, 0.8 times width of face. Malar space ~ 0.15 times height of eye, ~ 0.7 times basal width of mandible. Malar suture absent. Mandible distinctly twisted in apical half, with two apical teeth.
Antenna : Antenna long, almost filiform, 28-segmented, about as long as body. Scape 1.5 times longer than its maximum width, ~ 2.0 times longer than pedicel. First flagellar segment rather wide, 4.5 times longer than its maximum width, 1.2 times longer than second segment. Penultimate segment 1.5 times longer than its maximum width, 0.7 times as long as apical segment. Apical antennal segment with distinct distal spine.
Mesosoma : Mesosoma 1.2 times longer than its maximum height. Neck of prothorax short. Mesoscutum anteriorly distinctly convex and weakly protruding forward, without anterolateral corners. Notauli completely absent. Prescutellar depression (scutellar sulcus) rather short, densely crenulate. Scutellum short and weakly convex. Subalar depression shallow and narrow, smooth. Propodeum strongly curvedly narrowed posteriorly (lateral view).
Wings : Fore wing wide, 2.7 times longer than its maximum width. Pterostigma wide, 3.2 times longer than its width. Radial (marginal) cell distinctly shortened, 3.2 times longer than its maximum width. Metacarp (1-R1) 0.7 times as long as pterostigma. Radial vein (r) arising weakly behind middle of pterostigma. First (r) and second (3-RS+SR1) radial abscissae forming obtuse angle; first abscissa (r) 0.4 times as long as maximum width of pterostigma. Second radial abscissa (3-RS+SR1) evenly curved, almost 9.0 times longer than first abscissa (r), 2.7 times longer than first radiomedial vein (2-RS). Recurrent vein (m-cu) distinctly antefurcal, 2.0 times longer than second abscissa of medial vein (2-SR+M), 0.6 times as long as first radiomedial vein (2-RS), 0.45 times as long as basal vein (1-M). First abscissa of medial vein (1-SR+M) weakly sinuate. Discoidal (discal) cell 1.1 times longer than its maximum width. Nervulus (cu-a) 0.8 times as long as distance (1-CU1) between basal vein (1-M) and nervulus (cu-a). Parallel vein (CU1a) distinctly curved basally. Brachial (subdiscal) cell relatively short and rather wide. Hind wing ~ 4.5 times longer than its maximum width. Submedial (subbasal) cell long and wide; first abscissa of mediocubital vein (M+CU) ~ 4.0 times longer than second abscissa (1-M).
Legs : Fore femur wide, ~ 3.3 times longer than its maximum width. Fore tarsus shortened; tarsal segments mainly short. Hind coxa wide and short, massive, ~ 1.3 times longer than its maximum width. Hind femur ~ 4.0 times longer than its width. Hind tibia distinctly thickened. Hind tarsus shorter than hind tibia. Claw simple.
Metasoma : Metasoma curved down posteriorly, approximately as long as head and mesosoma combined. First metasomal tergite with distinct and complete dorsal carinae, approximately as long as propodeum. Second suture perhaps absent. Subposterior sternite with pair of short ventral teeth. Ovipositor wide, compressed and distinctly curved; dorsal valve of ovipositor apically without lobe. Ovipositor sheath rather thin (ventral view), short and wide, narrowed distally, with short apical tubercle (lateral view), covered by rather long and almost erect setae; sheath 2.2 times longer than its width, ~ 0.7 times as long as first tergite.
Sculpture : Body mainly smooth; sculpture of propodeum not visible, but perhaps with transverse carina.
Colour : Body dark brown to black. Palpi yellow. Antenna mainly black, brown basally. Legs mainly light reddish brown or reddish brown, hind tibia dark. Fore wing hyaline. Pterostigma entirely dark brown.
Male. Unknown.
This species is named after Latin “magnus” (large) and “oculus” (eye), because the eyes of the new species are distinctly enlarged.
The new species differs from the type species of the genus Centistoides, C. doesburgi van Achterberg, 1992, primarily by subgeneric characters. The differences between all known species of Centistoides are shown in the key below.
1 | Discoidal (discal) cell of fore wing petiolate anteriorly; first abscissa of medial vein (1-SR+M) arising from basal vein (1-M). Subposterior sternite of metasoma with pair of short ventral teeth. – Prescutellar depression with five transverse carinae. Tarsal claws weakly curved apically. Ovipositor sheath narrowed apically. Fore wing length 3.6 mm. Fossil | C. (Palaeoides) magnioculus sp. nov. |
– | Discoidal (discal) cell of fore wing sessile anteriorly; first abscissa of medial vein (1-SR+M) arising from parastigma. Subposterior sternite of metasoma without ventral teeth | 2 |
2 | First medial abscissa (1-SR+M) of fore wing sinuate; second medial abscissa (2-SR+M) long, 0.6 times as long as recurrent vein. Discoidal (first discal) cell anteriorly narrowly sessile. First transverse anal vein (1a) present. Propodeum with distinct basomedian carina and with areola completely delineated by carinae. Prescutellar depression (scutellar sulcus) sculptured. Ovipositor sheath relatively thick, but flattened on narrow flanges dorsally and apically, rather densely setose apically. Fore wing length 4.7 mm. Afrotropics (Madagascar) | C.(s. str.) ophthalmicus (Granger, 1949) |
– | First medial abscissa (1-SR+M) of fore wing straight; second medial abscissa (2-SR+M) short, ~ 0.3 times as long as recurrent vein. Discoidal (first discal) cell anteriorly broadly sessile. First transverse anal vein (1a) absent. Propodeum without basomedian carina, with areola incompletely delineated by carinae anteriorly. Prescutellar depression (scutellar sulcus) smooth. Ovipositor sheath entirely flatted, truncate and glabrous apically. Fore wing length 3.0 mm. Neotropics (Suriname) | C. (s. str.) doesburgi van Achterberg, 1992 |
The fossil genus and species presumably from the tribe Centistini, Parasyrrhizus ludens Brues, 1933, was described from Baltic amber based on two males in the subfamily Leiophroninae (= Euphorinae) (
Thus, Centistoides (Palaeoides) magnioculus sp. nov. is the first reliable fossil record of Centistini sensu lato found as an inclusion in amber.
It should be noted that in a recent molecular phylogenetic analysis of the subfamily Euphorinae, it was shown that the genus Asiacentistes (which is very similar and probably closely related to Centistoides) does not belong to the Euphorinae s. str. (
The former braconid subfamily Betylobraconinae (currently Betylobraconini in Rogadinae), represented in the Eocene by the genus Mesocentrus Szépligeti, 1900 (
Overall, 45% of Danish amber hymenopteran genera remain unknown from Baltic amber (authors’ data) – one and a half times higher than the proportion of known Rovno amber hymenopteran genera not yet discovered in Baltic amber, and even higher than the proportion of non-ant Rovno amber hymenopteran genera unknown from Baltic amber (41%,
We are very thankful to Prof. Alexandr P. Rasnitsyn (Palaeontological Institute, Moscow, Russia) for his useful consultation and discussion. We are sincerely grateful Madeline V. Pankowski (Rockville, USA) for improving the English of our manuscript. The authors are also very thankful to Prof. Cornelis van Achterberg (Leiden, the Netherlands) and unknown reviewer for their good opinion and useful comments on the first version of the manuscript.
This study was performed as part of the Russian State Research Project No. 122031100272–3 for SAB. EEP was supported by the Scholars at Risk Ukraine (SARU) program, jointly funded by the Villum Foundation, Carlsberg Foundation and Novo Nordisk Foundation, and by the grant “Support and development of the amber collection of the Statens Naturhistoriske Museum” from Dr. Bøje Benzons Støttefond.