Research Article |
Corresponding author: Sergey A. Belokobylskij ( doryctes@gmail.com ) Academic editor: Jose Fernandez-Triana
© 2019 Khuat Dang Long, Sergey A. Belokobylskij.
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:
Long KD, Belokobylskij SA (2019) First record of the genus Rasnitsynoryctes Belokobylskij, 2011 (Hymenoptera, Braconidae, Doryctinae) in Vietnam, with the description of a new species. ZooKeys 854: 17-24. https://doi.org/10.3897/zookeys.854.34810
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The rare doryctine genus Rasnitsynoryctes Belokobylskij, 2011 is recorded for the braconid fauna of Vietnam for the first time. A new species of this genus, R. vietnamicus sp. nov., is described and illustrated.
Ichneumonoidea, new record, Oriental region, parasitoid
The peculiar monotypic Oriental genus Rasnitsynoryctes Belokobylskij, 2011, with type species Rasnitsynoryctes alexandri Belokobylskij, 2011, is a rare taxon from subfamily Doryctinae originally described from Malaysia (Belokobylskij, 2011). The one of the most important features of this genus, presence of longitudinal and weakly convergent posteriorly sublateral furrows, is known in several others Old World genera: several taxa from the tribes Holcobraconini and Leptospathiini, Eodendrus Belokobylskij, 1998; Hypodoryctes Kokujev, 1900; Halycaea Cameron, 1903 and Sonanus Belokobylskij et Konishi, 2001 from Doryctini, Polystenus Foerster, 1863; Spathiostenus Belokobylskij, 1993 and Terate Nixon, 1943 from Hecabolini. Rasnitsynoryctes is additionally characterised by the fore wing with discal (discoidal) cell sessile anteriorly and vein CU1b (brachial) slanted towards base of wing (declivous); hind wing with subbasal (submedial) cell short and with more than three hamuli; inner spur of hind tibia transformed, sinuate and with inner expansion in apical third or submedially.
The hosts of the member from this genus are yet unknown. According to the large size of Rasnitsynoryctes specimens and by analogy to many other large-sized doryctines, species of this genus are probably parasitoids of Cerambycidae larvae or some other large xylophagous beetles inhabiting similar ecological niches.
In this paper we describe and illustrate the new species of the genus Rasnitsynoryctes, R. vietnamicus sp. nov., and additionally, this genus is recorded for the first time for the fauna of Vietnam.
The studied specimen is deposited in the Braconidae Collection of the Institute of Ecology & Biological Resources (IEBR), the Vietnam Academy of Science and Technology, Ha Noi, Vietnam.
Terminology used in this paper follows
We used an Olympus SZ61 binocular microscope for study; measurement were carried out using an Olympus SZ40 binocular microscope; the photographs were made with a Sony 5000 digital camera attached to a Nikon SMZ 800N binocular microscope connected to a PC at IEBR and processed with Adobe Photoshop CS5 to adjust the size and background. Abbreviations used in this paper are as follows:
POL minimum postocellar line;
OOL minimum ocular-ocellar line;
OD maximum diameter of posterior ocellus;
MT Malaise trap;
‘Doryc. + number’ code number indexing for Doryctinae specimens in the collection at IEBR;
NR Nature Reserve.
Rasnitsynoryctes Belokobylskij, 2011: 241.
Rasnitsynoryctes alexandri Belokobylskij, 2011.
Frons weakly concave. Eyes glabrous. Occipital carina dorsally complete, obliterate below at long distance above hypostomal carina. Malar suture absent. Postgenal bridge rather wide. Maxillary palpi long. Notauli complete. Precoxal sulcus narrow and long. Prepectal carina complete. Propodeum with finely delineated basolateral areas; lateral tubercles and propodeal bridge absent. Pterostigma of fore wing rather narrow. Marginal (radial) cell not shortened. Vein m-cu (recurrent) weakly antefurcal. Discal (discoidal) cell sessile anteriorly. Vein CU1a (parallel) arising from posterior 0.2–0.25 of apical margin of subdiscal (brachial) cell. Subdiscal (brachial) cell closed postero-apically by vein CU1b (brachial). Veins 2A and a (first and second transverse anal veins) absent. Hind wing with 5–6 hamuli. Marginal (radial) cell without additional transverse vein r. Subbasal (submedial) cell short; vein M+CU (first abscissa of mediocubital) 0.35–0.40 times as long as vein 1-M (second abscissa). Vein m-cu (recurrent) short, distinctly slanted toward base of wing. Fore tibia with short and thick spines arranged in almost single line. Hind coxa with distinct basoventral tooth. Hind tibia inner spur distinctly sinuate (Fig.
Holotype, female, “Doryc. 673”, NE Vietnam: Bac Giang, Son Dong, Yen Tu NR, 300 m, 4.vii.2010 (PT Nhi leg.) (IEBR).
The new species, Rasnitsynoryctes vietnamicus sp. nov., is very similar to the type species of the genus, R. alexandri Belokobylskij, 2011, from Malaysia; the differences between these species are showed in the key below after description.
Female. Body length 11.7 mm, fore wing length 8.6 mm, ovipositor sheath 12.0 mm (Fig.
Head. Antennae with more than 48 segments (apical segments missing); scapus 1.4 times as long as its maximum width (14 : 10); third segment almost as long as fourth segment (27 : 26); middle segments 3.5–3.7 times as long as their width. Head width (dorsal view) 1.2 times its median length (64 : 52), head roundly narrowed behind eyes (Fig.
Mesosoma. Length 2.3 times its height (77 : 34); mesoscutum highly and perpendicularly elevated above pronotum; median lobe of mesoscutum with distinct median longitudinal depression (Fig.
Wings. Length of fore wing 4.25 times as long as its maximum width (102 : 24) (Fig.
Legs. Inner side of fore tibia with row of short robust spines; middle basitarsus 15.0 times as long as its width (60 : 4) and 0.9 times as long as tarsal segments 2–4 combined (60 : 68); hind coxa 1.6 times as long as its maximum width (52 : 35) (Fig.
Metasoma. Metasoma 1.4 times as long as head and mesosoma combined (69 : 48); first metasomal tergite with large dorsope (Fig.
Sculpture and pubescence. Frons rugose; vertex finely transversely striate; temple finely rugose-punctate; face largely rugose; clypeus and malar space with dense long setae; malar space largely rugose-punctate contrasting to rather smooth area between hypostomal carina and malar space; notauli largely rugose (Fig.
Colour. Black body; antenna brown; head mainly dark brown, subalar space brownish yellow; palpi white; fore and middle legs yellow, except coxa, trochanters and trochantellus cream white; hind coxa and femur black, trochanters and trochantellus yellow, hind tibia (except yellow basal area) and tarsus infuscate; tegula yellow; fore wing subhyaline, its veins brown, outside area of vein r beneath pterostigma brownish; ovipositor sheath brown.
Rasnitsynoryctes vietnamicus sp. nov., female, holotype 2 head, dorsal view 3 head, front view 4 head, lateral view 5 mesonotum 6 mesosoma, lateral view 7 propodeum 8 fore wing 9 hind wing 10 first metasomal tergite 11 hind coxa, outer side 12 second-fifth metasomal tergites 13 hind femur, outer side 14 hind tibia, outer side 15 inner spur of hind tibia 16 hind wing hamuli.
Unknown.
The new species is named after the country (Vietnam) where the holotype was collected.
North-eastern Vietnam (Bac Giang Province).
1 | Vertex without medial longitudinal depression. Propodeum areolate-rugose, with delineated wide areola (Belokobylskij, 2011: fig. 8); first metasomal tergite 1.9 times as long as its apical width (Belokobylskij, 2011: fig. 28); median length of second tergite 0.7 times its basal width; hind wing with five hamuli (Belokobylskij, 2011: fig. 18); hind coxa light brown (Belokobylskij, 2011: fig. 20); hind trochanter pale brown; hind tibia mainly dark (Belokobylskij, 2011: fig. 19). Malaysia | Rasnitsynoryctes alexandri Belokobylskij |
– | Vertex with medial longitudinal depression. Propodeum foveolate-rugose, without delineated areola (Fig. |
Rasnitsynoryctes vietnamicus sp. nov. |
The discovery of a new species from very rare Oriental genus Rasnitsynoryctes supports the opinion that our knowledge of the tropical and subtropical faunas of the parasitoid wasps is very incomplete even for such large-sized specimens (more than 10.0 mm length). Perhaps one of the main reasons for the rarity of such large specimens in a collection is related with peculiarities of their mode of life (preferring the tree canopies), behaviour, and food preferences related with potential hosts habitats. Further investigation of the relict tropical forests and collecting of such parasitoids by different methods and traps (including rearing from the potential hosts in infested plants, especially tree trunks or branches) in numerous habitats may allow to reveal more numbers of such specimens and taxa and to obtain more information about so called “rare” genera and taxa in the tropics.
This research is funded by the Vietnam National Foundation for Science and Technology Development (NAFOSTED), grant No. 106-NN.05-2016.08, for the first co-author and by grant given of the Russian Foundation for Basic Research (project No 19–04–00027) and the Russian State Research Project No. АААА-А19-119020690101-6 for the second co-author. Our thanks are expressed to the editor for the helpful comments on the manuscript; thanks are also due to Dr Pham Thi Nhi (IEBR) for providing the specimen.