First record of the genus Rasnitsynoryctes Belokobylskij, 2011 (Hymenoptera, Braconidae, Doryctinae) in Vietnam, with the description of a new species

Abstract 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.vietnamicussp. nov., is described and illustrated.

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.

Materials and methods
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 van Achterberg (1993), while sculpture terms are based on Harris (1979). The wing venation nomenclature follows van Achterberg (1993), with Belokobylskij and Maetô (2009) terminology shown in parentheses.
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: 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. 15) and with inner expansion in apical third. Basitarsus of hind tarsus 0.9-1.1 times as long as second-fifth segments combined. First metasomal tergite not petiolate, long and wide; acrosternite of first segment short, about 0.15 times as long as first tergite. Dorsope of first tergite large; spiracular tubercles situated in basal 0.25 of tergite. Second tergite with deep, weakly convergent posteriorly and fused with second suture sublateral furrows. Suture between second and third tergites rather deep, narrow, widely curved medially and laterally with distinct breaks. Second to sixth tergites with separate laterotergites. All tergites and laterotergites covered by very dense, short, white setae. Ovipositor apically with two obtuse, small dorsal nodes. Comparative diagnosis. 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.
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.
Male. Unknown. Etymology. The new species is named after the country (Vietnam) where the holotype was collected.

Conclusions
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.