First record of the subfamily Oxytorinae (Insecta, Hymenoptera, Ichneumonidae) from the Oriental Region, with descriptions of two new species from Vietnam

Abstract Background The Oxytorinae is a small subfamily of the family Ichneumonidae (Insecta, Hymenoptera) with the single genus Oxytorus Förster and 23 described species. Species were previously known to occur in the Palaearctic, Nearctic and Neotropical Regions. New information The ichneumonid subfamily Oxytorinae is recorded for the first time from the Oriental Region. Two species, one from northern and one from central Vietnam, are described as new: Oxytoruscarinatus Riedel, sp. n. and O.rufopropodealis Riedel, sp. n.


Introduction
The Oxytorinae is a small subfamily of Ichneumonidae (Hymenoptera) that includes only the genus Oxytorus Förster, with 23 described species found in the Palaearctic, Nearctic and Neotropic Regions (Broad et al. 2018). The biology and hosts of Oxytorinae are still unknown. The phylogenetic relationship of Oxytorinae within the Ichneumonidae is still a subject of research and Quicke et al. (2009) proposed an association with the polyphyletic subfamily Ctenopelmatinae. Recent results of a phylogenetic analysis agree with the placement of Oxytorus within Ophioniformes and most likely they are closely related to Ctenopelmatinae (Bennett et al. 2019). Ten species of Oxytorus Förster are known from the Eastern Palaearctic Region (Kasparyan et al. 2014, Sheng andSun 2014), but this subfamily has not been found in the Oriental Region before. Here, we present our finding of two new species of Oxytorus Förster from Vietnam that were recently collected by the second author.

Materials and methods
The present study resulted from capacity building training courses that were part of the ongoing German-Vietnamese VIETBIO project. The project aims at establishing the foundation for future biodiversity joint projects through capacity building and biodiversity research in Vietnam. Field courses took place in two national parks: Bach Ma National Park in central Vietnam (June 2018) and Cuc Phuong National Park in northern Vietnam (April-May 2019). The Bach Ma National Park demarcates the border between north and south Vietnam ranging from lowland to high mountains, with Bach Ma being considered as a biodiversity hotspot (Adler et al. 2016, Kunich 2003, Ngoc et al. 2016, Tobias 2014. The Cuc Phuong National Park in northern Vietnam is located at the junction between the temperate tropical and the subtropical regions. It is amongst the areas with the hightest documented diversity in Vietnam (Larsen et al. 2005, Eguchi et al. 2011. During the field courses, a range of different collecting methods were employed, including Malaise traps, Yellow Pan Traps and net sweeping. Morphological terms and measurements follow Broad et al. (2018), except that the 1 flagellomere was measured without the annellus. For the measurements, an Olympus SZX 7 stereomicroscope with dividing eyepiece was used. The figures were taken with an Olympus SC 30 CCD camera using the AnalySIS getIT software and processed using Helicon Focus (vers. 7.0) and, subsequently, enhanced with Adobe Lightroom Classic.

Diagnosis
The species is characterised within the genus Oxytorus by the transverse carina of the area superomedia and the distinct lateral longitudinal carina of the 2 tergite. Due to the absent vein 3rs-m, the species runs to O. luridator (Gravenhorst, 1820) in the key to Palaearctic species (Kasparyan et al. 2014), but differs by its colour and the unique characters mentioned above.

Type depository
The holotype is deposited in the Vietnam National Museum of Nature, Vietnam Academy of Science and Technology, Hanoi, Vietnam and the paratype in the Zoologische Staatssammlung München, Munich, Germany.

Diagnosis
The species runs to O. kamikochianus (Momoi, 1965) in the key of Kasparyan et al.
(2014), but can been separated by the different colour of the propodeum and the metasoma.

Type depository
The holotype is deposited in the Vietnam National Museum of Nature, Vietnam Academy of Science and Technology, Hanoi, Vietnam and the paratype in the Zoologische Staatssammlung München, Munich, Germany.