The Nemestrinidae in Egypt and Saudi Arabia (Brachycera: Diptera)

Background: The Nemestrinidae are a widespread group of moderate to large‑sized rather stout flies. All known lar‑ vae of these flies are internal parasitoids of nymphs and adults of grasshoppers and larvae of scarabaeid beetles and have the potential to be used as biocontrol agents. Results: All known Egyptian and Saudi Arabian nemestrinid taxa are systematically catalogued in the present study. A total number of 13 species classified in only 2 genera, Nemestrinus (subfamily Nemestrininae) and Trichopsidea (subfamily Falleniinae), were investigated. Twelve of these species are represented in Egypt, out of which 5 species are represented in Saudi Arabia as well. Two of the treated species, Nemestrinus ater (Olivier) and N. rufipes (Olivier), are newly recorded herein from Saudi Arabia. Only one species, Trichopsidea costata (Loew), was recorded exclusively from Saudi Arabia. An updated classification, taxonomic data, world and local distributions with collection dates and coloured photographs of some species were provided. Hope that the results of this study will provide the basis for systematic studies and fauna analyses of future works on Nemestrinidae. It seems likely that further species will be discovered with more research involving a variety of collecting methods. Conclusion: Thirteen nemestrinid species belonging to 2 genera and 2 subfamilies were represented in both Egypt and Saudi Arabia. Two of these species are newly recorded herein from Saudi Arabia.

Page 2 of 9 El-Hawagry et al. Egyptian Journal of Biological Pest Control (2022) 32:26 ( Table 1). No previous studies on Nemestrinidae were carried out in Saudi Arabia; however, Steyskal and El-Bialy (1967) published a list of Egyptian Diptera including Nemestrinidae, and El-Hashash et al. (2021) studied one genus, Nemestrinus, taxonomically in Egypt. Moreover, some species were described from Egypt in some other miscellaneous studies as Olivier (1810), Wiedemann (1828), Macquart (1840) and Efflatoun (1925). Egypt and Saudi Arabia are two neighbouring Arabian countries situated at the junction of the Afrotropical and Palaearctic biogeographic regions. The faunas in both countries are mainly Palaearctic, except for the southeastern corner of Egypt (Gebel Elba) (El-Hawagry et al. 2018) and the south-western district of Saudi Arabia, south to the Tropic of Cancer (El-Hawagry et al. 2017), which are mainly Afrotropical.
The present study is one in a series of studies on different families of Diptera aiming to catalogue the entire order in both Egypt and Saudi Arabia.

Methods
Previous studies concerning the Nemestrinid flies in Egypt and Saudi Arabia, in addition to material deposited in Egyptian and Saudi Arabian museum or collected by the authors, were the main sources for the present study. Different collecting methods were used, included sweeping nets, Malaise traps, pitfall traps and light traps; however, majority of specimens were collected by the sweeping nets and only two specimens of Trichopsidea costata were collected by pitfall trap and light trap, as one specimen by each.
The classification of Papavero and Bernardi (2009) is considered in the present study, in which the extant genera of Nemestrinidae are classified in 5 subfamilies: Atriadopinae, Cyclopsideinae, Falleniinae, Hirmoneurinae and Nemestrininae. The classification of species within genera follows Richter (1988).
Taxonomic information as type species, type localities and synonymies was mainly obtained from Richter (1988). However, world and local distributions, and collection dates of species were obtained from different relevant literature, in addition to local museums and/or collected specimens. These sources are listed in square brackets at the end of each section.
In the sections of localities and dates of collection, the 8 known Egyptian ecological zones (Coastal Strip (CS), Eastern Desert (ED), Fayoum, Gebel Elba (GE), Lower Nile Valley & Delta (LNVD), Sinai, Upper Nile Valley (UNV) and Western Desert (WD)) were adopted in the present study. However, there are no evident ecological zones in Saudi Arabia, so the administrative divisions (also known as regions or provinces) were used instead, namely, Al-Baha, Al-Jawf, Al-Madinah, Al-Qaseem, Asir, Eastern Province, Hail, Jazan, Makkah, Najran, Northern Frontier, Riyadh and Tabuk.
Localities within each Egyptian ecological zone or Saudi Arabian administrative region are alphabetically arranged and written after a colon following each zone or region and then followed, between parentheses, by the collection dates. Coordinates of nemestrinid localities in Egypt and Saudi Arabia are listed (Table 2).      Note. Egyptian records of this species were taken from an old list of species preserved in ESEC. However, these records seem to be doubtful and we could no t check them. The collection in ESEC was closed at the present time for unknown reasons and material was thought to be abandoned there.
[Source: Macquart (1840), Richter (1988) Lichtwardt (1909), Abdu and Shaumar (1985), Richter (1988) Note. This species was recorded herein for the first time from Saudi Arabia and the Afrotropical Region, considering the south-western district of Saudi Arabia as affiliated to the Afrotropical Region.

Discussion
Only 5 species of Nemestrinidae were treated in the present study as recorded from Saudi Arabia. The number of species is still low and does not represent the real fauna of the family in this large country. However, this low diversity of species should be interpreted cautiously, since the family, as many other dipterous families, seems to lack sampling efforts in Saudi Arabia and extensive faunistic and systematic studies are required. On the other hand, comprehensive surveys by late Efflatoun Bey and his coworkers and their followers started in Egypt more than 100 years ago (El-Hawagry et al. 2020). These surveys resulted in considerable number of nemestrinid flies pinned and preserved in the Egyptian insect collections.
El-Hashash et al. (2021) synonymized Nemestrinus abdominalis Olivier (1810) and Nemestrinus fascifrons (Bigot 1888) with Nemestrinus ater (Olivier, 1810). However, they did not check the types of these 3 species, and they almost based on original descriptions and/or some specimens preserved in EFC. They assumed that these specimens were identified by late Efflatoun Bey as N. fascifrons and N. ater. They stated that all specimens were of one sexually dimorphic species as males were identified as N. fascifrons and females as N. ater. Consequently, they synonymized N. fascifrons with N. ater based on this assumed Efflatoun's identifications. However, these specimens are not types and there were no labels in the box or under any specimen to indicate who identified them. So, these identifications are doubtful and may be wrong. In like manner, there are no specimens of N. abdominalis preserved in any Egyptian insect museum to be checked. Consequently, we cannot adopt these synonymies without checking the types which are not available for us. Our viewpoint agrees with that of Sack (1933) and Paramonov (1945) who keyed the 3 species and clearly differentiated between them using identifiable features. Lichtwardt (1909) and Bequaert (1938) synonymized Nemestrinus ruficornis (Macquart, 1840) with Nemestrinus rufipes (Olivier, 1810). However, Sack (1933), Paramonov (1945) and Richter (1988) considered it as a separate valid species. El-Hashash et al. (2021) adopted the first opinion and considered the 2 species as synonyms without checking the type material or any other material of N. ruficornis and based only on the original descriptions. Types of this species were not available to validate its classification. Consequently, we cannot adopt this synonymy as well.
Hope the results of this study may provide the basis for systematic studies and fauna analyses of future works on Nemestrinidae. It seems likely that further species will be discovered with more research involving a variety of collecting methods.

Conclusions
In the present study, the family Nemestrinidae was catalogued in both Egypt and Saudi Arabia. The study revealed that 13 nemestrinid species belonging to 2 genera, Nemestrinus and Trichopsidea, and 2 subfamilies, Nemestrininae and Falleniinae, were represented in the two countries. Two of these species, Nemestrinus ater (Olivier) and N. rufipes (Olivier), are newly recorded from Saudi Arabia.