Discovery of the genus Nipponodipogon Ishikawa in the Oriental region, with description of two new species from China (Hymenoptera, Pompilidae)

Abstract The genus Nipponodipogon Ishikawa, 1965 is newly recorded from China (Guangdong, Hainan, and Yunnan) and the Oriental Region. Two new species, N. orientalis Loktionov, Lelej & Xu, sp. n. (Guangdong, Hainan, Yunnan) and N. shimizui Loktionov, Lelej & Xu, sp. n. (Guangdong, Yunnan), are described and illustrated. The updated key to the species based on Shimizu et al. (2015) is given.


Introduction
The family Pompilidae (spider wasps) is one of the largest families among the aculeate wasps in Hymenoptera. The family numbers around 5000 recent species in 125 genera and five subfamilies in the World (Aguiar et al. 2013, Waichert et al. 2015, 650 species in the Palaearctic (Lelej and Loktionov 2012a). The spider wasps are distributed worldwide, but mostly in the tropical regions (Pitts et al. 2006). The spider wasps are parasitoids that use spiders as host provisioning each cell with a single paralyzed spider on which they lay an egg (Iwata 1976). Some genera have evolved the mode of cleptoparasitism (Wasbauer 1995, Shimizu 2000, O'Neill 2001, Shimizu et al. 2012. One of such cleptoparasitic genera is Nipponodipogon Ishikawa, 1965, a representative of brood parasitic wasps. Shimizu and Ishikawa (2002) pointed out the peculiar features in their antennal structure: the antenna is short, stout, and thickened toward middle of flagellum, and F2-F10 are somewhat flattened on the anteroventral side. Shimizu et al. (2012) confirmed the brood parasitism of N. nagasei and N. iwatai by using trap-nest technique. Based on several pieces of circumstantial evidence obtained from the contents of trap nests, they concluded that both species brood-parasitize species of Deuteragenia Šustera, 1912 (tribe Deuterageniini), and N. iwatai broodparasitizes species of Auplopus Spinola, 1841 (tribe Auplopodini). They also discovered, that female of N. nagasei routinely lays up to five eggs on a single host spider, all of which develop into adult wasps without larval cannibalism; instead all spider wasps previously studied lay only one egg on a host spider (Shimizu et al. 2012).
Nipponodipogon, from the tribe Deuterageniini, subfamily Pepsinae, is distributed so far in the Eastern Palaearctic: in the Japanese Archipelago and the south of the Russian Far East. Ishikawa (1965) created this taxon as a subgenus of the genus Dipogon Fox, 1897, based on three species from Japan, Dipogon (Nipponodipogon) iwatai Ishikawa, 1965 (Honshu), D. (N.) nagasei Ishikawa, 1965 (Honshu and Kyushu) and D. (N.) mandibularis Ishikawa, 1965 (Honshu), the first of which is the type species. Later, Ishikawa (1968) described one species, D. (N.) hayachinensis Ishikawa from Japan, and Lelej (1986) described two species: D. (N.) rossicus Lelej and D. (N.) kurilensis Lelej from the Russian Far East. In the phylogenetic analysis of the tribe Deuterageniini (Lelej and Loktionov 2012b), Nipponodipogon, as well as, other subgenera of the genus Dipogon were proposed as separated genera. Shimizu et al. (2015) revised the genus Nipponodipogon, and described N. sudai Shimizu from Japan. Before this study, the genus included seven species that have been known from Japan and the Russian Far East Lelej 2014, Shimizu et al. 2015).
In this paper we describe two new species of Nipponodipogon from China and enlarge the distribution of the genus to include China and the Oriental Region.

Materials and methods
During the study of hymenopteran collection in South China Agricultural University, we examined more than 2300 specimens of Chinese spider wasps collected during last two decades from Jilin, Inner Mongolia, Ningxia, Gansu, Shaanxi, Henan, Zhejiang, Hebei, Fujian, Hunan, Guangdong, Hainan, Guangxi, Yunnan, Sichuan, and Guizhou. Of them only 14 specimens belonging to the genus Nipponodipogon were collected in 2006, 2010, and 2011  To study male genitalic characters, genitalia were extracted after being previously softened. The muscles were removed in a sodium hydroxide solution (NaOH 10%). The genitalia were later placed in water to neutralize the NaOH and stored in micro vials filled with glycerin. Male genitalia were studied under a stereomicroscope in a depression slide.
Photographs of imagos and genitalia were taken with stereomicroscope SteREO Discovery.V12 and stacked using CombineZM software (Hadley 2008). The final illustrations were post-processed for contrast and brightness using Adobe® Photoshop® software.
The terminology for morphology is mostly based on the glossary provided by the Hymenoptera Anatomy Consortium (2013) and Shimizu et al. (2015). The terminology of wing venation and cells follows Day (1988). The following abbreviations are used for morphological terms:
Body with gray pubescence mostly short, but longer on clypeus, mesopleuron, propodeum posterolaterally and coxae. Body without setae except the following: upper frons sometimes with one long erect setae and a few shorter ones; clypeus with a few long suberect setae anteriorly; coxae and T1 basally with scattered short erect setae; S2-S5 with scattered longer erect setae posteriorly; T6 and S6 with denser long erect pale setae.
Pronotum with anterior declivity weakly concave, more differentiated from dorsum than in female; dorsum in dorsal view narrowing anteriorly; shoulder gently rounded; juncture between dorsal and lateral faces roundly raised; posterior margin weakly and arcuately emarginate. Mesoscutum slightly sloped anteriorly; parapsidal sulcus finely impressed. Discs of mesoscutellum and metanotum somewhat more strongly raised above level of mesoscutum and propodeum than in female. Metapostnotum (Fig. 15) longer and not deeply sunken between metanotum and propodeum, as in female; somewhat narrowing in middle; metapostnotum length 0.15-0.25× metanotum length medially. Propodeum evenly convex with posterior declivity not differentiated from dorsum; posterior surface evenly convex.
Sex association. In spite of the fact that females and males were collected in different locations (two males from Yunnan and five females from Guangdong and Hainan) and have different coloration (mesosoma completely yellow orange in female vs completely black in male), we consider that they are opposite sexes of same species. Male of new species has propodeum with fine transverse striae posterolaterally that correlates with strong transverse rugae on propodeum posteriorly, especially in posterolateral portion in female (vs male without any striae, female with fine transverse striae in Nipponodipogon shimizui sp. n.). Such coloration differences in female and male of new species are not exception and occur in widely distributed Palaearctic species Arachnotheutes rufithorax (Costa, 1881) (Fig. 30). T1 with distinct petiole basally (Fig. 28). Crossvein 2rs-m almost straight or sometimes barely curved; crossvein 3rs-m straight or almost straight (Fig. 31). Mesoscutum raised along midline (Fig. 29). Head and mesosoma matt; metasoma somewhat polished. Male. T1 distinctly petiolate basally (Fig. 38). F3-F11 not produced triangularly beneath, not forming serrated profile. Propodeum polished, without any striae (Fig. 38). Subbasal portion of hypopygium with angulate sublateral carina (Fig. 42, arrow).
Head and mesosoma matt. Frons, vertex and mesosoma, except propodeum, finely and densely punctate. Pronotum laterally and finely striate and punctate. Mesopleuron with denser and coarser punctures then on disc of pronotum. Upper mesopleuron rugose. Metapleuron finely and densely striate. Lateral side of metanotum with several regular oblique striae. Propodeum strongly and densely punctate with fine transverse rugae posteriorly. Metasoma somewhat polished, except T6 and S6 matt. T1-T5 with fine punctures; T6 finely shagreened, without distinct setiferous pores; S6 less shagreened, than T6, with scattered setiferous pores located posteriorly and posterolaterally; S1-S5 with somewhat larger punctures than on T1-T5. S1 with several longitudinal rugae medially. Transverse groove on S2 gently arcuate. Body with gray pubescence mostly short, but longer on propodeum posterolaterally. Body without setae except the following: upper frons sometimes with one long erect setae; clypeus with a few long suberect setae anteriorly; S2-S5 with scattered long or short erect setae posteriorly; T6 and S6 with denser long erect pale setae.
Pronotum with anterior declivity weakly concave, more differentiated from dorsum than in female; dorsum in dorsal view narrowing anteriorly; shoulder gently rounded; juncture between dorsal and lateral faces roundly raised; posterior margin arcuately emarginate. Parapsidal sulcus finely impressed. Discs of mesoscutellum and metanotum somewhat stronger raised above level of mesoscutum and propodeum than in female. Metapostnotum longer and not deeply sunken between metanotum and propodeum, as in female; somewhat narrowing in middle; metapostnotum length 0.25× metanotum length medially. Propodeum evenly convex with posterior declivity not differentiated from dorsum; posterior surface evenly convex.
Sex association. In spite of females and males were collected in different locations (one male in Yunnan and six females in Guangdong), we consider that they are opposite sexes of the same species. Male S6 of new species lacks setiferous pores posteromedially (Fig. 39), which correlates with female S6 of similar condition medially (vs with scattered setiferous pores in male and female of Nipponodipogon orientalis sp. n.).
Etymology. It is a pleasure to name this species after the well-known taxonomist Dr. Akira Shimizu (Tokyo Metropolitan University, Japan).