A Taxonomic Study on the Genus Naddia from China (Coleoptera, Staphylinidae, Staphylininae) with Descriptions of Two New Species

Simple Summary Naddia is a genus of rove beetles distributed in Asia particularly in its south-eastern part. The species of the genus usually have a large body size and can be recognized by the emarginated base of the head. Naddia species are found to be mimics of sphecid or vespid wasps in both behavior and appearance, which is reported in this paper for the first time. With two new species described in the present paper, 39 species are known from the world, and 12 species are known from China. Abstract Two new species of Naddia from China are described: N. chenchangchini sp. nov. (Guangxi) and N. hujiayaoi sp. nov. (Zhejiang, Fujian, Jiangxi, Hunan, Guangxi, Guangdong). Naddia atripes Bernhauer, 1939 is new to Vietnam and the following Chinese provinces: Jiangxi, Guangxi, Jiangsu, Shaanxi, Hunan, Hubei, Sichuan, Guizhou, Fujian and Guangdong. Naddia chinensis Bernhauer, 1929 is new to Zhejiang, Jiangsu, Guizhou, Henan, Hunan, Shaanxi, Fujian, Chongqing, Guangxi and Hubei. Naddia miniata Fauvel, 1895 is new to Laos. A key to Chinese species of the genus is provided.


Introduction
Naddia Fauvel, 1867 is a strictly Asian genus of the rove beetle subtribe Staphylinina. The genus can be readily distinguished from other members of Staphylinina by the deeply (rarely moderately) emarginated base of the head and a characteristic aedeagus with a flat and spoon-shaped apical portion of the median lobe in most species [1,2], some species having a weakly sclerotized subapical portion. The paramere is variable in size, from gladiate to very inconspicuous in shape, with a tiny rudiment at the aedeagal base. A few setae are always situated at the tip of the paramere, and sometimes they are arranged in two groups. The length of the setae can be used as character to distinguish similar species, e.g., in N. chinensis and N. miniata. A complex of sclerites exists in the aedeagal inner sac, although it is indistinct in some species.

Materials and Methods
The specimens examined in this paper were collected individually from the ground, by sifting leaf litter and by flight intercept traps and pitfall traps. They were subsequently killed with ethyl acetate. For examination of the genitalia, the last three abdominal segments were detached from the body after softening in hot water. The aedeagus together with other dissected pieces were mounted in Euparal (Chroma Gesellschaft Schmidt, Koengen, Germany) on plastic slides beneath the carded specimens. Photos of sexual characteristics were taken with a Canon G9 camera attached to an Olympus SZX 16 stereoscope; habitus photos were taken with a Canon macro photo lens MP-E 65 mm attached to a Canon EOS 7D camera and stacked with Zerene Stacker (http://www.zerenesystems.com/cms/stacker, accessed on 12 May 2022).
The specimens treated in this study are deposited in the following collections: CFEN-Private collection of Zhen-Hao Feng, Nanjing, China CSHUB-Collection of Michael Schülke, in "Museum der Alexander Humboldt Universität", Berlin, Germany NMW-Natural History Museum Wien, Austria SHNU-Department of Biology, Shanghai Normal University, Shanghai, China Body measurements are abbreviated as follows: BL-body length, measured from the anterior margin of the clypeus to the posterior margin of abdominal tergite X FL-forebody length, measured from the anterior margin of the clypeus to the apex of the elytra (apicolateral angle) HL-length of head along the midline HW-width of head including eyes CL-length of eye PO-length of post-ocular region PL-length of pronotum along the midline PW-width of pronotum at the widest point EL-length of elytra, measured from humeral angle EW-width of elytra at the widest point  Figure 1A,B), it is extremely similar to N. chinensis, which was later described from China. The differences between N. miniata and N. chinensis were previously mentioned in the shape of head or body [7,8]. Dr. Aleš Smetana, who examined the types of both species, could not detect reliable differences between them and supposed that N. chinensis should be synonymized with N. miniata (personal communication). By examining large series of specimens with similar appearance from China in various collections, the specimens from Yunnan and Laos are found to be different from other specimens by the much longer setae on the paramere (Figure 2A-D). Considering the geographical distribution, the specimens from Yunnan are regarded as N. miniata in this paper. In addition, the elytral pubescence of N. miniata is more reddish. The distributional records of Jiangxi and Sichuan for N. miniata in the previous paper [8] are assigned to the distribution of N. chinensis.    Diagnosis. The species is extremely similar to N. miniata, both in appearance ( Figure 1C,D) and in shape of the aedeagus. It may be distinguished from the latter by the shorter setae on the aedeagal paramere ( Figure 2E-H) and the generally denser reddish pubescence on the elytra. The ratios of HW/HL are quite variable in N. chinensis; therefore, this characteristic is not very helpful in recognizing N. miniata and N. chinensis. Naddia taiwanensisShibata, 1979 Naddia taiwanensis Shibata, 1979, 19;Hu, 2020 Diagnosis. The species was described from Taiwan without comparing it to N. chinensis, most likely because the author did not know the latter. In fact, N. taiwanensis is almost identical to N. chinensis except for the antennal segments 8-11, which are relatively shorter than those of N. chinensis. Examining more specimens of N. taiwanensis will be necessary to evaluate if it is a valid species.

Naddia
Naddia Body blackish, elytra coppery with reddish pubescence, lateral portions of abdominal tergites III-VI with patches of golden pubescence (less distinct on tergite VI in one specimen), tergite VII with a patch of golden pubescence in basal half, mouthparts and tarsi brownish, antennae dark brown.
Distribution. China (Fujian, Guangdong, Hunan). Diagnosis. The brachypterous species is similar to three full-winged species, N. miniata, N. chinensis and N. taiwanensis in general appearance ( Figure 3A,B), but it can be easily distinguished from those by shorter elytra and posterior margin of abdominal tergite VII without distinct palisade fringe.  Pronotum widest at anterior angles, anterior angles distinctly prominent, lateral margins distinctly curved ventrad slightly in front of midlength; dorsal surface with punctures similar to those of head; an impunctate midline exists in posterior third.
Elytra with lateral margins slightly divergent posteriad, punctation very dense and fine. Scutellum densely and finely punctate, pubescence black.
Abdominal tergites with dense punctation and short pubescence.
Male. Sternite VIII with posterior margin emarginate in the middle; aedeagus ( Figure 4E-H) symmetrical, median lobe elongated, middle portion weakly sclerotized, nearly transparent, inner sac with sclerotized sclerites; paramere very short, separated into two pieces with few apical setae.   Female. Sternite VIII with posterior margin entire.

Distribution. China (Guangxi).
Diagnosis. The new brachypterous species is extremely similar to N. mangshanensis, but it can be distinguished from the latter by in average larger size, abdominal tergite VI with longitudinal golden pubescent patches laterally, lobes of paramere more distinctly pointed and with longer apical setae ( Figure 4E-H).
Etymology. This species is named in honor of Mr. Chang-Chin Chen, who donated Naddia specimens of the new species to us.   Hunan). Diagnosis. The brachypterous species is somewhat similar to N. mangshanensis with overlapping distribution, but it can be easily distinguished from the latter by the following characteristics: elytra black without bronze tint, apical margin of terminal antennal segment markedly concave, forming an acute tip, ventral side of head without impunctate areas at posterior angles.  Distribution. China (Taiwan). Diagnosis. The species is similar to the new species N. hujiayaoi, and it may be distinguished from the latter by differently shaped patch of silvery pubescence on the elytral disc ( Figure 5E) and shorter aedeagal paramere compared with median lobe (Figure 7E-H). Description. Measurements of male:   Body blackish, elytra blackish with golden, silver and black pubescence, lateral portions of abdominal tergites III-V with silver pubescence, tergite VII with a band of silver pubescence in basal half, mouthparts and tarsi brownish, antennae blackish, apical third of terminal segment brownish.
Pronotum widest at anterior angles, anterior angles distinctly prominent; dorsal surface with punctures similar to those of head; an impunctate midline present in posterior fourth.
Male. Sternite VII slightly emarginate in middle of posterior margin; sternite VIII rounded emarginate in middle of posterior margin; 9th sternite triangularly emarginate in middle of posterior margin; aedeagus (Figure 9A-D) symmetrical, median lobe elongated, inner sac with weakly sclerotized sclerites; paramere slender, distinctly shorter than median lobe, slightly curved ventrad in lateral view, with few apical setae.
Female. Sternite VIII with posterior margin entire. Distribution. China (Zhejiang, Fujian, Jiangxi, Hunan, Guangxi, Guangdong). Diagnosis. The new species is similar to N. monticola  in general appearance, but it may be distinguished from the latter by continued elytral pubescence patch at middle of posterior margin (interrupted in N. monticola) and longer aedeagal paramere compared with median lobe (Figure 9A-D). Abdominal tergites III-VI each with punctation of median portion gradually becoming sparser apicad.
Male. Sternite VII slightly emarginate in middle of posterior margin; sternite VIII rounded emarginate in middle of posterior margin; 9th sternite triangularly emarginate in middle of posterior margin; aedeagus (Figure 9A-D) symmetrical, median lobe elongated, inner sac with weakly sclerotized sclerites; paramere slender, distinctly shorter than median lobe, slightly curved ventrad in lateral view, with few apical setae.  it is flying. The same applies to their morphological appearance. The first three abdominal segments of Naddia are often blackish with patches of golden pubescence laterally ( Figure 10A-D). These patches of golden pubescence gradually become smaller apicad, and as a contrast, the median blackish parts gradually become larger apicad. Such combination may provide an illusion to predators that Naddia species have a slender waist as that of wasps. This imitation is especially effective in the forests, where the light is less strong.

Conclusions
The species of Naddia have excellent visual sense. Detecting the approach of the collector, they usually tend to catalepsy for a while ( Figure 10D). The time span of catalepsy can be pretty long at lower temperature and vice versa. If the catalepsy strategy fails, they run fast to find a shelter. In this case, species with smaller size sometimes may also try to fly away, but this has never happened in N. chinensis.

Conclusions
The species of Naddia have excellent visual sense. Detecting the approach of the collector, they usually tend to catalepsy for a while ( Figure 10D). The time span of catalepsy can be pretty long at lower temperature and vice versa. If the catalepsy strategy fails, they run fast to find a shelter. In this case, species with smaller size sometimes may also try to fly away, but this has never happened in N. chinensis.