﻿Review of Chinese species of the genus Thoracostrongylus Bernhauer, 1915 (Coleoptera, Staphylinidae, Staphylininae)

﻿Abstract Species of the genus Thoracostrongylus Bernhauer, 1915 occurring in China are reviewed. Four new species and one new subspecies are described: T.baishanzuensissp. nov. (Zhejiang), T.bicolorsp. nov. (Guangdong, Guangxi, Hunan, Yunnan), T.brachypterussp. nov. (Sichuan), T.chrysitessp. nov. (Fujian), and T.formosanusflavipesssp. nov. (Zhejiang, Fujian, Hubei, Hunan, Sichuan, Guangxi, Guangdong, Anhui, Jiangxi). A new synonymy is proposed: T.baoxingensis Yang, Zhou & Schillhammer, 2011 syn. nov. is in fact T.acerosus Yang, Zhou & Schillhammer, 2011. New provincial records for T.acerosus Yang, Zhou & Schillhammer, 2011 are reported. A key to Chinese species of the genus is provided.


Introduction
is a genus strictly distributed in east and southeast Asia. It was originally established as a subgenus of Ontholestes Ganglbauer, 1895, and later regarded as a separate genus (Blackwelder 1952). Thoracostrongylus can be readily distinguished from Ontholestes by the obtuse anterior angles of the pronotum (Smetana and Davies 2000), from Lesonthotes by the sparse, simple punctation of the forebody, and the sharply defined temples of the head (Brunke and Smetana 2019). Most IZCAS Institute of Zoology, Chinese Academy of Sciences, Beijing, P. R. China; MSC Michael Schülke Collection, in Museum für Naturkunde, Berlin, Germany; NMW Naturhistorisches Museum Wien, Austria; SHNU Department of Biology, Shanghai Normal University, P. R. China; VAC Volker Assing Collection, Hannover, Germany † (will be deposited in Zoologisches Museum, Berlin).
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; CL length of eye; EL length of elytra, measured from humeral angle; EW width of elytra at the widest point; 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; PL length of pronotum along the midline; PO length of post-ocular region; PW width of pronotum at the widest point. Distribution. China (Hubei, Sichuan, Shaanxi, Gansu, Henan). New to Shaanxi, Gansu, and Henan.
Remarks. The apical portion of the median lobe and the paramere are subject to some variability . This may be observed not only in populations from different localities but also within one population. A closer inspection of the types of T. baoxingensis and T. acerosus revealed that this is the case here as well and that both species are conspecific.    Yang, Zhou &Schillhammer, 2011, andT. diaoluoensis Yang, Zhou &Schillhammer, 2011 in general appearance, but it can be distinguished from them by the apex of median lobe pointed dorsad forming an apical tooth in lateral view, and from T. diaoluoensis also by the aedeagal median lobe with a subapical tooth on the dorsal side. Aedeagal variation (Figs 17-32) occurs in the apical parts of median lobe and paramere.
Distribution. China (Yunnan). ( Diagnosis. The apical portion of the median lobe (Figs 42-45) of the specimen examined here is a little wider than that of the type illustrated in the original description, which is considered as intraspecific variation. The species can be recognized from similar species by median lobe of the aedeagus without an apical or subapical tooth on the dorsal side.

Thoracostrongylus birmanus
Distribution. China (Hainan). Diagnosis. The subspecies is most similar to T. velutinus from Yunnan and Myanmar, but can be easily distinguished by the usually black mid and hind tibiae and tarsi. Both differ from other species from east and southeast China in the abdominal tergites III-VI without triangular mediobasal golden tomentose patch.

Thoracostrongylus formosanus formosanus Shibata, 1982
Distribution. China (Taiwan). Diagnosis. The new subspecies differs from the nominate subspecies in the slightly shorter tempora, and entirely reddish to yellowish antennae and legs (except a dark band on the femora), while the nominate subspecies has almost entirely dark antennae, and black tibiae and tarsi. Even in paler (teneral) specimens of the nominate subspecies, the antennae and legs are at least partly darkened.
Distribution. The subspecies is widespread in China (Zhejiang, Fujian, Hubei, Hunan, Sichuan, Guangxi, Guangdong, Anhui, Jiangxi). Diagnosis. The species shows some intraspecific variability  in the shape of the paramere and median lobe of the aedeagus. In general appearance, the species is similar to T. acerosus, T. aduncatus, and T. diaoluoensis, but can be keyed out by the aedeagal characters.
Distribution. China (Fujian). Distribution. China (Yunnan), Myanmar. Remarks. The species was originally described from Myanmar, and was recorded from China by Yang, Zhou & Schillhammer in 2011 based on the one female mentioned above. However, there were some inconsistencies concerning morphometrics in that paper: The character used in the key "ratio of eye longitudinal diameter to temple length < 3", applies only to the male. However, the measurements of female T. malaisei in the same paper were written as "CL: 0.98; PO: 0.28", and the ratio of CL/PO should be 3.5 by calculation, which conflicts with the key. Thoracostrongylus malaisei is most closely related to T. brachypterus sp. nov.; for diagnosis of these two species, see under the latter. Bernhauer, 1943Figs 73, 116 三宅钝胸隐翅虫 Thoracostrongylus miyakei Bernhauer, 1943Yang et al. 2011: 428;Hu 2020 Yang et al. (2011) is doubtful: the record was published based on a specimen from Sichuan in coll. NMW. However, such a specimen does not exist, but there is a male (identified as T. miyakei) from Yunnan that was not mentioned in Yang et al. (2011). Numerous specimens from the mainland of east China have been examined in this paper and none of them is T. miyakei, creating a huge distributional gap between Sichuan and Taiwan. In addition, T. miyakei is a brachypterous species, making its occurrence in mainland China very unlikely. Since no male of that species from Taiwan was available for this paper, the solution to this problem must wait until males from Taiwan can be studied. Bernhauer, 1915h: 233. Thoracostrongylus sarawakensis: Hammond 1984. Ontholestes (Thoracostrongylus) doriae Gridelli, 1924: 207. Synonymized by de Rougemont 2016: 568. Amichrotus doriae : Hammond 1984: 194, 195.  Diagnosis. The species can be easily distinguished from other species from southwest China by the abdominal tergites III-VI without a triangular, mediobasal, golden tomentose patch. In general appearance, T. velutinus is most similar to T. formosanus, but may be distinguished from the nominate ssp. of the latter by its smaller body size and paler mid and hind legs, and from T. formosanus flavipes by the dark antennae.

Amichrotus sarawakensis
Distribution. China (Yunnan), Myanmar. Diagnosis. The new species can be easily recognized by the combination of following characters: legs reddish yellow without dark markings, head slightly wider than or as wide as elytra, apical portion of median lobe of aedeagus (Figs 82-85 Description. Forebody dark brown with a bronze tint, abdominal segments III and IV reddish brown, remaining segments gradually becoming darker apicad, labrum reddish brown, mandibles reddish brown with medial portions distinctly darker, maxillary and labial palpi reddish brown, antennae reddish brown, antennal club indistinctly darker, legs reddish brown without dark markings, elytra with few small patches of whitish pubescence, scutellum with black pubescence in apical half, abdominal tergites III-VII each with triangular mediobasal golden tomentose patch delimited by pair of dark tomentose spots, dark tomentose spots of tergites III and IV indistinct, dark tomentose spots of tergite V particularly large and dark, confluent apically, forming sagittate patch, dark tomentose spots of tergite VI similar to that of tergite V, but little smaller and distinctly lighter, dark tomentose spots of tergite VII indistinct.
Head slightly wider than or as wide as elytra; vertex with small longitudinal specular spot medially; surface densely covered with umbilicate punctures except specular median spot. Antennae with antennomere 1 longest, antennomeres 2 and 3 almost half as long as antennomere 1, antennomeres 4 and 5 longer than wide, antennomeres 6-10 gradually increasing in width and decreasing in length, antennomere 10 slightly longer than or as long as wide, antennomere 11 distinctly longer than wide, asymmetrical and subacuminate towards tip.
Pronotum widest behind anterior angles; punctation dense and umbilicate, very short and narrow impunctate midline in posterior quarter, pubescence golden, distinct on entire dorsal surface.
Elytra subquadrate, inconspicuously wider than long, slightly dilated posteriad; surface densely and finely, regularly punctate, with brassy pubescence, mixed with grey spots all over the disc. Scutellum triangular, finely and densely punctate, with black, velvety pubescence.
Etymology. This species is named after the type locality, Baishanzu, in Zhejiang Province, China. Diagnosis. The new species is similar to T. baishanzuensis sp. nov., but it can be easily recognized from latter by the bicolored femora. From other species of east and southeast China, it can be easily recognized by the bicolored abdomen. Description. The new species is similar to T. baishanzuensis sp. nov. in most aspects except for the following characters: abdominal tergites III-VII each with a longer and more distinct triangular, mediobasal, golden tomentose patch; femora each with median dark mark and apical dark mark, although the apical dark markings of the forelegs are less distinct.

Thoracostrongylus bicolor
Male. Sternite VIII with medioapical emargination. Aedeagus (Figs 88-95) slender, median lobe gradually narrowed apicad with round apex in ventral view, apex of median lobe expanded dorsad in lateral view; paramere relatively long, apex wide and round with approximately 11 setae around the apical margin.
Etymology. This species is named after its bicolored abdomen.  Diagnosis. The new species is the only brachypterous species of the genus so far that is known from mainland China, except for a potential record of a brachypterous T. malaisei, from which it can be separated as indicated above. The T. malaisei specimens from the type locality have rather short elytra and developed hindwings, which may be functional or not since the palisade fringe on tergite VII is very narrow. Thoracostrongylus miyakei from Taiwan also has weakly developed, non-functional hind wings and no palisade fringe on tergite VII, which differs from the new species by pronotum without impunctate midline. Description. The new species is almost identical to T. malaisei, from which it differs, in addition to the different aedeagus, by the differently colored labrum, which is reddish with each lobe with a large, dark brown, central spot (in T. malaisei with a black medial margin along medial excision). Most specimens of T. malaisei have at least a very narrow palisade fringe on tergite VII, which is lacking only in the single specimen from Yunnan.
Male. Sternite VIII with medioapical emargination. Aedeagus (Figs 98-101) slender and long, median lobe swollen in middle third and then narrowed apicad in ventral view; in lateral view, median lobe with subapical tooth on dorsal side in apical sixth; paramere rather wide, subparallel-sided, apical margin with slight medial notch, with approximately seven setae.
Etymology. This specific name (derived from Greek) means "short winged". Diagnosis. The new species can be easily recognized by the reddish yellow femora and abdominal tergite VII fully covered with golden pubescence.
Description. The new species is similar to T. baishanzuensis sp. nov. except for the following characters: pronotum reddish along posterior margin, elytra reddish at base, abdominal segments with posterior margin reddish, legs reddish yellow without dark markings, although indistinct dark markings may be present near base of profemora; abdominal tergite VI with larger median golden tomentose patch, reaching posterior  margin of tergite, pair of dark tomentose spots very small; abdominal tergite VII completely covered with golden pubescence.
Female. Sternite VIII with posterior margin entire. Distribution. China (Fujian). Etymology. The species is named after the golden pubescence of abdominal tergite VII.
Key to Chinese species of Thoracostrongylus