On the taxonomy and zoogeography of Paederus . VI. Two new species from Nepal and new records from the Palaearctic and Oriental regions (Coleoptera: Staphylinidae: Paederinae)

Two micropterous species of Paederus Fabricius, 1775 from East Nepal are described and illustrated: Paederus (incertae sedis) digitalis spec. nov. and P. (incertae sedis) acifer spec. nov. They are distinguished from other micropterous and geographically close congeners. Including the new species, the Paederus fauna of Nepal currently includes 37 species, 24 of them exclusive. Additional records of two widespread species are reported from the Chinese province Yunnan and from Vietnam.


Introduction
Paederus Fabricius, 1775 currently includes more than 530 species worldwide (Newton 2019). It is represented in the Palaearctic region by 129 species in eight subgenera, with 45 of the species listed as incertae sedis (Schülke & Smetana 2015, Assing 2017, 2020, Willers 2018. According to the Palaearctic Catalogue (Schülke & Smetana 2015 and updates until the end of 2020), the Paederus fauna of Nepal previously included 35 species, 13 of them more or less widespread in the southern East Palaearctic and Oriental regions and 22 exclusive to Nepal. The majority (24 species, nearly all of them endemic) of the species recorded from Nepal is currently listed as incertae sedis; five are assigned to the subgenus Eopaederus Scheerpeltz, 1957, one to Heteropaederus Scheerpeltz, 1957, one to Nepalopaederus Scheerpeltz, 1976, one to Oreinopaederus Scheerpeltz, 1976 to the nominal subgenus, and one to Poederomorphus Gautier des Cottes, 1862. Nearly half of the species known from Nepal (17 species, all of them endemic) were described by Willers (1999Willers ( , 2001aWillers ( , b, 2016Willers ( , 2018. Willers (2018) provided a key to species. Only recently, Joachim Willers (Berlin) informed me that he had examined material representing an undescribed species from East Nepal forwarded to him by Michael Schülke (Berlin). Since, owing to other obligations, he did not have the time for an adequate description, he invited me to study the specimens. A closer examination eventually revealed that the material in fact included two undescribed species. Their descriptions are provided in this paper, together with a few additional records studied since the latest contribution to the taxonomy and zoogeography of Paederus (Assing 2020).

Material and methods
The material treated in this study is deposited in the following public institutions and private collection: The morphological studies were conducted using Stemi SV 11 (Zeiss) and Discovery V12 (Zeiss) microscopes, and a Jenalab compound microscope (Carl Zeiss Jena). The images were created using digital cameras (Axiocam ERc 5s, Nikon Coolpix 995), as well as Labscope and Picolay software. Body length was measured from the anterior margin of the labrum to the posterior margin of tergite VIII, the length of the forebody from the anterior margin of the labrum to the posterior margin of the elytra, head length from the anterior margin of the frons to the posterior constriction of the head, head width across and including the eyes, elytral length at the suture from the apex of the scutellum to the posterior margin of the elytra, and the length of the aedeagus from the apices of the parameres to the base of the aedeagal capsule. The "parameral" side (i.e., the side where the sperm duct enters) is referred to as the ventral, the opposite side as the dorsal aspect. According to Schülke & Smetana (2015) and Newton (2019), P. nigripennis has been recorded from North India, Nepal, the Chinese island Hainan, and the "Oriental" region (without further specification). The above male represents the first confirmed record from Vietnam.

Etymology:
The specific epithet (Latin, adjective: of the finger) alludes to the finger-shaped apical process of the internal sclerite of the aedeagus.  Fig. 1. Colouration: head and abdomen black; pronotum red; elytra black with bluish hue; legs pale-reddish; antennae and maxillary palpi yellow. Head transverse, approximately 1.15 times as broad as long, broadest across eyes, tapering behind eyes; postocular region weakly convex; punctation moderately sparse and moderately coarse. Eyes slightly more than half as long as distance from posterior margin of eye to posterior constriction of head in dorsal view. Antenna 3.6-3.7 mm long; all antennomeres distinctly oblong. Labrum with broadly concave anterior margin, in the middle with weakly produced, obtuse projection. Mandibular teeth very stout and apically bifid. Pronotum approximately 1.1 times as long as broad and 0.95 times as broad as head, laterally not margined; punctation sparse; midline broadly impunctate. Elytra short, approximately 0.65 times as long as pronotum, distinctly widened posteriad; humeral angles practically obsolete; punctation coarse and dense. Hind wings completely reduced. Protarsomeres I-IV dilated, without appreciable sexual dimorphism. Metatarsomere I shorter than the combined length of metatarsomeres II and III. Abdomen broader than elytra; punctation moderately coarse, rather dense on anterior tergites, gradually becoming sparser towards posterior tergites; interstices with microsculpture composed of transverse striae and long transverse meshes; posterior margin of tergite VIII without palisade fringe; tergite VIII posteriorly acute.
Comparative notes: Among the micropterous and similarly coloured Paederus species known from East Nepal, the aedeagus of P. digitalis most resembles that of P. tibetanus Cameron, 1928, which differs from the new species by a broader aedeagus with a shorter (not reaching apices of parameres) and apically more acute dorsal plate, an apically broadly truncate ventral process, and stouter parameres. For characters separating P. digitalis from the similar and sympatric P. acifer see the comparative notes in the following section.

Etymology:
The specific epithet (Latin, adjective: carrying a needle) alludes to the needle-shaped apical process of the internal sclerite of the aedeagus.
Comparative notes: Paederus acifer is distinguished from the similar and syntopic P. digitalis by smaller body size and a significantly smaller aedeagus with an apically more acute dorsal plate, an apically more acute ventral process, and a more slender internal sclerite with a longer, more slender, and apically more acute apical process.

Distribution:
The type locality is identical to that of P. digitalis.