A revision of Neosclerus V. Thirteen new species and additional records (Coleoptera: Staphylinidae: Paederinae)

Thirteen species of Neosclerus Ca m ero n , 1924 are described and illustrated: N. albens spec. nov. (Sri Lanka), N. areolatus spec. nov. (Thailand), N. biangulatus spec. nov. (Thailand), N. daweianus spec. nov. (China: Yunnan), N. discolor spec. nov. (Burma, Thailand), N. figens spec. nov. (China: Yunnan), N. forficatus spec. nov. (Sri Lanka), N. fractus spec. nov. (India: Meghalaya), N. khasicus spec. nov. (India: Meghalaya), N. revolutus spec. nov. (South India), N. sagittatus spec. nov. (India: Meghalaya), N. semicalvus spec. nov. (Thailand), and N. trisinuatus spec. nov. (China: Yunnan). The previously unknown male sexual characters of N. granulicollis Ca m ero n , 1924 are described and illustrated. Addi­ tional records of twelve named and three unnamed species are reported, among them several new country records. The genus now comprises 44 named species in five species groups, one of them newly established. The countries with the greatest diversity are China, India, and Thailand (ten species each), and Taiwan (nine locally endemic species). The distribution of the genus as a whole, as well as the individual distributions of 34 species are mapped. An updated catalogue is provided.


Introduction
The distribution of the medonine genus Neosclerus Ca m e r o n , 1924 includes the southern East Palaearctic and the Oriental regions, and ranges from the Himalaya (North India, Nepal, Bhutan), Burma, and southern China in the north to South India, Sri Lanka, Borneo, Java, and Sumatra in the south. The genus previously included a total of 31 species.The regions with the greatest diversity were Taiwan (nine species) and southern China (seven species). A catalogue and a key to species were provided by Assing (2011a). The species have been attributed to four species groups, with some species of uncertain affili ations (male sexual characters unknown) (A ssin g 2011a, 2011b, 2013, 2014). The present paper is based on material collected during a recent field trip to East Yunnan conducted by Michael Schülke and the author, as well as on more than 500 previously unrevised specimens from the Muséum d'Histoire Naturelle, Genève. A study of this material, in total 651 specimens, yielded an astounding thirteen species new to science, the previously unkown male of N. granulicollis C a m e r o n , 1924, as well as additional records of twelve previously described species and records of three unnamed species, at least one of them undescribed.

M aterial and methods
The material treated in this study is deposited in the following collections: MHNG Muséum d'Histoire Naturelle, Genève (G. Cuccodoro) MNHUB Museum für Naturkunde der Humboldt Universität Berlin (J. Frisch, J. Willers) cAss author's private collection cSch private collection Michael Schülke, Berlin The morphological studies were conducted using a Stemi SV 11 microscope (Zeiss Germany) and a Jenalab compound microscope (Carl Zeiss Jena). The images of the forebodies were created using a photographing device constructed by Arved Lompe (Nienburg) and CombineZ software. A digital camera (Nikon Coolpix 995) was used for the remaining photographs. The maps were created using MapCreator 2.0 (primap) software. Body length was measured from the anterior margin o f the mandibles (in resting position) to the abdomi nal apex, the length o f the forebody from the anterior margin o f the mandibles to the posterior margin of the elytra, head length from the anterior margin of the frons to the posterior constriction of the head, elytral Map 1: Pooled distribution of Neosclerus in the Oriental and southern East Palaearctic regions, based on examined records.

General remarks
Including the newly described species, Neosclerus now comprises a total of 44 species in five species groups. One of them, the N. granulicollis group, is newly established with N. granulicollis as the sole representative. The general distribution of the genus (Map 1) still shows some evident gaps, particularly in the central and southern parts of India, in the southern Indochinese Peninsula, in Malaysia, and in Indonesia. Most Neosclerus species are fully winged, more or less widespread (though partly known only from few localities), and their distributions often overlap. At least three species are wing-dimorphic. Micropterous, locally endemic species are known from Northeast India (Meghalaya), South China, and particu larly from Taiwan, where macropterous species are apparently absent. The countries with the greatest diversity are China, Thai land, and India (ten species each), followed by Taiwan (nine locally endemic species), Burma (five species), Laos and Nepal (four species each), Sri Lanka (three endemic species), Malaysia (three species), Indonesia (two species), and Bhutan, Vietnam, and Hongkong (one species each).
length at the suture from the apex o f the scutellum to the posterior margin of the elytra (at the suture), and the length o f the aedeagus from the apex of the ventral process to the base o f 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.

Etymology:
The specific epithet is the past participle of the Latin verb revolvere (to roll, to coil) and alludes to the basally coiled internal structures of the aedeagus.
Description: Body length 3.1-3.9 mm; length of fore body 1.8-2.0 mm. Coloration: head and pronotum blackish; elytra and abdomen brown to blackish-brown; legs yellowish; antennae reddish to reddish-brown. Head ( Fig. 1) relatively weakly transverse, 1.07-1.10 times as broad as long; punctation coarse and dense in anterior portion, distinctly less dense to very sparse and moder ately coarse to fine in posterior portion of dorsal surface; interstices without microsculpture. Eyes separated from posterior angles by a distance of distinctly more than the width of antennomere II. Antenna approximately 1.0 mm long. Pronotum ( Fig. 1) 1.05-1.10 times as long as broad and about 0.85 times as broad as head; punctation coarse and moderately dense; midline broadly impunctate; inter stices without microsculpture. Elytra ( Fig. 1) approximately as long as pronotum; punctation rather coarse and very dense. Hind wings present.
Metatarsomere I nearly as long as the combined length of II and III. Abdomen narrower than elytra; punctation fine, moder ately dense on anterior tergites, gradually becoming sparser towards posterior tergites; interstices with distinct microsculpture; posterior margin of tergite VII with pali sade fringe. S : sternite V II (Fig. 2) approximately 1.2 times as broad as long, posterior margin broadly and distinctly concave, pubescence unmodified; sternite V III (Fig. 2) distinctly oblong and with unmodified pubescence, posterior exci sion of broadly triangular shape, its depth approximately one-seventh the length of sternite; aedeagus (Figs 4 -5 ) 0.65-68 mm long (approximately 0.6 mm in dry prepara tion) and rather weakly sclerotized; ventral process long and slender, apically hooked in lateral view; internal sac with a pair of long series of weakly sclerotized structures. Head (Fig. 6) relatively weakly transverse, approximately I . 1 times as broad as long; punctation moderately coarse and moderately dense in anterior half, sparser and less coarse in posterior half of dorsal surface; interstices with out microsculpture. Eyes separated from posterior angles by a distance of slightly more than width of antennomere II. Antenna approximately 0.75 mm long. Pronotum (Fig. 6) approximately as broad as long and about 0.85 times as broad as head; on either side of the broadly impunctate midline with a series of approxi mately 10 punctures, lateral portion with rather sparse coarse punctation; interstices without microsculpture. Elytra (Fig. 6) relatively short, approximately 0.9 times as long as pronotum; punctation moderately fine and moderately dense. Hind wings completely reduced.
Metatarsomere I nearly as long as the combined length of II and III. Abdomen approximately as broad as elytra; punctation fine, rather dense on anterior tergites, gradually becom ing less dense towards posterior tergites; interstices with shallow microsculpture; posterior margin of tergite VII with palisade fringe. ? : sternite V II (Fig. 7) 1.23 times as broad as long, posterior margin weakly concave in the middle, pubes cence unmodified; sternite V III (Fig. 8) weakly oblong and with unmodified pubescence, posterior excision of triangular shape, its depth approximately one-fifth the length of sternite; aedeagus (Figs 9-10) 0.45 mm long and weakly sclerotized; ventral process long and slender, apically acute in ventral view; internal sac with a pair of series of weakly sclerotized structures and with a basal pair of weakly sclerotized sclerites (Fig. 11).
Comparative notes: Based on external (head weakly transverse; head moderately bulging and clearly not reaching posterior angles; punctation of forebody moder ately dense) and the male sexual characters (sternites VII and V III with unmodified pubescence; aedeagus with dorso-ventrally flattened ventral process; internal sac with two long series of membranous structures and a pair of basal sclerites), N. forficatus is closely allied to N. nigerrimus (K r a a tz, 1859), previously the sole representative of the genus known from Sri Lanka. The new species is distinguished from N. nigerrimus by the much more slen der and apically more acute ventral process, as well as the more or less sclerotized and differently shaped pair of basal internal structures of the aedeagus. The unmodified pubescence of the male sternite V III and the morphology of the aedeagus (ventral process dorso-ventrally flattened; internal sac with a pair o f series of membranous structures) suggest that both N. niger rimus and N. forficatu s belong to the N. fortepunctatus group.

Distribution and natural history:
The type locality is situated in the southeast of Sri Lanka (Map 2) at an alti tude of 300 m. Description: Small species; body length 2.7-3.0 mm; length of forebody 1.5-1.6 mm. External characters ( Fig. 12) as in N. forficatus, except as follows: Head ( Fig. 12) anteriorly with relatively sparse and coarse punctures, punctation of pronotum and of remainder of head not particularly coarse and rather sparse. Elytra apparently dimorphic, approximately 1.1 times as long as pronotum in holotype (macropterous morph) and 0.9 times as long as pronotum in paratypes (brachypterous morph). Hind wings probably fully developed in macropterous morph, of reduced length (extending slightly beyond posterior margin of elytra) in brachypterous morph. ? : sternite V II (Fig. 13) 1.28 times as broad as long, posterior margin very weakly concave in the middle, pubescence sparse and unmodified; sternite V III (Fig. 14) 1.1 times as long as broad and with unmodified pubes cence, posterior excision of triangular shape, its depth approximately one-sixth the length of sternite; aedeagus (Figs 15-16) 0.45 mm long and weakly sclerotized; ventral process long and slender, apically moderately acute in ventral view; internal sac with a pair of series of weakly sclerotized structures and with a basal pair of weakly sclerotized sclerites.
Comparative notes: This species, too, is closely allied to N. nigerrimus, as can be inferred from the similar exter nal and male sexual characters. It is distinguished from N. nigerrimus by the less broad posterior excision of the male sternite VIII, the more slender ventral process of the aedeagus (N. nigerrimus: distinctly dilated subapically in ventral view) and by the weakly sclerotized and differ ently shaped basal internal structures of the aedeagus. For illustrations of N. nigerrimus see A ssin g (2011a).

Distribution and natural history:
The type locality is situated in Central Province, Sri Lanka (Map 2), at an altitude of 750 m.

Etymology:
The specific epithet is an adjective derived from Khasi Hills, where the species was discovered and where it is probably endemic.
Description: Body length 2.8-3.5 mm; length of forebody 1.5-1.6 mm. Coloration: body black, with the pronotum and the elytra sometimes slightly paler; legs and antennae yellowish. Head (Fig. 17) approximately 1.15 times as broad as long; punctation very coarse and dense, sparser and less coarse in posterior dorsal portion; interstices without micro sculpture. Eyes very large, nearly extending to posterior angles of head. Antenna approximately 0.9 mm long. Pronotum (Fig. 17) approximately 1.05 times as long as broad and about 0.85 times as broad as head; punctation moderately dense, slightly less coarse than that of head; interstices without microsculpture; midline broadly impunctate. Elytra (Fig. 17) short, 0.60-0.65 times as long as pronotum; punctation fine and dense. Hind wings completely reduced. Metatarsomere I approximately as long as the combined length of II and III, or nearly so. Abdomen approximately as broad as, or slightly broader than elytra; punctation fine, dense on anterior tergites, gradually becoming less dense towards posterior tergites; interstices with shallow microsculpture; posterior margin of tergite VII without palisade fringe. S : sternite VII (Fig. 18) . 10)   (2) 2 6 3 -2 8 5 Comparative notes: Based on the male primary and sexual characters, as well as on the practically identical external characters, N. fractus is closely allied to N. khasi cus, from which it differs by slightly greater body size, the more transverse male sternite V II without a pronounced median excision posteriorly and with different chaetotaxy, the more oblong male sternite V III with a deeper posterior excision, and by the larger aedeagus with a subapically strongly bent ventral process.
Distribution and natural history: The type specimens were collected in two localities near Cherrapunjee in the Khasi Hills, Meghalaya (Map 6), at altitudes of 1200 and 1700 m.
Neosclerus s a g itta tu s spec. nov.

Etymology:
The specific epithet is an adjective derived from the Latin noun sagitta (arrow) and alludes to the shape of the ventral process of the aedeagus in ventral view.
Description: Body length 3.1 mm; length of forebody 1.65 mm. External characters (Fig. 28)  Description: Body length 2.9-3.7 mm; length of fore body 1.6-1.9 mm. Coloration: head black; pronotum pale-reddish; elytra yellowish, with the sutural portion often more or less distinctly and more or less extensively infuscate; abdomen reddish, with the apex often more or less distinctly darker; legs and antennae yellowish. Head (Fig. 33) approximately 1.25 times as broad as long; punctation very coarse and dense, sparser in posterior dorsal portion; interstices without microsculpture. Eyes very large, nearly extending to posterior angles of head. Antenna approximately 1.0 mm long. Pronotum (Fig. 33) approximately as broad as long and 0.8 times as broad as head; punctation dense, similar to that of head; interstices without microsculpture; midline with narrow impunctate band of variable length. Elytra (Fig. 33) of rather variable length, 1.02-1.15 times as long as pronotum; punctation rather fine and very dense. Hind wings present. Metatarsomere I approxi mately as long as the combined length of II and III. Abdomen noticeably narrower than elytra; punctation extremely fine and dense; interstices with distinct micro sculpture; posterior margin of tergite V II with palisade fringe. 3 : sternite V II (Figs 34-35) moderately transverse, 1.15-1.20 times as broad as long, and with pubescence of variable density, posterior margin with, rarely with out, concavity of variable depth in the middle, near this concavity with a cluster of short dark setae; sternite V III (Figs 36-37) as broad as long or weakly oblong, anteri orly without process or elevation, but with sparse cluster of setae, postero-median portion depressed and largely without pubescence, posterior excision broadly V-shaped and approximately 0.2 times as deep as length of sternite; aedeagus (Figs 38-39) 0.48-0.54 mm long, with ventral process and internal structures of distinctive shapes.

Intraspecific variation:
This species is subject to rather pronounced variation not only of external characters, such as the coloration (particularly of the elytra and the abdominal apex) and the length of the elytra, but also of the chaetotaxy (pubescence moderately sparse to rather dense) and shape of the male sternite V II (posterior concavity more or less pronounced, in one male even absent; Figs 34-35), the density of the pubescence of the male sternite V III (Figs 36-37), and also the shape of the ventral process in ventral view (basally more or less distinctly narrowed).
Comparative notes: Using the key in Assing (2011a), N. discolor would key out together with N. assamensis, a species not only of similar coloration and general appear ance, but also closely related, as can be inferred from the similar modifications of the male secondary sexual charac ters and the similar morphology of the aedeagus (shapes of ventral process and of internal structures). The new species differs from N. assamensis particularly by the coloration of the elytra (N. assamensis: elytra uniformly yellowish) and by the shape of the ventral process of the aedeagus. For illustrations of N. assamensis see Assing (2011a, b).

Distribution and natural history:
The known distribu tion is confined to three localities, one in Burma and two in Thailand (Map 4). The specimens were collected at altitudes between 700 and 1500 m.

Etymology:
The specific epithet (Latin, adjective) alludes to the shape of the internal structures of the aedeagus in lateral view.
Description: Body length 2.8-3.3 mm; length of forebody 1.7 mm. Habitus as in Fig. 40. Coloration: head, pronotum, and abdomen blackish; elytra blackish-brown with the posterior margin and the humeral portions diffusely paler; legs yellowish; antennae reddish. Head (Fig. 41) approximately 1.15 times as broad as long; punctation very coarse and dense, somewhat sparser and slightly less coarse in posterior dorsal portion; interstices without microsculpture, in median dorsal portion much narrower than diameter of punctures. Eyes very large, nearly extending to posterior angles of head. Antenna approximately 0.9 mm long. Pronotum (Fig. 41) approximately 1.05 times as broad as long and 0.9 times as broad as head; punctation dense and slightly less coarse than that of head; interstices with out microsculpture. Elytra (Fig. 41) approximately as long as pronotum; punctation moderately coarse and very dense. Hind wings probably present. Metatarsomere I approximately as long as the combined length of II and III.

Etymology:
The specific epithet is the present participle of the Latin verb figere (to stab, to pierce) and alludes to the long, straight, and apically very acute ventral process of the aedeagus.
Description: Body length 2.8-3.5 mm; length of fore body 1.5-1.7 mm. Habitus as in Fig. 51. Coloration: head and abdomen blackish; pronotum and elytra dark-brown to blackish brown, with the posterior margins and the humeral portions of the elytra indistinctly and diffusely paler; legs yellowish; antennae reddish. Head (Fig. 52) 1.20-1.25 times as broad as long; punctation moderately coarse and moderately dense, rather sparse in posterior dorsal portion; interstices without microsculpture, on frons and between eyes on average approximately as broad as diameter of punctures. Eyes very large, nearly extending to posterior angles of head. Antenna 0.8-0.9 mm long. Pronotum (Fig. 52) 1.01-1.04 times as broad as long and approximately 0.85 times as broad as head; punctation similar to that of head; interstices without microsculpture. Elytra (Fig. 52) short, 0.60-0.65 times as long as pronotum; punctation moderately fine and dense. Hind wings completely reduced. Metatarsomere I approximately as long as the combined length of II and III. Abdomen broader than elytra; punctation very fine; microsculpture of tergites III-V I extremely shallow, that of tergite V II more distinct; posterior margin of tergite V II without palisade fringe. ? : sternite VII (Figs 53-54) transverse, approximately 1.15 times as broad as long, and with dense pubescence, posterior margin in the middle with sharply delimited concavity, anterior to this concavity with distinct dense cluster of strongly modified short and stout black setae; sternite V III (Figs 55-56) indistinctly oblong, postero median portion extensively depressed and without pubescence, near anterior margin with few black setae in the middle, without process or elevation, posterior exci sion narrowly V-shaped and 0.20-0.25 times as deep as sternite; aedeagus (Figs 57-58) approximately 0.6 mm long; ventral process straight, gradually tapering apicad, and apically acute; internal sac with a pair of distinctly sclerotized basal structures and a pair of dark and long membranous structures.

Comparative notes:
The male sexual characters of N. figen s are similar to those of N. brevipennis, from which the new species differs by shorter elytra (N. brevipennis: elytra at least 0.85 times as long as pronotum), the completely reduced hind wings, the absence of a palisade fringe at the posterior margin of tergite V II, the modifications of the male sternite V II (N. brevipennis: posterior margin weakly concave, but without pronounced median concavity; posterior clus ter with weakly modified setae), the less oblong male sternite V III with a narrower posterior excision, and by the morphology of the aedeagus (ventral process ventrally more or less distinctly angled at apical third and less acute in lateral view, broader in ventral view; internal structures of different shapes). For illustra tions of the external and male sexual characters of N. brevipennis see A ssin g (2011a). From the syntopic N. praeacu tus, N. fig en s is easily distinguished by the much shorter elytra, the distinctly less coarse and less dense punctation of the head and pronotum, and the absence of a palisade fringe at the posterior margin of tergite V II alone.

Distribution and natural history:
The type locality is situated on a mountain to the west of Gejiu in southeast ern Yunnan, South China (Map 6). The specimens were sifted from litter and various debris in, and at the margin of, a mixed forest at an altitude of nearly 2000 m, together with N. praeacutus. Several of the paratypes are teneral. The sex ratio is remarkably biased: only seven (16 %) in a total of 43 specimens are males.

Etymology:
The specific epithet (adjective) is derived from the name of the mountain, where the type locality is situated.
Description: Body length 3.3-4.0 mm; length of fore body 1.7-1.9 mm. Habitus as in Fig. 59. Coloration: head blackish; pronotum, elytra, and abdomen blackish-brown to blackish, with the elytra sometimes slightly paler; legs yellowish; antennae reddish. Head (Fig. 60) 1.20-1.25 times as broad as long; punctation coarse and very dense, only slightly less dense in posterior dorsal portion; interstices without micro sculpture in anterior dorsal portion and with shallow microsculpture in posterior dorsal portion, on aver age much narrower than diameter of punctures even in posterior dorsal portion. Eyes very large, nearly extend ing to posterior angles of head. Antenna approximately 1.0 mm long. Pronotum (Fig. 60) 1.02-1.04 times as broad as long and approximately 0.85 times as broad as head; punctation very dense and coarse, similar to that of head; interstices without microsculpture. Elytra (Fig. 60) short, 0.60-0.65 times as long as prono tum; punctation extremely dense, weakly defined, and rather coarse, rendering the surface matt or nearly so. Hind wings completely reduced. Metatarsomere I usually slightly shorter than the combined length of II and III. Abdomen broader than elytra; punctation very fine and rather dense; interstices with distinct transverse microsculpture; posterior margin of tergite V II without palisade fringe. ? : sternite V II (Fig. 61) transverse, approximately 1.15 times as broad as long, and with dense pubes cence, posterior margin in the middle with broad and very shallow, but distinctly delimited concavity, ante rior to this concavity with distinct cluster of modified short and stout black setae; sternite V III ( Comparative notes: Regarding its external and male sexual characters, N. daweianus is similar to N. assamensis (C a m e r o n , 1931) from Northeast India, from which the new species differs by the darker coloration, the more transverse male sternite V II with a broader and distinctly delimited posterior concavity, the less oblong male sternite V III with a more extensive depression, only few setae in the antero-median portion, and a much narrower posterior excision, and by an aedeagus with a longer ventral process pointing more strongly ventrad and with differently shaped internal structures. For illustrations of the external and male sexual characters of N. assamensis see A ssin g (2011a, 2013).

Distribution and natural history:
The type locality is situated at the foot of the Dawei Shan near Pingbian in southeastern Yunnan, South China (Map 6). The partly teneral specimens were sifted from litter in a subtropical broad-leaved forest at an altitude of 1500 m.  1993. Schwendinger" (MHNG, cAss).

Etymology:
The specific epithet (Latin, adjective: with two angles) alludes to the shape of the posterior margin of the male sternite VII.
Description: Body length 2.7-3.0 mm; length of forebody 1.7-1.8 mm. Coloration: head and pronotum dark-brown to blackish; elytra brown with slightly and diffusely paler humeral angles and posterior margins; abdomen darkbrown to blackish-brown with paler apex; legs yellow; antennae reddish-yellow. Head (Fig. 66) approximately 1.2 times as broad as long; punctation coarse and very dense, less dense in posterior dorsal portion; interstices without microsculpture. Eyes very large, nearly extending to posterior angles of head. Antenna approximately 0.9 mm long. Pronotum (Fig. 66) 1.02-1.04 times as broad as long and 0.80-0.85 times as broad as head; punctation dense and coarse, similar to that of head; interstices without microsculpture. Elytra (Fig. 66) long, approximately 1.1 times as long as pronotum; punctation dense and rather fine. Hind wings fully developed. Metatarsomere I approximately as long as the combined length of II and III. Abdomen narrower than elytra; punctation fine and moderately dense; interstices with distinct transverse microsculpture; posterior margin of tergite V II with pali sade fringe. ? : sternite V II (Fig. 84) approximately as broad as long, and with moderately dense pubescence, in postero median portion with a cluster of approximately ten short setae, posterior margin with an angular projection on either side; sternite V III (Fig. 85)  tation of the head and pronotum, the less broad male sternite V II with fewer short setae in postero-median portion and with a pair of angular projections at its posterior margin (absent in N. rougemonti), a male sternite V III with some setae along the middle in posterior portion and with a narrower posterior excision, and by the longer, more slender, and more acute apical portion of the ventral process of the aedeagus. For illustrations of N. rougemonti see A ssin g (2011a).

Distribution and natural history:
The species is currently known from Doi Inthanon and Taksin  Description: Body length 2.8-3.8 mm; length of forebody 1.7-2.0 mm. Coloration: head blackish-brown to black; pronotum brown to blackish-brown; elytra pale-brown to brown, with slightly and diffusely paler humeral angles and posterior margins; abdomen brown to blackishbrown with paler apex; legs yellow; antennae dark-yellow. Head (Fig. 69) approximately 1.25 times as broad as long; punctation coarse and very dense, only slightly less dense in posterior dorsal portion; interstices with out microsculpture. Eyes very large, nearly extending to posterior angles of head. Antenna approximately 1.0 mm long. Pronotum (Fig. 69) distinctly transverse, 1.05-1.07 times as broad as long and approximately 0.85 times as broad as head; punctation dense and coarse, similar to that of head; midline narrowly impunctate and usually with a fine median furrow in posterior half; interstices without microsculpture. Elytra (Fig. 69) 1.00-1.05 times as long as pronotum; punctation dense and rather fine. Hind wings fully devel oped. Metatarsomere I slightly shorter than the combined length of II and III.
Abdomen narrower than elytra; punctation fine and dense; interstices with shallow transverse microsculpture; posterior margin of tergite V II with palisade fringe. S : sternite VII (Fig. 70) transverse, approximately 1.15 times as broad as long, and with moderately dense pubescence, in postero-median portion with a clus ter of numerous short setae, posterior margin with an angular projection on either side, between these projec tions more or less distinctly concave; sternite V III (Figs 71-72) oblong, in posterior portion impunctate and without pubescence, except for few setae along the middle, posterior excision of narrowly triangular shape and approximately 0.2 times as deep as length of sternite; aedeagus (Figs 73-74) 0.55-0.60 mm long; ventral process straight, rather stout, weakly dentate subapically, and apically very acute; internal sac with dark membra nous structures.
Comparative notes: Based on the similar male sexual characters, N. sem icalvus is closely allied to N. rougem onti and N. biangulatus. It differs from both of them by the broader body, the more transverse pronotum, the presence o f a fine median furrow along the posterior half o f the pronotal midline, the somewhat shorter elytra, and the stouter ventral process of the aedeagus with less pronounced subapical teeth, from N. rougem onti additionally by the much denser puncta tion o f the forebody, the presence o f angular projections at the posterior margin of the male sternite V II, and the presence of few setae along the middle of the poste rior half of the male sternite V III, from N. biangulatus also by the slightly denser punctation of the forebody, the distinctly transverse male sternite V II with more numerous short setae in the postero-median portion, the deeper posterior excision o f the male sternite V III, and the larger aedeagus.

Intraspecific variation:
The male from Doi Angkhang is distinguished from those from the type locality by the slightly different shape of the male sternite V II (poste rior margin more strongly concave between the angular projections). However, no additional differences were found suggesting that it should represent a different species.
Distribution and natural history: The known distribu tion is confined to two localities in northern Thailand (Map 6). The specimens were collected at altitudes of 900 and 1500 m.

Etymology:
The specific epithet (Latin, adjective) alludes to the areolate punctation of the head and pronotum.
Description: Body length 3.2-4.0 mm; length of forebody 1.9-2.1 mm. Coloration: head blackish; pronotum darkbrown to blackish; elytra brown to blackish-brown, with the humeral angles indistinctly paler and the posterior margins usually broadly yellowish to reddish; abdomen blackishbrown to blackish; legs yellow; antennae dark-yellow. Head (Fig. 75) approximately 1.25 times as broad as long; punctation umbilicate, moderately coarse and extremely dense on whole surface, including posterior dorsal portion, rendering dorsal surface matt (Fig. 76); interstices reduced to narrow ridges everywhere, with very shallow, nearly obsolete microsculpture visible only at high magnifica tion. Eyes very large, nearly extending to posterior angles of head. Antenna approximately 1.1 mm long. Pronotum (Fig. 75) transverse, approximately 1.05 times as broad as long and 0.86-0.88 times as broad as head; punctation umbilicate, very dense, and coarse, coarser than that of head (Fig. 77); impunctate median band very narrow, often present only in posterior half, with fine but distinct furrow in posterior half; interstices very narrow, without microsculpture. Elytra approximately as long as pronotum; punctation dense and distinct. Hind wings fully developed. Metatarsomere I approximately as long as the combined length of II and III. Abdomen narrower than elytra; punctation fine and dense; interstices with shallow transverse microsculpture; posterior margin of tergite VII with palisade fringe. 5 : sternite VII (Figs 78-79) weakly transverse, approx imately 1.05 times as broad as long, and with dense pubescence, in postero-median portion with an ill-defined cluster ofslightly stouter and darker setae, posterior margin distinctly concave in the middle; sternite V III (Figs 80-81) approximately as broad as long, anteriorly with an oblong median elevation with dense setae, in posterior portion depressed, impunctate and without pubescence, except for a band of setae along the middle, posterior exci sion of triangular shape and approximately 0.25 times as deep as length of sternite; aedeagus (Figs 82-83) approxi mately 0.5 mm long; ventral process subapically abruptly narrowed and weakly curved, apically acute in lateral view; internal sac with short and stout sclerotized structures.
Comparative notes: Based on the morphology of the aedeagus (shapes of the ventral process and of the inter nal structures), as well as the similarly derived shapes and chaetotaxy of the male sternites V II and VIII, N. areo latus is closely allied to N. barbatulus, from which it differs by the distinctly broader body, the much denser and areolate punctation of the head and pronotum, the much narrower impunctate band on the pronotum, the less strongly modified pubescence in the postero-median portion and the more strongly concave posterior margin of the male sternite VII, the shape and chaetotaxy of the male sternite V III (N. barbatulus: posterior excision less deep, posterior portion without setae along the middle), and by the smaller aedeagus (N. barbatulus: approxi mately 0.55 mm) with a ventral process of different shape both in lateral and in ventral view. For illustrations of N. barbatulus see A ssin g (2011a).

Distribution and natural history:
The type specimens were found in several localities in northern Thailand at altitudes of 1250-1720 m. The material from the type locality was collected by litter sampling in a moist ever green forest. Some of the paratypes are teneral; two are infested with Laboulbeniales.