Paederus (Megalopaederus) nigricrus, Assing, 2017

Assing, Volker, 2017, Two new species and additional records of micropterous Paederus from China and Taiwan (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 49 (1), pp. 253-263 : 259-262

Paederus (Megalopaederus) nigricrus nov.sp. ( Figs 18-31 )

T y p e m a t e r i a l: Holotype 3: " TAIWAN, Taitung Hsien, Hsinkangshan above Chengkung 850 m 26.IV.1995, A. Smetana [ T166 ] / Holotypus 3 Paederus nigricrus sp.n. det. V. Assing 2016" (cSme) . Paratypes: 1♀: same data as holotype (cAss) ; 1♀: same data, but " 800 m, 27.IV.1995 ... [ T168 ]" (cSme) ; 1♀: " TAIWAN, Taitung Hsien, Hsinkangshan above Chengkang [sic] 800 m 18.IV.1998 A. Smetana [ T183 ]" (cSme) ; 1♀: " TAIWAN, Taitung Hsien, Hsinkangshan above Chengkang [sic] 800 m 18.IV.1998 A. Smetana [ T183 ]" (cSme) ; 1♀: " TAIWAN, Taitung Hsien, Hsinkangshan above Chengkang 900 m 19.IV.1998 A. Smetana [ T184 ]" (cSme) ; 13, 2♀♀ [1♀ partly eaten by Anthrenus sp.]: " TAIWAN, Taitung Hsien, Hsinkangshan above Chengkang 750 m 21.IV.1998 A. Smetana [ T185 ]" (cSme, cAss) ; 1♀: " TAIWAN, Taitung Hsien, Hsinkangshan above Chengkang 550-600 m 22.IV.98 A. Smetana [ T187 ]" (cSme) ; 733, 8♀♀ [3 exs. partly eaten by Anthrenus sp.]: " TAIWAN, Taitung Hsien, Hsinkangshan above Chengkang 800 m 17-22.IV.98 Lise Robillard [ T188 ]" (cSme, cAss) .

E t y m o l o g y: The specific epithet is a noun in apposition composed of the Latin adjective niger (black) and the Latin noun crus (leg). It alludes to the completely black femora and tarsi.

D e s c r i p t i o n: Body length 8.5-12.0 mm; length of forebody 4.5-5.2 mm. Coloration: head black; pronotum red; elytra metallic-blue; scutellum red to dark-brown anteriorly and blackish posteriorly; abdomen black except for the yellowish basal halves of segments IX and X; legs black with brown tarsi; antennae blackish with the apical 3-5 antennomeres reddish to brown; maxillary palpi black with the apical palpomere yellowish to pale-brown.

Head ( Fig. 18 ) transverse, 1.12-1.20 times as broad as long; punctation moderately sparse and moderately coarse, only slightly sparser in median dorsal portion; interstices without microsculpture. Eyes 0.5-0.6 times as long as distance from posterior margin of eye to posterior constriction of head. Antenna ( Fig. 19 ) 3.2-3.8 mm long. Labrum with distinctly concave anterior margin, with a semicircular to U-shaped median incision, with a broad lateral projection on either side, and with a small projection on either side of the median incision; mandibles each with bifid molar tooth of similar shape.

Pronotum ( Fig. 18 ) 0.95-1.03 times as broad as long and 1.02-1.08 times as broad as head, strongly convex in cross-section; punctation moderately dense and moderately coarse; midline broadly impunctate.

Elytra ( Fig. 18 ) 0.55-0.59 times as long as pronotum and of trapezoid shape; humeral angles obsolete; punctation coarse, dense, and somewhat ill-defined; interstices without microsculpture. Hind wings completely reduced. Protarsomeres I-IV with moderate sexual dimorphism. Mesotibiae with dense yellowish setae apically ( Fig. 20 ); metatarsomere I approximately as long as, or slightly longer than the combined length of metatarsomeres II and III.

Abdomen ( Fig. 21 ) broader than elytra; punctation moderately coarse and moderately dense; pubescence long and black; interstices with fine microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII with pronounced sexual dimorphism.

3: protarsomeres I-IV distinctly dilated; tergite VIII ( Fig. 27 ) with strongly convex posterior margin; sternite VII without clusters of setae, with an impunctate patch in the middle, and with a broadly concave posterior margin; sternite VIII ( Fig. 28 ) with deep posterior excision, its depth 0.55-0.60 times the length length of sternite; tergites IX-X as in Fig. 26 ; aedeagus ( Figs 23-25 , 29 ) 2.3-2.6 mm long; ventral process short, with pronounced median excision, and with an acute process on the left (ventral view); parameres of similar shape and length, apically abruptly narrowed; dorsal plate strongly sclerotized and strongly asymmetric, with three conspicuous apical processes, the left one stout and strongly curved, the median one acute and the right one of similar length, acute, and weakly curved; internal sac without spines.

♀: protarsomeres I-IV distinctly dilated, but less so than in male; posterior margin of tergite VIII truncate ( Fig. 30 ); sternite VIII ( Fig. 31 ) oblong, posterior margin broadly, triangularly produced; segments IX-X as in Fig. 22.

C o m p a r a t i v e n o t e s: Paederus nigricrus is somewhat intermediate between the two previously identified species groups of Megalopaederus in Taiwan (see ASSING 2015a) It shares the moderately slender antennae and the absence of clusters of dense setae on the male sternite VII with the species of the P. formosanus group, which includes 15 described species. However, based on the red pronotum without microsculpture, the absence of setae in the median portion of the male sternite VII, the absence of spines in the internal sac of the aedeagus, as well as on the habitat (relatively low altitudes), P. nigricrus is assigned to the P. kosempoensis group, which previously com prised three described species. The new species is distinguished from all its congeners by the morphology of the aedeagus, particularly the conspicuous apical processes of the dorsal plate, from the species of the P. formosanus group additionally by a reddish pronotum without microsculpture, and from the species of the P. kosempoensis group by less slender antennae, the chaetotaxy of the male sternite VII, completely black femora, and the coloration of the abdominal segments IX-X.

In order to account for P. nigricrus , the key to the Megalopaederus species of Taiwan in ASSING (2015a) is modified as follows:

2. Head and pronotum without trace of microsculpture, glossy ............................................2a

- Head and pronotum at least with shallow microsculpture and with more or less reduced shine ....................................................................................................................................5

2a. Antennae less slender; antennomeres IV–VIII approximately three times as long as broad ( Fig. 19 ). Femora completely black. Male sternite VII without clusters of dense setae. Dorsal plate of aedeagus with three apical processes of distinctive shapes ( Figs 23-25 , 29 ) ........................................................................................................... P. nigricrus

- Antennae conspicuously slender; antennomeres IV–VIII distinctly more than three times as long as broad ( ASSING 2015a: figures 53-55). Femora basally yellowish. Male sternite VII with a of cluster of dense setae on either side of middle ( ASSING 2015a: figures 204, 207); aedeagus with broad and apically not elongated dorsal plate.................3

D i s t r i b u t i o n a n d n a t u r a l h i s t o r y: Thespecimenswerecollected in several close localities in the Hsinkangshan, Taitung Hsien, Taiwan. The altitudes range from approximately 550 to 900 m.

Figures

Figs 18-26: Paederus nigricrus nov.sp.: (18) forebody; (19) antenna; (20) mesotibia; (21) abdomen; (22) female segments IX-X; (23-25) aedeagus in ventral, lateral, and dorsal view (in dry preparation); (26) male segments IX-X. Scale bars: 1.0 mm.

Figs 27-31: Paederus nigricrus nov.sp.: (27) male tergite VIII; (28) male sternite VIII; (29) aedeagus in ventral view in transparent light; (30) female tergite VIII; (31) female sternite VIII. Scale bars: 1.0 mm.