Lathrobium curvatissimum, Assing, 2013

Assing, Volker, 2013, On the Lathrobium fauna of China V. New species and additional records from Yunnan (Coleoptera: Staphylinidae: Paederinae), Beiträge Zur Entomologie = Contributions to Entomology 63 (1), pp. 53-128 : 109-111

4.4 The L. curvatissimum species group

4.4.1 Lathrobium curvatissimum sp. n.

( Figs 270-275 , Map 7 )

Type material:

Holotype ♂ [teneral]: “ CHINA: Yunnan, Dali Bai Aut. Pref., Jizu Shan, path to cable car, 37 km NE Dali , 25°58'N, 100°23'E, 2450 m, mixed forest, sifted from litter, moss & pine apples, 5.IX.2009, leg. M. Schülke [CH09-29] / Holotypus ♂ Lathrobium curvatissimum sp. n. det. V. Assing 2013” (cAss) . Paratypes: 1 ♂ [teneral]: same data as holotype (cSch) ; 2 ♀♀: “ CHINA: Yunnan province, Shanzhi env., 22.-24.VI.2007, Jizu Shan Mt. , 2180-2580 m, along the path to the summit, 27°57.7-8' N [evidently erroneous; probably 25°], 100.22.1-23.6' E, J. Hájek & J. Růžička leg. / sifted detritus and leaves, dense mixed forest (with dominant Quercus , Pinus and Rhododendron) near stream [Ch45-47]” (cSch, cAss) .

Etymology:

The specific epithet (Latin, adjective) alludes to the strongly curved ventral process of the aedeagus.

Comment:

The two females were not collected together with the males and are slightly smaller. Nevertheless, they are hypothesized to be conspecific based on the otherwise similar external characters. Sexual size dimorphisms are not uncommon among the Lathrobium species of China (ASSING in press a). Lathrobium celere , too, is subject to a pronounced sexual dimorphism (ASSING 2013)

Description:

Species of moderate size, apparently with sexual size dimorphism; body length 7.3-7.8 mm (♂♂), 6.7-7.3 mm (♀♀); length of forebody 3.9-4.0 mm (♂♂), 3.4-3.8 mm (♀♀). Coloration: body black; legs and antennae reddish.

Head ( Fig. 270 ) approximately as long as broad or weakly oblong; punctation moderately coarse and moderately dense, somewhat sparser in median dorsal portion; interstices with very shallow microreticulation and somewhat glossy. Eyes moderately small, approximately one third the length of postocular region in dorsal view and composed of approximately 40-50 ommatidia. Antenna 1.9- 2.2 mm long.

Pronotum ( Fig. 270 ) approximately 1.3 times as long as broad and 1.05 times as broad as head; punctation similar to that of head; interstices without microsculpture and glossy; impunctate midline moderately broad, somewhat irregular.

Elytra ( Fig. 270 ) approximately 0.52 times as long as pronotum and rather slender; punctation rather dense and fine. Hind wings completely reduced. Protarsi with pronounced sexual dimorphism.

Abdomen slender, only slightly broader than elytra; punctation fine and very dense; interstices with shallow microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII without appreciable sexual dimorphism, posterior margin weakly convex.

♂: sternites III-VI unmodified; sternite VII ( Fig. 271 ) moderately transverse, symmetric, with shallow median impression posteriorly, pubescence very weakly modified, posterior margin broadly and weakly concave, anterior margin without median process; sternite VIII ( Fig. 272 ) symmetric, moderately transverse, posteriorly with weakly modified black setae, posterior margin very weakly concave in the middle; aedeagus ( Fig. 273 ) approximately 1.6 mm long, symmetric; ventral process conspicuously long, slender, and strongly curved in lateral view; dorsal plate straight in lateral view; internal sac with pair of relatively slender, broad-based, and apically acute spines.

♀: sternite VIII ( Fig. 274 ) approximately 1.2 mm long, distinctly oblong, and convexly produced posteriorly; tergite IX ( Fig. 275 ) with long and undivided median portion without suture, and with moderately long postero-lateral processes; tergite X ( Fig. 275 ) flat, slightly shorter than antero-median portion of tergite IX.

Comparative notes:

Lathrobium curvatissimum is readily distinguished from the syntopic L. jizushanense by the distinctly more slen- der pronotum, the more slender elytra, the different shapes of the male sternites VII and VIII, the much more oblong female sternite VIII, the anteriorly much longer and undivided antero-median portion of the female tergite IX, the flat and much shorter female tergite X, and particularly by the completely different morphology of the aedeagus. It differs from the sympatric L. zhangi by larger size and by the different morphology of the aedeagus. For illustrations of L. jizushanense and L. zhangi see Figs 56-63 and WATANABE & XIAO (1997).

Distribution and natural history:

Lathrobium curvatissimum was collected in two geographically close localities in the Jizu Shan, to the northeast of Dali ( Map 7 ). The specimens were sifted from leaf litter in mixed forests at an altitude of 2180-2580 m, together with L. jizushanense . The two male types are teneral .

4.4.2 Lathrobium yinae WATANABE & XIAO, 1997 ( Figs 276-282 , Map 7 )

Material examined:

China: Yunnan: 2 ♂♂, 1 ♀, 35 km N Lijiang, Heishui , 27°13'N, 100°19'E, 18. VI.-4.VII.1993, leg. S. Becvar ( NHMW, cAss) ; 1 ♂ [teneral], 1 ♀, 50 km N Lijiang ,

Yulongxue Shan Nature Reserve , 24.-29.VI.1993, leg. Jendek & Sausa ( NHMW, cAss); 1 ♀, Lijiang Naxi Aut. Co., 30 km N Lijiang , E Yulongxue Shan, 27°09.0'N 100°14.9'E, 2800-2900 m, 13.VIII.2003, leg. Smetana (cSme) .

Comment:

The original description is based on a male holotype and two paratypes (a teneral male and a female) from “Mt. Yulongxue Shan, Lijiang Xian” ( WATANABE & XIAO 1997). The measurements of the body and the forebody (“6.5-7.0 mm” and “ 2.9-3.1 mm ”, respectively) indicated in the description, as well as the scale provided with the drawings of the aedeagus (suggesting a length of 0.9 mm) are undoubtedly inaccurate. According to photos of a non-type male of L. yinae from the Yulonxue Shan sent to me by Zhong Peng, which are in complete agreement with the illustrations provided by WATANABE & XIAO (1997), the aedeagus of that particular specimen is 2.4 mm long.

The aedeagus of the examined material is 2.2-2.3 mm long and has the ventral process somewhat more strongly curved in lateral view than illustrated in the original description and in the photo of the non-type male. However, additional differences were found neither in external characters (photo of the habitus of the holotype examined), nor in the shapes and chaetotaxy of the male sternites VII and VIII (based on a comparison with the original description and with photos of the additional male). Therefore, the observed differences in the shape of the ventral process of the aedeagus are attributed to intrarather than interspecific variation.

Description:

Species of rather large size; body length 8.5-10.0 mm; length of forebody 4.5-4.9 mm. Habitus as in Fig. 276 . Coloration: body black; legs and antennae dark-reddish to brown.

Head ( Fig. 277 ) 1.00-1.05 times as broad as long; punctation moderately coarse and rather dense, somewhat sparser in median dorsal portion; interstices with fine microreticulation. Eyes moderately small, approximately 0.4 times as long as postocular region in dorsal view and composed of> 50 ommatidia. Antenna 1.9- 2.1 mm long.

Pronotum ( Fig. 277 ) approximately 1.3 times as long as broad and 1.05 times as broad as head; punctation similar to that of head; interstices without microsculpture and glossy; impunctate midline moderately broad.

Elytra ( Fig. 277 ) approximately 0.53 times as long as pronotum and not particularly broad; punctation rather dense and fine. Hind wings completely reduced. Protarsi with moderately pronounced sexual dimorphism.

Abdomen approximately 1.15 times as broad as elytra; punctation fine and very dense; interstices with shallow microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII without sexual dimorphism, posterior margin weakly convex.

♂: sternites III-VI unmodified; sternite VII ( Fig. 278 ) distinctly transverse, symmetric, with shallow median impression posteriorly, pubescence very weakly modified, posterior margin broadly and weakly concave, anterior margin with minute median process; sternite VIII ( Fig. 279 ) symmetric, weakly transverse, with pair of oblong clusters of moderately modified, very dense black setae in posterior half, posterior margin convex, in the middle very weakly concave; aedeagus ( Fig. 280 ) 2.2- 2.3 mm long, symmetric, and with small basal portion; ventral process long, slender, and smoothly curved in lateral view; dorsal plate with very long, slender, apically acute, basally strongly curved, and distinctly sclerotized apical portion, and with minute basal portion; internal sac with long dark membranous structures.

♀: sternite VIII ( Fig. 281 ) approximately 1.6 mm long, distinctly oblong, and with strongly convex posterior margin; tergite IX ( Fig. 282 ) slender, with rather short antero-median portion without median suture, and with conspicuously long and straight postero-lateral processes; tergite X ( Fig. 282 ) very long and slender, moderately convex in cross-section, apically acute, and approximately five times as long as antero-median portion of tergite IX.

Comparative notes:

The similar morphology of the aedeagus (long and curved ventral process; long apical portion of dorsal plate) and the similar shapes of the male sternite VIII and of the female tergite IX (slender shape; antero-median portion undivided, without suture), as well as the similar external appearance suggest that L. yinae is affiliated to L. curvatissimum , from which it differs by distinctly larger size, larger eyes, and the sexual characters.

Distribution and natural history:

Lathrobium yinae was collected in several geographically close localities in the Yulongxue Shan, to the north of Lijiang. One of the examined specimens was found at an altitude of 2800-2900 m; the labels of the remaining specimens do not indicate any altitudes. One of the specimens collected in June is teneral.

Figures

Map 7: Distribution of the species of the L. lijiangense (filled star), the L. celere (other filled symbols), the L. squamosum (open star), and the L. curvatissimum (other open symbols) (sub-)groups: L. seriespinosum and L. sexspinosum (black star); L. squamosum (white star); L. glandulosum (black circles); L. acre (black triangle); L. incurvatum (white diamond); L. stipiferum (white circles); L. yinae (white triangles); L. curvatissimum (white square).

Figs 270-282: Lathrobium curvatissimum (270-275) and L. yinae (276-282): forebody (270, 277); male sternite VII (271, 278); male sternite VIII (272, 279); aedeagus in lateral view (273, 280); female sternite VIII (274, 281); female tergites IX-X (275, 282); habitus (276). Scale bars: 270, 276-277: 1.0 mm; 271-275, 278-282: 0.5 mm.

Figs 56-63: Lathrobium jizushanense: habitus (56); forebody (57); male sternite VII (58); male sternite VIII (59); aedeagus in lateral and in ventral view (60-61); female sternite VIII (4); female tergites IX-X (63);. Scale bars: 56-57: 1.0 mm; 58-63: 0.5 mm.