Description of a new species of Distenia (Coleoptera, Disteniidae, Disteniini) from Southeastern China, with records and diagnoses of similar species

Abstract A new species, Distenia orientalis sp. n. is described from Southeastern China. It was misidentified as Distenia gracilis (Blessig, 1872) but can be separated from the latter by the color of antennae and legs, structure differences on scape, maxillary palp, pronotum, tibiae, punctures on elytra, etc. Three related species are carefully diagnosed and treated.


Figures 1-4. Distenia gracilis
. 1 male, from Far East Russia 2 female, from Far East Russia 3 male, from Liaoning, China a dorsal view b ventral view 4 female, from Liaoning, China. Scale 5 mm.
Figures 5-11. Genitalia of Distenia gracilis (Blessig, 1872). 5-9 male, from Far East Russia 5 median lobe 6 rods of endophallus 7 hair-like thin rod of ejaculatory duct 8 tegmen a ventral view b lateral view. c dorsal view 9 tergite VIII in dorsal view 10-11 female, spermathecal capsule, both from Liaoning, China. A-B from different sides. Scale 1 mm. is incorrect, as it was based on misidentification of D. orientalis sp. n. The records from Hubei and Anhui are doubtful and may also be based on misidentification of D. orientalis sp. n. (or another species) but we did not have specimens available from these We did not have specimens from Korea for study. We consider the record by Ganglbauer (1887) and Lee (1987) correct based on the pictures by Lee (1987).
The holotype of Apheles gracilis Blessig, 1872 is a male from Russia, Sibérie (Amurland), collected by P. Wulffius. It was supposed to be deposited in ZMAS. We could not reach the curators in ZMAS. According to personal communication by Mikhail Danilevsky, he could not find the type in the collection of ZMAS.  Diagnosis. According to Danilevsky (2012), Distenia gracilis Blessig, 1872 (mainland and Sakhalin) and D. japonica Bates, 1873 (islands) are different vicariant species, very easily distinguished by narrow scapus in D. japonica. Further differences are shown in Table 1.
Remarks. This species was first described by Bates (1873) based on syntypes from Japan, Honshu (Hyogo Prefecture), Maiyasan, collected by George Lewis. Kraatz (1879) synonymized it with D. gracilis, which was widely followed by subsequent authors until Danilevsky (2012) resurrected it. Švácha and Danilevsky (1987) pointed out the habit differences between the mailand population and island population, and suspected "it is possible that we are facing two separate taxa". "However, reliable larval morphological differences have  Diagnosis. According to Yokoyama (1966): "This subspecies differs from the typical species (D. japonica), in having the following points: body smaller and more blackish, sparsely covered with shorter brownish yellow pubescence, which is sparser on head and prothorax. Clypeus longer, vertex less punctured. Prothorax weakly irregularly wrinkled, lateral tubercles less developed, not acute at apex. Terminal joint of maxillary palpus rounded at apex (instead of truncate)." Remarks. This subspecies was described based on the female holotype from Japan, Ryukyu island, Mt. Miyanouradake (alt. 1200 m), collected by Hajime Yokoyama on August 3, 1962. It is deposited in Osaka Museum of Natural History. We did not examine the holotype or other specimens but followed Ohbayashi and Niisato (2007) and Danilevsky (2012) in treating this form as a subspecies.
Pronotum broadest in middle, with acute conical lateral spines, near posterior and anterior margins with slight transverse constriction, with rugae on disc, and with dense minute punctures and dense gray pubescence. Scutellum not longer than width at base, apically rounded, with yellowish pubescence.
Elytra narrow, taper uniformly toward apex, length 3.0-3.4 times the total width at humeri, and anterior half with deep punctures forming several indistinct longitudinal rows. Abdominal ventrite V in female (Figs 26b, 34d) elongate, gently rounded posteriorly; in male (figs 28b, 33d) distinctly emarginate, with minute tender closely recumbent hairs. Legs long and slender, mesotibiae (of both male and female) without apical protruding lobe.
Male terminalia (Figs 29-33): Tegmen (Fig. 32) approximately 5.0 mm in length; lateral lobes slender, length about 5 times the width, ventral side and apex with short setae; median lobe plus median struts (Fig. 29) slightly curved, longer than tegmen; the median struts less than 1/8 of the whole median lobe in length; apex of ventral plate bluntly pointed; internal sac bearing a basal armature (Fig. 29b) and two median rods of endophallus (Figs 30, 31), of which the strongly sclerotized one (coming from the gonopore) connected to a very long (much longer than the median rods) hair-like rod (inside ejaculatory duct, Fig. 30). Tergite VIII (Fig. 33) longer than broad, narrowed apically from middle, with rounded apex, apical half bearing short dorsal setae.  Female terminalia : Paraproct moderate in size, its baculi thick and long, straight and not bifurcate at base; valvifer indistinct; coxite with rough surface, each baculum very thick at base and narrowed towards apex; coxite lobes sclerotized at each inner part, with tactile hairs; stylus articulated to the tip of each coxite lobe (slightly laterally), sclerotized except for apex and bearing tactile hairs; dorsal baculi sinuate and longer than paraproct baculi; proctiger baculi long and almost straight. Spermathecal capsule (Figs 34-36) large, heavily sclerotized and of very intricate structure, its apical part narrow, strongly bent at middle and basally with a protrusion (in shape of a question mark "?"), basal part irregularly twisted and with rather broad protrusion to which attaches the spermathecal gland at the middle part. Tignum much shorter than half of abdomen. In one measured specimen, tignum was 4.4 mm for an adult with 12.0 mm abdomen length in ventral view.
Diagnosis. The differences of the three species are shown in Table 1.
Etymology. The name of the new species refers to its distribution in southeast China, instead of northeast China (which is the distribution of D. gracilis).
Remarks. This species has been misidentified as D. gracilis since Gressitt (1951). It is the 29 th recorded species for the Chinese Disteniidae fauna (Lin et al. 2010;Lin and Murzin 2012).
One female from Mt. Wutaishan of Shanxi Province shows a strange dot on the distributional map. We believe that the distribution region will be extended after further survey.