Orencostoma semicirculum Wang, 2019

Lou, Kang, Li, Juan & Wang, Shuxia, 2019, First report of the genus Orencostoma Moriuti (Lepidoptera: Yponomeutidae) from China, with descriptions of two new species, Zoological Systematics 44 (1), pp. 76-83 : 82-83

Orencostoma semicirculum Wang sp. nov. ( Figs 4 , 10 , 13)

Diagnosis. This species is similar to O. divulgatum Wang sp. nov. It can be distinguished by the semicircular sacculus, the smooth ventral plate of the gnathos, and the phallus with one cornutus in the male genitalia; the ductus bursae approximately 1.5 times of the length of the corpus bursae and the rhombic signum with dense denticles mediohorizontally in the female genitalia. In O. divulgatum Wang sp. nov., the sacculus is sub-triangular, the ventral plate of the gnathos is spinous on ventral surface, and the cornuti consist of a few relatively large spines followed by two rows of microspines; the ductus bursae is 3.0‒4.5 times the length of the corpus bursae, and the pyriform signum bears dense denticles throughtout.

Description. Adult ( Fig. 4 ) wingspan 8.0−10.0 mm. Vertex rough, white, mixed with pale brown between antennae; face smooth, creamy white mixed with pale brown. Antenna about 2/3 length of forewing, creamy white on ventral surface, dark brown annulated with creamy white on dorsal surface. Labial palpus blackish brown ventrally, white dorsally, pointed apically. Thorax and tegula creamy white, mixed with greyish brown scales. Forewing with ground color creamy white, densely covered with brown scales, forming an ill-defined blackish brown patch at middle of fold; cilia greyish white, tipped with blackish brow. Hindwing and cilia pale dim yellowish grey. Fore- and midlegs ventrally black, dorsally creamy white except tarsi blackish brown at apex of each tarsomere; hindleg creamy white, tibia with brown scales, tarsus with each tarsomere ringed with black distally.

Male genitalia ( Fig. 10 ). Uncus sub-quadrate, shallowly concave sinuate on posterior margin, produced to a short horn posterolaterally. Socius slightly widened beyond middle, then narrowed to apex, with an apical spine; dorsal margin arched, ventral margin straight. Gnathos with ventral plate short tongue shaped or triangular; lateral arms narrowed banded. Valva sub-rectangular, length 3 times of width, obliquely blunt at apex, densely setose on ventral half; costa narrow, banded; transtilla slender, more than 1/3 length of costa; sacculus very short, semicircular, densely setose. Saccus shorter than socius, subparallel or distally dilated elliptically. Phallus about 2.2 times length of valva, with microspines distally; cornutus being one stout spine, triangular basally.

Female genitalia (Fig. 13). Intersegmental membrane between papilla analis and eighth sternum wide and short. Apophyses anteriores 5/6 length of apophyses posteriores, ventral branch extended to lamella postvaginalis. Lamella postvaginalis not well-defined, very narrow, more or less V shaped. Antrum columnar, uniform; ductus bursae about 1.5 times of corpus bursae, becoming thicker from basal 1/3 toward corpus bursae, basal 1/3 smooth, distal 2/3 densely spinuous; ductus seminalis arising from near base. Corpus bursae pyriform, with granules; signum rhombic, horizontally with dense denticles along median area.

Type material. Holotype ♂, Mt. Qian , Anshan City, 5.VII.2010, coll. Jiayu Liu, Yanpeng Cai, slide No. LK 16003 . Paratypes (10♂ 5♀). Ningxia : 4♂ 4♀, Suyukou (38.5  N, 106.1  E), Mt. Helan , 2000 m, 2.VII.2006, coll. Feng Yang, Qi He, slide Nos. CPX15045 ♂, CPX15064 ♂, CPX15046 ♀, CPX15063 ♀, LK17133 ♀ W; 1♂, 3. VI.2006, coll. Xinpu Wang et al., other data same as for holotype . Hebei: 1♂, Mt. Wuling , Xinglong County, 1000 m, 16. VI.2014, coll. Shurong Liu et al., genitalia slide No. CPX15086 . Liaoning: 1♂, Mt. Qian, Anshan City , 5.VII.2010, coll. Jiayu Liu, Yanpeng Cai, genitalia slide Nos. CPX15033 . Henan: 3♂ 1♀, Baotianman , Neixiang County, 1200 m, 25‒30. V.2006, coll. Xu Zhang, Jinmei Lv, genitalia slide Nos. LK 17134 ♂, LK17134W ♂, LK17129 ♀.

Distribution. China (Liaoning, Hebei, Henan, Ningxia).

Etymology. This epithet is derived from the Latin prefix semi - and the Latin circulus, referring to the semicircular sacculus of the male genitalia.

Funding This project is supported by the National Natural Science Foundation of China (31750002).

Acknowledgements We express our thanks to Mr. Peixin Cong for dissecting some specimens, and to those who participated in the field work.

Figures

Figures 3‒4. Orencostoma spp. 3. O. divulgatum Wang sp. nov., ♂, holotype. 4. O. semicirculum Wang sp. nov., ♂, holotype. Scales bars=2.0mm.

Figures 8‒10. Male genitalia (left) and enlarged saccus (right) of Orencostoma spp. 8–9. O. divulgatum Wang sp. nov., paratype. 8. Slide No. LK16004, from Zhejiang; 9. slide No. CPX15030, from Sichuan. 10. O. semicirculum Wang sp. nov., paratype, slide No. CPX15064, from Ningxia. Scale bars: 8‒10=0.25mm; 8a‒10a =0.1mm.