Arbomia trigonoprocessa Jiang, Xue & Han, 2014

Jiang, Nan, Xue, Dayong & Han, Hongxiang, 2014, A new species of Arbomia Sato & Wang (Lepidoptera, Geometridae, Ennominae) from Guangxi, Southern China, Zootaxa 3765 (1), pp. 98-100 : 98-100

Arbomia trigonoprocessa Jiang, Xue & Han sp. nov.

Figs 1, 2, 5, 6

Description. Head. Antenna with white scales dorsally, about two-fifths length of forewing, bipectinate, tapering, very shortly bipectinate in female. Frons black, not protruding. Labial palpus greyish black, not extending beyond frons. Vertex pale grey. Thorax. Patagium black. Tegula black, mixed with greyish white scales at both ends and at middle. Metanotum black, with white scales at two sides and at posterior end. Hind tibia not dilated, with two pairs of spurs in both sexes, without hair-pencil. Forewing length: male 20–22 mm; female 23 mm. Forewing outer margin straight, hindwing rounded. Wings white tinged with pale yellowish brown, densely covered with black scales. Forewing with antemedial line black, double and wavy; medial line black, protruding outwards among M veins; discal spot black and rounded; postmedial line black, dentate, protruding outwards between costa and M 3, strongly incurved below M 3, meeting medial line between CuA 2 and 2A; an indistinct black band present outside postmedial line; submarginal line white and serrate; a row of black dots present inside submarginal line; terminal line present as a series of short black strips between veins; fringes yellowish brown, interrupted at veins by black scales. Hindwing with medial line wavy; discal spot smaller and less distinct than that of forewing; postmedial line double and dentate; other striations similar to those of forewing. Underside with discal spots distinct, present as black short strip, other striations less distinct than those on upperside. Forewing with a basal fovea in male; Sc, R 1 and R 2 separate. Abdomen. Abdominal segments yellowish brown mixed with black scales. Third sternite of male abdomen with a setal comb. Male genitalia. Uncus almost triangular, square and shallowly bifurcate at apex, with an elliptical dorsal process that bearing long setae. Gnathos with a small, acute apically median process. Valva narrow at terminal half, rounded apically; costa sclerotized, almost straight, with setae at terminal half; a sclerotized band extending from middle of inner side of costa to apex of sacculus, a short digitiform process with short spines formed on inner surface of apex of sacculus; saccus semicircle; juxta bifid at apical two fifth, and forming a rounded concavity; aedeagus short and stout, with a triangular process posterior; vesica partly sclerotized, with 6–8 short and stout spine-like cornuti. Female genitalia. Lamella postvaginalis composed of three lobes, central lobe rounded anteriorly, tapered to posterior end; lateral lobes oval; lamella antevaginalis with dentate margin. Ductus bursae barely differentiated from corpus bursae, with a short antrum posteriorly. Corpus bursae with a signum anteriorly; signum weakly sclerotized, with two teeth centrally.

Diagnosis. This species is difficult to distinguish from A. kishidai (figs 3, 4, 7, 8) on external characters. However, the male genital structures differ substantially: the basal projection of the costa is less distinct than that of A. kishidai ; a short digitiform process is formed on the inner surface of the apex of sacculus, while in A. kishidai , a cluster of short spines are present in the same area; the aedeagus is distinctive in having a triangular process posteriorly, which is absent in A. kishidai . In the female genitalia, the posterior half of the central lobe of the lamella postvaginalis is triangular, while in A. kishidai , it is rounded; the lamella antevaginalis is narrower.

Type material. Holotype, ♂, CHINA: Guangxi ( IZCAS): Jinxiu, Shengtangshan , 1900 m, 17.V.1999, coll. Yuan Decheng. Paratypes: Guangxi ( IZCAS): 1♂, Jinxiu, Shengtangshan, 1900 m, 17. V.1999, coll. Zhang Yanzhou; 1♀, Jinxiu, Yinshanzhan , 1100 m, 10. V.1999, coll. Li Wenzhu.

Distribution. China (Guangxi).

Etymology. The specific name is from the Latin prefix trigono - and the word processus, which means triangular process, in reference to the process of the aedeagus.

Remarks. After examining the holotype of A. kishidai (S. China, Guangdong, Shaoguan, Nanling National Nature Reserve, 1100 m, 18–22.VI.2003, K.Yazaki leg.) in SCAU and specimens in IZCAS of A. kishidai (2♂ 1♀, Zhejiang, Qingyuan, Fengyangshan, Datianping, 6–10.VIII. 2003, 1290 m, coll. Han Hongxiang; 1♀, Hunan, Daoxian, Tiejiangchang, 18.VIII.1982; 1♂ 1♀, Fujian, Sanming, 16.VII.1981, 18.VI.1981; 1♀, Guangdong, Ruyuan, Nanling, Baohuzhan, 1020 m, 16–20.VII.2008, coll. Chen Fuqiang; 1♂, Guangxi, Longsheng, Hongtan, 900 m, 11.VI.1963, coll. Wang Chunguang), we confirmed that A. trigonoprocessa is different from A. kishidai in the male and female genitalia.

Figures

FIGURES 1–8. 1–4. Adults of Arbomia. 1, A. trigonoprocessa sp. nov., male, holotype; 2, ditto, underside; 3, A. kishidai, male, holotype; 4, ditto, underside; 5–8. Genitalia of Arbomia. 5, A. trigonoprocessa sp. nov., male, holotype; 6, ditto, female, paratype; 7, A. kishidai, male; 8, ditto, female.