﻿Four new species of Ditrigona Moore (Lepidoptera, Drepanidae) in China and an annotated catalogue

﻿Abstract The Chinese species of the genus Ditrigona Moore, 1888 are reviewed and an annotated catalogue is provided. Four new species are described from China: Ditrigonasinespina Jiang & Han, sp. nov., Ditrigonaparva Jiang & Han, sp. nov., Ditrigonaconcava Guo & Han, sp. nov., and Ditrigonafusca Guo & Han, sp. nov.Derocacrystalla Chu & Wang, 1987 and Auzatellapentesticha Chu & Wang, 1987 are newly combined into, respectively, the derocina and quinaria species groups of Ditrigona. Ditrigonadiana Wilkinson is newly recorded in China. This results in 43 species of Ditrigona for the fauna of China. Illustrations of habitus and genitalia of the new species and most known species are presented.


Introduction
The genus Ditrigona was originally established by Moore (1888) on the basis of Urapteryx triangularia Moore, 1868 from India. Later, Warren (1922) described Ditrigona regularis Warren from Assam, and Bryk (1943) described Ditrigona regularis differentiata Bryk from Burma. After a long silence in research into Ditrigona,  provided the most comprehensive revision of the genus. He established three new generic synonyms of the genus, and transferred most of the species involved into Ditrigona; altogether he recorded 40 species and 12 subspecies for the genus, including   placed three species in the derocina species group: Ditrigona derocina (Bryk), Ditrigona diana Wilkinson, and Ditrigona pruinosa (Moore). The two former species have been recorded in China, and a further species, Deroca crystalla Chu & Wang, 1987 is newly placed in this species group in this work. Species of the derocina species group are characterized by unipectinate antennae and semi-transparent wings. In the male genitalia, the derocina species group is unusual in Ditrigona in having sclerotization of the vinculum, and a quite long and narrow aedeagus. The eighth sternite is distinguished by large and curved octavals, and the tergite protrudes strongly. The female genitalia are characterized by having a very long ductus bursae, an ostial plate, an accessory sac and a long and narrow signum.    recorded 11 species in the quinaria species group: Ditrigona spilota Wilkinson, Ditrigona inconspicua (Leech), Ditrigona furvicosta (Hampson), Ditrigona jardanaria (Oberthür), Ditrigona media Wilkinson, Ditrigona innotata (Hampson), Ditrigona sericea (Leech), Ditrigona quinaria (Moore), Ditrigona obliquilinea (Hampson), Ditrigona idaeoides (Hampson), and Ditrigona spatulata Wilkinson. The former 10 species are recorded in China, and Auzatella pentesticha Chu & Wang is newly combined to Ditrigona in this work.
Species of the quinaria species group share bipectinate or serrate antennae with some species of the triangularia and mytylata species groups. In the male genitalia, the uncus is usually single, but sometimes bifurcate or notched. The single uncus resembles that of species of the derocina species group, but the group can be differentiated by the lack of sclerotization on the vinculum, and the large and broad saccus. The small and setose valva lacking a posterior projection also differs from those in the triangularia and mytylata species groups. The aedeagus is often characterized by the presence of a minute to large apical projection (not present in D. spilota and D. obliquilinea, and the situation unknown in D. innotata and D. idaeoides). The eighth sternite is modified with short octavals, and the tergite is often shallowly to moderately concave, occasionally straight or protruding with tiny lateral projections. The female genitalia lack an ostial plate; the ductus bursae is short and broad, and the corpus bursae usually has an accessory sac and a long and thin signum. Wilkinson, 1968 Figs 4, 51, 85, 119, 155 Ditrigona spilota Wilkinson, 1968: 423 1968) of D. spilota, the socii of the paratype examined are much broader and blunter, while the aedeagus and 8 th segment have no distinct differences. Further study is needed to investigate whether this is intraspecific variation, or more than one species is present in the large type series.

Remarks.
As stated under the above species, this species now only includes the female holotype. The validity of the species needs further study, for example, by obtaining a DNA barcode from the holotype.

Ditrigona quinaria (Moore, 1867)
Drepanodes quinaria Moore, 1867: 618. Neotype ♂, India: Darjiling (NHMUK). Ditrigona quinaria: Wilkinson, 1968: 438. Note. At present, D. quinaria comprises five subspecies; four are recorded from China, the exception being D. quinaria nivea (Hampson), which is distributed in India. ( (Hampson) lack the tail process. The first nine species are recorded in China, and three new species (D. sinespina, D. parva, D. concava) with the tail process are described in this work. The species with a tail process on the hind wing have quite distinct wing patterns: the hind wing has the postmedial and submarginal lines approaching each other near the anal angle, and bears a small black patch at the upper angle of the tail. The species lacking a tail process resemble some species of the mytylata species group, in that they have transverse lines which often resemble a narrow band. In the male genitalia, the valva is characterized by having a small flap-like extension. The species with a tail process can also be distinguished by the large rounded socii and the stout aedeagus bearing a brush-like cornutus. In the species lacking a tail process, the aedeagus is narrow, straight or bent, and the cornutus is a simple process or absent. The eighth sternite is small, shallowly concave or protruding in species with a tail process, and the eighth tergite almost unmodified. Both eighth tergite and sternite often possess octavals in the species lacking a tail process. In the female genitalia, the ostium bursae is usually large, and the ductus bursae is often indiscernible, but wide and obvious in D. typhodes. The corpus bursae bears a small accessory sac in species with a tail process. (modified from  16 DAN barcoding sequences were obtained for D. regularis, D. triangularia, D. tenuiata, D. concava sp. nov., D. parva sp. nov., and D. sinespina sp. nov., and the six species are clearly separated from each other in the COI barcode fragment ( fig. 178). The genetic distance between these species is 8.92% (min. 7.16%, max. 12.32%). Thorax. Dorsal and ventral sides of thorax white. Tegula white. Hind tibia with two pairs of spurs in both sexes. Forewing length: ♂♀16 mm. Both fore-and hind wings white, transverse lines grey. Forewing with costa pale brown, distal half deeper. Subbasal and antemedial lines slightly bent inwards at middle and costa, the former narrower; postmedial line broad, almost straight; submarginal line double, the inner one slightly wavy and the outer one deeply wavy. Hind wing with antemedial line straight, merging into the elongate grey area along anal margin; postmedial line broader, almost straight, closing to submarginal line near anal angle, forming large pointed teeth on CuA 2 and anal fold; submarginal line double, with the inner one nearly straight and only wavy near anal angle, the outer one wavy, the two lines gradually approximating towards anal margin. Anal margin less extended, possessing a quite short tail process, longer in female, with a small black patch. Fringes pale brown. Forewing underside with costa deep brown in basal half.

Ditrigona triangularia
Abdomen. Dorsal and ventral sides of abdomen white. Eighth tergite large, nearly quadrate, with posterior margin shallowly concave; eighth sternite concave at middle, forming two small lateral blunt processes.
Male genitalia. Uncus bifurcate over its whole length, both halves short and very narrow. Socii large, rounded. Valva small, ventral margin smoothly curved, distal and posterior margins straight, forming a blunt angle; posterior protrusion rounded. Saccus blunt and rounded. Juxta indistinctly shaped. Aedeagus very stout, terminal part narrower; cornutus a large oval spinose patch.
Diagnosis. On the wing pattern, D. sinespina is close to D. tenuiata, but it can be differentiated by the larger distance between the two submarginal lines on the forewing, and the smaller tail process. Compared to D. triangularia and D. uniuncusa, the anal margin of D. sinespina is less extended, and the tail process is distinctly shorter than in those two species. Compared to D. parva sp. nov. and D. concava sp. nov., D. sinespina is larger (with forewing length 16 mm), and the tail process on the hind wing is less developed.
In the male genitalia, the slender uncus is similar to that of D. tenuiata and D. concava, but it is longer than in D. tenuiata and shorter than in D. concava. The straight distal margin of the valva is also different from these two species. The shape of the aedeagus, which is broad and blunt posteriorly, also can be distinguished from these two species. The eighth tergite of the male is similar to that of D. concava, but the eighth sternite is different: in D. sinespina it is narrowly and deeply concave, forming two blunt protrusions, while in D. concava it is widely and shallowly concave, forming two small lateral processes. The female genitalia of D. sinespina are also similar to those of D. tenuiata, but can be differentiated by the lack of a signum. Distribution. China (Yunnan). Etymology. The species is named from the Latin words sine and spina, which refers to the lack of a signum in the female genitalia.
Diagnosis. The wing pattern is very close to that of D. uniuncusa. The antemedial line on the hind wing is straight in D. parva, but slightly convex in D. uniuncusa. The width between the two submarginal lines is larger than in D. uniuncusa, especially in the female. In the male genitalia, D. parva shares a stout uncus with D. uniuncusa and D. regularis, but the terminal half of the socii are quite different: scobinate and semicircular in D. parva, scobinate and tapering in D. uniuncusa, and spinose in D. regularis. The female genitalia are also different: the sclerotized area on the corpus bursae is rounded, less sclerotized and smaller than that in D. uniuncusa, which has a large oval well sclerotized area; the signum is shorter than in D. uniuncusa.
Type Description. Characters of head and thorax in male same as in D. sinespina. Forewing length 16 mm in male. Fore-and hind wings white, transverse lines grey. Forewing with costa pale brown. Subbasal line slightly bent inwards at middle and costa; antemedial line straight and only bent inwards near costa; postmedial line broad, almost straight; submarginal line double, the inner one slightly wavy and the outer one deeply wavy. Hind wing with antemedial line slightly convex at middle, bent outwards and merging into the elongate grey area along the anal margin; postmedial line broader, almost straight, slanting outwards and closing to meet submarginal line near anal angle, forming large pointed teeth on CuA 2 and anal fold; submarginal line double, with the inner one nearly straight and only wavy near anal angle, the outer one wavy, the two lines gradually approximating towards anal margin. Anal margin less extended, with a quite short tail process, longer in the female, with a small black patch. Fringes pale brown. Forewing underside with costa deep brown in basal half.
Female genitalia. Unknown. Diagnosis. The most distinctive character of D. concava lies in the male eighth sternite, which is different from all other congeners by the wide and shallow concavity, bearing two small lateral processes. The male genitalia are similar to those of D. tenuiata and D. sinespina, and can be differentiated by the following differences: the uncus is longer than in those two species; the distal and posterior margins of the valva are shallowly concave in D. concava, but the two margins are straight in D. sinespina.

Ditrigona sciara Wilkinson, 1968
Ditrigona sciara Wilkinson, 1968: 458 This species group is characterized by usually having lamellate antennae, and the valva of the male genitalia usually possessing a long posterior extension. Other characters are summarized as follows: the forewing is sometimes weakly falcate; the streaks vary considerably, with transverse lines linear, band-like or absent; the uncus is bifurcate, and the socii are very large; the aedeagus is usually arcuate; both eighth sternite and tergite are modified, the former with short octavals, and the latter concave with small or large protrusions; in the female genitalia, the ostial pocket is characteristic, and the corpus bursae lacks an accessory sac. (modified from
Male genitalia. Uncus bifurcate over whole length, the arms narrow and slender. Socii large, tongue-like, of even width, with tips blunt and scobinate. Valva nearly triangular, with tip blunt, ventral margin decorated with tiny spines; basal posterior process bent, tip expanded, with a small accompanying bursa. Juxta rounded, with posterior margin protruding, mound-like. Saccus narrow. Aedeagus slender, almost even in width, tip blunt.
Diagnosis. The wing pattern is distinctive in lacking transverse lines on both foreand hind wings. The male genitalia are very close to those of D. candida, D. chionea and D. margarita in the mytylata species group, in that they share the slender bifid uncus and tongue-like socii. D. fusca and D. chionea can be differentiated from those two species by the broader valva, on the base of which a sclerotized ridge is present. The difference between D. fusca and D. chionea in the male genitalia lies in the shape of the juxta, which is widely protruding posteriorly in D. fusca, but only with a tiny process at middle in D. chionea. The aedeagus is also different, straight and almost even in width in D. fusca, but tapering and twisted in D. chionea. The female genitalia of D. fusca and D. chionea are almost identical.