Review of the genus Isodemis Diakonoff (Lepidoptera, Tortricidae) from China, with description of three new species

Abstract The genus Isodemis Diakonoff, 1952 in China is reviewed, with seven species recognized. Three new species are described: Isodemis quadrata sp. n., Isodemis guangxiensis sp. n. and Isodemis hainanensis sp. n. The female of Isodemis stenotera Diakonoff, 1983 is described for the first time. Variation within Isodemis illiberalis (Meyrick, 1918) and Isodemis stenotera is briefly discussed. Images of the adults and genitalia are provided, along with a key to the described species.


Introduction
Th e genus Isodemis was erected by Diakonoff (1952) for the type species Batodes serpentinana Walker, 1863. It belongs to the tribe Archipini in the subfamily Tortricinae. Diakonoff (1976Diakonoff ( , 1983 transferred Tortrix illiberalis Meyrick, 1918 to Isodemis and described I. stenotera from Sumatra. Razowski (2000Razowski ( , 2009aRazowski ( , 2009b described Razowski, 2000 from Chinese Taiwan, and I. brevicera Razowski, 2009, I. longicera Razowski, 2009 and I. ngoclinha Razowski, 2009 from Vietnam. Currently, Isodemis consists of seven species, mainly distributed in Southeast Asia. Prior to the present study, four species were recorded in China: I. serpentinana (Walker, 1863), I. illiberalis (Meyrick, 1918), I. stenotera Diakonoff , 1983 andI. proxima Razowski, 2000. Th e aim of the present paper is to review the genus Isodemis in China and to describe three new species. A key is provided on a worldwide basis based on the forewing patterns and the male genitalia except I. ngoclinha Razowski, 2009 whose male remains unknown. A map is provided to show the distribution of Isodemis species in China (Map 1).

Material and methods
Examined specimens were collected by light traps. Terminology follows Diakonoff (1948) and Razowski (2009a, b) in descriptions of forewing pattern and genitalia. Genitalia dissection and slide mounting methods follow Li (2002). Th e examined specimens, including the types of the new species, are deposited in the Insect Collection, College of Life Sciences, Nankai University, Tianjin, China.
Diagnosis . Isodemis is characterized by the labial palpus obliquely uprising almost as high as upper edge of eye; the forewing dominantly yellowish brown or ochreous brown; the median fascia interrupted or indistinct near costal margin; male genitalia with gnathos hooked, valva with a C-shaped plica, with numerous fi ne wrinkles between plica and costa, and the sacculus with terminal process; female genitalia with the ductus bursae usually with cestum, and the single dentate signum with a conspicuous globular process placed posteriorly in the corpus bursae. Distribution. China, Vietnam, Th ailand, Indonesia, Nepal, India and Sri Lanka. Discussio n. Most species of this genus show a stong sexual dimorphism, which makes species identifi cation diffi cult. Of the seven previously described species , I. longicera Razowski, 2009 andI. brevicera Razowski, 2009 were described from the males, while I. ngoclinha Razowski, 2009 was described from females. Currently, no additional knowledge has been added to these three species. Th erefore, we have excluded I. ngoclinha from the key based on forewing patterns and male genitalia.  Fig. 1) with wingspan 16.0-19.5 mm. Th is species is characterized by the male genitalia with the uncus broadening from basal 1/3 to blunt apex, and the phallus having eight to twenty-three deciduous cornuti and a single non-deciduous cornutus ; in the female genitalia by the sterigma deeply V-shaped, the ductus bursae about 1.5 times the corpus bursae, and the globular process almost 1/2 length of the signum (Diakonoff 1941: 40, fi g. 5). It can be easily distinguished from its congeners by the median fascia extending from below distal half of the costal fold to the dorsum and the subapical blotch reaching the tornus.

Key to the known species of Isodemis
Distribution. China (Guangdong, Guangxi, Yunnan), Vietnam, Th ailand, India, Nepal. Variation. Th e uncus broadens from basal 1/3 to apex and the p hallus has sixteen to twenty-three deciduous cornuti and a single non-dec iduous cornutus in the specimens collected in Guangxi (Fig. 11); while the uncus is parallel sided and the phallus bears eight deciduous cornuti and a single non-deciduous cornutus in the specimens collected in Yunnan (Fig. 12).    Diagnosis. Th is species is very similar to the type species I. serpentinana both in appearance and in the genitalia, but can be distinguished by the male genitalia having two nearly straight cornuti that are equal in length, and the female genitalia having the ductus bursae about the same length as the corpus bursae and broadening slightly from the inception of the ductus seminalis to the corpus bursae. In I. serpentinana, the male genitalia have a phallus bearing two cornuti tha t are unequal in length with the longer one undulate, and the female geni talia have a ductus bursae about 1.5 times the length of the corpus bursae and slightly broader from middle of the ductus seminalis to corpus bursae (Diakonoff 1948: 511, fi g. 37).

Isodemis stenotera Diakonoff , 1983
Description. Adult: Male (Figs 2-3) wingspan 17.5-22.0 mm. Female (Fig. 4) wingspan 19.0-27.0 mm. Head, antenna and labial palpus yellow, scattered with ochreous. Th orax and tegula ochreous brown tinged with yellow. Forewing broad, nearly rectangular, apex slightly protruding anteriorly; ground color yellow, with scattered pale ochr eous scales medially, densely covered with ochreous brown scales along dorsal area; m arkings ochreous brown with sparse brownish black scales: costal margin with two dots near base, with a triangular spot at basal 1/5; median fascia interrupted or indistinct medially, extending to distal 1/3 of dorsum, then along tornus obliquely reaching anteriorly to middle of termen; faint pale ochreous yellow stripe from below costal portion of median fascia to termen below apex, gradually narrowing; subapical blotch from middle of costal margin to before apex, narrowly stripe-shaped, with brownish black and yellow dots along costal margin; cilia ochreous mixed with brownish black, yellow at apex. Hindwing pale grayish brown, distally with a large yellow patch tinged with sparse pale ochreo us brown scales; cilia pale grayish brown. Legs pale yellow, mixed with brownish black on ventral side of foreleg; outer side of mid-and hindlegs yellow, tinged with brownish black. Abdomen grayish brown.
Variation. In some male individuals, the median fascia has a small brownish yellow spot placed near the posterior 1/4 of termen, connected with the yellow stripe above it (Fig. 3); the vinculum has a tiny spine at middle on the anterior margin in the male genitalia.
Notes. Th e female of this species is described for the fi rst time.  5) with wingspan 16.0-21.0 mm. Th is species is very similar to I. stenotera both in appearance and in the genitalia, but can be distinguished by the forewing dominantly dark ochreous brown; the uncus narrowed basally and the phallus with single cornutus in male genitalia (Fig. 14); and the ductus bursae about 1.5 times length of the corpus bursae in female genitalia (Razowski, 2000: 325, fi g. 14). In I. stenotera, the forewing is mainly ochreous brown; the uncus is broadened basally and the phallus bears two cornuti; and the ductus bursae ia about the same length as the corpus bursae.

Isodemis serpentinana (Walker, 1863)
Batodes Distribution. China (Hainan, Yunnan, Taiwan); India, Indonesia (Borneo, Java, Sumatra), New Guinea, Philippine, Sri Lanka, Tailand. Notes. Based on the description of I. serpentinana and the illustration of its male genitalia provided by Diakonoff (1941), this species is distinguished by the phallus bearing two unequal cornuti with the longer one undulate in the male genitalia. When Diakonoff (1983) described I. stenotera, he pointed out that I. stenotera was very similar to I. serpenti nana superfi cially, but could be separated by the male genitalia having two cornuti equal in length. By checking the holotype deposited in the Natural History Museum, London, we also found that the subapical blotch in I. s erpentinana is subtriangular, while it is narrowly semioval in I. stenotera. More diff erences of the two species are stated under I. stenotera. Diagnosis. Th e male is simila r to I. illiberalis superfi cially, but can be separated by the median fascia extending from the costal margin to the do rsum, the subapical blotch reaching across 1/3 width of wing and the quadrat e uncus. In I. illiberalis, the median fascia extends from the lower edge of costal fold to the dorsum, the subapical blotch reaches the tornus, and the uncus broadens from the basal 1/3 to the apex. Th e female genital ia are close to those of I. stenotera, but can be distinguished by the ductus bursae being longer than the corpus bursae and the signum without tiny spines on its ventral surface; in I. stenotera, the ductus bursae is about the same length as the corpus bursae and the signum consists of tiny spines on its ventral surface. In addition, the female can be easily separated from I. stenotera by the ground color being yellowish brown mixed with ochreous, the median fascia extending from the costal margin to distal 1/3 of the dorsum, and the subapical blotch nearly inverted triangular; in I. stenotera, the ground color is yellow with scattered pale ochreous scales, the median fascia reaches the middle of termen and is interrupted or indistinct medially, and the subapical blotch is narrowly stripe-shaped.

Isodemis quadrata
Description. Adult: Male (Fig. 6) wingspan 19.5-20.0 mm. Head, antenna and labial palpus yellowish brown, with scattered ochreous brown. Th orax and tegula ochreous brown mixed with yellowish brown. Forewing yellowish brown with sparse ochreous scales; costal fold tinged with brownish black, about 3/5 length of costal margin; markings brownish black mottled with ochreous: median fascia extending from costal marg in to distal 1/3 of dorsum, s lightly interrupted near costal fold, with a large rounded gray patch present on its outer side posteriorly; short stripe from basal 1/3 of dorsum extending anteriorly and joining inner side of median fascia at anterior 1/3, forming an irregular semicircular pattern above dorsum, leavin g a rounded subtriangular patch of groundcolour at middle of dorsum; subapical blotch inverted triangular, extending from distal 1/3 of costal margin to before apex, reaching across 1/3 width of wing; cilia yellowish brown. Hindwing dark gray, distally with a p ale grayish brown patch tinged with yellowish brown; cilia dark gray. Legs dark yellow, tinged wi th brownish black on ventral side of foreleg and on outer side of mid-and hindlegs. Abdomen grayish brown. Female (Fig. 7) wingspan 21.0-22.5 mm. Head and labial palpus dark grayish brown. Antenna brownish black tinged with yellowish brown. Forewing broader than in male, nearly rectangular, apex slightly protruding anteriorly; costal margin tinged with brownish black; posterior 4/5 of median fascia ochreous brown with sparse brownish black scales; lower edge of subapical blotch slightly rounded ; with small diff used patch placed near middle of termen. Hindwi ng gray, anterodistally with a yellowish brown patch mottled with brownish black.
Male genitalia (Fig. 15). Tegumen developed. Unc us nearly quadrate, straight on posterior margin. Gnathos arm slender and long; terminal plate nearly triangular, about 1/3 length of arm. Valva with length about 1.5 times width, rounded t erminally; transtilla sp ine-shaped, disconnected medially. Sacculus weakly sclerotized; terminal process nearly thumblike, reaching plica. Vinculum somewhat concave at mid dle on anterior margin, with two small spines near middle of anterior margin. Juxta approximately oval, slightly concave at middle ant eriorly. Phallus slightly l onger than length of valva, straight, dilated basally, with ten deciduous cornuti and a single non-deciduous cornutu s that is about 1/3 length of phallus.
Distribution. China (Tibet). Etymology. Th e specifi c name is from the Latin quadratus (= square), referring to the rectangular uncus in the m ale genitalia. Diagnosis. Th is species is similar to I. illiberalis both in appearance and in male genitalia, but can be separated by the median fascia extending from the costal margin to the dorsum, the subapical blotch reaching across 1/3 width of wing and the phallus having eight deciduous cornuti and two non -deciduous cornuti. In I. illiberalis, the median fascia extends from below the costal fold to the dorsum, the subapical blotch reaches the tornus and the phallus has eight to twenty-three deciduous cornuti and a single non-deciduous cornutus. Isodemis guangxiensis is superfi cially also similar to I. quadrata, the diff erences between them are as follows: in I. guangxiensis, the uncus broadens from the basal 1/4 to the apex and the phallus bears eight deciduous cornuti and two non-deciduous cornuti, whereas in I. quadrata, the uncus is quadrate and the phallus has ten deciduous cornuti and a single non-deciduous cornutus.

Isodemis guangxiensis
Description. Adult: Male (Fig. 8) wingspan 18.0-18.5 mm. Head yellowish brown. Antenna and labial palpus ochreous brown, with scattered yellowish brown scales. Th orax and tegula dark grayish brown, sparsely mixed with yellowish brown. Forewing yellowish brown tinged with ochreous scales; costal fold densely suff used with brownish black scales, about 3/5 length of costal margin; markings brownish black mottled with ochreous: media n fascia extending from co stal margin to distal 2/5 of dorsum, interrupted near costal margin, with nearly oval gray patch present on its outer side posteriorly; short stripe from basal 1/4 of dorsum extending anteriorly and touching inner side of median fascia at anterior 1/3, forming an irregularly semicircular pattern above dorsum, leaving a rounded subtriangular patch of groundcolour near middle of dorsum; subapica l blotch inverted triangular, from distal 1/3 of costal margin to before apex, reaching across 1/3 width of wing; with sma ll diff usion near middle of termen; cilia yellowish brown mixed with brownish black. Hindwing and cilia grayish brown. Legs dark yellow, mottled brownish black on ventral side of foreleg and on outer side of mid-and hindlegs. Abdomen grayish brown.
Male genitalia (Fig. 16). Uncus nearly rectangular in basal 1/4, then broadene d slightly to rounded apex, densely setose in distal half. Gnathos arm slender and long; terminal plate triangular, about 2/3 length of arm. Valva slightly widened distally, length about 2 times of width, rounded terminally; transtilla irregularly round, with pointed apical process. Sacculus weakly sclerotized, protruding ventrally at middle; terminal process nearly triangular, rounded at apex, reaching plica. Vinculum somewhat concave at middle on anterior margin. Juxta large and broad, straight on anterior margin; posterior margin concave and arched, protruding posterolaterally. Phallus slightly shorter than length of valva, slightly curved and dilated in basal 2/5, with eight deciduous cornuti and two non -deciduous unequal cornuti that are about 1/3 length of phallus.

Distribution. China (Guangxi).
Etymology. Th e name is derived from the type locality. Diagnosis. Th is species is superfi cially very similar to I. longicera and I. brevicera, but it can be separated by the uncus being slightly narrowed in the distal 2/5 and rounded apically, the spine-shaped terminal proc ess of the sacculus not reaching plica and the phallus bearing eight cornuti. In I. longicera, the uncus is slightly concave at middle on posterior margin, the terminal process of the sacculus reaches the plica and the phallus bears twelve cornuti; in I. brevicera, the uncus broadens from base to apex, the termi-nal process of the sacculus is nearly triangular, and the phallus has ten cornuti. Female genitalia rese mble those of I. ngoclinha, but can be distinguished by the anterior portion of the papilla analis not being infl ated and the sterigma extending posteriorly uniformly in width to both sides; whereas in I. ngoclinha, the basal 2/3 of papilla analis is infl ated, and the sterigma widens from the inception of ductus bursae to the lateral side.
Description. Adult: Male (Fig. 9) wingspan 17.5 mm. Head, antenna and labial palpus grayish brown, mixed with brownish black scales. Th orax and tegula brownish black, with sparse grayish brown scales. Forewing dark yellowish brown, tinged with ochreous scales in distal half; costal fold narrow, about 1/2 length of costal margin, brownish black, with short black stripes along costal margin; markings brownish black mottled ochreous: median fascia interrupted near cost al margin, reaching above tornus, then extending obliquely anteriorly to lower corner of cell; longitudinal broad median stripe from apical margin of median fascia to end of cell, forming an annular pattern with indentation; subapical blotch from distal 2/5 of costal margin to apex, reaching across 1/4 width of wing; pale brownish black terminal lines between veins; dorsal area densely suff used with grayish brown scales, forming a broad band along dorsum; cilia grayish brown mixed with brownish black. Hindwing and cilia grayish brown. Legs dark yellowish brown, mottled brownish black on ventral side of foreleg and on outer side of mid-and hindlegs. Abdomen dark grayish brown.
Female (Fig. 10) wingspan 22.0 mm. As in male except with small, brownish black basal fascia near base; costal margin more arched basally than in male; subapical blotch from middle of costal margin to apex, narrow, reaching across 1/5 width of wing; stripe along anal vein to beyond mid-length of wing.
Distribution. China (Hainan). Etymology. Th e name is from the type locality.