Studies on external genitalia of seven Indian species of the genus Spilarctia Butler (Lepidoptera: Arctiidae: Arctiinae) alongwith the description of a new species

Genus Spilarctia was established in 1875 by Butler on the type species Phalaena lutea Hufnagel, 1766, from Germany. This genus was synonymised under Spilosoma Stephens, 1828, by Hampson in 1894. However, in 1901, Hampson described the genus Diacrisia Hübner, 1819, in a broader concept and synonymised 31 genera under it which also included both the genera i.e., Spilarctia Butler and Spilosoma Stephens. Seitz (1910) introduced the division of the family Arctiidae into eight subfamilies and transferred the genus Spilarctia Butler under Spilosominae. Later, Daniel (1943) followed this division in spite of the fact that Strand (1919) treated Spilosominae as a synonym of Arctiinae. Arora & Chaudhary (1982) and Arora (1983) followed the classification given by Seitz (1910). Holloway (1988) used Spilosoma Curtis (=Spilosomoa Stephens) as a valid generic name. Koda (1988) brought out an important publication on the generic classification of subfamily Arctiinae of the Palearctic and Oriental regions based on the male and female genitalia. He re-characterized the genus Spilosoma Curtis and Spilarctia Butler and provided suitable status to both these genera in this publication. Kirti & Singh (1994) studied the genitalic structures of four Indian species i.e. Spilarctia multiguttata Walker, S. casignata Kollar, S. obliqua Walker and S. comma Walker. In the present study a large sample of 43 representatives were collected from different localities of Western Ghats of India. On close examination of morphological characters, seven species were separated. Out of these, six species were identified from the relevant literature and by comparison with the collections preserved in different national museums viz., Indian Agricultural


INTRODUCTION
Genus Spilarctia was established in 1875 by Butler on the type species Phalaena lutea Hufnagel, 1766, from Germany.This genus was synonymised under Spilosoma Stephens, 1828, by Hampson in 1894. However, in 1901, Hampson described the genus Diacrisia Hübner, 1819, in a broader concept and synonymised 31 genera under it which also included both the genera i.e., Spilarctia Butler and Spilosoma Stephens. Seitz (1910) introduced the division of the family Arctiidae into eight subfamilies and transferred the genus Spilarctia Butler under Spilosominae.Later, Daniel (1943) followed this division in spite of the fact that Strand (1919) treated Spilosominae as a synonym of Arctiinae.Arora & Chaudhary (1982) and Arora (1983) followed the classification given by Seitz (1910).Holloway (1988) used Spilosoma Curtis (=Spilosomoa Stephens) as a valid generic name.Koda (1988) brought out an important publication on the generic classification of subfamily Arctiinae of the Palearctic and Oriental regions based on the male and female genitalia.He re-characterized the genus Spilosoma Curtis and Spilarctia Butler and provided suitable status to both these genera in this publication.Kirti & Singh (1994) studied the genitalic structures of four Indian species i.e.Spilarctia multiguttata Walker, S. casignata Kollar, S. obliqua Walker and S. comma Walker.In the present study a large sample of 43 representatives were collected from different localities of Western Ghats of India.On close examination of morphological characters, seven species were separated.Out of these, six species were identified from the relevant literature and by comparison with the collections preserved in different national museums viz., Indian Agricultural Research Institute (IARI), New Delhi, Forest Research Institute (FRI), Dehradun and Natural History Museum (NHM), London.One species could not be identified from these sources.This species is described here as new to science.

MATERIALS AND METHODS
The material for the present study i.e., the adult moths of family Arctiidae were collected exclusively from fluorescent lights during night hours from different localities in the Western Ghats of India.The collected moths were killed with ethyl acetate vapors in the killing bottle.The freshly killed specimens were pinned and stretched on adjustable wooden stretching boxes.The pinned specimens were dried for 2-3 days in the improvised drying chambers.The properly dried specimens were then preserved in air tight wooden boxes, containing naphthalene balls as fumigants.
To study wing venation permanent slides of fore and hind wings were made.For this, the methodology given by Common (1970) and advocated by Zimmerman (1978) was followed.For the study of external male and female genitalia, the entire abdomen of the preserved moths was removed, as cutting only the last few segments often damages constituent parts of male and female genitalia (Robinson 1976).The detached abdomen was put in 10% KOH for 12-14 hr. in order to soften chitin and dissolve muscles and other soft parts.The KOH treated material was washed in distilled water and residual traces of KOH were later removed by putting it in 1% glacial acetic acid.The abdomen was dissected in 50% alcohol for taking out the genitalia and adhering unwanted material was cleared in the subsequent grades.After proper dehydration, the material was cleared in clove oil and preserved in a ratio of 3:1 alcohol and glycerol.The diagrams were drawn with the help of a graph eye piece fitted in a zoom binocular.BUTLER Butler,1875, Cistula Entomolgica, 2: 39.Type species: Phalaena lutea Hufnagel, 1766, Germany: Berlin; type deposited in Natural History Museum (NHM), London, subsequent designation by Kirby 1877 in Rye Zoo.Rec. 12 : 431.
Diagnosis: Labial palpi porrect or porrectly rosteriform.Antennae bipectinate in males, ciliated in females.Forewing with vein R 1 arising from cell; R 2 , R 3 , R 4 and R 5 from a common stalk; M 1 from upper angle; M 2 from or slightly beyond lower angle of cell.Hindwing with vein Sc+R 1 originating towards base of cell; Rs and M 1 from upper angle; M 2 from lower angle or towards middle of discocellulars.Hind tibia with two pairs of spurs.Male genitalia with uncus moderately long, broad at base and gradually narrowing towards tip; acrotergite well developed; fenestrula absent; saccus present; valvae simple with costa narrow and linear, sometimes produced at proximal end; sacculus present, valvula and cucullus not clearly differentiated; juxta trapejoid; aedeagus moderately long and broad; vesica membranous with irroration of small spines; ductus ejaculatorius entering subapically.
Female genitalia with corpus bursae membranous, signum present or may be absent; ductus seminalis entering ductus bursae.
(Figure 1) Remarks: Only three female specimens of mona Swinhoe were collected in 1885 by Swinhoe from Bombay and Mahabaleshwar.Till date, no male representative of this species was studied and associated for mona Swinhoe except Kaleka (2005).It seems that this Indian worker has wrongly identified the above said species collected from northeastern India, because, in the female genitalia of mona Swinhoe three signa are present whereas, Kaleka (2005) has mentioned that the signum is missing in this species.Kaleka ( 2005) not only shifted it under genus Thanatarctia Butler on the basis of external male and female genitalic structures, but also provided wrong information in his publication that the species mona Swinhoe was studied by Koda (1988) under the genus Spilarctia Butler.
In the present study only two female representatives were collected from Mahabaleshwar and Matheran, which clearly point out that geographically the species is very much restricted.The detailed study of morphological and female genitalic structures of species under reference confirms that it is better to place it under the genus Spilarctia Butler rather than under Thanatarctia Butler or Diacria Hübner.Hence, the proper status of mona Swinhoe has been provided in the present work.(Figure 4) Head with frons and vertex ochreous.Antennae bipectinate in males; scape and pedicel ochreous; shaft and branches dark brown.Eyes fuscus green with black spots or patches.Labial palpi porrect; laiden with crimson scales; third segment brown.
Thorax, collar and tegula ochreous, thorax with a small black streak.Forewing with ground colour ochreous, slightly irrorated with crimson scales; costa suffused with crimson scales; a basal black spot; antemedial spot on vein 1A; a black speck at end of cell; an oblique series of postmedial spots on both sides of veins, not reaching costa; traces of submarginal series of black spots; underside with irroration of crimson scales; a black spot at end of cell; fringe ochreous; vein R 1 from cell; R 2 , R 3 , R 4 and R 5 from a common stalk; M 1 from upper angle; M 2 slightly beyond angle; M 3 from angle of cell; Cu 1 near angle of cell; Cu 2 from middle of cell.Hindwing with ground colour ochreous; inner margin suffused with crimson scales; a black spot at end of cell; more or less complete series of submarginal spots; underside same; fringe ochreous; vein Sc+R 1 originating before middle of cell; Rs and M 1 from upper angle; M 2 towards middle of discocellulars; M 3 and Cu 1 from lower angle; Cu 2 from middle of cell.Legs black brown; coxae and trochanter suffused with crimson scales; hind tibia with two pair of spurs.
Remarks: Morphologically the species under reference is closely allied to obliqua Walker.But the perusal of external male genitalic structures reveals that it is a different species.Its distinct male genitalic characters like shape of vinculum, juxta and valvae justify its status.
Etymology: The name of the species belong to the district of its type locality i.e., Coorg (Kodagu).
Remarks: The species has been discussed in considerable detail by many previous authors like Koda (1988) and Kirti & Singh (1994).Hence, the description is being omitted in the present study, whereas the illustrations are given for the sake of comparison.
Remarks: The species under reference was shifted as a 'form' of obliqua Walker under genus Diacrisia Hübner by Hampson in 1901.The present work deals with the detail study of its male and female genitalic structures which confirms its status as a distinct species.Hence, the original combination of todara Moore with genus Spilarctia Butler has been revived.

Spilarctia castanea (Hampson) comb. nov. (Figure 2)
Hampson in 1901neaHampson, 1893: 9, male, type locality Sri Lanka, type depository NHM, London and examined by the junior author.Hampson was described under genus Diacrisia Hübner byHampson in 1901.Critical examination of its external genitalic structures revealed that it does not conform to the characterization of type species of Diacrisia Hübner.Therefore, the new combination for this species has been proposed by transferring it under Spilarctia Butler.The male genitalia of this taxon has been described and illustrated in detail for the first time.The species has also been recorded for the first time from India.Uncus strongly built, sickle shaped, setosed with fine setae, sclerotized, tip pointed; acrotergite well developed; fenestrula absent; tegumen longer than uncus, u-shaped; vinculum shorter than tegumen, v-shaped; saccus well developed.Valvae with costa narrow and weakly sclerotized; sacculus sclerotized, produced to an outgrowth towards distal end; harpe+ampulla simple plate like; cucullus rounded; valvula simple, setosed with long setae.Transtilla sclerotized bar like; juxta well developed, plate like; aedeagus long and moderately broad, almost straight; carina penis convex lens like with convex surface bearing small spines; vesica membranous with irroration of small spine, two patches of large spines present; ductus ejaculatorius entering subapically.The above said species bifascia Hampson was shifted under genus Diacrisia Hübner as a 'form' of Diacrisia obliqua Walker by Hampson in 1901.But the detail examination of genitalic structures like shape of uncus, juxta, valvae and aedegus of bifascia Hampson clearly conform that it is better to place this taxa under genus Spilarctia Butler.Therefore, the original status of this species has been revived in the present work and male genitalic structures are discussed and illustrated in detail for the first time.