Tactusa schnacki Fibiger, 2010

FIBIGER, MICHAEL, 2010, Revision of the Micronoctuidae (Lepidoptera: Noctuoidea) Part 3, Taxonomy of the Tactusinae, Zootaxa 2583 (1), pp. 1-119 : 18-19

Tactusa schnacki Fibiger , new species

( Plate 1 , figure 5; male genit. plate 12, figure 4)

Material examined. Holotype: male, India NE, Assam, Khasis , -. viii.1894, genit. prep. 3733 M. Fibiger, coll. BMNH.

Taxonomic notes. T. schnacki is a member of the trigonifera species-group, which has a blackish triangular or quadrangular patch between the antemedial and postmedial lines, the typical Tactusa ampulla and a prominent, long, heavily sclerotised anellus that is totally fused to juxta.

Diagnosis. Imago (external). Wingspan: 12 mm.

Forewing: narrow, pointed at apex; ground colour brownish, darker by costal patch in medial area and in subterminal area.

Crosslines: only terminal line, marked by interneural black spots.

Reniform stigma: well marked; white.

Hindwing: dark grey with indistinct discal spot.

Underside: unicolorous grey.

Male genitalia. Tegumen: narrow.

Vinculum: strongly built.

Saccus: short; strongly built, broadly U shaped.

Fultura superior: membranous.

Valva: asymmetrical; left side broader and with one large ‘window’ (apo.).

Ampulla: forming a cross with axis of valva; slightly asymmetrical, ventral arm much larger than dorsal arm.

Digitus: present; humplike (apo.).

Juxta and anellus plate: fused; anellar plate triangular, heavily sclerotised.

Phallus: S shaped, with a prominent plate by ductus ejaculatorius and with two carina spines (apo.). Vesica: cylindrical, with small subbasal spined patch and tiny apical cornutus.

Female genitalia. Unknown.

Differential diagnosis. T. schnacki does not resemble T. trigonifera in external characters, but does so in several features of genitalia, e.g., asymmetrical ‘windows’ in left sacculus, triangular anellus, presence of a digitus, and two carina spines. It differs from other Micronoctuidae from SE Asian and Oriental regions in most of autapomorphies given under T. trigonifera below.

Distribution. Known from a single specimen from NE India, Assam.

Figures

PLATE 1. Figures 1–7. Tactusa species, adults. 1, T. major, female holotype, Thailand N, Chiang Mai; 2, T. rima, male holotype, Vietnam N, Vinh Phuc; 3, T. sine, male holotype, Vietnam N, Da Lat; 4, T. sumatrensis, male holotype, Indonesia, North Sumatra; 5, T. schnacki, male holotype, India NE, Assam; 6, T. parasumatrensis, male holotype, Indonesia, North Sumatra; 7, T. trigonifera Hampson, 1898), male holotype, India NE, Assam.