Tactusa sumatrensis Fibiger, 2010

FIBIGER, MICHAEL, 2010, Revision of the Micronoctuidae (Lepidoptera: Noctuoidea) Part 3, Taxonomy of the Tactusinae, Zootaxa 2583 (1), pp. 1-119 : 17

Tactusa sumatrensis Fibiger , new species

( Plate 1 , figure 4; male genit. plate 12, figure 2)

Material examined. Holotype: male, Indonesia, N Sumatra, 28 km S. P. Siantar near Tigadoluk, H.W. II, 02’45’52N, 99’58’20E, 10.ii.2002, 1050 m, leg. & genit. prep. 4542 M. Fibiger. Coll. MF, to be deposited in ZMUC.

Paratypes: 3 males: 2 males with same data as holotype, but 4.iii.2002, genit. preps 4537 and 4540 M. Fibiger ; 1 male with same data as holotype, but H.W. III, near Prapat, 18.ix.1982, genit. prep. 4651 M. Fibiger. Colls ZSM and MF .

Taxonomic notes. T. sumatrensis is a member of the T. sumatrensis species-group, which has a blackish brown quadrangular patch between the antemedial and postmedial lines.

Diagnosis. Imago (external). Wingspan: 12–13 mm.

Forewing: ground colour yellowish interrupted by brownish cross shades, especially medial shade.

Crosslines: only terminal lines visible, marked by dark-brown spots, subterminal line indicated by black patches outlined inwardly by yellow.

Reniform stigma: present but weakly marked; by lower outer edge of costal quadrangular patch.

Hindwing: dark grey, with indistinct discal spot.

Underside: unicolorous grey.

Male genitalia. Tegumen: narrow, considerable narrower than vinculum and saccus.

Vinculum: strongly built.

Saccus: short; strongly built, broadly U shaped.

Fultura superior: membranous.

Valva: asymmetrical; right side longer and broader.

Ampulla: more or less forming a cross with axis of valva; elongated and narrow; convex by valva; distal edge concave; boomerang shaped, with more pointed dorsal arm 1.5 times shorter than ventral arm (apo.).

Digitus: absent.

Juxta and anellus plate: totally fused, with hole for phallus; slightly asymmetrical.

Phallus: long; clockwise coiled; tapered towards apex; coecum upturned; with humps subbasally; almost straight until heavy coil subterminally; subapically with a prominent, long spine; some species with a shorter straight cylinder.

Vesica: without cornuti.

Female genitalia. Unknown.

Differential diagnosis. T. sumatrensis differs from T. parasumatrensis in greyish-yellow ground colour of forewing, presence of antemedial and postmedial lines and in less dark subterminal area; in male genitalia, left valva longer than right one (reverse in T. parasumatrensis ), dorsal arm of ampulla wider but ventral arm 1.5 times longer ( 2.5 in T. parasumatrensis ), phallus more sharply angled, with a broader and more curved spine and tip of vesica less pointed. Both differ from other Micronoctuidae from SE Asian and Oriental regions in boomerang-shaped ampulla, upturned coecum, and spine of phallus.

Distribution. Known from one specimen from N Sumatra.

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.