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.