Dialectica silvana, Sruoga & Prins, 2023

Sruoga, Virginijus & Prins, Jurate De, 2023, New species, new country distribution records, and a new generic combination of Afrotropical Acrocercopinae (Lepidoptera: Gracillariidae), Zootaxa 5285 (1), pp. 75-115 : 94-97

Dialectica silvana , sp. n.

( Figs 16A–F )

Material examined. Holotype: ♀, Kenya, Kakamega Forest , 1575 m, 00°19’N 034°52’E, 31.iii.2003, leg. J. & W. De Prins. Gen. prep. VS519, in coll. RBINS.

Diagnosis. The new species is similar to Dialectica praegemina ( Meyrick, 1917) , known from South Africa (for illustrations refer to Vári 1961, pl. 14, fig. 5; pl. 61, fig. 1; pl. 96, fig. 4). However, the forewing pattern differs mainly by less expressed white spots along the costal margin of the forewing. In female genitalia, strongly spinosed ductus bursae with two long, angled external projections and ostium bursae with sclerotized lateral and proximal margins easily separates D. silvana from D. praegemina .

Description. Adult ( Figs 16A, B ). Forewing length: 4.6 mm.

Head: Frons snowy white with grey brown scales ventrally; vertex and occipital tufts snowy white. Labial palpus 3.3× as long as width of head, upcurved, white, second palpomere grey-brown in apical part, terminal palpomere with some grey-brown scales basally and pale ochreous tip. Maxillary palpus as long as width of head, white intermixed with some dark brown scales. Antennal scape dirty white, with brown-grey flap of scales below; pedicel dark brown-grey, flagellum ochreous grey, underside greyish white in basal 1/3.

Thorax: Snowy white; tegulae dark ochreous brown. Forewing colour orange-brown with white markings outlined by 1–2 rows of dark brown scales; three large triangular white dorsal blotches, first at 1/4 connected to rather wide band along dorsal margin between base and triangle; second smaller triangle at 1/2 from dorsal margin to above midline where it is becomes a narrow inverted triangle reaching costa; third triangle at 4/5 of dorsal margin, connected on dorsal margin with narrow white line from 9/10 on dorsal margin to about 4/5 on costal margin, small white costal spot opposite third triangle; fringe ochreous brown, fringe line dark brown. Hindwing brownish grey, its fringe scales somewhat paler. Fore coxa white, with brown-grey apical patch; fore femur brown-grey, fore tibia brown-grey, with white basal patch; tarsomere I dirty white with brown-grey medial patch, tarsomeres II–III dirty white with brown-grey subbasal patches, tarsomeres IV–V dirty white; mid femur brown-grey, with dirty white apical patch, mid tibia white, with brown-grey basal, subapical and apical patches, tarsomere I dirty white with brown grey medial patch, tarsomeres II–III dirty white with brown-grey subbasal patches, tarsomeres IV–V dirty white; hind femur white with small brown-grey medial patch, hind tibia white, with pale brown-grey apical and large medial patches and dark brown-grey apical patch, tarsomere I dirty white with pale brown grey basal and apical patches, tarsomeres II–III dirty white with brownish grey apical patches, tarsomeres IV–V dirty white.

Abdomen: Pale brownish grey dorsally and white ventrally, sterna with pale brownish grey anterior margins.

Male. Unknown.

Female genitalia ( Figs 16C–F ). Papillae anales rather short, obliquely transverse in lateral view, basal margins strongly sclerotized. Apophysis posterioris about 0.7 the length of apophysis anterioris; apophysis anterioris with about 30 degrees angle at basal 1/3. Ostium bursae with sclerotized lateral and proximal margins; antrum short, weakly sclerotized. Ductus bursae long and narrow, 3× longer than segment VII, with tiny internal spines in all length and with a wide band of stout spines from 2/3 length of ductus bursae until corpus bursae and two scobinate horns at 2/3 length of ductus bursae. Corpus bursae oval, with 9 signa in form of sclerotized plates with pointed proximal processes arranged in a ring medially, two signa are smaller than other 7.

Host plant(s). Unknown.

Flight period. The only known specimen was captured in late March.

Distribution. Known only from type locality in south-eastern Kenya.

Etymology. The specific name is from the Latin ‘ silvanus ’ (associated with forest), in reference to the collecting site of the holotype.

Remarks. The antennae of the holotype are partly broken and the forewings are slightly abraded, therefore the description is approximate.

Figures

FIGURE 16. Dialectica silvana sp. nov., holotype, female. A, adult, scale bar 1 mm; B, head, frontal view; C, caudal part of genitalia; D, ductus bursae; E, proximal part of ductus and corpus bursae; F, signa. Gen. prep. VS519. Scale bar 0.1 mm.