Dialectica falcata, 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 : 90-94

Dialectica falcata , sp. n.

( Figs 12A–F ; 13A–C )

Material examined. Holotype: ♁, Kenya, Tsavo National Park, 530 m, Taita Discovery Centre , 03°40’S 38°45’E, 13.iv.2002, leg. J. De Prins. Gen. prep. VS551, in coll. RBINS . Paratypes: 1♁, 1♀, Kenya, Taita Discovery Centre, Mwakaramba Tank , 500 m, 02°40’S 38°46’E (B8), 02.iv.2001, leg. J. & W. De Prins. Gen. prep. VS567; 1 ♁, 1♀, Kenya, Tsavo National Park, 530 m, Taita Discovery Centre , 03°40’S 38°45’E, 13.iv.2002, leg. J. De Prins. Gen. preps. VS552 ; 1♀, Kenya, Arabuko Sokoke Forest , 20 km W Gede, 90 m, 03°25’S 039°53’E, 31.iii.2004, leg. J. De Prins. Gen. prep. VS522, in coll. RBINS .

Diagnosis. The new species mostly resembles Dialectica anselmella Guillermet, 2011 , known from Réunion (for illustrations refer to Guillermet 2011, photo 5, fig. 5, 6). The male genitalia of D. falcata are most easily diagnosed by the vesica with two short bands of small spines and more apically with two rows of larger spines. In the female genitalia the new species differs from D. anselmella by (1) two bunches of short spines with short lateral projections at posterior end of ductus bursae, (2) ductus bursae gradually widening towards corpus bursae in its entire length, while in D. anselmella it widened only in the proximal part, and (3) nine signa in the form of sclerotized plates with pointed proximal processes, in D. anselmella there are 8 signa in shape of crossed spines.

Description. Adult ( Figs 12A, B ). Forewing length: 2.9–3.4 mm.

Head: Frons and vertex snowy white, occipital tufts ochreous white. Labial palpus 2.3 times as long as width of head, upcurved, second palpomere white above, pale brown laterally, terminal palpomere pale brown. Maxillary palpus almost straight, nearly as long as width of head, white above, pale brown below. Antenna slightly longer than forewing, scape brownish grey, with small flap ventrally; flagellum brown grey, underside greyish white in basal 1/3.

Thorax: Pale ochreous; tegulae pale ochreous with dark brown anteriorly. Forewing ochreous brown, whitish ochreous markings edged with blackish scales; first large triangular blotch extending on dorsum from near base to 2/5 of wing, its apex narrowly reaching costa; second smaller, trapezoidal blotch beyond middle to 2/3 of wing, its apex very narrowly reaching costa; rather narrow two medially constricted (sometimes interrupted) oblique bands at 4/5 and 5/6; apex with small white spot; apical fringe ochreous brown, subapical dorsal fringe ochreous white between oblique bands, otherwise pale ochreous grey. Hindwing brownish grey, its fringe scales somewhat paler. Fore coxa white, with pale brown apex, fore femur and tibia grey brown, tarsomeres I–II ochreous white with grey-brown medial patch, tarsomere III ochreous white with grey-brown apical patch, tarsomeres IV–V ochreous white; mid femur grey-brown, mid tibia grey-brown with dirty white medial patch, tarsomere I ochreous white with grey-brown medial patch, tarsomeres II–IV ochreous white with-grey brown medial patches, tarsomere V dirty ochreous white; hind femur white with small brown-grey basal, medial patch, hind tibia ochreous white with brown-grey medial patch, tarsomeres I–III ochreous white with grey-brown medial patches, tarsomeres IV–V ochreous white.

Abdomen: Dorsal surface brownish grey; ventral surface white, sterna with greyish brown posterior margins.Male tergite VIII greatly enlarged, with proximal margin strongly sclerotized, mediobasally with a pair of dorsocephalic apodemes that are short and slender. Caudal margin of sternite VII widely notched, with long, apically shortly divided process directed caudally from the middle of notch ( Fig. 12F ).

Male genitalia ( Figs 12C–E ). Tegumen oblong with a blunt apex in ventral view, shortly constricted at basal 1/7; lateral sides well sclerotized, with two pairs of long apical setae and 4 pairs of similar ones on median area of lateral margins. Valva as long as tegumen, dilated basally, gradually narrowing from about 1/2 towards narrow, strongly setose blunt apex; inner surface with two combs, posterior comb placed at basal 3/5, with 30–41 teeth, occupying about 1/3 the length of valva; anterior comb at basal 1/2, with 15–26 teeth, occupying about 1/4 the length of valva; long, slender androconial scales scattered on outer surface of valva near base; a bunch of long scent scales arising from inner surface of valva at about 1/4 from base in a group, and those from both valvae connected with each other by flattened apical parts in form of ovate leaf at back of tegumen. Vinculum short, with long and narrow saccus. Aedeagus 0.8 length of valva, tubular, apically slightly dilated; vesica with two short bands of small spines and more apically with two rows of larger spines.

Female genitalia ( Figs 13A–C ). Papillae anales rather short, obliquely transverse in lateral view, basal margins strongly sclerotized. Apophysis posterioris as long as apophysis anterioris; apophysis anterioris angulated at 1/2, basal part broadened. Ostium small, with lightly sclerotized margins; antrum short, weakly sclerotized; ductus bursae wide, 2 times longer than segment VII, with a group of stout spines and two bunches of spines with short lateral projections in posterior end before antrum; corpus bursae small, oval, with 9–10 signa in the form of sclerotized plates with pointed proximal processes arranged in a ring medially.

Host plant(s). Unknown.

Flight period. Adults on the wing are recorded from late March until mid-April.

Distribution. Known only from south-eastern Kenya.

Etymology. The species name is derived from the Latin ‘ falcata ’ (sickle-shaped) in reference to the shape of apophysis anterioris.

Figures

FIGURE 12. Dialectica falcata sp. nov. A, adult, female, scale bar 1 mm; B, head, frontal view; C, male genitalia, general view (aedeagus removed); D, aedeagus; E, cornuti; F, caudal part of abdominal pelt. A–B, paratype; C–F, holotype, gen. prep. VS551. Scale bar 0.1 mm.

FIGURE 13. Dialectica falcata sp. nov., paratype, female genitalia. A, general view; B, ostium and caudal part of ductus bursae; C, signa, gen. prep. VS522. Scale bar 0.1 mm.