Lythria (Lythria) Hübner, [1823]

Makhov, I. A., Gorbunov, P. Yu. & Lukhtanov, V. A., 2024, Lythria (Microlythria subgen. nov.) venustata Staudinger, 1882 (Lepidoptera: Geometridae): distribution and description of the female, with a brief review of the genus, Zootaxa 5448 (1), pp. 29-48 : 38-40

Lythria (Lythria) Hübner, [1823]

Type species. Phalaena purpuraria Linnaeus, 1758 .

Diagnosis. In male, the vinculum is deeply concave ventrally, with the pointed dorso-distal corners; the valva bears a distal membranous part (valvula), the valva-genital segment articulation is flexible; the juxta and sclerotized anellus are absent; sclerotized tegumen is not developed; in female, the corpus bursae without signum.

Species included. L. (L.) cruentaria ( Hufnagel, 1767) ; L. (L.) sanguinaria ( Duponchel, 1842) ; L. (L.) purpuraria ( Linnaeus, 1758) and L. (L.) plumularia ( Freyer, 1831) .

Identification key to Lythria species

Wing pattern:

1. Forewing pattern dark (dark brown or purple brown), contrasting with dark cream or beige ground colour, basal area markedly darkened........................................................................................... 2

– Ground colour of forewing yellowish orange to brownish yellow; pattern reddish, often with olive-grey scales, basal area barely darkened........................................................................................... 3

2. Hindwing without submarginal fascia; fringes of both wings dark brown, almost black (Pl. 1: 1a–1c)...... L. (M.) venustata

– Hindwing with dark submarginal fascia or its distinct trace reaching costal margin; fringes of both wings dark reddish ( Pl. 2 : 5a–5h)............................................................................... L. (L.) plumularia

3. Medial fascia of forewing commonly reduced to a costal spot, at equal distances from antemedial and postmedial fasciae, never fused with them ( Pl. 2 : 4a–4i)............................................................. L. (L.) purpuraria

– Medial fascia of forewing usually present, well developed, sometimes confluent with antemedial fascia................ 4

4. Postmedial fascia of forewing continuous; medial fascia of forewing usually closer to postmedial one or confluent with that; antemedial fascia commonly broad and reaches veins Cu 2 (occasionally transverse fasciae absent) (Pl. 1: 2a–2o)................................................................................................. L. (L.) cruentaria

– Postmedial fascia of forewing usually broken into a row of reddish dashes or spots on veins; medial fascia not fused with postmedial one; antemedial fascia often marked on costa only (Pl. 1: 3a–3d)....................... L. (L.) sanguinaria

Genitalia structure:

1. In male ( Figs 7A–7F ) valvae and genital segment articulated rigidly, distal membranous part of valva (valvula) absent, juxta well developed; in female ( Fig. 8B ) corpus bursae with rhombic lamellar signum...................... L. (M.) venustata

– In male valvae-genital segment articulation flexible, distal membranous part of valva (valvula) developed, juxta not developed; in female signum absent................................................................................ 2

2. In male vesica with a single cornutus, valva roughly rectangular, valvula long and narrow; in female lamella antevaginalis not developed, ductus bursae distinctly narrower than posterior part of corpus bursae................................... 3

– In male vesica with two cornuti, valva roughly triangular, valvula short, rounded sack-like; in female lamella antevaginalis well developed, sclerotized, ductus bursae equal in width with posterior part of corpus bursae or broader.................... 4

3. In male ( Figs 7G–7I ) coecum of aedeagus swollen, cornutus smaller than in L. sanguinaria ; in female ( Figs 8C, 8E ) ductus bursae long, almost equal in length to broader posterior part of corpus bursae......................... L. (L.) cruentaria

– In male ( Figs 7J–7L ) coecum of aedeagus not swollen, cornutus longer and stouter than in L. cruentaria ; in female ( Fig. 8D ) ductus bursae short, no longer than ½ length of broader posterior part of corpus bursae............... L. (L.) sanguinaria

4. In male ( Figs 7O, 7P ) valva short: length of its costal margin approximately equal to its greatest width; in female ( Figs 9A–9C ) posterior edge of lamella antevaginalis not straight: clearly round or with distinct medial projection (often pointed apically), ostium C-shaped....................................................................... L. (L.) purpuraria

– In male ( Figs 7M, 7N ) valva longer: length of its costal margin clearly exceeding its greatest width; in female ( Figs 9D, 9E ) posterior edge of lamella antevaginalis almost straight, without any projections, ostium not C-shaped.... L. (L.) plumularia

Figures

FIGURE 7. Male genitalia of Lythria species. A–F—L. (M.) venustata; G–I—L. (L.) cruentaria; J–L—L. (L.) sanguinaria; M, N—L. (L.) plumularia; O, P—L. (L.) purpuraria. A, E, H, L—genital segment (ventral view) in its natural position; B, G, J, M, O—ditto, unfolded position; C—ditto, lateral view; D, F, I, K, N—phallos, lateral view; P—phallos, ventral view. p.-l. pr. tg.—postero-lateral projections of tegumen.

FIGURE 8. Female genitalia of Rhodometra sacraria and Lythria species, ventral view. A—Rhodometra sacraria; B—L. (M.) venustata; C, E—L. (L.) cruentaria; D—L. (L.) sanguinaria.

FIGURE 9. Female genitalia of Lythria species, ventral view. A–C—L. (L.) purpuraria; D, E—L. (L.) plumularia.

PLATE 2. 4a—Lythria (Lythria) purpuraria: [Kazakhstan] Semirechye, Usek, Taldy loc. in West of Tyshkan, ½.VI.1915, mat. of V. Kavrigin.