Lactura atrolinea (Barnes & McDunnough, 1913)

Matson, Tanner A., Wagner, David L. & Miller, Scott E., 2019, A Revision of North American Lactura (Lepidoptera, Zygaenoidea, Lacturidae), ZooKeys 846, pp. 75-116 : 75

Lactura atrolinea (Barnes & McDunnough, 1913) Figs 18, 25, 32, 35, 39, 47, 53, 57, 63, Table 1

Mieza atrolinea Barnes and McDunnough, 1913: 142. Type locality: San Benito, Texas, USA. Type material: USNM

Diagnosis.

Lactura atrolinea is easily distinguished by its larger size and nearly continuous series of black antemedial and postmedial spots. The tegula is black apically as are the spots over the thorax; the forewing has a thin black subcostal dash. In females the ductus bursae has five or six coils anteriorly. The larva displays attractive, metallic blue, dorsal warts that unmistakably separate this species from its co-occurring Texas congeners.

Description adult.

(Fig. 18) Forewing length: 9-13 mm (n = 138). Head. Vertex white with paired, addorsal, salmon scale patches; frons with shiny white decumbent scales. Labial palpus slightly porrect, brick red at base and black at terminus, subequal to diameter of eye. Antenna filiform, 0.6 length of forewing; shiny, white decumbent scales over scape and basal 2/5, transitioning to fuscous with scattered whitish scales; distal 1/5 brick red. Thorax. Predominantly white. Patagium white with a few red basal scales. Tegula with small ventral black basal patch; white medially and shiny black apically. Prothorax with lateral pair of black spots, but these sometimes obscured by patagium. Coxa and femur with red dorsal surface and light red to pale white outer and ventral surfaces; procoxa with basal mixture of red and black scales; pro- and mesotibia and pro- and mesotarsus black or fuscous dorsally and fuscous red ventrally; metatibia light red; metatarsus fuscous red. Forewing. Pearly white, with oblique series of black antemedial and postmedial spots. Spots nearly contiguous to fused. Antemedial row with three spots; lower spot largest and rendering row convex with respect to base of forewing. Postmedial series with heavy black dash approximately 1/2 width of forewing (continuous but narrowing anteriorly); smaller spot above. Inconspicuous black spot near tornus. Black, basal, subcostal dash similar in size and placement to red subcostal dash in L. basistriga . Basal black scaling along costa narrows and ends before antemedial spots. Fringe scales white. Underside red. Hindwing. Uniformly light red to orange with white fringe scales. Underside of hindwing paler than those of underside of forewing. Abdomen. Dorsum and sides brick red; venter rusty white. Two pairs of subventral intersegmental hairpencils (with 40-60 androconial scales) inserted between A6 and A7, and A7 and A8 (Figs 32, 35). Roseate cluster of elliptic scales, 5 × longer than broad, located anterior to spiracle in intersegmental folds, much more pronounced than in other Texas congeners. Hairpencils and roseate scale clusters more extensive between A7 and A8 than between A6 and A7. Male Genitalia (Fig. 25) (n = 6). Uncus more robust than congeners, strongly down-curved and tapering, strong medial constriction in basal third, ending in short thorn-like apical spine. Valva elongate-oval, 2 × longer than wide, costa concave along distal third; broadly rounded at apex; outer margin with shorter, thicker scales; lateral lobe of juxta similar to L. pupula , but more sclerotized and prominent, with 20-30+ spiniform setae. Vinculum narrow, U-shaped, subquadrangular. Aedeagus cylindrical, exceeding length of valva; base broadly rounded; apex with gaping concave aperture and subapical thumb-like process twice as long as wide. Female genitalia (Fig. 39) (n = 4). Papillae anales ca. 4 × longer than broad with dorsal sclerotized rim fused with posterior apophyses. Ductus bursae with five or six coils; coils more open than other treated species; posterior two coils more open and extended, with corrugated surface; remaining (anterior) coils tightly bound with little to no surface corrugation. Corpus bursae longer than broad; four lobes of signa large with dentate interior projections; teeth widely spaced (similar to those of L. basistriga ). Corpus bursae with anterior accessory pouch with broad opening.

Description of living final instar.

(Fig. 47) Ground color yellow to lime green. D1 and D2 setae borne from metallic blue warts. Middorsum with yellow middorsal stripe; green addorsal stripe running through D1 wart; the latter bound laterally by white pinstripe. Doubled, black dorsal/subdorsal stripe running through larger D2 wart. Supraspiracular area broadly yellow, transitioning to green through spiracular region. Light blue SD1 pinacula positioned directly above spiracles on A1-A8; these connected by thin, wavy, often broken lateral yellow line. A thicker, continuous, stripe runs just below the tan-yellow spiracles.

Distribution and biology.

Lactura atrolinea inhabits the mesic woodlands, coastal scrub, and palm forests of south Texas, southward into Mexico. Breeding populations are known from coastal areas of Texas from Fort Bend to Cameron counties (Fig. 53). What may represent strays have also been taken from the south-central Texas counties of Medina, Live Oak, and Duval. Multiple generations each year with peak activity tied to early spring (March to May) and the fall rainy periods (September into November) (Fig. 57). Larvae feed on saffron plum ( Sideroxylon celastrinum ); caterpillars and adults are sometimes common in the Sabal Palm Sanctuary near Brownsville, Texas.