Lactura rubritegula Matson & Wagner, 2017

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 rubritegula Matson & Wagner, 2017 Figs 1, 19, 29, 30, 41, 46, 52, 62, 63, Table 1

Lactura rubritegula Matson & Wagner, 2017: 141. Type locality: Kendall Co., Texas, USA. Type material: USNM, UCMS, TAMUIC

Diagnosis.

Lactura rubritegula can be distinguished from its relative L. basistriga by the prominence of red dorsal scales on the tegula. It lacks the red subcostal dash that can be found in most forms of L. basistriga and L. nalli , and the scattered flecking of red or brown scales characteristic of L. subfervens . Many, but not all, individuals can be distinguished by the basal displacement of the lowermost antemedial spot, somewhat enlarged upper postmedial spot, and the concave arc (open to termen) of the three lower postmedial spots. Female genitalia differ from other Lactura in this treatment in having six or seven coils in the ductus bursae. Unique to the larva of this species is the rusty brown dorsum.

Description adult.

(Figs 1, 19) Forewing length: 9-11 mm (n = 25). Head. Shiny, white decumbent scales over vertex and frons; lower frons sometimes with scattered pink scales. Labial palpus slightly porrect to straight, brick red, subequal to diameter of eye. Antenna filiform, 0.6 length of forewing; shiny, white decumbent scales over scape and basal 2/5, transitioning to admixture of white and red scales; distal 1/5 brick red. Thorax. Predominantly white. Patagium mostly white, but red basally. Tegula with conspicuous basal and medial red scales, similar to L. subfervens . Medial mesothoracic red spot flanked posterolaterally by ellipsoid to bar-like red spots. Coxa and femur with reddish mesal and dorsal surfaces, distal and ventral surfaces mostly white with mixture of both white and red scaling; tibia given more to white scaling; protarsus mostly red, meso- and metatarsus given to more white scaling. Forewing. Pearly white, with seven blood- to mahogany-red spots in oblique antemedial and postmedial series; without scattered dark scales (of L. subfervens ). Antemedial row with three spots; lower spot usually displaced basally and often smaller than middle spot; postmedial series with four spots: uppermost usually larger or subequal to that below it; lower three forming straight line or (more commonly) slightly concave arc open to termen. (These same three spots often form convex arc in L. basistriga and L. nalli due to basal displacement of lowermost spot.) Basal red scaling along costa narrows and ends before antemedial spots. Underside red with white fringe scales. Hindwing. Uniformly light red, above and below, with elongate white fringe scales. 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. Male Genitalia (Figs 29, 30) (n = 2). Uncus strongly down-curved; medially constricted in basal third; distal part cylindrical and tapered, terminating in thorn-like apical spine. Valva elongate-oval, 2.5 × longer than wide, costa concave at distal third; apex broadly rounded; lateral lobe of juxta with 10-20+ thickened spiniform setae. Vinculum narrow, U-shaped, subquadrangular. Aedeagus exceeding length of valva; thickest at midlength; base broadly rounded; apex ca. half width of middle section, ending in concave oblique aperture, subapical thumb-like process absent. Female genitalia (Fig. 41) (n = 2). Papillae anales ca. 4 × longer than broad with dorsal sclerotized rim fused with posterior apophyses. Ductus bursae with 6-8 coils; coil diameter gradually increasing to corpus bursae; anteriormost coil 2 × diameter of posteriormost coil, and subequal to diameter of bursa. Corpus bursae longer than broad with large four-lobed signa; without anterior accessory pouch.

Description of living final instar.

(Fig. 46) Glossy pale green with broad cinnamon-brown middorsal stripe outwardly edged with black that runs through the D1 pinacula; white dorsal/subdorsal stripe running through yellow D2 warts; two, wavy-edged, pale supraspiracular stripes, subequal in width to subdorsal stripe, that extend from T1-A8. Larger primary setae borne from minute white spots (~pinacula). Dorsum with vague, black, transverse intersegmental lines. White D1 pinacula borne from apex of otherwise black warts. D2 seta from white pinaculum at apex of yellow wart with yellow extending down to SD seta. Thin, vague, wavy, pale spiracular stripe immediately ventral to light-orange spiracles, as well as single, white, straight-edged subventral stripe equal in width to supraspiracular stripes.

Distribution and biology.

Lactura rubritegula is known from the Hill Country around San Antonio, Texas, westward to Edwards and Uvalde counties, but its range remains unclarified due to previous taxonomic confusion with L. basistriga and other Lactura (Fig. 52). Its range likely extends into Mexico. Delmar Cain has found larvae feeding on Sideroxylon lanuginosum (this is the only Sideroxylon that occurs at the three known localities for the species). Peak flight of L. rubritegula appears to be tied to spring rains and the availability of new foliage. The moth begins flying, late for a Lactura , i.e., in the second half of April into May, following the flights of L. subfervens and L. pupula at the type locality (Fig. 62).

Remarks.

A comparative assessment of L. rubritegula relative to L. basistriga is provided in Matson and Wagner (2017).