Lactura pupula ( Huebner )

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 pupula ( Huebner) Figs 22, 26, 31, 40, 44, 50, 52, 54-56, 63, Table 1

Eustixis pupula Hübner, [1831]: 24. Type locality: Georgia, USA. Type material: presumably lost

Eustixis leata Geyer, 1832: 5. Type locality: Unknown. Type material: not examined

Mieza igninix Walker 1854: 527. Type locality: St. John’s Bluff, E. Florida, USA. Type material: not examined

Enaemia crassivenella Zeller 1872: 563. Type locality: Texas, USA. Type material: not examined for this study, but seen earlier by Miller ( Miller and Hodges 1990)

Enaemia crassinervella Slosson, 1896: 86; misspelling

Notes.

Lactura pupula was first described as Eustixis pupula in vol. 3 of Hübner’s Zuträge zur Sammlung exotischer Schmetterlinge (1827-1831). The original description was published subsequent to Hübner’s death, and the approximate date of description has been inferred to be 1831 ( Heppner 1997). The original description is vague, weakly informative, and the taxonomy confusing. The type is presumably lost; however, the illustration in Hübner’s manuscript is unambiguous, and assignable to L. pupula as recognized in this work. Years prior, Hübner (1823) gave the name Eustixia pupula to the spotted peppergrass moth, a well-known crambid. Both Eustixia pupula and Eustixis pupula were described from North America, spelled similarly, and both of their descriptions contain the Latin phrase, " Phalaena vera , Lithosia geometriformis ." It is debated to what extent this is intentional and whether Hübner considered the two congeners. Whatever the case, Eustixia pupula and Eustixis pupula are entirely different moths (representing two different superfamilies) and each name remains available.

A few decades later Walker (1854), established the generic names Lactura and Mieza . Both Mieza igninix and Eustixis laeta were placed in the latter genus and considered subjective synonyms of Eustixis pupula ( Walsingham 1914) ( Nye and Fletcher 1991). In literature, Eustixis is largely ignored, perhaps because of its near homonymy with Eustixia ; Mieza as well became infrequently used. All authors after Walsingham (1914) used Lactura , by reason of page priority in Walker (1854) and Mieza has since been suppressed ( Heppner 1997) ( ICZN 1999).

Enaemia crassivenella (Zeller, 1872) and Enaemia crassinervella (Slosson, 1896) are both synonyms of L. pupula - Slosson (1896) was undoubtedly referring to " crassivenella " and " crassinervella " was simply a lapse in spelling.

Diagnosis.

Forewing pattern instantly distinguishes this species from its congeners. The most notable difference is the black streaking along the veins of the forewing, and two oblong antemedial spots and three oblong postmedial spots in the lower half of the forewing. The postmedial spots are arranged in a triangular pattern with the lower distal spot touching the inner margin. Female genitalia have 9-10 distal spirals in the ductus bursae. The larva's orange verrucae on white to orange addorsal stripes distinguishes it from all other Nearctic Lactura .

Description adult

(Fig. 22). Forewing length: 9-13 mm (n = 231). Head. Light red to orange over vertex transitioning to white over frons. Labial palpus slightly porrect to straight, brick red at base and black apically, length subequal to eye diameter. Antenna filiform, 0.6 length of forewing; shiny, white above, fuscous below. Thorax. Patagium mostly white, with black basal scales forming contrasting collar behind head. Tegula with small ventral black basal patch; white medially and shiny black apically. Large medial mesothoracic and metathoracic black spots. Coxa and femur with red dorsal surface and light red to pale white ventral and lateral 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. White with black scales over veins; black scaling extending around apex and terminating about tornus; variable in thickness. Two oblong antemedial spots and three oblong postmedial spots in lower half. Postmedial spots arranged in triangular pattern with lower distal spot elongate and touching inner margin. Costal margin black along basal 1/3 of wing. Underside light red. Fringe scales light red, rarely with admixture of black scales. Hindwing. Uniformly light red to dark orange, above and below, with concolorous fringe scales. Abdomen. Dorsum and sides brick red; venter rusty white. One pair of subventral intersegmental hairpencils (consisting of 40-60 androconial scales) between A7 and A8 (Fig. 31). Male Genitalia (Fig. 26) (n = 7). Uncus strongly down-curved; basally quadrangular and medially constricted through basal third; cylindrical, tapering to apex, ending in apical spine. Valva elongate-oval, ca. 2 × longer than wide, concave along distal third of costal margin; broadly rounded at apex; lateral lobe of juxta with 20-30+ setae, similar to L. atrolinea , but setae shorter and bearing less robust spiniform setae than those of other congeners. Vinculum narrow, U-shaped, subquadrangular. Aedeagus cylindrical, exceeding length of valva; base broadly rounded; apex with broad concave aperture and thumb-like process twice as long as wide. Female genitalia (Fig. 40) (n = 3). Papillae anales ca. 3.5 × times longer than broad with dorsal sclerotized rim fused with posterior apophyses. Ductus bursae with 9-11 coils, posterior two coils more open and extended than anterior coils; diameter mostly uniform; coil diameters more or less uniform with anteriormost coil slightly larger than others. Quadrate signa reduced in size compared to other species treated here; lobes fused in two of three preps. Corpus bursae without anterior accessory pouch.

Description of living final instar

(Figs 44, 50). Ground color pale and mostly unpigmented to mint green, translucent below spiracles. Thin, white to orange middorsal stripe, edged with thick addorsal stripe; prominent white to orange dorsal stripe with orange verrucae that bear D1 and D2 setae; verrucae on A8 more pronounced than others. Thick black dorsolateral stripe divided by white pinstripe on T2-A8. Thick, white supraspiracular stripe best developed on T3-A8. Spiracular stripe thin and white; interrupted by light orange spiracles. The extent of orange coloration is reduced in larvae from Texas, where orange is mostly restricted to the thorax and A7-A9, and the stripe running through the dorsal verrucae is more given to white than orange.

Distribution and biology.

Lactura pupula occurs in woodlands, thickets, scrublands, back dune and coastal strand communities, and along forest edges of central Texas northward in Midwest to Nebraska and Illinois, and eastward to South Carolina and the whole of Florida (Fig. 52). The moth flies from February to October (southward) and is often abundant during its peak flight in March and April in Florida. Southward it is multivoltine, especially in southern Florida where it flies nearly year-round (Figs 54-56). Our host plant records are from gum bully ( Sideroxylon lanuginosum ) and tough bully ( Sideroxylon tenax ); Kimball (1965) also lists saffron plum ( Sideroxylon celastrinum ). Larvae co-occur on the same hostplants with those of L. subfervens over much of its range.

In central and west-central Texas, larvae show a reduction in the amount of dorsal orange maculation. A close relative of L. pupula , based on CO1 data in BOLD (BOLD: ACN5528), occurs in Tamaulipas, Mexico. It would be worthwhile to do more sampling in south Texas and northern Tamaulipas to better delineate the ranges of the two moths. Lactura pupula is rapidly expanding its range westward in Texas. In 2019, the first records of adults were made in Austin (Travis County), Boerne (Kendall County), and Camp Wood (Edwards County)-all at sites that have been regularly sampled over the past decade. Larvae were found in great numbers in the first two of these counties in April of this year.