Lactura rubritegula Matson & Wagner

Matson, Tanner & Wagner, David L., 2017, A New Cryptic Lactura from Texas (Lepidoptera, Zygaenoidea, Lacturidae), ZooKeys 711, pp. 141-150 : 141-146

Lactura rubritegula Matson & Wagner sp. n. Figs 1, 3, 5, 7, 9, 10

Diagnosis.

Lactura rubritegula can be easily distinguished from its closest relative L. basistriga by the presence of red tegulae. It lacks the red subcostal dash that can be found in most forms of L. basistriga 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 arcing (open to termen) of the three lower postmedial spots. We have not identified male genitalic characters that are unique to the new species. Females lack the small accessory pouch at the anterior end of the corpus bursae present in L. basistriga (Figs 5, 6) and some other Lactura ; the anterior end of the ductus bursae is coiled six to seven times in L. rubritegula , but only 3-4 times in L. basistriga . Larvae are immediately distinguished from other Texas Lactura by their cinnamon-brown dorsum. In its various forms, the middorsal area of L. basistriga usually shows a green heart line. Supraspiracular stripes in L. rubritegula are about twice the width of those of L. basistriga . In the material that we have for study, the white pinacula are more prominent in L. rubritegula than those of other North American members of the genus.

Description.

Adult male. Forewing length: 9.5-10.5 mm (n=12). Body salmon red. 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 2/5ths, transitioning to admixture of white and red scales; distal 1/5th brick red. Thorax. Predominantly white. Patagium and tegula red basally. Medial mesothoracic red spot flanked posterolaterally by ellipsoid red spots. Coxa and femora with whitish scaling along lower surface, other surfaces and segments brick red. Epiphysis well developed about ¼ protibial length. 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 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 white; paired ventral androconial brush composed of 20-40 white, thin scales hidden in intersegmental area between A5 and A6; second, subdorsal, paragenital androconial tuft of>40 straw-colored scales at base of tegumen. Male genitalia. Uncus basally cordiform; medial and distal part cylindrical, strongly down curved, ending in thorn-like spine. Tegumen lung shaped with strong medial crease. Valva elongated oval, 2.5 × longer than wide, costa slightly concave pre-apically; broadly rounded; outer margin with shorter, thicker scales; lateral lobe of juxta with 6-8+ thickened spiniform setae. Vinculum narrow, U-shaped. Aedeagus exceeding length of valva; thickest at midlength; base broadly rounded; apex about half width of middle section, ending in short knob (Fig. 3). Female. Forewing length. 10-12 mm (n=9). Outwardly undifferentiated from male. Female genitalia. Papillae anales bowed inward, about 4 × longer than wide, with long setae. Apophyses short and not especially well differentiated, approximately equal in length. Antrum thickened, hat shaped. Ductus bursae distally unmodified, anterior 2/3 spiraled into 6-7 tight whirls before entering corpus bursae; four strongly toothed signa arranged into two groups; corpus bursae ellipsoid, lacking anterior accessory pouch.

Description of living final instar.

Glossy pale green with broad cinnamon-brown middorsal stripe outwardly edged with black; white subdorsal and two, wavy-edged, pale supraspiracular stripes extending from T1-A8. Larger primary setae borne from minute white spots (~pinacula). Dorsum with black transverse lines at unions of each segment. White D1 pinacula from otherwise black warts. D2 seta also from white spot at apex of yellow wart with yellow washing 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. Prothoracic shield well differentiated, medially divided, mostly black, although with little pigment deposition along its anterior and lateral margins (Fig. 7). Head black, partially retracted into prothorax.

Type material examined.

Holotype male, dry pinned (Figs 1, 3) TX: Kendall Co., Boerne, D. Cain Home (29°52'51"N, 98°36'51"W), 27 April 2015, David Wagner & Delmar Cain colls., CO1 Barcode DLW-000816 Genitalia slide # TAM-2017-002, Deposited at USNM, Washington D.C., USA. Paratypes adults. (10♂, 9♀): TX: Kendall Co., Boerne, D. Cain Home (29.8808°, -986139°), 26 April 2017 - 02 June 2017, Delmar Cain coll. (3♂, 4♀) (UCMS); TX: Kendall Co., Boerne, D. Cain Home (29°52'51N, 98°36'50"W), 27 April 2015, David Wagner & Delmar Cain colls., Genitalia slide # TAM-2017-004, TAM-2017-001, DLW-000568 (2♂, 2♀) (UCMS); TX: Kendall Co., Boerne, Clear Creek Circle (29°52'51N, 98°36'50"W), 27 April 2015, (ex ova; DLW Lot 2015D60) emerged 27 May 2016, David Wagner & Delmar Cain colls., reared on Sideroxylon celastrinum , CO1 Barcode DLW-000280 (1♂) (UCMS); TX: Edwards Co., 1.3 mi NW Camp Wood (29.6822°, -100.0289°), 23 April 2016, Ann Hendrickson coll., (1♀) (UCMS); TX: Edwards Co., 1.3 mi NW Camp Wood, (29.6822°, -100.0289°), 11-25 April 2017, Ann Hendrickson coll., CO1 Barcode DLW-000817 (3♂) (TAMUIC); TX: Uvalde Co., Concan, 23-27 April 2017, Ed Knudson coll., (1♂, 1♀) (USNM); TX: Kerr Co., 10 mi. W. of Hunt, 20 May 1995, Ed Knudson coll., (1♀) (UCMS).

Other material examined.

Adults. TX: Harris Co., Spring Valley, 28 May 1985, leg. E. Knudson Larvae. TX: Kendall Co., Boerne, Clear Creek Circle (29.8807°, -98.6146°), 11 May 2017, Delmar Cain coll., beaten from Sideroxylon lanuginosum (n=1). TX: Kendall Co., Boerne, 29°52'51N, 98°36'50"W, ex ova from female 27 April 2015, DLW Lot: 2015D60, David Wagner & Delmar Cain colls., (n=6) (UCMS).

Distribution.

Hill Country around San Antonio, Texas, westward to Edwards and Uvalde counties, but range still unclarified due to taxonomic confusion with L. basistriga and other Lactura . A single specimen, seemingly out of range, was taken by Ed Knudson in Harris Co., Texas (Spring Valley). Range likely extends into Mexico.

Etymology.

The new species is named for the extensive red scaling through the basal half of the tegula, much of which is visible from above-red scales immediately distinguish both sexes from other members of the Lactura basistriga group that occur in the Rio Grande Valley and northern Mexico, although similar scaling occurs in L. subfervens .

Biology.

Larvae are specialists on Sideroxylon (formerly Bumelia ) (Family Sapotaceae ). S. lanuginosum is the only Sideroxylon that occurs at the three known localities for the species. Ex ova larvae of L. rubritegula were reared to maturity on S. celastrinum in captivity. Larvae preferred young leaves and rejected (and failed) on older leaves.

Peak flight of L. rubritegula appears to be tied to spring rains and the availability of new foliage. The moth begins flying in the second half of April. The majority of records are centered around the end of April and first half of May following the flights of L. subfervens and L. pupula at the type locality. It is unclear if early June captures represent late emergers or a small facultative second generation. An ex ova larva that was reared from a female taken on 25 April 2015 did not emerge until 27 May 2016.

In captivity the larvae typically feed from leaf undersides. Similar to other members of the genus, larvae emit slimy exudate from their integument; the function of the exudate remains unknown. At least in captivity, we often found feculae adhering to our caterpillars that remained attached until the next molt. Mature larvae spin a dense, red-brown cocoon in leaf litter or over soil. Presumably summer, fall, and winter months are passed as a prepupa.