Americerura St Laurent and Goldstein, 2023
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publication ID |
https://doi.org/ 10.1093/isd/ixad004 |
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persistent identifier |
https://treatment.plazi.org/id/E247440E-C819-360E-FCF0-FF6807E5F93E |
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treatment provided by |
Felipe |
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scientific name |
Americerura St Laurent and Goldstein |
| status |
gen. nov. |
Americerura St Laurent and Goldstein , gen. nov.
( Figs 11–14 View Fig View Fig View Fig View Fig ) (urn:lsid:zoobank.org:act:CFE2F544-A9FD-4872-B026-
D7D7501E68FD)
Type species.
Cerura scitiscripta Walker, 1865: 408 View in CoL , by present designation.
Etymology.
The name is a combination of ‘America’ and ‘ Cerura ’ referencing that this is the only American contingent of a principally Old World clade containing Cerura and its closest relatives. The name is feminine.
Diagnosis.
As is typical of most cerurines, adult Americerura are primarily black and white, with the white of the wings deriving from lustrous, reflective scales in most species. Antennae are feathery, bipectinate to the tips in both sexes, with those of males bearing longer pectinations. The male genitalia ( Fig. 12 View Fig ) are rather simple, and within Cerurinae , most similar to the related Old World genera Cerura and Kamalia , on the basis of smoothly upwardly curving rounded valvae, an ellipsoidal vinculum, a short but well-sclerotized blunt uncus, and heavily sclerotized, short, curled fingerlike socii. Typically, Americerura valvae are narrower and more widely splayed than in Cerura , and the phallus and eighth sternite less robust than in Kamalia . The phallus is variable, but usually pointed. The eighth sternite ( Fig. 13 View Fig ) nearly always bears a trifid plate forming a ‘W’, a similar trait seen in Kamalia . Female genitalia are generally simple ( Fig. 14 View Fig ), without a heavily sclerotized ostium, prominent antevaginal plate, or a notable differentiation between the vaginal plates. Most species of Americerura are also smaller moths, in general, and thus genitalia are smaller overall than those of the large Cerura and Kamalia .
Americerura may be confused with some of the paler Furcula species in North America where they are sympatric, but Furcula can be easily recognized by the presence of dark, metallic scales on the thorax that give it a characteristic sheen. Americerura could also continue to be confused with members of Tecmessa s.l. as they have been since Schintlmeister (2013), but the genitalia of Tecmessa s.l. are distinct, with narrower valvae, a narrower phallus, and a less modified eighth sternite lacking a W-shaped structure. The antennae provide an immediate clue to their differentiation given that in Tecmessa s.l. they are longer and less feathery. Americerura also lack the beard-tufts of the head and the cteniophores of some species of Tecmessa s.l. as well.
All known last instar Americerura caterpillars are green or yellow, with a variably shaped and colored dorsal saddle on the thoracic and abdominal segments, and broad thoracic segments into which the head can partially retract. Usually, the head is edged by red or pink on the prothoracic segment, with false eyespots flanking the head on each anterior corner of the prothorax. All species of Americerura have stemapods with eversible internal whips that are yellow, orange, or red (or some combination). Americerura caterpillars are only likely to be confused with Furcula , and only in Canada, the U.S.A., and Mexico where the genera co-occur. Furcula caterpillars generally lack colored prothoracic margins around the head (and are less contrasting if present), have darker stemapods, and are generally much more mottled in overall appearance.
Description.
Adult. Male. Head: Width more than half that of thorax, frons coloration white, gray, black or bicolored black and white with black ventrally, eyes large, naked, occupying more than 2/3 area of head, eyes usually bordered posteriorly by dark brown or black scales; labial palpus reduced, not extending beyond frons, two-segmented, coloration usually as for frons; haustellum very short, not typically visible, antennal scape scaled in erect tuft of white or gray scales, antennae brown to black with white and/or black scales coating dorsal surface, bipectinate to tip with rami increasing in length from antennal base to roughly half antennal length where rami length abruptly become shorter, remaining short until terminus. Thorax: overall patterning gray or black and white, prothorax often with black margin or fully clothed in black scales, mesothorax and metathorax with white ground color and black spots; thickly scaled. In species with darker (not white) forewings, thorax tends to approximate darker wing ground color. Legs mostly concolorous with thorax, basal segments black and white, tarsi typically black. Tibial spurs thin, short, clothed in fine white scales, in formula 0-2-2. Tarsal claws simple. Forewing length 11–24 mm (measured from edge of thorax to wing tip), wingspan 23–46 mm (measured wing tip to wing tip); subtriangular, outer margin weakly convex, apex not pronounced. Forewing dorsum ground color ranging from gray ( A. duonumennia [ Dyar, 1912]), gray-brown ( A. annulifera [ Berg, 1878]), to off-white or lustrous immaculate white (all other species). Antemedial, medial, and submarginal ground color concolorous. Overall forewing pattern variable but always with some combination of wavy or zigzagging lines ranging from extremely reduced or nearly absent (e.g., A. splendens [Jones, 1908], A. candida [ Lintner, 1878]) to nearly covering the forewings (some forms of A. scitiscripta ). Antemedially proximal to thorax usually a weakly defined transverse black line present, antemedial band usually present, may range from complete and filled with light blue-gray scales to incomplete or replaced by yellow splotches. Wing with variable number of zigzagging black lines medially. Postmedial line usually most well-defined line of wing, typically thickest subapically with a secondary outer submarginal line paralleling postmedial line to varying degrees, both postmedial and submarginal lines sharply crenulate, forming points at vein intersections. Discal spot usually absent but may be weakly defined as black mark, thick markings usually present along costa and anal angle. Most species bearing black markings between veins along wing margin, with wing fringe further invaded by black scales aligned with intervenular marks along wing margin. Forewing venter usually lacking markings but may be variously smudged by darker scales, particularly subapically. Hindwing dorsum generally devoid of markings, although dark discal marks, marks at anal angle, and along margin may be present; hindwing coloration ranging from gray, blackish, to pure white. Hindwing venter as for hindwing dorsum, usually without marks except along costa. Frenulum a single bristle. Wing venation as for other Cerurinae , but forewing bearing a small accessory cell and radial veins arising from its apex. Abdomen: Clothed in white, gray, or black scales, separation between abdominal segments usually poorly defined but may be delimited by margins of hoary scales; terminal segment often with lighter scales. Eighth sternite ( Fig. 13 View Fig ) either with W-shaped sclerotization (lacking the medial prong in A. bratteata ( Draudt, 1932)) or with more complex five-pronged structure ( A. rarata [Walker, 1865] and A. tehuacana [ Draudt, 1932]). Central prong variable in width and length depending on species. Genitalia ( Fig. 12 View Fig ) (n = 25) simple in overall structure, with ovoid, weakly connected vinculum ventrally. Tegumen weakly defined. Uncus simple, bifid, or distally widened, thickly sclerotized, blunt, covered in setae. Socii simple, fingerlike, upcurved and heavily sclerotized, thickness variable, externally ranging from smooth to rugose. Gnathos absent. Valvae simple, rounded to somewhat acutely angled apically. Juxta typically a thin sclerotized strip, partially fused to phallus. Phallus somewhat variable, but typically broadest mesally, downcurved distally, with sharp apex, vesica thin, simple, bag-like without cornutus.
Female. Sexual dimorphism in general not greatly pronounced. Head: As for male but antennae with shorter rami overall, rami longest basally and becoming gradually shorter along antennal length to apex. Thorax: As for male. Forewing length 18–26 mm, wingspan 23–50 mm; subtriangular, outer margin weakly convex, apex not pronounced. Forewing dorsum as for male but wing broader. Hindwing dorsum gray, gray-brown to black, rarely white (e.g., A. rarata ). Hindwing venter as for hindwing dorsum, usually without markings. Frenulum with numerous tightly packed bristles. Abdomen: As for male but bulkier, terminal segments with corethrogyne in some species. Eighth sternite simple, lacking the W- or five-pronged structure present in males. Genitalia ( Fig. 14 View Fig ) (n = 4) simple; tergite eight a narrow, sclerotized bar. Apophyses anteriores reduced to thick prominences; apophyses posteriores thin, relatively short, not extending well beyond margin of eight, if at all. Antevaginal plate a simple sclerotized bar; ostium a narrow longitudinal opening or more circular; postvaginal plate either a simple sclerotized region or forming more of a sclerotized pocket. Ductus bursae indistinct; corpus bursae thin, bag-like, lacking signa, smaller or only slightly larger than remaining genitalia complex. Papillae anales broad, covered in long, fine setae.
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