Herpetogramma sphingealis Handfield and Handfield

Handfield, Louis & Handfield, Daniel, 2011, A new species of Herpetogramma (Lepidoptera, Crambidae, Spilomelinae) from eastern North America, ZooKeys 149, pp. 5-15 : 8-13

Herpetogramma sphingealis Handfield and Handfield sp. n. Figs 1, 2, 811

Type material.

Holotype ♂. Rougemont Mountain, Rougemont, Québec (45°28'026"N, 73°04'029"W), 29.vii.2008, Daniel Handfield, MDH006041, CNC type No. 23981. CNC. Paratypes 83 ♂, 24 ♀: Mont-Saint-Hilaire, Québec, 20.vii.2003 (1 ♂), 20.vii.2008 (1 ♂), Louis Handfield; Otterburn Park, Bosquets Hudon, Québec, 31.vii.2009 (2 ♂), 5.viii.2008 (2 ♂, 2 ♀), Louis Handfield; Rougemont, mountain, Québec, 11.vii.2008 (1 ♂), 16.vii.2008 (2 ♂), 19.vii.2009 (1 ♂), 21.vii.2004 (1 ♂), 21.vii.2008 (5 ♂), 23.vii.2009 (3 ♂), 24.vii.2008 (2 ♂, 2 ♀), 25.vii.2008 (13 ♂, 3 ♀), 27.vii.2008 (5 ♂, 5 ♀), 28.vii.2009 (3 ♂, 1 ♀), 29.vii.2008 (10 ♂, 5 ♀), 30.vii.2009 (3 ♂), 1.viii.2008 (3 ♂), 3.viii.2009 (5 ♂, 2 ♀), 5.viii.2009 (4 ♂, 1 ♀), 7.viii.2009 (1 ♂), Louis Handfield; 21.vii.2004 (4 ♂), Daniel Handfield, 29.vii.2008 (8 ♂, 2 ♀), Daniel Handfield, 21.vii.2008 (1 ♂), Norman Handfield; Roxton Falls, Québec, 24.vii.2008 (2 ♂), Norman Handfield; St-Armand, Québec, 20.vii.2004 (1 ♀), 21.vii.2004 (1 ♂), Claude Chantal, in coll. Léo-Paul Landry; Ste-Anne-de-Bellevue, Morgan Arboretum, Québec, 12.viii.2009 (2 ♂), Louis Handfield, 12.viii.2009 (1 ♂), Daniel Handfield; Varennes, Québec, 7.vii.2008 (1 ♂), Claude Chantal, in coll. Michel Pratte).

Other material examined.

USA. Specimens were examined from the following states: Arkansas (USNM), Connecticut (AMNH, USNM), Delaware (USNM), Georgia (CNC), Kentucky (USNM), Louisiana (USNM), Maryland (USNM), Mississippi (USNM), New Jersey (USNM), New York (USNM), North Carolina (USNM), Pennsylvania (USNM), Tennessee (USNM) and Virginia (USNM).

Etymology.

The Latin name sphingealis refers to the sphingid-like appearance of the males.

Diagnosis.

Herpetogramma sphingealis , like Herpetogramma aeglealis and Herpetogramma thestealis , is sexually dimorphic. The male of Herpetogramma sphingealis is likely to be confused only with Herpetogramma aeglealis , but can be distinguished from Herpetogramma aeglealis by its nearly uniform dark-brown colour and large wingspan (34-37 mm versus 29-34 mm in Herpetogramma aeglealis ). The transverse lines are obscure whereas in Herpetogramma aeglealis they are more sharply defined, usually with pale shading adjacent to them and with pale streaks between veins, especially in medial area. The hind wing is dark brown with a dark discal spot, but in Herpetogramma aeglealis the hindwing is dirty white with dark-gray shading on discal spot, wing veins, subterminal area, and an irregular but contrasting postmedial line. The female is larger than that of Herpetogramma aeglealis (31-34 mm versus 27-31 mm), has more apically-squared wings and is less uniformly dark coloured, so it resembles some females of Herpetogramma aeglealis , but females Herpetogramma aeglealis are paler, smaller, and always show a golden hue, never dark brown as in Herpetogramma sphingealis . Rare specimens of a semi-melanic form of Herpetogramma aeglealis have an overall dark coloring, as in Herpetogramma sphingealis , but the transverse lines are very well marked and followed by a larger creamy band, and also have a more extensive cream-colored shading in the costal area of the hindwing. In the male genitalia, Herpetogramma sphingealis differs from Herpetogramma aeglealis in having a longer aedeagus (10.0-10.6 × as long as the medial width compared to 8.0-8.8 × as long in Herpetogramma aeglealis ) and also in details of vesica. In the female genitalia, Herpetogramma sphingealis has a longer ductus bursa (0.27 × as long as corpus bursae in Herpetogramma sphingealis , but only 0.22 x as long in Herpetogramma aeglealis ).

Description.

Adult male:wingspan 34-37 mm ( Herpetogramma aeglealis 29-34 mm). Upperside of head, palpi (excFept tufts at base), protothoracic collar, and upperside of thorax concolourous, chocolate brown, fading to a slightly paler brown with age; antennae filiform, finely ciliate on underside, each segment concolourous dorsally with upper surface of head; upperside of abdomen concolourous with wings, except for posterior brownish-yellow tuft covering valvae; maxillary palpi, legs, and underside of head, thorax, abdomen pure white; dark-brown band (nearly width of eye on side of head) and including the top of the maxillary palpi and chaetosema gives head appearance of having a longitudinal mask; eye black with greenish bands. Forewing chocolate brown, concolourous with upperside of head, thorax, abdomen, fading slightly to a paler brown; apex acutely angled; postmedian line slightly zigzagging from costa to halfway down wing, then turning abruptly inward at nearly right angle to position below reniform spot before turning downwards and zigzagging to posterior margin of wing; no other lines visible (except sometimes a vague trace of an outward-curved antemedian line); only other marks on forewing are a white patch on fringe at anal angle, two black dots at position of orbicular and the reniform spots, a cream-coloured rectangular patch between two black dots, and a dark terminal line at base of fringe; fringe concolourous with wing except for white anal patch and slightly darker shading on veins; fringes also fading with age. Hindwing concolourous with forewing, including fringe, fringe with dirty-white shading at anal angle; no lines visible; a round (more like a lunar crescent in Herpetogramma aeglealis ) black discal dot with a creamy-white irregular patch toward wing base (nearly hidden by posterior margin of forewing). Fringes of all wings even, not crenate. Underside of all wings, including fringes, a dark grey, fading to a paler whitish grey toward wing base with white at base near pure-white thorax, especially along inner margin of hindwing; creamy patch and two black dots on forewing barely visible as is discal spot of hindwing. Legs mainly pure white, sometimes with brownish scales on upperside of anterior and posterior legs.

Adult female:wingspan 31-34 mm ( Herpetogramma aeglealis 27-31 mm). Essentially same as for male except forewing larger, less elongated, and more square at margin; colour of wings a paler chocolate brown, transverse lines more contrasting. Hindwings as for male, but colour fading near base, sometimes showing a vague trace of a postmedian line.

Genitalia. Male genitalia of Herpetogramma sphingealis differ from those of Herpetogramma aeglealis in length of aedeagus and the details of vesica. In Herpetogramma sphingealis aedeagus long, 10.0-10.6 × as long as medial width compared to 8.0-8.8 × in Herpetogramma aeglealis . Also, secondary pouch on subbasal diverticulum broad and rounded, but narrow and finger-like in Herpetogramma aeglealis . Spinules on surface of the basal part of the vesica minute and difficult to see in Herpetogramma sphingealis but larger and more conspicuous in Herpetogramma aeglealis . Female genitalia similar to those of Herpetogramma aeglealis , except for length of ductus bursae (0.27 × as long as corpus bursae in Herpetogramma sphingealis , but only 0.22 × in Herpetogramma aeglealis ), this likely reflecting longer aedeagus of Herpetogramma sphingealis . Genitalic dissections of specimens of dark semi-melanic forms allow specimens to be identified as Herpetogramma aeglealis .

Biology and habitat.

Herpetogramma sphingealis occurs in the darkest areas of rich xeric forests, with maples and oaks, especially rocky, hilly, maple groves where Christmas fern occurs commonly. Its dark-brown colour is well suited for hiding in these woods. The moth comes readily to light and flies at the beginning of the night; it is sometimes one of the first to come to light. Its flight is darting and rapid. The underside of the head, thorax and abdomen, including the legs, are pure white, so it is easily spotted when flying to the light. The moth is a beautiful cryptically-coloured creature well-adapted to hide in the darkest shadows of the woods.

According to the "Moths of Maryland" (www.marylandmoths.com) and to specimens collected by Doug Ferguson in USNM, the larvae feed on Christmas fern. Doug Ferguson collected two larvae on "Xmas Fern" at "Richard Russell Pkwy, Union County, Georgia, 25 April 1969" and reared them with success on this host plant (note by Doug Ferguson to John Glaser, in litt., sent to the author [LH] 11 August.2008).

An additional specimen was reared as a leaf roller on Christmas fern and deposited in USNM was reared by Wilton Everett Britton and emerged on the 16 July 1900. Philip Dowell (1911) noticed in 1908 in New York State that the fronds of Christmas ferns and some of woodferns ( Dryopteris Adans.) were attacked by a leaf roller, most probably by this new species for Christmas fern.

Larvae of a species of Herpetogramma were reared on Christmas fern in Athens, Georgia (Ruehlman et al. 1988); the species was identified as Herpetogramma aeglealis , but through the courtesy of Dr Matthews, one male specimen was loaned to the CNC, and a complete dissection including the vesica was prepared by Don Lafontaine, and it proved to be a specimen of the new species. All specimens for that study were determined to be a single species, due to their larvae, habits, host plant, and appearance of the adults, we believe they all belong to Herpetogramma sphingealis and not to Herpetogramma aeglealis . According to these authors, the larvae are solitary leaf rollers and live on the terminal leaflets of young fronds, passing the winter as eggs, emerging at the beginning of the spring and eating the fronds within a silk shelter for around a month, and then pupate to emerge about 12 days later.

David Wagner and his associates have reared two males and one female on Christmas fern in Connecticut. The males from Bridgewater, Litchfield Co., emerged on 12 June 1999 and 4 July1999 and a female from Chaplin, Windham Co., emerged on 30 July 2009. The specimens were identified by the author (LH).

As a result of these data, Christmas fern is the host plant of Herpetogramma sphingealis . It is possible that the larvae might be found on other species of ferns, although only one other species of the hollyfern genus ( Polystichum Roth) has a range that overlaps that of Herpetogramma sphingealis . The range of the boreal species Polystichum braunii (Spenner) Fée, Braun's holly fern, overlaps that of Herpetogramma sphingealis in Québec and New England.

In contrast to the restricted host plant records for Herpetogramma sphingealis , both Herpetogramma aeglealis and Herpetogramma thestealis appear to be more general feeders as larvae. Herpetogramma aeglealis has been reared on a variety of herbaceous plants including ragwort [ Asteraceae ] and ferns [Polypodiales] (D. Wagner, pers. comm.), goldenrod [ Asteraceae ] and raspberry [ Rosaceae ] ( Solis 2010), pokeweed ( Phytolaccaceae ) [ Forbes 1923], and mayapple [ Berberidaceae ] ( Judd 1954). Herpetogramma thestealis appears to be associated with woody plants, such as basswood [ Tiliaceae ] and hazel [ Betulaceae ] ( Forbes 1923), and Carolina silverbell [ Styraceae ] and spikenard [ Araliaceae ] (D. Wagner, pers. comm. 2011).

Distribution.

Herpetogramma sphingealis occurs from southern Québec southward in eastern United States to Georgia and Louisiana and as far west as Arkansas. Christmas fern occurs from southeastern Canada southward to northern Florida and west to eastern Iowa and eastern Texas. At present, Herpetogramma sphingealis is known to occur over most of its host plant's range, and may occur over all of it.

The species seems to be expanding its distribution, at least to the North. It is spreading to new localities in southern Québec, appearing in some places that are well collected by the authors and colleagues where it had never been seen previously. For example, Mont-Saint-Hilaire has been collected by the author (LH) since 1966, Otterburn Park (Les Bosquets Hudon) since 1970 (LH), Ste-Anne-de-Bellevue (Morgan Arboretum) since 1949 (A. C. Sheppard) and since 1971 (LH), Rougemont since 1971 (LH) and St-Armand since 1982 (LH) and Herpetogramma aeglealis has been regularly found at these localities, but Herpetogramma sphingealis appeared for the first time in 2003 and in numbers since 2004, suggesting an invading species.

We have not seen any specimens from other provinces in Canada, even from Ontario, although a search of areas where Christmas fern is common may be productive.

Remarks.

The genus Herpetogramma formerly comprised nine recognized species in North America ( Solis 2010), now increased to 10 with Herpetogramma sphingealis . The methods used in the present study may prove helpful in future systematic work on the genus.