Grapholita orbexilana Harrison

Harrison, Terry L., Gibson, Loran D. & Gilligan, Todd M., 2014, A new species of Grapholita Treitschke (Lepidoptera: Tortricidae) from the midwestern USA, Zootaxa 3755 (3), pp. 287-294 : 288-292

Grapholita orbexilana Harrison , new species

( Figs. 1–11 )

Diagnosis. The forewing ground-color scheme (basal half of wing speckled, most of apical half uniformly golden) readily differentiates G. orbexilana from any other Grapholita species occurring in the midwestern USA. In the male genitalia, the valval neck is more narrowly constricted than in any sympatric species of the genus except G. angleseana (Kearfott) , which differs in having the valva relatively broader (length to width ratio of basal section of valva 1.9 in G. angleseana , 3.0 in G. orbexilana ). In the female genitalia, a spinulose colliculum anterior to the ostium is absent in all sympatric species except G. ec l i p s an a. The following characteristics of the female genitalia of G. eclipsana differentiate it from G. orbexilana : 7th abdominal sternite widest at anterior margin, narrowing posteriorly along its entire length, posterior margin half as wide as anterior, forming a pair of rounded lobes that are separated medially by the lamella postvaginalis; open area of ostium transversely ovate (length 0.6X width), occupying medial 0.4 of sternite; located nearer anterior than posterior margin of sternite; lamella postvaginalis projecting anterad as a medial point that interrupts posterior margin of open area of ostium, the point extending anterad to 0.4 from anterior margin of sternite; lamella postvaginalis narrowing posterad to where, at 0.8 from anterior margin of sternite, it bifurcates into a pair of laterally curved acuminate projections that extend posterad to 0.9 from anterior margin of sternite; ductus bursae (including spinulose colliculum), corpus bursae, and signa similar to those of G. orbexilana .

Several far-western Nearctic species of Grapholita are similar to G. orbexilana in forewing pattern, the presence of a spinulose colliculum, and a legume-feeding larval habit (see Discussion). Each of these species, however, differs from G. orbexilana in genital morphology of one or both genders ( Heinrich 1926) and in forewing coloration (Gilligan 2012), as well as being mutually exclusive with G. orbexilana in larval host plant and geographic range.

Description. Adult ( Fig. 1 ). Head: Vestiture of brown, white-tipped scales; frons white; antenna uniformly brown dorsally, contrastingly white ventrally; labial palpus white, with some brown-tipped scales in ventral tuft of second segment. Thorax: Dorsally (including tegulae) brown with white-tipped scales, laterally and ventrally white, some scales in area between bases of prolegs tipped with light brown; forewing length 4.6–5.0 mm (n = 13), no dimorphism in size; ground color brown; scales on distal 0.25 of wing dark brown tipped with white; scales surrounding dorsal strigula unicolorous dark brown; scales on remainder of wing brown to dark brown, tipped with pale tan; fasciae indistinct from interfascial areas; costal striguale white, distinct, unpaired; striae metallic leaden gray, expressed as follows: extending from strigula 9 to nearly R5; as a small patch midway between strigula 8 and ocellus, dislocated at M1 and continuing along apical margin of ocellus; extending from strigula 7 to R4; extending from strigula 5 to corner of ocellus, dislocated at M1 and continuing along basal margin of ocellus; extending from strigula 4 to dorsal strigula; ocellus consisting of four indistinct rows of black scales extending to termen, bordered basally and apically by metallic striae arising from strigulae 5 and 8; black scales separated by rows of ground color at M2, M3, and CuA1; dorsal strigula a large white patch ca. midway between tornus and base, extending from dorsum to medial vein; tornus with dark brown white tipped scales; termen with unicolorous black scales from ocellus to below apex with distinct light patch at M1; no sexual dimorphism observed in coloration/markings; fringe pale grayish brown. Ventrally, forewing brown with multicolored iridescence, most or all of the whitish costal patches present as on dorsum; a narrow white streak immediately on either side of vein M1 from approximately 0.6 wing length to outer margin; whitish patch on hind margin at 0.5 length faintly indicated; dorsum of hindwing brown, usually with irregular patches of white scaling along anterior 0.25 width of wing; fringe with a rather broad, dark brown line at base, otherwise shining lead gray; hindwing ventrally brown, with iridescence as in forewing; extensive white scaling in anterior 0.25 width. Legs mostly white dusted with brown scales; proleg with femur, tibia, and basal 0.75 of basal tarsomere laterally brown with white-tipped scales; apical 0.25 of basal tarsomere white; second and third tarsomeres brown, ringed with white at apices; fourth and fifth tarsomeres brown; mesoleg same coloration as proleg, except femur white, and first through fourth tarsomeres brown, ringed apically with white; a pair of spurs apically on tibia, medial spur approximately 1.4X longer than the lateral; metaleg with same coloration as proleg, except femur and tibia white; two pairs of tibial spurs, at 0.5 length and at apex, the medial spur approximately 1.4X longer than the lateral in both pairs. Abdomen: Dorsally, shining gray in both genders; ventrally, white in male, white with anterior margins of most segments black in the single female specimen examined. Scent organ complex ( Fig. 6 ) of three components: (1) a pair of hair pencils; (2) a shallowly “W”-shaped intersegmental sclerite bearing an elongate lever rod laterally on either side, each rod extending to the base of one of the hair pencils; and (3) a small, crescent-shaped 8th abdominal sternite that bears a short anterolateral projection on either side. Male genitalia ( Fig. 7 ) with valva in three sections; length of basal section 0.6X total length of valva, dorsal margin straight, ventral margin convex, the section thus widening from base to reach maximum diameter (0.3X length) at midlength, then narrowing to neck; neck sharply curved ventrad, short (0.1X total valva length), narrow (width 0.75X length); cucullus broad and rounded, length 0.4X total valva length, width 0.4X length, the ventral margin densely clothed with hairlike setae; tegumen in the form of an inverted “V”; height 0.7X valva length, socii and uncus absent; base of tegumen strongly curved at base ( Fig. 8 ); gnathos absent; phallus cylindrical, length 0.7X valva length, internally containing two long fixed spines and a patch of small deciduous spines; juxta a transverse plate at base of valva, caulis length 0.3X valva length; anellus crescent shaped, cuplike. Female genitalia ( Fig. 3 ) with papillae anales large, lightly sclerotized, clothed with many short and a few long hairlike setae; apophyses well developed, anterior 1.5X as long as posterior, with a pointed, triangular development on dorsal margin of anterior apophysis at 0.2 its length from posterior end; 7th sternite clearly differentiated, extending entire length of segment; width of sternite in anterior 0.7 of its length 1.2X its length, then narrowing in posterior 0.3, width of posterior margin 0.25X length of sternite; ostium bursae large, transversely ovate, midventral, nearer to posterior than to anterior margin of sternite, extending from 0.4 to 0.8 length of sternite from its anterior margin; width of ostium 1.8X its length; lamella postvaginalis indistinct, fused with sternite, lamella antevaginalis a narrow band, separate from the sternite, at anterior margin of ostium; ductus bursae initiated by a narrow sclerotized region, its width 0.6X and length 0.25X the width of the ostium; anterad of this region, the ductus broadens abruptly into a sclerotized section, its width 0.9X and length 0.8X the width of the ostium; colliculum bearing many small spinelike projections; anterior 0.4 of ductus membranous, slightly narrower than the sclerotized region; corpus bursae membranous, its width 1.6X and length 2.4X the width of the ostium (although its dimensions may vary with mating condition and size of spermatophore(s)); two signa, at 0.5 length of corpus, each consisting of a circular, finely spinose, lightly sclerotized disc, its width 0.5X that of the ostium, with a heavily-sclerotized, thornlike projection, its length 0.25X the width of the ostium, located in the center of the circular disc.

Larva ( Figs. 2, 4 ). Length of final-instar approximately 9.0 mm (n = 5, range = 8.8–9.2 mm). Body uniform yellow, with no contrastingly colored sclerites or pinacula; body lightly sclerotized, head orangish yellow. Chaetotaxy and structure as illustrated for Grapholita , subgenus Grapholita , by Komai (1999), including unisetose SV group on eighth abdominal segment ( Fig. 4 ).

Pupa ( Fig. 5 ). Length approximately 7.0 mm (n = 2, range = 7.0– 7.1 mm). Structure as illustrated by Komai (1999) for subgenus Grapholita , except spiracles markedly larger than usual for the group as presently known.

Life history ( Figs. 9–11 ). This species is evidently monophagous on O. onobrychis . Field inspections of sympatric native legumes, including Orbexilum pedunculatum (P. Miller) Rydberg , Psoralidium tenuiflorum (Pursh) Rydberg , Lespedeza capitata Michaux , Dalea purpurea Ventenat , Amorpha canescens Pursh , and A. fruticosa Linnaeus , have not produced larvae. The moth is univoltine. The adult emerges and mates in mid-April (central Illinois), at a time when, in a typical year, O. onobrychis plants are approximately 5–10 cm in height. At this time, adults are commonly seen diurnally among populations of the host plant, and adults have been collected at dusk; they also might be nocturnal but have not appeared in UV light traps set at the host site in Illinois. Evidence of larval feeding appears in late April, when a number of leaflets at the apex of the plant are seen to be loosely tied together. This shelter eventually is enlarged into a large, conspicuous “nest” that incorporates leaflets from a number of surrounding leaves ( Fig. 10 ). At the center of the shelter, the larva cuts a leaflet transversely from midvein to margin on either side near the base of the leaflet and ties together the basal “flap” to form a pouchlike structure ( Fig. 11 ), inside of which it resides when not feeding. It forays out to feed on one or more adjacent leaves from this shelter ( Fig. 9 ). Because the shelter is at the apex of the plant, the larva usually is in intimate proximity to incipient flower tissue; however, in 24-hour no-choice feeding tests in the laboratory, larvae refused to feed on flowers and resumed feeding on leaf tissue when subsequently offered. Larval feeding continues through mid-May, with pupation occurring from late May into early June. Field observations of larval shelters in June indicate that the larva typically leaves the shelter to pupate; this is consistent with the behavior of other Grapholita species, which are known to pupate in leaf litter ( Chapman and Lienk 1971). In contrast to typical Grapholita , overwintering occurs in the pupal stage.

Pheromone attraction. On 14 April 2011, two pheromone traps were placed on the ground, approximately 20 m apart, within a known G. orbexilana host population of O. onobrychis . One trap was baited with OFM ( Grapholita molesta ) lure, the other with CM ( Cydia pomonella ) lure. Traps were deployed at 1400 hr and removed at 2050 hr Central Standard Time. No moths were in the trap baited with OFM lure, whereas 13 adult male G. orbexilana were the only insects present in the trap baited with CM lure.

Distribution. Grapholita orbexilana is recorded from central Illinois, central Kentucky, and southern Ohio, USA. Orbexilum onobrychis occurs across most of the east-central USA, including Arkansas, Iowa, Illinois, Indiana, Kentucky, Missouri, North Carolina, Ohio, South Carolina, Tennessee, Virginia, and West Virginia ( USDA, NRCS 2012). Therefore, the actual distribution of G. orbexilana may be larger than presently observed. In the interest of augmenting our knowledge of the biogeography of this moth, we encourage surveys for G. orbexilana in populations of O. onobrychis throughout the range of the plant. Minimum-impact monitoring for the presence of this moth could be easily affected by using codling moth pheromone lure for trap and release of adult male moths, and/or by scouting for the conspicuous and distinctive larval evidence.

Holotype ♂. White label, typed (slashes indicate line breaks): Collected as larva on/ Orbexilum onobrychis , USA:/Illinois, Coles County, Lincoln/Prairie Grass Trail west of/Charleston, +39° 29' 52.20", -/88° 13' 46.02", 12- V-2010, T./Harrison; emerged 22-III- /2011. Red label, typed: HOLOTYPE / Grapholita / orbexilana ♂/Harrison 2014. Deposited into the collection of the United States National Museum of Natural History ( USNM), Washington, DC, USA.

Paratypes. 1 ♀, white label, typed: [same as for holotype, except] emerged 29-III-2011. 13 ♂, white label, typed: Collected as adult in/pheromone trap baited with/codling moth lure, [same locality as for holotype], 14-IV- 2011, T./Harrison.; 1 ♂, two white labels, typed; first label: KY: Lincoln Co./near Stanford/larva coll. 23 v 2010 / leg. L. Gibson; second label: Ex larva in leaf "nest" on/new growth of/ Orbexilum onobrychis . /Emerged 8 iv 2011; 3 ♂, 3 ♀, two white labels, typed; first label: KY: Lincoln Co./near Stanford/ 14 iv 2011 /leg. L. Gibson; second label: Coll. at dusk via/sweep netting over/new shoots of/ Orbexilum onobrychis ; 1 ♂, 1 ♀, one white label, typed: OH: Adams Co./TNC’s Cedar Falls/Pres., 4.6 mi. NE/of Lynx, 2 v 2013 /leg. L. Gibson; all paratypes with blue label, typed: [same as for holotype red label, except] labeled PARATYPE, and gender of moth, where appropriate, labeled ♀.

Material examined but not designated as paratypes: 1 ♂ (wings not fully expanded), [same data as for holotype, except] emerged 25-III-2011; 1 ♀, OH: Adams Co., 1 mi. SE of Lynx, E end of Cline Rd., 2 v 2013, leg. L. Gibson; 1 ♀ OH: Adams Co., Kamama Prairie Pres. off Nixon Rd.,. 8 mi. NNE Fawcett, 2 v 2013, L. Gibson; 2 larvae, [same data as for holotype except] collected 5-V-2011, preserved 13-V-2011; 1 pupa, [same data as for holotype except] collected 5-V-2012, preserved 23-V-2012. Specimens deposited in USNM; collection of James R. Wiker, Greenview, Illinois, USA; and collection of Loran. D. Gibson, Florence, Kentucky, USA.

Etymology. The moth is named for Orbexilum Rafinesque , the genus of the larval host plant.

Figures

FIGURES 1 – 11. Morphology and life history of Grapholita orbexilana. 1. Adult. 2. Final-instar larva. 3. Female genitalia. 4. Larval cuticle, eighth abdominal segment, left-lateral aspect, showing a single SV seta; SP, spiracle. 5. Pupa, ventral, leftlateral, and dorsal aspects. 6. Adult male postgenital structures. S 8 (inset, at same scale as rest of photo), crescent-shaped eighth abdominal sternite, bearing a pair of short anterolateral projections; in situ, S 8 is in intimate contact with the medial part of the intersegmental sclerite; ISS, intersegmental sclerite with medial shallowly “ W ” - shaped part and lateral elongate lever rods connected to bases of hair pencils; HP, hair pencil. 7. Male genitalia, caudal aspect, spread. 8. Male genitalia, left-lateral aspect (left valva removed and aedeagus reflected dorsad) showing strongly curved base of tegumen (at arrow). 9. Feeding damage caused by one larva. 10. “ Nest ” of one larva. 11. Larval shelter at base of leaflet.