Grapholita thermopsidis Eiseman & Austin, 2020

Eiseman, Charles S., Austin, Kyhl A., Blyth, Julia A. & Feldman, Tracy S., 2020, New records of leaf-mining Tortricidae (Lepidoptera) in North America, with the description of a new species of Grapholita, Zootaxa 4748 (3), pp. 514-530 : 519-525

Grapholita thermopsidis Eiseman & Austin , spec. nov.

( Figs. 18–41 )

Holotype. ♂, USA: Colorado: Chaffee Co.: Nathrop, Mesa Antero (38.673161, -106.127711), 5.vii.2015, em. 29.iii.2016, C.S. Eiseman & J.A. Blyth, ex Thermopsis , # CSE2293 ( CUIC). Affixed with the following red handwritten label: “ HOLOTYPE Grapholita thermopsidis Eiseman & Austin ”.

Paratypes. 4♀♀, same data as holotype except 1♀ em. 7.iv.2016 (# CSE2337 , CUIC) and 1♀ with larva col- lected 7.vii.2015, em. 5.iv.2016 (# CSE2322 , USNM). All paratypes affixed with the following yellow handwritten label: “ PARATYPE Grapholita thermopsidis Eiseman & Austin ” .

Additional material examined. 2 larvae (one cut and cleaned to make pelt), same collection data as holotype, preserved 22.vii.2015 (# CSE1754 , CUIC) .

Diagnosis. Grapholita thermopsidis can be separated from all other Nearctic Grapholitini by the following combination of forewing characters: dorsal strigula white and undivided; ocellus bordered laterally by iridescent pale purple scales and containing four faint longitudinal black lines; and costal strigulae becoming iridescent bluepurple along longitudinal axis. The genitalia are consistent with members of the Nearctic jungiella -group (see Harrison et al. 2014). The shape of the sterigma separates it from all Nearctic Grapholita except G. eclipsana (Zeller) . From G. eclipsana it differs in having a broader band-like lamella antevaginalis. Distinguishing male genitalia of this group relies heavily on the size, shape, number, and placement of cornuti, which we were unfortunately unable to carefully examine in this new species as the phallus was lost prior to examination by KAA and the initial photograph of it from 2017 is very blurry. Grapholita thermopsidis is the only described species of Grapholita known to feed on Thermopsis (but see Comments below).

Adult description ( Figs. 18–21 , 40–41 ). Forewing length 4.0– 4.6 mm (mean = 4.3; n = 5).

Head: Scales on vertex ashy silver; scales on frons white. Labial palpus white, second segment with scales expanding loosely on ventral face, third segment with a few ashy silver scales. Scape and antenna with dorsal half ashy silver, ventral half white. Chaetosemata 0.5–0.75× length of scales on vertex; ocellus moderate in size, only narrowly separated from compound eye.

Thorax: Tegulae and dorsum of metathorax concolorous with vertex; dorsum of prothorax and mesothorax dark brown. Lateral and ventral portions of thorax white with intermixed glossy dark gray scales. Forelegs with lateral face glossy dark gray, median face white to pale gray; tarsomeres dark gray with apices ringed in white. Midlegs similar to forelegs but with lateral face of femur and tibia pale silver. Hindlegs also similar to forelegs but with lateral face of femur and tibia pale gray to dirty white. Forewing ground color ashy silver to or nearly to costal strigula 4, iridescent dark brown to black beyond; dorsal strigulae united to form a solid white patch; strigulae white, well developed except for strigulae 6 and 7, which are short and often united; iridescent blue-purple striae emanating from strigula 4 towards dorsal strigulae, from strigula 5 towards basal transverse band of ocellus, from strigula 8 towards distal transverse band of ocellus, and from strigula 9 towards subapical whitish stria; ocellus bordered laterally by iridescent pale purple scales and containing four faint black longitudinal lines on a faint orange central field; basal line black; fringe glossy silver. Depending on angle of lighting, the iridescent blue-purple forewing scales may not be visible (compare Fig. 18 to Fig. 19 ). Dorsal surface of hindwing dark brown; costa white to 0.67×; fringe dark brown. Ventral surface of wings with brilliant multicolored iridescent scaling; strigulae present along forewing costa. No sexual dimorphism observed.

Abdomen: Vestiture of abdomen with dorsum glossy lead gray, ventral surface concolorous but with wide row of white scales on apical portion of segments. Remnants of hair pencil (“coremata” sensu Komai) between A8 and A9 appear to be present, but abdominal pelt of sole male specimen badly mangled making confirmation difficult.

Male genitalia ( Fig. 20 ) with uncus, socii, and gnathos absent; tegumen broad, weakly-sclerotized, curved at base (demarcated with arrow in Fig. 20 ), 0.5× length of valva; valva composed of three sections: (1) a basal third with straight dorsal margin, evenly curved on ventral margin, composed of basal cavity and sacculus, (2) a constricted and ventrally-curved neck, and (3) broadly-rounded cucullus covered in fine setae on ventromedial surface. Basal cavity 0.3× length of valva; sacculus 0.3× width of basal third of valva; at widest point basal third 0.3× length of valva; at narrowest point neck width 0.1× length of valva; length of cucullus 0.45× length of valva; at widest point cucullus 0.3× length of valva; juxta with T-shaped sclerotization, shallowly notched dorsally; phallus lost prior to examination by KAA, but present (albeit blurry and badly mangled) in initial photograph of genitalia from 2017: phallus ( Fig. 20B ) cylindrical, length approximately 4× width, no fixed spines or cornuti observed.

Female genitalia ( Fig. 21 ) with papillae anales unusually broad for the genus, densely roughened and covered with setae on ventral surface; apophyses posteriores and anteriores straight, approximately equal in length; apophyses anteriores with a small triangular projection at approximately 0.25× length; sterigma large, well sclerotized, broadest at midpoint, with V-shaped notch posteriorly; lamella postvaginalis with short extension into ostium and longer extension posteriorly, covered in fine, short setae throughout; lamella antevaginalis well sclerotized, bandlike; ostium wide; colliculum well sclerotized; base of ductus bursae heavily sclerotized, with dense patches of short spines; base of corpus bursae of similar width to anterior portion of ductus bursae, making the distinction between them ambiguous; ductus seminalis and bulla seminalis short, broad, pouch-like; width of unmated corpus bursae 0.5× length; two short, thorn-like signa present at 0.5× length of corpus bursae: one on dorsal face and one on ventral face, each with a small disc of fine inward-pointing thorns at base.

Larva ( Figs. 22–24 ). Length of one preserved larva approximately 5.6 mm. Length of one photographed, non-preserved larva approximately 7.0 mm. Body uniformly pale yellow; pinacula concolorous; prothoracic shield glossy yellow. Head capsule pale orange-yellow with black pigmentation surrounding stemmata and lateral head apodeme; chaetotaxy typical for subgenus Grapholita as described by Komai (1999), including SV group unisetose on A8 ( Fig. 23 ); anal fork present.

Pupa ( Figs. 25–29 ). Length 4.2–4.8 mm (mean = 4.5; n = 5); structure typical for subgenus Grapholita as described by Komai (1999).

Etymology. The specific epithet refers to the genus of the larval host plant, Thermopsis R.Br. The name of this new species is formed taking the genus name of the larval host plant as a noun in the nominative case. This combination of species-group name agrees with Art. 31.2.1. of the ICZN.

Host. Fabaceae : Thermopsis rhombifolia (Pursh) Richardson ( Fig. 30 ).

Biology. Leaf-mining larvae were collected on 5 and 7 July. Typical mines resemble the “underside tentiform” mines of lithocolletine gracillariids, formed along one side of the leaflet midrib and causing the leaflet to buckle ( Figs. 31–35 ). The loosened lower epidermis is pale brown and finely wrinkled, with a hole at one end from which the frass is expelled. The upper epidermis is green in younger mines, becoming mottled with whitish or brown as the parenchyma is consumed. Some mines are formed on the upper surface (CSE2322), and these cross the midrib in both photographed examples ( Figs. 36–37 ). By 15 July, captive larvae were beginning to exit their mines and spin extensive webbing on one leaf surface, causing the leaflet to curl or fold ( Figs. 38–39 ). Feeding continued within the resulting shelter. Fresh leaves were added to the rearing vials as the original ones deteriorated, and the larvae formed new shelters by tying these leaves together. Pupation took place between the tied leaves in early August. Adults emerged the following spring, 4–5 weeks after being removed from refrigeration ( Figs. 40–41 ). Given that this would have occurred much later under natural conditions, it is likely that this species is univoltine.

Parasitoids. Four adults of Zagrammosoma mirum Girault ( Hymenoptera : Eulophidae ) emerged on 21 and 22 July 2015 from both upper and lower surface mines collected on 7 July (CSE1769, UCR). Two adults of an undetermined species of Dolichogenidea Viereck ( Hymenoptera : Braconidae ) emerged on 21 and 25 July from lower surface mines, and a third was found dead on 5 August (CSE1778, CNC).

Comments. Following Komai (1999), Grapholita thermopsidis belongs to the jungiella -group of subgenus Grapholita based on larval host preference ( Fabaceae ), forewing pattern and coloration, and the female colliculum possessing a “sclerotized ring bearing minute thorns”. However, we did not observe the small “darkly pigmented sclerite situated anterodorsal to ventral prolegs on A2–A6” apparently present in larvae of Palearctic members of the jungiella -group. The dissection of the only known male of G. thermopsidis was performed prior to KAA examining the specimen and unfortunately the phallus was lost shortly after. Harrison et al. (2014) listed Nearctic members of the jungiella -group. In addition to G. thermopsidis , we also propose including G. boulderana McDunnough in this group based on identical forewing pattern to that of G. orbexilana Harrison , its possible sister species in the east.

To our knowledge this is the first record of leafmining in Grapholita . Two other North American grapholitines are known to mine leaves, in addition to Talponia plummeriana (discussed below): Dichrorampha incanana (Clemens) feeds on Arnoglossum Raf. and Packera Á.Löve & D.Löve ( Asteraceae : Senecioneae) and is a leafminer throughout its development ( Priest 2008; Eiseman 2014a); Ricula maculana (Fernald) feeds on Schoepfia schreberi J.F.Gmel. (Schoepfiaceae) and has similar habits to G. thermopsidis— first forming leaf mines from which the frass is expelled, later feeding within tied or folded leaves ( Dyar 1901).

Brown et al. (2008) list Grapholita “ thermopsae ” as feeding on Thermopsis macrophylla Hook. & Arn. in California, citing Powell (2006). BSCIT (2019) lists a specimen of “ Grapholita thermopsae Powell & Sm. ms” at EME collected by J. Powell on 28 February 1967 at Carson Ridge, Marin Co., California. J. Powell (in litt. to CSE, 31 March 2016) informed us that this manuscript name for an undescribed species was from an aborted collaboration with Norm Smith, then an M.S. student at UC Davis. He did not provide details of the larval biology but doubted that the California species was conspecific with our new species from Colorado. We were unable to examine the EME specimens for this study, as J. Powell (in litt. to KAA, 9 November 2019) was unable to locate any.

Figures

FIGURES 18–19. Grapholita thermopsidis. 18: Holotype male; 19: Paratype female.

FIGURES 20–23. Grapholita thermopsidis. 20: Male genitalia (arrow indicates curved base of tegumen; 20B = phallus, not to scale); 21: Female genitalia; 22: Larva; 23: Detail of larval pelt (A8).

FIGURES 24–29. Grapholita thermopsidis. 24: Live larva; 25: Live pupa, lateral view; 26: Same, ventral view; 27: Pupal exuviae, dorsal view; 28: Same, ventral view; 29: Same, lateral view.

FIGURES 30–41. Grapholita thermopsidis. 30: The host plant, Thermopsis rhombifolia; 31: Leaf with mine (right of center); 32: Detail of same mine; 33: Lower-surface view of same mine; 34: Upper surface of a different mine; 35: Same, lower surface; 36: An upper-surface mine, centered on the leaflet midrib; 37: Another upper-surface mine, crossing midrib at lower left; 38: Older larva spinning silk to form leaf shelter; 39: A completed folded-leaf shelter; 40: Reared adult, dorsal view; 41: Same, lateral view.