Macrosaccus coursetiae, Eiseman & Davis, 2017

Eiseman, Charles S. & Davis, Donald R., 2017, A new species of Macrosaccus (Lepidoptera: Gracillariidae: Lithocolletinae) from Arizona, USA, Zootaxa 4358 (2), pp. 385-392 : 385-391

Macrosaccus coursetiae , sp. nov.

Figs. 1–7

Adult ( Figs. 1, 2 ). Forewing length 2.5–3.0 mm. Head: Frons white, smoothly scaled. Vertex rough, with scattered, erect, brownish piliform scales intermixed with white piliform scales; occipital area also rough, covered with mostly white, piliform scales. Labial palpus mostly black dorsally and laterally, white ventrally, and brown toward base. Antennal segments dusky with pale bases.

Thorax: Gray-brown above; white with black markings below. Forewing with ground of dusky-tipped white scales; patches of pure white scales forming more or less distinct oblique dorsal and costal streaks and an apical spot; dusky-tipped orange-brown scales forming several patches, mostly in the costal half; a basal streak of mostly pure orange-brown scales near the costal margin, these being the only orange-brown scales in the basal quarter of the wing; several small patches of black or black-tipped scales, these absent from the dorsal margin; fringe pale brown with a black subapical band. Hindwing (including fringe) gray-brown. Legs banded black and white, with patches of brown scales.

Abdomen: Grayish brown dorsally, with dark brown spots laterally (~ one per segment); venter mostly white, with midventer pale brown.

Male genitalia ( Figs. 3A–B ): Valva relatively simple, of uniform width and slightly curved throughout its length; apex truncate, with ventral margin of cucullus moderately produced and subacute; saccus a slender, elongate rod ~ 1.7× the length of valva. Phallus long (~ 3× the length of valva) and slender, with basal end slightly swollen and 2 minute spines present near apex.

Female genitalia ( Figs. 4A–B ): Ostium broadly truncate. Ductus bursae broadest near caudal end, gradually narrowing anteriorly, and approximately equal in length to corpus bursae. Corpus bursae moderately broad and elliptical in shape, with 8–10 longitudinal rows of minute, acute spicules concentrated over anterior half of corpus; a relatively small accessory bursa arising from anterior third of ductus bursae and joined by an elongate, slender duct.

Leaf mine ( Figs. 5–7 ). The larva forms a white blotch on the lower leaflet surface. Based on the two aborted mines examined, which measure 1 mm and 3 mm across, there is not an initial linear track as is sometimes present in gracillariid blotch mines. Ultimately the blotch occupies most of the lower leaflet surface and becomes tentiform, with numerous fine longitudinal folds, causing the lateral leaflet margins to curl downward. The upper leaflet surface becomes finely speckled with white as the larva consumes minute patches of palisade parenchyma. Upon emergence of the adult, the pupa is thrust through the lower epidermis at the base of the leaflet.

Type material. Holotype: ♂, UNITED STATES: Arizona: Pima Co.: Tucson , 10 Nov. 2012, em. 18 Nov. – 5 Dec. 2012, C. S. Eiseman & J. A. Blyth, ex Coursetia glandulosa , #CSE148, digital image captured ( USNM 00913184 ) .

Paratypes: Same collection data as holotype: 9♂, slides USNM 34623♂, 34759♂; 7♀, slide 34760♀; wing venation slide USNM 34774♀, (USNM).

Distribution. The entire type series was collected from a single shrub growing in a wash on the west side of Tucson, Arizona, USA.

Etymology. The specific name is derived from the generic name of the host plant, Coursetia DC. The speciesgroup name of the moth is a latinized noun in genitive singular, gender feminine. It is combined with the generic name Macrosaccus of which the gender is masculine. Since the species-group name coursetiae is a noun in apposition its ending does not need to agree in gender with the generic name with which it is combined and must not be changed to agree in gender with the generic name (ICZN Art. 34.2.1).

Diagnosis. The speckled appearance of the forewings, produced by the dark-tipped white scales, is unique among the known species of Macrosaccus . All other species have a ground color of solid pale orange-brown, and possess more well-defined costal (and often dorsal) strigulae. The male genitalia of M. coursetiae differ from those of all other Macrosaccus in possessing a truncate cucullus, with the distal-ventral margin of the cucullus subacute and not rounded. The wing venation of M. coursetiae agrees with that of M. robiniella (Davis & De Prins 2011) in all respects including the presence of 8 veins in the forewing and 5 veins in the hindwing. The general morphology of the female bursa, particularly the signa, associates M. coursetiae most closely with M. morrisella (Fitch) .

......continued on the next page Host Plant ( Figs. 7–9 ). Adults were reared from Coursetia glandulosa A. Gray (Fabaceae) , the distribution of which is limited to southern Arizona in the USA, continuing through western and southern Mexico to Oaxaca. The genus Coursetia also occurs from the southern tip of Texas south to northern Argentina ( Lavin 1988) . Although no flowers or fruit were present at the time of collection, the leaf shape, stipules, and twig color and shape were sufficient to distinguish the host plant from similar fabaceous shrubs found in the same habitat and locality (L. Crumbacher, in litt.).

Parasitoids. A single adult of Chrysocharis walleyi Yoshimoto (Eulophidae) was reared along with the type series of Macrosaccus coursetiae .

Figures

FIGURES 1–2. Macrosaccus coursetiae adults. 1, LiVe specimen in resting pOsitiOn.2, HOlOtype male.

FIGURES 3–6. Macrosaccus coursetiae. 3, Male genitalia: A, Phallus; B, Genital capsule. 4, Female genitalia: A, Lateral VieW;B, Ventral VieW.5. LarVal minein leafletOf Coursetia glandulosa. 6,AbandOned leaf mineWith pupal exuViae prOtruding frOm base Of leaflet.

FIGURES 7–9. Coursetia glandulosa. 7, Basal pOrtiOn Of leaf With tWO mines Of Macrosaccus coursetiae (abaxial surface). 8, WhOle leaf (adaxial surface). 9, Detail Of stipules and tWig.