Macrosaccus neomexicanus Davis

Davis, Donald R. & De Prins, Jurate, 2011, Systematics and biology of the new genus Macrosaccus with descriptions of two new species (Lepidoptera, Gracillariidae), ZooKeys 98, pp. 29-82 : 51-53

Macrosaccus neomexicanus Davis sp. n. Figs 1623 –2745– 50Tables 12

Diagnosis.

As discussed in the diagnosis of Macrosaccus robiniella , this species most resembles the former in general appearance. They differ in distribution, host preference, in genital morphology (see diagnoses of Macrosaccus robiniella ), and possibly overall size, with the wingspan of neomexicanus being slightly larger.

Adult

(Fig. 6). Forewing length 2.7-3.5 mm.

Head: Vestiture of head and antenna similar to Macrosaccus robiniella ; apical segment of antenna white to grey.

Thorax: Dark brown dorsally, with whitish suffusion anteriorly and laterally; white ventrally; tegula dark brown, with pale grey to white suffusion anteriorly. Forewing and hindwing patterns very similar to Macrosaccus robiniella . Vestiture of legs similar to Macrosaccus robiniella .

Abdomen: Similar to Macrosaccus robiniella , dark fuscous dorsally and white ventrally with greyish suffusion on anterior portion of segments 2-7 laterally and sometimes ventrally on A8.

Male genitalia (Figs 23, 24): Valva relatively simple, gradually narrowing before apex without abrupt constriction; apex narrowly rounded, densely setose, particularly along costal margin. Saccus a slender, elongate rod ~ 1.3 × length of valva. Aedeagus very long and uniformly slender, ~ 2.5 × length of valva.

Female genitalia (Figs 25-27): Ductus bursae moderately long and slender, ~ 1/3 the length of elongate corpus bursae. Accessory bursae nearly as long as corpus bursae, arising from junction of ductus bursae and corpus bursae; with a smaller lateral pouch arising ~ midway along side of accessory bursae. Corpus bursae relatively slender, anterior end only slightly broader; a dense scattering of minute spicules encircling middle; remaining walls of corpus bursae entirely membranous.

Larva and pupa.

Similar to that of Macrosaccus robiniella .

Larval mine

(Figs 46-50). The mine begins as a relatively short, serpentine track which enlarges to an elongate-oval, whitish blotch located on the under (abaxial) side of the leaflet. As the larva develops and begins laying down silk, the mine becomes strongly tentiform, causing the upper (adaxial) surface to roll over (Figs 48, 49).

Host.

(Table 1). Fabaceae : Robinia neomexicana Gray. The host is a moderately small, spiny shrub growing to as high as 5 meters and usually forming dense thickets (Fig. 45). It occurs from California to Texas and north to Wyoming.

Life history

(Figs 46-50). Some collections of this species from southern Arizona have been from dense infestations. In such populations, oviposition tends to be concentrated on fewer available leaflets with as many as 45 short, initial serpentine mines observed on a single leaflet. These soon coalesce resulting in a single large blotch covering nearly the entire lower side of the leaflet (Fig. 47). Larval mortality is probably high under these conditions. One large composite mine opened contained 14 live and 11 dead, late instar larvae and no pupae. A maximum of 11 cocoons with pupae (5 on one side of the midrib and 6 on the other side) were found in one leaflet (DRD rearing lots 541, 541.1, Fig. 50).

Holotype.

♂: UNITED STATES: ARIZONA: Cochise Co: Carr Canyon: Huachuca Mts: 20 Sep 1985, em. 27 Sep 1985, HOST: Robinia neomexicana , R. S. Wielgus, digital image captured, (USNM).

Paratypes.

UNITED STATES: ARIZONA: Coconino Co: North Rim Grand Canyon: 1 ♀, 15-16 Aug 1978, em. 17 Aug - 6 Sep 1978, G. Deschka, HOST: Robinia neomexicana , (BMNH). Cochise Co: Carr Canyon: Huachuca Mts: 70 ♂, 57 ♀, 20 Sep 1985, em. 21 Sep - 2 Oct 1985, R.S.Wielgus, DRD541, HOST: Robinia neomexicana , slides USNM 28416, 30890, 34267, (USNM). NEW MEXICO: Catron Co: Rocky Canyon., Gila Nat. Forest: 1 ♂, 1969, em. 6 Aug 1969, D. & M. Davis, DRD642.2, Host: Robinia neomexicana , (USNM). Otero Co: Deerhead Campground, ca. 2 mi. S. Cloudcroft: 1 ♂, 1 ♀, 18-19 Jul 1969, em. 2 Aug 1969, D. & M. Davis, DRD 642, Host: Robinia neomexicana , DNA/BOLD ID RDOPO084-09, GenBank GU669596, DNA/BOLD ID RDOPO085-09, GenBank GU669597, (CCDB, USNM). Sandoval Co: Pakitza Campground, 4 mi. E. Ponderosa, Santa. Fe Nat. Forest: 7 ♂, 9 ♀, em. 4-11 Aug 1969, D. & M. Davis, DRD 642.1,Host: Robinia neomexicana , slides USNM 34183, 34184, (USNM).

Distribution.

Known only from the southwestern United States from Arizona and New Mexico.

Etymology.

The specific name is derived from the specific name of its plant host. The specific epithet is an adjective in the nominative singular.