Argyria lacteella ( Fabricius, 1794 )

Argyria lacteella ( Fabricius, 1794) View in CoL

Figs 5 View Figs 1-8 , 40 View Figs 40, 41 , 53 View Figs 51-55

Tinea lacteella Fabricius, 1794: 313 . Type locality: US Virgin Island of St Croix (see Landry et al., 2023) .

Argyria lacteella (Fabricius) View in CoL : Roque-Albelo & Landry, 2018.

Material examined: 7 ♂, 36 ♀ from Ecuador, Galápagos. – Floreana : Cerro del Asilo , GPS: elev. 366 m, S 01°18.931’, W 90°27.232’. GoogleMaps – Isabela : Volcan[o] Sierra Negra, Corason [sic] Verde , 360 m; Puerto Villamil ; 1 km W Puerto Villamil ; 3 km N Puerto Villamil ; 11 km N Puerto Villamil ; ± 15 km W Puerto Villamil; Sierra Negra [volcano], pampa zone, 1000 m ; Alcedo [volcano], NE side, camp arida alta, 200 m ; V[olcán]. Alcedo , 830 m elev .; V. Alcedo , 1100 m elev .; V. Darwin , 300 m elev[ation] . – San Cristóbal: 2 km SW P[uer]to Baquarizo [sic] ; 4 km SE Pto Baquarizo ; 1 km S El Progreso ; Chatham I[slan]d., 1000 f[ee]t .; pampa zone; base of Cerro Pelado; La Toma , ca. 5.6 km E El Progreso , GPS: 299 m elev., S 00°55.356’, W 089°31.089’. GoogleMaps – Santa Cruz: NNW Bella Vista , GPS: 225 m elev., S 00°41.293’, W 090° 19.665’ ; low agriculture zone, GPS: S 00°42.132’ W 90°19.156’; GoogleMaps Horneman Farm ; agriculture zone, near (NNW) Bella Vista , GPS: elev. 223 m, S 00°41.297’, W 090°19.670’ ; C[harles]D[arwin]R[esearch]S[tation], Barranco , 20 m elev. Deposited in CAS, CDRS, CNC, MHNG, NHMUK .

Diagnosis: In the Galápagos Islands this diminutive Crambinae ( Fig. 5 View Figs 1-8 ) with a wingspan between 11 mm for the smallest males and 14 mm for the biggest females cannot be mistaken with any other moth species. Indeed, none other harbours mostly satiny white wings with brown markings on the forewing consisting of three spots medially (one costal, one median, sometimes absent, and one dorsal), a costal triangle bisected by a thin white line subapically, and a thin stripe along the outer margin. The other mostly satiny white species in the Galápagos, i.e., Palpita galapagensis (Landry & Solis) in Landry (2016) and Palpita flegia ( Cramer, 1777) are much larger (between 26.5 and 50 mm in wingspan) and lack dark spots medially on the forewing. Other species of Argyria with similar markings are known from the continental Americas and Caribbean Islands. One of these, Argyria centrifugens Dyar, 1914 , described from Panama, is very similar, although distinctly larger, with a wingspan of 16 to 19 mm (see Landry et al., 2023). Apart from size these two species differ in the colouration of their palpi as the tip of the maxillary and labial palpi of A. lacteella are satiny white whereas the maxillary palpi of Argyria centrifugens are orange brown while its labial palpi are dark brown with the third palpomere slightly paler brown. Both species are also very different in genitalia. Based on its holotype, the male genitalia of A. centrifugens (see Landry et al., 2023, figs 21, 22) differ most notably in the three-pronged gnathos, the wider valva with a widely rounded apex and without a short hook-like projection at base but with a large membranous structure sporting a thin and pointed rod about half as long as the valva, directed toward the base of the valva and apparently articulated. Other similar species are the North American and Bermudian A. gonogramma Dyar, 1915 and the Antillean A. diplomochalis Dyar, 1913 (see Landry et al., 2023).

Biology: The moths come to light and the species can colonize habitats close to sea level as well as up to 1100 m in elevation in the Galápagos Islands. The larvae most likely feed on Poaceae as does its sister species A. gonogramma (see Landry et al., 2023).

Distribution: This is a widespread American species for which the type locality has been pinpointed to be Saint Croix Island in the United States Virgin Islands by Landry et al. (2023). It is known from southern Florida in the United States of America through the Caribbean Islands and Central and South America (see Landry et al., 2023, for a review). In the Galápagos Islands this species has been found so far only on inhabited islands ( Isabela, Floreana , San Cristóbal, and Santa Cruz), potentially indicating one or several introductions from the continent. However, on Isabela Island the species has spread onto the uninhabited slopes of Alcedo and Darwin volcanoes.