Argyrophorus argenteus argenteus Blanchard, 1852

Matz, Jess & Brower, Andrew V. Z., 2016, The South Temperate Pronophilina (Lepidoptera: Nymphalidae: Satyrinae): a phylogenetic hypothesis, redescriptions and revisionary notes, Zootaxa 4125 (1), pp. 1-108 : 17-19

Argyrophorus argenteus argenteus Blanchard, 1852

( Figs. 2 C, G–I; 3A, B; 22)

Holotype: (male) MNHN, Paris (Photo examined).

Type locality: “ Chile ” (coll. Claudio Gay, 1849)

Subspecies:

Argyrophorus argenteus elinoides Ureta, 1956

Holotype: (male) MNHN, Santiago de Chile (Photo examined) Type locality: Angol, Araucanía Province, Chile, 120 m, 17 Jan. 1952

Argyrophorus argenteus barrosi Peña, 1968

Holotype: (male) MNHN, Santiago de Chile (not examined) Type locality: South of Tongoy, Coquimbo Province, Chile

Distribution. Argyrophorus argenteus occurs amongst bunch grasses in Chile from southeastern Atacama Province to southeastern Auraucanía Province and in Argentina from northwestern Neuquén Province to western Mendoza Province from January to early March at 100–2400m above sea level ( Fig. 22 ).

Diagnosis. Easily distinguished from other species by the silver coloration on the dorsal surface of fore and hindwings ( Fig. 3 A, B). Dorsal sides of both wings of females are bordered in taupe to chocolate along the costa and the subterminal band, which is dentate at the proximal edge. Ocellus between M1-M2 on the dorsal side of the forewing is clearly visible in the females and occasionally appears as a tiny black dot in the males. Males have sparse androconia on the forewing that are obscured by the refractive nature of the silver scales, but can be viewed when backlit and a drop of 90% ETOH is applied to the junction of the veins to the discal cell. Females are more subdued in color than the males on the ventral side and bear a clearly visible postmedian band on the forewing. Male genitalia are easily distinguished by wide valvae with serrate edges visible when viewed from the ventral side ( Fig. 2 I) and an aedeagus with wing-like flanges on either side of the median ( Fig. 2 H).

Redescription. Head: Antennae 8–12mm, covered in white scales and terminating in a round club. Eyes oval and naked, length approximately 1.3 times width. In males, palp scales are white dorsally with a longitudinal black stripe along the median and white with chocolate piliform scales ventrally. Female palps white with a longitudinal bronze stripe along the median, honey piliform scales dorsally, and chocolate piliform scales ventrally. Terminal palp segment is oval and three-tenths the length of the second segment.

Thorax amber with iridescent black to bronze scales in the males and white and bronze scales in the females, both sexes with white and bronze piliform scales. Foreleg tarsi are clublike and unsegmented in both sexes. Midlegs and hindlegs with four rows of dark amber to black spines on the tibia and tarsus. In the males, the abdomen is white to cream ventrally, the dorsal side dark chocolate and bronze interspersed with white scales. Female abdomens are white ventrally and white to cream and bronze dorsally.

Forewing: Wingspan 30–34mm, females larger than the males. Termen nearly straight to slightly convex and the distal end of the discal cell sinuate with the cubital end straighter than the radial end. Males with sparse androconia in patches between R5 and CuA2. Males silver with dark chocolate and silver fringe scales and, occasionally, a small black dot between M1-M2. Females silver, taupe at the costa and with a subterminal coffeecolored band with a dentate proximal border. Fringe scales are mainly silver interspersed with sparse dark chocolate scales. Females bear a small, round or oval black ocellus between M1-M2. Ventral side silver in the males and coffee at the inner margin with a patch of rust orange over the discal cell. A thin dentate line of coffee scales is sometimes present along the terminal edge. Ocellus between M1-M2 is round, black, and unipupillate. Females are taupe on the ventral side with an orange patch over the discal cell. Postmedian band is platinum and edged in dark chocolate brown. Median border is nearly straight from the costa to M3, narrowing between M3 and CuA1 and sigmoidal in shape, widening again between CuA1-CuA2, and terminating in an acute triangle between CuA2-1A+2A. Subterminal border is dentate. Ocellus between M1-M2 is round, black, and unipupillate with a platinum ring that is circumscribed in taupe.

Hindwing: Wing oval, termen convex and barely scalloped. Dorsal side silver in the males with chocolate along the costa. Female dorsal surfaces are silver, taupe along the costa, with a subterminal border in taupe to chocolate. Proximal border of the subterminal band is scalloped. Ventral side of the males silver, bronze, and black from the base to a sinuous submedian black line. Postmedian band is silver and bordered thinly with black, irregularly sinuous at the median edge and scalloped at the subterminal edge. Ocelli are black and bordered in bronze. Ocellus between Rs-M1 is linear and 2–3mm in length. Ocellus between M1-M2 is also linear and about 10mm in length, stretching to within a few millimeters of the discal cell and the termen. Ocelli between M2 and 1A+2A are lenticular. A silver line parallel to the veins bisects the cell between CuA2-1A+2A and a narrow silver V can be seen in the discal cell, the point of the V closest to the base. Veins are highlighted in silver. Female VHW are similar, but more subdued in color, bronze appearing as taupe and silver appearing as platinum.

Male genitalia ( Fig. 2 G–I): Uncus widest at the base, narrowing gradually to a blunt finger-like terminus, and approximately 1.4 times as long as the tegumen. Gnathos acute and less than half the length of the uncus. Pedunculus long and U-shaped. Saccus U-shaped, nearly deltoid, and less than two-thirds the length of the gnathos. Valvae wide with a deltoid distal end and, when viewed from the ventral side, a serrate edge can be seen on the distal half. Aedeagus is nearly even in width from the distal end to the median, where serrate wing-like flanges appear on either side, doubling the width. From this point, aedeagus narrows to an acute proximal terminus.

Remarks. Probably the most studied of the south temperate pronophilines, no doubt due to the silver coloration on the dorsal side of both forewings and hindwings, especially in male specimens, which are unique among butterflies in their metallic silver sheen. Elwes (1903) referred to it as “one of the most beautiful and unique butterflies in Chile, or I may say in the world.” and Weymer (1911) described it as “one of the most striking insects in the American fauna.” The structural nature of this coloration has been used as a model for constructing ultra-thin synthetic broadband reflectors for use in optical devices such as lasers and solar cells ( Vukusic et al. 2009).

Elwes noted that Argyrophorus argenteus is found on grassy hillsides and both he and Weymer state that flies more slowly in the morning, but is difficult to catch in the afternoon. Henry (1992) described the immature stages and noted that the larvae fed on the bunchgrass Stipa speciosa Trinius & Ruprecht. Two subspecies other than the nominate form have been described: according to Peña (1968), A. argenteus barrosi can be found feeding on yellow flowers in coastal grassy areas of Coquimbo Province, Chile, below 50m altitude. Peña (1968) quoted O. Barros, for whom the subspecies is named, describing oviposition as slow, linear, and taking place on the ventral side of the leaves of coirón grasses ( Festuca gracillima ). Peña went on to describe the eggs as round, blunt, and pale yellow, turning silver during development. A. argenteus elinoides was described as considerably larger and found in the more southern parts of the range of A. argenteus argenteus , the females exhibiting more black markings on the dorsal surface.

Specimens examined. Chile, Bío Bío Province, (OSU) 0 0 0 0 95088, 0 0 0 0 95089, 0 0 0 0 95094, and 0 0 0 0 95107, (MTSU) CH 24-7, CH 24B-01, and CH 24B-02; Argentina, Neuquén Province, (MTSU) JMC0807 and JMC0808

Figures

FIGURE 2. Morphological characters discussed in species descriptions. A, B: Wing venation scheme for forewing (A) and hindwing (B) of Elina montrolii (OSU # 93698). Names of veins follow Comstock (1918). Abbreviations: 1 A + 2 A, 3 A = anal veins; CuA 1,2 = cubital veins; DC = discal cell; M 1 - 3 = medial veins; R 1 - 5 = radial veins; Sc = subcosta. C – F: Foreleg segmentation of male Argyrophorus argenteus (C), male Tetraphlebia leucoglene (D), male Cosmosatyrus dubii (E), and female Elina montrolii (F), showing varying degrees of segmentation and pseudosegmentation (indicated by the arrow in D). G-I: Male genitalia of Argyrophorus argenteus Blanchard, 1852 (OSU # 95107) in lateral view from the right side (G), aedeagus in lateral view from the right side (H), saccus and valvae in ventral view (I).

FIGURE 3. Composite habitus images of various monotypic genera. The left side of each specimen is the dorsal surface, the right side is the ventral surface. A, B: Argyrophorus argenteus Blanchard, 1852. male (BMNH # 789887) (A); female (BMNH # 789927) (B); C: Stuardosatyrus williamsianus (Butler, 1868) male (JMC 1003); D: Pamperis poaoeneis Heimlich, 1959 male holotype (scale bar = 1 cm; Photos provided by Ulf Buchsbaum, Zoologische Staatsammlung München); E, F: Neomaniola euripides (Weymer, 1890), showing variability of forewing shape, expanse of dorsal silver scales, and sizes and numbers of ocelli, in two specimens from Mazocruz, Puno, Peru (images from Cerdeña et al. 2014, open access).

FIGURE 22. Distribution of locality records for Argyrophorus argenteus, Pamperis poaoeneis and Stardosatyrus williamsianus.