Libytheana florissanti ( Scudder, 1892 )

Kawahara, Akito Y., 2013, <strong> Systematic revision and review of the extant and fossil snout butterflies (Lepidoptera: Nymphalidae: Libytheinae) </ strong>, Zootaxa 3631 (1), pp. 1-74 : 54-55

Libytheana florissanti ( Scudder, 1892)

( Fig. 62 )

Barbarothea florissanti Scudder 1892: 23 , pl. 3, Figs. 1–5 . Shields 1985a: 13 [= Libythea ].

Oligodonta florissantensis Brown 1976: 1 [new synonymy].

Libythea florissanti Shields 1985a: 13 .

Preservation. Libytheana florissanti is a fossil preserved with the right ventral side exposed. Both antennae are preserved, one perfectly. It is difficult to determine where the antennae arise on the head. The complete antenna has 44 segments, with a terminal club of 11 or 12 segments. The specimen can be recognized as a nymphalid by the three distinct carinae on the right antenna, a synapomorphy for Nymphalidae ( Kristensen 1976, Ackery et al. 1998). The labial palpus is three times as long as wide. All three segments have hairs, but the length of the hairs shortens apically ( Scudder 1892). Only two legs are visible, one of which is perfectly preserved. Based on their length and simplicity, Scudder (1892) believed they might be the prothoracic pair. He noted that the posterior surfaces of the tarsi are covered in spines, which suggests that this specimen is a female. Wing venation and pattern are partially visible, but greatly obscured by the irregular surface of the sediment. Visible wing venation is consistent with the venation of modern Libytheinae . Scudder noted that the underside of the hindwing is darker than the forewing, another feature common to extant Libytheinae .

The specimen originally described as Oligodonta florissantensis Brown was found in the same Florissant bedrock of Colorado that contained the other two Libytheinae fossils. The specimen was fossilized with its wings closed, exposing the left side. The general resemblance is remarkably similar to Libythea florissanti , the only major difference being that it is preserved facing the opposite direction, and lacking labial palpi.

In a description of Oligodonta florissantensis, Brown (1976: 2) stated, ‘The costal margin is about 26.5 mm long. R 4 + R 5 [= Rs 3 + Rs 4] branches 5.1 mm from the apex, M1 does so 8.4 mm from the apex. R2 and R1 [= Rs 1 and Rs] originate close together, 12.8 and 15.7 mm respectively from the apex with R2 [= Rs 1] rising just basad of the origin of [the discal cell]... The drawing of M2 and M3 [= M 2 and M 3] is a little erroneous... The size of the insect I believe eliminates Lycaenidae , Riodinidae and Libytheidae .’ Brown eliminated the fossil as a possible snout butterfly because of the length of the forewing costa. However, many Libytheinae have costal lengths that are approximately 26 mm, indicating that the specimen cannot be ruled out as a snout butterfly.

Biology. Unknown.

Deposition. Scudder’s specimen was collected by S. H. Long, but is presumed lost ( Shields 1985a). Brown’s specimen was excavated from the Singer Trench in the late Oligocene volcanic lake shale of Florissant, Teller County, Colorado ( Brown 1976). The specimen described by Brown (1976) is separated into two sides. The side exposing the right ventral surface is stored in the Florissant Fossil Beds National Monument (FFNM), and the other half is located in the Florida Museum of Natural History, Invertebrate Paleontology Division (FLMNH).

Remarks. Scudder felt his specimen was intermediate between Libythea and Prolibythea , because of its large wing size and antennal characteristics. He therefore erected Barbarothea Scudder , but was unable to compare this fossil with the known extant species of Libytheinae at the time. Shields (1985a) synonymized Barbarothea with Libythea because of its close resemblance with one of the species that Scudder did not study, namely, Libythea geoffroyi . Shields (1985a) noted the close similarity in the labial palpus, facial hair, hindwing crenulations, antenna shape, and terminal projection of the forewing apex. Kawahara (2009) scored this fossil and included it in a cladistic analysis of Libytheinae . The fossil of florissanti clearly has a forewing Rs 2 vein that arises intermediately between fork Rs 3 + Rs 4 and the discal cell apex, a feature that is absent in all species of Libythea , and thus florissanti was transferred to Libytheana .

Brown (1976) described Oligodonta florissantensis and placed this species in the Pieridae , because he believed the wing venation resembled that of extant pierids. However, his illustration of the wing venation is flawed, and closely resembles the Libytheinae . For example, wing veins of the fossil are not as straight as illustrated — as Brown stated, ‘The drawing of the M 2 and M 3 [veins] is a little erroneous’ ( Brown 1976: 3). Furthermore, Brown failed to accurately illustrate the apex of the forewing, which, on the actual specimen is much more prominent than in Brown’s illustration and resembles the apex of extant Libytheinae . I treat Oligodonta florissantensis Brown as a junior synonym of Libytheana florissanti (Scudder) because of its close resemblance in wing venation and shape to the latter, and because both were collected in the Oligocene Florissant beds of Colorado. For additional illustrations and images, refer to Scudder (1892) and Shields (1985a).

Figures

FIGURE 1. Phylogeny of snout butterflies based on morphology (after Kawahara 2009). Numbers above and below each rectangle refer to the characters and states in Kawahara (2009). A dark rectangle indicates a unique character state change (synapomorphy), a white rectangle indicates homoplasy. Large numbers indicate branch support (Bremer Support/jackknife). Due to limited space, outgroups are not shown in this figure.

FIGURES 2−13. Lateral view of the male eighth abdominal tergum of Libythea and Libytheana with scales and hairs removed. 2. Libythea celtis; 3. Libythea collenettei; 4. Libythea geoffroyi; 5. Libythea labdaca; 6. Libythea laius; 7. Libythea lepita; 8. Libythea myrrha; 9. Libythea narina; 10. Libytheana carinenta; 11. Libytheana fulvescens; 12. Libytheana motya; 13. Libytheana terena.

FIGURES 54−62. Wing venation of Libythea and Libytheana. Fine lines indicate margins of wing markings; 54. Libythea cinyras; 55. Libythea collenettei; 56. Libythea geoffroyi; 57. Libythea labdaca; 58. Libythea laius; 59. Libythea lepita; 58. Libythea myrrha; 60. Libythea narina; 61. Libytheana florissanti.