The wing pattern ofMoerarchisDurrant, 1914 (Lepidoptera: Tineidae) clarifies transitions between predictive models

Abstract

The evolution of wing pattern in Lepidoptera is a popular area of inquiry but few studies have examined microlepidoptera, with fewer still focusing on intraspecific variation. The tineid genus Moerarchis Durrant, 1914 includes two species with high intraspecific variation of wing pattern. A subset of the specimens examined here provide, to my knowledge, the first examples of wing patterns that follow both the ‘alternating wing-margin’ and ‘uniform wing-margin’ models in different regions along the costa. These models can also be evaluated along the dorsum of Moerarchis, where a similar transition between the two models can be seen. Fusion of veins is shown not to effect wing pattern, in agreement with previous inferences that the plesiomorphic location of wing veins constrains the development of colour pattern. The significant correlation between wing length and number of wing pattern elements in Moerarchis australasiella shows that wing size can act as a major determinant of wing pattern complexity. Lastly, some M. australasiella specimens have wing patterns that conform entirely to the ‘uniform wing-margin’ model and contain more than six bands, providing new empirical insight into the century-old question of how wing venation constrains wing patterns with seven or more bands.

The wing pattern of Hydriomena Hübner, [1825] (Lepidoptera: Geometridae: Larentiinae) lacks a predictable relationship with venation

“…Rs 4 terminates along the termen on the wings of Hydriomena , and this is believed to be the ancestral state for Lepidoptera (Schachat & Gibbs, ). However, Rs 4 terminates along the costa in two of the groups of Microlepidoptera that were previously examined (Schachat, ; Schachat & Brown, ), and in those groups the relationship between Rs 4 and wing pattern occurs as predicted by the wing‐margin models. Therefore, Rs 4 is discussed here in conjunction with the veins that terminate along the costa.…”

“…In Micropterix Hübner, 1825 and in species of Sabatinca Walker, 1863 that occur in New Zealand, the majority of specimens examined have wing patterns that conform to the alternating wing‐margin model, with violations of this model attributable to confluence or lack of expression (Schachat & Brown, , ). The uniform wing‐margin model typically holds for the tineid genus Moerarchis Durrant, 1914, and violations of this model can be attributed to transitions to the alternating wing‐margin model (Schachat, ). The uniform wing‐margin model also predicts the relationship between wing pattern and venation in various psychid genera from Australia and for the xyloryctid genus Lichenaula Meyrick, 1890.…”

“…In groups that conform to the alternating wing‐margin model, the implications of this model for the termen and for the posterior margin are obscured by the confluence of pattern elements (Schachat & Brown, , ) and by the lack of expression of plesiomorphic veins (Schachat & Gibbs, ). In microlepidopteran groups that conform to the uniform wing‐margin model, one spot tends to surround each vein along the termen and along the posterior margin, with the consistent exception of CuP (Schachat, ) and the occasional exception of A (Schachat, ). Acronictinae also conform to the uniform wing‐margin model, but along the termen in this group, dark spots occur between veins instead of on them (Schachat & Goldstein, ).…”

“…The alternating wing‐margin model was first described in Tortricidae (Baixeras, ; Brown & Powell, ), has been found to hold for the most early‐diverging extant moths with wing patterns (Schachat & Brown, , ), and has been used to identify homologies between butterfly wing patterns and the plesiomorphic wing pattern for crown Lepidoptera (Schachat & Brown, ). The uniform wing‐margin model has been found to hold for most of the microlepidopteran genera examined thus far (Schachat, , ; Schachat & Brown, ) and also for the noctuid subfamily Acronictinae (Schachat & Goldstein, ), which is far more closely related to Geometridae than butterflies are (Heikkilä et al, ; Regier et al, ).…”

“…In recent years, the relationship between wing pattern and venation has been used to identify potentially homologous pattern elements, primarily in Microlepidoptera (Baixeras, ; Brown & Powell, ; Schachat, , ; Schachat & Brown, , , ). The predictive power of the relationship between wing pattern and venation was confirmed when the wing pattern of mandibulate moths was successfully used to predict the precise location of a plesiomorphic wing vein for Lepidoptera (Schachat & Brown, , ; Schachat & Gibbs, ).…”