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

Abstract

Two simple models have been successfully applied to predict the relationship between wing pattern and venation in various lineages of Lepidoptera. However, neither of these models holds for the geometrid genus Hydriomena Hübner, 1825. Wing patterns in Hydriomena were studied intensively during the 1920s after the description of the nymphalid groundplan, an idealized schematic that outlines the primary elements of butterfly wing patterns; geometrids strongly resemble butterflies and, until recently, were considered to be among their closest relatives. The evolution of wing pattern in Geometridae has been neglected since the 1930s. Here, the relationship between wing pattern and venation is examined for Hydriomena costipunctata Barnes andMcDunnough, 1912 and the Hydriomena speciosata (Packard, 1873) group. These two lineages have some of the simplest wing patterns in Hydriomena, consisting of large, well-defined dark and light pattern elements. The relationship between wing pattern and venation varies considerably within and between these lineages and can even vary between the right and left wings on the same individual. Although many different wing patterns were observed among the individuals examined for this study, not one can be reconciled with either of the models that successfully predict the relationship between wing pattern and venation in many other groups of Lepidoptera. This suggests that bands occurring on the wings of Hydriomena are not homologous with those on the wings of butterflies or of Acronictinae (Macroheterocera: Noctuidae), the only other two obtectomeran lineages for which the relationship between wing pattern and venation has been examined in recent years.

Symmetry systems on the wings ofDichromodesGuenée (Lepidoptera: Geometridae) are unconstrained by venation

“…Not only do the wing patterns of Dichromodes violate all predictions about the relationship between the central symmetry system and wing venation, but the highly variable nature of wing pattern within this genus also suggests that wing venation does not exert nearly as strong of a constraint in Geometridae as it does in more early-diverging lineages, such as Micropterigidae and Papilionoidea, and in other macroheteroceran lineages such as Noctuidae. This finding in Dichromodes is consistent with the first contribution in this three-part series on wing pattern in Geometridae, which found no relationship between wing pattern and venation along the costa in Hydriomena species with far simpler wing patterns than those of Dichromodes (Schachat, 2019).…”

“…Adapted from Schachat (2017a) and Schachat & Goldstein (2018). Evaluations of taxa other than Dichromodes in this figure are based on findings published in Schachat & Brown (2015), Schachat & Brown (2016), Schachat & Brown (2018), Schachat (2017b), Baixeras (2002), Brown & Powell (1991), Schachat (2017a), Schwanwitsch (1924), Süffert (1927), Schachat (2019) and Schachat & Goldstein (2018).…”

“…2D), or with neither. The first study in this series focused on very simple wing patterns that consist of dark and light bands (Schachat, 2019). The present study focuses on wing patterns that appear to conform to the nymphalid groundplan in that they contain at least one symmetry system.…”

“…3). Because geometrids in the subfamily Larentiinae are vastly overrepresented in morphological studies of wing pattern (Henke, 1928;Süffert, 1929;Henke, 1933;Schwanwitsch, 1956;Schachat, 2019), Dichromodes expands the phylogenetic scope of this body of knowledge. The primary aim of this contribution is to determine whether the most prominent symmetry system on the wings of Dichromodes conforms to the alternating wing-margin model, the uniform wing-margin model, or neither model.…”

“…First, recent molecular phylogenetic studies have shown that geometrids are not nearly as closely related to butterflies as previously believed, and in fact belong to the more recently-derived clade Macroheterocera (Regier et al, 2009;Mutanen, Wahlberg & Kaila, 2010;Regier et al, 2013;Kawahara & Breinholt, 2014;Heikkilä et al, 2015). Second, recent studies of Macroheterocera in the noctuid subfamily Acronictinae and in the geometrid genus Hydriomena Hübner, [1825] found that wing pattern in these moths has a fundamentally different relationship with venation than that seen in butterflies (Schachat & Goldstein, 2018;Schachat, 2019), highlighting the possibility that morphological generalizations from butterflies may be of little relevance to Macroheterocera. Third, because butterflies are typically diurnal and other moths typically are not, their wing patterns are viewed in different circumstances, leading to different possible functions for wing pattern and selective pressures.…”