Does size matter for horny beetles? A geometric morphometric analysis of interspecific and intersexual size and shape variation in Colophon haughtoni Barnard, 1929, and C. kawaii Mizukami, 1997 (Coleoptera: Lucanidae)

Abstract

Colophon is an understudied, rare and endangered stag beetle genus with all species endemic to isolated mountain peaks in South Africa's Western Cape. Geometric morphometrics was used to analyse intersexual and interspecific variation of size and shape in the mandibles, heads, pronota and elytra of two sympatric species: Colophon haughtoni and Colophon kawaii. All measured structures showed significant sexual dimorphism, which may result from male-male competition for females. Female mandibles were too small and featureless for analysis, but male Colophon beetles possess large, ornate mandibles for fighting. Males had significantly larger heads and pronota that demonstrated shape changes which may relate to resource diversion to the mandibles and their supporting structures. Females are indistinguishable across species, but males were accurately identified using mandibles, heads and pronota. Male C. kawaii were significantly larger than C. haughtoni for all structures. These results support the species status of C. kawaii, which is currently in doubt due to its hybridisation with C. haughtoni. We also demonstrate the value of geometric morphometrics as a tool which may aid Colophon conservation by providing biological and phylogenetic insights and enabling species identification.

Identification, sexual dimorphism, and allometric effects of three psyllid species of the genus Psyllopsis by geometric morphometric analysis (Hemiptera, Liviidae)

“…Males of C. kawaii were significantly larger than C. haughtoni for all structures. Their results support the species status of C. kawaii , which was in doubt due to its hybridization with C. haughtoni (Eldred et al 2016). In another study, Tabatabaei Yazdi and Adriaens (2013) utilized skull shape and size in geometric morphometric analysis to identify four rodent species ( Meriones tristrami Thomas, 1892, Meriones persicus (Blanford, 1875), Meriones vinogradovi Heptner, 1931, and Meriones libycus Lichtenstein, 1823).…”

Molecular and morphometric identification of pistachio psyllids with niche modeling ofAgonoscena pistaciae(Hemiptera: Aphalaridae)

“…Similar results were obtained in the present study, where the differences concern mainly vein Rs as well as the distances between landmark 7 to fore and hind margin, and between landmarks 11 to 6 and 1. Geometric morphometrics has also been used to discriminate species in other insect orders, including Hemiptera (Aghagoli et al ., 2013), Hymenoptera (Mitrovski-Bogdanović et al ., 2014), and Coleoptera (Zúñiga-Reinoso and Benítez, 2015; Eldred et al ., 2016).…”

Geometric morphometric analysis of pronotum shape in two isolated populations of Dorcadion anatolicum Pic, 1900 (Coleoptera: Cerambycidae) in Turkey

“…Although there many studies have found significant differences in pronotum shape in Coleoptera (Pizzo et al, 2006;Ober & Connolly, 2015;Eldred et al, 2016;Li et al, 2016), geometric morphometrics was applied here to Dorcadion for the first time. Combining pronotal shape morphology with phylogenetic analysis Ober & Connolly (2015) showed that the pronotum shape generally reflects phylogenetic relationships, and may be the most important morphological trait for recognizing distinct populations of Scaphinotus petersi Roeschke, 1907 (Coleoptera: Carabidae) in the Arizona Sky Islands.…”