Morphological reassessment of the movable calcar of delphacid planthoppers (Hemiptera: Fulgoromorpha: Delphacidae)

Abstract

This study presents the morphology of calcar in adult Delphacidae based on representatives of the genera Ugyops Guérin-Meneville, 1834, Notuchus Fennah, 1969 (Ugyopini), Asiraca Latreille, 1798 (Asiracini), Kelisia Fieber, 1866, (Kelisini), Stenocranus Fieber, 1866 (Stenocranini), Chloriona Fieber, 1866, Megadelphax Wagner, 1963, Muellerianella Wagner, 1963, Javesella Fennah, 1963, Conomelus Fieber, 1866, Euconomelus Haupt, 1929, Hyledelphax Vilbaste, 1968, Stiroma Fieber, 1866, Struebingianella Wagner, 1963 and Xanthodelphax Wagner, 1963 (Delphacini). We used SEM electron microscopy, to define seven types of calcar structure (Types 1, 2, 5, 6, 7, 8, and 9) based on combinations of characters including shape, number of teeth and differentiation of sensory structures in species from fifteen genera. Additionally, two other types (Types 3 and 4) were determined based on the calcar descriptions from previous studies. Similarities and differences in calcar structure and function were discussed and emerging relationships between planthopper species and their particular habitats were indicated.

Phylogeny and diversification of planthoppers (Hemiptera: Fulgoromorpha) based on a comprehensive molecular dataset and large taxon sampling

“…From a morphological perspective this result is counter intuitive, rejecting the most significant and unique apomorphic character of Delphacidae with the presence of a movable and apical metatibial spur exposing a gradual transformation series of the spur conformation (Markevich et al, 2021). It suggests two possible scenarios: (1) the spur appeared twice, independently in Protodelphacida in which it remained quite simple, more or less conical, never denticulated, versus flattened and always dentated in Eudelphacida (Asche, 1990;Markevich et al, 2021); or (2) the spur appeared once in Delphacoidea much probably unarmed, secondly disappearing in Cixiidae therefore miming the plesiomorphic pattern of other planthoppers, leading to consider them as 'cryptic' delphacids. While this second scenario would apparently be more parsimonious (one apomorphic acquisition secondarily absent in Cixiidae), we would favor the first one (two independent acquisitions) because up to now, all Cretaceous fossils observed exhibit a cixioid pattern, without any metatibial spur, which should have been observed in their common ancestor (Luo et al, 2021).…”