Resolving a century-old case of generic mistaken identity: polyphyly of Chitoniscus sensu lato resolved with the description of the endemic New Caledonia Trolicaphyllium gen. nov. (Phasmatodea, Phylliidae)

Abstract

With every molecular review involving Chitoniscus Stål, 1875 sensu lato samples from Fiji and New Caledonia revealing polyphyly, the morphology from these two distinct clades was extensively reviewed. Morphological results agree with all previously published molecular studies and therefore Trolicaphylliumgen. nov. is erected to accommodate the former Chitoniscus sensu lato species restricted to New Caledonia, leaving the type species Chitoniscus lobiventris (Blanchard, 1853) and all other Fijian species within Chitoniscus sensu stricto. Erection of this new genus for the New Caledonian species warrants the following new combinations: Trolicaphyllium brachysoma (Sharp, 1898), comb. nov., Trolicaphyllium erosus (Redtenbachher, 1906), comb. nov., and Trolicaphyllium sarrameaense (Größer, 2008a), comb. nov. Morphological details of the female, male, freshly hatched nymph, and egg are illustrated and discussed alongside the Chitoniscus sensu stricto in order to differentiate these two clades which have been mistaken as one for decades.

Leaves that walk and eggs that stick: comparative functional morphology and evolution of the adhesive system of leaf insect eggs (Phasmatodea: Phylliidae)

“…Surface covered with minor mushroom-like bumps. This type is described as a characteristic feature of Trolicaphyllium [ 32 ] and is not present in other lineages, Fig. 3 A.…”

“…It is likely that differences in the morphology of the exochorionic appendages are due to adaptations to different substrates the eggs should more likely be attached to, such as differences in the roughness, hydrophobicity or hydrophilicity, or the presence of certain features (like trichomes) on the plant leaves they should adhere to. Some egg traits that are characteristic for certain lineages have been assumed to generate adhesion based on their morphology, as for instance in Trolicaphyllium [ 32 ]. Features of the egg morphology of Phylliidae have been used frequently for taxonomic characterisation of certain subgroups as the eggs often possess prominent diagnostic traits distinguishing closely related and extremely similar taxa [e.g.…”

“…3 Exemplary egg morphotypes. A Cuboid smooth, Trolicaphyllium sarrameaense (from [ 32 ]). B Pentagonal spongy, Nanophyllium asekiense (Größer, 2002) .…”

Convergent Evolution of Adhesive Properties in Leaf Insect Eggs and Plant Seeds: Cross-Kingdom Bioinspiration

“…All three scenarios require strong, reliable attachment, as shown for the adhesive system of P. philippinicum . Based on the shape of the eggs and their appendages, several other phylliid species likely possess an adhesive capability as well [ 67 ], but some seem to have different glue properties and seem to attach better on hydrophobic than hydrophilic substrates (pers. obs).…”

Figure 13 from: Cumming RT, Le Tirant S (2022) Three new genera and one new species of leaf insect from Melanesia (Phasmatodea, Phylliidae). ZooKeys 1110: 151-200. https://doi.org/10.3897/zookeys.1110.80808

“…Additionally, in many cases these single morphological feature-based relationships did not agree with well-supported molecular based phylogenies (for example, in females the ventral color of the coxae can either be the same color as the surrounding tissue or a vibrant different variety of colors (like is seen in Chitoniscus Stål, 1875 and Phyllium Illiger 1798); however, these clades have not been recovered as sister to each other (Bank et al 2021)). Instead, it has become apparent that phylliid relationships must be examined from multiple lines of evidence whenever possible (such as the erection of the Trolicaphyllium Cumming et al 2021a from the Chitoniscus Stål, 1875 which was supported by numerous molecular based studies and 23 morphological characters; see Cumming et al 2021a and citations therein).…”