Idiocysta dryadis, Drake & Poor, 1943

Guilbert, Éric, 2005, Morphology and evolution of larval outgrowths of Tingidae (Insecta, Heteroptera), with description of new larvae, Zoosystema 27 (1), pp. 95-113 : 112

In addition to the acquisition of tubercles, their morphology becomes more complex through evolution. The evolutionary sequences are almost the same in Guilbert (2004a) and Lee (1969) studies. In Guilbert’s study, tubercles are short, simple and spiny in “intermediate” species (species between basal species without tubercles and apical species with more complex tubercles). This is the case of I. dryadis and U. vepris . This step is not observed in Lee study. In the next steps species exhibit the different states of tubercles. Dictyla spp. including D. rasilis , and Cochlochila spp. exhibit tubercles ended with a corolla. Monostira spp. and Leptoypha spp. exhibit small, stout, globular tubercles like did A. peltogyne and K. maynei . In Lee’s study, the tubercles become longer, have setae all along ( Stephanitis , Galeatus and Uhlerites spp. ), and acquired ramifications later ( Ammianus , Lasiacantha spp. , T. buddleiae ).

In Guilbert’s study, tubercles acquired ramifications ( C. ayyari and C. mcelfreshi ) before becoming longer and having setae all along ( L. gibbicarina ). Such sequences of tubercle evolution are based on two different small samples of taxa. The evolutionary sequences suggested are general trends, which have to be explored more precisely. Because of irresolution in two apical clades in Guilbert’s study, the question of evolutionary sequences still remains to specify, i.e. to know if evolution of shapes is a linear sequence from simple to ramified tubercles passing through the different other states, or if it is a radiation from simple tubercles to several other states independently.

Seidenstücker (1954) considered the presence of tubercles as “primitive”, because thoracic and abdominal tubercles are lost by the adults, and cephalic tubercles are reduced in adults. However, in some species adults present thoracic relictual tubercles, namely Furcilliger spp. Others have cephalic tubercles not reduced but bifurcate: Belenus spp. and Placotingis merga Drake, 1960 . Such observations suggest heterochony phenomenon. However, the larvae of these species and their phylogenetic position are unknown. If such species have larvae with tubercles that persist at adult stage, it would suggest peadomorphosis. If they do not have tubercles, their presence at adult stage could be apomorphic. Peramorphosis as heterochronic phenomenon was suggested to explain that adults as well as larv a e b e c o m e c o m p l e x d u r i n g t h e e v o l u t i o n ( Guilbert 2004a). Moreover, it was also suggested to explain that larvae become more complex during the development by acquiring more tubercles through immature stages in some species ( Guilbert 2004b). If peramorphosis is observed in a general context of the evolution of Tingidae , can peadomorphosis occur in the same time in particular taxa?