Plutonium

Diagnosis. LBS 2 – 20 with spiracles (figs 5 EG in Bonato et al. 2017). Coxopleuron lacks spine at the place of corresponding process. Prefemur and femur of the ultimate legs lacking spines; pretarsus much longer than tarsal articles taken together and “ expanding ventrally in a sclerotized ridge ” (Bonato et al. 2017: 11) i. e. blade-like.

Number of species. 1. Remarks. Treated as a genus in Di et al. (2010: 51), Edgecombe & Bonato (2011: 395), Bonato et al. (2017: 1); not included in Vahtera et al. (2012 a). The most recent morphological account on Plutonium — Bonato et al. (2017) — lacks information on structure of maxillae 2. As for possible non-monophyly of Plutonium, we agree with Di et al. (2010: 55) who wrote: ” In Plutoniumidae, the morphological analyses … retrieved Theatops as a paraphyletic group, i. e., Plutonium is nested within Theatops ... A three-genus classification … would increase paraphyly rather than lessen it ... We do not place Plutonium in synonymy under Theatops, which would eliminate non-monophyletic taxa from Plutoniumidae … ”. That suggestion was confirmed partially by Bonato et al. (2017: 17), who noted that their molecular data did “ not decisively favour any of the two alternative hypotheses: (1) Plutonium and Theatops represent two separate lineages, which is consistent with a previous hypothesis elaborated on morphological similarities (Shelley, 1997) and in agreement with current taxonomy, (2) Plutonium is a derived lineage within Theatops, which is supported also by previous cladistic analyses on morpho-anatomical data ”. Because of its unique segmental distribution of the spiracles, we think that Plutonium should be kept as a genus at the moment.

Remarks. Treated as a genus in Di et al. (2010: 51), Edgecombe & Bonato (2011: 395), Bonato et al. (2017: 1); not included in Vahtera et al. (2012 a). The most recent morphological account on Plutonium — Bonato et al. (2017) — lacks information on structure of maxillae 2. As for possible non-monophyly of Plutonium, we agree with Di et al. (2010: 55) who wrote: ” In Plutoniumidae, the morphological analyses … retrieved Theatops as a paraphyletic group, i. e., Plutonium is nested within Theatops ... A three-genus classification … would increase paraphyly rather than lessen it ... We do not place Plutonium in synonymy under Theatops, which would eliminate non-monophyletic taxa from Plutoniumidae … ”. That suggestion was confirmed partially by Bonato et al. (2017: 17), who noted that their molecular data did “ not decisively favour any of the two alternative hypotheses: (1) Plutonium and Theatops represent two separate lineages, which is consistent with a previous hypothesis elaborated on morphological similarities (Shelley, 1997) and in agreement with current taxonomy, (2) Plutonium is a derived lineage within Theatops, which is supported also by previous cladistic analyses on morpho-anatomical data ”. Because of its unique segmental distribution of the spiracles, we think that Plutonium should be kept as a genus at the moment.

Type species. Plutonium zwierleini Cavanna, 1881 (by monotypy).