Clavella Oken 1815

Consideration of Clavella - Branch phylogeny When Kabata (1979) proposed his phylogenetic tree of Lernaeopodidae based on morphology, he established its main branches: Salmincola branch, Charopinus Branch, Brachiella Branch, Lernaepoda branch, and Clavella Branch. For Clavella branch, he defined several sub-branches. The first sub-branch (A) included Clavellisa Wilson, C. B. 1915, Euclavellisa Heegaard, 1940, Clavellopsis Wilson, C. B. 1915, and Clavellodes Wilson, C.B. 1915. On the opposite side, sub-branch (B) comprised Clavella Oken, 1815 —a diverse genus—along with sub-branch (C), which included Anaclavella Heegaard, 1940 and Clavellominus Kabata, 1969. More distally, sub-branch (D) emerged, containing Proclavellodes Kabata, 1967, Alella, Leigh-Sharpe, 1925, and Kabatazu s Özdikmen, 2008 (formerly Advena; Kabata 1979). Kabata also positioned Clavellistes within sub-branch (B) alongside Clavella. At that time, Clavella branch consisted of 11 Genera. Since then, several new genera have been described within this branch, including Nudiclavella Ho, 1975 (whose status remains uncertain according to Kabata 1979), Mixtio Kabata, 1990, Pseudomixtio Kabata, 1990, and Clavellotis Castro & Baeza 1984 (following the transfer of some species from Clavellopsis to Clavellotis by Kabata 1990). More recently, Maxiclavella and Praeclavella, were separated from C lavella (Castro et al., 2022). Further taxonomic revisions are likely as suggested in the present study, particularly regarding species such as C. stellata, whose classification requires verification, along with the true placement of Kabatazus (= Advena) within the Clavella branch. A partial molecular analysis using representatives of this branch, based primarily on COI and 28s genes, provides insight into their phylogenetic relationships. Although COI is not strictly used for phylogenetic reconstruction, it has been employed in similar cases (Sebone and Dippenaar 2024), and in other arthropods, such as Orthopteran (Lü et al., 2012) to infer evolutionary relationships. In this study, molecular data support Clavellisa as a basal taxon relative to Clavella, which is also consistent with morphological traits. Clavellisa retains a biramous second antenna and a mandible with secondary dentition, whereas Clavella exhibits a uniramous antenna (or at least a highly reduced exopod) and a mandible with primary dentition, though some species may bear a single secondary tooth). This confirms the evolutionary placement of Clavellisa and its relationship with other genera analyzed at the time. However, the phylogenetic positions of other genera in sub-branch (A) alongside Clavellisa may require reassessment due to notable morphological differences, particularly in body structure (e.g. cephalothorax versus trunk orientation) and mandibular dentition. The present study also supports a clade containing Clavellotis and Alella, though the latter's placement may not align with Kabata’s (1979) classification, given differences in maxilla development and primary dentition. Additionally, the results suggest a close relationship between Clavella and Maxiclavella (Castro et al., 2022), while Praeclavella (Castro et al., 2022) appears to have diverged before the diversification of Clavella. Overall, these findings indicate that new phylogenetic relationships may emerge among the genera currently assigned to the Clavella branch, leading to potential taxonomic reassignments and descriptions of new genera (e.g., Castro et al., in litteris).