Genetic analysis of two Alella spp. (Siphonostomatoida: Lernaeopodidae) supports their validity and justifies a new genus for Alella igillimpethu Erasmus, Hadfield, Wepener & Smit, 2023

The erection of a new genus to accommodate Alella igillimpethu Erasmus, Hadfield, Wepener & Smit, 2023 as Simplalella igillimpethu gen. nov. et comb. nov. is proposed, based on molecular and morphological analyses. The new genus is closely related in the phylogenetic tree to Clavellotis dilatata (Kryer, 1863) but according to genetic divergence, it is more closely related to Parabrachiella merlucci (Bassett-Smith, 1896), Praeclavella nasalis Castro Romero, Montes & Martorelli, 2022, and Praeclavella caudata (Castro Romero & Baeza- Kuroki, 1985) (19%). A. macrotrachelus (Brian, 1906) and A. canthari (Heller, 1865) are closely related, with 16% genetic divergence between them. Despite their confirmed validity, the cryptic species within the genus show no discernible morphological differences. A revision of the other species currently included in Alella Leigh-Sharpe, 1925, based on molecular data, is recommended to clarify their true taxonomic position. The molecular analysis also reveals a novel placement of Clavellisa Wilson C.B., 1915, which appears basal to all other analyzed Lernaeopodidae, whereas in previous phylogenies of Lernaeopodidae it was placed at the base of the Clavella Oken, 1815 branch. This new position could be explained by the presence of a short uropod in Clavellisa, along with vestigial thoracic legs in some speciesfeatures that suggest a primitive condition.