Separation of Anthalona gen.n. from Alona Baird, 1843 (Branchiopoda: Cladocera: Anomopoda): morphology and evolution of scraping stenothermic alonines

Abstract

We move the freshwater cladocerans Alona verrucosa Sars, 1901 and related species from the lump genus Alona Baird, 1843 (Anomopoda: Chydoridae: Aloninae) to Anthalona gen. n. We revise the group and describe five new taxa from tropics and subtropics: Anthalona simplex n. sp., DR Congo, A. harti n. sp., Africa (with two subspecies), A. acuta n. sp., Brazil and A. obtusa n. sp., Borneo. Anthalona is a genus of relatively small-sized, stenothermic Aloninae with specializations for scraping. Within the subfamily, the new genus is closest to Karualona and Coronatella. We discuss possible homoplasy of limb characters between latter and Anthalona. The genus can be considered an important case study in an evolutionary trend towards oligomerization of limb structures at low taxonomical levels and within an extant crustacean lineage. Composition of the genus reflects a complex history. Species with unusual morphologies (A. brandorffi, A. simplex n. sp.) appear basal in our phylogeny and may be relicts, in comparison to a pantropical A. verrucosa complex of similar forms. Several species may coexist in a single water body such as A. acuta n. sp. and A. verrucosa in the Neotropics, suggesting niche separation.

Position of the dentifera-group in the Coronatella-branch and its relocation to a new genus: Magnospina gen. n. (Crustacea, Chydoridae, Aloninae)

“…n. (which has the armature of IDL setae similar to genus Coronatella ). A similar trend was observed in species of Anthalona whose evolution of IDL setae are related to feeding strategies (Van Damme et al 2011a). Thus, distinct evolutionary pressure on the food handling should be considered to explain differences observed on the IDL setae of Magnospina gen. n. species.…”

“…n.; however, analogous variation in these structures was already observed in Euryalona (Rajapaksa and Fernando 1987). Species-groups of Alona sensu lato, such as the costata -group (Sinev 1999b, 2001a, 2008, Van Damme and Eggermont 2011, Van Damme et al 2011b), verrucosa -group (Van Damme et al 2011a, Sinev and Kotov 2012), rectangula -group (Van Damme and Dumont 2008b, Sousa et al 2015a), and pulchella -group (Sinev 2001b, c, 2009, Sinev and Silva-Briano 2012, Van Damme et al 2013, Sousa et al 2015b) also have differences in structures on head, postabdomen, and limbs.…”

“…Generally, specialized species have their morphology linked to habitat conditions (Van Damme et al 2003, Kotov 2000a, b, Kotov 2006, Van Damme et al 2009, Kotov et al 2010, Van Damme and Sinev 2011, Van Damme et al 2011a, Sinev 2014), but, apparently, this is not case of the two species from the dentifera -group, because they may occur in different kinds of habitats (Sinev and Sanoamuang 2007, Güntzel et al 2010, Sousa et al 2012, Kotov et al 2013, Van Damme and Sinev 2013). …”

“…Anthalona males have a short basal spine, well-developed setules of the lateral fascicles on the postabdomen and lateral aesthetascs on antennules absent (Van Damme et al 2011a, Sinev and Kotov 2012). Karualona males has postabdomen very similar to the one observed in Anthalona , with well-developed lateral fascicles on the postabdomen and a very short basal spine on the postabdominal claw.…”

“…Frey, 1967. Because of the polyphyletic nature of Alona (Sacherová and Hebert 2003, Elmoor-Loureiro 2004, Eliáz-Gutiérrez et al 2008; Van Damme et al 2010), allocations of species groups to different genera were made: Phreatalona , which corresponds to the protzi -complex (Van Damme et al 2009); Coronatella , which corresponds to the rectangula -complex (Van Damme and Dumont 2008a); Brancelia (Van Damme and Sinev 2011), which corresponds to the hercegovinae -complex; and Anthalona Van Damme, Sinev & Dumont, 2011, which includes species of the verrucosa -complex (Van Damme et al 2011a). Most recently, Sinev (2015a) included the pulchella -group in Ovalona Van Damme & Dumont, 2008.…”