Coronatella Anthalona A. verrucosa Coronatella A. rectangula A. monacantha Alona Coronatella Anthalona Coronatella Anthalona Coronatella Anthalona Anthalona Coronatella Aloninae Anthalona Karualona Anthalona Anthalona Coronatella Anthalona C. holdeni A. acuta Coronatella Anthalona Separation of Anthalona gen. n. from Alona Baird, 1843 (Branchiopoda: Cladocera: Anomopoda): morphology and evolution of scraping stenothermic alonines DAMME, KAY VAN SINEV, ARTEM YU DUMONT, HENRI J. Zootaxa 2011 2011-05-11 2875 1 1 64 62MG2 2764912 Dybowski & Grochowski 1894 [346,489,1590,1616] Branchiopoda Coronatella Animalia Diplostraca 56 57 Arthropoda genus    Coronatellaand  Anthalona  gen. n.are similar enough for earlier authors to regard  A. verrucosaas a member of  Coronatellarectangula-group (e.g., Daday 1910, Jenkin 1934;  A. rectangula-group). Also the presence of tubercles in both, has lead to confusion (e.g., Johnson 1956b). Important similarities include (  VanDamme & Dumont 2008b): 1) five pairs of limbs with reductions, typical for the Coronatella-branch (IDL with two setae, reduction of anterior setae in P1, exIII with six setae, no gnV); 2) specialized setal armature (IDL on P1); 3) The  A. monacanthagroup (to be removed from  Alona) has all characters of  Coronatella, but some peculiarities of  Anthalona(strong armature IDL on P1, denticle on labrum) as well, hence seems intermediate; 4) In general dimensions of body and postabdomen,  Coronatellaand  Anthalona  gen. n.look nearly identical.   Coronatellaand  Anthalonaseem both natural assemblages with a separate evolution. The head pore configuration is distinct and stable in each genus (two + cosmaria in  Anthalonaversus three + no lateral pores in  Coronatella). The phylogenetic importance of head pores in the Aloninaemay be overrated, but the difference is significant in that the typical head pore typearose only once in an ancestral  Anthalona, maybe even from the  Karualona type. It gave rise to a subtle diversity of head pore arrangements in  Anthalona. The same can be said for postabdomen armature (lateral spines thicker and basal spine shorter in  Anthalona) and other specific characters ( Fig. 29). In the antennae of  Coronatellaand  Anthalona, strong changes and specialisations have occurred independently, suggesting important plasticity in these traits (e.g.,  C. holdeniand  A. acuta). The limb characters shared by both  Coronatellaand  Anthalona  gen. n.are mainly reductions. As a general trend in the evolution of these microcrustaceans (reduction of setae), such reductions may either have arisen independently or stem from a common ancestor.  Similarity in morphological form may be a result of a reversal, close common ancestry, parallel evolution or convergence. Homoplasy may occur under similar adaptive pressures or by evolutionary constraints (constraints to structural solutions; e.g.,  Wake1991). The similarities in body size and postabdomen between  Coronatellaand  Anthalonamay result from such constraints, although details on their feeding and ecology are yet to be investigated. Reductions on limbs in  Coronatellaand  Anthalonamay also be correlated with miniaturization; both are among the smaller Aloninaegenera. In the  Alonaguttata-group for example, which belongs to an entirely different lineage (of six-limbed  Alona), reductions seem correlated with a decrease in body size. In any case,  Anthalonaand  Coronatellaare examples of the typical general small, successful  Alonabody shape. However, closer examination shows that comparative body shapes of  Anthalonaspeciesare not so similar ( Figs 27–28).   Coronatellaand  Anthalona  gen. n.do not necessarily share a close common ancestor. Evolutionary pressures under similar conditions and/or constraints in the Aloninae“Bauplan” may have lead to homoplasy in external and internal characters, with body shape, postabdomen, even limbs, similar. It results in a small model, successful in littoral environments. An independent test to see whether  Coronatellaand  Anthalonashare a close common ancestor is by molecular analysis ( VanDamme & Dumont, unpubl.), not included in this study. It is this general small “  Alona”body shape that caused many of our historical taxonomical problems in the lump genus ( VanDamme et al., 2010)