Alona

Damme, Kay Van & Dumont, Henri J., 2009, Notes on chydorid endemism in continental Africa: Matralona gen. n., a monotypic Alonine from the Fouta Djalon Plateau (Guinea, West Africa) (Crustacea: Cladocera: Anomopoda), Zootaxa 2051, pp. 26-40 : 34

Why not Alona ?

Matralona gen. n. is different from Alona sensu stricto, in the current view situated around A. quadrangularis ( O.F. Müller 1776) and related species, a mainly mud-dwelling lineage ( Van Damme & Dumont 2008 a). In fact, there are no similarities with the latter. In “external” characters, M. simoneae differs from the majority of Aloninae . It is a very small species (0.27mm) with setulated labral keel, two main head pores and strong denticles on the posteroventral corner of the valves. The head shield of Matralona gen. n. is not laterally expanded, leaving the labral keel and antennules exposed (in lateral view), and the rostrum is relatively long. In other Aloninae , the head shield is more expanded laterally, protecting cephalic structures. Limb characters too confirm a strong isolation. M. simoneae has a P 6 and a “complete” gnathobase on P 5 (Tables 1 and 2), both considered ancestral conditions (e.g., Van Damme & Dumont 2008 b). Other structures are reduced in comparison to Hexalona -groups (see below). Anterior elements on P 1, the third IDL seta, a soft seta on P 2 and one seta in exopodite of P 3 are absent. The reductions are typical the Coronatella- branch ( Van Damme & Dumont 2008 b; see below). Small body size and the lack of one seta on second antenna can also be regarded as reductions for Matralona gen. n..

The following limb characters are unique within Chydoridae (Table 1). 1. Epipodite on P 1 with deep bifurcation. In Anomopoda , a similar character state is only known in Bosminopsis Richard, 1895 (see Kotov 1997) but not in Chydoridae where there is no or one projection, never two. 2. First limb ODL seta with long setules. This seta is implanted with fine short setules in Aloninae , never with long setules. 3. Modified setae on the endite of fourth limb. The first seta is strongly thickened, the first flaming torch seta has a unique sawlike morphology and the following two setae are strongly reduced. Such modifications are unknown elsewhere in Aloninae . In other Alona -like taxa, flaming torch setae may be well developed, decrease in size, in several stages of reduction (one is lost in Karualona ) but never in the arrangement as in Matralona gen. n.. In Alonopsis Sars, 1862 , a similar peculiar flaming torch seta is also present, but this genus shows further no resemblances with Matralona gen. n. Such a modification may be linked to feeding but its true function remains unknown to date.