Acentrella Bengtsson, 1912

Gattolliat, Jean-Luc, Samraoui, Boudjema, Benhadji, Nadhira, Kechemir, Lina, Zrelli, Sonia, El Yaagoubi, Sara, El Moutaouakil, Majida El Alami & Sartori, Michel, 2023, Baetidae (Baetidae, Ephemeroptera) in the Maghreb: state of the art, key, and perspectives, ZooKeys 1139, pp. 137-163 : 137

1. Acentrella Bengtsson, 1912

Diagnosis.

1) Very reduced paracercus; 2) stocky mouthparts; 3) head compressed dorsoventrally; 4) presence of a complete row of long thin setae on the dorsal margin of tibia; 5) villopore present on the ventral margin of fore femora.

Remarks.

In the past, Acentrella was considered as a subgenus of Baetis ( Müller-Liebenau 1969). Confusions with species with reduced paracercus ( Baetis pavidus or the subgenus Baetis Patites ) can be avoided by the examination of the mouthparts, especially of the mandibles as well as the distal margin of the tergites. The abdominal tergites also present a characteristic dark brown pattern (Fig. 3A ).

Two species of Acentrella are reported in the Maghreb: Acentrella cf. sinaica Bogoescu, 1931 and Acentrella almohades Alba-Tercedor & El-Alami, 1999. Acentrella sinaica was originally described from Romania, then reported from several countries from Central and South Europe. This species is not abundant but widely distributed in North Algeria and North-West Tunisia. Maghrebian populations seem morphologically very similar to those from central Europe. However, molecular preliminary results suggest that the Maghreb populations most probably belong to a new undescribed species ( Benhadji et al. 2020). Acentrella almohades is originally described from the Rif mountains and middle Atlas as well as from south-west of Spain. The two species do not seem to co-occur. They can be separated by the length of the setae of the dorsal margin of femora (longer in A. cf. sinaica than in A. almohades ) and the number of regular rows of stout setae at apex of paraglossa (three rows in A. cf. sinaica , four rows in A. almohades ) ( Alba-Tercedor and El-Alami 1999).

Figures

Figure 3. Baetidae: larvae in toto in dorsal view (except 3 C lateral view) A Acentrella cf. sinaica B Alainites oukaimeden C Alainites sadati D Baetis (Patites) sp. E Baetis (Baetis) pavidus.