Aeginecta, Pessacq, 2018

Pessacq, D. Christopher Rogers Miguel Archangelsky Pablo, 2018, A new genus and species of thamnocephalid fairy shrimp (Branchiopoda: Anostraca) from Argentina (Chubut Province), Nauplius (e 2018021) 26, pp. 1-8 : 2

Aeginecta n. gen.

( Fig. 1 )

Diagnosis. ( Fig. 1A ) Compound eye peduncle extremely short. Frons and anterior surface of antennae II broadened laterally,leaving an intervening slit through which the compound eye may view the area forward on the animal. “Antenna like” appendage absent. Cercopods elongate, as long as abdomen ( Fig. 1F ).

Description. Gonopod proximal portion not retractile, projecting ventrally from segment, bulbous, with an apical, transverse cleft ( Fig. 1D, E ). Proximal nonrectractile portion distally, posterior to cleft with transverse rows of fine denticles. Distal eversible portion minute, lamellar, lying within proximal portion cleft. Distal portion with one lateral and one medial longitudinal row of spines. Spine length 1.4x basal width. Spines separated by 2x their basal width.

Etymology. The genus name is formed of a combination of the Latin word “ aegis ” (from the Greek aigis), meaning “shield”, and the Greek word “ nekton ”, meaning “swimmer”. The name refers to the broadened frons and second antennae which project laterally, leaving a groove through which the eye can view forward. This arrangement is similar to some medieval shields which bore a cleft or slit through which a warrior could see and still be relatively protected.

Comments. The type species of the genus is Aeginecta longicauda n. sp. by designation.

Figures

Figure 1.Aeginectalongicauda n.gen., n.sp. holotype, male:A) Left side of headanterior view.B) Right thoracopodV, anteriorview. C) Genital segment, ventral view. D) Left gonopod, left lateral view. E) Left gonopod, distal view. F) Telson and cercopods, ventral view. Scale bar: A & C) = 2mm; B) = 1.5mm; D & E) = 300 μm; F) = 1mm.