Coronatella paulinae Sousa, Elmoor-Loureiro and Santos, 2015

Sousa, Francisco Diogo R., Elmoor-Loureiro, Lourdes M. A., Menéndez, Rosa Maria & Maia-Barbosa, Janaina Horta and Paulina Maria, 2016, Description of the male of Coronatella paulinae (Crustacea, Branchiopoda, Chydoridae) with an identifi cation key for the genus based on the male morphology, Nauplius (e 2016018) 24, pp. 1-8 : 3-5

Coronatella paulinae Sousa, Elmoor-Loureiro and Santos, 2015

Description. Parthenogenetic female.For description and diagnosis, see Sousa et al. (2015).

Adult Male. Habitus ( Fig. 1 ). Smaller than the female, length 0.21–0.24 mm, about 1.6 times as long as it is height; maximum height close to intermediate point of the body; without dorsal keel.

Head ( Fig. 1 ). Rostrum relatively short, rounded, not projected; ocellus and eye of similar sizes; three main head pores connected by a narrow connection, median pore smaller than proximal and distal ones, IP about three times longer than the PP, lateral head pores tiny and inserted at same level as the median main head pores ( Fig. 4 ). Labral keel wide in a lateral view, relatively short, naked; anterior portion convex with a slight projection, apex rounded ( Fig. 1 ).

Carapace ( Figs. 1, 2 ) relatively elongated, longitudinal lines present; ventral margin armed with 22–24 slightly plumose setae not differentiated in groups, followed by fine spinulae, the most proximal spinulae not exceeding the line of the posterior margin; fine and short spinulae between ventral setae present. Posteroventral corner without denticles.

Antennules ( Fig. 3 ). Not exceeding the tip of rostrum, about two times as long as wide: three rows of setulae similar in length on the antennular body.Eleven apical aesthetascs of different lengths, shorter than the length of the antennular body. Sensory seta about 1.5 times shorter than the length of the antennular body. Male seta short and robust, not sharp, about 4.3 times shorter than the length of the antennular body, inserted at the distal third of the antenular body.

Thorax ( Fig. 1 ) two times longer than the abdomen; one row of abdominal setae present.

Postabdomen ( Figs. 5, 6 ). Moderately rectangular, smaller than the female’s, about 2.3–2.6 times longer than its height, narrowing towards the distal portion; anal and postanal margin similar in length; postanal angle relatively well defined; postanal margin armed with 4–5 groups of unmerged setulae, the distalmost being longer; 7–10 lateral fascicles, distalmost fascicles exceeding the marginal line; anal margin with spinulae arranged in three groups; gonopores opening ventrally, subapically to the postabdominal claw. Postabdominal setae about two times longer than the postabdominal length, bisegmented, distal segment setulated.Postabdominal claw smaller and more robust than in the female, tip acute; pecten formed by thick and short spinulae. Basal spines slender, longer than the mid-length of the postabdominal claw, straight or slightly curved near the tip; with a row of fine spinulae inserted on its base.

Limb I ( Fig.7 ).Smaller than the female’s, copulatory hook U-shaped, arms relatively similar in length. Copulatory brush present; seta of the copulatory brush with about 0.7 of the length of the male seta on the IDL; five clusters of long setulae inserted on the body of the limb. IDL with two setae (2–3) of different lengths and armed with short proximal spines; seta of the ODL about 1.7 times longer than the smallest IDL seta (2), slightly serrated. Male seta relatively long (ms), similar in length to the smallest IDL seta (2).

Other limbs similar to those of the parthenogenetic female (see Sousa et al., 2015).

Remarks. The morphological traits presented in the description of Coronatella paulinae males are widely used to discriminate males from females in Chydoridae . The shape of the male postabdomen of C. paulinae resembles the one in Coronatella poppei (Richard, 1897) , Coronatella rectangula (Sars, 1862) , and Coronatella circumfimbriata (Megard, 1967) . However, it can be distinguished from these other species by the armature of the basal spine, which is

Figures

Figures 1–7. Coronatella paulinae Sousa, Elmoor-Loureiro and Santos, 2015. Male from Gambazinho Pond, Minas Gerais state, Brazil: 1, Habitus, lateral view, adult; 2, Posteroventral corner of the carapace; 3, Antennule; 4, Head pores; 5, Postabdomen; 6, Idem, outline, arrows showing the postanal angle and the variability of basal spine shape; 7, Limb I. Scale bars: 1 = 50 µm; 2, 3, 5, 7 = 25 µm; 4 = 12 µm. Abbreviations: cbs = copulatory brush seta; en = endite; ep = epipod; IDL = inner distal lobe; ms = male seta; ODL = outer distal lobe.