Macrobrachium jelskii

Vera, Ana Luiza, Carvalho, Fabrício Lopes & Mantelatto, Fernando Luis, 2017, Redescription of the freshwater shrimp Macrobrachium jelskii (Miers, 1877) (Caridea, Palaemonidae), Zootaxa 4269 (1) : -

Key to differentiate Macrobrachium jelskii , M. amazonicum and M. acanthurus

1 Distal enlargement of the carpus of the second pereiopod gradual ( Figure 6 a); rostrum distinctly surpasses the scaphocerite; rostrum has an evident portion without teeth ( Figure 7 a); internal pair of posterior spine of the telson at most 2 times longer than the median apex in small individuals; internal pair of posterior spine of the telson does not reach the median apex in adults ( Figure 8 a).............................................................................. M. amazonicum

- Rostrum reach or slightly overreach end of the scaphocerite; rostrum does not have an evident portion without teeth ( Figures 7 b and 7c); internal pair of posterior spine of the telson surpasses the median apex and is more than 2 times longer ( Figures 8 b and 8c)............................................................................................. 2

2 Carpus of the second pereiopod similar to the chela length, chela longer than half of the carapace length, distal enlargement of the carpus gradual ( Figure 6 b)............................................................... M. acanthurus

- Carpus of the second pereiopod noticeably longer than the chela, distal enlargement of the carpus abrupt ( Figure 6 c)..................................................................................................... M. jelskii

Figures

FIGURE 6. Ventrolateral view of the left second pereiopod of a) M. amazonicum; b) M. acanthurus; c) M. jelskii. Scale bar equal to 0.5 mm.

FIGURE 7. Right lateral view of the anterior portion of the carapace of a) M. amazonicum; b) M. jelskii; c) M. acanthurus. Scale bar equal to 0.5 mm.

FIGURE 8. Dorsal view of the distal portion of the more common telson shape in adults of a) M. amazonicum; b) M. jelskii; c) M. acanthurus. Scale bar equal to 0.5 mm.