Palaemon mercedae, % Pereira, 1986

Carvalho, Fabrício L., Magalhães, Célio & Mantelatto, Fernando L., 2019, A molecular and morphological approach on the taxonomic status of the Brazilian species of Palaemon (Decapoda, Palaemonidae), Zoologica Scripta 49 (1), pp. 1-16 : 4-6

Palaemon mercedae

This species has a high genetic differentiation in relation to the other species of Palaemon s.s., with uncorrected divergence of 0.1900 (±0.0134) for the 16S gene, 0.2305 (±0.0169) for COI and 0.194 (±0.0176) for H3 (Tables S3–S5). The time of divergence between P. mercedae and Palaemon s.s. was 21.3 Mya (HDP 17.5–25.0 Mya).

Palaemon sensu stricto

Among the species of Palaemon s.s., only P. northropi was not recovered as monophyletic, being intercalated by P. floridanus specimens. The time of divergence between the P. northropi + P. floridanus clade and the other species of Palaemon s.s. was estimated at 15.9 Mya (HDP: 13.2–18.9 Mya). Palaemon paivai was recovered as monophyletic, with a genetic divergence of 0.0290 (±0.0073) for 16S, 0.1029 (±0.0115) for COI and 0.0089 (±0.0049) for H 3 in relation to its sister, P. ritteri . In addition, a species with no previous record in Brazil was identified ( Palaemon octaviae ), which was recovered as close to P. argentinus . The genetic divergence between P. octaviae and P. argentinus was 0.1021 (±0.0133) for 16S, 0.11130 (±0.0128) for COI and 0.0365 (±0.0103) for H3, with time of divergence estimated at 7.5 Mya (HDP 5.4–9.5 Mya).

Intraspecific variability in Palaemon s.s. species was lower than that found in the “ Alaocaris ” species (Table S6). All species showed genetic divergence lower than 0.01 for 16S and COI and 0.001 for H3. The clade P. northropi + P. floridanus showed a small structuring, with a divergence of 0.0096 (±0.0020) for COI.