A new species of Notodiaptomus from the Amazon basin (Crustacea, Copepoda, Calanoida, Diaptomidae)

Abstract

A new Diaptomidae species is presented from the Neotropical region. It was found in two Amazonian lakes, Ressaca and Arapujá, both in Pará State, Brazil. The lakes are 400 km apart and threatened by the building of reservoirs for hydropower generation and pollution by human settlements. The new species resembles N. paraensis Dussart & Robertson, 1984, but it can be distinguished from this species and other congeners in having a special process on the fifth leg basis of the male, by the place of insertion of lateral spine in the last segment of right P5 of male, the shape and relationship between length and width of segments of male and female P5 exopodite 2 with stout inner process bearing short setules and outer small spine, exopodite 3, with two terminal setae, outer smaller; endopodite 1-segmented with one subterminal seta and oblique comb of spinules, the presence of a line of dorsal spinules at the distal margin of thoracic somites in both sexes. A brief comparison with other Notodiaptomus species is presented in the discussion.

Biological Systematic of the genusNotodiaptomusKiefer 1936 (Copepoda: Calanoida)

“…Truly, the species of Reid (1987) has a closer evolutionary relationship to N. paraenses (node g) through the common and exclusive ancestor reconstructed with antenna endopod actual 3-segmented (char 990; 1►2; CI = 0.50; RI = 0.66), mandible coxal gnathobase with protuberance not proeminente on caudal margin (char 1074; 1►2; CI = 0.50), male fifth right swimming leg basis with inner protuberance distally (char 2293; 1/2►3; CI = 0.50; RI = 0.50), male fifth right swimming leg exopod 2 with outer spine lesser than the length of the exopod 2 beyond to 2 times its size (char 2405; 1►2; CI = 0.12; RI = 0.30), and female right antennule not extending beyond caudal rami (char 2548; 1►2; CI = 0.12; RI = 0.12). Previattelli et al (2017) when reporting the organisms of N. nelsoni related close to those of N. paraensis through similarities of male metasome segments, male fifth right leg coxa, and female fifth swimming legs. Our results suggest refutation of this hypothesis and indicate that N. organisms have a closer evolutionary relationship to N. anisitsi and N. santafesinus (node k) through the exclusive ancestor retrieved with first swimming legs coxa with inner distal seta with length surpassing to basis (char 1451; 2►1; CI = 0.16; RI = 0.50), male fifth right swimming leg coxa with distal process projecting over basis beyond the first third posteriorly (char 2269; 1►2; CI = 0.11; RI = 0.20), male fifth right swimming leg exopod 2 with outer spine lesser than the length of the exopod 2 1.5x its size (char 2407; 2►1; CI = 0.14; RI = 0.40), and female fourth and fifth metasome segments fused partially (char 2448; 1►2; CI = 0.11).…”

“…Over time, other species were included in Notodiaptomus, through taxonomic recombination or original description. The most recent are N. simillimus Cicchino, Santos Silva & Robertson 2001, N. dentatus Paggi 2001, N. cannarensis Alonso, Santos-Silva & Jaume 2017, and N. nelsoni Previattelli, Perbiche-Neves & Rocha 2017. Currently, there are 37 species accepted in Notodiaptomus (Walter & Boxshall, 2023), which are distributed from Antigua and Barbuda (Netherlands Antilles, Central America) to Argentina, 24 of them occur in Brazil (Santos-Silva, 2008), some with more careful descriptions, well-done and detailed illustrations, but the vast majority still with serious deficiencies in this aspect.…”

“…BRAZIL. Pará: Arapujá Lake, 3°12'54"S, 52°11'28"W, Xingu River Basin, in front of Altamira; Arapujá Lake, Xingu River, Altamira City (Previattelli et al, 2017).…”