Abstract
Description and meristic analysis of eleven species of Microcyclops recorded in America were performed based on the examination of type specimens and fresh material. Microscopic analysis of oral appendages, such as the shape and armature of the distal coxal endite of the maxilla, the ornamentation on the caudal surface of the antenna, and the intercoxal sclerites and armament of the inner basis of all swimming appendages, were characteristics that allowed the differentiation between species. Among these species, our study confirmed the synonymy of Microcyclops diversus Kiefer, 1935 with Microcyclops ceibaensis (Marsh, 1919). The results of our observations showed that Microcyclops alius (Kiefer, 1935) is a junior synonym of Microcyclops dubitabilis Kiefer, 1934; the latter being confirmed as a valid species. Also, it is proposed that the records of Microcyclops rubellus (Lilljeborg, 1901) and Microcyclops varicans (Sars, 1863) in America should be revised as there are serious doubts about their distribution in America. The analysis suggested that Microcyclops anceps pauxensis Herbst, 1962 is distinct from Microcyclops anceps var. minor Dussart, 1984 and that both are likely different from Microcyclops anceps anceps (Richard, 1897). Finally a full morphological description of adult females of Microcyclops inarmatus sp. n. is presented.
Highlights
IntroductionIn America, 16 species and subspecies of Microcyclops Claus, 1893 have been described and recorded: M. alius (Kiefer, 1935), M. anceps anceps (Richard, 1897), M. anceps pauxensis Herbst, 1962, M. anceps var. minor Dussart, 1984, M. ceibaensis (Marsh, 1919), M. dubitabilis Kiefer, 1934, M. echinatus Fiers, Ghenne & Suárez-Morales, 2000, M. elongatus (Lowndes, 1934), M. finitimus Dussart, 1984, M. furcatus (Daday, 1905), M. mediasetosus Dussart & Frutos, 1985, M. medius Dussart & Frutos, 1985, M. pumilis Pennak & Ward, 1985, M. rubellus (Lilljeborg, 1901), M. diversus Kiefer, 1935, and M. varicans (Sars, 1863).In her publication of an identification key for South American cyclopoids, Reid (1985) proposed that Microcyclops diversus is a probable synonym of M. ceibaensis (in 1986, this opinion was based on similarities in the fourth leg observed by the same author) and that M. anceps var. minor is a synonym of M. anceps pauxensis. Rocha (1998) proposed a set of morphological features that would be useful for distinguishing five species previously recorded in Brazil and suggested that M. alius is a possible synonym of M. dubitabilis
The features that separate the specimens of these species were the insertion of the caudal seta II (69.5% in M. ceibaensis vs. 73.2% in M. echinatus); the length and width ratio of the caudal ramus is 3.6 in M. ceibaensis while 5.9 in M. echinatus; the presence of spines on the fifth pediger in M. echinatus vs. absence of these spines in M. ceibaensis; and the ornamentation of the inner basis of P4 with spine-like setae in M. ceibaensis vs. short setae plus hair-like setae in M. echinatus
The structure of P1, P3, P4, and P5; the armament of the caudal surface of the antenna, the number of setae on each endopodal segment of the antenna, and the entire morphology of the urosome, and the caudal ramus in M. diversus are indistinguishable from the states found in M. ceibaensis
Summary
In America, 16 species and subspecies of Microcyclops Claus, 1893 have been described and recorded: M. alius (Kiefer, 1935), M. anceps anceps (Richard, 1897), M. anceps pauxensis Herbst, 1962, M. anceps var. minor Dussart, 1984, M. ceibaensis (Marsh, 1919), M. dubitabilis Kiefer, 1934, M. echinatus Fiers, Ghenne & Suárez-Morales, 2000, M. elongatus (Lowndes, 1934), M. finitimus Dussart, 1984, M. furcatus (Daday, 1905), M. mediasetosus Dussart & Frutos, 1985, M. medius Dussart & Frutos, 1985, M. pumilis Pennak & Ward, 1985, M. rubellus (Lilljeborg, 1901), M. diversus Kiefer, 1935, and M. varicans (Sars, 1863).In her publication of an identification key for South American cyclopoids, Reid (1985) proposed that Microcyclops diversus is a probable synonym of M. ceibaensis (in 1986, this opinion was based on similarities in the fourth leg observed by the same author) and that M. anceps var. minor is a synonym of M. anceps pauxensis. Rocha (1998) proposed a set of morphological features that would be useful for distinguishing five species previously recorded in Brazil and suggested that M. alius is a possible synonym of M. dubitabilis. Rocha (1998) proposed a set of morphological features that would be useful for distinguishing five species previously recorded in Brazil and suggested that M. alius is a possible synonym of M. dubitabilis. Some questions on the taxonomic status of some species of Microcyclops in America remain unresolved These taxonomic problems may be related to the lack of thorough and rigorous species descriptions. Rocha (1998), Mirabdullayev (1998, 2007), and Mirabdullayev and Urazova (2006) have documented morphological features that are useful for differentiating some species of the genus. They proposed the following morphological features as diagnostic: ornamentation of dorsal margins of prosomites, presence or absence of pores on second endopodite of first leg, ornamentation of the inner margin of basipodite of first leg, ornamentation of caudal ramus and caudal setae, relative lengths of caudal setae, proportions of second endopodite of fourth leg, and general ornamentation of fourth leg
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
