A key to the identification of agglutinant and monothalamous foraminifera from Brazilian mangroves

Identification keys are essential tools to guarantee higher precision during the taxonomic work. However, such keys are rare for foraminifera and often encompass a restrict group of species from a given geographic region. Thus, the taxonomic identification process usually occurs by visual comparison and by verifying the description of morphological attributes, which requires the previous knowledge of the species before identification. The use of an identification key seeks to help in this crucial step and contribute to the best taxonomic precision, which errors may propagate in the subsequent analyses that are supported by estimations on species richness and abundances. Moreover, it constitutes an extra tool to assist in the training of new researchers. This paper brings an identification key for agglutinant and monothalamous foraminifera from Brazilian mangroves, considering 50 genera and 91 species. AbstrAct Décio Semensatto1*


INtrODUctION
Accurate taxonomic identification is a crucial step in research involving community ecology. Taxonomic errors can propagate along a chain of analysis, when ecological indices, transfer functions and statistical calculations differentiate taxonomic groups, and even over time if a particular work becomes a reference for other researchers to identify species (Wu, 1982;Bortolus, 2008;Payne et al., 2011;Vink et al., 2012). Such consequences can lead to inaccurate or erroneous interpretations of recent and past environmental scenarios and may lead to improper decisions about environmental management when they are based on indicators such as species richness, abundance and diversity. In the case of using indexes such as Shannon (H'), both underestimation and overestimation of rare species significantly impact the value of diversity, as this index applies the logarithm on relative abundance and thus reduces the algebraic difference between dominant species and rare species (Magurran and McGill, 2011).
The use of recent foraminifera as bioindicators has been proposed for several purposes (Scott et  . Although some species are recognized relatively easily, there are cases where only the detailed analysis of morphological attributes will ensure correct identification. Recently, the development of environmental DNA (eDNA) detection tools has pointed to new challenges in the field of taxonomy for foraminiferal species identification and estimating diversity (Pawlowski et al., 2014(Pawlowski et al., , 2016Siemensma et al., 2017). However, in most cases, the identification of foraminifera species is based on the visual comparison between the test and images published in the literature, in addition to the observation of specific morphological characteristics described in detail in some classical references. However, these references do not provide species identification keys, and consulting their content usually requires preidentification of the test in question.
Identification keys are handy tools in training researchers for taxonomy as well as for harmonizing species identification/taxonomic levels. Although certain areas of knowledge widely use these tools, such as Botany, there are few keys available about foraminifera (e.g., Todd and Low, 1981;Clark and Patterson, 1993;Revets, 2005). In this perspective, the present work proposes a key for the identification of Brazilian mangrove agglutinant and monothalamous foraminifera, aiming to contribute to the harmonization between research groups and results in the identification of species, as well as assisting in the training of new researchers.

MAterIAl AND MetHODs
The construction of the identification key started from the creation of a database of occurrence of agglutinant and monothalamous foraminifera species from Brazilian mangroves. Therefore, it includes only articles published in national and international scientific journals, raised from searches in the main platforms of scientific publication available in Periódicos Capes (www. periodicos.capes.gov.br), totaling 19 productions (17 articles, one book chapter and one seminar paper in conference proceedings). The species list reported only for samples collected at mangroves in these papers was compiled, and then the key was constructed to the genus level. For each genus it is also listed the species respectively found in Brazilian mangroves. The construction of the key up to the genus aimed to make it less complex, and the identification of the species should be accompanied by consulting the literature where there are descriptions and images, in addition to the fact that some genera are represented by only one species.
Given that the purpose of this key is to help the researcher correctly identify a species based on the visualization of the test, the key refers to only the morphological attributes that are visible and distinguishable under the stereomicroscope. The organization of the morphological attributes of the species is based on compilation and systematic work of foraminifera that serve as reference for several works (e.g. Ellis and Messina, 1940 et seq.; Closs, 1962;Boltovskoy et al., 1980;Loeblich and Tappan, 1988;Brönnimann et al., 1992;Hayward and Hollis, 1994;Hayward et al., 1999;Scott et al., 2001;Sen Gupta, 2003;Debenay, 2013). In addition to the identification key, species systematics was also organized with hierarchical levels harmonized with the World Foraminifera Database platform (Hayward et al., 2019).

tHe IDeNtIFIcAtION KeY
The key includes 50 genera, which in turn covers 91 species. The key is binary-type, i.e., only two answers are possible and are mutually exclusive. The identification pathways follow steps referenced with numbers. Each step can result in the identification of a genus (so, the identification pathway finishes) or in the indication of the next step to be consulted. In the case of the announced feature coincides with that observed by the researcher, the pathway indicate: "go to 'number'". The entry number in the step is followed by another in parentheses, which indicates which is the previous step to reach that point of the pathway (e.g., '36 (32)': indicates that the researcher has reached step #36 from step #32). Thus, if the identification finishes and does not match the test under observation, it is possible to return to the previous steps and look for alternatives. The images of most of species can be found in plates II, III and III (see Systematics section).
Test without a uniserial or biserial portion -go to 36.
Later part with short and broad chambers -genus Ammoscalaria.

(30). Aperture an interiomarginal arch evaginated at the base of the final chamber -genus -Haplophragmoides.
Other aperture -go to 38.
Test not plan-convex nor concave-convex -go to 45.

(40). Chambers with large pores in the center and edges -genus Discorinopsis.
Chambers without pores -go to 42.
Chambers not extending back at the peripherygo to 43.

cONclUsION
Considering the territorial dimensions of the Brazilian mangroves, the high concentration of results in the states of Sao Paulo and Rio de Janeiro (Table 1), the very limited number of mangroves analyzed on the Northeastern and Northern Brazilian coast, as well as the results from several works that have never been published, the number of species is potentially higher than now recorded. Moreover, new tools for environmental genetic analysis have contributed to revealing a significant abundance of cryptic species present in the environment, which may be taken into account.
In this case, monothalamous species are a particular group rarely reported in the literature. Although in estuarine environments such species are indeed rare in abundance, their occurrence may be underestimated because not all researchers recognize the tests of these species as foraminifera. It can be inferred from the fact that certain species are reported only by a researcher or research group who, having found them at some time, tends to report them again in other works. Besides, it should be considered that some sample preparation procedures potentially eliminate species that attach to substrates, such as sieving (excluding large fragments or particles where individuals may be attached) and flotation (decantation of denser particles with attached tests).
In addition to these factors, 28 genera were reported at some point without species identification (Table 1) In addition to the possibility that these genera include species not yet described in the literature, it may emphasize the potential impact that species omission can have on ecological indices (e.g., diversity and evenness), as well as for comparison between assemblages (similarity indices), which are strongly influenced by taxonomic accuracy. Additionally, the synonyms may draw attention, since some same genera and species are reported differently in the literature. It is the case, for example, of the genus Entzia, the accepted synonym for the genus Jadammina, which in its turn has moved to the status of "not accepted" on the platform maintained by Hayward