A study on the etymology of the scientific names given to planarians (Platyhelminthes, Tricladida) by Ernest Marcus’ school

Leading zoologist and taxonomist Ernest Marcus (1893‐1968) and his school described numerous new invertebrate taxa, including planarians, or triclads (Platyhelminthes). These authors rarely provided the etymology of names for the new taxa. In this paper, the etymology of 149 names of genera and specific epithets of planarians lacking etymology (or honoring people) is investigated. The etymology of most names was retrieved from original descriptive papers and from Eudóxia Maria Froehlich’s recollections, a fellow of Marcus’ school. It was discovered that the names were usually freely derived from words of the language spoken in the country where the species was found. Some names were motivated by an aspect of the biology of the species. Other names honored people or are arbitrary. The etymology of 19 names could not be retrieved and are only suggested. The origin of another 19 names could not be discovered, nor even their meaning. Knowing the etymology makes it easier to memorize a name and it is a way to preserve the historical and emotional aspects of the authors. Through the retrieved etymologies, the personality of Marcus can also be glimpsed. Key-Words. Classification; Nomenclature; Geoplana; Historiography; Taxonomy.


Roots may be formed in several ways
Foucault, 1994, The order of things From the dawn of history, humans were already taxonomists. By distinguishing linguistically food from non-food, potential predators from non-predators, they increased survival chances (Dunn & Davison, 1968;Raven et al., 1971). It was Linnaeus's binomial nomenclature in the 18 th century that made species names universal. Over 1.87 million species have received a scientific name, of which 1.28 are animals (http://www.catalogueoflife.org/col, access: 25/07/2020). Estimates point to about 7.77 million animal species on Earth (Mora et al., 2011), 76% of them not yet described. New species need a new name. For animals, the International Code of Zoological Nomenclature, or the Code (ICZN, 1999) regulates nomenclatural acts and etymological rules of new names at ranks between subspecies and family level. The origin of a name given to a taxon is called derivation or etymology. Coining a name is probably the only place for taxonomists to express themselves freely and creatively. The Code provides support for that: "A name may be a word in or derived from Latin, Greek or any other language (even one with no alphabet) or be formed from such a word. It may be an arbitrary combination of letters providing this is formed to be used as a word" (Art. 11.3, ICZN, 1999). Authors are not obliged to provide the etymology of new names, since it is only a recommendation (Recommendation 25C of ICZN, 1999). The same is true for Botanists and the International Code of Nomenclature for algae, fungi, and plants (Recommendation 60H.1, Turland et al., 2018), but not for bacteriologists, who must give the derivation of a new name (Rule 27b, Parker et al., 2019). Nevertheless, some taxonomic journals expressly require from authors to give the etymology of new names (e.g., European Journal of taxonomy, https://europeanjournaloftaxonomy.eu/index.php/ejt; Zookeys, https://zookeys.pensoft.net; Zoologia https:// www.scielo.br/revistas/zool/iinstruc.htm; access: 03/08/2020) or to follow the rules and recommendations of the Code (e.g., this journal).
Authors of new names usually evoke a biological aspect of the species named, such as mor-phological, behavioral or the geographical origin of the species. Authors may also honor someone deserving respect, or they simply give humorous or peculiar names which have nothing to do with the species being named (Ohl, 2018).
For taxonomists, names based on a biological aspect may make the name easy to memorize. For historiographers, etymology of names may help discover aspects of the author giving the name. However, in the past, taxonomists did not always provide the etymology of the new names of animals. This is the case of the school of Prof. Ernest Marcus (1893Marcus ( -1968 for the free-living flatworms (Platyhelminthes) they studied.
German-born, Marcus was Zoologist and professor at the Institute of Zoology at the University of Berlin. Further biographical accounts are found in Mendes (1994), Carbayo et al. (2009) andWinston (2002). In 1936 Marcus and his wife, Eveline du Bois Raymond-Marcus (1901-1990 moved to São Paulo, Brazil, where they wrote a "monumental monographic work of South American micro-and macroturbellarians" (Rieger, 1998). Between 1936 and 1968 they published 162 papers in Brazil on several animal Phyla (Mendes, 1994). Marcus mentored prominent zoologists (Winston, 2002;Carbayo et al., 2009). He also founded a Brazil-based productive school of morphology and systematics of free-living flatworms, composed of Eveline du Bois-Reymond Marcus, Claudio Gilberto Froehlich, Eudóxia Maria Froehlich (1928-2015, Diva Diniz Corrêa (1918Corrêa ( -1993 and Maria Elisa Quissak Martins. Between 1946 and1978, Marcus's school published several papers with the description of numerous species and genera of planarians, or triclads (Tricladida, Platyhelminthes), besides further works on additional flatworms and other phyla. The etymology of the new names was rarely revealed by them. The purpose of the present work is to investigate the etymology of triclad names given by Marcus' school.

MATERIAL AND METHODS
We circumscribed the reporting period to 1946 being the first year that a paper on triclads was published, and 1978 the last paper before etymology of new names was regularly provided. We produced a list of generic and specific epithets of planarians given by Marcus' school, from the species and genera compiled in Carbayo et al. (2009), Carbayo & Froehlich (2008 and Tyler et al. (2006Tyler et al. ( -2013 lacking etymology. In this list we maintained names of species honoring personalities as a contribution to the historiography. We read the papers with original descriptions in search of clues of the etymology. We explored Eudóxia's recollections as she lived with Marcus and Eveline since the late 1940 until Marcuses' decease. We recorded her memories about the etymology in two situations: intermittently when the issue arose during the meetings with FC over the last ten years of her life, and on two formal scheduled interviews with PDS. Subsequently, we checked the meaning of the epithets in Quechua, English, Kukama-Kukamiria, Latin, Portuguese, Spanish, and Tupi dictionaries and lexicons (Ajacopa, 2007;Lewis & Short, 1879;Brown, 1956;Bueno, 1998;Collins, 2014;Gregório, 1980;Houaiss, 2001;RAE, 2020;Tibiriçá, 1984;Vallejos & Amías, 2015). Claudio Gilberto Froehlich checked the etymologies of a preliminary glossary and provided the derivation of some epithets.
We assembled the names and their etymologies in a glossary, with each name fitting one of four categories according to the motivation: names derived from characteristics of the species (including size, shape, color, morphology, habitat, locality); commemorative names; arbitrary names, and names with putative etymology, the latter cases indicated with 'prob' in the glossary. For each entry of the glossary, we provided the original species name or the genus name, authority, year of publication, etymology, and the country where the taxon (species or genus) was originally found. We omitted from the glossary epithets from which both their meaning and motivation remain elusive. Martins (1). This assignment is not a fully accurate picture of authorship, for Marcus signed alone in papers but his wife's coauthorship is expressed clearly in relevant taxonomic papers (e.g., Marcus, 1947Marcus, , 1951; see also Edmunds, 1991).
A scientific name depicts the creative pinnacle of a taxonomic work, and the etymological meaning may be of historical or emotional interest (Ohl, 2018). Independently from requirements of the nomenclatural codes, we advocate the disclosure of the etymology of new names at the time of proposing a new taxon. Otherwise, the meaning of a name may well be lost in forgotten memories.
Through this study, we hope to contribute to preserving these historical and creative aspects of Ernest Marcus -one amongst the most prominent zoologists of the 20 th century (Sawaya, 1970;Mendes, 1994;Zarur, 1994) -and those of his school. and for his help with some English-derived epithets. Claudio Gilberto Froehlich (University of São Paulo) is also thanked for sharing his memories on the etymology of some names. Rodrigo H. Willemart (University of São Paulo) and Domingo Lago-Barcia are sincerely thanked for their comments on a draft of this article. FC has financial support of FAPESP (proc. 2019/12357-7). We extend our thanks to an anonymous reviewer for her/his constructive comments and suggestions. This article is dedicated to the memory of Prof. Sérgio Antônio Vanin, who also reviewed the article.

AUTHORS' CONTRIBUTIONS
PDJ: Methodology, Data analysis, Writing, Review and Editing. EMF: Data analysis, Writing. FC: Conceptualization, Methodology, Data analysis, Supervision, Writing, Review and Editing. All the authors actively participated in the discussion of the results, PDJ and FC reviewed and approved the final version of the paper.

CONFLICTS OF INTEREST
Authors declare there are no conflicts of interest.

APPENDIX Glossary
For each entry of the glossary, there are provided the original species or genus name, authority, year of publication, etymology, and the country where the taxon (species or genus) was originally found. Epithets from which both their meaning and motivation remain elusive are omitted (see text). Froehlich, 1959. Biology. From the Tupi apeva, or apeba, meaning flattened and widened. It is a reference to the shape of the body: "large, broad and flat" (Froehlich, C.G., 1959). Species from Brazil. arndti. Dugesia arndti Marcus, 1946. Posthumous homage to the Zoologist Walter Arndt, from the Zoological Museum Berlin (Marcus, 1946). Species from Brazil. assu. Geoplana assu Froehlich, 1959. Biology. Tupi word meaning big and thick. It is a reference to the body size of the species: "A large, flat and broad species" (Froehlich, C.G., 1959). Species from Brazil. astraea. Geoplana astraea Marcus, 1951. Biology. From the Latin astr-, astro-(star, star system, constellation. A reference to the resemblance of the dorsum the species to a starry night: "dorsum […] black […] with clear halos" (Marcus, 1951). Species from Brazil. astrocheta. Dugesia astrocheta Marcus, 1953. Biology. A combination of the Latin astro-(star) and the Greek chaite (long hair). A reference to the aspect of the preserved species resembling a star with radiating setae: "In all the clarified worms the gut contains masses of spongillid tissues and needles" (Marcus, 1953). Species from the Republic of the Congo. aymara. Geoplana aymara du Bois-Reymond Marcus, 1951. Arbitrary. From Spanish word aimará, meaning a South American Indian person from highland Peru.

apeva. Geoplana apeva
Species from Peru. beckeri. Geoplana beckeri Froehlich, 1959. Homage to Mr. Johann Becker, Entomologist at the Museu Nacional do Rio de Janeiro, who collected and donated the type material. Species from Brazil. bilix. Choeradoplana bilix Marcus, 1951. Biology. From Latin bilis, is, meaning bile. A reference to the yellowish color of the dorsum: "The dorsum is yellowish, with two wide grey-brownish stripes" (Marcus, 1951). Species from Brazil. caapora. Geoplana caapora Froehlich, 1957. Biology. Tupi word meaning inhabitant of the woods. A reference to the habitat of the species. Species from Brazil. cafusa. Geoplana cafusa Froehlich, 1956. Biology. From the Portuguese cafuso, or cafuzo, meaning a person of mixed African and Amerindian ancestry. A reference to the brownish color of the dorsum: "The dorsum is black, which fades to brown-grayish towards the sides of the body" (Froehlich, C.G., 1956a). Species from Brazil. caissara. Geoplana caissara Froehlich, 1955 Corrêa, 1947. A homage to João de Paiva Carvalho, who worked at the Instituto de Pesca Marítima and donated the type specimens (Corrêa, 1947). An Asian species introduced into Brazil. cassula. Geoplana cassula Froehlich, 1955. Biology. From the Portuguese caçula, meaning younger brother. A reference to the small body size: "Small worms with strongly convex dorsum" (Froehlich, E.M., 1955 Froehlich, 1955. Biology. A free composition from the Tupi words tim, meaning snout, and mbé, meaning flattened. A reference to the pointed shape of the anterior extremity of the body: "the body narrows progressively until the anterior extremity of the body" (Froehlich, E.M., 1955). Species from Brazil. chita. Geoplana chita Froehlich, 1956. Biology. From the Portuguese chita, meaning colored printed cotton fabric of little value. A reference to the dorsal color of the body: "Parenchyma whitish […], dorsally seen as abundant circular or elliptical areas with various sizes […]" (Froehlich, C.G., 1956b). Species from Brazil. chiuna. Geoplana chiuna Froehlich, 1955. Biology. From the Tupi chiuna, meaning black nose. A reference to the black anterior extremity of the body: "The anterior extremity is black" (Froehlich, E.M., 1955). Species from Brazil. chulpa. Geoplana chulpa du Bois-Reymond Marcus, 1951. Prob. from the Aymara word chullpa, meaning a type of Peruvian funerary tower or ancient sarcophagus.
Species from Peru. conyum. Othelosoma conyum Marcus, 1953. Prob. from the English word cony, a name for the ungulate Syrian rock hyrax, in reference to the color pattern of the back.