Dataset of morphological characters for taxonomic and phylogenetic studies on the isopod family Macrostylidae Hansen, 1916 for the computer software DELTA (Dallwitz 1980, Dallwitz et al. 2010). History: This datased has been compiled since 2012 by Torben Riehl and served as basis for the description of numerous species of Macrostylidae (Riehl et al. 2012, Riehl & Kaiser 2012, Riehl & Brandt 2013, Bober et al. 2018, Kniesz et al. 2018, Riehl & DeSmet 2020, Riehl & Kühn 2020) as well as (intermittendly) the family Urstylidae (Riehl et al. 2014). After this initial exploratory phase, the dataset was stripped down of any characters which turned out to be without value for taxonomic or phylogenetic purposes, ambiguous or inconsistent. Also, all data related to the Urstylidae but unimportant for the Macrostylidae have been removed. As it is now published, this dataset served as foundation for the description of Macrostylis papandreas (Senckenberg Ocean Species Alliance 2024). Further information: Character states were coded using the logical basis described by Sereno (2007). In many cases, instructions how to measure and interpret characters and character states are recorded in the "Notes" tab. Acknowledgements: This dataset has been grown over many years, first with support from mentors and supervisors, later with temporary support of bachelor, master and PhD students who accumulated data through their studies. Torben Riehl would like to thank Angelika Brandt, George D.F. Wilson and Jörundur Svavarsson for their mentorship, and Nele Johannsen, Mona Kühn, Katharina Kniesz, Katharina Kohlenbach, Jona Silberberg, Christian Zeitz, Simon Bober and Bart DeSmet for their additions to the database. References: Bober S, Riehl T, Henne S, Brandt A (2018) New Macrostylidae (Isopoda) from the Northwest Pacific Basin described by means of integrative taxonomy with reference to geographical barriers in the abyss. Zoological Journal of the Linnean Society 182: 549–603. https://doi.org/10.1093/zoolinnean/zlx042 Dallwitz MJ (1980) A general system for coding taxonomic descriptions. Taxon 29: 41–46. Dallwitz MJ, Paine TA, Zurcher EJ (2010) User’s guide to the DELTA editor. http://delta-intkey.com. Available from: http://delta-intkey.com. Kniesz K, Brandt A, Riehl T (2018) Peritrich ciliate epibionts on the new hadal isopod species Macrostylis marionae from the Puerto Rico Trench as an indicator for sex-specific behaviour. Deep-Sea Research Part II: Topical Studies in Oceanography 148: 105–129. https://doi.org/10.1016/j.dsr2.2017.10.007 Riehl T, Kaiser S (2012) Conquered from the deep sea? A new deep-sea isopod species from the Antarctic shelf shows pattern of recent colonization. PLoS ONE 7: e49354. https://doi.org/10.1371/journal.pone.0049354 Riehl T, Brandt A (2013) Southern Ocean Macrostylidae reviewed with a key to the species and new descriptions from Maud Rise. Zootaxa 3692: 160–203. http://dx.doi.org/10.11646/zootaxa.3692.1.10 Riehl T, De Smet B (2020) Macrostylis metallicola spec. nov. — An isopod with geographically clustered genetic variability from a polymetallic-nodule area in the Clarion-Clipperton Fracture Zone. PeerJ 8: 1–44. https://doi.org/10.7717/peerj.8621 Riehl T, Kühn MAL (2020) Uniting what belongs together — reevaluation of the isopod species Macrostylis grandis and M. ovata using ontogenetic, morphological and genetic evidence. Progress in Oceanography 181: 102238. https://doi.org/10.1016/j.pocean.2019.102238 Riehl T, Wilson GDF, Hessler RR (2012) New Macrostylidae Hansen, 1916 (Crustacea: Isopoda) from the Gay Head-Bermuda transect with special consideration of sexual dimorphism. Zootaxa 3277: 1–26. https://doi.org/10.11646/zootaxa.3277.1.1 Riehl T, Wilson GDF, Malyutina MV (2014) Urstylidae – A new family of deep-sea isopods and its phylogenetic implications. Zoological Journal of the Linnean Society 170: 245–296. https://doi.org/10.1111/zoj.12104 Senckenberg Ocean Species Alliance, Brandt A, Chen C, Engel L, Esquete P, Horton T, Jazdzewska A, Johannsen N, Kaiser S, Kihara TC, Kniesz K, Knauber H, Landschoff J, Lörz A-N, Machado FM, Martínez-Muñoz CA, Riehl T, Serpell-Stevens A, Sigwart JD, Tandberg A-H, Tato R, Tsuda M, Vončina K, Watanabe HK, Wenz C, Williams JD (in preparation) Ocean Species Notes 1-12 - taxonomic contributions to marine invertebrate discovery. Biodiversity Data Journal. Sereno PC (2007) Logical basis for morphological characters in phylogenetics. Cladistics 23: 565–587. https://doi.org/10.1111/j.1096-0031.2007.00161.x