Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species Author Diez, Yander L. 0000-0001-8741-4799 Universidad de Oriente, Biology & Geography Department, Ave. Patricio Lumumba s / n, CP 90500, Santiago de Cuba, Cuba. yanderluis 87 @ gmail. com, yander @ uo. edu. cu; https: // orcid. org / 0000 - 0001 - 8741 - 4799 & Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium yander@uo.edu.cu Author Monnens, Marlies 0000-0002-91331512 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium & marlies. monnens @ uhasselt. be; https: // orcid. org / 0000 - 0002 - 91331512 marlies.monnens@uhasselt.be Author Aguirre, Rosa Isabel 0000-0002-7311-2308 Centro Oriental de Ecosistemas y Biodoversidad (BIOECO). Museo Tomás Romay, Calle Enramadas 601, CP 90100, Santiago de Cuba, Cuba. iaguirrealcolea @ gmail. com; https: // orcid. org / 0000 - 0002 - 7311 - 2308 iaguirrealcolea@gmail.com Author Yurduseven, Rana 0000-0002-2047-5375 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium & rana. yurduseven @ hotmail. com; https: // orcid. org / 0000 - 0002 - 2047 - 5375 rana.yurduseven@hotmail.com Author Jouk, Philippe 0000-0002-6436-2401 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium & philippe. jouk @ kmda. org; https: // orcid. org / 0000 - 0002 - 6436 - 2401 & Royal Zoological Society of Antwerp, Centre for Research & Conservation, Koningin Astridplein 20 - 26, B- 2018 Antwerp, Belgium. University of British Columbia, Departments of Botany and Zoology, 6270 University Blvd., Vancouver, BC, V 6 T 1 Z 4 Canada. philippe.jouk@kmda.org Author Van Steenkiste, Niels W. L. 0000-0002-2676-7862 niels _ van _ steenkiste @ hotmail. com; https: // orcid. org / 0000 - 0002 - 2676 - 7862 niels_van_steenkiste@hotmail.com Author Leander, Brian S. 0000-0003-0798-0470 bleander @ mail. ubc. ca; https: // orcid. org / 0000 - 0003 - 0798 - 0470 bleander@mail.ubc.ca Author Schockaert, Ernest 0000-0003-0666-5604 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium & ernest. schockaert @ uhasselt. be; https: // orcid. org / 0000 - 0003 - 0666 - 5604 ernest.schockaert@uhasselt.be Author Reygel, Patrick 0000-0001-8721-6290 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium & patrick. reygel @ uhasselt. be; https: // orcid. org / 0000 - 0001 - 8721 - 6290 patrick.reygel@uhasselt.be Author Smeets, Karen 0000-0001-9673-8824 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium & karen. smeets @ uhasselt. be; https: // orcid. org / 0000 - 0001 - 9673 - 8824 karen.smeets@uhasselt.be Author Artois, Tom 0000-0002-2491-7273 Hasselt University, Centre for Environmental Sciences, Research Group Zoology: Biodiversity and Toxicology, Universitaire Campus Gebouw D, B- 3590 Diepenbeek, Belgium & tom. artois @ uhasselt. be; https: // orcid. org / 0000 - 0002 - 2491 - 7273 tom.artois@uhasselt.be text Zootaxa 2021 2021-03-23 4948 4 451 500 journal article 7466 10.11646/zootaxa.4948.4.1 ae92fbc8-7dd7-4fcd-a469-9f09c96946f0 1175-5326 4629235 44061E80-81B7-46AF-AD51-9B461C2E2B67 Utelga heinckei ( Attems, 1897 ) Karling, 1954 ( Fig. 20A–C ) Known distribution. Western coast of USA , North Sea, Skagerrak, Irish Sea, Irish Atlantic coast ( Karling 1980 and references therein). Skagerrak ( Willems et al. 2007 ). Galapagos Islands ( Reygel et al. 2011 ). British Columbia , Canada ( Van Steenkiste & Leander 2018 ). New records and material. Observations on live specimens. One whole mount (HU XIII .4.31) from Las Sardinas ( 19°56’24”N ; 76°46’41”W ), Santiago de Cuba , Cuba ( June 21, 2017 ), on Cladophoropsis macromeres covered by silt, 0.7 m deep, salinity 32 ‰. One whole mount (HU XIII .4.32) and one serially-sectioned specimen (HU XIII .4.33) from Mala ( 29°05’0.53”N ; 13°26’59”W ), Lanzarote , Canary Islands ( October 8, 2011 ), medium coarse calcareous sand, from a very steep slope, 48 m deep, salinity 35 ‰. Remarks. The morphology of our specimens corresponds with the description of Karling (1980) . Live specimens about 1 mm long, unpigmented, with a pair of eyes. The proboscis is about 10% of the body length. It shows the typical koinocystidid construction (see Brunet 1972 ; Karling 1980 ), without a juncture sphincter. The pharynx is located in the first body half. The testes lie caudal to the pharynx and ventral to the vitellaria. Two elongated ovaries are situated at the level of the copulatory bulb. Copulatory bulb surrounded by a sheath of strong circular muscles. At the distal end of the copulatory bulb three sclerotised hooks ( Fig. 20A–C ) occur, which differ from each other in size. The largest hook is 13–14 μm long (n = 2) and 5–6 μm wide proximally (n = 2). The smaller hooks are 4–6 μm long ( x̄ = 5 μm; n = 4) and 2–4 μm wide proximally ( x̄ = 3 μm; n = 4).