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Sabulirhynchus axi Artois & Schockaert, 2000 Fig. 3A–D Material examined PANAMA • 5 whole mounts; Pacific Ocean, Isla Iguana; 7°37′46″ N, 79°59′49″ W; depth 6 m; 6 Mar. 2016; subtidal, coarse sand; HU XIX.2.01–XIX.2.05 • 2 whole mounts; same collection data as preceding; 7°38′06″ N, 79°59′48″ W; depth 10 m; subtidal, coarse sand mixed with small rocks and covered with organic matter; HU XIX.2.06–XIX.2.07. Distribution Bahia Academy, Santa Cruz, Galapagos Islands (Artois & Schockaert, 2000). Remarks The specimens collected in Panama are morphologically similar to those from the Galapagos. The prostatic stylet type III (Fig. 3A–D) is 46–76 µm long (x = 62 µm; n = 7) and 10–31 µm wide (x = 21 µm; n = 7). A feature of the female system, not mentioned by Artois & Schockaert (2000), is the presence of a proximal, apparently sclerotised cap in the seminal receptacle.

Sabulirhynchus ibarrae sp. nov. urn:lsid:zoobank.org:act: 1EA7110C-D687-42BB-87A7-1259A24E4E0E Figs 3E–F, 4 Diagnosis Species of Sabulirhynchus Artois & Schockaert, 2000 with a very long proboscis, representing 40% of the body length. Prostatic stylet type III plate-shaped, ~53 µm long, proximally tubular and with a ridge at its midlength. Seminal reservoir exhibits a proximal apparently sclerotised cap. Etymology Species named after the late Dr María Elena Ibarra Martín (Marine Research Centre, Havana University, Cuba), head of the MRC for more than 25 years, who indefatigably championed the protection of oceans. Awarded with the National Prize of Environmental Sciences of Cuba in 2007. The Research Group of Marine Ecology of Universidad de Oriente carries her name. Material examined Holotype CUBA • 1 whole mount; Santiago de Cuba, Siboney; 19°57′34″ N, 75°42′07″ W; 7 Feb. 2019; depth 3 m; sublittoral, coarse-grained sand, salinity 34 ‰; https://id.luomus.fi/KV.700; FMNH. Other material CUBA • 1 whole mount; same collection data as for holotype; photographs of live specimens available; HU XIX.2.08. Description The specimens are unpigmented (Fig. 4A), ~ 1.5 mm long. The proboscis (Fig. 4A–B: pr) attains 40% of the body length. Caudally to the proboscis there is a pair of eyes (Fig. 4A–B: e). The pharynx is at the midbody (Fig. 4A–B: ph). A testis (Fig. 4A–B: t) is located beside the pharynx and occupies the middle third of the body. The prostatic stylet type III (Figs 3E–F, 4C; 4A–B, 4D: ps3) is plate-shaped, 49–56 µm long (x = 53 µm; n = 2), and 20–21 µm wide proximally; it is proximally tubular and exhibits a ridge at its midlength. The vitellarium (Fig. 4A–B: vi) runs from the posterior end of the proboscis to the caudal body end. The oval ovary (Fig. 4B, D–E: ov) has the oocytes organised in a row. The female bursa (Fig. 4A–B, D: b) is positioned caudally to the male atrial organs. The spindle-shaped seminal receptacle (Fig. 4B, D–E: sr) is filled with sperm and proximally exhibits a seemingly sclerotised cap (Fig. 4D–E: sc). The gonopore opens at 80% (Fig. 4B: cg). Remarks Until now, the genus Sabulirhynchus included a single species: Sabulirhynchus axi. Sabulirhynchus ibarrae sp. nov. and S. axi share the diagnostic features of the genus: lack of accessory glandular organ in the male system, a plate-shaped prostatic stylet type III, and a pyriform seminal receptacle in the female atrium (Artois & Schockaert 2000). Considering the newly analysed material of both species, we add to the diagnosis of Sabulirhynchus the presence of a proximal, apparently sclerotised cap in the seminal receptacle. This feature is easily recognisable in live specimens; however, we did not distinguish it on the whole mounts. Therefore, the sclerotised nature of this structure is questionable. The prostatic stylet is similar in length in both species, 52–63 µm long in S. axi (population from the Galapagos) and ~53 µm in S. ibarrae sp. nov. However, it is more variable in the population of S. axi from Panama (46–76 µm long). The stylet of S. axi is a simple plate, distally turned backward (Artois & Schockaert 2000), whereas it is straight, proximally tubular, and with a ridge at its midlength in S. ibarrae sp. nov. These differences in stylet morphology warrant the status of a new species., Published as part of Diez, Yander L., Sanjuan, Claudia, Monnens, Marlies & Artois, Tom, 2023, New species of Polycystididae (Platyhelminthes: Kalyptorhynchia) from Cuba and the Pacific coast of Panama, pp. 67-86 in European Journal of Taxonomy 856 on pages 78-80, DOI: 10.5852/ejt.2023.856.2029, http://zenodo.org/record/7554565, {"references":["Artois T. & Schockaert E. 2000. Interstitial fauna of the Galapagos: Typhlopolycystidinae (Platyhelminthes, Polycystididae). Tropical Zoology 13: 141 - 158. https: // doi. org / 10.1080 / 03946975.2000.10531128","Evdonin L. A. 1977. Monograph of the Turbellaria Kalyptorhynchia in the fauna of the USSR and adjacent areas [in Russian]. Fauna of the USSR 115: 1 - 400."]}

Phonorhynchoides lalanai sp. nov. urn:lsid:zoobank.org:act: 94BB22AE-7C11-4ECB-A344-B8ACFB01CF28 Figs 1C, I–J, 2D, G, Table 2 Phonorhynchoides sp. in Leasi et al. 2018: 1–12. Diagnosis Species of Phonorhynchoides Beklemischev, 1927 with a prostatic stylet type IV ~114 µm long, proximally ~9 µm, narrowing to 5 µm wide distally; it is twisted in the middle. Accessory stylet type IV 105–106 µm long, narrowing from 4–5 µm wide proximally to 2 µm wide distally; slightly curved in the proximal half. Etymology Species named after the late Dr Rogelio Lalana (Marine Research Centre, Havana University, Cuba), prominent Cuban marine researcher, awarded with the National Prize of Marine Sciences of Cuba in 2012, for his outstanding contribution to the knowledge of marine invertebrates, mainly crustaceans. Material examined Holotype CUBA • 1 whole mount; Santiago de Cuba, Bueycabón; 19°57′38″ N, 75°57′28″ W; 6 Feb 2018; depth 0.5 m; sublitoral, fine-grained sand rich in organic matter, salinity 33 ‰; https://id.luomus.fi/KV.699; FMNH. Other material PANAMA • 2 whole mounts; Pacific Ocean, Isla Iguana; 07°38′06″ N, 79°59′48″ W; 6 Mar. 2016; depth 10 m; sublittoral, coarse sand with gravel, covered with organic matter; HU XIX.1.49–XIX.1.50. Description The specimens are unpigmented (Fig. 2D), ~ 1 mm long. The proboscis (Figs 1C, 2D: pr) is less than 10% of the body length. A pair of eyes is located just behind the pharynx (Figs 1C, 2D: e). The pharynx (Figs 1C, 2D: ph) is positioned in the anterior body half. A pair of testes (Fig. 1C: t) is located posterior to the pharynx. The prostatic stylet type IV (Figs 1C, 2G: ps4, 1I) is 110–120 µm long (x = 114 µm; n = 3) and narrows from a width of 8–11 µm proximally (x = 9 µm; n = 3) to 5 µm distally (n = 3); the distal end is rounded. At about midway, the prostatic stylet is twisted. The accessory stylet type IV (Figs 1C, 2G: as4, 1J) is 105–106 µm long (n = 3), slightly curved in the proximal half, and narrows from 4–5 µm wide proximally (n = 3) to 2 µm wide distally (n = 3); the distal end is oblique and sharp. The vitellaria (Fig. 1C: vi) run from just behind the pharynx to the caudal body end. The female bursa (Fig. 1C: b) is located beside the stylets; it is muscular but not bipartite. The ovaries (Fig. 1C: ov) are located rostrally to the stylets; they are more or less kidney-shaped, with the oocytes organised in a row; the oocytes distally increase in diameter. Remarks Phonorhynchoides lalanai sp. nov. exhibits the diagnostic features of Phonorhynchoides: the prostatic stylet type IV is larger than the accessory stylet type IV, and the female bursa is muscular but not bipartite (Willems et al. 2017). The prostatic stylet of P. lalanai sp. nov. is twisted at the end of its proximal half, while this structure is never twisted in the other six known species of the genus. For comparison, the prostatic stylet is undulated in P. carinostylis Ax & Armonies, 1987 and P. gondwanae Willems & Artois in Willems et al., 2017, corkscrew-shaped in the middle in P. somaliensis Schockaert, 1971, and almost straight in P. flagellatus Beklemischev, 1927, P. japonicus Ax, 2008, and P. minor Diez, Sanjuan, Reygel & Artois in Diez et al., 2018b (for details see Willems et al. 2017; Diez et al. 2018b). Furthermore, the prostatic stylet carries ornamentations in P. carinostylis (spiral ridge over the whole length) and P. japonicus (thickened proximally and short spiral ridge), which are missing in P. lalanai. In P. lalanai, the prostatic stylet is distally rounded, differing from that in P. minor (terminally oblique) and the other species (sharp tip). The prostatic stylet of P. lalanai. (~114 µm) is considerably longer than that of P. minor (53–58 µm), but shorter than that in the other species (see Table 2). The accessory stylet type IV of P. lalanai sp. nov. ends in an oblique tip, while it ends in a pointed tip in all other species of Phonorhynchoides. The accessory stylet of the new species (105–106 µm) is smaller than that of P. gondwanae and P. japonicus, but larger than that of the other species (see Table 2). The length proportion between the accessory stylet type IV and the prostatic stylet type IV is larger in the Caribbean species (P. lalanai 88–95%, P. minor 78–85%) than in their known congeners (Willems et al. 2017; Diez et al. 2018b) (see Table 2). Indeed, it is characteristic of P. lalanai and P. minor that the prostatic stylet and accessory stylet are similar in length. The distinct morphology of the sclerotised stylets, previously discussed, warrants the status of P. lalanai as a new species.

Djeziraia adriani sp. nov. urn:lsid:zoobank.org:act: 39C06707-C4B5-4640-9B0D-7CAC9784D00E Figs 1B, G–H, 2B–C, F Diagnosis Species of Djeziraia Schockaert, 1971 with paired seminal vesicles. Gonads and atrial organs located caudally in the body. Prostatic stylet type IV 92–93 µm long, curved, S-shaped in live animals. Etymology Species named after Dr Adrian David Trapero Quintana (Havana University, Cuba), specialist in freshwater ecology and the taxonomy of Odonata. Material examined Holotype CUBA • 1 whole mount; Santiago de Cuba, Sardinero; 19°57′42″ N, 75°47′00″ W; 18 Mar. 2021; intertidal, mangrove area surrounding the mouth of Río Sardinero, 80 m from the beach, sample of sediment with rotten leaves and branches, salinity 32 ‰; https://id.luomus.fi/KV.698; FMNH. Other material CUBA • 2 whole mounts; same collection data as for holotype; photographs of live specimens available; HU XIX.1.47–XIX.1.48. Description The live specimens are unpigmented (Fig. 2B–C), 0.8–0.9 mm long, measured on whole mounts. A pair of well-differentiated bristles (Figs 1B, 2B: bt) is located at the sides of the proboscis pore. The proboscis (Figs 1B, 2B: pr) represents less than 10% of the body length. A pair of eyes (Figs 1B, 2B: e) is located just behind the proboscis. The pharynx (Figs 1B, 2B: ph) is positioned in the anterior body half. The gonads and atrial organs occur in the caudal body half (Figs 1B, 2C). The testes are located rostrally to the ovaries. The paired seminal vesicles (Figs 1B, 2F: sv) open through a single ejaculatory duct into the copulatory bulb. The ejaculatory duct is surrounded by the prostate vesicle type IV (Figs 1B, 2F: pv4). The cell bodies of the prostatic glands are extracapsular and enter the copulatory bulb proximally. The prostatic stylet type IV (Figs 1B, 2C, F: ps4; 1G–H) is tubular and 92–93 µm long (n = 3). The proximal funnel-shaped part of the stylet is 9–10 µm wide, and it tapers to a distally rounded tip, subdistally 4 µm wide; the aperture is completely terminal. Oocytes are organised in a row and proximally diminish in diameter. The vitellaria run laterally, from the pharynx almost to the caudal body end. The female bursa is located next to the stylet. The common gonopore opens at 90%. Remarks Djeziraia adriani sp. nov. exhibits most diagnostic features of Djeziraia: the proboscis is very small, less than 10% of the body length; the atrial organs are located in the caudal body half; the prostate vesicle is interposed; and there is a single prostatic stylet type IV in the male atrium (cf. the other representatives of Phonorhynchoidinae Tessens, Janssen & Artois, 2014 with two or three stylets) (see Schockaert 1971; Artois & Schockaert 2001). A striking feature of the new species is the fact that there are two seminal vesicles, while there is only one in its congeners: Djeziraia euxinica (Mack-Fira, 1971) sensu Schockaert 1982, D. incana Artois & Schockaert, 2001, D. longystila Noreña, Damborenea, Faubel & Brusa, 2007, and D. pardii Schockaert, 1971. Furthermore, the presence of a diverticulum at the bursal stalk (Schockaert 1971) was not observed in our live specimens. Despite these differences, the overall morphology of the new species largely corresponds to what is described for Djeziraia, and we therefore provisionally include it in this genus. Molecular phylogenetic work may prove useful to confirm this preliminary classification. The prostatic stylet type IV of all species of Djeziraia is a simple tube: it is slender and very long (D. longystila and D. incana) or short and straight (D. euxinica and D. pardii). In D. euxinica, the stylet is longitudinally striated and ends in a small hook. The general morphology of the prostatic stylet of D. adriani sp. nov. is comparable to that of D. longystila and D. incana. However, it is S-shaped in live specimens of the new species. Furthermore, the prostatic stylet of D. adriani (92–93 µm) is shorter than that of D. longystila (~275 µm; Noreña et al. 2007), D. incana (~179 µm, 295 µm in one specimen; Artois & Schockaert 2001), and D. euxinica (105–120 µm; Mac-Fira 1971; Artois & Schockaert 2001), and larger than that of D. pardii (~84 µm; Schockaert 1971). Both the presence of paired seminal vesicles and the morphology of the stylet support the validity of the new species, Djeziraia adriani sp. nov., Published as part of Diez, Yander L., Sanjuan, Claudia, Monnens, Marlies & Artois, Tom, 2023, New species of Polycystididae (Platyhelminthes: Kalyptorhynchia) from Cuba and the Pacific coast of Panama, pp. 67-86 in European Journal of Taxonomy 856 on pages 72-74, DOI: 10.5852/ejt.2023.856.2029, http://zenodo.org/record/7554565, {"references":["Tessens B., Janssen T. & Artois T. 2014. Molecular phylogeny of Kalyptorhynchia (Rhabdocoela, Platyhelminthes) inferred from ribosomal sequence data. Zoologica Scripta 43 (5): 519 - 530. https: // doi. org / 10.1111 / zsc. 12066","Schockaert E. R. 1971. Turbellaria from Somalia 1. Kalyptorhynchia (part 1). Monitore Zoologico Italiano 4 (5): 101 - 122.","Artois T. & Schockaert E. 2001. Interstitial fauna of the Galapagos: Duplacrorhynchinae, Macrorhynchinae, Polycystidinae, Gyratricinae (Platyhelminthes, Polycystididae). Tropical Zoology 14: 63 - 85. https: // doi. org / 10.1080 / 03946975.2001.10531143","Mack-Fira V. 1971. Deux turbellaries nouveaux de la Mer Noire. Revue romaine de Biologie Serie de Zoologie 16 (4): 233 - 240.","Schockaert E. R. 1982. Turbellaria from Somalia 2. Kalyptorhynchia (part 2). Monitore Zoologico Italiano 18 (2): 81 - 96.","Norena C., Damborenea C., Faubel A. & Brusa F. 2007. Composition of meiobenthonic Platyhelminthes from brackish environments of the Galician and Cantabrian coasts of Spain with the description of a new species of Djeziraia (Polycystididae, Kalyptorhynchia). Journal of Natural History 41 (29 - 32): 1989 - 2005. https: // doi. org / 10.1080 / 00222930701526055"]}

Sabulirhynchus axi Artois & Schockaert, 2000 Fig. 3A–D Material examined PANAMA • 5 whole mounts; Pacific Ocean, Isla Iguana; 7°37′46″ N, 79°59′49″ W; depth 6 m; 6 Mar. 2016; subtidal, coarse sand; HU XIX.2.01–XIX.2.05 • 2 whole mounts; same collection data as preceding; 7°38′06″ N, 79°59′48″ W; depth 10 m; subtidal, coarse sand mixed with small rocks and covered with organic matter; HU XIX.2.06–XIX.2.07. Distribution Bahia Academy, Santa Cruz, Galapagos Islands (Artois & Schockaert, 2000). Remarks The specimens collected in Panama are morphologically similar to those from the Galapagos. The prostatic stylet type III (Fig. 3A–D) is 46–76 µm long (x = 62 µm; n = 7) and 10–31 µm wide (x = 21 µm; n = 7). A feature of the female system, not mentioned by Artois & Schockaert (2000), is the presence of a proximal, apparently sclerotised cap in the seminal receptacle., Published as part of Diez, Yander L., Sanjuan, Claudia, Monnens, Marlies & Artois, Tom, 2023, New species of Polycystididae (Platyhelminthes: Kalyptorhynchia) from Cuba and the Pacific coast of Panama, pp. 67-86 in European Journal of Taxonomy 856 on pages 77-78, DOI: 10.5852/ejt.2023.856.2029, http://zenodo.org/record/7554565, {"references":["Artois T. & Schockaert E. 2000. Interstitial fauna of the Galapagos: Typhlopolycystidinae (Platyhelminthes, Polycystididae). Tropical Zoology 13: 141 - 158. https: // doi. org / 10.1080 / 03946975.2000.10531128","Evdonin L. A. 1977. Monograph of the Turbellaria Kalyptorhynchia in the fauna of the USSR and adjacent areas [in Russian]. Fauna of the USSR 115: 1 - 400."]}

Brachyrhynchoides ortizi sp. nov. urn:lsid:zoobank.org:act: 774F2120-7B24-4F35-82EE-C46D93D9D9A7 Figs 1A, D–F, 2A, E, Table 1 Diagnosis Species of Brachyrhynchoides Artois & Schockaert, 2013 with the prostatic stylet type IV tubular, ~70 µm long, ~15 µm wide proximally, distally slightly narrower; terminal aperture oblique. Accessory stylet I tubular, 70 µm long; accessory stylet II needle-shaped, 59 µm long. Etymology Species named after Dr Manuel Ortiz (Marine Research Centre, Havana University, Cuba), prominent Cuban marine researcher, for his outstanding contribution to the knowledge of marine invertebrates, mainly crustaceans. Material examined Holotype CUBA • 1 whole mount; Santiago de Cuba, Siboney; 19°57′34″ N, 75°42′07″ W; 7 Feb 2019; depth 2 m; sublittoral, coarse-grained sand with fragments of calcareous algae, salinity 34 ‰; https://id.luomus.fi/KV.697; FMNH. Other material CUBA • 1 whole mount; same collection data as for holotype; photographs of live specimens available; HU XIX.1.46. Description The live specimens are unpigmented (Fig. 2A), ~ 1.5 mm long. The proboscis (Figs 1A, 2A: pr) measures less than 10% of the body length. A pair of eyes (Figs 1A, 2A: e) is located caudally to the proboscis. The pharynx (Figs 1A, 2A: ph) is located in the anterior body half. A pair of testes (Figs 1A, 2A: t) is located caudally to the pharynx. The prostatic stylet type IV (Figs 1A, 2A, 2E: ps4; 1D) is tubular, 68–71 µm long (x = 70 µm; n = 2) and 12–17 µm wide proximally (x = 15 µm; n = 2); distally, it is slightly narrower, with the terminal aperture oblique. The accessory stylet I (Figs 1A, 2A, E: as1; 1E) is tubular, 70 µm long (n = 1), 4 µm wide proximally (n = 1), and 2 µm wide distally (n = 1); its terminal aperture is oblique. The accessory stylet II (Figs 1A, 2E: as2; 1F) is needle-shaped, 59 µm long (n = 1), and 3 µm wide proximally (n = 1); it is slightly curved in the distal half and ends in a pointing tip. The proportions between the stylets were calculated following the methods of Artois et al. (2013): α = (length of the accessory stylet I / length of the prostatic stylet) × 100 = 98–103%; β = (length of the accessory stylet II / length of the prostatic stylet) × 100 = 83–87%; γ = (length of the accessory stylet II / length of the accessory stylet I) × 100 = 84%. The vitellaria (Figs 1A, 2A: vi) run at the body sides, from just behind the pharynx to almost the caudal end of the body. The left vitellarium was much smaller than the right one but this may be caused by of squeezing or orientation of the animal. The ovaries (Fig. 1A: ov) are oval-shaped, located rostrally to the stylets; only a single oocyte was observed in each ovary. Remarks The new species, Brachyrhynchoides ortizi sp. nov., shows the diagnostic features of the genus, as listed by Artois et al. (2013): the proboscis is very small (less than 10% of the body length) and three stylets occur in the male atrial organs (a prostatic stylet type IV, an accessory stylet I, and an accessory stylet II). However, these features need revaluation as Tessens et al. (2014) showed the genus to be paraphyletic. Three species of Brachyrhynchoides were known until now: B. triplostylis Artois & Schockaert, 2013, B. acutus Artois & Schockaert, 2013, and B. oosterlyncki Willems, Reygel & Artois, 2013, which can be distinguished by differences in stylet morphology (Artois et al. 2013). The prostatic stylet type IV of B. ortizi sp. nov. is the shortest and widest with respect to that of its congeners (see Table 1). It is more similar in length to that of B. oosterlyncki; however, the prostatic stylet of B. ortizi is straight, slightly wider proximally (15 µm) than distally, and with the distal aperture oblique, whereas in B. oosterlyncki the stylet is 8 µm wide proximally and tapers to a distally-pointing tip. The other two species of Brachyrhynchoides have a much larger prostatic stylet (see Table 1). Furthermore, in B. triplostylis and B. acutus, the prostatic stylet is curved and gradually tapers to a sharp (B. acutus) or rounded (B. triplostylis) tip (Artois et al. 2013). According to Artois et al. (2013), the accessory stylet I in species of Brachyrhynchoides is connected to the larger accessory vesicle. However, no accessory vesicles were observed in B. oosterlyncki and, therefore, the authors considered the shorter stylet to be accessory stylet I. For comparative purposes, we will consider accessory stylet I the larger in all species. In B. ortizi sp. nov., the tubular accessory stylet I is 70 µm long, with the terminal aperture oblique, and more or less of the same width over its entire length. On the other hand, the accessory stylet I in B. oosterlyncki is shorter, needle-shaped, and wider proximally. The accessory stylet I of B. triplostylis and B. acutus is much larger (Artois et al. 2013) (see Table 1). The accessory stylet II in all species of Brachyrhynchoides is needle-shaped. The smallest stylet appears in B. oosterlyncki, followed by B. ortizi sp. nov., and it is much larger in B. triplostylis and B. acutus (see Table 1). The accessory stylet II of B. ortizi is slightly curved and its distal half ends in a pointed tip. It is similar in morphology to what is described for other species, with the exception of B. acutus, where the accessory stylet II is distinctly curved. The proportions between stylets vary greatly interspecifically (Table 1, see Artois et al. 2013).

Phonorhynchoides lalanai sp. nov. urn:lsid:zoobank.org:act: 94BB22AE-7C11-4ECB-A344-B8ACFB01CF28 Figs 1C, I–J, 2D, G, Table 2 Phonorhynchoides sp. in Leasi et al. 2018: 1–12. Diagnosis Species of Phonorhynchoides Beklemischev, 1927 with a prostatic stylet type IV ~114 µm long, proximally ~9 µm, narrowing to 5 µm wide distally; it is twisted in the middle. Accessory stylet type IV 105–106 µm long, narrowing from 4–5 µm wide proximally to 2 µm wide distally; slightly curved in the proximal half. Etymology Species named after the late Dr Rogelio Lalana (Marine Research Centre, Havana University, Cuba), prominent Cuban marine researcher, awarded with the National Prize of Marine Sciences of Cuba in 2012, for his outstanding contribution to the knowledge of marine invertebrates, mainly crustaceans. Material examined Holotype CUBA • 1 whole mount; Santiago de Cuba, Bueycabón; 19°57′38″ N, 75°57′28″ W; 6 Feb 2018; depth 0.5 m; sublitoral, fine-grained sand rich in organic matter, salinity 33 ‰; https://id.luomus.fi/KV.699; FMNH. Other material PANAMA • 2 whole mounts; Pacific Ocean, Isla Iguana; 07°38′06″ N, 79°59′48″ W; 6 Mar. 2016; depth 10 m; sublittoral, coarse sand with gravel, covered with organic matter; HU XIX.1.49–XIX.1.50. Description The specimens are unpigmented (Fig. 2D), ~ 1 mm long. The proboscis (Figs 1C, 2D: pr) is less than 10% of the body length. A pair of eyes is located just behind the pharynx (Figs 1C, 2D: e). The pharynx (Figs 1C, 2D: ph) is positioned in the anterior body half. A pair of testes (Fig. 1C: t) is located posterior to the pharynx. The prostatic stylet type IV (Figs 1C, 2G: ps4, 1I) is 110–120 µm long (x = 114 µm; n = 3) and narrows from a width of 8–11 µm proximally (x = 9 µm; n = 3) to 5 µm distally (n = 3); the distal end is rounded. At about midway, the prostatic stylet is twisted. The accessory stylet type IV (Figs 1C, 2G: as4, 1J) is 105–106 µm long (n = 3), slightly curved in the proximal half, and narrows from 4–5 µm wide proximally (n = 3) to 2 µm wide distally (n = 3); the distal end is oblique and sharp. The vitellaria (Fig. 1C: vi) run from just behind the pharynx to the caudal body end. The female bursa (Fig. 1C: b) is located beside the stylets; it is muscular but not bipartite. The ovaries (Fig. 1C: ov) are located rostrally to the stylets; they are more or less kidney-shaped, with the oocytes organised in a row; the oocytes distally increase in diameter. Remarks Phonorhynchoides lalanai sp. nov. exhibits the diagnostic features of Phonorhynchoides: the prostatic stylet type IV is larger than the accessory stylet type IV, and the female bursa is muscular but not bipartite (Willems et al. 2017). The prostatic stylet of P. lalanai sp. nov. is twisted at the end of its proximal half, while this structure is never twisted in the other six known species of the genus. For comparison, the prostatic stylet is undulated in P. carinostylis Ax & Armonies, 1987 and P. gondwanae Willems & Artois in Willems et al., 2017, corkscrew-shaped in the middle in P. somaliensis Schockaert, 1971, and almost straight in P. flagellatus Beklemischev, 1927, P. japonicus Ax, 2008, and P. minor Diez, Sanjuan, Reygel & Artois in Diez et al., 2018b (for details see Willems et al. 2017; Diez et al. 2018b). Furthermore, the prostatic stylet carries ornamentations in P. carinostylis (spiral ridge over the whole length) and P. japonicus (thickened proximally and short spiral ridge), which are missing in P. lalanai. In P. lalanai, the prostatic stylet is distally rounded, differing from that in P. minor (terminally oblique) and the other species (sharp tip). The prostatic stylet of P. lalanai. (~114 µm) is considerably longer than that of P. minor (53–58 µm), but shorter than that in the other species (see Table 2). The accessory stylet type IV of P. lalanai sp. nov. ends in an oblique tip, while it ends in a pointed tip in all other species of Phonorhynchoides. The accessory stylet of the new species (105–106 µm) is smaller than that of P. gondwanae and P. japonicus, but larger than that of the other species (see Table 2). The length proportion between the accessory stylet type IV and the prostatic stylet type IV is larger in the Caribbean species (P. lalanai 88–95%, P. minor 78–85%) than in their known congeners (Willems et al. 2017; Diez et al. 2018b) (see Table 2). Indeed, it is characteristic of P. lalanai and P. minor that the prostatic stylet and accessory stylet are similar in length. The distinct morphology of the sclerotised stylets, previously discussed, warrants the status of P. lalanai as a new species., Published as part of Diez, Yander L., Sanjuan, Claudia, Monnens, Marlies & Artois, Tom, 2023, New species of Polycystididae (Platyhelminthes: Kalyptorhynchia) from Cuba and the Pacific coast of Panama, pp. 67-86 in European Journal of Taxonomy 856 on pages 75-76, DOI: 10.5852/ejt.2023.856.2029, http://zenodo.org/record/7554565, {"references":["Leasi F., Sevigny J. L., Laflamme E. M., Artois T., Curini-Galletti M., Navarrete A. dJ., Di Domenico M., Goetz F., Hall J. A., Hochberg R., Jorger K. M., Jondelius U., Todaro M. A., Wirshing H. H., Norenburg J. L. & Thomas W. K. 2018. Biodiversity estimates and ecological interpretations of meiofaunal communities are biased by the taxonomic approach. Communications Biology 1: 1 - 12. https: // doi. org / 10.1038 / s 42003 - 018 - 0119 - 2","Willems W. R., Reygel, P., Van Steenkiste N., Tessens B. & Artois T. J. 2017. Kalyptorhynchia (Platyhelminthes: Rhabdocoela) from KwaZulu-Natal (South Africa), with the description of six new species. Zootaxa 4242 (3): 441 - 466. https: // doi. org / 10.11646 / zootaxa. 4242.3.2","Schockaert E. R. 1971. Turbellaria from Somalia 1. Kalyptorhynchia (part 1). Monitore Zoologico Italiano 4 (5): 101 - 122.","Ax P. 2008. Plathelminthes aus Brackgewassern der Nordhalbkugel. Abhandlungen der Mathematischnaturwissenschaftlichen Klasse, Jahrgang 2008, 1. Franz Steiner Verlag, Mainz.","Diez Y. L., Sanjuan C., Reygel P., Roosen P. & Artois T. 2018 b. First record of Polycystididae (Platyhelminthes, Kalyptorhynchia) from Cuba, with the description of a new genus and five new species, and remarks and the description of one new species from Panama. Zootaxa 4514 (1): 201 - 125. https: // doi. org / 10.11646 / zootaxa. 4514.1.9"]}

Sabulirhynchus ibarrae sp. nov. urn:lsid:zoobank.org:act: 1EA7110C-D687-42BB-87A7-1259A24E4E0E Figs 3E–F, 4 Diagnosis Species of Sabulirhynchus Artois & Schockaert, 2000 with a very long proboscis, representing 40% of the body length. Prostatic stylet type III plate-shaped, ~53 µm long, proximally tubular and with a ridge at its midlength. Seminal reservoir exhibits a proximal apparently sclerotised cap. Etymology Species named after the late Dr María Elena Ibarra Martín (Marine Research Centre, Havana University, Cuba), head of the MRC for more than 25 years, who indefatigably championed the protection of oceans. Awarded with the National Prize of Environmental Sciences of Cuba in 2007. The Research Group of Marine Ecology of Universidad de Oriente carries her name. Material examined Holotype CUBA • 1 whole mount; Santiago de Cuba, Siboney; 19°57′34″ N, 75°42′07″ W; 7 Feb. 2019; depth 3 m; sublittoral, coarse-grained sand, salinity 34 ‰; https://id.luomus.fi/KV.700; FMNH. Other material CUBA • 1 whole mount; same collection data as for holotype; photographs of live specimens available; HU XIX.2.08. Description The specimens are unpigmented (Fig. 4A), ~ 1.5 mm long. The proboscis (Fig. 4A–B: pr) attains 40% of the body length. Caudally to the proboscis there is a pair of eyes (Fig. 4A–B: e). The pharynx is at the midbody (Fig. 4A–B: ph). A testis (Fig. 4A–B: t) is located beside the pharynx and occupies the middle third of the body. The prostatic stylet type III (Figs 3E–F, 4C; 4A–B, 4D: ps3) is plate-shaped, 49–56 µm long (x = 53 µm; n = 2), and 20–21 µm wide proximally; it is proximally tubular and exhibits a ridge at its midlength. The vitellarium (Fig. 4A–B: vi) runs from the posterior end of the proboscis to the caudal body end. The oval ovary (Fig. 4B, D–E: ov) has the oocytes organised in a row. The female bursa (Fig. 4A–B, D: b) is positioned caudally to the male atrial organs. The spindle-shaped seminal receptacle (Fig. 4B, D–E: sr) is filled with sperm and proximally exhibits a seemingly sclerotised cap (Fig. 4D–E: sc). The gonopore opens at 80% (Fig. 4B: cg). Remarks Until now, the genus Sabulirhynchus included a single species: Sabulirhynchus axi. Sabulirhynchus ibarrae sp. nov. and S. axi share the diagnostic features of the genus: lack of accessory glandular organ in the male system, a plate-shaped prostatic stylet type III, and a pyriform seminal receptacle in the female atrium (Artois & Schockaert 2000). Considering the newly analysed material of both species, we add to the diagnosis of Sabulirhynchus the presence of a proximal, apparently sclerotised cap in the seminal receptacle. This feature is easily recognisable in live specimens; however, we did not distinguish it on the whole mounts. Therefore, the sclerotised nature of this structure is questionable. The prostatic stylet is similar in length in both species, 52–63 µm long in S. axi (population from the Galapagos) and ~53 µm in S. ibarrae sp. nov. However, it is more variable in the population of S. axi from Panama (46–76 µm long). The stylet of S. axi is a simple plate, distally turned backward (Artois & Schockaert 2000), whereas it is straight, proximally tubular, and with a ridge at its midlength in S. ibarrae sp. nov. These differences in stylet morphology warrant the status of a new species.

Djeziraia adriani sp. nov. urn:lsid:zoobank.org:act: 39C06707-C4B5-4640-9B0D-7CAC9784D00E Figs 1B, G–H, 2B–C, F Diagnosis Species of Djeziraia Schockaert, 1971 with paired seminal vesicles. Gonads and atrial organs located caudally in the body. Prostatic stylet type IV 92–93 µm long, curved, S-shaped in live animals. Etymology Species named after Dr Adrian David Trapero Quintana (Havana University, Cuba), specialist in freshwater ecology and the taxonomy of Odonata. Material examined Holotype CUBA • 1 whole mount; Santiago de Cuba, Sardinero; 19°57′42″ N, 75°47′00″ W; 18 Mar. 2021; intertidal, mangrove area surrounding the mouth of Río Sardinero, 80 m from the beach, sample of sediment with rotten leaves and branches, salinity 32 ‰; https://id.luomus.fi/KV.698; FMNH. Other material CUBA • 2 whole mounts; same collection data as for holotype; photographs of live specimens available; HU XIX.1.47–XIX.1.48. Description The live specimens are unpigmented (Fig. 2B–C), 0.8–0.9 mm long, measured on whole mounts. A pair of well-differentiated bristles (Figs 1B, 2B: bt) is located at the sides of the proboscis pore. The proboscis (Figs 1B, 2B: pr) represents less than 10% of the body length. A pair of eyes (Figs 1B, 2B: e) is located just behind the proboscis. The pharynx (Figs 1B, 2B: ph) is positioned in the anterior body half. The gonads and atrial organs occur in the caudal body half (Figs 1B, 2C). The testes are located rostrally to the ovaries. The paired seminal vesicles (Figs 1B, 2F: sv) open through a single ejaculatory duct into the copulatory bulb. The ejaculatory duct is surrounded by the prostate vesicle type IV (Figs 1B, 2F: pv4). The cell bodies of the prostatic glands are extracapsular and enter the copulatory bulb proximally. The prostatic stylet type IV (Figs 1B, 2C, F: ps4; 1G–H) is tubular and 92–93 µm long (n = 3). The proximal funnel-shaped part of the stylet is 9–10 µm wide, and it tapers to a distally rounded tip, subdistally 4 µm wide; the aperture is completely terminal. Oocytes are organised in a row and proximally diminish in diameter. The vitellaria run laterally, from the pharynx almost to the caudal body end. The female bursa is located next to the stylet. The common gonopore opens at 90%. Remarks Djeziraia adriani sp. nov. exhibits most diagnostic features of Djeziraia: the proboscis is very small, less than 10% of the body length; the atrial organs are located in the caudal body half; the prostate vesicle is interposed; and there is a single prostatic stylet type IV in the male atrium (cf. the other representatives of Phonorhynchoidinae Tessens, Janssen & Artois, 2014 with two or three stylets) (see Schockaert 1971; Artois & Schockaert 2001). A striking feature of the new species is the fact that there are two seminal vesicles, while there is only one in its congeners: Djeziraia euxinica (Mack-Fira, 1971) sensu Schockaert 1982, D. incana Artois & Schockaert, 2001, D. longystila Noreña, Damborenea, Faubel & Brusa, 2007, and D. pardii Schockaert, 1971. Furthermore, the presence of a diverticulum at the bursal stalk (Schockaert 1971) was not observed in our live specimens. Despite these differences, the overall morphology of the new species largely corresponds to what is described for Djeziraia, and we therefore provisionally include it in this genus. Molecular phylogenetic work may prove useful to confirm this preliminary classification. The prostatic stylet type IV of all species of Djeziraia is a simple tube: it is slender and very long (D. longystila and D. incana) or short and straight (D. euxinica and D. pardii). In D. euxinica, the stylet is longitudinally striated and ends in a small hook. The general morphology of the prostatic stylet of D. adriani sp. nov. is comparable to that of D. longystila and D. incana. However, it is S-shaped in live specimens of the new species. Furthermore, the prostatic stylet of D. adriani (92–93 µm) is shorter than that of D. longystila (~275 µm; Noreña et al. 2007), D. incana (~179 µm, 295 µm in one specimen; Artois & Schockaert 2001), and D. euxinica (105–120 µm; Mac-Fira 1971; Artois & Schockaert 2001), and larger than that of D. pardii (~84 µm; Schockaert 1971). Both the presence of paired seminal vesicles and the morphology of the stylet support the validity of the new species, Djeziraia adriani sp. nov.

Brachyrhynchoides ortizi sp. nov. urn:lsid:zoobank.org:act: 774F2120-7B24-4F35-82EE-C46D93D9D9A7 Figs 1A, D–F, 2A, E, Table 1 Diagnosis Species of Brachyrhynchoides Artois & Schockaert, 2013 with the prostatic stylet type IV tubular, ~70 µm long, ~15 µm wide proximally, distally slightly narrower; terminal aperture oblique. Accessory stylet I tubular, 70 µm long; accessory stylet II needle-shaped, 59 µm long. Etymology Species named after Dr Manuel Ortiz (Marine Research Centre, Havana University, Cuba), prominent Cuban marine researcher, for his outstanding contribution to the knowledge of marine invertebrates, mainly crustaceans. Material examined Holotype CUBA • 1 whole mount; Santiago de Cuba, Siboney; 19°57′34″ N, 75°42′07″ W; 7 Feb 2019; depth 2 m; sublittoral, coarse-grained sand with fragments of calcareous algae, salinity 34 ‰; https://id.luomus.fi/KV.697; FMNH. Other material CUBA • 1 whole mount; same collection data as for holotype; photographs of live specimens available; HU XIX.1.46. Description The live specimens are unpigmented (Fig. 2A), ~ 1.5 mm long. The proboscis (Figs 1A, 2A: pr) measures less than 10% of the body length. A pair of eyes (Figs 1A, 2A: e) is located caudally to the proboscis. The pharynx (Figs 1A, 2A: ph) is located in the anterior body half. A pair of testes (Figs 1A, 2A: t) is located caudally to the pharynx. The prostatic stylet type IV (Figs 1A, 2A, 2E: ps4; 1D) is tubular, 68–71 µm long (x = 70 µm; n = 2) and 12–17 µm wide proximally (x = 15 µm; n = 2); distally, it is slightly narrower, with the terminal aperture oblique. The accessory stylet I (Figs 1A, 2A, E: as1; 1E) is tubular, 70 µm long (n = 1), 4 µm wide proximally (n = 1), and 2 µm wide distally (n = 1); its terminal aperture is oblique. The accessory stylet II (Figs 1A, 2E: as2; 1F) is needle-shaped, 59 µm long (n = 1), and 3 µm wide proximally (n = 1); it is slightly curved in the distal half and ends in a pointing tip. The proportions between the stylets were calculated following the methods of Artois et al. (2013): α = (length of the accessory stylet I / length of the prostatic stylet) × 100 = 98–103%; β = (length of the accessory stylet II / length of the prostatic stylet) × 100 = 83–87%; γ = (length of the accessory stylet II / length of the accessory stylet I) × 100 = 84%. The vitellaria (Figs 1A, 2A: vi) run at the body sides, from just behind the pharynx to almost the caudal end of the body. The left vitellarium was much smaller than the right one but this may be caused by of squeezing or orientation of the animal. The ovaries (Fig. 1A: ov) are oval-shaped, located rostrally to the stylets; only a single oocyte was observed in each ovary. Remarks The new species, Brachyrhynchoides ortizi sp. nov., shows the diagnostic features of the genus, as listed by Artois et al. (2013): the proboscis is very small (less than 10% of the body length) and three stylets occur in the male atrial organs (a prostatic stylet type IV, an accessory stylet I, and an accessory stylet II). However, these features need revaluation as Tessens et al. (2014) showed the genus to be paraphyletic. Three species of Brachyrhynchoides were known until now: B. triplostylis Artois & Schockaert, 2013, B. acutus Artois & Schockaert, 2013, and B. oosterlyncki Willems, Reygel & Artois, 2013, which can be distinguished by differences in stylet morphology (Artois et al. 2013). The prostatic stylet type IV of B. ortizi sp. nov. is the shortest and widest with respect to that of its congeners (see Table 1). It is more similar in length to that of B. oosterlyncki; however, the prostatic stylet of B. ortizi is straight, slightly wider proximally (15 µm) than distally, and with the distal aperture oblique, whereas in B. oosterlyncki the stylet is 8 µm wide proximally and tapers to a distally-pointing tip. The other two species of Brachyrhynchoides have a much larger prostatic stylet (see Table 1). Furthermore, in B. triplostylis and B. acutus, the prostatic stylet is curved and gradually tapers to a sharp (B. acutus) or rounded (B. triplostylis) tip (Artois et al. 2013). According to Artois et al. (2013), the accessory stylet I in species of Brachyrhynchoides is connected to the larger accessory vesicle. However, no accessory vesicles were observed in B. oosterlyncki and, therefore, the authors considered the shorter stylet to be accessory stylet I. For comparative purposes, we will consider accessory stylet I the larger in all species. In B. ortizi sp. nov., the tubular accessory stylet I is 70 µm long, with the terminal aperture oblique, and more or less of the same width over its entire length. On the other hand, the accessory stylet I in B. oosterlyncki is shorter, needle-shaped, and wider proximally. The accessory stylet I of B. triplostylis and B. acutus is much larger (Artois et al. 2013) (see Table 1). The accessory stylet II in all species of Brachyrhynchoides is needle-shaped. The smallest stylet appears in B. oosterlyncki, followed by B. ortizi sp. nov., and it is much larger in B. triplostylis and B. acutus (see Table 1). The accessory stylet II of B. ortizi is slightly curved and its distal half ends in a pointed tip. It is similar in morphology to what is described for other species, with the exception of B. acutus, where the accessory stylet II is distinctly curved. The proportions between stylets vary greatly interspecifically (Table 1, see Artois et al. 2013)., Published as part of Diez, Yander L., Sanjuan, Claudia, Monnens, Marlies & Artois, Tom, 2023, New species of Polycystididae (Platyhelminthes: Kalyptorhynchia) from Cuba and the Pacific coast of Panama, pp. 67-86 in European Journal of Taxonomy 856 on pages 70-71, DOI: 10.5852/ejt.2023.856.2029, http://zenodo.org/record/7554565, {"references":["Artois T., Willems W., Reygel P. & Schockaert E. 2013. Brachyrhynchus n. gen. n. sp., a new genus of Polycystididae Graff, 1905 (Rhabdocoela: Kalyptorhynchia), with the description of three new species from the Mediterranean and the Indian Ocean. Zootaxa 3635 (2): 127 - 136. https: // doi. org / 10.11646 / zootaxa. 3635.2.3","Tessens B., Janssen T. & Artois T. 2014. Molecular phylogeny of Kalyptorhynchia (Rhabdocoela, Platyhelminthes) inferred from ribosomal sequence data. Zoologica Scripta 43 (5): 519 - 530. https: // doi. org / 10.1111 / zsc. 12066"]}

The origin of introduced Nile tilapia stocks in sub-Saharan Africa is largely unknown. In this study, the potential of monogeneans as a biological tag and magnifying glass is tested to reveal their hosts' stocking history. The monogenean gill community of different Nile tilapia populations in sub-Saharan Africa was explored, and a phylogeographic analysis was performed based on the mitogenomes of four dactylogyrid species (Cichlidogyrus hani, C. sclerosus, C. thurstonae, and Scutogyrus longicornis). Our results encourage the use of dactylogyrids as biological tags. The magnifying glass hypothesis is only confirmed for C. thurstonae, highlighting the importance of the absence of other potential hosts as prerequisites for a parasite to act as a magnifying glass. With the data generated here, we are the first to extract mitogenomes from individual monogeneans and to perform an upscaled survey of the comparative phylogeography of several monogenean species with unprecedented diagnostic resolution. The Special Research Fund of Hasselt University finances MG (7NI02), AJCL (BOF19OWB02) and MPMV (BOF20TT06). Molecular work was funded through research grant 1513419 N of the Research Foundation—Flanders (FWO-Vlaanderen), and part of leading to results presented in this publication was carried out with infrastructure funded by the European Marine Biological Research Centre (EMBRC) Belgium, FWO-Vlaanderen project GOH3817N. The field expedition to the DRC was partly financed by the Stichting ter Bevordering van het Biodiversiteitsonderzoek in Afrika (SBBOA) fund.the research We appreciate the help of the people involved in the field work and sampling procedure. Furthermore, we would like to thank Christopher Laumer (EMBL-European Bioinformatics Institute, UK) and Gontran Sonet (Royal Belgium Institute of Natural Sciences, Belgium) for providing us with the extraction protocol and R scripts, respectively. We could also like to acknowledge Wim Bert, Christoph Hahn, Nikol Kmentova, ´ Jos Snoeks, and Carl Vangestel for suggestions on an earlier version of this manuscript. Finally, we would like to thank Ria Vanderspikken (Hasselt University, Belgium) and Natascha Steffanie (Hasselt University, Belgium) for their technical support in the laboratory

Orostylis gallicus sp. nov. Gobert, Monnens & Artois (Figs. 3F, 4F) Localities. More or less 70 m in front of a cliff at Wimereux beach, Wimereux, France (50��45���36���N; 1��41���31���E) Sand and shell gravel among algae scraped of rocks (Sep. 16, 2015): Type locality. More or less 70 m in front of a cliff at Wimereux beach, Wimereux France (50��45���36���N; 1��41���31���E) Red algae on rocks (Sep. 16, 2015). Material. Two whole mounts, one of which designated holotype (FMNH KV.695), the other one in the HU reference collection (HU XIV.3.10). Etymology. The species is named after the ancient Celtic people that inhabited the region of the type locality (Lat. ���gallicus��� = Gallic). Description. Based on observations of the whole mounts, the general morphology is as described for the genus, with the copulatory organ located anteriorly in the body, lateral to the pharynx. The number of testes is unknown. The stylet (Figs. 3F, 4F) is a strongly curved, ���raptor-claw���-shaped hollow spine, and is 45���51 ��m long. The proximal part is funnel-shaped and has an asymmetric aperture with a rounded flap. The distal third of the stylet is thin and tapers into a sharp tip. Laterally, the stylet shows a narrow, longitudinal slit. Additional details of the male copulatory system and female genital system could not be observed on the available specimens., Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on page 37, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911

Orostylis asinaraensis sp. nov. Gobert, Jouk, Revis & Artois (Figs. 3B���C, 4A) Localities. Cala Sant���Andrea, Asinara National Park, Sardinia, Italy (41��00���48���N; 8��14���56���E) Sand from 2 m deep (Sep. 27, 2014): Type locality. Cala dei Ponzesi, Asinara National Park, Sardinia, Italy (41��05���14���N; 08��20���45���E) Sand from the intertidal (Sep. 30, 2014). Material. Observations on live specimens. Two whole mounts, one of which designated holotype (FMNH KV.691), the other deposited in the HU XIV.3.06. Etymology. Species named after the National Park and island of Asinara, Sardinia, where the species was discovered. Description. Specimens are transparent, unpigmented. A pair of round eyes (Fig. 4A: e) is present anteriorly. The overall internal organisation of the specimens corresponds to that of Orostylis dohae sp. nov. The mouth is situated ventrally, near the anterior body end. A horizontally positioned cylindrical pharynx (Fig. 4A: ph) is situated in the anterior third of the body. The anterior edge of the pharynx bears several small papillae, but long tentacles as in O. dohae sp. nov. were not observed. The single testis (Fig. 4A: t) is situated ventrally around the midbody. The male copulatory system lies alongside the pharynx. It consists of a large copulatory bulb containing a seminal vesicle (Fig. 4A: sv) and prostatic vesicle. In live specimens, circular muscles clearly surround the copulatory bulb. The seminal and prostate vesicles enter the stylet separately. The stylet (Figs. 3B,C; 4A: st) is a strongly curved, ���raptor-claw���-shaped, hollow spine, with a ���handle-like��� extension projecting proximally. In one of the specimens (HU XIV.3.06), the stylet is straighter, with the distal third bent to one side (Fig. 3C). The total stylet (incl. the handle) measures 64���76 ��m (x = 70 ��m; n = 2). The handle is 15���19 ��m long (x = 17 ��m; n = 2). The stylet shows a longitudinal slit on one side. Based on observations of live specimens, it is likely that the male system opens into the oral cavity, as is the case in O. dohae sp. nov. An ovary (Fig. 4A: ov) was observed in the midbody. It is large and, together with the intestine, takes up most of the posterior two thirds of the body. A single vitellarium fills the caudal end of the body, with two large branches stretching forwards up to the level of the copulatory organ., Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on pages 33-34, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911

Orostylis timucuorum sp. nov. Smith III (Figs 3H, 5, S 1���S 3) Localities. Small beach facing the intracoastal waterway near the boat launch and pier, Whitney Marine Laboratory, FL (29��40���14���N; 81��12���57���W) Muddy sand with oyster shells and shell fragments (May 21, 2019): Type locality. Bear Island, NC (approximately 34��38���51���N; 77��07���02���W) Muddy sand-flat near tidal drainage stream (Jun., 2018). Outer sandy beach on Bogue Banks, Emerald Isle Site, NC (34��38���42���N; 77��05���23���W) Surface sediment halfway between MTL and LTL (Mar. 15, 2013). ���Anne McCrary���s Mudflat��� (muddy sand-flat facing the intracoastal waterway near Wilmington, NC ���approximately 34��13���11���N; 77��48���49���W) (Jan. and Feb., 1970) by R. M. Rieger. Bogue Inlet, NC. Shallow subtidal in ��� Amphioxus sand��� (date unknown) by R. M. Rieger. Material. Five specimens studied alive; two turned into whole mounts; one designated holotype (FMNH KV.696); the other reference material (HU XIV.3.19); three specimens examined by confocal microscopy; three live-drawings made by R. M. Rieger. Etymology. The specific epithet is in honour of the people (called ���Timucua��� by the Spanish) who first inhabited the region near the type locality. Description. Living, sexually mature specimens from the type locality measure 705���895 ��m long; all specimens possess a pair of pigmented eyes, as well as the general characters of the genus (Fig. 5A). The pharynx averages 16% of the body length (Fig. 5A: ph; n = 3). The pharynx bears 6 club-tipped, distal tentacles (Figs. 5A inset, S1). Radial pharyngeal musculature is thickly arranged and pseudostriated (Fig. 5B: rm). The male organ is directed forward and lies just behind or beside the pharynx; testes are paired (Figs. 5A: t, S2). The ovary is V-shaped, with paired germinal zones, sometimes giving the impression of two ovaries (Figs. 5A,C: ov). The vitellarium is either very large, or paired, situated immediately behind the ovary and extending posteriorly (Fig. 5C: vit). A bursal tissue lies in the ventral midline at approximately the level of the ovaries (Fig. 5A,D: bu). Confocal microscopy reveals a musculature associated with this that appears to lead to a mid-ventral pore (Figs. 5D,E: red arrow). The 58-��mlong stylet ranges in length from 47 to 69 ��m (n = 5), possessing a flared base with two distinct areas (Figs. 3H, 5F���G; 5H: sb, st). The stylet appears to have separate pathways for sperm and prostatic secretions. The stylet has a lateral slit that extends at least partway along it (Fig. 5F, arrows). Squeezing apparently flattens a stylet that, at rest, comprises a base with an elongate, semi-circular tip whose point rests in a small ���cup��� (Fig. 5H: green arrow); the base and tip are in nearly orthogonal planes (Fig. 5H: red arrows). Connection of the male canal with the pharynx tube could not be confirmed with the material at hand., Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on page 37, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911

Orostylis dohae sp. nov. Gobert, Van Steenkiste & Artois (Figs. 2, 3A, 4D) Neodalyellida n. gen. n. sp. 2 in Van Steenkiste et al. (2013) Neodalyellida sp. 2 in Stephenson et al. (2019) Localities. Doha, Qatar (25��19���04���N; 51��32���18���E) Sand at about the high-water mark (Mar. 19, 2008): Type locality. Material. Observations on live specimens. One whole mount designated holotype (FMNH KV.690), and two serially sectioned specimens (HU XIV.3.04��� XIV.3.05). Etymology. Species named after the capital of Qatar, where the species was discovered. Description. Animals are about 0.6 mm long (measured on whole mount), with two dark brown, kidney-shaped eyes (Figs. 2A, 4D: e). The epidermis is syncytial, strongly ciliated, and 2���5 ��m thick. The cilia measure 2���3 ��m. Nuclei in the epidermis are scarce. A thin basal membrane underlies the epidermis, followed by a circular and a longitudinal muscle layer, respectively. Several basophilic, coarse-grained glands are situated in the anterior end of the body, in the area surrounding the mouth. The caudal end of the body contains eosinophilic cement glands. The mouth is located near the anterior end of the body (Fig. 2A: m) and surrounded by a sphincter. A long, thin-walled oral tube connects the mouth opening to the pharynx. The pharynx (Figs. 2, 4D: ph) is located in the anterior body half and is between 1/4 and 1/5 of the body length long. The pharynx is cylindrical in shape, with a conspicuous musculature, including radial, circular, and longitudinal muscles. This is typical for the pharynx doliiformis in neodalyellids, but the radial muscles are very wide and stacked closely together with little or seemingly no space between them. The anterior end of the pharynx bears a ���collar��� (Fig. 2A: phc) separated by a constriction from the rest of the pharynx. This collar is provided with three pairs of tentacles projecting anteriorly (Figs. 2A, 4D: pht). The intestine (Fig. 2B: i) lies caudally from the ovary (Fig. 2: ov). In live specimens, diatom frustules were observed inside the intestinal tract. The large, paired testes are situated just anterior to the midbody (Figs. 2, 4D: t), behind the pharynx, on either side of the body. In live specimens, two distinct testes were clearly observed. However, in the serial sections, the separation between both testes was less obvious, creating the impression of a single, large testis. The two testes lie against one another in such a way that the spermatogenic distal ends of the testes point laterally.A pair of vasa deferentia extend anteriorly and connect the testes to the seminal vesicle (Figs. 2, 4D: sv) in the proximal half of the male copulatory organ. The copulatory organ is situated in the anterior part of the body, alongside the pharynx. It consists of the round to ovoid seminal vesicle (Figs. 2, 4D: sv), followed distally by a small, globular prostate vesicle (Fig. 2B: pv) filled with eosinophilic gland secretions. The seminal and prostate vesicle are lined with a syncytial, nucleated epithelium and surrounded by circular muscles. In the distal half of the copulatory organ, the seminal vesicle connects directly to a sclerotised stylet (Figs. 2, 4D: st; 3A). The stylet is a simple, thin-walled funnel, curved at an angle of about 90�� at its midpoint. The stylet is 33 ��m long and 9 ��m wide proximally. It connects to a long male duct, which opens in the oral cavity (Fig. 2B: oc). The female genital system consists of a large, curved ovary (Fig. 2: ov), positioned at the midbody, dorsally to and in front of the intestine. A female duct or gonopore was not observed. Instead, the oviduct appears to connect directly to the intestinal lumen. It is assumed that eggs are deposited in the intestinal lumen and expelled from the body via the mouth. Eosinophilic glands are present in the region where the ovary connects to the intestine. In the same area, vesicles with sperm were observed in the intestinal wall (Fig. 2A: isv). Possibly, these vesicles are resorptive and function as a bursa. The posterior half of the body is almost completely taken up by a lobed or branched vitellarium (Fig. 2B: vit)., Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on pages 31-33, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911, {"references":["Van Steenkiste, N., Tessens, B., Willems, W., Backeljau, T., Jondelius, U. & Artois, T. (2013) A comprehensive molecular phylogeny of Dalytyphloplanida (Platyhelminthes: Rhabdocoela) reveals multiple escapes from the marine environment and origins of symbiotic relationships. PLoS ONE, 8, e 59917. https: // doi. org / 10.1371 / journal. pone. 0059917","Stephenson, I., Van Steenkiste, N. W. L. & Leander, B. S. (2019) Molecular phylogeny of neodalyellid flatworms (Rhabdocoela), including three new species from British Columbia. Journal of Zoological Systematics and Evolutionary Research, 57, 41 - 57. https: // doi. org / 10.1111 / jzs. 12243"]}

Orostylis gen. nov. Gobert, Armonies, Diez, Jouk, Monnens, Revis, Reygel, Smith III, Van Steenkiste & Artois Etymology. The name Orostylis is derived from the Latin ���os��� (mouth), and ���stylis��� (stylet). The name refers to the fact that the male copulatory apparatus connects to the mouth in the type species. Diagnosis. Anterior-facing, cylindrical pharynx and sclerotised stylet in the anterior part of the body. Male genital opening in the oral cavity. Single ovary and vitellarium (O. timucuorum sp. nov. might have two vitellaria). No other female genital structures. Testes paired or unpaired. No visible connection between the female genital system and the environment, except possibly in O. timucuorum sp. nov. Grammatical gender. masculine Type species. Orostylis dohae, sp. nov., described below., Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on page 31, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911

Orostylis distortus sp. nov. Armonies, Gobert & Artois (Figs. 3G, 4C) Orostylis distortus n. n. in Armonies (2017) Localities. Sylt, Germany (55��04���44���N; 5��17���31���E) Sublittoral, 8.2 m deep, clean fine sand (Apr. 28, 2015): Type locality. Material. Observations on live specimens, one of which whole mounted and designated holotype (FMNH KV.693). Etymology. The specific name refers to the stylet morphology (Lat. ���distortus��� = distorted). Description. General morphology as described for the genus, with the stylet located anteriorly, lateral to the pharynx. The body is unpigmented, 0.8 mm (resting) to 1.2 mm long (swimming). The anterior and posterior body ends are more or less rounded. The mouth opens terminally or subterminally and is surrounded by few tactile hairs. Two pigmented eye spots (Fig. 4C: e) are situated anterior to the pharynx. The pharynx (Fig. 4C: ph) is cylindrical, with six 30-��m-long tentacles (Fig. 4C: pht). The proximal 1/3 of the tentacles��� length is anchored in the pharynx, which seems to have no circular muscles in this area and therefore differs in appearance from the distal part of the pharynx. The pharynx is only 1/8 of the body length and relatively small compared to the pharynx in other species of the genus. The paired testes are located laterally between the pharynx and the midbody. The copulatory organ lies beside the pharynx or directly behind it in stretched specimens. Its musculature is hardly visible in live specimens. A single, elongated seminal vesicle (Fig. 4C: sv) and prostatic vesicle (Fig. 4C: pv) enter the stylet proximally. The stylet (Figs. 3G; 4C: st) is S-shaped, 42 ��m long and consists of a proximal oval funnel, which rapidly narrows to a coiled, slender, 2���3-��m-wide tube ending in a pointed tip. At its proximal end, a longitudinal slit was observed. A singly ovary is present in the midbody, with the largest egg cells occurring anteriorly. The paired vitellaria stretch from the midbody to the rear body end., Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on pages 34-35, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911, {"references":["Armonies, W. (2017) Long-term change of meiofaunal species composition in a sandy beach, with description of 7 new species of Platyhelminthes. Helgoland Marine Research, 71, 12. https: // doi. org / 10.1186 / s 10152 - 017 - 0492 - 0"]}

Orostylis donanae sp. nov. Van Steenkiste, Gobert & Artois (Figs. 3E, 4E) Neodalyellida n. gen. n. sp. 1 in Van Steenkiste et al. (2013) Neodalyellida sp. 1 in Stephenson et al. (2019) Localities. Do��ana National Park, Andalusia, Spain (36��52���16���N; 06��25���45���W) Sand from Do��ana beach sampled at the low water mark, at 10 km north from the Guadalquivir river mouth (Apr. 6, 2008): Type locality. Do��ana National Park, Andalusia, Spain (36��47���57���N; 6��23���21���W) Sand from Do��ana beach sampled at the low water mark, at the Guadalquivir river mouth (Apr. 6, 2008). Material. Observations on live specimens. Two whole mounts, one of which designated holotype (FMNH KV.694), the other one deposited in the HU reference collection HU XIV.3.09. Etymology. Species epithet named after the type locality in Do��ana National Park, Spain. Description. Specimens have an elongate body with a pair of small, bean-shaped eyes near the anterior end. Whole-mounted specimens are about 0.5 (holotype) and 0.9 mm (HU XIV.3.09) long respectively. The pharynx is cylindrical in shape and located just behind the eyes. Based on observations of live specimens and whole mounts, the general internal organisation appears similar to that of Orostylis dohae sp. nov., with two testes just behind the pharynx. The male copulatory organ is situated alongside the pharynx, in the anterior part of the body, with the distal end pointing anteriorly. The copulatory bulb contains an elongate seminal vesicle and connects distally to a sclerotised stylet. This stylet (Figs. 3E, 4E) consists of a corkscrew-shaped folded plate or ���gutter��� and is 74���94 ��m long. The proximal base of the stylet is about 15 ��m wide and bears an extension that is folded towards the anterior. As no serial slides were available for this species, it is not clear whether the male gonopore opens into the oral cavity, as is the case in Orostylis dohae sp. nov. No details on the anatomy of the female genital system could be observed on live specimens alone., Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on pages 35-36, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911, {"references":["Van Steenkiste, N., Tessens, B., Willems, W., Backeljau, T., Jondelius, U. & Artois, T. (2013) A comprehensive molecular phylogeny of Dalytyphloplanida (Platyhelminthes: Rhabdocoela) reveals multiple escapes from the marine environment and origins of symbiotic relationships. PLoS ONE, 8, e 59917. https: // doi. org / 10.1371 / journal. pone. 0059917","Stephenson, I., Van Steenkiste, N. W. L. & Leander, B. S. (2019) Molecular phylogeny of neodalyellid flatworms (Rhabdocoela), including three new species from British Columbia. Journal of Zoological Systematics and Evolutionary Research, 57, 41 - 57. https: // doi. org / 10.1111 / jzs. 12243"]}

Orostylis caecus sp. nov. Diez & Artois (Figs. 3D, 4B) Localities. Bah��a Larga, Guam�� municipality, Santiago de Cuba province, Cuba (19��58���57���N; 76��18���15���W) Intertidal, very fine sand in the upper 10 cm of the sediment, salinity 34��� (Apr. 5, 2017): Type locality. Bah��a de Gibara, Holgu��n province, Cuba (21��06���00���N; 76��08���09���W) Intertidal, on very fine sand with organic material close to the mouth of the river, salinity 32 ��� (Feb. 17, 2016). Material. Observations on four live specimens, three of which were whole mounted afterwards, one designated holotype (FMNH KV.692), the others deposited in the HU XIV.3.07��� XIV.3.08. Etymology. The specific name refers to the species��� lack of eye spots (Lat. ���caecus��� = blind). Description. General morphology as described for the species above, with the stylet located anteriorly, lateral to the pharynx (Fig. 4B: ph, st). The body is unpigmented, slender, and 0.25���0.42 mm long (measured on two whole-mounted specimens). Eye spots are lacking. The mouth opens subterminally and is surrounded by few tactile hairs. The pharynx (Fig. 4B: ph) is 1/6���1/3 of the body length in live animals, measuring 104���120 ��m in two whole mounts and bearing six slender tentacles anteriorly (Fig. 4B: pht). The paired testes are located at both sides of the pharynx, each one connected to a seminal vesicle. The two seminal vesicles enter a small prostate vesicle. The stylet (Figs. 3D; 4B: st) is formed by a broad, proximal piece (Fig. 3D: bp) and a distal, small, hollow hook (Fig. 3D: h). The entire stylet is 24���31 ��m long (x = 29 ��m; n = 3) and 14���20 ��m wide (x = 16 ��m; n = 3). The hook is 8���15 ��m long (x = 11 ��m; n = 3) and 3���5 ��m wide at its base (x = 4 ��m; n = 3). The broad piece is partially filled by a granular secretion, either originating from the prostate vesicle or part of the prostate vesicle itself. A single ovary (Fig.4B: ov) is situated in the midbody and is surrounded by the gut., Published as part of GOBERT, STEFAN, ARMONIES, WERNER, DIEZ, YANDER L., JOUK, PHILIPPE, MONNENS, MARLIES, REVIS, NATHALIE, REYGEL, PATRICK, SMITH, JULIAN III, STEENKISTE, NIELS VAN & ARTOIS, TOM, 2022, Orostylis gen. nov., a new genus of Dalytyphloplanida with seven new species (Platyhelminthes: Rhabdocoela), pp. 29-46 in Zootaxa 5115 (1) on page 34, DOI: 10.11646/zootaxa.5115.1.2, http://zenodo.org/record/6346911

Orostylis gen. nov. Gobert, Armonies, Diez, Jouk, Monnens, Revis, Reygel, Smith III, Van Steenkiste & Artois Etymology. The name Orostylis is derived from the Latin “os” (mouth), and “stylis” (stylet). The name refers to the fact that the male copulatory apparatus connects to the mouth in the type species. Diagnosis. Anterior-facing, cylindrical pharynx and sclerotised stylet in the anterior part of the body. Male genital opening in the oral cavity. Single ovary and vitellarium (O. timucuorum sp. nov. might have two vitellaria). No other female genital structures. Testes paired or unpaired. No visible connection between the female genital system and the environment, except possibly in O. timucuorum sp. nov. Grammatical gender. masculine Type species. Orostylis dohae, sp. nov., described below.

Krumbachia subterranea Reisinger, 1933 Fig. 8A–C Material examined Neotype GERMANY • 1 spec., studied alive and sagittally sectioned; Hessen; 50°46′30″ N, 09°30′18″ E; 9 Aug. 2011; A.M. Houben and W. Proesmans leg.; submersed meadow at the banks of the Breitenbach creek; neotype no. 823; HU. Reference material GERMANY • 1 spec., live observations; same collection data as for neotype. Description The examined specimens are around 2.5 mm long. The body is slender with a somewhat pointy anterior end and rounded posteriorly (see Fig. 8A). Adenal rhabdite glands occur just behind the brain (Fig. 8A: ar). Paired protonephridiopores (pp) are positioned ventrally, very near to the mouth (Fig. 8A: pp). A rosulate pharynx (Fig. 8A: ph) is situated just behind the centre of the body. The gonopore (Fig. 8A–C: gp) is located at ±75% of the body and connected to the gonoduct (Fig. 8B– C: gd). The gonoduct is surrounded by an inner circular and outer longitudinal muscle layer, and lined with a ciliated, nuclear epithelium resembling the epidermis. The genital atrium (Fig. 8A–C: ga) is surrounded by a similar musculature and lined with a high, nucleated epithelium. On both lateral sides of the genital atrium, a group of proliferating cells (Fig. 8C: pc) is found. A large group of eosinophilic glands is situated posterior to the genital atrium and probably enters this atrium anteriorly (not drawn on the reconstruction). The large, egg-shaped testes (Fig. 8A: t) lie anterior to the pharynx and ventral to the vitellaria (Fig. 8A– B: vi). Paired vasa deferentia unite to form a single vas deferens (Fig. 8A–C: vde) just before entering the copulatory bulbus (Fig. 8A: co). Two layers of spiral muscles surround the long, curved copulatory organ, which bends up to 80° towards its distal end. The copulatory organ bears an intracapsular seminal vesicle (Fig. 8B–C: vs) and a strongly sclerotised ejaculatory duct (Fig. 8B–C: de). Several coarsegrained, extracapsular eosinophilic glands (Fig. 8A–C: gg) enter the copulatory organ at the proximal end. Their secretion is lightly basophilic when entering the copulatory organ, however, it becomes strongly eosinophilic in the ejaculatory duct. A cone-shaped bursa (Fig. 8A–C: bu), surrounded by strong inner circular and outer longitudinal muscles, lies next to the copulatory organ and opens into the genital atrium. The vitellaria extend from the region of the rhabdite glands to the posterior end (Fig. 8A: vi). The vitelloducts (Fig. 8C: vd) fuse just before opening into the female duct (Fig. 8C: fd). Furthermore, this duct is surrounded by a layer of circular muscles and receives the oviduct, a seminal receptacle (Fig. 8A–C: rs), and the female glands (Fig. 8C: fg). The seminal receptacle is provided with a short stalk, which also is surrounded by circular muscles. Discussion See the general discussion on the genus Krumbachia Reisinger, 1924. Previously known distribution Ruhr, Germany (Reisinger 1933), riparian forest near Schlitz, Germany (Schwank 1981). Common species in Europe (Lanfranchi & Papi 1978)., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 90-92, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Reisinger E. 1933. Neues zur vitalen Nervenfarbung. (Gleichzeitig ein Beitrag zur Kenntnis des Protoplanelliden-Nervensystems). Verhandlungen der deutschen Zoologischen Gesellschaft: 155 - 160.","Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143.","Kepner W. A. & Carter J. S. 1931. Olisthanella virginiana nov. sp. Zoologischer Anzeiger 95: 87 - 94.","Ruebush T. K. 1938. Krumbachia minuta n. sp. (Turbellaria Rhabdocoela). Zoologischer Anzeiger 122: 260 - 265.","Schwank P. 1981. Seltene und wenig bekannte Strudelwurmer (Turbellaria) aus Quellen und Bergbachen Mitteleuropas. Beitrage zur Naturkunde in Osthessen 17: 101 - 131.","Lanfranchi A. & Papi F. 1978. Turbellaria (excl. Tricladida). In: Illies J. (ed.) Limnofauna Europaea: 5 - 18. G. Fischer, Stuttgart."]}

Genus Faunulus Houben, Proesmans & Artois gen. nov. urn:lsid:zoobank.org:act: 18E72BA0-D92B-4504-8E17-BD6497247BCA Type species Faunulus nielsi Houben, Proesmans & Artois gen. et sp. nov. Diagnosis ‘Typhloplanidae’ with adenal rhabdites in two anterior tracts, dermal rhabdites could be present distally. Eyes absent. Pharynx slanted obliquely forward and in the central body part. With rod-shaped glands at rostral and caudal body end. Testes differ in size and lie anterior to the pharynx. Copulatory organ with straight, armed cirrus. Seminal receptacle inside of the oviduct. Bursa copulatrix absent. Etymology The genus name refers to the habitat where this taxon was found and is derived from the Latin ‘Faunulus’ (m.), meaning ‘forest dweller’., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on page 75, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040

Hoplopera opaca Reisinger, 1924 Fig. 7D–F Material examined AUSTRIA • 1 spec., studied alive and sagittally sectioned; Hohe Rannach near Graz; 47°09′53″ N, 15°24′50″ E; 26 Aug. 2011; A.M. Houben and W. Proesmans leg.; leafy humus of a birch forest; XIV.2.42; HU. Description Our specimen is about 1 mm long and very dark. The anterior end is rounded, with the posterior end showing a distinct tail with pronounced eosinophilic tail glands (Fig. 7D: tg). Small dermal rhabdites occur all over the body. Adenal rhabdites are rather inconspicuous and only visible on the sectioned specimen. Paired protonephridiopores (Fig. 7D: pp) open posterior to the mouth. A rosulate pharynx (Fig. 7D: ph) is positioned at ±75% of the body. The gonopore (Fig. 7E–F: gp) is situated at ±80% of the body and connected to a genital atrium (Fig. 7D– F: ga), which is surrounded by muscles and lined with a high epithelium. The vasa deferentia (Fig. 7F: vde) enter the copulatory organ (Fig. 7D–F: co) separately. This copulatory organ is a 20 µm long, oval structure surrounded by muscles of uncertain orientation. It contains sperm in its proximal part, which probably serves as a seminal vesicle. An ejaculatory duct was not observed. Intracapsular prostate glands (Fig. 7E: gg) were observed on live specimens. The male duct is surrounded by circular muscles. The bipartite bursa (Fig. 7D–F: bu) bears a thin-walled, proximal part containing sperm and a long distal part, the bursal stalk (Fig. 7E–F: bs). This stalk is surrounded by circular muscles and contains a sclerotised structure (Fig. 7E: ss). It seems to consist of several vertical bars, which are fused in the distal part. The vitellaria were still developing in the studied specimen, but already reach up to ±33% of the body. The female duct (Fig. 7F: fd) connects the oviduct (Fig. 7F: od) and vitelloduct (Fig. 7F: vd) to the genital atrium. Discussion See the general discussion on the genus Hoplopera. Previously known distribution Near Graz, Austria, in moist forest soils (Reisinger 1924). General discussion on Hoplopera All species of Hoplopera are characterised by a combination of features: pharynx situated in the caudal body half, presence of dermal rhabdites and adenal rhabdites, the latter organised in rostral tracks (i.e., Stäbchenstassen), presence of tail glands, lack of a stylet, and the presence of a bursa copulatrix (see Van Steenkiste et al. 2010). This combination of features is also shown by Rhomboplanilla bryophila Schwank, 1980. However, species of Hoplopera all have a sclerotised structure in the bursa copulatrix, which is absent in R. bryophila. Species of Hoplopera either occur in limnoterrestrial environments (H. isis Houben, Proesmans & Artois sp. nov.; H. macropharynx Reisinger, 1924; H. maculata Reisinger, 1924; and H. opaca), or in marine to brackish habitats (H. littoralis Karling, 1957 and H. pusilla Ehlers, 1974). However, the marine origin of H. littoralis and H. pusilla has been questioned. Based on its sampling locality, Karling 1957 and Ax 2008 suggested that H. littoralis might as well be a limnoterrestrial species. H. pusilla was found in the supratidal of salty meadows with salinity below 10‰ and was therefore deemed brackish instead of limnoterrestrial (Armonies 1987). All limnoterrestrial species possess a bipartite bursa, with the distal part (probably the bursal stalk) containing a sclerotised structure, while the bursa of the ‘marine’ animals consists of only one part. Furthermore, the vasa deferentia of the limnoterrestrial species enter the copulatory organ separately (Reisinger 1924), while they fuse just before entering the copulatory organ in H. littoralis and H. pusilla (Karling 1957; Ehlers 1974). Both the ecological and morphological differences suggest that Hoplopera may as well be split into two genera. Awaiting a thorough cladistic analysis, however, we prefer to maintain the taxon Hoplopera containing both limnoterrestrial and ‘marine’ animals. The limnoterrestrial species of Hoplopera are most easily distinguished from each other by the shape of the sclerotised structure in the bursa. The fish pot-shaped sclerotic structure as seen in Hoplopera isis Houben, Proesmans & Artois sp. nov. is unique within the genus. In the other three limnoterrestrial species, this structure consists of 6–8 bars proximally connected to a ring (H. macropharynx), 4 (rarely 5) elongated, spoon-shaped structures accompanied with two longitudinal plates (H. maculata) or 6–10 longitudinal bars with broadened distal ends and small protrusions towards the genital atrium (H. opaca) (Reisinger 1924). None of these species possesses the three horizontal bars present in H. isis Houben, Proesmans & Artois sp. nov. Apart from the above-mentioned differences, H. isis Houben, Proesmans & Artois sp. nov. can also be distinguished from H. opaca and H. macropharynx by the presence of a seminal receptacle, a feature it shares with H. maculata. H. opaca has pronounced tail glands, while the tail glands of H. isis Houben, Proesmans & Artois sp. nov. are small and inconspicuous. H. macropharynx has a conspicuous, large, and oval pharynx, which is unique among the species discussed. H. maculata is the largest of all limnoterrestrial species of Hoplopera (1.5 mm vs. at most 1 mm for the other three species) and has typical parenchymal refracting spots (for details, see Reisinger 1924)., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 88-89, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143.","Van Steenkiste N., Davison P. & Artois T. 2010. Bryoplana xerophila n. g. n. sp., a new limnoterrestrial microturbellarian (Platyhelminthes, Typhloplanidae, Protoplanellinae) from epilithic mosses, with notes on its ecology. Zoological Science 27 (3): 285 - 291. https: // doi. org / 10.2108 / zsj. 27.285","Karling T. G. 1957. Drei neue Turbellaria Neorhabdocoela aus dem Grundwasser der schwedischen Ostseekuste. Kungliga fysiografiska sallskapets i Lund forhandlingar 27: 25 - 33.","Ehlers U. 1974. Interstitielle Typhloplanoida (Turbellaria) aus dem Litoral der Nordseeinsel Sylt. Mikrofauna des Meeresbodens 49: 427 - 526.","Ax P. 2008. Plathelminthes aus Brackgewassern der Nordhalbkugel. Akademie der Wissenschaften und der Literatur. Franz Steiner Verlag, Stuttgart.","Armonies W. 1987. Freilebende Plathelminthen in supralitoralen Salzwiesen der Nordsee: Okologie einer borealen Brackwasser-Lebensgemeinschaft. Microfauna Marina 3: 81 - 156."]}

Genus Bryoplana Van Steenkiste, Davison & Artois, 2010 Type species Bryoplana xerophila Van Steenkiste, Davison & Artois, 2010. Remark As Bryoplana belgica Houben, Proesmans & Artois sp. nov. is only the second species to be described within the genus, we here provide a new, emended diagnosis for Bryoplana Van Steenkiste, Davison & Artois, 2010, as well as the type species Bryoplana xerophila Van Steenkiste, Davison & Artois, 2010. For further details, please refer to the discussion on B. belgica Houben, Proesmans & Artois sp. nov. below. Diagnoses Bryoplana Diagnosis amended after Van Steenkiste et al. 2010. Genus of ‘Protoplanellinae’ without dermal or adenal rhabdites. Eyes absent. Pharynx somewhat elongate, in anterior part of body and slanting obliquely forward. Paired testes near the caudal body end and ventrocaudal to the vitellaria. Simple muscular tube as copulatory organ. Bursa copulatrix absent. Bryoplana xerophila Species of Bryoplana with the body completely covered by cilia. Testes small, globular. Copulatory organ without any sclerotisation. Without seminal vesicle., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on page 81, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Van Steenkiste N., Davison P. & Artois T. 2010. Bryoplana xerophila n. g. n. sp., a new limnoterrestrial microturbellarian (Platyhelminthes, Typhloplanidae, Protoplanellinae) from epilithic mosses, with notes on its ecology. Zoological Science 27 (3): 285 - 291. https: // doi. org / 10.2108 / zsj. 27.285"]}

Protoplanella simplex Reisinger, 1924 Fig. 11 Material examined Neotype GERMANY • 1 spec., live observations and sagittal sections; Kordel; 49°49′24″ N, 06°38′06″ E; 24 Jul. 2011; A.M. Houben and W. Proesmans leg.; mosses growing on a wall; neotype no. 825; HU. Other material GERMANY • 1 spec., serially sectioned; same collection data as for neotype; XIV.3.11; HU • 2 specs, live observations, one of which serially sectioned; Bavaria, Oberau; 07°33′33″ N, 11°06′57″ E; 13 Jul. 2011; A.M. Houben and W. Proesmans leg.; forest litter; XIV.3.12; HU • 5 specs, live observations, three of which serially sectioned; Lanaken; 50°56′03″ N; 05°39′36″ E; 27 Jul. 2011; A.M. Houben and W. Proesmans leg.; mosses at the forest edge; XIV.3.13–XIV.3.15; HU • 4 specs, live observations, two of which serially sectioned; Lanaken, National Park ‘ Hoge Kempen’; 50°56′02″ N; 05°39′38″ E; 27 Jul. 2011; A.M. Houben and W. Proesmans leg.; moist forest soil; XIV.3.16–XIV.3.17; HU. Description The studied specimens are about 0.8 mm long. The anterior and posterior body ends are rounded (Fig. 11A). Rhabdite glands are present and arranged into two groups behind the brain (Fig. 11A: ar); the rhabdites themselves extend forward in two anastomosing tracts. Dermal rhabdites were not observed. The paired protonephridiopores (Fig. 11A: pp) open laterally and somewhat caudal to the rosulate pharynx (Fig. 11A, C: ph), which is situated just behind the middle of the body. The gonopore (Fig. 11A–C: gp) is located at ±80% of the body and connected to a genital atrium (Fig. 11A–C: ga). The genital atrium is surrounded by an inner circular and outer longitudinal muscle layer. The small, round testes (Fig. 11A–B: t) lie posterior to the pharynx and ventral to the vitellaria (Fig. 11A–C: vi). Both vasa deferentia (Fig. 11B–C: vde) enter the copulatory organ (Fig. 11A: co) separately from the lateral side. This 22 µm long, oval-shaped copulatory organ is surrounded by two layers of spiral muscles and contains an intracapsular seminal vesicle (Fig. 11B–C: vs) with a low, nucleated epithelium and an ejaculatory duct (Fig. 11B–C: de), which is surrounded by two layers of spiral muscles. Extracapsular, eosinophilic prostate glands (Fig. 11A–C: gg) open laterally into the copulatory organ. A male duct (Fig. 11C: md) with the same musculature as the genital atrium connects the copulatory organ to the latter. The paired vitellaria extend from 25% of the body to the posterior end where they fuse via a broad anastomosis. A single ovary (Fig. 11A–C: ov) is closely associated with one of the vitellaria forming an ovovitellarium. The female duct (Fig. 11C: fd) is surrounded by the same musculature as the genital atrium and receives a club-shaped seminal receptacle (Fig. 11A–C: rs) and ovovitelloduct at its proximal end. Fine-grained, eosinophilic glands (Fig. 11C: fg) surround and enter the female duct. Discussion See the general discussion on the genus Protoplanella. Remarks Intensive surveys at the type locality yielded no specimens. The specimens from Oberau, Bavaria, Germany, which is relatively close to the original type locality in Graz, Austria, are of poor quality. Therefore, a specimen from Kordel, Germany was designated neotype, since all diagnostic features are exactly as described by Reisinger (1924). Previously known distribution In the vicinity of Graz, Austria in forest humus (Reisinger 1924, 1954; An der Lan & Franz 1954; An der Lan 1963), on the Faroe Islands (Steinböck 1931); near Poznań, Poland, in moss and litter (Kolasa 1974). General discussion on Protoplanella As mentioned by Van Steenkiste et al. (2011), the identification of Protoplanella simplex is challenging. New material found during several sampling trips showed a need for type material to unravel the morphological differences between all known descriptions of P. simplex. Reisinger (1924) originally described animals with round testes; vasa deferentia that open separately from the lateral side of the copulatory organ; a vitellarium and ovovitellarium connected to each other over a broad anastomosis; and a seminal receptacle that opens into the proximal part of the female duct. Luther (1963) described a specimen with elongated testes; a bursa that could be a seminal receptacle near the male copulatory organ; and, judging from his illustration, most probably paired ovovitellaria. Also, Van Steenkiste et al. (2011) describe a sack-like protrusion at the genital atrium (which was not mentioned by Reisinger 1924); a female bursa (which was called a seminal receptacle by Reisinger 1924) containing remnants of sperm; and their illustration shows the vasa deferentia uniting while entering the copulatory organ at the proximal side. The descriptions of Luther (1963) and Van Steenkiste et al. (2011) differ substantially from that of Reisinger (1924) and, therefore, we consider them not to refer to representatives of P. simplex. Here, we consider these descriptions as referring to a new species: Protoplanella leiae Houben, Proesmans & Artois sp. nov. Moreover, the description of Luther (1963) indicates some, albeit smaller, differences with that of Van Steenkiste et al. (2011). The illustration made by Luther (1963) is not detailed and only made from live specimens. Since Luther’s drawings are in general more detailed, we assume this illustration was based on sub-ideal circumstances, which yielded a quickly made sketch. For now, we consider the specimens described by Luther (1963) and Van Steenkiste et al. (2011) to be members of the same species since differences are small and, in the case of Luther, not based on thoroughly studied material., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 98-99, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143.","Reisinger E. 1954. Edaphische Kleinturbellarien als bodenkundliche Leitformen. Mitteilungen des Naturwissenschaftlichen Vereines fur Karnten 64: 106 - 123.","An der Lan H. & Franz H. 1954. Turbellaria. In: Franz H. (ed.) Die Nordost-Alpen im Spiegel ihrer Landtierwelt: 129 - 134. Universitatsverlag Wagner, Innsbruck.","An der Lan H. 1963. Zur Verbreitung edaphischer Kleinturbellarien in Osterreich. Berichte des Naturwissenschaftlich-Medizinischen Vereins in Innsbruck 53: 227 - 234.","Steinbock O. 1931. Freshwater Turbellaria. In: Jensen S., Lundbeck W. & Mortensen Th. (eds) Zoology of the Faroes: 1 - 32. Copenhagen.","Kolasa J. 1974. Badania nad wirkami (Turbellaria) zrodel ze szczegolnym uwzglednieniem okolic Poznania (The investigations on spring Turbellaria with a special regard to surroundings of Poznan). Badania Fizjograficzne nad polska zachodnia 26: 7 - 31.","Van Steenkiste N., Tessens B., Krznaric K. & Artois T. 2011. Dalytyphloplanida (Platyhelminthes: Rhabdocoela) from Andalusia, Spain, with the description of four new species. Zootaxa 2791: 1 - 29. https: // doi. org / 10.11646 / zootaxa. 2791.1.1","Luther A. 1963. Die Turbellarien Ostfennoskandiens IV. Neorhabdocoela 2. Typhloplanoida: Typhloplanidae, Solenopharyngidae und Carcharodopharyngidae. Fauna Fennica 16: 1 - 163."]}

Bryoplana belgica Houben, Proesmans & Artois sp. nov. urn:lsid:zoobank.org:act: 1F08C372-CBAE-45E6-BE50-144752F3D44B Fig. 5 Diagnosis Species of Bryoplana with the ciliation reduced or completely lacking dorsally. Testes elongated, in the posterior body part, lateral to the copulatory organ. Copulatory organ with bent, sclerotised ejaculatory duct. Most proximal part of female duct forming a seminal receptacle. Etymology The epithet refers to the fact that the species was found in Belgium. Material examined Holotype BELGIUM • 1 spec., studied alive and serially sectioned; Koksijde, Oostduinkerke, nature reserve ‘De Zeebermduinen’; 51°08′22″ N, 02°41′26″ E; 30 Jul. 2011; A.M. Houben and W. Proesmans leg.; dry moss growing on dunes; KV.687; FMNH. Description The specimen is about 0.8 mm long. Both body ends are rounded (Fig. 5A–B). Free swimming specimens show a small tail. Adenal rhabdite glands (Fig. 5A: ar) are situated in two groups at ±25% of the body. Dermal rhabdites and protonephridiopores were not observed. The epidermis on the ventral body side is 4.5 µm high and entirely covered with locomotory cilia, while on the dorsal body side it is 3.5 µm high and ciliation is strongly reduced, even almost completely lacking. A slightly forward-slanted rosulate pharynx (Fig. 5A–B: ph) is located just rostral to the centre of the body. The gonopore (Fig. 5C–D: gp) is situated at ±80% of the body and connected to a genital atrium (Fig. 5A, C–D: ga), which is lined with a high, nucleated epithelium and surrounded by muscles, the orientation of which could not be observed with certainty. The elongated testes (Fig. 5A, C–D: t) lie at ±70% of the body and ventrally to the paired vitellaria (Fig. 5A–D: vi). They gradually taper into the broad vasa deferentia (Fig. 5C: vde), which laterally enter the copulatory organ (Fig. 5A: co). Circular muscles surround the 34 µm long copulatory organ, which includes an intracapsular seminal vesicle (Fig. 5C–E: vs) and a 22 µm long, strongly sclerotised ejaculatory duct (Fig. 5C–E: de). This ejaculatory duct is more or less straight at its proximal end and bends strongly (±100°) at the distal end. Coarse-grained eosinophilic glands are situated ventrally to the copulatory organ. Although the entrance into the copulatory organ could not be seen, these glands probably represent the prostate glands (Fig. 5D: gg?). The female duct (Fig. 5C–D: fd) is relatively long and lined with a nuclear epithelium. Proximally, it widens into a seminal receptacle (Fig. 5A, C–D: rs), which receives the short oviduct (Fig. 5D: od). The vitelloduct and female glands (Fig. 5D: fg) open into this female duct at the place where it connects to the seminal receptacle. Discussion The new species can readily be placed within ‘Typhloplanidae’ because it possesses all diagnostic features: a pharynx rosulatus, a single ovary, paired testes, and a single genital opening. Furthermore, the ventral position of the testes relative to the vitellaria indicates this species should be placed in ‘Protoplanellinae’, ‘Rhynchomesostominae’ Bresslau, 1933 or ‘Typhloplaninae’ Graff, 1905. However, the species’ general habitus and internal organisation differ markedly from the situation in the latter two subtaxa, and we therefore designate this species to ‘Protoplanellinae’. Most representatives of ‘Protoplanellinae’ have the pharynx situated in the midbody or posterior body half. Only select species have a pharynx in the anterior half of the body, these belong to Achrochordonoposthia Reisinger, 1924; Bockia Reisinger, 1924; Bryoplana; Microcalyptorhynchus Kepner & Ruebush, 1935, Prorhynchella Ruebush, 1939; and Protopharyngiellona Schwank, 1980. Some of these genera show very typical features: presence of a proboscis (Microcalyptorhynchus), presence of ciliated pits in the anterior body half (Prorhynchella), or the fact that the proboscis is of the doliiformis-type (Bockia). Lack of these features in our species indicates that it cannot be allocated to any of these genera. One of the most eye-catching features of B. belgica Houben, Proesmans & Artois sp. nov. is the lack of a bursa copulatrix, which in the remaining taxa is only the case for Bryoplana. We hence allocate our specimens to the latter genus, to which it indeed shows much resemblance. Bryoplana belgica Houben, Proesmans & Artois sp. nov. differs from Bryoplana xerophila by the presence of a sclerotised, curved ejaculatory duct, the presence of a seminal receptacle in the female system, and the fact that the dorsal body ciliation is very much reduced, or even lacking. The latter feature was also mentioned by Kolasa (1977) for Ventrociliella romanae, which he suggested to be an adaptation to limnoterrestrial habitats. However, in all other typical limnoterrestrial taxa, even in B. xerophila, the dorsal ciliation is present. Both species of Bryoplana were recovered from dried out moss – B. xerophila in the USA and B. belgica Houben, Proesmans & Artois sp. nov. in Western Europe – but indeed differ markedly in the extent of the dorsal body ciliation, undermining Kolasa’s (1977) hypothesis. The presence/absence of a seminal receptacle in the female system as a distinguishing character should be used with care at this moment. Indeed, the seminal receptacle in B. belgica Houben, Proesmans & Artois sp. nov. is simply a swelling of the female duct, and not a separate organ. As such, the absence of this structure in B. xerophila may be due to the specimens of Van Steenkiste et al. (2010) not having mated yet. However, as Van Steenkiste et al. (2010) investigated several live specimens and twelve serial sections, this seems unlikely. Regardless, the differences in body ciliation and construction of the copulatory organ proper clearly distinguish both species.

Ventrociliella romanae Kolasa, 1977 Fig. 3 Material examined AUSTRIA • 1 spec., serially sectioned; near Graz, Hohe Rannach; 47°09′53″ N, 15°24′50″ E; 26 Aug. 2011; A.M. Houben and W. Proesmans leg.; leafy humus of a birch forest; XIV.2.34; HU • 1 spec., live observations; Graz, Rohrenberg; 47°07′44″ N, 15°24′53″ E; 26 Aug. 2011; A.M. Houben and W. Proesmans leg.; between dead leaves • 2 specs, serially sectioned; Graz, Kanzelkügel; 47°06′49″ N, 15°23′11″ E; 26 Aug. 2011; leafy humus; XIV.2.35–XIV.2.36; HU • 1 spec., live observations; Weyer, Kreuzberg; 47°51′36″ N, 14°39′09″ E; 26 Aug. 2011; A.M. Houben and W. Proesmans leg.; humus of a mixed forest • 4 specs, live observations, one of which serially sectioned; Weyer, Kreuzberg; 47°51′29″ N, 14°39′14″ E; 26 Aug. 2011; A.M. Houben and W. Proesmans leg.; moss growing on a dead trunk; XIV.2.37; HU. Description and discussion The specimens from Austria are about 0.8mm long and very dark due to their gut content (Fig. 3B). Habitus and internal organs are as described by Kolasa (1977), with the exception that protonephridiopores of one specimen (not drawn) are situated just anterior to the pharynx and not lateral to or slightly behind the pharynx as originally described. However, in most specimens, they are situated at ±50% of the body (pp, Fig. 3A). Due to the small size of the specimens, it was not possible to make a thorough reconstruction of the reproductive structures from the sectioned specimens. Although Ventrociliella romanae was originally placed within ’Protoplanellinae’, it was recently listed as a taxon incertae sedis within Dalytyphloplanida (Van Steenkiste et al. 2010). Awaiting the inclusion of this taxon in molecular phylogenetic analyses, we for now keep this genus as incertae sedis, with probably a high affiliation to ‘Protoplanellinae’: Kolasa (1977) considered V. romanae closely related to the protoplanellin Bockia deses Reisinger, 1924 because of their similar habitus, the position of the male reproductive organ, the construction of the pharynx, and their limnoterrestrial lifestyle. Indeed, the only drawing ever published of B. deses (Reisinger 1954: fig. 10) closely resembles the drawing we constructed of a free-swimming specimen of V. romanae (Fig. 3B). Considering their similarity, and especially since the description of B. deses is based on a single specimen, a re-assessment of the validity of these species is warranted. As we found new material of V. romanae on the type locality of B. deses, we here present a detailed morphological comparison between both species. Kolasa (1977) stated that V. romanae and B. deses differ due to the presence of (1) a real pharynx doliiformis, (2) the lack of adenal rhabdites, (3) the absence of a bursa, (4) the occurrence of ciliation all over the body, (5) the lack of a seminal receptacle, and (6) a sclerotised ejaculatory duct. However, the pharynx of V. romanae is strongly tilted forwards, which makes it possible to describe it as a pharynx doliiformis (1). Furthermore, in some of our specimens of V. romanae, adenal rhabdites are barely visible and may easily be overlooked (2). The bursa originally described by Kolasa (1977) was sometimes seen as a large genital atrium, a characteristic also mentioned in the description of B. deses (Reisinger 1924) (3). Reisinger (1924) never made any remarks on body ciliation. Indeed, this is a rather subtle characteristic and may have easily been missed on a single specimen (4). As the seminal vesicle of V. romanae is merely an accumulation of sperm in the oviduct, it could be easily overlooked if it is not filled. Therefore, the absence of this vesicle in B. deses has little diagnostic value (5). The only clear difference between the two species may be that the ejaculatory duct of B. deses is slightly sclerotised, while it is muscular in V. romanae. However, considering their small size and the absence of sectioned material of B. deses, the reliability of this characteristic is also questionable (6). Finally, the typical, conspicuous, vacuolated epidermis of V. romanae was never mentioned for B. deses. As all presumed differences are questionable to some degree, it is highly likely that V. romanae and B. deses belong to the same genus or perhaps are synonyms. In the latter case, V. romanae would become the junior synonym of B. deses. Resolving this possible synonymy is a challenging task, as specimens identified as either species are reported from the same (type) locality. A more exhaustive resampling effort on this sampling locality may provide more clarity: Microscopical study of a large sample may or may not reveal a consistent difference in the above-mentioned morphological traits, possibly demonstrating their diagnostic value. Sequencing morphologically vouchered representatives of both presumed species and subsequent molecular delineation methods may then provide further evidence for the validity of these taxa. However, with the data available today, Bockia deses is better considered a nomen dubium. Previously known distribution Forest soil near the stream Fosso Contesora in Tuscany, Italy (Kolasa 1977)., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 77-79, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Kolasa J. 1977. A new representative of terrestrial Typhloplanoida (Turbellaria) - Ventrociliella romanae gen. nov., sp. nov. Bulletin de l'Academie polonaise des sciences. Serie des sciences biologiques 25: 39 - 43.","Van Steenkiste N., Davison P. & Artois T. 2010. Bryoplana xerophila n. g. n. sp., a new limnoterrestrial microturbellarian (Platyhelminthes, Typhloplanidae, Protoplanellinae) from epilithic mosses, with notes on its ecology. Zoological Science 27 (3): 285 - 291. https: // doi. org / 10.2108 / zsj. 27.285","Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143.","Reisinger E. 1954. Edaphische Kleinturbellarien als bodenkundliche Leitformen. Mitteilungen des Naturwissenschaftlichen Vereines fur Karnten 64: 106 - 123."]}

Bryoplana belgica Houben, Proesmans & Artois sp. nov. urn:lsid:zoobank.org:act: 1F08C372-CBAE-45E6-BE50-144752F3D44B Fig. 5 Diagnosis Species of Bryoplana with the ciliation reduced or completely lacking dorsally. Testes elongated, in the posterior body part, lateral to the copulatory organ. Copulatory organ with bent, sclerotised ejaculatory duct. Most proximal part of female duct forming a seminal receptacle. Etymology The epithet refers to the fact that the species was found in Belgium. Material examined Holotype BELGIUM • 1 spec., studied alive and serially sectioned; Koksijde, Oostduinkerke, nature reserve ‘De Zeebermduinen’; 51°08′22″ N, 02°41′26″ E; 30 Jul. 2011; A.M. Houben and W. Proesmans leg.; dry moss growing on dunes; KV.687; FMNH. Description The specimen is about 0.8 mm long. Both body ends are rounded (Fig. 5A–B). Free swimming specimens show a small tail. Adenal rhabdite glands (Fig. 5A: ar) are situated in two groups at ±25% of the body. Dermal rhabdites and protonephridiopores were not observed. The epidermis on the ventral body side is 4.5 µm high and entirely covered with locomotory cilia, while on the dorsal body side it is 3.5 µm high and ciliation is strongly reduced, even almost completely lacking. A slightly forward-slanted rosulate pharynx (Fig. 5A–B: ph) is located just rostral to the centre of the body. The gonopore (Fig. 5C–D: gp) is situated at ±80% of the body and connected to a genital atrium (Fig. 5A, C–D: ga), which is lined with a high, nucleated epithelium and surrounded by muscles, the orientation of which could not be observed with certainty. The elongated testes (Fig. 5A, C–D: t) lie at ±70% of the body and ventrally to the paired vitellaria (Fig. 5A–D: vi). They gradually taper into the broad vasa deferentia (Fig. 5C: vde), which laterally enter the copulatory organ (Fig. 5A: co). Circular muscles surround the 34 µm long copulatory organ, which includes an intracapsular seminal vesicle (Fig. 5C–E: vs) and a 22 µm long, strongly sclerotised ejaculatory duct (Fig. 5C–E: de). This ejaculatory duct is more or less straight at its proximal end and bends strongly (±100°) at the distal end. Coarse-grained eosinophilic glands are situated ventrally to the copulatory organ. Although the entrance into the copulatory organ could not be seen, these glands probably represent the prostate glands (Fig. 5D: gg?). The female duct (Fig. 5C–D: fd) is relatively long and lined with a nuclear epithelium. Proximally, it widens into a seminal receptacle (Fig. 5A, C–D: rs), which receives the short oviduct (Fig. 5D: od). The vitelloduct and female glands (Fig. 5D: fg) open into this female duct at the place where it connects to the seminal receptacle. Discussion The new species can readily be placed within ‘Typhloplanidae’ because it possesses all diagnostic features: a pharynx rosulatus, a single ovary, paired testes, and a single genital opening. Furthermore, the ventral position of the testes relative to the vitellaria indicates this species should be placed in ‘Protoplanellinae’, ‘Rhynchomesostominae’ Bresslau, 1933 or ‘Typhloplaninae’ Graff, 1905. However, the species’ general habitus and internal organisation differ markedly from the situation in the latter two subtaxa, and we therefore designate this species to ‘Protoplanellinae’. Most representatives of ‘Protoplanellinae’ have the pharynx situated in the midbody or posterior body half. Only select species have a pharynx in the anterior half of the body, these belong to Achrochordonoposthia Reisinger, 1924; Bockia Reisinger, 1924; Bryoplana; Microcalyptorhynchus Kepner & Ruebush, 1935, Prorhynchella Ruebush, 1939; and Protopharyngiellona Schwank, 1980. Some of these genera show very typical features: presence of a proboscis (Microcalyptorhynchus), presence of ciliated pits in the anterior body half (Prorhynchella), or the fact that the proboscis is of the doliiformis-type (Bockia). Lack of these features in our species indicates that it cannot be allocated to any of these genera. One of the most eye-catching features of B. belgica Houben, Proesmans & Artois sp. nov. is the lack of a bursa copulatrix, which in the remaining taxa is only the case for Bryoplana. We hence allocate our specimens to the latter genus, to which it indeed shows much resemblance. Bryoplana belgica Houben, Proesmans & Artois sp. nov. differs from Bryoplana xerophila by the presence of a sclerotised, curved ejaculatory duct, the presence of a seminal receptacle in the female system, and the fact that the dorsal body ciliation is very much reduced, or even lacking. The latter feature was also mentioned by Kolasa (1977) for Ventrociliella romanae, which he suggested to be an adaptation to limnoterrestrial habitats. However, in all other typical limnoterrestrial taxa, even in B. xerophila, the dorsal ciliation is present. Both species of Bryoplana were recovered from dried out moss – B. xerophila in the USA and B. belgica Houben, Proesmans & Artois sp. nov. in Western Europe – but indeed differ markedly in the extent of the dorsal body ciliation, undermining Kolasa’s (1977) hypothesis. The presence/absence of a seminal receptacle in the female system as a distinguishing character should be used with care at this moment. Indeed, the seminal receptacle in B. belgica Houben, Proesmans & Artois sp. nov. is simply a swelling of the female duct, and not a separate organ. As such, the absence of this structure in B. xerophila may be due to the specimens of Van Steenkiste et al. (2010) not having mated yet. However, as Van Steenkiste et al. (2010) investigated several live specimens and twelve serial sections, this seems unlikely. Regardless, the differences in body ciliation and construction of the copulatory organ proper clearly distinguish both species., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 81-83, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143.","Ruebush T. K. 1935. The genus Olisthanella in the United States. Zoologischer Anzeiger 112: 129 - 136.","Ruebush T. K. 1939. A new North American rhabdocoel turbellarian Prorhynchella minuta n. gen., n. sp. Zoologischer Anzeiger 127: 204 - 209.","Kolasa J. 1977. A new representative of terrestrial Typhloplanoida (Turbellaria) - Ventrociliella romanae gen. nov., sp. nov. Bulletin de l'Academie polonaise des sciences. Serie des sciences biologiques 25: 39 - 43.","Van Steenkiste N., Davison P. & Artois T. 2010. Bryoplana xerophila n. g. n. sp., a new limnoterrestrial microturbellarian (Platyhelminthes, Typhloplanidae, Protoplanellinae) from epilithic mosses, with notes on its ecology. Zoological Science 27 (3): 285 - 291. https: // doi. org / 10.2108 / zsj. 27.285"]}

Faunulus nielsi Houben, Proesmans & Artois gen. et sp. nov. urn:lsid:zoobank.org:act: E8B0D042-259A-427D-8F29-5DB6ED8C8411 Fig. 2 Diagnosis Provisionally the same diagnosis as the genus. Etymology The species epithet is dedicated to Niels Houben, son of the first author (A.M. Houben). Material examined Holotype AUSTRIA • 1 spec., live observations and sagittal sections; Kreuzberg near Weyer; 47°51′36″ N, 14°39′09″ E; 29 Aug. 2011; A.M. Houben and W. Proesmans leg.; forest soil of Pinus, Sambucus, Corylus, and Cornus; KV.686; FMNH. Paratypes AUSTRIA • 2 specs, live observations, one of which whole mounted; same collection data as for holotype; paratype no. 821; HU. Description Specimens about 1 mm long. The body shape is pointed anteriorly and blunt to rounded posteriorly (see Fig. 2A). On free-swimming specimens, a small tail can be observed. Both anterior and posterior ends possess very typical, strongly eosinophilic glands that appear rod-shaped, like big rhabdites, and are situated more or less parallel to each other. Rostrally, rhabdite glands (Fig. 2A: ar) are present and arranged in two groups. The distal part of the epidermis is completely filled with coarse, strongly eosinophilic secretions, which probably are dermal rhabdites (Fig. 2B: dr?). The protonephridiopores were not observed with certainty. The slightly forward slanted rosulate pharynx (Fig. 2A: ph) is located centrally. The gonopore (Fig. 2A–B: gp) is situated at ±65% of the body and connected to a genital atrium (Fig. 2A– B: ga) that is surrounded by muscles, although their orientation could not be observed with certainty. The paired, differently sized testes (Fig. 2A: t) lie in front of the pharynx and ventral to the paired vitellaria (Fig. 2A–B: vi). One testis is relatively large, while the other is barely visible. The paired vasa deferentia (Fig. 2B: vde) enter the copulatory organ laterally (Fig. 2A: co). Two layers of spiral muscles surround the 50 µm long copulatory organ, which bears an intracapsular seminal vesicle (Fig. 2B–C: vs) and a cirrus (Fig. 2B–C: cir). Large, coarse-grained, extracapsular eosinophilic glands (Fig. 2B: gg) are associated with the copulatory organ, although the point of entry remains uncertain. The 30 µm long cirrus is more or less straight and covered with spines in its distal part (see Fig. 2B–F: cir). The most distal part of the cirrus bears the larger spines and is enveloped in a conical, sclerotised pouch (Fig. 2C: sp). The female duct (Fig. 2B: fd) is relatively long and lined with a high, nuclear epithelium. Proximally it widens into a seminal receptacle (Fig. 2B: rs) that receives the oviduct and the vitelloduct. Discussion Faunulus nielsi Houben, Proesmans & Artois gen. et sp. nov. strongly resembles species of Adenocerca Reisinger, 1924 because of the combination of following features: centrally positioned pharynx, presence of tail glands and a spiny cirrus, and absence of a bursa (Van Steenkiste et al. 2010). However, F. nielsi Houben, Proesmans & Artois gen. et sp. nov. differs from all species of Adenocerca in having testes that lie rostral to the pharynx. In all species of Adenocerca, they are situated posterior to the pharynx and lie next to the copulatory organ. Moreover, there is a difference in size between the two testes of F. nielsi Houben, Proesmans & Artois gen. et sp. nov., which was never reported for Adenocerca. This size difference is consistent for all observed specimens. All species of Adenocerca either have no dermal rhabdites (Adenocerca teshirogii Kolasa, 1981) or dermal rhabdites occurring throughout the whole epidermis. Conversely, what we assume are dermal rhabdites occur solely in the caudal body part of F. nielsi Houben, Proesmans & Artois gen. et sp. nov. Because of the unique combination of features present in the new species described, we find it justified to erect a new genus within ‘Typhloplanidae’. Remarks Animals seem to feed on rotifers since trophi were found in the gut., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 75-77, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143.","Van Steenkiste N., Davison P. & Artois T. 2010. Bryoplana xerophila n. g. n. sp., a new limnoterrestrial microturbellarian (Platyhelminthes, Typhloplanidae, Protoplanellinae) from epilithic mosses, with notes on its ecology. Zoological Science 27 (3): 285 - 291. https: // doi. org / 10.2108 / zsj. 27.285"]}

Hoplopera isis Houben, Proesmans & Artois sp. nov. urn:lsid:zoobank.org:act: 4DA3359A-D279-4286-B7B0-822382D258F7 Fig. 7A–C Diagnosis Dark species of Hoplopera, about 0.8 mm long with inconspicuous tail glands. Dermal rhabdites small, adenal rhabdites in two tracks. Atrial glands present. Spindle-shaped testes. Copulatory organ 20 µm long, without sclerotised structures. Bipartite bursa with sclerotised structure containing two groups of parallel, vertical rods, separated from each other by vertical bars, as a whole resembling a fish pot. Female duct forming a seminal receptacle. Etymology The species epithet is dedicated to Isis Houben, first daughter of the first author (A.M. Houben). Material examined Holotype AUSTRIA • 1 spec., studied alive and horizontally sectioned; south of Graz, between Glashütten and Trahütten; 46°49′46″ N, 15°06′09″ E; 23 Aug. 2011; A.M. Houben and W. Proesmans leg.; moss growing in a small stream in a pine forest; KV.688; FMNH. Paratypes AUSTRIA • 5 specs, studied alive, one of which whole mounted; same collection data as for holotype; paratype no. 822; HU. Description Specimens are about 0.7–0.9 mm long. The body is rounded anteriorly and possesses a small tail provided with small, inconspicuous tail glands (Fig. 7C: tg). Rostrally, sharply pointed adenal rhabdites (Fig. 7B: ar) are arranged in two groups. Very small dermal rhabdites occur all over the body. The paired protonephridiopores (Fig. 7A: pp) lie posterior and lateral to the mouth. The rosulate pharynx is located just behind the middle of the body (Fig. 7A: ph). The gonopore (Fig. 7B–C: gp) is situated at ±80% of the body and connected to a genital atrium (Fig. 7A–C: ga) that is lined with a high epithelium and surrounded by muscles of uncertain orientation. At its posterior side, the genital atrium receives a large group of eosinophilic glands (Fig. 7A–C: ag). Two small, spindle-shaped testes (Fig. 7A: t) lie in front of the pharynx (Fig. 7A: ph) and ventral to the paired vitellaria (Fig. 7A, C: vi). In some specimens, one testis seems bigger than the other one. The paired vasa deferentia (Fig. 7B–C: vde) enter the egg-shaped copulatory organ laterally. Two layers of spiral muscles surround the 24µm long copulatory organ (Fig. 7A: co), which bears an intracapsular seminal vesicle (Fig. 7B–C: vs) and an ejaculatory duct (Fig. 7B–C: de). Coarse-grained intra- (Fig. 7B– C: gg1) and extracapsular (Fig. 7C: gg2) eosinophilic glands are associated with the copulatory organ. The relatively long male duct (Fig. 7C: md) receives the bursa (Fig. 7A–C: bu) before entering the genital atrium (Fig. 7A–C: ga). This bipartite bursa consists of an 18 µm long, thin-walled proximal part containing sperm and a 22 µm long distal part, which could be considered the bursal stalk (Fig. 7B–C: bs). This stalk is surrounded by circular muscles and contains a sclerotised structure (Fig. 7B: ss) that resembles the structure of a fish pot. It consists of vertical rods that are divided into two groups by a horizontal bar. The proximal and distal part are also delimited by a horizontal bar. As a whole, this bursal stalk is wrapped in a loose matrix surrounded by circular muscles. The vitellaria (Fig. 7A, C: vi) extend from the anterior third of the body to the posterior end where they meet. The oviduct broadens and becomes a seminal receptacle (Fig. 7A–C: rs), which further becomes a long female duct (Fig. 7C: fd), lined with a high, nucleated epithelium and surrounded by muscles. The vitelloduct was not observed with certainty, although it is probably an unpaired one that meets the oviduct. Discussion See the general discussion on the genus Hoplopera. Remarks The hard parts and copulatory structures are not visible on the whole-mounted specimen. Therefore, we designate a serially sectioned specimen as holotype., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 86-88, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143."]}

Adenocerca minima Kolasa, 1981 Fig. 4 Material examined AUSTRIA • 3 specs, studied alive, one of which whole mounted and a second one horizontally sectioned; south of Graz, between Glashütten and Trahütten; 46°49′46″ N, 15°06′09″ E; 23 Aug. 2011; A.M. Houben and W. Proesmans leg.; humid moss from a small stream in a pine forest; XIV.2.38 and XIV.3.18; HU. Description and discussion Specimens are about 0.6 mm long. Habitus and internal organisation correspond to the description of Kolasa (1981b). However, the original description, based on one specimen, mentions a much smaller animal (0.3 mm) (see Kolasa 1981b). Small dermal rhabdites are present all over the body. Protonephridiopores (Fig. 4A: pp) are situated lateral to the pharynx (Fig. 4A–B: ph). The two small testes (Fig. 4A–B: t) are situated caudally from the pharynx, at 65–70% of the body. Adenocerca minima clearly differs from all other representatives of Adenocerca by the orientation of the spines of its copulatory organ (see Fig. 4C–F). Small spines are present in the distal half of the cirrus and at the distal end, where 6 µm long, distally pointing, crescent-shaped spines form a crown (Fig. 4C: cs). Other species only possess small spines (A. clinopharynx Reisinger, 1924 and A. teshirogii) or have a different orientation of these spines, with the proximal spines being the biggest (A. bresslaui Reisinger, 1924). Remarks Kolasa (1981b) mentioned seven crown spines while we only counted six. Both Kolasa’s and our counts were made on a single specimen. Therefore, for the time being, we prefer to designate our specimens to the same species as Kolasa’s (1981b). Previously known distribution In wet mosses on the banks of the stream Fosso Contesora, Italy (Kolasa 1981b)., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 79-80, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Kolasa J. 1981 b. New semiterrestrial species of Protoplanellinae (Turbellaria, Typhloplanidae) associated with a submontane stream. Bulletin de l'Academie polonaise des sciences. Serie des sciences biologiques 28 (10 - 11): 611 - 616.","Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143."]}

Prorhynchella minuta Ruebush, 1939 Fig. 10 Material examined USA • 9 specs, live observations, one of which sagittally sectioned and two horizontally sectioned; Alabama, Ponderosa Lake; 32°54′53″ N, 87°19′28″ W; 27 May 2009; Niels Van Steenkiste leg.; submerged vegetation in shallow, clear water in the southeast corner of the lake; XIV.3.01–XIV.3.03; HU. Description and discussion Specimens are about 1 mm long (Fig. 10E) and can be placed within ‘Protoplanellinae’ due to the ventral position of the testes relative to the vitellaria and the separate protonephridiopores (see Reisinger 1924). Additionally, sectioned specimens clearly show ciliated pits (Fig. 10B: cp) at the anterior body end. Within ʻProtoplanellinae’, the only genus containing species with such pits is Prorhynchella (Van Steenkiste et al. 2010). Moreover, the studied specimens also possess the typical proboscis-like organ (Fig. 10B: plo) associated with a glandular complex (Fig. 10B: gl) that is unique for this monospecific genus (described as ‘rüssel-like organ’ by Ruebush 1939). The only difference between our specimens and the original description of P. minuta is the position of the protonephridiopores (Fig. 10A: pp), which are situated somewhat more posteriorly compared to the original description (Ruebush 1939). The studied specimens show some intraspecific variation in the structure of the bursa (Fig. 10A, C–F: bu). In one specimen, this is merely an evagination of the genital atrium while in another it is an oval, thin-walled structure, filled with sperm (compare Fig. 10C–D, F). It is connected to the genital atrium (Fig. 10A, D: ga) by a long bursal stalk (Fig. 10C, F: bs), which is surrounded by very strong sphincters (Fig. 10C, F: sph). Only two sphincters were visible on live specimens (Fig. 10F), but at least six were counted in one sectioned specimen (Fig. 10C). In the original description of P. minuta, Ruebush (1939) describes a bursa with a stalk, similar to the situation in most of our specimens (Fig. 10C, F). Whether or not the specimen drawn in Fig. 10D is an aberration is not clear: The specimen appears fully adult, hence the poorly developed bursal structure is unlikely a result of a different degree of development. With the data available to us, it is difficult to speculate on the biological significance of this reduced organ and we hence refrain from drawing conclusions on the matter. Previously known distribution Freshwater ponds near Pine Orchard, Connecticut, USA (Ruebush 1939)., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on pages 94-96, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Ruebush T. K. 1939. A new North American rhabdocoel turbellarian Prorhynchella minuta n. gen., n. sp. Zoologischer Anzeiger 127: 204 - 209.","Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143.","Van Steenkiste N., Davison P. & Artois T. 2010. Bryoplana xerophila n. g. n. sp., a new limnoterrestrial microturbellarian (Platyhelminthes, Typhloplanidae, Protoplanellinae) from epilithic mosses, with notes on its ecology. Zoological Science 27 (3): 285 - 291. https: // doi. org / 10.2108 / zsj. 27.285"]}

Olisthanellinella rotundula Reisinger, 1924 Fig. 9 Material examined AUSTRIA • 3 specs, studied alive, one of which sagittally sectioned and one of which horizontally sectioned; Graz, Kanzelkügel; 47°06′49″ N, 15°23′11″ E; 26 Aug. 2011; A.M. Houben and W. Proesmans leg.; forest soil; XIV.2.49–XIV.2.50; HU. Description and discussion The body length of the studied specimens is about 0.8 mm. Habitus and internal organisation correspond to the original description (Reisinger 1924). The most typical characteristics of this monospecific genus are: adenal rhabdites (Fig. 9A: ar) occurring only in rostral tracks; dermal rhabdites absent; a bipartite bursa (Fig. 9A–D: bu) with a muscular, sclerotised stalk (Fig. 9B, D: bs) and a thin-walled proximal part; and the copulatory organ (Fig. 9A: co) with a muscular ejaculatory duct (Fig. 9B, D: de) and a large seminal receptacle (Fig. 9C: rs) that opens into the oviduct (Fig. 9C: od). The opening of the vitelloduct was never clearly observed. Neither of our sectioned specimens clearly show both male and female reproductive structures. Therefore, and because of (for now) intraspecific differences (see below), we refrain from designating a neotype. Specimens described by Luther (1963) seem to be somewhat different from those described by Reisinger (1924) since they possess an egg-shaped bursa instead of a bipartite bursa and their oviduct functions as the seminal receptacle. Moreover, the specimens collected by Armonies (1987) were identified based on Luther’s (1963) description.As probably is the case for all protoplanellins, a thorough molecular analysis would help to solve which features are apomorphic/diagnostic for the taxon and help identification and delimitation of species. Therefore, we provisionally keep all within Olisthanellinella rotundula. Previously known distribution In the vicinity of Graz, Austria in moist forest soils (Reisinger 1924); North-East Alps, Austria in moist forest soil (An der Lan & Franz 1954); Oldenburg, Germany in humus of oak leaves (Reisinger in Luther 1963); Helsingfors, Finland in moss (Luther 1963); Sylt, Germany, in salt meadows (Armonies 1987)., Published as part of Houben, Albrecht M., Monnens, Marlies, Proesmans, Willem & Artois, Tom J., 2022, Limnoterrestrial ' Typhloplanidae' (Rhabdocoela, Platyhelminthes), with the description of four new species and a new genus, pp. 70-102 in European Journal of Taxonomy 798 on page 94, DOI: 10.5852/ejt.2022.798.1671, http://zenodo.org/record/6323040, {"references":["Reisinger E. 1924. Die terricolen Rhabdocoelen Steiermarks. Zoologischer Anzeiger 59: 33 - 48, 72 - 86, 128 - 143.","Luther A. 1963. Die Turbellarien Ostfennoskandiens IV. Neorhabdocoela 2. Typhloplanoida: Typhloplanidae, Solenopharyngidae und Carcharodopharyngidae. Fauna Fennica 16: 1 - 163.","Armonies W. 1987. Freilebende Plathelminthen in supralitoralen Salzwiesen der Nordsee: Okologie einer borealen Brackwasser-Lebensgemeinschaft. Microfauna Marina 3: 81 - 156.","An der Lan H. & Franz H. 1954. Turbellaria. In: Franz H. (ed.) Die Nordost-Alpen im Spiegel ihrer Landtierwelt: 129 - 134. Universitatsverlag Wagner, Innsbruck."]}

Simple Summary Species richness in open water areas is generally lower than in coastal zones. Fish parasites have been targeted as biological tags potentially magnifying biological patterns of their hosts including long-distance migrations notoriously difficult to trace. Lake Tanganyika (Africa) is an ideal place to study general mechanisms of host-parasite interactions in an open water environment and Cichlidogyrus, a monogenean flatworm lineage also present in Lake Tanganyika, has been proposed as a model system to study parasite-host relationships. The present study revealed the lake-wide occurrence (600 km) of Cichlidogyrus casuarinus, a parasite with a broad host range infecting pelagic fishes endemic to Lake Tanganyika. Our comparative approach highlighted incongruence between morphological and genetic differentiation of the populations of Cichlidogyrus casuarinus. Our results show a limitation of the parasite's magnifying potential for the focal host species due to the parasites' broad host range including highly mobile host species. Using different sequencing technologies, the study further provides the first assessment of the genetic variation of mitochondrial data in Cichlidogyrus showing contrasting patterns within and between parasite species. Given the now considerable baseline knowledge on its morphological and genetic variation, we propose C. casuarinus as a model to study (1) mechanisms driving host range and (2) the role of phenotypic plasticity in diversification and speciation. Little phylogeographic structure is presumed for highly mobile species in pelagic zones. Lake Tanganyika is a unique ecosystem with a speciose and largely endemic fauna famous for its remarkable evolutionary history. In bathybatine cichlid fishes, the pattern of lake-wide population differentiation differs among species. We assessed the congruence between the phylogeographic structure of bathybatine cichlids and their parasitic flatworm Cichlidogyrus casuarinus to test the magnifying glass hypothesis. Additionally, we evaluated the use of a PoolSeq approach to study intraspecific variation in dactylogyrid monogeneans. The lake-wide population structure of C. casuarinus ex Hemibates stenosoma was assessed based on a portion of the cox1 gene combined with morphological characterisation. Additionally, intraspecific mitogenomic variation among 80 parasite samples from one spatially constrained metapopulation was assessed using shotgun NGS. While no clear geographic genetic structure was detected in parasites, both geographic and host-related phenotypic variation was apparent. The incongruence with the genetic north-south gradient observed in H. stenosoma may be explained by the broad host range of this flatworm including eupelagic bathybatine host species that form panmictic populations across the lake. In addition, we present the first parasite mitogenome from Lake Tanganyika and propose a methodological framework for studying the intraspecific mitogenomic variation of dactylogyrid monogeneans. Czech Science Foundation (GAR) [P505/12/G112, GA19-13573S]; Research Foundation-Flanders (FWO-Vlaanderen)FWO [1513419N]; stand-alone project of the Austrian Science Fund (FWF) [P 32691]; European Marine Biological Research Centre (EMBRC) Belgium; FWO-Vlaanderen projectFWO [GOH3817N]; Special Research Fund of Hasselt University [BOF20TT06]; project "e-Infrastruktura CZ" [LM2018140]

Cheliplana varicauda Brunet, 1971 Material examined. Reference material. 2 whole mounts (SMNH 82471–82472) and 1 serially sectioned specimen (SMNH Type 3034). Known distribution. Bay of Valdibora, Rovinj, Croatia (Brunet 1971). Golfe de Marseille, France (Brunet 1971). Remarks. Our observations correspond to those of Brunet (1971). Live specimens appear orange-pink. The caudal region is conspicuous and highly extensible, similar to the situation in Cheliplana sarnensis. Near the caudal body end, a single, continuous adhesive girdle is present. A pair of seminal vesicles and prostatic glands empty into the proximal end of the elongate copulatory bulb and form an elongate prostatic vesicle. A long, curved ejaculatory duct is present, which distally becomes a sclerotised cirrus, armed with fine spines. Longitudinal muscles surround the copulatory bulb. Circular muscles were not observed. The copulatory organ opens into a small male atrium, which immediately connects to a common genital atrium. The latter receives the female atrial organs and a large, globular mass of lightly coloured (eosinophilic) glands. Coarse-grained, basophilic cement glands also empty into the common genital atrium close to the gonopore. The opening of the vagina externa is located a short distance posterior to the gonopore. The vaginal walls are sinuous and muscular, clearly surrounded by longitudinal muscles. The vaginal opening can be closed with a sphincter. Proximally, the vagina leads on into a large, syncytial and poorly delineated bursa, which shows large vacuoles containing sperm. Three sclerotised spermatic ducts connect the bursa to the large ovary, situated alongside the male copulatory apparatus and the bursa., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 485, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1971) Cheliplana varicauda n. sp., nouveau turbellarie calyptorynque de la famille des Karkinorhynchidae. Annales de l'Universite ' de Provence-Sciences, 45, 25 - 28."]}

Cheliplana setosa Evdonin, 1971 Fig. 9A–D Material examined. New material. CANADA • 1 whole mount; British Columbia, Calvert Island, Foggy Cove; 51°39’07”N, 128°08’32”W; 9 Apr. 2016; medium-grained sand in between boulders in the lower intertidal; MI4193 • 1 whole mount; British Columbia, Bamfield, Brady Beach; 48°49’40”N, 125°09’12”W; 3 Jun. 2015; mediumgrained sand in lower intertidal; MI4194. Reference material. 1 whole-mounted specimen (SMNH 90403) and 1 serially sectioned specimen (SMNH 102990) from California, United States. Known distribution. Posyet, Peter the Great Gulf, Russia (Evdonin 1977). Monterey Bay, California, United States (Karling 1983). Ría de Villaviciosa, near San Martin, Spain (Noreña et al. 2007). Remarks. Live specimens are ~ 1.5 mm long. Specimens are yellowish to pinkish in colour (Fig. 9A). The proboscis bears curved proboscis hooks measuring 18–20 μm (h, Fig. 9C). Hook supports are about 12 μm long in the specimens from Canada (hs, Fig. 9C). Rod-shaped, weakly sclerotised proboscis sidepieces were observed by Karling (1983). The prepharyngeal tube is armed with spines (ppc, Fig. 9A). A single, large testis is situated alongside the pharynx (ph, t, Fig. 9A). Karling (1983) reports a lobe containing sperm at the posterior end of the testis. A pair of seminal vesicles, one of which ending blindly, the other connecting to the testis via an unpaired vas deferens, enter the proximal end of the copulatory bulb (cb, vs, Fig. 9A–B,D). The copulatory bulb is oviform (cb, Fig. 9A–B,D). In the Russian specimens, Evdonin (1971) measures a size range of 110 to 120 μm for the copulatory bulb. The Californian specimen described by Karling (1983) possesses a copulatory bulb of ~130 μm. The copulatory bulbs in the new specimens from Canada are somewhat larger still, measuring 130–160 μm. The copulatory bulb holds a cirrus of 40–60 μm (Russia and California) (Evdonin 1971; Karling 1983) or 68–85 μm (Canada) (ci, Fig. 9 A–B,D). The cirrus can be divided in three clearly defined regions: (1) a proximal tube-like region of ~48 μm (California) to 48–60 μm (Canada), armed with fine spines, (2) a ring of five or six large spines of about 10–15 μm (Canada) long, set in sclerotised pockets, and (3) a distal region of ~7 μm (California) to 15–17 μm (Canada) long, wider than the proximal region, armed with hair-like spines. A single ovary (ov, Fig. 9A) and bursa are situated near the caudal body end., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 480-482, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Evdonin, L. A. (1971) The interstitial Kalyptorhynchia (Turbellaria, Neorhabdocoela) from the bay of Peter the Great of the Sea of Japan. Akademii Nauk SSSR Issledovanija Fauna Morei, 8 (16), 55 - 71.","Karling, T. G. (1989) New taxa of Kalyptorhynchia (Platyhelminthes) from the N. American Pacific coast. Zoologica Scripta, 18 (1), 19 - 32. https: // doi. org / 10.1111 / j. 1463 - 6409.1989. tb 00120. x","Evdonin, L. A. (1977) Monograph of the Turbellaria Kalyptorhynchia in the fauna of the USSR and adjacent areas. Fauna USSR, Turbellaria, 1 (Pt. 1.), New Series, 115, 1 - 400.","Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x","Norena, C., Damborenea, C., Faubel, A. & Brusa, F. (2007) Composition of meiobenthonic Platyhelminthes from brackish environments of the Galician and Cantabrian coasts of Spain with the description of a new species of Djeziraia (Polycystididae, Kalyptorhynchia). Journal of Natural History, 41 (29 - 32), 1989 - 2005. https: // doi. org / 10.1080 / 00222930701526055."]}

Cheliplana asinaraensis n. sp. Gobert, Reygel & Artois Fig. 1A–B Etymology. The species epithet ‘asinaraensis’ refers to the National Park of Asinara (Sardinia, Italy), where the specimen was found. Material examined. Holotype. ITALY • 1 whole mount; Punta Tumbarino, Asinara National Park, Sardinia; 41°02’17”N, 08°13’13”E; 29 Sep. 2014; 29 m depth, coarse gravel with silt from a channel among rocks; KV.633. Description. The specimen is ~ 1.5 mm long, transparent and colourless. The proboscis is large, with an overall length of ~50 μm (p, Fig. 1A). The hook supports measure ~20–22 μm, and the smooth, evenly curved proboscis hooks measure ~38 μm. The mouth is situated ventrally, posterior to the proboscis, and is connected to the pharynx via a long, unarmed oral tube. The anterior edge of the pharynx is lined with papillae. A single testis is positioned alongside the pharynx (t, Fig. 1A). The common genital opening is situated in the posterior 1/5 of the body and is surrounded by glands (gp, Fig. 1A). The atrial organs of the male and female genital system surround the gonopore. The male copulatory system consists of a pair of relatively large seminal vesicles (vs, Fig. 1A), which enter the elongate copulatory bulb proximally. At the same location, a large group of prostatic glands enter the bulb and form a prostatic vesicle in the proximal half of the copulatory bulb (pg, Fig. 1A). The distal half of the ejaculatory duct forms a sclerotised cirrus with an overall length of 60 μm (ci, Fig. 1A; Fig. 1B). The cirrus consists of two clearly defined regions (Fig. 1B). The proximal part is a sclerotised, straight tube, which shows a longitudinal striation. Towards the distal end of this part, fine triangular spines are present. The distal, 18- μm-long part of the cirrus is crescent-shaped and eccentrically curved. The outer part of the crescent is armed with very fine, bristle-like spines, while in the central part, large, but thin lamellae are present. A large ovary is positioned adjacent to the male copulatory system (ov, Fig. 1A). An oviduct or ductus communis could not be observed. A vaginal opening is situated medioventrally, directly anterior to the adhesive girdle. The vagina externa is surrounded by longitudinal or diagonal muscles. Circular muscles may be present as well, but this was impossible to ascertain from the whole-mounted specimen. A constriction separates the vagina from a large, sac-like bursa (b, Fig. 1A). The proximal end of the bursa shows a small, globular part, provided with a small, funnel-shaped spermatic duct., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 457, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692

Cheliplana asica Marcus, 1952 Material examined. Reference material. 1 whole mount and 3 serially sectioned specimens from Brazil (SMNH 109332–109335) Known distribution. São Paulo, Brazil (Marcus 1952). Holguín, Cuba (Diez et al. 2019). Remarks. Based on differences in cirrus morphology and the bursa-ovary connection, Brunet (1968) divided Cheliplana asica in two subspecies, C. asica asica from Brazil and C. asica terminalis from the Mediterranean and West Indian Ocean. We now consider both subspecies to be separate species (see remarks on C. terminalis Brunet, 1968). Our observations on the Brazilian species correspond to Marcus’ description (Marcus 1952) and the notes by Brunet, 1968. Live specimens are ~ 1.8 mm long, with a single, caudal adhesive belt. The proboscis is armed with 12–15-µmlong hooks and provided with a pair of short, sclerotised sidepieces. The postrostral bulb measures 30 μm by 10 μm and is surrounded by circular muscles. The prepharyngeal tube is lined with an epithelium forming microvilli. The pharynx is characterised by papillae on its rostral edge. The single testis is positioned ventro-caudally to the pharynx. A pair of efferent ducts leads from the testis to a pair of spindle-shaped seminal vesicles, which in turn enter the proximal end of a slender copulatory bulb along with prostatic glands. The proximal end of the copulatory bulb is ~12 μm wide and is bordered by a high epithelium. The entire copulatory apparatus is ~280 μm long. The ejaculatory duct forms a long, unarmed, sclerotised cirrus., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 465, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Marcus, E. (1952) Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo, 17, 5 - 188.","Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1","Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana hawaiiensis n. sp. Gobert, Reygel, Van Steenkiste & Artois Fig. 2A–C, Fig. 3A–C, Fig. 4 Etymology. The species epithet refers to the Hawaiian archipelago, where the species was first found. Material examined. Holotype. UNITED STATES • 1 whole mount; Hawaii, Oahu, Waimanalo Beach; 21°19’36”N, 157°40’59”W; 31 May 2010; intertidal zone, fine sand with organic detritus among blocks of coral; KV.635. Other material. UNITED STATES • 6 whole mounts and two serial sections; Hawaii, Oahu, Waimanalo Beach; 21°19’36”N, 157°40’59”W; 31 May 2010; intertidal zone, fine sand with organic detritus among blocks of coral; HU X.2.26–X.2.33. CANADA • 3 whole mounts; British Columbia, Calvert Island, West Beach; 51°39’24”N, 128°08’41”W; 3 Jun. 2015; intertidal zone, medium-grained sand from the beach surface; MI4186–MI4188 • 3 whole mounts; British Columbia, Calvert Island, North Beach; 51°39’52”N, 128°08’46”W; 7 Jun. 2017; coarse sand in lower intertidal; MI4189–MI4191 • 1 whole mount; British Columbia, Calvert Island, Foggy Cove; 51°39’07”N, 128°08’32”W; 9 Apr. 2016; medium-grained sand in between boulders in the lower intertidal; MI4192. Description. Specimens are largely transparent, with a weak brown to orange colouration (Figs. 3A, 4A). A caudal haptic girdle is present (ag, Fig. 2A). The proboscis of the Hawaiian specimens is ~37 μm long with 18-μmlong muscular hook supports and a pair of smooth proboscis hooks ~20 μm long (h, hs, Fig. 3B). The proboscis of the Canadian specimens is about 28 μm long with 10-μm-long hook supports and 18 μm long hooks (h, hs, Fig. 4B; 4D). The proboscis sidepieces are straight, non-sclerotised rods, with enlarged distal ends, bearing a single bristle (sp, Figs. 3B; 4B). The mouth is situated directly posterior to the proboscis. The pharynx is positioned in the anterior part of the body (ph, Figs. 2A; 3A; 4A) and connects to the mouth via a long, slender oral cavity lined with spines (ppc, Fig. 2A; 4A). The anterior edge of the pharynx is lined with papillae. In some specimens, the body contains large numbers of diatom frustules. A single testis is present in the anterior body half, just behind and/or alongside the pharynx (t, Fig. 2A; 3A; 4A). The posterior part of the testis shows a globular accumulation of sperm, probably corresponding to the area where the testis connects to the vas deferens. The male copulatory bulb measures ~117 μm in the Hawaiian specimens (cb, Fig. 3A) and 75–100 µm in the Canadian specimens (cb, Fig. 4A,C,E). Two seminal vesicles enter the copulatory bulb proximally (vs, Figs. 2A; 4A,C). The copulatory bulb is of the conjuncta duplex type (Karling 1956) and is surrounded by a sheath of longitudinal muscles. The presence of circular muscles surrounding the copulatory bulb could not be determined. The large prostatic glands also enter the copulatory bulb proximally and form a prostatic vesicle in the proximal part of the bulb (pg, vg, Figs. 2A; 3A; 4A,C). The distal part of the bulb holds the ejaculatory duct, the distal end of which forms an armed cirrus (Figs. 2C; 3C; ci, Figs. 2A; 3A; 4A,C,E) measuring 30–40 μm (Canada) or 41–68 μm (Hawaii). The cirrus is differentiated in three distinct regions (Figs. 2C; 4E): the most proximal part is tubular, with a length of 15–31 μm (x = 21 μm, n = 6; Hawaii) or 12–18 μm (x = 15 μm, n = 7; Canada) and a diameter of 8–16 μm (x = 12 μm, n = 6; Hawaii) or 7–9 μm (x = 8 μm, n = 7; Canada). This part is armed with very fine spines with a rectangular base. This proximal tube is followed distally by a ring of six long, curved spines of ~12 μm long (measured on Canadian specimens), each set in sclerotised pockets. The most distal region is 23–34 μm (x = 27 μm, n = 6; Hawaii) or 12–17 μm (x = 15 μm, n = 7; Canada) long, with a diameter of ~17–26 μm (x = 22 μm, n = 6; Hawaii) or 12–17 μm (x = 14 μm, n = 7; Canada). This distal part is lined with densely stacked, bristle-like spines with a length of ~8 μm (Hawaii) or ~5 μm (Canada). A single, large ovary is present near the copulatory apparatus (ov, Fig. 4A). A bursa is situated posterior to the common genital opening (b, Fig. 4A,C). No spermatic duct or vagina externa were observed., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 459-461, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Karling, T. G. (1956) Morphologisch-histologische Untersuchungen an den mannlichen Atrialorganen der Kalyptorhynchia (Turbellaria). Arkiv for Zoologi, Serie 2, Band 9 (7), 187 - 279."]}

Cheliplana gibarenha Diez, Reygel & Artois, 2019 Material examined. None. Known distribution. Gibara, Cuba (Diez et al. 2019). Remarks (summarised from literature).Whole-mounted specimens are ~ 0.8 mm long.The body is transparent. The proboscis has a pair of muscular hook supports (5 µm) and 14-µm-long, curved hooks. The mouth opens just caudally from the postrostral bulb. The pharynx is slightly shorter than the spiny prepharyngeal cavity. The single testis lies next to the pharynx and is connected to a single, caudally positioned seminal vesicle (184 µm x 28 µm) through a very long vas deferens. The copulatory bulb is directed forward and comprises an elongate prostate vesicle and the cirrus (140 µm x 4 µm). The distal 13 µm of the cirrus is armed with small spines (0.5 µm). The distal part of the copulatory bulb is characterised by a strong sphincter surrounding the cirrus. The single ovary is positioned near the transition between the seminal vesicle and prostate vesicle. Oocytes lie in a row and proximally decrease in diameter. The caudally positioned bursa appears bipartite and opens caudally into the vagina., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 473, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1"]}

Cheliplana curini Gobert, Reygel & Artois, 2017 Material examined. Reference material. 9 whole-mounted specimens, including the holotype (SMNH Type 8905; VII.4.29– VII.4.36), and 8 serially sectioned specimens (HU VII.4.37– VII.4.44) from Lanzarote and Sardinia. Known distribution. Lanzarote, Canary Islands, Spain (Gobert et al. 2017). Sardinia, Italy (Gobert et al. 2017). Remarks. Live specimens are ~ 0.8–1.3 mm long, with orange to bright red pigmentation. The proboscis is ~40 μm long, with smooth hooks measuring 20–27 μm and hook supports of ~20–30 μm. A pair of soft, rod-shaped proboscis sidepieces, without bristles, is present. The horizontally oriented pharynx measures approximately 1/5 of the total body length and connects to the mouth via a long, unarmed prepharyngeal tube. A single testis is positioned near the caudal end of the pharynx. In the posterior half of the body, an elongate copulatory bulb (350–370 μm) is present. A pair of seminal vesicles enters the proximal end of the copulatory bulb, which contains a globular prostatic vesicle. A long ejaculatory duct runs axially through the copulatory bulb. Distally, it forms a sclerotised, unarmed cirrus (56–74 μm) surrounded by three blind-ending accessory cirri. The latter respectively measure 43–50 μm, 50–80 μm and 60–75 μm. Each accessory cirrus is provided with fine spines. The cirrus and accessory cirri merge into a thinly sclerotised, unarmed ‘sleeve’, which makes up a distal penis papilla. A muscular vagina externa opens caudally to the gonopore. The interior lumen of the vagina is lined with a thickened basal lamina, forming a pseudo-cuticula. The vagina connects to a large bursa that consists of two parts: a non-muscular, syncytial region, containing large vesicles adjacent to the ovary, and a distal, saclike region. No spermatic duct between the ovary and bursa is present., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 467, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Gobert, S., Reygel, P. & Artois, T. (2017) Schizorhynchia (Platyhelminthes, Rhabdocoela) of Lanzarote (Canary Islands), with the description of eight new species. Marine Biodiversity, 49 (5), 2089 - 2107. https: // doi. org / 10.1007 / s 12526 - 017 - 0736 - x."]}

Cheliplana remanei (Meixner, 1928) Karling, 1983 Fig. 8A–B Synonyms. Rhinepera remanei Meixner, 1928. Material examined. New material. GERMANY • 2 whole mounts; Sylt, beach south of List harbour; 55°00’55”N, 6°26’11”E; 28 Apr. 2015; spot with algae and somewhat coarser sediment than the surrounding silt; HU X.2.41– X.2.42. Note. No reference material was available to us at the time of this study Known distribution. Strander Bay, Germany (Meixner 1928). Kiel Bay, Germany (Meixner 1928; Schmidt 1972). Sylt, Germany (Hellwig 1987; Scherer 1985; Noldt 1989). Römö, Denmark (Schilke 1970). Eastern Scheldt, the Netherlands (Martens & Schockaert 1981). Remarks. Meixner (1928) reports an average body length of 0.72 mm, measured on multiple fixed specimens. Live specimens are colourless.A single, continuous caudal haptic girdle is present subterminally.The small proboscis is armed with a pair of smooth, curved hooks, measuring ~18 μm (Meixner 1928) (17–21 μm in our specimens). A pair of soft proboscis sidepieces has been reported, projecting from the base of the muscular hook supports and bearing a 10–12-µm-long bristle (Meixner 1928; Noldt 1989). We did not observe the sidepieces in the newly collected material. The postrostral bulb measures approximately three times the length of the proboscis. The cylindrical pharynx is situated in the anterior third of the body and connected to the mouth via a long prepharyngeal cavity. The interior surface of the prepharyngeal cavity is lined with 4–7 μm-long sclerotised spines, organised in 5 longitudinal rows according to Meixner (1928). Noldt (1989) counted 8–10 rows of spines, measuring 8–11 μm. We were unable to count the spine rows in the newly collected specimens. A single, large testis is situated alongside the posterior end of the pharynx. An unpaired seminal vesicle enters the proximal end of the copulatory bulb (cb, vs, Fig. 8B). The bulb is entirely packed with parenchymatic tissue (Noldt 1989) and surrounded by a layer of longitudinal muscles. A prostatic vesicle is present in the proximal part of the bulb (vg, Fig. 8B), surrounding the ejaculatory duct. According to Noldt (1989), the prostatic glands empty into the ejaculatory duct near the base of the cirrus. The cirrus is curved and consists of a short, proximal, unarmed, ring-like region (10–12 μm long according to Noldt (1989); 10–21 μm in our specimens, n = 2), followed by a curved, asymmetrical part, armed with bristle-like spines (85–110 μm long according to Noldt (1989); 118–142 μm in our specimens, n = 2) (ci, Fig. 8A–B). The spines are maximally 9 μm long. At the distal end, the cirrus is unarmed and partially everted to form a sclerotised penis papilla that protrudes into the male atrium (pp, Fig. 8A–B). In the newly collected specimens from Sylt, the penis papilla measures 20–34 μm (n = 2), though this length likely depends on the contraction state of the copulatory apparatus. Noldt (1989) reports a diameter of 18–25 μm for the penis papilla. Noldt (1989) presents no information on the female genital tract. In our specimens, a single large ovary is visible posterior to the male copulatory bulb. A bursa lies adjacent to the ovary. No vagina (interna or externa) or spermatic duct between the bursa and ovary was observed., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 478-479, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Meixner, J. (1928) Aberrante Kalyptorhynchia (Turbellaria Rhabdocoela) aus dem Sande der Kieler Bucht. Zoologischer Anzeiger, 77, 229 - 253.","Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x","Schmidt, P. (1972) Zonierung und jahreszeitliche Fluktuationen des Mesopsammons im Sandstrand von Schilksee (Kieler Bucht). Mikrofauna Meeresbodens, 10, 1 - 60.","Hellwig, M. (1987) Oekologie freilebender Plathelminthen im Grenzraum Watt-Salzwiese lenitischer Gezeitenkusten. Microfauna Marina, 3, 157 - 244.","Scherer, B. (1985) Annual dynamics of a meiofauna community from the \" sulfide layer \" of a North Sea sand flat. Microfauna Marina, 2, 117 - 162.","Noldt, U. (1989) Kalyptorhynchia (Plathelminthes) from sublittoral coastal areas near the island of Sylt (North Sea) I. Schizorhynchia. Microfauna Marina, 5, 7 - 85.","Schilke, K. (1970) Kalyptorhynchia (Turbellaria) aus dem Eulitoral der deutschen Nordseekuste. Helgolander wissenschaftliche Meeresuntersuchungen, 21, 143 - 265. https: // doi. org / 10.1007 / BF 01630522","Martens, P. M. & Schockaert, E. R. (1981) Sand dwelling Turbellaria from the Netherlands Delta area. Hydrobiologia, 84, 113 - 127. https: // doi. org / 10.1007 / BF 00026169","Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440."]}

Cheliplana targa (Marcus, 1952) Karling, 1983 Synonyms. Rhinepera targa Marcus, 1952 Known distribution. Bay of Santos, Brazil (Marcus 1952). Material examined. None. Remarks (summarised from literature). Marcus (1952) describes C. targa as a small species (0.3–0.9 mm total body length). A single testis is located ventrally, at the caudal end of the pharynx. A single efferent duct leads from the caudal end of the testis towards a seminal vesicle, which enters the proximal end of the copulatory bulb. The copulatory bulb is thick-walled, surrounded by a sheath of longitudinal muscles and contains a prostatic vesicle in its proximal part., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 483, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Marcus, E. (1952) Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo, 17, 5 - 188.","Karling, T. G. (1983) Structural and systematic studies on Turbellaria Schizorhynchia (Platyhelminthes). Zoologica Scripta, 12 (2), 77 - 89. https: // doi. org / 10.1111 / j. 1463 - 6409.1983. tb 00552. x"]}

Cheliplana californica Karling, 1989 Fig. 9E Material examined. New material. CANADA • British Columbia, Vancouver, Wreck Beach; 49°15’48”N, 123°15’46”W; 10 Apr. 2015; 1 whole mount; superficial sediment with coarse fraction near rocky headland in the lower intertidal; MI4181. Reference material. 2 whole mounts, including the holotype, and 1 serially sectioned specimen from California (SMNH Type 6799; SMNH 90402). Known distribution. Elkhorn Slough, Monterey Bay, California, United States (Karling 1989). Remarks. Our observations correspond to the original description by Karling (1989). Specimens are ~ 1 mm long and colourless. The caudal haptic girdle is described as consisting of approximately 40 papillae. The cylindrical pharynx is connected to the mouth through a long prepharyngeal tube lined with hair-like bristles. A pair of testes lies alongside the pharynx and the two testes are connected to each other across the oral tube. The oviform male copulatory bulb measures ~95 μm in the Canadian specimen (cb, Fig. 9E) and 118–123 μm in specimens from California (n = 2). The copulatory bulb encloses a short ejaculatory duct, which distally continues in an asymmetrically armed cirrus (ci, Fig. 9E). The cirrus in the specimen from Canada is smaller (~30 μm) compared to the cirrus in Californian specimens (43–47 μm, n = 2). The cirrus spines measure 4–10 μm, increasing in length towards the distal end on one side, while decreasing in length towards the distal end on the other side. Distally, the cirrus ends in a short, sclerotised tube, which may be everted to form a cylindrical papilla. The yolk glands are paired. A non-muscular vagina externa is present, with the opening lying directly anterior to the gonopore. The external vagina opens into a large bursa, which is connected to the single ovary through a spermatic duct., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 466, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Karling, T. G. (1989) New taxa of Kalyptorhynchia (Platyhelminthes) from the N. American Pacific coast. Zoologica Scripta, 18 (1), 19 - 32. https: // doi. org / 10.1111 / j. 1463 - 6409.1989. tb 00120. x"]}

Cheliplana terminalis Brunet, 1968 Fig. 8C–D Synonyms. Cheliplana asica terminalis Brunet, 1968 Material examined. New material. AUSTRALIA • 2 whole mounts; Port Lincoln, Coffin Bay, Kellidie Bay; 34°36’41”S, 13°31’03”E; 8 Dec. 2010; along turn-off to airstrip, coarse-grained sand and shell gravel; HU X.2.02– X.2.03. FRANCE • 1 whole mount; Cerbère, Terrimbo; 19 Jul. 2007; mixture of fine and coarse sand, fairly clean with little silt, from within the bay at a depth of 8 m; HU VIII.4.28 • 1 whole mount; Cerbère, Terrimbo, Les Aloès; 27 Jul. 2012; directly in front of the scaffold, 50 m into the sea, fine sand from a depth of 6 m; HU VIII.4.29 • 2 whole mounts; Canet-en-Rousillon, Canet-Plage; 31 Aug. 2016; pure, fine sand from beach in front of parking harbour, from a depth of 0.5 m; HU VIII.4.36 & HU VIII.4.38 • 3 whole mounts; Canet-en-Rousillon, Canet-Plage; 31 Aug. 2016; pure, fine sand from bend in beach, from a depth of 0.4 m; HU VIII.4.37 & HU VIII.4.39–HU VIII.4.40. SPAIN • 1 whole mount; Catalonia, Blanes; 20 Jul. 2012; sand patches from the north side of a rock with footpath; coarse, clean sand with vegetal debris from a depth of 3 to 4 m; HU VIII.4.34. Reference material. Two serially sectioned specimens from France, one of which the holotype (SMNH Type 2816, SMNH 82468). Known distribution. Provence-Alpes-Côte d’Azur, France (Brunet 1968). Djezira, Mogadishu, Somalia (Schockaert 1982). Mombasa, Kenya (Jouk & De Vocht 1989). Santiago de Cuba and Chivirico, Cuba (Diez et al. 2019). Remarks. According to Brunet’s (1968) description, live specimens are pink and measure ~ 1.6 mm. The proboscis hooks reach a length of 15–16 μm. The copulatory organ is highly similar to that of C. asica as described by Marcus (1952), but differs in the sclerotised distal end of the cirrus (Fig. 8C–D) and the sclerotised penis papilla that surrounds it (pp, Fig. 8C–D). The female system also exhibits a number of differences. According to Brunet (1968), the bursa in C. terminalis connects to the ovary via a well-differentiated spermatic duct provided with a small sclerotised piece, while in C. asica, the bursa connects to the female genital duct (ductus communis). While we were unable to confirm the bursa-female duct connection on material of C. asica, we would argue that the above-mentioned features of the male and female system, if correctly observed, are differential diagnostic characters. As such, we consider C. terminalis and C. asica two separate species. The specimens collected from Somalia and described by Schockaert (1982) likely belong to C. terminalis, because of the presence of a sclerotised penis papilla and the greater degree of sclerotisation of the distal end of the cirrus (compared to Marcus’ (1952) description of C. asica). However, it should be noted that without additional information on the female system, the identification of these specimens as C. terminalis is somewhat tenuous. Furthermore, the specimens from Somalia are substantially smaller than the size ranges described by Brunet (1968). The new specimens from Australia fall more or less within the size range reported by Brunet (1968) and share the long, sclerotised and largely unarmed cirrus with a distal, sclerotised penis papilla. The characters of the female system, however, were not observed., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 483-484, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Brunet, M. (1968) Turbellaries Karkinorhynchidae de la region de Marseille. Les genres Cheliplana et Cheliplanilla. Cahiers de Biologie Marine, 9, 421 - 440.","Schockaert, E. R. (1982) Turbellaria from Somalia. II. Kalyptorhynchia (part 2). Monitore Zoologico Italiano, 17, 81 - 96. https: // doi. org / 10.1080 / 03749444.1982.10736660","Jouk, P. E. H. & De Vocht, A. J. - P. (1989) Kalyptorhynchia (Plathelminthes Rahbdocoela) from the Kenyan Coast, with description of four new species. Tropical Zoology, 2, 145 - 157. https: // doi. org / 10.1080 / 03946975.1989.10539435.","Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1","Marcus, E. (1952) Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo, 17, 5 - 188."]}

Cheliplana verrucosa Diez, Reygel & Artois, 2019 Material examined. None. Known distribution. Bueycabón, Cuba (Diez et al. 2019). Remarks (summarised from literature). Live specimens are pinkish in colour and ~ 0.7 mm long. The epidermis is covered in wart-like glands, except for the caudal 20% of the body. Small, rounded rhabdites are present across the entire body. The proboscis hooks (15–16 μm) are bifurcate at the tip, forming a second, smaller hook of 5–6 μm. The muscular hook supports are 15–17 μm long. The pharynx measures 1/9 to 1/8 of the total body length and is connected to a spiny, elongated prepharyngeal cavity. The latter is three times longer than the pharynx. The single testis lies ventro-laterally to the pharynx and connects to a single seminal vesicle, which proximally empties into the copulatory bulb. Prostate glands enter the copulatory bulb at approximately the same place. The inverted-pear shaped copulatory bulb (49 µm) comprises the prostate vesicle and a spiny, 28-µm-long, arrow-like cirrus: proximally, the cirrus is 9 µm wide, it narrows to 4 µm at its midpoint, widens again to 12 µm subdistally and finally narrows to a distal, triangular tip. Cirrus spines are largest in the proximal end (7–9 µm) and distally decrease to 4–5 µm. The vitellarium extends from the pharynx to the copulatory bulb. A single, kidney-shaped ovary and globular bursa are positioned in the caudal body end. Oocytes are organised in a row and proximally decrease in diameter. A connection between the bursa and common atrium is visible., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 486, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Diez, Y. L., Reygel, P. & Artois, T. (2019) Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species. Zootaxa, 4646 (1), 1 - 30. https: // doi. org / 10.11646 / zootaxa. 4646.1.1"]}

Cheliplana longissima n. sp. Gobert, Reygel & Artois Figs. 2F–H, 3D–E Etymology. The species epithet ‘longissima’ refers to the very long cirrus. Material examined. Holotype. PANAMA • 1 whole mount; Isla de Taboga, Playa de la Isla Taboga; 8°48’05”N, 79°33’16”W; 9 Dec. 2011; intertidal, medium fine to medium coarse sand from ripple marks in between Caulerpa and close to swash zone; KV.665. Other material. PANAMA • 3 whole mounts (incl. one juvenile specimen) and 3 serial sections; Isla de Taboga, Playa de la Isla Taboga; 8°48’05”N, 79°33’16”W; 9 Dec. 2011; intertidal, medium fine to medium coarse sand from ripple marks in between Caulerpa and close to swash zone; HU X.2.34–X.2.39. Description. Live specimens are transparent to slightly pink in colour.The body is 0.9–1.0 mm long, as measured on squeezed, whole-mounted specimens. A continuous haptic girdle is present at the caudal body-end (ag, Fig. 2H). The proboscis bears a pair of 15–23-μm-long (x = 19 μm, n = 4), curved hooks (h, Fig. 2G). The hook supports are relatively small, measuring 9–10 μm (hs, Fig. 2G). The mouth is situated a short distance behind the proboscis and is connected to the cylindrical pharynx through a long prepharyngeal tube (ph, ppc, Fig. 3E). The epithelium lining the inside of the tube is differentiated to form long, finger-like papillae lining the entire surface of the tube. These papillae do not appear to be sclerotised. Some diatom frustules were observed in the digestive tract. The common genital opening is situated in the posterior quarter of the body and is surrounded by glands (gl, gp, Fig. 2H). Two small, elongate seminal vesicles are provided with longitudinal muscles and enter the copulatory bulb proximally. The copulatory bulb (cb, Figs. 2H; 3D,E) is elongate and contains a prostatic vesicle in its proximal third (vg, Figs. 2H; 3D), followed distally by a long ejaculatory duct and a long, armed cirrus (ci, Figs. 2F,H; 3D,E). A thick layer of longitudinal muscles and circular muscles surrounds the copulatory bulb. The inside wall of the copulatory bulb shows a series of thin transverse crests on the dorsal side of the bulb (Fig. 2H). The interior surface is lined with a thin epithelium. The cirrus measures 235–365 μm (x = 300 μm, n = 2) and is armed with very fine spines (ci, Figs. 2F,H; 3D,E). In all available specimens, a characteristic loop was observed in the proximal part of the cirrus (ci, Figs. 2F,H; 3D). Distally, the cirrus ends in a short, sclerotised penis papilla (pp, Fig. 2F; 3D). The vaginal opening is located terminally and can be closed by a sphincter. It opens into an elongate vagina externa (ve, Fig. 2H), the distal end of which is surrounded by circular muscles. The vagina externa connects to the bursa, which is not muscular (b, Fig. 2H). The bursal lumen is lined with a pseudo-cuticular lining and surrounded by a thick, apparently syncytial parenchymatic tissue. The proximal end of the bursa is globular, nearly spherical, and lies adjacent to the single ovary, on the right-hand side of the body (ov, Fig. 2H). The quality of the sections did not allow study of any further details of the female system, such as a possible connection between the ovary and bursal complex and between the ovary and common genital atrium/gonopore. A number of conspicuous nuclei are present at the proximal end of the bursa (Fig. 2H).

Cheliplana canariensis Gobert, Reygel & Artois, 2017 Material examined. Reference material. The holotype, a whole-mounted specimen from Lanzarote (SMNH Type 8906). Known distribution. Lanzarote, Canary Islands, Spain (Gobert et al. 2017). Remarks. The specimen is rather small, with a total body length of 0.6 mm. The proboscis is ~42 μm long and carries 27–28-µm-long, curved hooks and ~18-μm-long hook supports. The paired seminal vesicles separately enter the proximal end of the copulatory apparatus. The copulatory bulb holds a proximal, prostatic bulb. Distally, the ejaculatory duct is differentiated into a 50-µm-long cirrus, armed with spines of varying length and thickness. The spines in the middle region of the cirrus are more robust and longer than those in the proximal and distal parts of the cirrus. A single ovary and large bursa are present near the caudal end of the body, but the organisation of the female system is not well known., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on pages 466-467, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Gobert, S., Reygel, P. & Artois, T. (2017) Schizorhynchia (Platyhelminthes, Rhabdocoela) of Lanzarote (Canary Islands), with the description of eight new species. Marine Biodiversity, 49 (5), 2089 - 2107. https: // doi. org / 10.1007 / s 12526 - 017 - 0736 - x."]}

Cheliplana orthocirra Ax, 1959 Material examined. New material. ITALY • 1 whole mount; Sardinia, Asinara National Park, Cala del Bianco; 41°04’27”N, 8°20’12”E; 25 Sep. 2014; medium-grained sand between Posidonia sp., at 2.5 m deep; HU X.2.40. Note. No reference material was available to us at the time of this study. Known distribution. Florya, Sea of Marmara, Turkey (Ax 1959). Southern and Western Sweden (Atherton & Jondelius 2020). Remarks. The proboscis hooks are smooth, fairly straight and ~11 μm long in the specimen from Sardinia. Ax (1959) does not give any measurements except those pertaining to the cirrus. Cheliplana orthocirra has a pair of partially fused testes, positioned on one side of the pharynx. The copulatory bulb is positioned in the posterior half of the body and contains a proximal prostatic vesicle, which connects directly to the distal cirrus. A pair of large, globular seminal vesicles and prostatic glands enter the proximal end of the copulatory bulb. The cirrus is armed with very fine spines over its entire length. These spines decrease in size towards the distal end of the cirrus. A single gonopore and bursa are present near the caudal end of the specimen. In the specimen from Sardinia, the cirrus is 35 μm long, which is significantly shorter than the ~56 μm reported by Ax (1959). Nevertheless, given the cirrus shape and generally similar internal morphology, we feel confident in ascribing this specimen to C. orthocirra., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 475, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Ax, P. (1959) Zur Systematik, Okologie und Tiergeographie der Turbellarienfauna in den ponto-kaspischen Brackwassermeeren. Zoologische Jahrbucher Abteilung fur Systematik, Geographie und Biologie der Tiere, 87, 43 - 184.","Atherton, S. & Jondelius, U. (2020) Biodiversity between sand grains: Meiofauna composition across southern and western Sweden assessed by metabarcoding. Biodiversity Data Journal, 8, e 51813. https: // doi. org / 10.3897 / BDJ. 8. e 51813"]}

Cheliplana caeca Meixner, 1938 The name Cheliplana caeca was used by Meixner (1938) to refer to a species of Cheliplana with strongly curved proboscis hooks and a thick ‘cuticle’ lining the prepharyngeal tube. As noted by Marcus (1952), who refrained from including C. caeca in his key to Karkinorhynchidae, both the male and female genital structures are unknown, making it impossible to identify the species in the future. It is therefore considered a nomen nudum., Published as part of Gobert, Stefan, Diez, Yander L., Monnens, Marlies, Reygel, Patrick, Van Steenkiste, Niels W. L., Leander, Brian S. & Artois, Tom, 2021, A revision of the genus Cheliplana de Beauchamp, 1927 (Rhabdocoela: Schizorhynchia), with the description of six new species, pp. 453-494 in Zootaxa 4970 (3) on page 486, DOI: 10.11646/zootaxa.4970.3.2, http://zenodo.org/record/4766692, {"references":["Meixner, J. (1938) Turbellaria (Strudelwurmer). Die Tierwelt der Nord- und Ostsee, 33, 1 - 146.","Marcus, E. (1952) Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo, 17, 5 - 188."]}