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Our current understanding of the human toxicity of plastic particles constitutes a major knowledge gap. MPs can vary largely in their characteristics, and parameters such as size, shape, and chemical composition need to be included in risk assessment strategies. In the present study, we aimed to evaluate the impact of shape on uptake and intracellular effects of MPs comparing both spherical and irregularly shaped polystyrene particles in a human epithelial colorectal adenocarcinoma (Caco-2) cell line. Two sizes of carboxylated polystyrene spheres (200 nm and 2 μm) and self-synthesized irregularly shaped polystyrene particles (average length and diameter: 8.9 μm and 1.14 μm respectively) were used to study on one hand their ability to penetrate cells, and on the other hand their potential to induce changes in metabolic activity, membrane integrity, general reactive oxygen species levels, mitochondrial DNA content and expression of oxidative stress-related genes. Altogether, our study demonstrates that both spheres and irregularly-shaped MPs are internalized by Caco-2 cells in a size-dependent manner, i.e., smaller particles are more easily taken up after 24 h exposure. Intracellularly, a lowering in H2O2 levels was observed for all MPs. This was complemented with mitochondrialchanges after exposure to the 200 nm spheres and irregularly-shaped particles, while differential expression of pro- and anti- oxidative genes, namely HMOX1, CAT and GPX1,was observed during exposure to the 2 μm spheres. These adverse (anti)-oxidative responses indicate that effects are related to the physicochemical and toxicokinetic characteristics of the particles, and highlight the importance of particle characterization to acquire fundamental insights vital for proper hazard profiling.

Additional file 1: Study population. Each year, the ENVIRONAGE birth cohort [29] recruits around 150 singleton births, making it the largest birth cohort with a prospective follow-up in Belgium. Mothers without planned caesarean section and able to fill out a Dutch language questionnaire are eligible for the cohort. We collect biological samples (e.g. placental tissue, cord blood, maternal blood) and have access to all medical records during and after pregnancy, including anthropometric and foetal ultrasound data in addition to lifestyle factors derived from questionnaires filled out after delivery. After birth, we follow these children throughout different stages of life, with a first follow-up visit at the age of 4 – 6 years. During follow-up, we collect biological tissues, lifestyle and medical data, and perform clinical and neurological measurements of both the child and the mother. Measurement of mitochondrial DNA content. DNA was isolated from cord blood buffy coat, containing leukocytes, using the QIAamp DNA mini kit (Qiagen). The relative amount of mtDNA was measured by determining the ratio of two mitochondrial gene copy numbers (MTF3212/R3319 and MT-ND1) to a single-copy nuclear control gene (RPLP0) using a real-time quantitative polymerase chain reaction (qPCR). qPCR reactions were carried out in triplicate on a 384-well plate on the 7900HT Fast Real-Time PCR System (Applied Biosystems) in a 10 μl volume containing: 5 μl Fast SYBR Green (Applied Biosystems) mastermix, 0.3 μl of forward and reverse primers (300 nM) and 1.9 μl RNAse-free water and 6 ng DNA diluted in 2.5 μl RNAse-free water. Primer sequences for mitochondrial genes are reported elsewhere [16]. Six interrun calibrators and no-template controls were included in each qPCR run. The thermal cycling profile for the three targets was 10 min at 95 °C for activation of the polymerase enzyme and initial denaturation, followed by 40 cycles of 15 s at 94 °C for denaturation and 70 s at 58 °C for annealing and extension. After thermal cycling, the raw data were collected and processed using SDS 2.3 software (Applied Biosystems). The cycle quantification (Cq) values were normalized relatively to the RPLP0 gene using qBase + software (Biogazelle) taking into account the run-to-run differences [69]. Supplementary Table S1. Sex- and age-specific BMI cut-offs according to the International Obesity Task Force (IOTF) [30]. Supplementary Table S2. The trimester-specific association between prenatal PM2.5 exposure and childhood overweight (n = 368). Models were adjusted for gestational age, sex, ethnicity, maternal age, socioeconomic status, pre-pregnancy BMI, parity, smoking during pregnancy, and child’s age at follow-up. Trimester-specific estimates of change are given as odds ratio per 5 µg/m³ increment in PM2.5. Childhood overweight was defined based on WHO’s SD BMI scores: > sex- and age-specific BMI cut-offs according to the International Obesity Task Force (IOTF) [30]. Supplementary Table S3. Difference in childhood overweight in association with week-specific prenatal exposure to PM2.5 (n = 368). Models were adjusted for gestational age, sex, ethnicity, maternal age, socioeconomic status, pre-pregnancy BMI, parity, smoking during pregnancy, and child’s age at follow-up. Week-specific estimates of change are given as odds ratio per 5 µg/m³ increment in PM2.5. Supplementary Table S4. The trimester-specific association between prenatal PM2.5 exposure and cord blood MT-ND4L10550A>G heteroplasmy (n = 386). Models were adjusted for gestational age, sex, ethnicity, maternal age, SES, pre-pregnancy BMI, parity, season of delivery, smoking during pregnancy, cord blood mtDNA content, and maternal MT-ND4L10550A>G. Trimester-specific estimates are given as odds ratio per 5 µg/m³ increment in PM2.5. Supplementary Table S5. Difference in cord blood MT-ND4L10550A>G heteroplasmy in association with week-specific prenatal exposure to PM2.5 (n = 386). Models were adjusted for gestational age, sex, ethnicity, maternal age, socioeconomic status, pre-pregnancy BMI, parity, season of delivery, smoking during pregnancy, cord blood mtDNA content, and maternal MT-ND4L10550A>G. Week-specific estimates are given as odds ratio per 5 µg/m³ increment in PM2.5. Supplementary Table S6. Difference in cord blood MT-ND4L10550A>G in association with week-specific prenatal exposure to PM2.5 without mothers who smoked during pregnancy (n = 345). Models were adjusted for gestational age, sex, ethnicity, maternal age, socioeconomic status, pre-pregnancy BMI, parity, season of delivery, cord blood mtDNA content, and maternal MT-ND4L10550A>G. Week-specific estimates are given as odds ratio per 5 µg/m³ increment in PM2.5. Supplementary Figure S1. Flowchart study population selection. The ENVIRONAGE birth cohort included 1993 mother-child pairs until March 2021. The study population (n = 400) was recruited between February 2010 and December 2015. The association between prenatal PM2.5 exposure and cord blood MT-ND4L10550A>G was analyzed for 386 mother-newborn pairs. The association between prenatal PM2.5 exposure or cord blood MT-ND4L10550A>G and childhood overweight was analyzed for 368 mother-newborn pairs. The mediation analysis was performed on 355 mother-child pairs. Supplementary Figure S2. Variation in cord blood MT-ND4L10550A>G heteroplasmy level (n = 400), ordered by study ID.

Reinhardorhynchus beatrizae Diez, Aguirre, Reygel & Artois sp. n. (Fig. 10) urn:lsid:zoobank.org:act: 7191A493-CCA1-421D-88D5-99AD3D7E5705 Material and distribution. Observations on live specimens, whole mounted afterwards. Two whole mounts from Las Sardinas (19°56’24”N; 76°46’41”W) (Type Locality), Guamá, Santiago de Cuba, Cuba (June 22, 2016), one of which is designated holotype (FMNH https://id.luomus.fi/ KV.649), the other one in HU (XIII.4.03), silty sand in rock pools protected from wave action, 0.3 m deep, salinity 33 ‰. Six whole mounts and three serially-sectioned specimens (in poor conditions) from Siboney (19°57’34”N; 75°42’07”W), Santiago de Cuba, Cuba (September 4, 2016; March 22 & June 5, 2017), intertidal (upper 10 cm of fine-grained sand) up to 0.5 m deep (fine-grained sand rich in organic matter), salinity 33–35 ‰ (HU XIII.4.04– XIII.4.13). Two whole mounts from Bueycabón (19°57’38”N; 76°57’28”W), Santiago de Cuba, Cuba (February 6 & 21, 2018), fine-grained sand rich in organic matter, 0.5 m deep, salinity 33 ‰ (HU XIII.4.14– XIII.4.15). Etymology. Species dedicated to Prof. Dr. Beatriz Martínez Daranas, researcher at the Marine Research Centre of Havana University, Cuba), specialist in taxonomy and ecology of seagrass and macroalgae. Diagnosis. Species of Reinhardorhynchus gen. n. with the copulatory bulb encompassing the prostate vesicle, an armed cirrus and two distal hooks. Cirrus armed with triangular, ±4-μm-long spines. Cirrus also includes a ±347- μm-long spiny belt. Proximally in the belt the spines are scale shaped and ±23 μm long. Proximal spines followed by a section bearing ±6-μm-long spines that runs distally and ends in the distal comb-shaped part, which is armed with ±32-μm-long spines. Larger hook ±101 μm long and ±59 μm wide at its base. Its base bears a ±45-μm-long and funnel-like hook. Smaller hook ±89 μm long and ±47 μm wide at its base. Description. Live specimens are 1.5–2 mm long, translucent, with two eyes (Fig. 10A: e). The syncytial and fully-ciliated epidermis is 7–8 μm thick and contains large vacuoles, some of which are filled with a dark granular secretion. Rhabdites occur all over the basal part of the epidermis and measure 2–3 μm. The proboscis (Fig. 10A: pr) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980), with a strong juncture sphincter, and does not differ in morphology from that of the other species of Reinhardorhynchus gen n. It is about 15% of the body length in live specimens. Only two pairs of integument retractors were observed: a ventral and a dorsal one. Two pairs of proboscis retractors were observed, but it is not clear whether more are present. The exact number of fixators and dilatators could not be determined. A sphincter around the proboscis pore was not observed. The pharynx is located at 40–50% (Fig. 10A: ph) and has a diameter of 15% of the body length in live specimens. Its overall morphology does not differ from that previously described for I. divae (see above). At least two types of glands open in the distal part of the pharynx lumen: one containing a coarse-grained secretion, the other one a fine-grained secretion. A pair of testes is located rostral to the pharynx. The seminal vesicles fuse with each other just before entering the copulatory bulb. The copulatory bulb is globular and 253–400 μm long (x̄ = 327 μm; n = 7). It is surrounded by an external, longitudinal and a very strong internal, circular muscle layer. The prostate glands open proximally into the copulatory bulb. The copulatory bulb encompasses the prostate vesicle, the cirrus and two distal hooks. The prostate vesicle (Fig. 10A: pv) opens proximally into the cirrus. The filiform prostate ducts contain a coarse-grained secretion. The cirrus is surrounded by an external longitudinal and a very strong internal circular muscle layer. The cirrus (Fig. 10A: ci) is armed with 3–5-μm-long triangular spines (Fig. 10B: cis) (x̄ = 4 μm; n = 20). Additionally, the cirrus also shows a 290–382-μm-long spiny belt (x̄ = 347 μm; n = 6) (Fig. 10C). Proximally, these scale-like spines are 9–34 μm long (x̄ = 23 μm; n = 15) (Fig. 10B–C: cps). This part is followed by a row of triangular and 4–8-μm-long (x̄ = 6 μm; n = 31) spines (Fig. 10C: cms). In the distal, comb-shaped part of the belt the spines are 23–48 μm long (x̄ = 32 μm; n = 31) (Fig. 10B–C: cds). The larger of the two distal hooks (Fig. 10B: h1, 10D; hooks Fig. 10A: h) is 86–121 μm long (x̄ = 101 μm; n = 7) and 49–72 μm wide at its base (x̄ = 59 μm; n = 8). The base carries a funnel-like structure of 35–53 μm long (x̄ = 45 μm; n = 7) (Fig. 10B & 10D: fh). The smaller hook (Fig. 10B: h 2, 10E) is 57–94 μm long (x̄ = 89 μm; n = 6) and 36–55 μm wide at its base (x̄ = 47 μm; n = 6). The vitellaria run from the posterior end of the pharynx to the caudal body end. The elongated ovaries are located rostral to the copulatory bulb. The oocytes are organised in one row, increasing in diameter from the most proximal to the most distal one. The oviducts open into the proximal end of the female duct. The female duct opens into the receptacle bursa (terminology of Karling 1981; followed by Reygel et al. 2011) through a strong sphincter. The muscular bursal stalk connects the caudally-located bursa with the female atrium. In a live specimen, an egg without shell was observed.

Reinhardorhynchus tahitiensis Jouk, Diez, Yurduseven, Reygel & Artois sp. n. (Fig. 15) urn:lsid:zoobank.org:act: EBAAD8FF-E519-48FE-8846-20693BD0C5A3 Material and distribution. Observations on live specimens. Three whole mounts, one of which designated holotype (FMNH https://id.luomus.fi/ KV.652), from Puna’auia (17°38’15”S; 149°36’47”W) (Type Locality), Pape’ete, Tahiti, Society Islands, French Polynesia (March 20, 2016), in front of the Méridien Hotel, sandy beach in front of coral heads with strong periodic currents, fine sand with detritus, about 0.5 m deep. Another whole mount from the same locality (March 1, 2016), in mixed sand with shell gravel, 1 m deep. Two serially-sectioned specimens from the type locality (October 3, 2017), 100 m from the seafront, sand patch in between coral heads, medium grained sand with some coral debris, 1.5 m deep. Three whole mounts from Avatoru, Rangiroa (14°58’48”S; 147°37’25”W), Tuamotu Archipelago, French Polynesia (March 7, 2016), second harbour, fine sand with detritus, 1.5 m deep. All the reference material deposited in HU (XIII.4.20– XIII.4.27). Etymology. Species named after Tahiti, where most of the specimens were found. Diagnosis. Species of Reinhardorhynchus gen. n. with the copulatory bulb encompassing the prostate vesicle, an armed cirrus and two distal hooks. Cirrus armed with four rows of triangular, ±3-μm-long spines. Rows ±93 μm, ±96 μm, ±41 μm, and ±49 μm long respectively. Longest two rows end in curved spines, which increase in length from the most proximal one (±6 μm long) to the most distal one (±27 μm long). Hooks ±24 μm long and ±18 μm wide at their base, ending bluntly with a very small, sharp tip directed sideways. Description. The specimens are 1.1–1.3 mm long (x̄ = 1.2 mm; n = 4), yellowish, with two eyes. Habitus and general organisation as in R. riae sp. n. The epidermis is 6 μm thick. Rhabdites, 7–9 μm long, more numerous in the posterior 2/3 of the specimen, deeply embedded within the epidermis. Some rhabdites stain pinkish, others yellowish. At the distal end, caudal glands are present (Fig. 15A: cgl). The proboscis (Fig. 15A: pr) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980). It represents 10% of the body length and has the same detailed morphology as that of R. riae sp. n.; see above. Only two kinds of glands open through the caudal wall of the proboscis: coarse-grained basophilic glands and fine-grained eosinophilic ones. The pharynx (Fig. 15A: ph) has a diameter of 15% of the body length, and is located at 40%. Its morphology does not differ from that in R. riae sp. n. There are two types of pharyngeal glands: coarse-grained basophilic and coarse-grained eosinophilic ones. In one specimen several diatoms were observe. Proximally, the pharynx opens into the oesophagus (Fig. 15A: oe). A pair of testes (Fig. 15A: t) is located rostrally from the pharynx. In the caudal body fourth, the vasa deferentia are swollen and form the seminal vesicles (Fig. 15A & 15D: sv), which are lined by longitudinal muscles and fuse with each other just before entering the copulatory bulb. The copulatory bulb (Fig. 15A & 15C: cb) is 208–245 μm long (x̄ = 228 μm; n = 7). It is lined by a coat of strong circular muscles, which are weakest distally. Proximally, prostate glands (Fig. 15A: pg) open into the copulatory bulb. The prostate vesicle (Fig. 15D: pv) contains two types of coarse-grained secretions: a basophilic and an eosinophilic one. Additionally, some fine-grained eosinophilic glands (Fig. 15D: gl) lie inside the muscular wall of the copulatory bulb. The prostate ducts open into the cirrus. Nuclei of both the basophilic and the eosinophilic glands are extracapsular and could only be observed in live specimens. The cirrus is armed with four rows of spines (Fig. 15A & 15D: spr). One row (Fig. 15B–C: spr1) is 88–104 μm long (x̄ = 93 μm; n = 3), the second one (Fig. 15B–C: spr2) 93–99 μm (x̄ = 96 μm; n = 3), the third one (Fig. 15C: spr3) 40–42 μm (x̄ = 41 μm; n = 3), and the last one (Fig. 15C: spr4) 49 μm (n = 3). The triangular spines that make up these rows are 2–4 μm long (x̄ = 3 μm; n = 30). The two largest rows distally end in large, curved, somewhat shark-tooth-shaped spines, increasing in length from the most proximal one (6 μm long) to the most distal one (27 μm long) (x̄ = 16 μm; n = 21). The two distal hooks (Fig. 15B–D: h) are similar to each other: broad-funnel shaped, 23–26 μm long (x̄ = 24 μm; n = 12) and 13–23 μm wide at their base (x̄ = 18 μm; n = 12), and end bluntly. Depending on the degree of the squeezing and the orientation of the hooks, some specimens reveal that these distal ends bear a small sharp tip directed sideways. The copulatory bulb opens into the male atrium (Fig. 15D: ma), which itself enters the common genital atrium (Fig. 15D: ca) through the latter’s rostro-dorsal wall. The ovaries (Fig. 15A: ov) are oval-shaped and located rostrally from the copulatory bulb. The vitellaria occur as a large mass throughout almost the complete body of the animal. In some specimens, however, they seemingly extend as one or two rows of large follicles from just caudally of the testes to alongside the copulatory organs (Fig. 15A: vi). The female duct is bipartite, with the proximal part (Fig. 15A & 15D: fd1) more or less globular and filled with living sperm, the distal part (Fig. 15D: fd2) more elongated. In one of the live specimens two separate spermpackages were observed within the proximal part of the female duct. A bundle of glands enters at the transition between the two compartments (Fig. 15A & 15D: fgl). The female duct is lined by an anucleated epithelium and a layer of strong circular muscles. Distally, the female duct opens into the female atrium (Fig. 15D: fa). The female atrium is surrounded by an inner weak circular and an outer longitudinal muscle layer. The epithelium of the female atrium could not be observed, probably because it is very low. The female duct enters the common atrium caudodorsally, but the exact point of entry could not be observed in the available material. The exact course of the oviducts could not be determined. The common genital atrium is lined by a low, anucleated epithelium. The uterus (Fig. 15D: ut) enters the common atrium caudally. It is lined by a nucleated epithelium and is surrounded by an inner layer of circular and an outer layer of longitudinal muscles. A sphincter separates the proximal third of the uterus from the distal part (Fig. 15D: sph). Distally from the sphincter, a bundle of fine-grained eosinophilic glands (Fig. 15D: ueg) enters the uterus. At its distal third, the uterus is surrounded by coarse-grained basophilic glands (Fig. 15D: ubg). The common gonopore (Fig. 15A & 15D: cg) is located at 90%. Caudally of the gonopore, a bursa (Fig15A: b) is present.

Reinhardorhynchus hexacornutus Jouk, Diez, Reygel & Artois sp. n. (Fig. 11) urn:lsid:zoobank.org:act: 45A01032-0A38-4976-9AF0-B2C6F277FC55 Material and distribution. Observations on live specimens, whole mounted afterwards. Five whole mounts, one of which is designated holotype (FMNH https://id.luomus.fi/ KV.650), the others in HU (XIII.4.16– XIII.4.19), collected in Puna’auia (17°36’42”S; 149°36’51”W) (Type Locality), Pape’ete, Tahiti, Society Islands, French Polynesia (March 18, 2016), sediment with ripple marks, 50 cm deep, fine black sand. Etymology. Species named after the presence of six hooks within the copulatory bulb. Diagnosis. Species of Reinhardorhynchus gen. n. with the copulatory bulb encompassing the ejaculatory duct, a papillary cirrus, and six hooks. Ejaculatory duct runs through the copulatory bulb and opens distally into the male atrium. Papillary cirrus ±84 μm long, armed with nail-shaped spines, ±2 μm long proximally and ±1.2 μm distally. Hooks funnel-shaped, curved, and ending in a sharp tip, each of different size, ranging from 11μm long and 5 μm wide to 54 µm long and 23 µm wide. Description. The specimens are 0.9–1.3 mm long (x̄ = 1.1 mm; n = 3), translucent, with a pair of eyes (Fig. 11A: e). The proboscis (Fig. 11A: pr) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980), with a strong juncture sphincter. The pharynx (Fig. 11A: ph) has a diameter of 10% of the body length in live specimens, and is located at 30%. Two testes (Fig. 11A: t) are positioned behind the pharynx. The vasa deferentia form the seminal vesicles (Fig. 11A–B: sv), which fuse to form a short seminal duct just before entering the copulatory bulb. The oval copulatory bulb is 125 μm long (n = 1) and encompasses the ejaculatory duct, a papillary cirrus, and six accessory hooks. The ejaculatory duct (Fig. 11B & 11J: ed) runs through the proximal part of the copulatory bulb and opens distally into the male atrium. The spiny part of the papillary cirrus (Fig. 11A–C & 11J–H: pc) is 73–91 μm long (x̄ = 84 μm; n = 4) and armed with nail-shaped spines. Proximally, these spines are 1.2–2.4 μm long (x̄ = 2 μm; n = 20) and dis- tally they decrease in size to ±1.2 μm (n = 15). Proximally, the papillary cirrus is enclosed in a papilla (Fig. 11A–C & 11J–K: pa), with a glandular organ opening into the cirrus. The accessory hooks (Fig. 11A: h, 11B & 11J–K: h1–h6, 11D–I) are funnel-shaped, curved, and ending in a sharp tip. They differ in size, ranging from 11 µm long and 5 µm wide at the base for the smallest one to 54 μm long and 23 µm wide for the largest one. The hooks are organised in two groups; one group is formed by hooks 1–4 (Fig. 11I, 11G, 11D & 11H, respectively) and the other group includes hooks 5–6 (Fig. 11F & 11E, respectively). The hooks 1–4 are located in a well-developed muscular sac. The vitellaria (Fig. 11A: vi) extend along both sides of the body from the level of the pharynx to the copulatory organs. A pair of ovaries (Fig. 11A: ov) is located at the midbody, rostral to the copulatory bulb. The oocytes are organised in a row. The oviducts open into the proximal end of the female duct. The female duct (Fig. 11A: fd) opens into the female atrium through a strong sphincter. The muscular bursal stalk (Fig. 11A: bs) connects the caudallylocated bursa (Fig. 11A: b) to the female atrium. The common gonopore (Fig. 11A: cg) opens at 80%.

Reinhardorhynchus anamariae Diez, Reygel & Artois sp. n. (Fig. 9, 12A–C) urn:lsid:zoobank.org:act: 68EBA829-BAD3-4F42-A46E-AC35A1F7F38D Material and distribution. Observations on live specimens, whole mounted afterwards. Four whole mounts, one of which is designated holotype (FMNH https://id.luomus.fi/ KV.648), the others in HU (XIII.3.50; XIII.4.01– XIII.4.02), collected in Bueycabón (19°57’38”N; 76°57’28”W) (Type Locality), Santiago de Cuba, Cuba (February 6, 2018), fine-grained sand with organic matter, 0.5 m deep, salinity 33 ‰. Etymology. Species dedicated to Prof. Dr. Ana María Suárez Alfonso, researcher at the Marine Research Centre of Havana University, Cuba, specialist in taxonomy and ecology of macroalgae. Awarded with the National Award of Marine Sciences of Cuba (2012). Diagnosis. Species of Reinhardorhynchus gen. n. without eyes. Copulatory bulb enclosing a spiny cirrus and two distal hooks. Cirrus armed with rows of spines ±1 μm long and a ±116-μm-long and inverted L-shaped belt of triangular spines. Proximally, the belt bears ±22-μm-long spines, diminishing in length from one end to the other (the proximal largest one is ±42 μm long and the smallest distal one is ±9 μm long). Distally in the belt, the central spines are ±15 μm long; the lateral ones are ±5 μm long. Larger hook ±51 μm long, distally ending in a sharp tip. Smaller hook ±45 μm long, with a blunt distal tip. Description. Specimens translucent, 0.9–1.4 mm long (x̄ = 1.2 mm; n = 4), with pinkish-coloured parenchymal glands, and without eyes. The proboscis (Fig. 9A: pr) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980), possessing a well-developed juncture sphincter; it is 15% of the body length in live specimens. The pharynx (Fig. 9A: ph) has a diameter of 15% of the body length in live specimens and is located at 50%. The testes (Fig. 9A: t) are rostral to the pharynx. Caudal to the pharynx, the vasa deferentia make up the seminal vesicles. The seminal vesicles fuse to form a short seminal duct just before entering the copulatory bulb. The seminal duct runs through the proximal part of the copulatory bulb and opens into the cirrus. The extracapsular prostate glands open proximally into the copulatory bulb. The oval copulatory bulb is 183–274 μm long (x̄ = 222 μm; n = 4). It encompasses the prostate vesicle (Fig. 9B: pv), the spiny cirrus, and two distal hooks. The cirrus (Fig. 9A–B & 12A: ci, 9C, 12B) is armed with rows of spines that are ±1 μm long (Fig. 9C & 12B: sp). Proximally, the rows of spines are oriented longitudinally, while distally they are transversal; these rows join in the middle third of the cirrus. The cirrus includes a belt of large, triangular, hollow spines (Fig. 9C & 12B: cir). This belt has the shape of an inverted L and is 96–129 μm long (x̄ = 116 μm; n = 4). The proximal part of the spiny belt is oriented trans- versally relative to the longitudinal axis of the cirrus, is 31–41 μm long (x̄ = 37 μm; n = 4) and includes the largest spines, which are hollow, increasing in diameter from the most proximal to the most distal one. The largest spine is 37–48 μm long (x̄ = 42 μm; n = 4), the rest of the spines are 9–34 μm long (x̄ = 22 μm; n = 22). The distal part is oriented longitudinally relative to the axis of the cirrus, measures 65–88 μm (x̄ = 79 μm; n = 4), and includes smaller spines than the proximal part. In this part, the spines are larger in the middle (9–18 μm long; x̄ = 15 μm; n = 20) than at the sides (2–8 μm long; x̄ = 5 μm; n = 25). Distally from the cirrus proper, two large hooks are present. The larger hook (Fig. 9A–B, 12A & 12C: h1, 9D) is 48–53 μm long (x̄ = 51 μm; n = 4), with an asymmetrical base of 29–36 μm in width (x̄ = 31 μm; n = 4). The hook ends in a sharp, distal tip. The smaller hook (Fig. 9E, 12A & 12C: h2) is 44–46 μm long (x̄ = 45 μm; n = 4), with a more or less triangular base, 31–35 μm wide (x̄ = 33 μm; n = 4), and the distal tip curved and rounded. The elongated ovaries are lying rostral to the copulatory bulb. The oocytes are organised in a row, increasing in diameter from the most proximal to the most distal one. The female duct (Fig. 12A: fd) contains sperm and opens into the globular, caudally-located bursa (Fig. 9A–B & 12A: b) through a strong sphincter (Fig. 12A: sph). The common gonopore opens at 90%. One live specimen carried two embryos (Fig. 9A: em) that are not surrounded by a thick egg-shell, suggesting the species is (ovo-)viviparous.

Itaipusa Marcus, 1949 Emended diagnosis of Itaipusa (after Marcus 1949 and Karling 1980). Representative of Koinocystididae with a proboscis with a juncture sphincter. Copulatory bulb of conjucta duplex-type. Male duct armed with spiny rows (the cirrus), except in I. biglandula Reygel et al. (2011), where it is unarmed. Without accessory sclerotised structures such as stylets or hooks. Type species. Itaipusa divae Marcus, 1949, by original designation. Other species. Itaipusa aberrans sp. n., I. acerosa (Brunet, 1972) Karling, 1978, I. biglandula, I. karlingi Mack-Fira, 1968, I. novacaledonica sp. n., I. sbui Willems & Artois in Willems et al., 2017, I. similis (Brunet, 1972) Karling, 1978, I. sophiae (Graff, 1905) Karling, 1978, and I. spinibursa Karling, 1978., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on page 456, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Marcus, E. (1949) Turbellaria Brasileiros (7). Boletins da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo Zoologia, 7 (14), 7 - 155. https: // doi. org / 10.11606 / issn. 2526 - 4877. bsffclzoologia. 1949.129106","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x","Reygel, P. C., Willems, W. R. & Artois, T. J. (2011) Koinocystididae and Gnathorhynchidae (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Galapagos, with the description of three new species. Zootaxa, 3096 (1), 27 - 40. https: // doi. org / 10.11646 / zootaxa. 3096.1.3","Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x","Karling, T. G. (1978) Anatomy and Systematics of Marine Turbellaria from Bermuda. Zoologica Scripta, 7, 25 - 248.","Mack-Fira, V. (1968) Turbellaries de la Mer Noire. Rapport de la Commission pour la Mer Mediterranee, 9 (2), 179 - 182.","Willems, W., Reygel, P., Van Steenkiste, N., Tessens, B. & Artois, T. (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","Graff, L. von (1905) Marine turbellarien Orottavas und der Kusten Europas. Zeitschrift fur wissenschaftliche Zoologie, 83, 68 - 148."]}

Reinhardorhynchus soror Diez, Reygel & Artois sp. n. (Fig. 14) urn:lsid:zoobank.org:act: 19AA34C8-D7BD-4299-93C0-31856253020B Material and distribution. Observations on live specimens, whole mounted afterwards. Three whole mounts from Tombolo West (08°48’05”N; 79°33’15”W) (Type Locality), Taboga Island, Panama (December 9, 2011), one of which designated holotype (USNM 1642508), the others in the USNM (1642509–1642510), from medium-coarse sand with ripple marks close to swash zone, small waves, salinity 28 ‰. Etymology. Species name refers to its similarities with R. beatrizae sp. n. Lat. soror: sister. Diagnosis. Species of Reinhardorhynchus gen. n. with a copulatory bulb encompassing a spiny cirrus and two distal hooks. Cirrus armed with triangular, ±5-μm-long spines. It also has a ±437-μm-long belt of spines, which shows three distinct regions: 1) a proximal part with curved and hook-shaped spines fused at their bases, the largest one ±57 μm long, the others measuring 6–40 μm, 2) a middle part with 3-μm-long spines, and 3) a distal, combshaped part armed with ±39-μm-long and triangular spines. The larger of the distal hooks curved, ±87 μm long and ±68 μm wide at its base; its base provided with a funnel-like, ±70-μm-long hook. Smaller hook ±59 μm long and ±59 μm wide at its base. Description. The specimens are 1.5–2.2 mm long (x̄ = 1.7 mm; n = 3), translucent, with two rounded eyes (Fig. 14A: e). The proboscis (Fig. 14A: pr) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980); it represents 15% of the body length in live specimens. The pharynx (Fig. 14A: ph) has a diameter of 15% of the body length in live specimens and is located at 40–50%. The testes (Fig. 14A: t) are located rostral to the pharynx. The seminal vesicles (Fig. 14A: sv) fuse just before entering the copulatory bulb. The male copulatory bulb is globular and 320–391 μm long (x̄ = 356 μm; n = 2). The prostate vesicle (Fig. 14A: pv) opens into the armed cirrus. The cirrus is of the same structure as that of R. beatrizae sp. n. The cirrus (Fig. 14A: ci) is armed with triangular, 4–5-μm-long spines (x̄ = 5 μm; n = 35) (Fig. 14F: cis). The cirrus also includes a 437-μm-long belt of spines (n = 1) (Fig. 14A: cir), which consists of three parts. The proximal part is provided with spines that are curved and hook shaped (Fig. 14B, 14F: cps, 14G), the largest one 55–60 μm long (x̄ = 57 μm; n = 3) and the other ones 6–40 μm long (x̄ = 18 μm; n = 3). This proximal part forms a continuous 62–72-μm-long row (x̄ = 66 μm; n = 3). The middle part forms a broad surface consisting of 3-μm-long spines (Fig. 14F: cms) and measuring 109 μm (n = 1). The distal part is 129–135 μm long (x̄ = 132 μm; n = 2) and consists of a continuous comb-shaped row of spines (Fig. 14C, 14F: cds). The spines in this part are 20–59 μm long (x̄ = 39 μm; n = 44) and increase in size from the most proximal one to the most distal one. There are two large distal hooks. The larger one (Fig. 14A & 14F: h 1, 14E) is 84–89 μm long (x̄ = 87 μm; n = 3) and 63–77 μm wide at its base (x̄ = 68 μm; n = 3), curved, and carries a funnel-like and 65–80 μm long (x̄ = 70 μm; n = 3) projection at its base (Fig. 14E–F: fh). This structure is straight, makes a ±90º angle with the main hook, and ends in a blunt tip. The hook proper is strongly curved and ends in a sharp tip. At its base, there is a small, more or less square and folded projection (Fig. 14E: fp). The smaller hook (Fig. 14A & 14F: h2, 14D) is 57–89 μm long (x̄ = 59 μm; n = 3) and 54–62 μm wide (x̄ = 59 μm; n = 3) at its base. The base of this hook is asymmetrical. The hook is slightly curved and ends in a sharp tip. Vitellaria were not observed. The ovaries are oval shaped (Fig. 14A: ov), located rostral to the copulatory bulb, with the oocytes organised in a row. The oviducts open into the female duct. The female duct opens into the receptacle bursa (terminology of Karling 1980) (Fig. 14A: rb) through a strong sphincter. In a live specimen one embryo (Fig. 14A: em), apparently not surrounded by a shell, was observed, suggesting the species is (ovo-)viviparous. The common gonopore (Fig. 14A: cg) is located ventrally, at 90%., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on pages 478-479, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x"]}

Galapagetula cubensis Diez, Reygel & Artois sp. n. (Fig. 17–19) urn:lsid:zoobank.org:act: 54453AD2-50DE-4451-AB22-86999485DCB8 Material and distribution. Observation on live specimens. One serially-sectioned specimen from Bueycabón (19°57’38”N; 76°57’28”W) (Type Locality), Santiago de Cuba, Cuba (November 18, 2017), designated holotype (FMNH https://id.luomus.fi/ KV.654), intertidal, scraping the upper 10 cm of the fine sand. One whole mount from Las Sardinas (19°56’24”N; 76°46’41”W), Santiago de Cuba, Cuba (June 22, 2016), fine, silty sand, 0.1 m deep, salinity 33 ‰, and two from El Masío (19°59’21”N; 76°16’35”W), Santiago de Cuba, Cuba (June 30, 2016), intertidal, upper 10 cm of the medium-coarse sand, salinity 33 ‰ (HU XIII.4.28– XIII.4.30). Etymology. The epithet refers to the occurrence of the new species in Cuba. Diagnosis of Galapagetula cubensis sp. n. Species of Galapagetula with mouth sphincter. The copulatory bulb encompasses a prostate vesicle, a seminal duct, and the ejaculatory duct, which distally ends in a small and unarmed penis papilla. Prostate glands enter the male duct separately from the seminal duct, forming a divisa-type copulatory organ. Stalk of the resorptive bursa with a strong sphincter. Female duct lacking a sphincter. Common gonopore caudal. Description. Live specimens about 1.5 mm long, translucent, with a pair of small eyes (Fig. 17A: e). Epidermis syncytial, 5–8 µm thick, fully ciliated. Cilia 5 µm long. The epidermis shows many vacuoles, some of which are empty, others are filled with a dark, granular secretion. The dark-stained rhabdites are 2–3 µm long. The proboscis (Fig. 17A & 19A: pr, 17B) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980), without a juncture sphincter. In live specimens it represents about 20% of the body length in live specimens. The exact number of fixators (Fig. 17B & 19A: pfix) and retractors (Fig. 17B: pret) muscles could not be determined. The cone retractors (Fig. 17B: cret) are well developed. A pair of ventral and a pair of dorsal integument retractors (Fig. 17B: iret) are present. Proboscis sheath surrounded by an external layer of longitudinal muscles. Several dilatators (Fig. 17B & 19A: dil) connect the proboscis sheath with the body wall. Most of these dilatators are very thin, except for some in the proximal half of the proboscis sheath. The proboscis pore (Fig. 17B & 19A: prp) is not surrounded by a sphincter. The proboscis sheath is lined by a nucleated and thick epithelium (Fig. 17B: pep). This epithelium is continuous with the epithelium covering the proboscis cone. Both epithelia contain oval to circular-shaped glands (reddish stained) (Fig. 17B & 19A: epg), albeit the sheath epithelium only in its most proximal part. Several proboscis glands lie just caudal to the proboscis: ventrally and dorsally there are coarse-grained basophilic glands (Fig. 17B: prg1), and in between them fine-grained eosinophilic (light-pink) (Fig. 17B: prg2) and medium-coarse-grained eosinophilic (dark-pink) (Fig. 17B: prg3) ones. The pharynx (Fig. 17A & 19A–D: ph, 17B) is located at 30%. It has a diameter of about 15% of the body length. The prepharyngeal cavity is lined by a nucleated epithelium and is surrounded by a layer of longitudinal muscles. Additional circular muscles occur externally from the longitudinal ones in the distal half of the cavity. The mouth (Fig. 17B: m) can be closed by a sphincter (Fig. 17B: sph). Two types of glands open into the pharynx lumen: coarse-grained eosinophilic ones distally (Fig. 17B: phg1), and more to the middle part of the pharynx, additional coarse-grained basophilic glands occur (Fig. 17B: phg2).An epithelium lining the pharynx lumen was not observed. The musculature of the pharynx consists of a layer of longitudinal muscles outside of the septum (Fig. 17B: lm1), which is continuous with the longitudinal muscles surrounding the prepharyngeal cavity, and a thick circular layer just inside (Fig. 17B: cm1). The longitudinal muscles at the inside of the septum, observed in several species of Itaipusa, are not observed in this species. The pharynx lumen is surrounded by an inner circular muscle layer (Fig. 17B: cm2) and an outer longitudinal one (Fig. 17B: lm2). Internal strong longitudinal muscles are present (Fig. 17B: ilm). Radial muscles (Fig. 17B: rm) run between the septum and the wall of the pharynx lumen. The oesophagus (Fig. 17B & 19A: oe) is surrounded by the digestive parenchyma (Fig. 17B: dip). This parenchyma shows several nuclei and dark-stained vacuoles. The gonads and atrial organs are located in the caudal fourth of the body. The pair of testes (Fig. 17A: t) is ventral. The vasa deferentia each form a seminal vesicle (Fig. 17A & 18: sv), and these fuse at the point where they enter the copulatory bulb (Fig. 17A & 19B–C: cb). At the same point, also the prostate glands (Fig. 17A, 18 & 19D: pg) open into the copulatory bulb. The copulatory bulb encompasses the free prostate vesicle (Fig. 18 & 19B–D: pv), the seminal duct (Fig. 18 & 19D: sd) and the male duct, which ends in an unarmed penis papilla (Fig. 17A, 18 & 19B: pp). The rest of the space of the copulatory bulb is filled with parenchymatic tissue, which appears syncytial (Fig. 18 & 19B: np). The seminal vesicles and the seminal duct are lined by a nucleated epithelium. The copulatory bulb is surrounded by a thick coat of circular muscles, which gradually becomes thinner distally and eventually disappears toward the penis papilla. The prostate vesicle opens proximally into the ejaculatory duct (Fig. 18: ed), next to the opening of the seminal duct (Fig. 18: sd), hence the copulatory organ is of the divisa type (see Karling 1956 for details). The prostate vesicle consists of a number of a coarse-grained eosinophilic glands. A connection with these prostate glands and the ones entering the copulatory bulb could not be observed, but as nuclei are only found in the extracapsular parts it is most likely that both are part of the same glandular system. The male duct is lined by a nucleated epithelium and surrounded by a layer of longitudinal muscles. Distally, the epithelium is thicker, and the male duct forms the penis papilla, which protrudes into the male atrium (Fig. 18: ma). Only the distal part of the male atrium seems to be surrounded by muscles, which are longitudinal; no muscles were seen around the proximal part. The vitellaria (Fig. 17A & 19A–D: vi) extend along both sides of the body from behind the pharynx up to the level of the copulatory bulb. The elongated ovaries (Fig. 17A: ov) are located on either side of the copulatory bulb. The oocytes are organised in a row, increasing in diameter from the most proximal to the most distal one. The oviducts (Fig. 18: od) open into the female duct, which distally is a bit swollen (Fig. 18 & 19C–D: fd). Both the oviducts and the female duct are lined by a nucleated epithelium. Distally, the female duct is surrounded by a thin lon- gitudinal muscle layer. It enters the female atrium through the latter’s rostro-ventral wall (Fig. 17A, 18 & 19B: fa). Two bursae open into the female atrium. A resorptive bursa (Fig. 18 & 19B–C: b1) opens rostrally into the female atrium and contains degraded material. It is lined by a nucleated epithelium. Its distal, tubiform part (bursal stalk) is surrounded by thin longitudinal muscles. A well-developed sphincter occurs at the place where this bursa opens into the female atrium (Fig. 18: sph1, 19B–D: sph). A second, muscular bursa [Fig. 18 & 19D: b2; accessory bursa in the terminology of Reygel et al. (2011)] opens dorsal-rostrally into the female atrium. It is lined by a nucleated epithelium and surrounded by a layer of longitudinal muscles. The female atrium is lined by a nucleated epithelium and surrounded by an internal layer of longitudinal muscles and an external layer of very strong circular muscles (Fig. 19C: cm). The uterus (Fig. 17A, 18 & 19B–C: ut) is lined by a nucleated epithelium and by a longitudinal muscle layer. Coarse-grained basophilic (Fig. 18 & 19B: ubg) and fine-grained eosinophilic (Fig. 18 & 19B: ueg) glands open into the distal part of the uterus. Proximally and distally from these glands sphincters are present (Fig. 18: sph2 & sph3). The common genital atrium (Fig. 18: ca) is lined by a nucleated epithelium and by a longitudinal muscle layer. It opens to the outside through the common gonopore, which is situated exactly terminally (Fig. 17A, 18 & 19D: cg). The gonopore is surrounded by a sphincter (Fig. 18: sph4)., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on pages 484-485, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x","Karling, T. G. (1956) Morphologisch-histologische Untersuchungen an den mannlichen Atrialorganen der Kalyptorhynchia (Turbellaria). Arkiv for Zoologi, Serie 2, 9 (7), 187 - 279.","Reygel, P. C., Willems, W. R. & Artois, T. J. (2011) Koinocystididae and Gnathorhynchidae (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Galapagos, with the description of three new species. Zootaxa, 3096 (1), 27 - 40. https: // doi. org / 10.11646 / zootaxa. 3096.1.3"]}

Reinhardorhynchus unicornis Diez, Aguirre, Reygel & Artois sp. n. (Fig. 16) urn:lsid:zoobank.org:act: B5662028-C218-43A0-9A93-7B2557629C76 Material and distribution. One specimen studied alive, whole mounted afterwards, designated holotype (FMNH https://id.luomus.fi/ KV.653), collected in Guardalavaca (21°07’32”N; 75°49’39”W) (Type Locality), Banes, Holguín, Cuba (February 28, 2017), fine-grained sand in a bed of Syringodium filiforme, 0.2 m deep, salinity 35 ‰. Etymology. The epithet refers to the copulatory organ, which is armed with a single accessory hook only. Diagnosis. Species of Reinhardorhynchus gen. n. with a copulatory bulb encompassing an ejaculatory cirrus, a papillary cirrus, and an accessory hook. Ejaculatory cirrus 73 μm long, armed with 5-μm-long, triangular spines. Papillary cirrus 119 μm long, armed with triangular, ±1-μm-long spines which become longer distally, up to ±11 μm. Curved hook 100 μm long and 40 μm wide at its asymmetrical base. Description. The specimen is 1.6 mm long, unpigmented, with a pair of eyes. The proboscis is about 20% of the body length in the live specimen. As far as could be seen on the live specimen, it shows the distinctive features of the typical koinocystidid proboscis (see Brunet 1972; Karling 1980), with a strong juncture sphincter. The pharynx (Fig. 16B: ph) has a diameter of 15% of the body length in live specimens, and is located at 40%. A pair of testes is located rostrally from the pharynx. The seminal vesicles (Fig. 16A–B & 16E: sv) fuse just before entering the copulatory bulb and form a short ejaculatory duct (Fig. 16A: ed). The extracapsular prostate glands (Fig. 16A: pg) open proximally into the copulatory bulb. The copulatory bulb (Fig. 16A) encompasses the prostate vesicle (Fig. 16A–B: pv), an ejaculatory cirrus, a papillary cirrus, and one distal hook. Proximally, a bundle of prostate glands opens into the copulatory bulb. The ejaculatory cirrus (Fig. 16A–B & 16E–F: ci) is 73 μm long and armed with 4–7-μm-long triangular spines (x̄ = 5 μm; n = 12). The papillary cirrus (Fig. 16A–B & 16E–F: pc, 16D) is proximally enclosed in a globular papilla (Fig. 16A: pa). It is 119 μm long and 24 μm wide, and armed with triangular and ±1-μm-long spines; some spines are larger distally (±11 μm long). The caudally-located hook (Fig. 16A–B & 16E: h, 16C) is 100 μm long and 40 μm wide at its asymmetrical base. The pair of ovoid ovaries is situated rostrally from the copulatory bulb, with the oocytes organised in a row. The vitellaria (Fig. 16B: vi) extend from beside the pharynx to the body end.

Simplexcystis Diez, Reygel & Artois gen. n. urn:lsid:zoobank.org:act: 27A436A5-2FD7-4059-A2D3-F75FF5104526, Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on page 488, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235

Galapagetula Reygel, Willems & Artois, 2011 Emended diagnosis of Galapagetula (after Reygel et al. 2011). Koinocystididae with proboscis of the typical koinocystidid construction without proboscis juncture sphincter. Testes lie at mid-body or more caudally. Copulatory organ pear shaped, distal part cylindrical, containing an unarmed or armed cirrus. Female duct widened proximally, functioning as a seminal receptacle, only surrounded with muscles in its tube-shaped distal part. Two bursae open separately into the female atrium, a muscular one (accessory bursa) and a resorptive one. Emended diagnosis of Galapagetula annikae (after Reygel et al. 2011). Species of Galapagetula without a mouth sphincter. Copulatory organ of the conjucta duplex-type, with a folded cirrus, armed with small spines. Female duct distally highly muscular with strong sphincter. Bursae without sphincters. Common gonopore at 85%., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on pages 482-483, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Reygel, P. C., Willems, W. R. & Artois, T. J. (2011) Koinocystididae and Gnathorhynchidae (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Galapagos, with the description of three new species. Zootaxa, 3096 (1), 27 - 40. https: // doi. org / 10.11646 / zootaxa. 3096.1.3"]}

Reinhardorhynchus riegeri (Karling, 1978) comb. n. (Fig. 4) Known distribution. Tuckers Town Cove (Type Locality) and Mullet Bay, Rock Hill, Bermuda (Karling 1978). New records and material. Observations on live specimens. Seven whole mounts (HU XIII.3.08– XIII.3.14) and five serially-sectioned specimens (HU XIII.3.15– XIII.3.19) from Guardalavaca (21°07’32”N; 75°49’39”W), Banes, Holguín, Cuba (February 28, 2017), sandy bottoms and fine-grained sand, in beds of Syringodium filiforme, intertidal up to 0.2 m deep, salinity 35 ‰. Description. Habitus and general organisation of the newly-collected specimens as described by Karling (1978). Specimens unpigmented, 1.4–2 mm long (x̄ = 1.8 mm; n = 6), with a pair eyes. The syncytial epidermis is 4 μm thick, fully ciliated. Cilia about 4 μm long. It includes two types of vacuoles: translucent empty ones and oth- ers filled with dark granules. Rhabdites present all over the epidermis, 1–2 μm long, some located at the epidermis’ surface, others deeply embedded within the epidermis. The proboscis represents about 10% of the body length in live specimens. It has the typical koinocystidid morphology (see Brunet 1972; Karling 1980), with a strong juncture sphincter and does not differ from that of other species of Reinhardorhynchus gen. n. (see the description of the proboscis of R. riae sp. n. below). Only two pairs of integument retractors were observed: a ventral and a dorsal one. The exact number of fixators, dilatators and proboscis retractors could not be determined. The proboscis pore is closed by a sphincter. The pharynx is located at 30%; its general morphology is as described for R. riae sp. n. (see below). However, a sphincter around the mouth was not observed. Three types of glands open in the distal part of the pharynx lumen: two eosinophilic ones (coarse-grained and medium-coarse grained, respectively) and a coarse-grained basophilic one. The two testes are located at both the sides of the pharynx. Each of them is connected to a seminal vesicle by a vas deferens. The seminal vesicles fuse proximally from the copulatory bulb, forming a short seminal duct. The copulatory bulb encompasses the prostate vesicle, two spiny cirri, and two distal hooks. The ejaculatory cirrus (terminology of Karling 1978) (Fig. 4A: ci, 4B) is 50–77 μm long (x̄ = 64 μm; n = 4). It is armed with numerous small spines of ± 7 μm long at one side and a group of larger spines 6–17 μm long (x̄ = 10 μm; n = 5) at the other. The papillary cirrus (terminology of Karling 1978) (Fig. 4A: pc, 4C) is 110–129 μm long (x̄ = 117 μm; n = 7). Its proximal half is provided with ±2-μm-long triangular spines (Fig. 4C: sp1), which in the distal half are 5–8 μm long (x̄ = 7 μm; n = 13) (Fig. 4C: sp2). The two larger, strongly sclerotised hooks, which are attached to the wall of the male duct, differ from each other in size. The larger hook (Fig. 4A: h1, 4D) is located next to the papillary cirrus and is 99–120 μm long (x̄ = 107 μm; n = 7). Its proximal base is extremely asymmetrical. The smaller one (Fig. 4A: h2; 4E) has a less pronounced asymmetrical base. It is positioned near the proximal end of the ejaculatory cirrus and measures 40–63 μm (x̄ = 56 μm; n = 5). Two elongated ovaries are situated rostral to the copulatory bulb. The oocytes are arranged in a row, increasing in diameter from the most proximal to the most distal one. The female duct receives the pair of oviducts proximally and opens into a distally located bursa through a strong sphincter. Embryos (4–5) without a surrounding shell were observed in some specimens, suggesting the species is (ovo-) viviparous.

Utelga pseudoheinckei Karling, 1980 (Fig. 20D–E) urn:lsid:zoobank.org:act: 27A436A5-2FD7-4059-A2D3-F75FF5104526 Syn. Utelga heinckei in Brunet (1965) and Mack-Fira (1974). Known distribution. Korsfjord (Tekslo Island, Hordaland Fylke), Kleppholmen Island, and Fugloy Island, Norway; California, USA (Karling 1980). Marseille area, France (Brunet 1965); Black Sea, Romania (Mack-Fira 1974). New records and material. Observations on live specimens. Four whole mounts (HU XIII.4.34– XIII.4.37) from Punta Negra (40°57’12”N, 8°13’43”E), Stintino, Sardinia, Italy (September 2018), on silty algae, 0.5 m deep, salinity 40 ‰. Remarks. The morphology of the specimens corresponds with the description of Karling (1980). The general habitus and internal organisation are very similar to those in U. heinckei. The elongated copulatory bulb is 92– 108 μm long (x̄ = 100 μm; n = 2) and 35 μm wide (n = 2). In a third specimen, not fully developed, the copulatory bulb is 49 μm long and 21 μm wide. The three hooks (Fig. 20D–E) at the distal end of the copulatory bulb are all of the same length, 5–8 μm long (x̄ = 7 μm; n = 6), with a broad base, curved and with a sharp tip., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on page 488, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x","Brunet, M. (1965) Turbellaries calyptorhynques de substrats meubles de la region de Marseille. Recueil des Travaux de la Station Marine d'Endoume, 39 (55), 128 - 218.","Mack-Fira, V. (1974) The turbellarian fauna of the Romanian littoral waters of the Black Sea and its annexes. In: Riser, N. W. & Morse, M. P. (Eds.), Biology of Turbellaria. McGraw-Hill, New York. pp. 248 - 290."]}

Utelga heinckei (Attems, 1897) Karling, 1954 (Fig. 20A–C) Known distribution. Western coast of USA, North Sea, Skagerrak, Irish Sea, Irish Atlantic coast (Karling 1980 and references therein). Skagerrak (Willems et al. 2007). Galapagos Islands (Reygel et al. 2011). British Columbia, Canada (Van Steenkiste & Leander 2018). New records and material. Observations on live specimens. One whole mount (HU XIII.4.31) from Las Sardinas (19°56’24”N; 76°46’41”W), Santiago de Cuba, Cuba (June 21, 2017), on Cladophoropsis macromeres covered by silt, 0.7 m deep, salinity 32 ‰. One whole mount (HU XIII.4.32) and one serially-sectioned specimen (HU XIII.4.33) from Mala (29°05’0.53”N; 13°26’59”W), Lanzarote, Canary Islands (October 8, 2011), medium coarse calcareous sand, from a very steep slope, 48 m deep, salinity 35 ‰. Remarks. The morphology of our specimens corresponds with the description of Karling (1980). Live specimens about 1 mm long, unpigmented, with a pair of eyes. The proboscis is about 10% of the body length. It shows the typical koinocystidid construction (see Brunet 1972; Karling 1980), without a juncture sphincter. The pharynx is located in the first body half. The testes lie caudal to the pharynx and ventral to the vitellaria. Two elongated ovaries are situated at the level of the copulatory bulb. Copulatory bulb surrounded by a sheath of strong circular muscles. At the distal end of the copulatory bulb three sclerotised hooks (Fig. 20A–C) occur, which differ from each other in size. The largest hook is 13–14 μm long (n = 2) and 5–6 μm wide proximally (n = 2). The smaller hooks are 4–6 μm long (x̄ = 5 μm; n = 4) and 2–4 μm wide proximally (x̄ = 3 μm; n = 4)., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on page 487, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Attems, C. G. (1897) Beitrag zur Kenntnis der rhabdocoelen Turbellarien Helgolands. Wissenschaftliche Meeresuntersuchungen der Kommission Abteilung Kiel, 2 (1), 219 - 232.","Karling, T. G. (1954) Einige marine Vertreter der Kalyptorhynchien-Familie Koinocystididae. Arkiv for Zoologi, 7, 165 - 183.","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x","Willems, W. R., Sandberg, M. I. & Jondelius, U. (2007) First report on Rhabdocoela (Rhabditophora) from deep parts of Skagerrak, with the description of four new species. Zootaxa, 1616 (1), 1 - 21. https: // doi. org / 10.11646 / zootaxa. 1616.1.1","Reygel, P. C., Willems, W. R. & Artois, T. J. (2011) Koinocystididae and Gnathorhynchidae (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Galapagos, with the description of three new species. Zootaxa, 3096 (1), 27 - 40. https: // doi. org / 10.11646 / zootaxa. 3096.1.3","Van Steenkiste, N. W. L. & Leander, B. S. (2018) Species diversity of eukalyptorhynch flatworms (Platyhelminthes, Rhabdocoela) from the coastal margin of British Columbia: Polycystididae, Koinocystididae and Gnathorhynchidae. Marine Biology Research, 14 (9 - 10), 899 - 923. https: // doi. org / 10.1080 / 17451000.2019.1575514","Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x"]}

Itaipusa aberrans Diez, Aguirre, Reygel & Artois sp. n. (Fig. 2) urn:lsid:zoobank.org:act: 171C2F91-B386-4BD4-B07A-CCDC27FAD1F1 Material and distribution. One specimen studied alive and whole mounted, designated holotype (FMNH https:// id.luomus.fi/ KV.646), collected in Siboney (19°57’34”N; 75°42’07”W) (Type Locality), Santiago de Cuba, Cuba (April 5, 2017), fine-grained sand rich in organic matter, 0.3 m deep, salinity 34 ‰. Etymology. Species named after the unique and aberrant structure of the cirrus. Diagnosis. Species of Itaipusa with an armed cirrus subdivided into two short, heavily folded plates, connected to each other by a thin duct lined by some small teeth. One plate is 32 μm long and bears a few spines 3–4 μm long. The second plate is spiral-shaped and armed with a few 1–9 μm long spines. Description. The specimen is 1.7 mm long, unpigmented, with two eyes (Fig. 2A: e). Proboscis (Fig. 2A: pr) of the typical koinocystidid construction (see Brunet 1972; Karling 1980); it is 10% of the body length in the live animal. The pharynx (Fig. 2A: ph) has a diameter of 15% of the body length in the live specimen, situated at 50%. A pair of testes is located antero-laterally from the pharynx. Paired elongated seminal vesicles fuse to form a short seminal duct just before entering into the copulatory bulb. The ovoid copulatory bulb (Fig. 2A: cb) encloses the prostate vesicle (typically encompassing numerous filiform ducts) and the armed cirrus (Fig. 2B–E). The cirrus is subdivided into two short, armed plates connected to each other by a narrow structure with some small folded sclerotised pieces (Fig. 2E: sfp). The first plate (Fig. 2B, 2D–E: pl1) is a heavily folded spiral and bears few 4–9- μm-long spines (x̄ = 7 μm; n = 5). The second plate (Fig. 2C, D–E: pl2) is 32 μm long, and also shows numerous folds and bears a few spines of 4–5 μm long (x̄ = 4 μm; n = 4). The spines of the structure connecting both plates are 1–2 μm long (x̄ = 1 μm; n = 8). The two elongated ovaries lie at midbody. The oocytes are organised in a row, increasing in diameter from the most proximal to the most distal one. The ovaries are flanked by the vitellaria (Fig. 2A: vi), which extend from behind the eyes to the caudal body end. The female duct receives the oviducts and opens into the female atrium through a strong sphincter. The caudally-located bursa is weakly muscular and contains sperm. The bursal stalk is very muscular and connects the bursa with the female atrium., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on pages 459-460, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x"]}

Simplexcystis asymmetrica Diez, Reygel & Artois gen. n. sp. n. (Fig. 21–23) urn:lsid:zoobank.org:act: BB2226F6-C526-47E4-8B49-F5CF45AB242E Material and distribution. Observations on one live specimen, serially sectioned afterwards, designated holotype (FMNH https://id.luomus.fi/ KV.655), collected in Playa Chica (28°55’05”N, 13°40’07”W) (Type Locality), Puerto del Carmen, Lanzarote, Canary Islands (October 10, 2011), fine sand accumulated at the end of the rocky reef, 18 m deep, salinity 35 ‰. Etymology. The genus name refers to the fact that the construction of the atrial organs in the new genus is relatively simple compared to that of other koinocystidids. The species name refers to the fact that the copulatory bulb is asymmetric due to the seminal duct entering laterally. Diagnosis of Simplexcystis gen. n. Representative of Koinocystididae with strong juncture sphincter in between proboscis bulb and cone. Male duct running eccentrically through the copulatory bulb, the latter also enclos- ing the prostate vesicle. Copulatory organ devoid of any hard structure. Without bursa. Epithelium of the female, the male, and part of the common atrium lined by a brush border. All these structures surrounded by a sheath of muscles in different orientations. Type species: S. asymmetrica sp. n. (by monotypy). Provisionally with the same diagnosis as the genus. Description. Live specimen about 1.5 mm long, translucent, with pinkish parenchymal glands and a pair of eyes (Fig. 21A: e). The brain (Fig. 21A: br) is located caudally from the proboscis. The syncytial and fully ciliated epidermis is 5–7 µm thick, with cilia 3–4 µm long. The epidermis shows many vacuoles some of which are empty, others filled with a dark, granular secretion. The epidermis shows many rhabdites (Fig. 21B–C, 22 & 23C–E: rh) all over the body, except for the part anterior to the proboscis. Rhabdites are also lacking around the mouth and gonopore. The rhabdites situated near the apical surface of the epithelium are globular, 1–2 µm in diameter, while those more to the basal part of the epithelium are more elongated (3–4 µm long). The proboscis (Fig. 21A: pr, 21B, 23A) is of the typical koinocystidid construction (see Brunet 1972; Karling 1980), with well-developed cone retractors (Fig. 21B & 23A: cret) and nuclei in the parenchyma of the proboscis bulb. In between the bulb and the cone there is a strong juncture sphincter (Fig. 21A–B & 23A: js). In the live specimen, the proboscis is about 15% of the body length. Several types of glands enter the proboscis through its caudal wall: dorsally coarse-grained basophilic ones (Fig. 21B: prg1), more centrally larger, fine-grained eosinophilic glands (stained pinkish) (Fig. 21B: prg2), and ventrally small fine-grained eosinophilic glands (stained yellowish) (Fig. 21B: prg3). There are three pairs of proboscis retractors (Fig. 21B: pret). The exact number of fixators (Fig. 21B & 23A: pfix) and dilatators (Fig. 21B: dil) could not be determined. There is one pair of ventral and one pair of dorsal integument retractors (Fig. 21B: iret). The proboscis sheath is lined by a high, nucleated epithelium and is surrounded by an external longitudinal muscle layer. The sheath epithelium is continuous with the epithelium of the proboscis cone, which is very low and devoid of nuclei. The most proximal part of the sheath epithelium contains some oval to circular-shaped eosinophilic gland cells (Fig. 21B & 23A: egl). The epithelium surrounding the cone is lined by a brush border (Fig. 23A: bb). The proboscis pore (Fig. 21B: prp) is surrounded by a sphincter (Fig. 21B: sph). The pharynx (Fig. 21A: ph, 21C, 23B) is located at 40%. In the live specimen, it has a diameter of 10% of the body length. The prepharyngeal cavity (Fig. 21C: ppc) is lined by a nucleated epithelium, and is surrounded by an internal circular and an outer longitudinal muscle layer. The mouth (Fig. 21C: m) can be closed by a sphincter (Fig. 21C: sph). Three types of glands open into the pharynx lumen: coarse-grained eosinophilic ones (stained reddish) opening most distally (Fig. 21C & 23B: phg1), and, opening more proximally coarse-grained eosinophilic ones (stained dark pinkish) (Fig. 21C & 23B: phg2) and coarse-grained basophilic ones (stained greenish) (Fig. 21C & 23B: phg3). The oesophagus (Fig. 21A, 21C & 23B: oe) is lined by a nucleated epithelium. A bundle of glands (Fig. 23B: oeg) opens into the oesophagus. It consists of coarse-grained basophilic glands (Fig. 21C: oeg1), fine-grained basophilic ones (Fig. 21C: oeg2), and fine-grained eosinophilic ones (Fig. 21C: oeg3). The pharynx lumen is surrounded by a low, nucleated epithelium. The musculature of the pharynx consists of a layer of longitudinal muscles outside of the septum (Fig. 21C: lm), which is continuous with the longitudinal muscles surrounding the prepharyngeal cavity, and a circular one just inside of the septum (Fig. 21C: cm1). The distal opening of the pharynx is lined by a thick layer of longitudinal muscles, which in sagittal section, gives the impression of forming a lip-like structure (Fig. 21C & 23B: slm). The pharynx lumen is surrounded by a circular muscle layer (Fig. 21C: cm2). Radial muscles run (Fig. 21C & 23B: rm) between the wall of the pharynx lumen and the outer septum. The two elongated testes (Fig. 21A: t) are located rostrally from the pharynx. They seem to be divided into three follicles that are closely packed together. However, this could also be an optic effect caused by the testes being heavily folded. The vasa deferentia run towards the caudal body end, and distally form the elongated seminal vesicles (Fig. 21A & 22: sv). The seminal vesicles are lined by a low, nucleated epithelium, and are surrounded by longitudinal muscles. The copulatory bulb is oviform, and lies in the caudal body third (Fig. 21A & 23C: cb). It is surrounded by a longitudinal muscle layer. Distally from the seminal vesicles, the vasa deferentia enter the ejaculatory duct separately (Fig. 21A, 22 & 23C–E: ed). The ejaculatory duct is elongated, with its distal half situated eccentrically within the copulatory bulb (Fig. 21A & 23C: cb). Distally the seminal duct opens into the male atrium, surrounded by the prostate vesicle (Fig. 22 & 23C–E: pv), which also opens in the male atrium. The seminal duct is lined by a low nucleated epithelium, and is surrounded by longitudinal muscles. The prostate glands (Fig. 22: pg) are extracapsular, without clearly separated gland necks in the prostate vesicle. The latter contains a coarsegrained eosinophilic secretion in its proximal half and a fine-grained one in its distal half. The male atrium (Fig. 22 & 23D–F: ma) is divided into a short, broad proximal part, and a tubiform distal part, which ends in the common genital atrium (Fig. 22 & 23C: ca). The male atrium, the female atrium, and the common genital atrium are lined by a nucleated epithelium and are surrounded by longitudinal muscles. Outside of this longitudinal muscle layer, a thick layer of muscles with different orientations (probably circular and oblique ones) and connective tissue occurs (Fig. 22 & 23C–F: tl). At its apical side the epithelium is lined by a brush border (Fig. 22 & 23D–F: bb), which is lacking in the most distal part of the common genital atrium. In the live specimen, we only observed a single, poorly differentiated ovary (Fig. 21A & 22: ov), located at the level of the seminal vesicles. In the serially-sectioned specimen, we observed two weakly developed oviducts, suggesting that the female system in full maturity has two ovaries. The very long oviducts (Fig. 22: od) are lined by a nucleated epithelium; muscles were not observed. They open proximally into the female duct (Fig. 21A, 22 & 23D–F: fd). The female duct is lined by a nucleated epithelium and contains sperm. It opens into the female atrium (Fig. 22, 23D & 23F: fa) through a strong sphincter (Fig. 21A & 23E–F: sph, 22: sph1). The female atrium enters the common genital atrium dorsally. There is no bursa. The uterus (Fig. 21A, 22, 23C: ut) is lined by a nucleated epithelium and surrounded by longitudinal muscles. Coarse-grained eosinophilic uterine glands (Fig. 22: ueg) open into the uterus somewhat proximally from the entry point into the common genital atrium. Just distally from the entry point of the uterus, some fine-grained eosinophilic atrial glands (Fig. 22: ag) enter the common genital atrium. The common gonopore lies ventrally, at about 95% (Fig. 21A, 22 & 23C: cg), and can be closed by a sphincter (Fig. 22: sph2, 23C: sph).

Itaipusa karlingi Mack-Fira, 1968 (Fig. 1D–E) Known distribution. Several localities in Romania, Black Sea (Mack-Fira 1968, 1974). Toulon and Le Brusc, France (Brunet 1972). Lussin Grande, Croatia (Karling 1980). New records and material. Observations on live specimens. Two whole mounts (HU XIII.2.49– XIII.2.50) from Punta Negra (40°57’12”N, 08°13’43”E), Stintino, Sardinia, Italy (September 9, 2018), on silty algae, 0.5 m deep, salinity 40 ‰. Three whole mounts (HU XIII.3.01– XIII.3.04) and two serially-sectioned specimens (HU XIII.3.05– XIII.3.06) from a sheltered beach at the south of Orzola (29°13’23”N; 13°27’05”W), Lanzarote, Canary Islands (October 6, 2011), medium-coarse sand with holes from burrowing animals, taken at low tide, just below the water line, one specimen collected at the same previous mentioned conditions but the sand was covered by a green organic material, salinity 35 ‰. Remarks. Habitus and general organisation of the newly-collected specimens as described by Mack-Fira (1968) and Karling (1980). Sardinian specimens are 0.8–0.9 mm long and the specimens from Lanzarote are 1–1.4 mm long (x̄ = 1.1 mm; n = 3). The syncytial epidermis is 3–4 μm thick, fully ciliated. Rhabdites distributed over the entire surface, 1–2 μm long, most of them stain pinkish in sections, few are stained black. Cilia 4 μm long. The proboscis is 15% of the body length in live animals. It has the typical koinocystidid morphology (see Brunet 1972; Karling 1980), with a strong juncture sphincter. Only two pairs of integument retractors were observed: a ventral and a dorsal one. The pharynx morphology does not deviate from that of Itaipusa divae (see above). The pharynx is located at 40% and its diameter represents 15% of the body length in live animals. A sphincter surrounds the mouth. Four types of glands open close to each other in the distal part of the pharynx lumen: three types of eosinophilic glands with a coarse-grained secretion (staining dark pink, pinkish, and brownish, respectively) and one type of basophilic glands with a coarse-grained secretion (staining dark purple). The oviform copulatory bulb (Fig. 1D–E: cb) is 174–184 μm long (x̄ = 179 μm; n = 2) in the specimens from Sardinia and 188–213 μm long (x̄ = 200 μm; n = 3) in the specimens from Lanzarote. The copulatory bulb encloses the prostate vesicle, the armed cirrus, and more distally a sclerotised penis papilla. Two types of filiform gland ducts containing a coarse-grained secretion (eosinophilic and basophilic) occur in the prostate vesicle. The cirrus bears two spiny belts, armed with scale-like spines provided with 1-μm-long apical denticles. The proximal spiny belt (Fig. 1D–E: cir1) in the Sardinian specimens is 106–127 μm long (x̄ = 117 μm; n = 2), with the lateral spines 2– 5 μm long (x̄ = 3 μm; n = 12), those more in the middle of the row 7–9 μm long (x̄ = 8 μm; n = 20). In the specimens from Lanzarote the proximal spiny belt is 138–153 μm long (x̄ = 146 μm; n = 2), with the lateral spines 3–5 μm long (x̄ = 4 μm; n = 12) and the central ones 8–10 μm long (x̄ = 9 μm; n = 10). The distal spiny belt (Fig. 1D: cir2) is 41–58 μm long (x̄ = 50 μm; n = 2) in the specimens from Sardinia and does not show marked differences in the length of the spines, each measuring 3–5 μm (x̄ = 4 μm; n = 20). In the specimens from Lanzarote the distal belt is 59–75 μm long (x̄ = 66 μm; n = 2), with spines 4–5 μm long (x̄ = 5 μm; n = 10). The penis papilla (Fig. 1D–E: pp) is 34–43 μm long (x̄ = 39 μm; n = 2) and 31–34 μm wide (x̄ = 33 μm; n = 2) in the specimens from Sardinia and 41–48 μm long (x̄ = 45 μm; n = 3) and 25–48 μm wide (x̄ = 39 μm; n = 3) in the specimens from Lanzarote. The uterus enters the common atrium rostro-ventrally. There are no sphincters surrounding the distal part of the uterus. It is lined by a nucleated epithelium and surrounded by longitudinal muscles. Three types of glands open into the uterus: one producing a very coarse-grained eosinophilic secretion, and two producing an eosinophilic secretion (fine-grained and coarse-grained, respectively). The bursal stalk shows the typical sclerotised membranes described for the species (see Mack-Fira 1974; Karling 1980). The female duct opens into the bursa through the typical strong sphincter., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on pages 457-459, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Mack-Fira, V. (1968) Turbellaries de la Mer Noire. Rapport de la Commission pour la Mer Mediterranee, 9 (2), 179 - 182.","Mack-Fira, V. (1974) The turbellarian fauna of the Romanian littoral waters of the Black Sea and its annexes. In: Riser, N. W. & Morse, M. P. (Eds.), Biology of Turbellaria. McGraw-Hill, New York. pp. 248 - 290.","Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x","Marcus, E. (1949) Turbellaria Brasileiros (7). Boletins da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo Zoologia, 7 (14), 7 - 155. https: // doi. org / 10.11606 / issn. 2526 - 4877. bsffclzoologia. 1949.129106"]}

Reinhardorhynchus riae Diez, Reygel & Artois sp. n. (Fig. 7–8) urn:lsid:zoobank.org:act: 65D70F61-74DB-458B-B5EA-18AB0F972270 Material and distribution. Observations on live specimens. Three whole mounts, one designated holotype (FMNH https://id.luomus.fi/ KV.651), the others reference material (HU XIII.3.33– XIII.3.34), and one serially-sectioned specimen (HU XIII.3.35) collected in Mala (Lanzarote, Canary Islands) (29°05’01”N; 13°26’59”W), in front of “Cuevita de Mala” (October 10, 2011), sand patch under loose macroalgae, coarse shell gravel, very clean, 12 m deep (Type Locality). One whole mount from the same locality (HU XIII.3.36) (October 8, 2011), medium-fine, calcareous sand from a large parch among rocks, poorly-oxygenated redox layer just below surface, 20 m deep. Four whole mounts and seven serially-sectioned specimens (HU XIII.3.37– XIII.3.47) collected in a sheltered beach, a bit south of Orzola (Lanzarote, Canary Islands) (29°13’23”N; 13°27’05”W) (October 6, 2011), medium-coarse sand, with holes from burrowing animals, taken at low tide, just below the water line. One whole mount (HU XIII.3.48) collected at the same locality (October 7, 2011), sample taken 0.4–0.5 m deep, coarse sand with lava rocks scattered around. Salinity 35 ‰ in all the localities. One whole mount (HU XIII.3.49) from Punta Negra (40°57’12”N, 08°13’43”E), Stintino, Sardinia, Italia (September 2018), on silty algae, 0.5 m deep, salinity 40 ‰. Etymology. Species dedicated to Ria Vanderspikken (Hasselt University), in acknowledgement of all her help in organising the sampling campaigns, archiving of literature and taking care of the HU specimen collection. Diagnosis. Species of Reinhardorhynchus gen. n. with a copulatory organ armed with two transverse spiny belts, a penis papilla, and two distal hooks. Prostate vesicle enclosed in a muscular bulb. This bulb ends in a pseudocuticular plate and is armed with two spiny rows being ±72 μm and ±55 μm long, respectively. Spines ±3 μm long at the sides and ±9 μm long in the middle of the rows. Penis papilla covered by a pseudocuticula, which carries the distal hooks. Hooks flattened, with a broad and rounded distal end, ±14 μm long and ±32 μm wide at their base. Female duct bipartite: proximal compartment lined by a nucleated epithelium and without muscles, distal compartment surrounded by a thick layer of circular muscles. Description. The specimens are 1.8–3 mm long (x̄ = 2.2 mm; n = 8), translucent, with a pair of eyes (Fig. 7A: e). The coloration of the specimens is due to pinkish glands within the parenchyma. The syncytial epidermis is 7–8 µm thick and completely ciliated; cilia ± 4 µm long. The epidermis contains many vacuoles, which are either empty or filled with a dark secretion (coarse- or fine-grained). The 1–2 µm-long rhabdites are located near the apical surface of the epidermis. Caudally in the body some eosinophilic glands occur (Fig. 7A & 8C: cgl). The proboscis (Fig. 7A: pr, 7B, 8A) is ±15% of the body length and is of the characteristic koinocystidid construction (see Brunet 1972; Karling 1980), displaying a strong juncture sphincter (7A–B: js). The proboscis sheath is surrounded by a nucleated epithelium (Fig. 7B: ne), which is continuous with the epithelium surrounding the proboscis cone. Both epithelia contain oval to circular-shaped glands (reddish stained) (Fig. 7B & 8A: egl). The epithelium surrounding the cone is lined by a brush border (Fig. 8A: bb). Three kinds of glands open through the caudal wall of the proboscis: coarse-grained basophilic ones (dark stained) (Fig. 7B: prg1), coarse-grained eosinophilic ones (pinkish stained) (Fig. 7B: prg2), and fine-grained eosinophilic ones (brownish stained) (Fig. 7B:prg3). The proboscis sheath is surrounded by a layer of circular muscles and a longitudinal one just underneath it. The pro- boscis pore (Fig. 7B & 8A: prp) is surrounded by a sphincter (Fig. 7B: sph). The cone retractors are well developed (Fig. 7B & 8A: cret). The exact number of proboscis fixators (Fig. 7B: pfix) and dilatators (Fig. 7B: dil) could not be determined. Two pairs of proboscis retractors (Fig. 7B: pret) could be distinguished, however it is not clear if there are more. Two pairs of integument retractors were observed: a ventral and a dorsal one (Fig. 7B: iret). The pharynx (Fig. 7A: ph, 7C) has a diameter of 15% of the body length in the live specimens, situated at 40%. The prepharyngeal cavity (Fig. 7C: ppc) is lined by a nucleated epithelium and surrounded by an external layer of longitudinal muscles. The mouth (Fig. 7C: m) is surrounded by a sphincter (Fig. 7C: sph). Four types of glands containing a coarse-grained secretion open into the pharynx lumen: dark brown (Fig. 7C: phg1) and pinkish (Fig. 7C: phg2) eosinophilic glands most distally, and brownish eosinophilic (Fig. 7C: phg3) and basophilic glands (Fig. 7C: phg4) more proximally. Coarse-grained basophilic glands (Minot’s glands) (Fig. 7C: oeg) open into the oesophagus (Fig. 7C: oe). The musculature of the pharynx consists of a longitudinal muscle layer outside of the septum (Fig. 7C: lm1) and a circular layer just inside of it (Fig. 7C: cm1). These circular muscles are markedly thicker near the proximal and distal tips of the pharynx. The distal opening of the pharynx is lined by a thick layer of longitudinal muscles, which in sagittal section gives the impression of forming a lip-like structure (Fig. 7C: slm). The pharynx lumen is surrounded by an inner circular (Fig. 7C: cm2) and outer longitudinal muscle layer (Fig. 7C: lm2). Radial muscles (Fig. 7C: rm) stretch between the internal and the external walls; the most proximal of these are weaker than the others. Two testes (Fig. 7A: t) occur latero-rostrally from the pharynx. Caudally from the pharynx, the vasa deferentia form a pair of seminal vesicles (Fig. 7A & 8C: sv). The seminal vesicles are lined by a low, nucleated epithelium and surrounded by an external, longitudinal muscle layer. The seminal vesicles fuse to form a seminal duct just before opening into the copulatory bulb (Fig. 7D: cb), which is located in the caudal body half and represents 15% of the body length in the live specimens. It encompasses the prostate vesicle (Fig. 7A & 8C: pv), the cirrus (Fig. 7A & 7D–E: ci), and two accessory hooks (Fig. 7A, 7D–E & 8C: h). The copulatory bulb ends in a penis papilla (8B–C: pp) and is surrounded by a thick sheath of longitudinal muscles (Fig. 8B–C: lm1). Distally, this muscular sheath is not connected to the penis papilla. A second, internal muscular sheath connects to the proximal part of the prostate vesicle and ends in the penis papilla. This sheath consists of a longitudinal muscle layer (Fig. 8B–C: lm2) and an oblique one just beneath it (Fig. 8B–C: om1). The most distal part of the copulatory bulb is lined by a thin, nucleated epithelium (Fig. 8C: ne), which becomes much thicker and is covered by a sclerotised layer, as a whole forming the penis papilla. The two distal hooks are connected to the distal end of the penis papilla. The extracapsular prostate glands (Fig. 7A & 8C: pg) open proximally into the copulatory bulb. The prostate vesicle forms a long-drawn muscular bulb. Proximally, it is surrounded by strong oblique muscles (Fig. 8B–C: om2), while over the rest of its length the prostate vesicle is surrounded by an external longitudinal (Fig. 8B–C: lm3) and internal oblique muscle layer (Fig. 8C: om3). The ejaculatory duct (Fig. 8B–C: ed) enters the prostate vesicle through the latter’s proximal end and runs axially through it. The duct is lined by a thin nucleated epithelium and surrounded by longitudinal muscles. There are four types of prostate glands: a coarse-grained basophilic one (stained dark purple) (Fig. 8B: pg1), two coarse-grained eosinophilic ones [stained greenish (Fig. 8B: pg2) and reddish (Fig. 8B: pg3), respectively], and an eosinophilic, fine-grained one (stained pinkish) (Fig. 8B: pg4). Distally, these prostate glands open around the distal opening of the ejaculatory duct. The distal tip of the prostate vesicle is covered by a sclerotised layer and armed with teeth, constituting the two spiny rows observed in the live specimens and the whole mounts. The spiny rows (Fig. 7D–E & 8C: ci) are oriented transversally relative to the copulatory bulb. The larger row is 66–83 μm long (x̄ = 72 μm; n = 7), the smaller one 46–65 μm (x̄ = 55 μm; n = 7). The triangular spines are small- est at the sides of both rows: 2–4 μm long (x̄ = 3 μm; n = 20), compared to 7–12 μm long (x̄ = 9 μm; n = 35) in the middle. The distal hooks (Fig. 7A, 7D–E & 8C: h) are similar in length and shape: flattened, distally broad and rounded, 11–20 μm long (x̄ = 14 μm; n = 10) and 27–37 μm wide at their base (x̄ = 32 μm; n = 10). The male atrium (Fig. 8C: ma) is lined by a low, nucleated epithelium and surrounded by longitudinal muscles. Proximally from the aperture of the ejaculatory duct, the male atrium shows a small, lightly-sclerotised papilla (Fig. 8C: pa). The male atrium opens into the common general atrium (Fig. 8C: ca) through the latter’s rostral wall. The vitellaria (Fig. 7A & 8C: vi) extend along both sides of the body from the level of the testes to the copulatory bulb. The ovaries (Fig. 7A & 8C: ov) are located antero-laterally from the copulatory bulb. The oocytes are organised in a row, increasing in diameter from the most proximal to the most distal one. The most distal oocytes display a number of unidentified black spots (Fig. 8C: os). The oviducts (Fig. 8C: od) are short and not surrounded by muscles. The female duct is bipartite. The proximal part (Fig. 8C: fd1) is surrounded by a nucleated epithelium, lacks muscles, and narrows towards the second, more distal part (Fig. 8C: fd2). The distal part is lined by a membranous, anucleated epithelium and surrounded by thick, circular muscles. The proximal part receives the broad common vitelloduct and the oviducts and is filled with vitelline material. The distal part contains sperm, hence functioning as seminal receptacle and connects to the female atrium through a strong sphincter (Fig. 8C: sph1). The female atrium (Fig. 8C: fa) also receives the bursal stalk (Fig. 8C: bs), which enters just dorsal to the female duct. The bursa (Fig. 8C: b) is surrounded by an internal longitudinal and external circular muscle layer which continue around the bursal stalk and further around the female atrium. It is lined by a nucleated epithelium, which disappears around the bursal stalk. At the transition between bursa and bursal stalk, a sphincter occurs (Fig. 8C: sph2). The bursa contains disintegrating sperm and different kinds of glandular material in degradation. The female atrium also contains sperm and enters the common genital atrium just dorsal to the opening of the male atrium. The uterus (Fig. 8C: ut) enters the common genital atrium through the latter’s rostral wall, ventral to all other systems. The uterus is lined by a nuclear epithelium and is surrounded by a longitudinal muscle layer. Medium-grained eosinophilic uterine glands open into the uterus just proximal to the opening of the female duct (Fig. 8C: ueg). The uterus does not show any sphincters. The common genital atrium is surrounded by longitudinal muscles. An epithelium was not observed and is probably membranous. The common genital atrium opens ventrally and subcaudally through the common gonopore (Fig. 7A & 8C: cg), which is at 95%. This gonopore is surrounded by a sphincter (Fig. 8C: sph3). One live specimen carried two embryos (Fig. 8B: em) not surrounded by a thick egg-shell, suggesting the species is (ovo-)viviparous., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on pages 466-469, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x"]}

Reinhardorhynchus pacificus Diez, Reygel & Artois sp. n. (Fig. 12D–F, 13) urn:lsid:zoobank.org:act: C5DDBEEF-C3CA-456D-9330-440CFA8B10E4 Material and distribution. Observations on live specimens, whole mounted afterwards. Two whole mounts collected in Playa Venao (08°53’06”N; 79°36’07”W) (Type Locality), Vera Cruz, Panama (December 2, 2011), one of which is designated holotype (USNM 1642506), the other one in the USNM (1642507), coarse-grained sand with fine silt, salinity 30 ‰. Etymology. The two specimens were found at the Pacific coast of Panama. Diagnosis. Species of Reinhardorhynchus gen. n. with a copulatory bulb encompassing a papillary cirrus, an ejaculatory cirrus, an accessory cirrus, and two hooks. Ejaculatory cirrus ±171 μm long, armed with scale-like spines along its entire length that are ±5 μm wide proximally and ±2 μm wide distally. Few larger triangular spines occur proximally (±10 μm long) and distally (±4 μm long). Accessory cirrus ±92 μm long, proximally armed with ±6-μm-long triangular spines and distally with 3-μm-long triangular spines and ±3-μm-wide and scale-like spines. Distal rims of these spines serrated, bearing ±1-μm-long spinules. Papillary cirrus ±62 μm long, proximally cov- ered by fine spines of ±2 μm long and distally with ±6-μm-long triangular spines. The hooks are ±83 μm long and ±81 μm long, respectively. Description. The specimens are 1.7 mm long, colourless, with two eyes (Fig. 13A: e). The brain (Fig. 13A: br) is located caudally from the proboscis. The proboscis (Fig. 13A: pr) has the typical koinocystidid morphology (see Brunet 1972; Karling 1980) and shows a strong junction sphincter; it represents 10% of the body length in live specimens. The pharynx (Fig. 13A: ph) has a diameter of ±15% of the body length in live specimens, and is located at 30–40%. Caudally in the body some eosinophilic glands occur (Fig. 13A: cgl). The two testes (Fig. 13A: t) are located rostrally from the pharynx. The seminal vesicles (Fig. 12D & 13A: sv) fuse proximally from the copulatory bulb, forming a short seminal duct. The copulatory bulb is 363–403 μm long (x̄ = 383 μm; n = 2). It encompasses the prostate vesicle (Fig. 13A: pv), the ejaculatory cirrus (terminology of Karling 1978), an accessory cirrus, a papillary cirrus (terminology of Karling 1978), and two distal hooks. The ejaculatory cirrus (Fig. 12D–E & 13A: ci, 13B) is 162–180 μm long (x̄ = 171 μm; n = 2) and armed with scalelike spines over its entire length. These spines are 5–6 μm wide (x̄ = 5 μm; n = 20) proximally and 2–3 μm wide (x̄ = 2 μm; n = 20) distally. Additionally, a number of larger triangular spines occur proximally, measuring 6–13 μm (x̄ = 10 μm; n = 10), and a group of small triangular spines is present distally, measuring 3–4 μm (x̄ = 4 μm; n = 13). The accessory cirrus (Fig. 12D–E & 13A: ac, 13C) is 89–95 μm long (x̄ = 92 μm; n = 2), proximally armed with triangular spines 4–10 μm long (x̄ = 6 μm; n = 24) and distally with triangular spines 2–4 μm long (x̄ = 3 μm; n = 9) and scale-like spines 2–5 μm wide (x̄ = 3 μm; n = 15). The distal rim of the scale-like spines of the accessory cirrus is serrated, with 1-μm-long spinules. The spiny part of the papillary cirrus (Fig. 12D–E, 13A & 13D: pc) is 55–69 μm long (x̄ = 62 μm; n = 2) and proximally enclosed in a papilla (Fig. 13D: pa). Papilla and cirrus are separated from each other by a sphincter (Fig. 13D: sph). The papillary cirrus is proximally armed with fine spines, ±2 μm long, and distally with triangular spines, 4–8 μm long (x̄ = 6 μm; n = 6). The two funnel-shaped distal hooks are nearly equal in size. One hook (Fig. 12D–E & 13A: h 1, 13E) is 79–86 μm long (x̄ = 83 μm; n = 2) and 40–43 μm wide at its base (x̄ = 42 μm; n = 2). The other hook (Fig. 12D–E & 13A: h2, 13F) is 79–83 μm long (x̄ = 81 μm; n = 2) and 59–65 μm wide at its base (x̄ = 62 μm; n = 2). Vitellaria were not observed. The oval-shaped ovaries (Fig. 13A: ov) are located rostrally from the copulatory bulb. The oocytes are organised in a row. The oviducts (Fig. 13A: od) open into the proximal end of the female duct. The female duct (Fig. 12D, 12F & 13A: fd) opens into the receptacle bursa (terminology of Karling 1981; followed by Reygel et al. 2011) (Fig. 13A: rb) through a sphincter (Fig. 13A: sph). The caudally-located bursa (Fig. 12D, 12F & 13A: b) opens into the female genital atrium via the bursal stalk. The uterus (Fig. 13A: ut) has a sphincter more or less at its midpoint. The common gonopore (Fig. 13A: cg) opens at 90%., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on pages 476-478, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x","Karling, T. G. (1978) Anatomy and Systematics of Marine Turbellaria from Bermuda. Zoologica Scripta, 7, 25 - 248.","Reygel, P. C., Willems, W. R. & Artois, T. J. (2011) Koinocystididae and Gnathorhynchidae (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Galapagos, with the description of three new species. Zootaxa, 3096 (1), 27 - 40. https: // doi. org / 10.11646 / zootaxa. 3096.1.3"]}

Reinhardorhynchus Diez, Monnens & Artois gen. n. urn:lsid:zoobank.org:act: 02DC1CAC-6389-459E-B933-42E9647E307E Diagnosis. Representative of Koinocystididae with a proboscis with a juncture sphincter. Copulatory bulb of the conjuncta duplex-type, except in R. hexacornutus sp. n. which has a copulatory bulb of the divisa duplex-type. Copulatory organ with an armed or unarmed cirrus. Some species also with a papillary cirrus in the copulatory bulb and one to six accessory hooks distally. Etymology. In honour of the late Prof. Dr. Reinhard Rieger, for his enormous contribution to turbellarian research. Type species. Reinhardorhynchus riegeri (Karling, 1978) comb. n., here designated. Other species. Reinhardorhynchus anamariae sp. n., R. beatrizae sp. n., R. bispina (Karling, 1980) comb. n., R. curvicirra (Karling, 1980) comb. n., R. evelinae (Marcus, 1954) comb. n., R. hexacornutus sp. n., R. pacificus sp. n., R. renei (Reygel, Willems & Artois, 2011) comb. n., R. riae sp. n., R. ruffinjonesi (Karling, 1978) comb. n., R. scotica (Karling, 1954) comb. n., R. soror sp. n., R. tahitiensis sp. n., R. unicornis sp. n., and R. variodentata (Karling, Mack-Fira & Dörjes, 1972) comb. n., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on page 462, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Karling, T. G. (1978) Anatomy and Systematics of Marine Turbellaria from Bermuda. Zoologica Scripta, 7, 25 - 248.","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x","Marcus, E. (1954) Turbellaria Brasileiros (11). Papeis Avulsos, 11, 419 - 489. https: // doi. org / 10.11606 / issn. 2526 - 4877. bsffclzoologia. 1946.125301","Reygel, P. C., Willems, W. R. & Artois, T. J. (2011) Koinocystididae and Gnathorhynchidae (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Galapagos, with the description of three new species. Zootaxa, 3096 (1), 27 - 40. https: // doi. org / 10.11646 / zootaxa. 3096.1.3","Karling, T. G. (1954) Einige marine Vertreter der Kalyptorhynchien-Familie Koinocystididae. Arkiv for Zoologi, 7, 165 - 183.","Karling, T. G., Mack-Fira, V. & Dorjes, J. (1972) First report on marine microturbellarians from Hawaii. Zoologica Scripta, 1, 251 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00575. x"]}

Itaipusa novacaledonica Diez, Schockaert, Reygel & Artois sp. n. (Fig. 3) urn:lsid:zoobank.org:act: 9433D2B5-29ED-40E6-8DB3-7786947F4C94 Itaipusa n. sp. 2 in Tessens et al. (2014) Material and distribution. Observations on live specimens. Two whole mounts, one of which is designated holotype (FMNH https://id.luomus.fi/ KV.647), the other in HU (XIII.3.07), and one serially-sectioned specimen (HU XIII.3.08), collected in Anse Vata Bay (22°18’19”S; 166°26’50”E) (Type Locality), Nouméa, New Caledonia (October 22, 2003), on algae (Ulva -like) and sediment taken from rocks in the mouth of a small river. Etymology. Species named after New Caledonia, where the material was collected. Diagnosis. Species of Itaipusa with a cirrus with two longitudinal rows of triangular spines. One row is inverted U-shaped and ±136 μm long, the other is M-shaped and ±193 μm long. Spines ±3 μm long in both rows, slightly larger at one of the ends (±5 μm long). Distally, the male duct opens in a penis papilla, that is partially sclerotised. Description. The specimens are ± 1 mm long, translucent, with a pair of rounded eyes. Habitus and general morphology do not deviate from other species of Itaipusa described above. The proboscis is about 20% of the body length in the live specimens. Basophilic and eosinophilic glands open into the proboscis through its caudal wall. Two pairs of integument retractors were observed: a ventral and a dorsal one. Other muscles were not observed. The morphology of the pharynx does not differ from that of I. divae. It is located at 40% and its diameter is 15% of the body length. Three types of glands open in the distal part of the pharynx lumen: two eosinophilic ones (filled with a coarse-grained or a fine-grained secretion), and basophilic glands with a coarse-grained secretion. A pair of testes is located antero-lateral to the pharynx. Caudally from the pharynx the vasa deferentia form a pair of seminal vesicles. The seminal vesicles (Fig. 3A & 3C: sv) fuse to form the seminal duct just before entering the copulatory bulb. The seminal vesicles and seminal duct are lined by a nucleated epithelium and surrounded by an external longitudinal muscle layer. The atrial organs are located in the caudal body fourth. The copulatory bulb is 168–196 μm long (x̄ = 182 μm; n = 2) and surrounded by an external, longitudinal muscle layer and a thick, internal circular muscle layer. The seminal duct is situated in the proximal half of the copulatory bulb. Where the seminal duct opens into the cirrus, filiform prostate glands containing a coarse-grained eosinophilic secretion also enter the cirrus (Fig. 3A & 3C: pv). The armature of the cirrus (Fig. 3A–C: ci, 3D) consists of two longitudinal spiny rows: one row is M-shaped and 145–240 μm long (x̄ = 193 μm; n = 2) (Fig. 3B & 3D: spr1) and the other one is invert U-shaped and 134–138 μm long (x̄ = 136 μm; n = 2) (Fig. 3B & 3D: spr2). In both rows, the triangular spines are 2–4 μm long (x̄ = 3 μm; n = 2), reaching up to 5 µm at one of the ends. The rows of spines are conspicuous in the distal part of the cirrus, but less noticeable in the more proximal part. The copulatory bulb opens distally in a penis papilla (Fig. 3B: pp), which is partially sclerotised. A number of glands (Fig. 3B: gl) containing fine-grained eosinophilic secretion open distally into the penis papilla. The elongated ovaries (Fig. 3A: ov) lie beside the copulatory bulb. The oviducts open into the sperm-containing female duct. The female duct (Fig. 3A: fd) opens into the female atrium through a strong sphincter (Fig. 3A: sph1). The walls of the female atrium (Fig. 3A: fa) are weakly muscular. The bursal stalk (Fig. 3A: bs) is tubular in one specimen and swollen in a second one. It is surrounded by two strong and folded muscle layer consisting of external circular and internal longitudinal muscles. It connects with the caudally-located bursa (Fig. 3A: b), which is lined by feeble circular muscles. The uterus (Fig. 3A: ut) is oriented forward and is surrounded by a sphincter more or less in its midpart (Fig. 3A: sph2)., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on page 460, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"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"]}

Itaipusa divae Marcus, 1949 (Fig. 1A–C) Known distribution. Bahia de Santos (Type Locality) and Pitangueiras, São Sebastião, Brazil (see Marcus 1949 for details). Three localities in Galapagos Islands and several in Curaçao (see Reygel et al. 2011 for details). New records and material. Observations on live specimens. Three whole mounts from Siboney (19°57’34”N; 75°42’07”W), Santiago de Cuba, Cuba (February 7 & May 15, 2016; April 4, 2017) (HU XIII.2.42– XIII.2.44), intertidal up to 0.6 m deep, fine-grained sand, salinity 32–35 ‰. One whole mount from La Mula (19°56’44”N; 76°45’19”W), Guamá, Santiago de Cuba, Cuba (June 29, 2016) (HU XIII.2.45), intertidal rocky pools, on the algae Digenia simplex and Cladophoropsis macromeres, salinity 33 ‰. One whole mount from Macabí (20°54’13”N; 75°43’40”W), Banes, Holguín, Cuba (April 23, 2017) (HU XIII.2.46), fine-grained sand, 0.3 m deep, salinity 34 ‰. Three whole mounts from a beach east of the Marine Research Station of Achotines (07°24’47”N; 80°10’20”W), Vera Cruz, Panama (February 28, 2016) (USNM 1642500–1642502), just over the rocky hill, on green algae (Blidingia / Enteromorpha -like). One whole mount (HU XIII.2.47) and one serially-sectioned specimen (HU XIII.2.48) collected in Anse Vata Bay (22°18’19”S; 166°26’50”E), Nouméa, New Caledonia (October 22, 2003), on algae (Ulva -like) and sediment taken from rocks in the mouth of a small river. Remarks. Habitus and overall anatomical organisation of our specimens correspond to the description by Marcus (1949). The specimens are unpigmented, with two eyes. The specimens from Cuba are 0.8–1 mm long (x̄ = 0.9 mm; n = 5), the specimens from Panama are 0.9–1.3 mm long (x̄ = 1.1 mm; n = 2), and the specimen from New Caledonia is 1 mm long. The syncytial epidermis is 3 μm thick (in the serially-sectioned specimen from New Caledonia) and completely ciliated. Cilia 2–3 μm long. The epidermis has a thin basal lamina and is lined internally by a thick layer of circular muscles. Rhabdites present over the entire body surface, more numerous in the posterior body half, 2–3 μm long. The proboscis has the characteristic koinocystidid construction, with a strong juncture sphincter (see Brunet 1972; Karling 1980). It is 10% of the body length in live specimens from Panama and 15% in the specimens from Cuba and New Caledonia. The pharynx (Fig. 1A) is located in the anterior body half. Its diameter is 15% of the body length in live specimens from Panama and New Caledonia and 20% in specimens from Cuba. The prepharyngeal cavity (Fig. 1A: ppc) is lined by a low, nucleated epithelium (thicker in the distal 1/3 of the lumen) and surrounded by an external layer of longitudinal muscles. Four types of glands open very close to each other in the distal part of the pharynx lumen: two types containing a coarse-grained eosinophilic secretion, one stained yellowish (Fig. 1A: phg4) and the other stained brownish (Fig. 1A: phg1), one containing a fine-grained eosinophilic secretion (stained pinkish) (Fig. 1A: phg2), and one a coarse-grained basophilic secretion (stained dark blue-black) (Fig. 1A: phg3). Coarse-grained basophilic glands (Minot’s glands; Fig. 1A: oeg) open into the oesophagus (Fig. 1A: oe). The musculature of the pharynx consists of a layer of longitudinal muscles outside of the septum (Fig. 1A: lm), which is continuous with that surrounding the prepharyngeal cavity, and a circular one just inside of the septum (Fig. 1A: cm1). The distal opening of the pharynx is lined by a thick layer of longitudinal muscles, which in sagittal sections gives the impression of forming a lip-like structure (Fig. 1A: slm). The pharynx lumen is surrounded by a low epithelium and an outer layer of circular muscles (Fig. 1A: cm2) and an inner layer of longitudinal muscles (Fig. 1A: ilm). Radial muscles (Fig. 1A: rm) run between the internal and the external walls. The mouth (Fig. 1A: m) is surrounded by a sphincter (Fig. 1A: sph). The oviform copulatory bulb (Fig. 1B–C) is 76–86 μm long (x̄ = 81 μm; n = 5) in the specimens from Cuba, 86–89 μm long (x̄ = 88 μm; n = 2) in the specimens from Panama, and 130 μm long in the specimen from New Caledonia. The spiny cirrus as a whole (Fig. 1B–C: ci) is 35–41μm long (x̄ = 38 μm; n = 5) and 29–37 μm wide (x̄ = 33 μm; n = 2) in the specimens from Cuba, 20–36 μm long (x̄ = 29 μm; n = 3), and 28–44 μm wide (x̄ = 36 μm; n = 2) in the specimens from Panama, and 57 μm long and 36 μm wide in the specimen from New Caledonia. The cirrus is formed by transverse, sclerotised folds bearing tightly-packed spines. Spines are 2–3 μm long (x̄ = 2 μm; n = 25) in the specimens from Cuba and New Caledonia, and 3–4 μm long (x̄ = 4 μm; n = 25) in the specimens from Panama., Published as part of Diez, Yander L., Monnens, Marlies, Aguirre, Rosa Isabel, Yurduseven, Rana, Jouk, Philippe, Van Steenkiste, Niels W. L., Leander, Brian S., Schockaert, Ernest, Reygel, Patrick, Smeets, Karen & Artois, Tom, 2021, Taxonomy and phylogeny of Koinocystididae (Platyhelminthes, Kalyptorhynchia) with the description of three new genera and twelve new species, pp. 451-500 in Zootaxa 4948 (4) on pages 456-457, DOI: 10.11646/zootaxa.4948.4.1, http://zenodo.org/record/4629235, {"references":["Marcus, E. (1949) Turbellaria Brasileiros (7). Boletins da Faculdade de Filosofia Ciencias e Letras, Universidade de Sao Paulo Zoologia, 7 (14), 7 - 155. https: // doi. org / 10.11606 / issn. 2526 - 4877. bsffclzoologia. 1949.129106","Reygel, P. C., Willems, W. R. & Artois, T. J. (2011) Koinocystididae and Gnathorhynchidae (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Galapagos, with the description of three new species. Zootaxa, 3096 (1), 27 - 40. https: // doi. org / 10.11646 / zootaxa. 3096.1.3","Brunet, M. (1972) Koinocystididae de la region de Marseille. Zoologica Scripta, 1, 157 - 174. https: // doi. org / 10.1111 / j. 1463 - 6409.1972. tb 00673. x","Karling, T. G. (1980) Revision of Koinocystididae (Turbellaria). Zoologica Scripta, 9, 241 - 269. https: // doi. org / 10.1111 / j. 1463 - 6409.1980. tb 00666. x"]}