taxonID	type	description	language	source
6A06F520B30646009BBDD8FC200EF854.taxon	diagnosis	Diagnosis (Emended from Fonseca & Bezerra 2014): Xyalidae. Cuticle coarsely striated, vacuoles may be present. Amphideal fovea placed over or very close to the end of pharyngostome. Its shape is circular or oval and an amphideal plate may be present (amphideal plate was used to characterize the cuticle annules without division which accommodates the entire amphideal fovea). In some species, amphideal fovea of the males is different to that of the females (oval x circular). The buccal cavity is long and tubular, divided in two parts: cheilostome, short anterior chamber at the level of cephalic setae; pharyngostome, a narrow tubular part extending along the cervical region. Males with two testes. Spicules can be symmetrical or asymmetrical. Gubernaculum is present in most species and normally with apophysis. Precloacal supplements present or absent, when present, they are papilliform (not always easy to see). Females with reproductive system monodelphic prodelphic the left of intestine. Tail conical.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30646009BBDD8FC200EF854.taxon	type_taxon	Type species: Rhynchonema cinctum Cobb, 1920.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30446059BBDDEC820C5FF70.taxon	description	(Figures 1 – 4, Table 1)	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30446059BBDDEC820C5FF70.taxon	materials_examined	Material studied. Six males, three females. Glycerin slides. Type material. Holotype male (MOUFPE 0032), paratype female (MOUFPE 0033), other paratypes: 5 males (NM LMZOO-UFPE 504 – 508) and 2 females (NM LMZOO-UFPE 509 – 510). Type locality. Holotype male and paratype female: 5 º 01 ’ 34.8 ” S; 36 º 20 ’ 11.2 ” W (8 m depth). Potiguar Basin, located along the coast of the state of Rio Grande do Norte and the extreme west of the state of Ceará, in the Northeast region of Brazil. Collected in 2013. In sediments from rhodolith beds.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30446059BBDDEC820C5FF70.taxon	etymology	Etymology. The specific epithet ‘ laminam ’ is given to the species due to the presence of a large amphideal plate where its amphideal fovea is located.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30446059BBDDEC820C5FF70.taxon	description	Description. (Males). Body cylindrical 554 – 637 μm long. Maximum body diameter corresponding to 5 – 8 times the head diameter. Cuticle strongly annulated (making it difficult to visualize some internal structures). The annules are larger after the amphideal fovea, where vacuoles can be observed. Inversion of the cuticle annules in relation to its direction. From the cephalic region to the end of the intestine the annules are directed to the anterior part of the body, from the end of the intestine to the tip of the tail the annules are oriented towards the back region of the body. Arrangement of anterior sensilla not observed (probably lost during sample processing). Somatic setae long and fine, present along the entire body length. Amphideal fovea oval and elongated, accommodated on amphideal plate, occupying 100 % of corresponding body diameter, located 41 – 52 μm from the anterior end and presenting 29 – 32 anterior cuticular annules. Buccal cavity 51 – 57 μm long, elongated and narrow. The buccal cavity end is in the central region of the amphideal fovea. Nerve ring and secretory-excretory pore not observed (the same condition was observed in all analyzed specimens). Pharynx (165 – 186 μm long) without terminal bulb. Small cardia surrounded by the anterior portion of the intestine. Reproductive system with two anterior and extended testes, located to the left of the intestine. Spicules symmetrical, 11 – 14 μm long (1 time the cloacal body diameter), with proximal region slightly curved and cephalized, difficult to see (spicules appear poorly sclerotized and the thick cuticle increases the difficulty of visualization, the same condition was observed in all analyzed specimens). Gubernaculum occupying 23 – 54 % of spicules length, with a dorsal apophysis 4 – 6 μm long and pointed projection in its proximal portion facing the anterior region of the body. Two small precloacal papilliform supplements, that are difficult to visualize. Tail conical, about 4 – 4.6 times the cloacal body diameter. Three caudal glands present. Paratypes (Females). Similar to males. Body measuring 486 – 703 μm in length and maximum diameter of 15 – 20 μm. Sexual dimorphism of the amphideal fovea shape and size present. Females with circular amphideal fovea, accommodated on an elongated amphideal plate (8 – 10 μm long), occupying 50 – 60 % of corresponding body diameter, located at the end of pharyngostome, 34 – 59 μm (11 – 15 times head diameter) from anterior end. Cuticle has 28 – 32 annules anterior to the amphideal fovea. Buccal cavity similar to that of males (39 – 60 μm long). Nerve ring and secretory-excretory pore not observed. Reproductive system monodelphic prodelphic, with the ovary extended to the left of the intestine. Vulva located posterior to the middle region of the body at 349 – 499 μm from anterior end (71 – 76 % of body length). Tail conical, about 3.8 – 5.3 times anal body diameter.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30446059BBDDEC820C5FF70.taxon	diagnosis	Diagnosis. Rhynchonema laminam sp. nov. is characterized by an annulated cuticle with vacuoles and long somatic setae throughout the body, without distribution pattern. 23 – 32 annules anterior to the amphideal fovea. Sexual dimorphism in relation to the shape, oval, very elongated and large big amphideal fovea in males, occupying 100 % of the corresponding diameter; circular and smaller in females, occupying 50 – 60 % of the corresponding body diameter. Both sexes present an elongated amphideal plate (11 – 16 μm long in males and 8 – 10 μm in females). Spicules poorly sclerotized (1 time cloacal body diameter), with proximal region slightly curved and cephalized. Gubernaculum with dorsal apophysis and anteriorly pointed projection. Two very small papilliform precloacal supplements. Tail conical, 3.8 – 5.3 times cloacal or anal body diameter. Differential diagnosis. Rhynchonema laminam sp. nov. is differentiated from other species of the genus by a combination of characteristics: presence of the amphideal plate, sexual dimorphism in the morphology and size of the amphideal fovea, presence of cuticle vacuoles, spicules and gubernaculum shape and papilliform precloacal supplements. The species that most resembles Rhynchonema laminam sp. nov. is Rhynchonema collare, in the presence of the amphideal plate (described by Nicholas & Stewart 1995 as “ amphids separated by strong nonannulated cuticle ”), amphideal fovea strongly dimorphic (longitudinally oval and occupying practically the entire corresponding body diameter in males, and much more smaller and circular in females), in addition to long somatic setae distributed throughout the body. However, R. collare presents asymmetrical spicules (morphology different from each other), while in the new species they are symmetrical. Furthermore, the gubernaculum is also different, in R. collare it presents a strong dorsocaudal apophysis (vs. in R. laminam sp. nov., gubernaculum with a dorsal apophysis with a pointed projection in its proximal portion facing the anterior region of the body). Additionally, the presence of vacuoles in the cuticle, as well as precloacal supplements were not mentioned in the description of R. collare, however, both characteristics are present in the new species. The presence of amphideal plate is also observed in Rhynchonema deconincki, Rhynchonema quemer and Rhynchonema scutatum. Nevertheless, R. quemer and R. deconincki, differ from the new species by the presence of a spiral structure in their amphideal fovea, and R. scutatum has a circular amphideal fovea in both sexes, although it is larger in the males, as in the new species (R. laminam sp. nov. has an oval elongated amphideal fovea in males and circular in females). Additionally, all have symmetry in their spicules, but R. quemer does not have a gubernaculum, R. deconincki has a small gubernaculum without apophysis, and R. scutatum has a gubernaculum with a poorly developed apophysis and a pointed anterior projection (R. laminam sp. nov. has a gubernaculum with a dorsal apophysis and a pointed anterior projection).	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30E460F9BBDDE802184F8C4.taxon	description	(Figures 5 – 8, Table 2)	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30E460F9BBDDE802184F8C4.taxon	materials_examined	Material studied. five males, six females. Glycerin slides. Type material. Holotype male (MOUFPE 0034), paratype female (MOUFPE 0035), other paratypes: four males (NM LMZOO-UFPE 511 – 515) and five females (NM LMZOO-UFPE 516 – 520). Type locality. Holotype male and paratype female: 05 º 04 ’ 10.1 ” S; 36 º 22 ’ 31.1 ” W (4 m depth). Potiguar Basin, located along the coast of the state of Rio Grande do Norte and the extreme west of the state of Ceará, in the Northeast region of Brazil. Collected in 2013. In sediments from rhodolith beds.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30E460F9BBDDE802184F8C4.taxon	etymology	Etymology. The specific epithet ‘ potiguar ’ is given due to its occurrence having been recorded along different points of the Potiguar Basin, coast of Northeast of Brazil.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30E460F9BBDDE802184F8C4.taxon	description	Description. (Males). Body cylindrical 742 – 883 μm long. Maximum body diameter corresponding to 4 – 6 times the head diameter. Annulated cuticle, with wider annules on the anterior portion of the body (these annules are wider towards the end of the pharynx compared to the annules along the body length). Cuticle annules inversion observed. The part that starts in the cephalic region until the end of the pharynx presents a homogeneous pattern facing the anterior part of the body. The inversion and direction that the cuticle annules present can be better analyzed in the region that extends from the cloaca to the tail, facing posterior body. In the cephalic sensilla arrangement only six cephalic setae were visualized. Somatic setae throughout the body, with no distribution pattern (setae are short and fine). Amphideal fovea circular, occupying 61 – 69 % of corresponding body diameter (the equivalent of three body annules width). It is located at the end of the pharyngostome (43 – 50 μm from anterior end), presenting 18 – 21 anterior cuticular annules. Buccal cavity 49 – 52 μm long and narrow. Nerve ring and secretory-excretory pore not observed (the same condition was observed in all analyzed specimens). Pharynx (218 – 235 μm long) without terminal bulb. Cardia present, apparently partially involved by the intestine. Reproductive system with a pair of testes, located in the anterior and left portion of the intestine. Spicules symmetrical, arc shaped and with a proximal region spoonlike (1 – 2 times the cloacal body diameter, spicules appear quite sclerotized). Gubernaculum occupying 30 – 36 % of spicules length, with a dorsal-caudal apophysis measuring 11 – 13 μm long. Presence of three precloacal papilliform supplements, slightly sclerotized (which makes visualization very difficult). Tail conical, about 3.4 – 4.2 times the cloacal body diameter (the annules in this region are quite thin compared to those on the anterior portion of the body). Caudal glands not visualized. Paratypes (Females). Very similar to males. Body measuring 754 – 810 μm in length and maximum diameter 28 – 37 μm. Sexual dimorphism in the shape of the amphideal fovea absent. Amphideal fovea circular, smaller than in the males (39 – 44 % of corresponding body diameter), accommodated in two annules (the cuticle annule at the level of the amphideal fovea appears to widen to accommodate almost the entire length of the amphideal fovea, but when looking at the ventral or dorsal region of the body, the amphideal fovea occupies a length equivalent to two annules). Amphideal fovea is located 48 – 56 μm (10 – 11 times head diameter) from anterior end, where there are 21 – 22 annules before it. Buccal cavity similar to that of males, but longer (53 – 58 μm). Nerve ring and secretory-excretory pore not observed. Reproductive system is monodelphic prodelphic, with ovary located to the left of the intestine. Vulva located 539 – 589 μm from anterior end (71 – 74 % of body length), with a specific shape similar to a “ leaf ” that aids in its visualization. Tail conical about 4.5 – 5 times anal body diameter. Three caudal glands present.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30E460F9BBDDE802184F8C4.taxon	diagnosis	Diagnosis. Rhynchonema potiguar sp. nov. is characterized by an annulated cuticle with somatic setae throughout the body, with no distribution pattern. The annules are wider in the anterior portion of the body up to 2 / 3 of the pharynx. 18 to 22 cuticular annules anterior to the amphideal fovea. Sexual dimorphism in relation to the fovea shape absent. Amphideal fovea circular, slightly larger in males, occupying the equivalent to three annules width in males (61 – 69 % corresponding body diameter). In females, it corresponds to 39 – 44 % of the body diameter and it occupies the equivalent length of two annules of the cuticle, although it is possible to see in the lateral region that one of the annules widens and accommodates practically the entire length of the amphideal fovea. Spicules are arched and have a spoon-shaped proximal portion. Gubernaculum with a developed dorsal-caudal apophysis. Three precloacal papilliform supplements. Female with leaf-shaped sclerotization in the vaginal region. Tail conical corresponding to 3.4 – 5 cloacal or anal body diameter. Differential diagnosis. Rhynchonema potiguar sp. nov. differentiates from other species of the genus by the presence of the circular amphideal fovea, where sexual dimorphism is not very evident, with a slightly larger amphideal fovea in males, spicules and gubernaculum apophysis morphology, in addition to the presence of precloacal supplements. The species that most resemble Rhynchonema potiguar sp. nov., are Rhynchonema annulatum, Rhynchonema brevituba and Rhynchonema gerlachi. These species have similar amphideal fovea (circular) morphology, which are slightly larger in males and located at the end of the pharyngostome. Additionally, somatic setae are present spaced along the body, symmetrical spicules and gubernaculum with the presence of an apophysis. Nevertheless, spicules and gubernaculum morphologies are divergent. R. annulatum has slender and shorter spicules (19 – 20 μm long), slightly curved ventrally with small capitulum and gubernaculum with the anterior part surrounding distal portion of the spicules, together with the presence of the handle-shaped dorsal-caudal apophysis. R. brevituba has shorter spicules (22 μm long), nearly perpendicular curvature (L-shaped) and gubernaculum with dorsal apophysis. R. gerlachi spicules are also shorter (21 μm long) with swollen proximal end and bifurcated distal end, gubernaculum with rectangular dorso-caudal apophysis (vs. in R. potiguar sp. nov. spicules larger in relation to the three species with a length of 34 – 37 μm, presenting a curved, cephalized and spoon-shaped proximal region, presenting gubernaculum with a dorso-caudal apophysis). Additionally, none of the species have pre-cloacal supplements, a characteristic present in the new species.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30846109BBDDE802176F973.taxon	description	(Figures 9 – 12, Table 3)	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30846109BBDDE802176F973.taxon	materials_examined	Material studied. Four males, four females. Glycerin slides. Type material. Holotype male (MOUFPE 0036), paratype female (MOUFPE 0037), other paratypes: three males (NM LMZOO-UFPE 521 – 523) and three females (NM LMZOO-UFPE 524 – 526). Type locality. Holotype male and paratype female: 5 º 01 ’ 34.8 ” S; 36 º 20 ’ 11.2 ” W (8 m depth). Potiguar Basin, located along the coast of the state of Rio Grande do Norte and the extreme west of the state of Ceará, in the Northeast region of Brazil. Collected in 2012. In sediments from rhodolith beds.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30846109BBDDE802176F973.taxon	etymology	Etymology. The specific epithet ‘ cleoae ’ is given with great pleasure to this species, in honor of the niece of the first author, called Cléo Luisa de Macedo Lima.	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30846109BBDDE802176F973.taxon	description	Description. (Males). Body cylindrical 537 – 684 μm long. Maximum body diameter corresponding to 6 – 8 times the head diameter. Clearly annulated cuticle presenting vacuoles (the annules closest to the amphideal fovea region are wider compared to the rest of the body, the vacuoles are best observed in this region). Inversion in the direction of the annules and longitudinal projections, the annules between the cephalic region and the middle portion of the intestine face the anterior region of the body, and the annules between the intestine and the tail face the posterior region. Only the outer labial setae were visualized. Amphideal fovea oval occupying the equivalent of four body annules in length, 47 – 53 % of corresponding body diameter. Amphideal fovea located the end of pharyngostome (52 – 62 μm from anterior end), with 30 – 34 cuticular annules anterior to it. Buccal cavity tubular, long and narrow, with 52 – 61 μm in length). Nerve ring and secretory-excretory pore not observed (the same condition was observed in all analyzed specimens). Pharynx cylindrical (137 – 171 μm long), without terminal bulb. Cardia slightly rounded, involved by the intestine. Reproductive system with two testes located anterior and to the left of the intestine. Spicules symmetrical, 17 – 24 μm long (1 time the cloacal body diameter), thin and without great curvature, almost in a straight line (the spicules are poorly sclerotized). Gubernaculum occupying 24 – 34 % of spicules length, presenting a singular projection in the form of a V, measuring 6 – 9 μm long. Apophysis absent. Precloacal supplements absent. Tail conical, about 4 – 5 times the cloacal body diameter. Caudal glands absent. Paratypes (Females). Very similar to males. Body measuring 552 – 836 μm in length and maximum diameter 19 – 32 μm. Inversion of the annules is located at the level of the vulva, the annules in the anterior region of the body (anterior to the vulva) facing upwards, and the annules located posterior to the vulva face downwards. Sexual dimorphism of the amphideal fovea present. Females with a circular amphideal fovea, occupying the equivalent of three body annules in length, 47 – 53 % of corresponding body diameter, located 46 – 63 μm (14 – 20 times head diameter) from anterior end (32 – 33 annules distance from anterior region). Buccal cavity similar to that of males, but shorter (47 – 63 μm long). Nerve ring and secretory-excretory pore not observed. Reproductive system is monodelphic prodelphic, formed by a single anterior ovary lying to the left of the intestine. Vulva located 393 – 582 μm from anterior end (70 – 72 % of body length). Tail conical, about 3.8 – 4.4 times anal body diameter (the annules in this region have a smaller distance between one to the other).	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
6A06F520B30846109BBDDE802176F973.taxon	diagnosis	Diagnosis. Rhynchonema cleoae sp. nov. is characterized by annulated cuticle with longitudinal projections and wider anterior annules, with vacuoles present. Buccal cavity more elongated. 30 to 34 annules anterior to the amphideal fovea. Sexual dimorphism in the amphideal fovea, in males it is oval-elongated, occupying equivalent to four annules and circular in females, occupying three annules. Amphideal fovea 47 – 53 % of the corresponding body diameter in both sexes. Spicules thin and without great curvature (1 cloacal body diameter). Gubernaculum with projection in the form of a V. Two testes in the anterior and left portion of the intestine. Tail conical, corresponding to 3 – 5 cloacal or anal body diameter. Differential diagnosis. Rhynchonema cleoae sp. nov. differs from other species of the genus by the presence of the amphideal fovea with sexual dimorphism related to the shape (oval-elongated in males vs circular in females, but similar in relation to diameter), cuticle with vacuolization, spicules and gubernaculum morphology. The species that most resemble Rhynchonema cleoae sp. nov., are Rhynchonema falciferum, Rhynchonema sieverti and Rhynchonema pulchrum, due to similarities in the shape of the amphideal fovea and the presence of sexual dimorphism (amphideal fovea oval and larger in males, circular and smaller in females); position of the amphideal fovea in relation to the anterior end of the body (varying between 46 – 62 μm), symmetry of the spicules and presence of gubernaculum. Nevertheless, neither of these species have vacuoles as seen in the new species and the position of the amphideal fovea in relation to the pharyngostome is divergent. In R. falciferum it is located before the end of the pharyngostome. In R. sieverti located posterior to the final portion of the pharyngostome and in R. pulchrum, as well as in the new species described, located at the end of pharyngostome. Furthermore, the species differ in terms of spicules morphology. R. falciferum, as well as the new species, has straight spicules, however, it has a gubernaculum with a dorsal apophysis. R. pulchrum has spicules curved with a proximal region cephalated; gubernaculum with apophysis paddle-like, dorsally oriented. R. sieverti has curved spicules and gubernaculum with narrow dorsal apophysis (vs. R. cleoae sp. nov. with thin spicules that are not curved, with a V-shaped gubernaculum and apophysis absent). Additionally, Rhynchonema kikuchii also presents vacuolation in the cuticle, morphology of the amphideal fovea is oval, similar number of annules anterior to the amphideal fovea (32 – 37 in R. kikuchii and 30 – 34 in R. cleoae sp. nov.) and location of the amphideal fovea before the end of the pharyngostome. However, R. kikuchii has asymmetrical spicules, a gubernaculum with the presence of a posterodorsal apophysis (vs. R. cleoae sp. nov. symmetrical spicules and gubernaculum without apophysis).	en	Mota, Juliana Thays, Neres, Patrícia Fernandes, Esteves, André Morgado (2025): Three new species of Rhynchonema (Monhysterida: Xyalidae) from the Brazilian continental shelf, Potiguar Basin. Zootaxa 5604 (3): 285-308, DOI: 10.11646/zootaxa.5604.3.4, URL: https://doi.org/10.11646/zootaxa.5604.3.4
