Enoploides Ssaweljev , 1912

De Souza, João V. & Maria, Tatiana F., 2023, Taxonomic review of Thoracostomopsidae (Nematoda, Enoplida): state of the art, list of valid species and dichotomous keys, Zootaxa 5361 (4), pp. 463-496 : 467-470

Genus Enoploides Ssaweljev, 1912

Syn. Labyrinthostoma Cobb, 1898 (nomen nudum)

The genus Enoploides was erected by Ssaweljev (1912) with the description of four species: Enoploides murmanicus Ssaweljev, 1912 , Enoploides tridentatus Ssaweljev, 1912 , Enoploides pellucidus Ssaweljev, 1912 and Enoploides typicus Ssaweljev, 1912 . This genus is characterized by its solid mandibles bearing two lateral bars converging/ fusing together to form a single rod for most of its length. Subsequently, other four species were described by Filipjev (1918): Enoploides brevis Filipjev, 1912 , Enoploides amphioxi Filipjev, 1912 , Enoploides cirrhatus Filipjev, 1912 and Enoploides hirsutus Filipjev, 1912 . This author also transferred Enoplus labiatus (B̧tschli, 1874) Filipjev, 1912 to Enoploides and provided an identification key for the nine known species at that time. Filipjev (1921) transferred Enoplus labrostriatus ( Southern, 1914) Filipjev, 1921 and Filipjev (1927) transferred Enoplolaimus cephalophorus ( Ditlevsen, 1918) Filipjev, 1927 both to this genus, and Enoploides saveljevi Filipjev, 1927 was described. Until middle of last century, four more species were added to the genus: Enoploides fluviatilis Micoletzky, 1923 ; Enoploides durapelle Kreis, 1929 ; Enoploides tyrrhenicus Brunetti, 1949 and Enoploides brunetti Gerlach, 1953 . Wieser (1953) reviewed the genus, indicating Enoploides italicus ( Steiner, 1921) , Enoploides longisetosus ( Schuurmans Stekhoven, 1943) , Enoploides balticus ( Schuurmans Stekhoven, 1935) , Enoploides macrochaetus ( Allgén, 1929) and Enoploides sabulicola ( Allgén, 1933) as doubtful species and described four other new species: Enoploides brattstr ̂mi Wieser, 1953, Enoploides paralabiatus Wieser, 1953 , Enoploides reductus Wieser, 1953 and Enoploides longicaudatus Wieser, 1953 . He also provided an identification key for 11 valid species at that time and transferred E. durapelle to Epacanthion . After that, E. murmanicum and E. pellucidus were transferred to Hyalacanthion , and later Inglis (1966) synonymized Hyalacanthion with Epacanthion . In the last century, 11 species were described to this genus and among these species, Enoploides tridentatus , Enoploides brevis , Enoploides brattstromi Wieser, 1953 , Enoploides paralabiatus Wieser, 1953 , Enoploides reductus Wieser, 1953 , Enoploides longicaudatus Wieser, 1953 , Enoploides labiatus (Butschli, 1874) Filipjev, 1918 , Enoploides oligochaetus Mawson, 1956 , Enoploides pterognathus Mawson, 1956 and Enoploides kerguelense Mawson, 1958 were invalidated by Wieser & Hopper (1967) who reviewed this genus, proposing an identification key for the six species that have s-shaped gubernaculum. They also did not agree with the synonymy of E. labiatus and Enoploides spiculohamatus Schulz, 1932 , future studies reinforced the validity of these two species which are similar to Enoploides longispiculosus Vitiello, 1967 by the gubernaculum shape ( Jeong et al. 2020). Later, Greenslade & Nicholas (1991) transferred Enoplolaimus crassus ( Ditlevsen, 1926) Greenslade & Nicholas 1991 , Enoplolaimus incurvatus ( Ditlevsen, 1926) Greenslade & Nicholas, 1991 , and Epacanthion filicaudatum ( Mawson, 1956) Greenslade & Nicholas, 1991 to this genus. Enoploides koreanus were the most recently described species and Jeong et al. (2020) provided an identification key including all 27 current known species, which compared the diagnostic characters of all valid species within the genus. Jeong et al. (2020) also comments on the species Enoploides uniformis Pavljuk, 1984 saying that Pavljuk has never described this species and may be a misspelling of Enoploides rimiformis Pavljuk, 1984 , which was included as a valid species from paper to paper for many years. Our taxonomic key is mainly based on the Jeong’s key ( Jeong et al. 2020) and differs from it because all presented branches are dichotomic.

Diagnosis from Jeong et al. (2020): Lips high and striated. Buccal cavity with three well-developed solid mandibles with claw-like anterior; mandible not extremely slender (ratio length/width <6 μm); three onchia shorter than the mandibles. Some species showing sexual dimorphism with pilosity either along the body or within the head region. Spicules usually long, some short, armed with either complex s-shaped/simple non s-shaped gubernaculum. Some species with precloacal supplement/papillae or postanal papillae/cuticular element of different form, at varying distances from the cloacal opening. Terminal setae observed at tail tip in some species. Mostly marine, with two freshwater species ( Enoploides fluviatilis and Enoploides stewarti Nicholas, 1993 ).

Number of valid species: 27

1. Enoploides amphioxi Filipjev, 1918 (Black Sea, Russia)

2. Enoploides bisulcus Wieser & Hopper, 1967 (Kay Biscayne, Florida, USA)

3. Enoploides brunettii Gerlach, 1953 (Mediterranean)

Syn. Enoploides brunettii vectis Gerlach, 1957a

4. Enoploides caspersi Riemann, 1966 (Elbe estuary, North Sea, Germany)

5. Enoploides cephalophorus ( Ditlevsen, 1918) Filipjev, 1927 (Kattegat, Denmark)

Syn. Enoplolaimus cephalophorus Ditlevsen, 1918

Enoploides cephalophorus tarvaensis Allgén, 1934

6. Enoploides cirrhatus Filipjev, 1918 (Sevastopol, Black Sea, Russia)

7. Enoploides crassus ( Ditlevsen, 1926) Greenslade & Nicholas, 1991 ( Jan Mayen, Norway)

Syn. Enoploides saveljevi Filipjev, 1927

Enoplolaimus crassus Ditlevsen, 1926

Epacanthion crassus Wieser, 1953

8. Enoploides delamarei Boucher, 1977 (Western Channel, France)

9. Enoploides disparilis Sergeeva, 1974 (Black Sea, Russia)

10. Enoploides fluviatilis Micoletzky, 1923 (Volga River, Russia)

11. Enoploides gryphus Wieser & Hopper, 1967 (Virginia Key, Florida, USA)

12. Enoploides harpax Wieser, 1959 (Seattle, Washington, USA)

13. Enoploides hirsutus Filipjev, 1918 (Sevastopol, Black Sea, Russia)

14. Enoploides incurvatus ( Ditlevsen, 1926) Greenslade & Nicholas, 1991 (Skagerrak, Sweden)

Syn. Enoploides incurvatus Schuurmans Stekhoven, 1946

Enoplolaimus incurvatus Ditlevsen, 1926

Epacanthion incurvatum Wieser, 1953

15. Enoploides koreanus Jeong, Tchesunov & Lee, 2020 (Jeju Island, South Korea)

16. Enoploides labiatus (B̧tschli, 1874) Filipjev, 1918 (North Sea)

Syn. Enoplus labiatus B̧tschli, 1874

17. Enoploides labrostriatus ( Southern, 1914) Filipjev, 1921 (Irish Coast of Atlantic)

Syn. Enoplus labrostriatus Southern, 1914

18. Enoploides longispiculosus Vitiello, 1967 (English Channel)

19. Enoploides mandibularis Coles, 1977 (Saldanha Bay, South Africa)

20. Enoploides polysetosus Jensen, 1986 ( East Flower Garden , NW Gulf of Mexico)

21. Enoploides ponticus Sergeeva, 1974 (Black Sea, Russia)

22. Enoploides rimiformis Pavljuk, 1984 (East Sea of Japan)

23. Enoploides spiculohamatus Schulz, 1932 (Kiel Bay, Germany)

24. Enoploides stewarti Nicholas, 1993 ( Lake Alexandrina , South Australia)

25. Enoploides typicus Ssaweljev, 1912 (White Sea)— type species

26. Enoploides tyrrhenicus Brunetti, 1949 (Mediterranean)

27. Enoploides vectis Gerlach, 1957a (Rio de Janeiro, Brazil)

Syn. Enoploides brunettii vectis Gerlach, 1957a

SPECIES INQUIRENDAE

1. Enoploides brattstroemi Wieser, 1953 (Gulf of Corcovado, Chile, lapsus brattstr ̂mi)

2. Enoploides brevis Filipjev, 1918 (Sevastopol, Black Sea, Russia)

3. Enoploides filicaudatum ( Mawson, 1956) Greenslade & Nicholas, 1991 ( Antarctica)

Syn. Epacanthion filicaudatum Mawson, 1956

4. Enoploides italicus ( Steiner, 1921) Filipjev, 1927 (no locality)

Syn. Enoplolaimus italicus Steiner, 1921

5. Enoploides kerguelensis Mawson, 1958 (Kerguelen Island, Antarctica)

6. Enoploides longicaudatus Wieser, 1953 (Gulf of Ancud, Chile)

7. Enoploides longisetosus Schuurmans Stekhoven, 1943 (Mediterranean)

8. Enoploides macrochaetus ( Allgén, 1929) De Coninck & Schuurmans Stekhoven, 1933 (Skagerrak, Sweden)

Syn. Enoplolaimus macrochaetus Allgén, 1929

9. Enoploides oligochaetus Mawson, 1956 ( Antarctica, lapsus oligotricha)

10. Enoploides paralabiatus Wieser, 1953 (Seno Reloncavi, Chile)

11. Enoploides pterognathus Mawson, 1956 ( Antarctica)

12. Enoploides reductus Wieser, 1953 (Gulf of Corcovado, Chile)

13. Enoploides sabulicola ( Allgén, 1933) Wieser, 1953 ( Norway)

Syn. Enoplolaimus sabulicola Allgén, 1933

14. Enoploides suecicus De Coninck & Schuurmans Stekhoven, 1933 ( Sweden)

Syn. Enoploides balticus Schuurmans Stekhoven, 1935

Enoplolaimus savaljevi Allgén, 1929 (lapsus ssaveljevi)

15. Enoploides tridentatus Ssaweljev, 1912 (White Sea)

NOMINA NUDA

1. Enoploides tyrannis Bussau, 1993 ( Peru basin)

2. Enoploides uniformis Pavljuk, 1984 (East Sea of Japan)

Key for males of Enoploides modified and updated from Jeong et al. (2020)

1: Spicules <150 µm; 2: Spicules> 150 µm; 3: Presence of a prominent precloacal supplement; 4: Absence of prominent precloacal supplement; 5: Precloacal supplement absent; 6: Precloacal supplement present; 7: Index c —9, spicules—35 µm long and gubernaculum without apophysis; 8: Index c —12–16, spicules—90 µm long and gubernaculum with weak apophysis; 9: Seven to eight precloacal supplement papillae in midline; 10: One precloacal supplement; 11: Tail <100 µm with two postanal papillae; 12: Tail> 100 µm; 13: Spicules—100 µm long with plate-like gubernaculum with weak apophysis and three terminal setae at tail tip; 14: Spicules—30–40 µm long with rod-like gubernaculum with a rounded head at distal end and no terminal setae at tail tip; 15: Gubernaculum not S-shaped; 16: Gubernaculum S-shaped; 17: Gubernaculum complex formed by multiple parts; 18: Gubernaculum short/small, weak, arcuate, plate; 19: Precloacal supplement <1 abd away from cloacal opening; 20: Precloacal supplement> 1.5 abd away from cloacal opening; 21: Precloacal supplement 1.5–1.7 abd away from cloacal opening; 22: Precloacal supplement> 2 abd away from cloacal opening; 23: Spicules <200 µm (<4 abd); 24: Spicules> 200 µm (> 4 abd); 25: Precloacal supplement S-curved; 26: Precloacal supplement not s-curved; 27: Cephalic setae <10 µm and buccal cavity extremely short (9 µm); 28: Cephalic setae> 20 µm and buccal cavity average; 29: Mandible with unique broad central expansion facing the buccal cavity; 30: Mandible generic in characteristic to the genus; 31: Proximal end of spicules funnel shaped; 32: Proximal end of spicules not funnel shaped, normally curved; 33: Asymmetrical spicules; 34: Symmetrical spicules; 35: Gubernaculum embracing the distal end of spicules, forming a short plate on each side; 36: Gubernaculum triangular, unpaired, flat, covering the spicules above and below; 37: Head globular; 38: Head non-globular; 39: Presence of cracks on mandibles; 40: Absence of cracks on mandibles; 41: Dorsal tooth missing; 42: Dorsal tooth present; 43: Distal end of spicules with mobile spine; 44: Distal end of spicules without mobile spine; 45: Gubernaculum with characteristic ventral knob; 46: Gubernaculum without characteristic ventral knob; 47: Spicules with diagonal reinforcement; 48: Spicules without diagonal reinforcement; 49: Spicules> 400 µm; 50: Spicules <300 µm; 51: Spicules—490 µm long and smooth, proximal end funnel shaped and distal end slightly expanded and pointed, index c —20; 52: Spicules—160–170 µm long, almost straight, index c —11–16.