taxonID	type	description	language	source
039A6B12FF9BBF66FC5AFEB1E31DBC46.taxon	diagnosis	Diagnosis Stilbonematinae Desmodoridae, with short, unarmed pharynx; minute buccal cavity; pharynx three partite, corpus may be distinctly muscular and swollen, thin isthmus containing nuclei, bulbus round, muscular or mainly glandular; cuticle finely transversely striated or coarsely annulated; amphidial fovea spiral, loop shaped or reduced to a porus; cuticle covered by ectosymbiotic sulphur-oxidizing chemoautotrophic gamma proteobacteria. Emended diagnosis of the genus Robbea Stilbonematinae; body long (L = 2.8 – 8.3 mm), slender (a> 110), cuticle thin, transverse striation extremely fine, cephalic capsule with block layer, creating a honey-comb structure in surface view; first circle of cephalic sensillae as six finger-like papillae retracted into mouth opening, second circle as six conical papillae (<1 µm long) at margin of buccal membrane in lateral and submedian positions; four long cephalic setae in sublateral position, directed anteriorly, close to the anterior margin of the amphidial fovea; one circle of eight subcephalic setae with four in submedian position (either at about the level of the cephalic setae or at the level of the centre of the amphidial fovea) and four sublateral near the posterior margin of the amphidial fovea. Somatic setae minute or absent, except for subventral rows of papilliform setae on the male tail, instead eight rows of cuticular pores corresponding to the GSOs; GSOs in eight rows, two sublateral rows on each side and two submedian rows dorsally and ventrally, respectively. GSOs dark-purple coloured in live animals only. Amphidial fovea flat with shallow spiral groove, ventrally wound. Pharynx with distinctly swollen muscular corpus, distinctly set off from the long and thin isthmus, small mainly glandular terminal bulb. Spicules curved, cephalate, capitulum appearing heart-shaped under the light microscope, gubernaculum with paired dorsocaudally directed plate-shaped apophysis with reinforced margin; tail cylindro-conical. Vulva with conspicuous sclerotization. Dense monolayer of ectosymbiotic coccobacilli attached to the cuticle, starting several pharynx-lengths from anterior end to near tip of tail. Body diameter decreases at onset of bacterial coat, accommodating the thickness of the symbiont layer. Bacteria arranged with their longer axis parallel to the nematode’s cuticle, dividing transversally (see Figs 2 for an overview of host and symbiont characteristics).	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9BBF66FC5AFEB1E31DBC46.taxon	discussion	Remarks: Whether the dark coloration of the GSOs can be used as a genus character is unclear. The lack of coloration in all species that had not been observed live is most probably due to the fixation and processing of the nematodes prior to observation, which leads to a fading of the colour. This underlines the importance of observation of live material in the study of meiofauna.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9BBF66FC5AFEB1E31DBC46.taxon	description	The following specimens are tentatively assigned to the genus Robbea:	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FEDCFD24E47CBC7C.taxon	description	ZooBank registration: http: // zoobank. org: urn: lsid: zoobank. org: act: EB 683064 - 846 B- 4747 - 8431 - E 10 DD 10 EFC 2.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FEDCFD24E47CBC7C.taxon	materials_examined	Type location: Carrie Bow Cay, Belize; back-reef sand patch north of the island, 2 m depth. Coordinates: 16.803371 N, 88.082003 W. Type material: One holotype (NHMW-ZOO-EV-M- 5863), four paratypes male (NHMW-ZOO-EV-M- 5864 / 1 - 4), three paratypes female (NHMW-ZOO-EV-M- 5865 / 1 - 3). Collection date: April 2013. Collector: J. A. Ott. Other material: Several specimens in J. A. Ott collection.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FEDCFD24E47CBC7C.taxon	distribution	Distribution: Regularly in all shallow, subtidal, back-reef sands around Carrie Bow Cay.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FEDCFD24E47CBC7C.taxon	etymology	Etymology: The species is dedicated to Judith Zimmermann, who contributed significantly to the study of Stilbonematinae.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FEDCFD24E47CBC7C.taxon	description	Description: With the characters of the genus. Measurements see Supporting Information, Table S 2. Large, slender species (Figures 3 – 5), live specimens with conspicuously dark-coloured GSOs. Males with prominent ventral GSOs in post-pharyngeal region that protrude as 16 – 18 bumps when the worm’s body is bent ventrally. Cephalic capsule extending over 55 – 60 % of corpus. Corpus of the pharynx less than 25 % of pharynx length, isthmus very long occupying 61 – 67 % of pharynx, bulbus small, glandular. Tail conical with rounded tip. Symbiotic bacteria short rods, 2 × 1 µm.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FB85FB52E58EBDC4.taxon	description	ZooBank registration: http: // zoobank. org: urn: lsid: zoobank. org: act: 35 EFD 783 - FDBC- 4 C 54 - B 9 B 7 - DDE 69 CABA 765.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FB85FB52E58EBDC4.taxon	materials_examined	Type location: Bay of Sant’ Andrea, Elba, Italy; subtidal sand in 5 – 6 m depth. Coordinates: 42.808342 N, 10.141764 E. Type material: One holotype (NHMW-ZOO-EV-M- 5869), three paratypes female (NHMW-ZOO-EV-M- 5870 / 1 - 3). Collection date: April 2016. Collector: F. Scharhauser.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FB85FB52E58EBDC4.taxon	etymology	Etymology: The species is dedicated to Christian Lott, scientist and underwater film-maker at the Hydra Marine Station, Elba.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FB85FB52E58EBDC4.taxon	description	Description: With the characters of the genus. Measurements see Supporting Information, Table S 2. Shorter (L <7 mm) and stouter than the foregoing species (Figures 8 and 9). Cephalic capsule long, extending over> 60 % of corpus. Corpus about 25 % of pharynx length, isthmus short with 47 – 54 %, bulbus large, round, occupying one-fifth of the pharynx. Cuticle finely striated, striae 0.6 µm wide. Vulva distinctly cuticularized, but less so than in the forgoing species. Tail conical with a distinctly ‘ pipette’ - shaped tip. Symbiotic bacteria rods, 3 × 1.5 µm.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FED0F90FE260BEA3.taxon	description	ZooBank registration: http: // zoobank. org: urn: lsid: zoobank. org: act: 00 CF 1524 - 8 B 96 - 40 F 2 - 8 A 40 - EC 4 AEC 20 BD 99.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FED0F90FE260BEA3.taxon	materials_examined	Type location: Bay of Sant’ Andrea, Elba, Italy; subtidal sand in 5 – 6 m depth. Coordinates: 42.808342 N, 10.141764 E. Type material: One holotype (NHMW-ZOO-EV-M- 5866), five paratypes male (NHMW-ZOO-EV-M- 5867 / 1 - 5), two paratypes female (NHMW-ZOO-EV-M- 5868 / 1 - 2). Collection date: April 2016. Collector: F. Scharhauser. Other material: Several specimens in J. A. Ott collection.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FED0F90FE260BEA3.taxon	etymology	Etymology: The species is dedicated to Miriam Weber, scientist and our host at the Hydra Marine Station, Elba.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9EBF64FED0F90FE260BEA3.taxon	description	Description: With the characters of the genus. Measurements see Supporting Information, Table S 2. Large (L> 7 mm), extremely slender (a> 200) species, females with much shorter tail than males (Figures 6 and 7). Post-pharyngeal ventral GSO enlarged but not protruding. Cephalic capsule extending over 55 – 60 % of corpus. Corpus about 25 % of pharynx length, isthmus 60 – 63 %, bulbus 13 – 17 %. Cuticle extremely finely striated, striae 0.4 µm wide. Vulva strongly cuticularized. Tail conical with rounded tip. Symbiotic bacteria rods, 2.3 – 2.6 X 1 µm.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9FBF65FED7FA31E584BCBD.taxon	description	ZooBank registration: http: // zoobank. org: urn: lsid: zoobank. org: act: 5 B 3 D 9322 - A 4 D 5 - 44 FB- 8 B 55 - B 45 FC 258 C 271.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9FBF65FED7FA31E584BCBD.taxon	materials_examined	Type location: Yakata, Okinawa, Japan; shallow subtidal sand. Coordinates: 26.4926 N, 127.842126 E. Type material: One holotype (NHMW-ZOO-EV-M- 5871), three paratypes male (NHMW-ZOO-EV-M- 5872 / 1 - 3). Collection date: Dec. 2017. Collector: B. Seah. Other material: Several specimens in J. A. Ott collection.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9FBF65FED7FA31E584BCBD.taxon	etymology	Etymology: The species is dedicated to Brandon Seah, marine scientist who collected the worms.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9FBF65FED7FA31E584BCBD.taxon	description	Description: With the characters of the genus. Measurements see Supporting Information, Table S 2. Small (<6 mm long) and slender species (Figures 10 and 11). Males with prominent, enlarged GSO in ventral post-pharyngeal region, protruding as 17 – 20 bumps. Subcephalic setae almost as long as cephalic setae. Cephalic capsule short, extending over about 50 % of corpus. Corpus occupying about 25 % of pharynx length, isthmus long (> 60 %), very small, round, glandular bulbus. Small somatic setae distributed over body. Tail conical with pointed tip. Symbiotic bacteria slender rods, 3,7 × 1.5 µm.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9FBF6AFC7FF94EE309BC33.taxon	description	ZooBank registration: http: // zoobank. org: urn: lsid: zoobank. org: act: 3585 C 810 - E 79 D- 4 E 8 C-A 534 - B 6 FE 6 AB 23 F 14.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9FBF6AFC7FF94EE309BC33.taxon	materials_examined	Type location: Punta, BayBay, Leyte, Philippines; intertidal, fine sand next to mangrove stand. Coordinates: 10.642584 N, 124.774708 E. Type material: One holotype (NHMW-ZOO-EV-M- 5873), one paratype male (NHMW-ZOO-EV-M- 5874). Collection date: June 1996. Collector: J. A. Ott.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9FBF6AFC7FF94EE309BC33.taxon	etymology	Etymology: The species is dedicated to Bernardita Germano-Pilapil, former student of J. A. Ott, native of Leyte, Philippines, who helped with collection of specimens.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF9FBF6AFC7FF94EE309BC33.taxon	description	Description: With the characters of the genus. Measurements see Supporting Information, Table S 2 (excel sheet). Very small (<< 6 mm long) and rather stout species (Figures 12 and 13). Amphids more distinctly spiral than in other species. Males with prominent enlarged GSO in ventral post-pharyngeal region, protruding as 19 bumps. The species is remarkable for small (2 µm long) setae situated close to the submedian subcephalic setae. Cephalic capsule very long, extending over> 70 % of corpus. Long corpus occupies up to a third of pharynx length, large bulbus and consequently a very short isthmus (48 – 55 % of pharynx length). Sparse somatic setae. Tail conical with rounded tip. Male testis with conspicuous large, round cells (sperm?). Symbiotic bacteria coccobacilli, 1.3 × 1 µm.	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF93BF6CFC5CF8D3E2C2BE73.taxon	diagnosis	Genus diagnosis Stilbonematinae; body stout (a <110), cuticle finely striated, cephalic capsule with block layer; first circle of cephalic sense organs as six finger-like papillae retracted into mouth opening, second circle as six conical papillae (<1 µm long) at margin of buccal membrane in lateral and submedian position; four long cephalic setae in sublateral position, directed anteriorly, close to the anterior margin of the amphidial fovea; two or three circles of eight subcephalic setae each, with four in submedian position and four sublateral, the first close to the cephalic setae. Somatic setae present, of variable length; GSOscolourless, ineightrows, twosublateralrowsoneachsideand two submedian rows dorsally and ventrally, respectively. Amphidial fovea variable in shape, with spiral or loop-shaped groove, ventrally wound pharynx with strongly swollen muscular corpus, distinctly set off from the isthmus, terminal bulbus mainly glandular. Spicula curved, cephalate, capitulum not heart-shaped, gubernaculum variable in shape, with or without apophysis; males with ventral row of 11 – 19 sucker-like supplements in post-pharyngeal region, tail conical or cylindro-conical. Dense monolayer of ectosymbiotic rods or coccobacilli attached to the cuticle, starting at the posterior margin of the cephalic capsule or at a distance from the anterior end to near tip of tail. In most species, bacteria arranged with their longer axis perpendicular to the nematode’s cuticle, divide longitudinally (see Fig. 18 for host and symbiont characteristics).	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF93BF6CFC5CF8D3E2C2BE73.taxon	type_taxon	• Cyathorobbea tenax nov. comb. (type species)	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
039A6B12FF93BF6CFC5CF8D3E2C2BE73.taxon	discussion	Remarks: The taxonomic position of Robbea gerlachi Boucher 1975 is uncertain. The second circle of long subcephalic setae and the value of a <110 suggests a placement within Cyathorobbea; the shape of the head, however, is similar to Robbea species. Since the species is known from preserved females and juveniles only, the decisive character of the sucker-like supplements in males cannot be determined. The specimen described as Robbea tenax in Hopper and Cefalu (1973) differs in morphometric characteristics from the original description by Gerlach, 1963 (see PCA, Fig 19). We therefore propose it to be a different species and assign it the name " hopperi ".	en	Scharhauser, Florian, Saavedra, Daniel E. M., Pröts, Philipp, Ot, Jörg A., Geier, Benedikt, Gruber-Vodicka, Harald R., Polikarpov, Maxim, Bourenkov, Gleb, Leisch, Nikolaus (2025): Revision of the genus Robbea (Stilbonematinae: Desmodoridae), worldwide abundant marine nematodes with chromophoric Fe-Br inclusions and the description of a new stilbonematine genus. Zoological Journal of the Linnean Society 203 (1): 1-28, DOI: 10.1093/zoolinnean/zlae005, URL: https://doi.org/10.1093/zoolinnean/zlae005
