Cyathorobbea, Scharhauser & Saavedra & Pröts & Ot & Geier & Gruber-Vodicka & Polikarpov & Bourenkov & Leisch, 2025

The genus Cyathorobbea gen. nov.

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 View Figure 18 for host and symbiont characteristics).

List of species

• Cyathorobbea tenax nov. comb. (type species)

Syn: Robbea tenax Gerlach 1963

• Cy. hopperi nom. nov.

Syn: R. tenax in Hopper and Cefalu 1973

• Cy. hypermnestra nov. comb.

Syn: R. hypermnestra Ott et al. 2014

• Cy. ruetzleri nov. comb.

Syn: R. ruetzleri Ott et al. 2014

• Cy. agricola nov. comb.

Syn: R. agricola Ott et al. 2014

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 View Figure 19 ). We therefore propose it to be a different species and assign it the name " hopperi ".