Bolbolaimus Cobb, 1920

Wen, Guo, Huixin, Liang, Yanwei, Lv & Chunming, Wang, 2023, Description of Bolbolaimus major sp. nov. (Nematoda), from the Yellow Sea, China and phylogenetic analysis in Microlaimidae, Zootaxa 5353 (2), pp. 176-186 : 178

Genus Bolbolaimus Cobb, 1920

Diagnosis (modified based on Leduc (2016)) Cuticle roughly annulated, sometimes ornamented with dots. Head not set off. Cephalic setae situated in same circle as outer labial sensillae or in separate circle.Amphideal fovea unispiral and situated <1 corresponding body diameter from anterior extremity, partially or completely surrounded by cuticle annulations. Buccal cavity cuticularised, with dorsal tooth and two smaller subventral teeth. Pharynx with anterior bulb and well-developed posterior bulb. Spicules short, arcuate, gubernaculum with dorsally or dorso–caudally apophysis.

Remarks: The difference between Microlaimus and Bolbolaimus has been confused for a long time. Leduc (2016) suggested absence of constriction setting off the head from the rest of the body in Bolbolaimus as a differentiating character. Among Bolbolaimus species, B. chitwoodi ( Gerlach, 1950) Jensen, 1978 , B. wieseri ( Hopper, 1961) Jensen, 1978 and B. major sp. nov. the head is slightly set off and they have prominent anterior pharynx bulb, while in B. brevis Gagarin & Nguyen Vu Thanh, 2019 , B. obesus Phan Ke Long, Gagarin, Nguyen Dinh Tu, Nguyen Thi Xuan Phuong & Nguyen Vu Thanh, 2017 and B. parvus Gagarin & Nguyen Vu Thanh, 2019 the head is not set off and they do not present anterior pharynx bulb. Differential diagnosis between Microlaimus and Bolbolaimus might be based on head and pharynx shapes, species with head not set off or/and presence of anterior pharynx bulb, and head slightly set off and with prominent anterior pharynx bulb should be kept in Bolbolaimus .