Bolbolaimus Cobb, 1920

Leduc, Daniel, 2016, One new genus and three new species of deep-sea nematodes (Nematoda: Microlaimidae) from the Southwest Pacific Ocean and Ross Sea, Zootaxa 4079 (2), pp. 255-271 : 264

Bolbolaimus Cobb, 1920

Diagnosis. (modified from Tchesunov (21014)) Cuticle 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 situated <1 corresponding body diameter (cbd) 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.

Type species. B. pellucidus Cobb, 1920

Remarks. The genus Pseudomicrolaimus Sergeeva, 1976 was synonymised with Bolbolaimus by Jensen (1978), but was later re-instated as a valid genus by Kovalyev & Tchesunov (2005) based on the presence of denticles in the buccal cavity. The latter authors list three valid Pseudomicrolaimus species: P. murinae Sergeeva, 1976 , P. dentatus (Allgén, 1935) , and P. denticulatus ( Cobb, 1920) . Kovalyev & Tchesunov (2005), however, assigned the wrong authority to the latter species, which should be P. denticulatus (Gerlach, 1953) . Bolbolaimus amabilis De Man, 1922 and B. cobbi Chitwood, 1937 were considered species inquirendae by Jensen (1978) due to incomplete descriptions. Jensen (1978) also transferred Microlaimus chitwoodi (Chitwood, 1937) , M. crassiceps Gerlach 1953 , M. teutonicus Riemann, 1966 and M. wieseri (Hopper, 1961) to Bolbolaimus based on cuticule ornamentation and heavy cuticularisation of the copulatory apparatus. Microlaimus . wieseri , however, is characterised by a set off head (a trait not found in any other Bolbolaimus species), and should be transferred back to Microlaimus . As noted by Leduc & Verschelde (2015), Chromaspirina longisetosa Jensen, 1985 was transferred to Bolbolaimus (erratum?) by Muthumbi et al. (1995), but later transferred to Bolbonema by Verschelde et al. (1998). Tchesunov (2014) noted that B. bahari Muthumbi & Vincx, 1999 and B. abebei Muthumbi & Vincx, 1999 do not possess a prominent anterior pharyngeal bulb, unlike all other species of the genus. These species, however, are also characterised by having amphideal fovea incompletely surrounded by cuticle annulations and situated far anteriorly (<1 corresponding body diameter (cbd) from anterior extremity), and their heads are not set off. These species therefore have affinities with both Bolbolaimus and Microlaimus . The generic placement of these species should be left unchanged until a revision of Bolbolaimus is conducted based on a new observations on the type species and molecular data become available.