Microlaimus De Man, 1880

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 : 257-258

Genus Microlaimus De Man, 1880

Synonyms

Microlaimoides Hoeppli, 1926 Paracothonolaimus Schulz, 1932

Diagnosis. (modified from Tchesunov (2014)) Cuticle annulated, in some species also showing punctations or longitudinal bars. Head slightly set off. Spicules usually short and arcuate, seldom long and slender; gubernaculum present, often bent distally but without dorso-caudal apophyses. Papilloid precloacal supplements may be present.

Type species. M. globiceps De Man, 1880

Remarks. Kovalyev and Tchesunov (2005) provided a list of 70 valid Microlaimus species. An updated list, which takes into account nomenclatural changes outlined above, is provided below and comprises 83 valid species. The new list includes species that were omitted by Kovalyev & Tchesunov (2005), namely M. donsi Allgén, 1935 and M. paraborealis Allgén, 1940 , and species described since the publication of the original list (including M. korari n. sp.).

Kovalyev & Tchesunov (2005) did not include M. nanus Blome, 1982 and M. nympha Bussau & Vopel, 1999 in their list of Microlaimus species based on the presence of only one testis, a trait they considered to show closer affinities with Aponema . These species, however, do not possess dorso-caudal apophyses and should therefore be transferred back to Microlaimus ( Tchesunov 2014) .

Microlaimus tenuicaudatus Allgén, 1959 and M. tenuispiculum De Man, 1922 were included in the list of Kovalyev & Tchesunov (2005), presumably by mistake, despite their transfer to Molgolaimus by Jensen (1978). Microlaimus teutonicus Riemann, 1966 was also included in the previous list despite its transfer to Bolbolaimus by Jensen (1978). These species are omitted from the new updated list.

Microlaimus wieseri (Hopper, 1961) was transferred to Bolbolaimus by Jensen (1978) 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, see below), and should be transferred back to Microlaimus until the diagnosis of Bolbolaimus is clarified.