A new roundworm: Aegialoalaimus bratteni

The roundworms or nematods are inhabiting nearly every habitat of our planet. Nematode species are difficult to distinguish as they are morphologically very uniform, and although over 25,000 have been described, of which more than half are parasitic, the total number of nematode species has been estimated to be about 1 million (or more).

Nathan Cobb, one of the world's leader of nematode science once said about the ubiquity of nematodes on Earth: In short, if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of the various plants and animals would still be decipherable, and, had we sufficient knowledge, in many cases even their species could be determined by an examination of their erstwhile nematode parasites.

This new find comes from bottom sediment samples that were collected in several locations in the southern part of the Skagerrak called Bratten area hence the species name Aegialoalaimus bratteni.

For the experts: New species, Aegialoalaimus bratteni sp. n. was found in Skagerrak off the west coast of Sweden. It is particularly characterized by the 1.5-1.8 mm long body, short papilliform cephalic sensilla, excretory pore opening just posterior to nerve ring level, spicules that are straight in shape, supplements and gubernaculum absent, separating it from other valid species of the genus. It can be further differentiated from Aegialoalaimus elegans in having longer body (1.5-1.8 mm in A. bratteni sp. n. vs 0.8-1.3 mm in A. elegans), shape and size of spicules (straight and 22-29 µm long in A. bratteni sp. n. vs arcuate and 34 µm long in A. elegans), absence of precloacal supplements (vs seven-eight in A. elegans), absence of gubernaculum (vs present in A. elegans); from A. setosa in having shorter tail (c´=2.6-3.1 in A. bratteni sp. n. vs c´=4.2 in A. setosa), shorter cephalic sensilla (0.5-1.0 µm in A. bratteni sp. n. vs 9 µm in A. setosa), shape and size of spicules (straight and 22-29 µm long in A. bratteni sp. n. vs arcuate and 40-45 µm long in A. setosa), absence of precloacal supplements (vs eight in A. setosa), absence of gubernaculum (vs present in A. setosa); from A. leptosoma in having longer body (1.5-1.8 mm in A. bratteni sp. n. vs 0.5-0.7 mm in A. leptosoma) and other measurements, shape of spicules (straight in A. bratteni sp. n. vs arcuate in A. leptosoma), absence of precloacal supplements (vs three-five in A. leptosoma), absence of gubernaculum (vs present in A. leptosoma). Type specimens of Aegialoalaimus cylindricauda Allgén, 1933 and A. paratenuicaudatus Allgén, 1959 are redescribed and taxonomic status of these two species is re-evaluated. A taxonomic review, tabular compendium and identification key for species of the genus Aegialoalaimus are also given.