Fourteen aquatic oligochaetes were described between 1773 and 1828. Dramati
c increases in descriptions occurred in the decades beginning 1900, 1930 an
d 1960. These can be associated with specific authors, such as W. Michaelse
n and S. Hrabe. In the period 1970-1990, some 250 marine species (excluding
Enchytraeidae) were described, largely by C. Erseus. Some of the major sch
olars, such as W. Michaelsen and F. Vejdovsky, I. I. Malevic and P. G. Svet
lov, founded centers of oligochaete study that survive in Europe today. Oth
ers, such as those in the English speaking world, have had to develop in is
olation. While numerical and phenetic methods had little influence on micro
drile systematics, phylogenetic (parsimony) methods have, since the first p
ublication by B. G. M. Jamieson. Most literature prior to 1970 was taxonomi
c. Other earlier work documented community structure in relation to polluti
on. The study of Rybinsk Reservoir (Russia) stimulated a large body of ecol
ogical and biological work by T. L. Poddubnaya. The St. Lawrence Great Lake
s was also a focus for worm studies until recently. Early physiological wor
k focused on respiration, with studies dating from the 1920s. This has been
continued in relation to pollution ecology and energy flow. Physiological
work was notably absent from our first proceedings volume and only poorly r
epresented since then. Future prospects are difficult to identify. Developm
ents in ultrastructure (including sperm and muscle cells), molecular biolog
y and parsimony or cladistic phylogenetic methods will move from rather sim
ple initial work that shows the possibilities, to a revisionary phase where
the complexities begin to be revealed before it is possible to assess thei
r value. This author has too superficial a level of understanding to predic
t the outcome, but suspects that agreement among the results of several met
hods is needed for them to be persuasive. I would hope that multivariate me
thods of data analysis in pollution studies would prove superior to the dev
elopment of indices and over-reliance on toxicology. Toxicity studies are o
f use in comparing risks among products but not in predicting field effects
. Benthic biology needs a method for identifying factors that are directly
related to worm biology, such as food, rather than physical and chemical fa
ctors related to the water column. Surveys, relating communities to chemica
l and physiographic factors will remain unpredictive. It is easier to forse
e some changes in taxonomy that are almost overdue. The haplotaxids should
be broken up into several small families, Haplotaxis s.s. will be one of th
em, with a number of highly adapted and very similar species, many currentl
y regarded as synonymous, redefined by careful anatomical study. The lumbri
culids and branchiobdellidans may well be combined into a single taxon defi
ned by their unique semi-prosopore male ducts, with lumbriculids defined by
their unique muscle structure and the branchiobdellids by many apomorphic
characters related to ectocommensal life. The position of Hirudinea remains
unresolved, but relationship to this taxon is not excluded. Detailed study
of penes in lumbriculids is required. The naidids and tubificids seem to b
e a monophyly. Existing genera may be hard to analyze phylogenetically beca
use definitions are based on atrial form, which is hard to express as chara
cters. Chaetotaxy in Naididae will prove insufficient and many synonyms wil
l be declared. Capilloventridae and Randiellidae require description of mal
e ducts and gonads. They may provide evidence counter to the octogonadal th
eory of oligochaete descent, or of polyphyly in the group. Knowledge of phr
eodrilid diversity will increase.
Work will increase in Asia and South America, but sub-Saharan Africa remain
s under explored. Fish diseases will create more interest in North American
worms. New methods, including molecular studies, and renewed interest in o
ntogeny and detailed anatomical studies, may improve our ability to resolve
clusters of taxa with few, if any, apomorphic character states that remain
at the base of cladograms. An ability to include sound evidence from vesti
gial organs and logical arguments on a 'weight of evidence' basis is needed
as an adjunct. While molecular studies seem to hold much promise, early st
udies can prove over simplistic and can provide conflicting hypotheses. We
need to complete the review of taxonomy according to parsimony before major
terminology changes, such as abandonment of the term Oligochaeta, can gain
acceptance.