Dr David Williams

David Williams
  • Researcher, Diatoms
  • Life Sciences department
  • Genomics and Microbial Biodiversity Division
Natural History Museum
Cromwell Road



Diatom Researcher


Bachelor of Science (BSc), Biochemistry (Hons.)

Master of Science (MSc), Modern Taxonomy

Dissertation: A morphological investigation of several freshwater genera of araphid disatoms (Bacillariophyta: Fragilariales) with special reference to the girdle band structure.

Doctor of Philosophy (PhD)

Dissertation: Revision of araphid diatom genera (Bacillariophyta) closely related to the genus Fragilariforma

Professional Roles

Editorial Boards

2008--Present     Biogeography & Systematics, Editor

1992--Present     European Journal of Phycology, Editorial board (microalgal systematics)

2003--Present     Systematics and Biodiversity, Editorial Board

2009--Present    University of California Press, Species & Systematics Book Series, Editorial Board

Membership of Professional Societies

British Phycological Society; International Willi Hennig Society; International Society for Diatom Research; International Society for the History Philosophy and Social Studies of Science; The Linnean Society; Society for Systematic Biology; Systematics Association


Research Programme

My research focuses on three specific areas:

(1)  The phylogenetic relationships of diatoms;

(2)  Exploration of diatom distribution with respect to the Pacific Ocean;

(3)  Systematic theory, with special reference to developing greater understanding of the concept of homology for systematic and biogeographical studies across the natural science disciplines.

Its specific aims are fourfold:

(1)  To determine interrelationships among ‘araphid’ diatom lineages;

(2)  To present a new monophyletic classification for diatoms;

(3)  To investigate the origin of the major non-pennate clades (sessile diatoms) and determine their relationships to the pennate diatoms (motile diatoms);

(4)  To develop a greater understanding of homology in determining both taxon (organism) and spatial relationships.

My general interests are to further the study of homology: refine the concept, develop the view that homology is not simply the study of similarity but one of determining relationships, a concept applicable to morphology, development, molecules and geographical areas alike. In short, homology is the cornerstone of comparative biology.



Ebach, M.C. & Williams, DM. In prep. Cladistics (3rd edition of Cladistics: A Practical Manual). Cambridge University Press, Cambridge.

Sims, P.A. & Williams, DM. In prep. A Handbook of Cretaceous Fossil Diatoms. Cambridge University Press, Cambridge.

Williams, DM & Ebach, MC. 2007. The Foundations of Systematics & Biogeography. Springer [Preface by Professor Gareth Nelson]

Williams, DM. & Forey, PL., (eds) 2004. Milestones in Systematics. London, Taylor & Francis.

Williams, DM & Huxley, R. (eds). 1998. Christian Gottfried Ehrenberg (1795-1876): The man and his legacy. Linnean Society Special Publications no. 1, London.

Kitching, IJ., Forey, P., Humphries, CJ. & Williams, DM. 1998. Cladistics: The Theory and Practice of Parsimony Analysis. Oxford University Press, Oxford (2nd edition of Cladistics: A Practical Manual).

Scotland, RW., Siebert, DJ. & Williams, DM. (eds) 1994. Models in Phylogeny Reconstruction. Systematics Association Special Volume 52, Clarendon Press, Oxford.

Forey, P., Humphries, CJ. Kitching, IJ., Scotland, RW., Siebert, DJ. & Williams, DM. 1992. Cladistics: A Practical Manual. Oxford University Press (paperback published 1993; Korean translation published in 1998).

Refereed papers


Williams, DM. 2009. The identity of Tetracyclus constrictus (Bacillariophyceae) and a description of Tetracyclus bradburyii, a new Miocene species. Annales de Paléontologie 95: 37—51. doi:10.1016/j.annpal.2008.12.003

Williams, DM. 2009. [Letter to Linnaeus] In: Systema naturae: Letters to Linnaeus (Knapp, S. & Wheeler, Q.D., eds). Linnean Society.

Toyoda, K., Tanaka, J.  & Williams, DM. 2009. A new brackish water diatom, Achnanthes secretitaeniata sp. nov. from Japan. Journal of Japanese Botany 84: 19—26.

Stachura-Suchoples, K., Williams, DM. and Jahn, R. 2009. On extinct, freshwater taxa in the genus Thalassiosira with observations on Thalassiosira species from Pliocene deposit in Oregon, U.S.A. Diatomededelingen 33: 111-113.

Karthick B., Toyoda, K., Ramachandra, TV., & Williams, DM. 2009. A note on the identity of Ceratoneis iyengarii Gonzalves & Gandhi (Fragilariophyceae, Bacillariophyta). Diatom Research 24: 233—236.

Williams, DM. & Reid, G. 2009. New Species in the Genus Colliculoamphora Williams & Reid with Commentary on Species Concepts in Diatom Taxonomy. Beihefte zur Nova Hedwigia (Eugene Stoermer Festschrift) 135: 185—200.

Williams, DM. & Ebach, MC. 2009. What, exactly, is cladistics? Re-writing the history of systematics and biogeography. Acta Biotheoretica 57: 249-268, doi:10.1007/s10441-008-9058-5.

Stachura-Suchoples. K, and Williams, DM. 2009. Description of Conticribra tricircularis, a new genus and species of Thalassiosirales, with a discussion on its relationship to other continuous cribra species of Thalassiosira Cleve (Bacillariophyta) and its freshwater origin. European Journal of Phycology 44: 477—486. DOI: 10.1080/09670260903225431

Toyoda, K, Williams, DM, Tanaka, J., & Nagumo, T. 2008. Nomenclatural problem[s] on [in] Conferva armillaris Müller (Bacillariophyta). Bulletin of the Nippon Dental University 37: 65—70.

Reid, G. & Williams, DM. 2008.The diatom slide collection and bibliography of the Reverend Richard Fraser Bastow (c. 1888—1 October 1960). Diatom Research 23: 117—128.

Williams, DM. 2008.New names for three fossil species in the genus Tetracyclus Ralfs from Shangu County, Inner Mongolia, P.R. China. Diatom Research 23: 249—253.

Williams, DM. 2008.Paleogeographic impact of a newly described ‘cruciform’ sub-group of Tetracyclus (Bacillariophyta, Diatomaceae) Micropaleontology 53: 1—9.

Reid, G. & Williams, DM. 2008.Some commentary on molecules and morphology, species and higher taxa in diatoms, with a note on the relationships of the genus Cistula Cleve. Proceedings of the 1st Central European Diatom Meeting 2007, Kusber, W.-H. & Jahn, R. (ed.), Botanic Garden and Botanical Museum Berlin-Dahlem, Freie Universität Berlin, pp. 135—138.

Ebach, MC M.C., Morrone, J.J. & Williams, DM. 2008.An Outline of the Foundations of Systematics and Biogeography. History and Philosophy of the Life Sciences 29:21—24.

Ebach, MC, Morrone, J.J. & Williams, DM. 2008.A new cladistics of cladists. Biology and Philosophy 23: 153—156. 10.1007/s10539-007-9069-7

Tuji, A & Williams, DM. 2008.Typification and type examination of Synedra familiaris Kütz. and related taxa. Diatom 24: 25—29.

Toyoda, K., Williams, DM., Tanaka, J. and Nagumo, T. 2008.Nomenclatural problem on Conferva armillaris Müller (Bacillariophyta). Bulletin of the Nippon Dental University 37: 65—70.

Tuji, A. & Williams, DM. 2008.Examination of type material of Fragilaria mesolepta Rabenhorst and two similar, but distinct, taxa. Diatom Research 23: 503-510.

Tuji, A. & Williams, DM. 2008.Examination of types in the Fragilaria pectinalis – capitellata species complex. Proceedings of the 19th International Diatom Symposium, (A. Witkowski, ed.), pp. 125—139. Bristol: Biopress Limited.

Williams, DM. & Reid, G. 2008.The type material of Peronia fibula: morphology, systematics and relationships. Proceedings of the 19th International Diatom Symposium, (Y. Likoshway, ed.), pp. Bristol: Biopress Limited.

Williams, DM. & Ebach, MC. 2007. Heterology – The Shadows of a Shade. Cladistics 23:84—89. 10.1111/j.1096-0031.2006.00135.x

Williams, DM. 2007. Jean Louis Rodolphe Agassiz (1807—1873). In:- Great Natural Historians (ed. R. Huxley), Thames & Hudson, Natural History Museum, pp. 261—266.

Williams, DM. 2007. Richard Owen (1804—1892). In:- Great Natural Historians (ed. R. Huxley), Thames & Hudson, Natural History Museum, pp. 255—260.

Valdecasas, AG., Williams, DM., & Wheeler, QD. 2007. ‘Integrative taxonomy’ then and now: a response to Dayrat (2005). Biological Journal of the Linnean Society 93:211—216. 10.1111/j.1095-8312.2007.00919.x

Ebach, MC., Williams, DM. & Morrone, J.J. 2007. Getting Rid of Origins. Rivista Biologia 99:500—505.

Williams, D.M. 2007. Whatever Happened To Cladistics? The Systematist 28: 19—21.

Ebach, MC. & Williams, DM. 2007. Perspectives: Zangerl and the Zeitgeist. History and Philosophy of the Life Sciences 28:51—54.

Toyoda, K. & Williams, DM. 2007. Diatom types and herbaria. Aquabiology 169: 124—128 [In Japanese]

Williams, DM. 2007. Classification and diatom systematics: The past, the present and the future. In: Unravelling the Algae (eds Brodie, J. & Lewis, J.), CRC Press, pp. 57—91.

Williams, DM & Kociolek, JP. 2007. Pursuit of a natural classification of diatoms: History, monophyly and the rejection of paraphyletic taxa. European Journal of Phycology 42:313—319. DOI: 10.1080/09670260701419921

Williams, DM. 2007. Diatom phylogeny: Fossils, molecules and the extinction of evidence. Compte Rendu Palevol 6: 505–514. doi:10.1016/j.crpv.2007.09.016

Tuji, A. & Williams, DM. 2007. Type Examination of Japanese Diatoms Described by Friedrich Meister (1913) from Lake Suwa. Bulletin of the National Science Museum, series B (Botany) 33: 69—79.

Tanimura, Y., Tsuji, A., Sakai, T., Aita, Y., Suzuki, N., Ogane, K., Young, J., Williams, DM., Lazarus, D., Breidbach, O. and Bach, T. 2006. Joint Haeckel and Ehrenberg Project – A taxonomic re-examination of the Haeckel and Ehrenberg microfossil collections as a historical and scientific legacy. Research Report of the Museum Director General’s Support Program in 2004 -2006, The National Science Museum, Tokyo, p. 1—24.

Williams, DM & Reid, G. 2006. Fossils and the Tropics, the Eunotiaceae (Bacillariophyta) Expanded: The Upper Eocene fossil diatom Eunotia reedi and the Recent marine diatom Amphora reichardtiana from the Tropics. European Journal of Phycology 41: 147—154. DOI: 10.1080/09670260600628564

Tuji, A & Williams, DM. 2006. The taxonomy and distribution of Denticula kuetzingii Grunow, observed in Izu Peninsula, Japan. Memoirs of the National Science Museum 42: 7—14.

Toyoda, K., Williams, DM. Tanaka, J., Nagumo, T. 2006. Morphological investigations of the frustule, perizonium and initial valves of the freshwater species, Achnanthes crenulata Grunow (Bacillariophyceae). Phycological Research 54:173—182. 10.1111/j.1440-1835.2006.00420.x

Williams, DM. 2006. Some notes on the classification of Fragilaria, Synedra and their sub-groups. Beihefte zur Nova Hedwigia 130: 17—34.

Williams, DM., Khursevich, GK, Fedenya, SA, & Flower, RJ. 2006. The fossil record in Lake Baikal: Comments on the diversity and duration of some benthic species, with special reference to the genus Tetracyclus. Proceedings of the 18th International Diatom Symposium, BioPress Ltd., Bristol, pp. 465—478.

Tuji, A & Williams, DM. 2006. Examination of the type material of Synedra rumpens = Fragilaria rumpens Baciallriophyceae. Phycological Research 54: 99—103. DOI: 10.1111/j.1440-1835.2006.00414.x

Williams, DM. & Ebach, MC. 2006. The data matrix. Geodiversitas 28: 409—420.

Ebach, MC. & Williams, DM. 2006. Molecular systematics is not genetics. Rivista Biologia 98: 373—6.

Williams, DM. 2006. Darwin and diatoms. Science First Hand 5(10): 21. [Russian version in: Science First Hand 4(10): 39]

Williams, DM. & Reid, G. 2006. Diatom Biogeography and Water Babies: The Search for Meaning among the Protists. Diatom Research 21: 457—462.

Levkov, Z. & & Williams, DM. 2006. Two new species of Diatoma from Lakes Ohrid and Prespa, Macedonia. Diatom Research 21: 281—296.

Williams, DM. 2006. [2007] Ernst Haeckel and Louis Agassiz: Trees that Bite and their Geographical Dimension. In Ebach, MC & Tangey, R (editors), Biogeography in a Changing World. Pp, 1—59. CRC Press, Boca Raton.

Cox, EJ. & Williams, DM. 2006. Systematics of naviculoid diatoms (Bacillariophyta): A preliminary analysis of protoplast and frustule characters for family and order level classification. Systematics & Biodiversity 4: 385—399.

Toyoda, K., Tanaka, J. & Williams, DM. 2006. Morphological note on the marine diatom Achnanthes longipes C.A. Agardh from Japanese material. Diatom 22:27—33.

Tuji, A & Williams, DM. 2006. Type examination of the freshwater centric diatom Aulacoseira pusilla (F. Meister) Tuji et Houki. Diatom 22:70—73.

Ebach, MC., Williams, DM. & Morrone, J.J. 2006. Paraphyly is bad taxonomy. Taxon 55: 831—832.

Williams, DM & Reid, G. 2006. Dealing with large taxonomic groups: Diatoms species and geography. In Hodkinson TR. & Parnell JAN. (eds), Towards the Tree of Life: The Taxonomy and Systematics of Large and Species Rich Taxa. CRC Press, pp. 305—322.

Williams, DM. From Formenkreis to Progression Rule. 2006. Biogeographia 1: 3—9.

Toyoda, K., Nagumo, T., Tanaka, J. & Williams, DM. 2005. Taxonomy and fine structure of a marine diatom Achnanthes grunowii (Grunow) nom. nov. Japanese Journal of Botany 80: 1-8.

Ebach, MC, Humphries, CJ, Newman, RA, Williams, DM. & Walsh, SA. 2005. Assumption 2: opaque to intuition? Journal of Biogeography 32: 781—787.

Williams, DM. & Reid, G. 2005. The Sino-Siberian distribution of Eunotia clevei and its relatives, from Lake Baikal to the Mekon Delta: the union of taxonomy, biogeography and ecology. Memoirs of the California Academy of Sciences 56:179—187.

Williams, DM. & Reid, G. 2005. Amphorotia nov. gen., a new genus in the family Eunotiaceae (Bacillariophyceae), based on Eunotia clevei Grunow in Cleve et Grunow. Diatom Monographs, 6, 150pp, 21 pls, 5 figs.

Toyoda, K., Cox, EJ., Sims, PA., & Williams, DM. 2005. The typification of Achnanthes Bory based on Echinella stipitata Lyngbye, with an account of the morphology and fine structure of Lyngbye’s species. Diatom Research 20:375—386.

Williams, DM. & Ebach, MC. 2005. Drowning by Numbers: A new view on numerical phylogenetics. Botanical Reviews 71:355—387.

Williams, DM, Ebach, MC, Wheeler, Q. 2005. 150 reasons for paraphyly: A response. Taxon 54: 858.

Tuji, A & Williams, DM. 2005. Typification of Conferva pectinalis O.F.Müll. (Bacillariophyceae) and the identity of the type of an alleged synonym, Fragilaria capucina Desm. Taxon 55: 193—199.

Tuji, A & Williams, DM. 2005. The identity of Cyclotella glomerata Bachmann and Discostella nipponica (Skvortzov) Tuji et Williams comb. et stat. nov. (Bacillariophyceae) from Lake Kizaki, Japan. Bulletin of the National Science Museum, series B (Botany), 32: 9—14.

Tuji, A & Williams, DM. 2005. Type examination of Cyclotella wortereckii Hust. with special attention to the position of its rimoportula. Bulletin of the National Science Museum, series B (Botany) 32: 15—17.

Tuji, A. & Williams, DM. 2005. Observation of the type materials for Eunotia pectinalis (Kuetz.) Rabenh. var. pectinalis and Eunotia pectinalis var. undulata (Ralfs) Rabenh. Diatom 21: 57—60.

Williams, DM. & Humphries, CJ. 2004. Homology and character evolution. In:- T.              Stuessy, E. Hörandl and V. Mayer (eds) Deep Morphology: Toward a Renaissance of Morphology in Plant Systematics. Koeltz, Königstein, pp. 119-130.

Williams, DM. 2004. The type material of Tetracyclus japonicus (Petit) Temp. & H. Perag. and Tetracyclus eckhardii Ehrenb. (Bacillariophyceae). Cryptogamie Algologie 24:333-340.

Williams, DM. & Reid, G. 2004. Origin and diversity of the diatom genus Eunotia in Lake Baikal: Some preliminary considerations. In:- Long Continental Records From Lake Baikal, (Kashiwaya, K. ed.), pp. Kluwer Academic Publishers, pp. 259-269.

Ebach, MC., Humphries, CJ. & Williams, DM. 2004. Phylogenetic biogeography deconstructed. Journal of Biogeography 30:1285-1296.

Nelson, GJ., Williams, DM. & Ebach, MC. 2004. A Question of Conflict: Three Item and Standard Parsimony Compared. Systematics & Biodiversity 1: 145-149.

Ebach, MC. & Williams, DM. 2004. Congruence and language. Taxon 53:113-118.

Williams, DM. & Ebach, MC. 2004. The Reform of palaeontology and the rise of biogeography – 25 Years after ‘Ontogeny, Phylogeny, Paleontology and the Biogenetic law’ (Nelson 1978). Journal of Biogeography 31:685-712 [special paper, with cover illustration].

Williams, DM.  2004. On diatom endemism and biogeography: Tetracyclus and Lake Baikal Endemic Species. Proceedings of the 17th International Diatom Symposium, BioPress Ltd, pp. 433-459.

Flower, RJ., Pomazkina, G., Radionova, E., & Williams, DM. 2004. Benthic diatoms from Lake Baikal: Assessing and recording local and meso-scale patterns in species diversity. Proceedings of the 17th International Diatom Symposium, BioPress Ltd, pp. 69-92.

Forey, PL. & Williams, DM. 2004. Introduction. In Williams, DM. & Forey, PL., editors, Milestones in Systematics. London: Taylor & Francis, pp. v-viii.

Williams, DM. 2004. Homology and Homologues, Cladistics and Phenetics: 150 Years of Progress. In Williams, DM. & Forey, PL., editors, Milestones in Systematics. London: Taylor & Francis, pp. 191-224.

Ebach, MC. & Williams, DM. 2004. Classification. Taxon 53:791-794.

Williams, DM. 2004. Supertrees, Components and Three-item Data. In:- Supertrees and their uses (ed. by Olaf Bininda-Emonds). Kluwer Press, pp. 389-408.

Toyoda, K., Williams, DM. 2004. Description of Achnanthes Bory (Bacillariopheceae) based on Kützing’s type slides and materials 1: New morphological information on Achnanthes brevipes var. intermedia (Kützing) Cleve. Diatom 20: 159-65.

Williams, DM. & Metzeltin, D. 2004. A new species of Synedra Ehrenb. with comments on auxospore and initial cell morphology. Diatom 20: 57-66.

Reid, G. & Williams, DM. 2003. Systematics of the genus Gyrosigma (Bacillariophyta) including a description of three new species. Phycological Research 51:126-142.

Williams, DM. & Humphries, CJ. 2003. Component coding, three-item coding and consensus methods. Systematic Biology 52: 255-259.

Ebach, MC, Newman, RA, Humphries, CJ & Williams, DM. 2003. The Biogeographers’ Guide to 3item: Three-item Analysis for Area Cladistics. The Natural History Museum, London [Software and Manual. Updated 2005].

Williams, DM., Reid, G., Flower, R., & Votyakova, NE. 2002. A new fossil species of Tetracyclus (Bacillariophyceae) from the Miocene deposit of Tunka Ridge, Lake Baikal, Siberia, Russia. Diatom Research 17:437-443.

Reid, G. & Williams, DM. 2002. The marine diatom genus Climaconeis (Berkeleyaceae: Bacillariophyta): Two new species from Abu Dhabi, United Arab Emirate. Diatom Research 17:309-318.

Williams, DM. 2002. Precision and parsimony. Taxon 51:143-149.

Williams, DM. & Reid, G. 2002. The diatom type slides and bibliography of John Carter (1908-1993). Bulletin of the Natural History Museum (Botany) 32:137-151.

Poulin, M. &Williams, DM. 2002. Conservation of diatom biodiversity: A perspective. Proceedings of the 15th International Diatom Symposium, BioPress Ltd, pp. 161-171.

Reid, G.  & Williams, DM. 2002. On Eunotia clevei var. hispida Skvortzov from Lake Baikal. p. 89-106. Proceedings of the 16th International Diatom Symposium, University of Athens, Greece, pp. 89-106.

Kitching, IJ., Forey, PL. & Williams, DM. 2001. Cladistics. In:- Encyclopedia of Biodiversity, volume 1, A-C, Academic Press, pp. 677-692.

Williams, DM. & Reid, G. 2001. A bibliography of the botanical work of Boris V. Skvortzov (1896-1980) with commentary on the publications concerning diatoms (Bacillariophyta). Bulletin of the Natural History Museum (Botany) 31: 89-106.

Williams, DM. 2001. Comments on the structure of ‘post-auxospore’ valves of Fragilariforma virescens. Lange–Bertalot–Festschrift, Studies on diatoms (Jahn, R., Kociolek, JP., Witkowksi, A. & Compere, P., eds): 103-117.

Williams, DM & Siebert, DJ. 2000. Characters, homology and three-item statement analysis. In: Homology and Systematics (RW Scotland & T. Pennington, eds), Chapman & Hall. pp. 183-208.

Cox, EJ & Williams, DM. 2000. Systematics of naviculoid diatoms: the interrelationships of some taxa with a stauros. European Journal of Phycology 35: 273-282.

Flower, RJ. & Williams, DM. 1999. The Natural History Museum 1999 meeting on the biodiversity of Lake Baikal and a workshop on the taxonomy of Lake Baikal diatoms: A combined Report. Research Report no. 62, Environmental Change Research Centre, University of London. 26 pp.

Williams, DM & Huxley, R. 1998. Christian Gottfried Ehrenberg (1795-1876): Introduction. In: Christian Gottfried Ehrenberg (1795-1876): The man and his legacy (Williams, DM & Huxley, R, eds), Linnean Society Special Publications no. 1, pp. 1-13.

Williams, DM, Huxley, R., & Ross, R. 1998. Unravelling Ehrenberg’s names: Applying the past to the present. In: Christian Gottfried Ehrenberg (1795-1876): The man and his legacy (Williams, DM & Huxley, R, eds), Linnean Society Special Publications no. 1, 49-62.

Siebert, DJ. & Williams, DM. 1998. [1999]. Recycled. Cladistics 14: 339-347.

Karpov, SA., Kersanach, R. & Williams, DM. 1998. Ultrastructure and 18s rRNA gene sequence of a small heterotrophic flagellate Siluania monomastiga gen. et sp. nov. (Bicosecida).  European Journal of Protistology 34: 415-425.

Williams DM. 1997. Notes on the diatom species Tetracyclus castellum (Ehrenb.) Grunow with a description of Tetracyclus pseudocastellum nov. sp. Bulletin of the British Museum (Natural History), Botany 27: 1-5.

Kociolek JP, Rhode K, & Williams DM. 1997. Taxonomy, ultrastructure and biogeography of the Actinella punctata complex (Bacillariophyta: Eunotiaceae). Nova Hedwigia 65: 177-193.

Platnick, NI., Humphries CJ., Nelson, GJ. & Williams, DM. 1996. [1997]. Is Farris optimization perfect? Cladistics 12: 243-252.

Williams, DM. 1996. Notes on the genus Fragilariforma (Fragilariophyceae: Bacillariophyta) with a description of a new Miocene fossil species, Fragilariforma platensis. Beihefte zur Nova Hedwigia 112: 283-288.

Williams DM. 1996. Fossil species of the diatom genus Tetracyclus (Bacillariophyta, ‘ellipticus’ species group): Morphology, interrelationships and the relevance of ontogeny. Philosophical Transactions of the Royal Society, London, series B, 351: 1759-1782.

Williams, DM., Scotland, RW., Humphries, CJ. & Siebert, DJ. 1996. Confusion in philosophy: A comment on Williams (1992). Synthese 108: 127-136.

Williams, DM. & Embley, TM. 1996. Microbial Diversity. Annual Review of Ecology and Systematics 27: 569-595.

Williams, DM. 1996. Characters and cladograms. Taxon 45: 275-283.

Reid, G., Huxley, R. & Williams, DM. 1995.Preliminary efforts towards a diatom type catalogue with an example from Fragilariforma virescens. Proceedings of the 13th International Diatom Symposium, BioPress Ltd, pp. 423-429.

Williams, DM. 1995.Diatom Biogeography: Some preliminary considerations. Proceedings of the 13th International Diatom Symposium, BioPress Ltd, pp. 311-319.

Embley, TM., Hirt, RP. & Williams, DM. 1994. Biodiversity at the molecular level: the domains, kingdoms and phyla of life. Philosophical Transactions of the Royal Society, London B 345: 21-33.

Williams, DM. 1994. Ontogeny and phylogeny in the genus Tetracyclus. Memoirs of the California Academy of Science 17: 247-256.

Williams, DM. & Round, FE. 1994. Systematics and Science: the role of authority. Nova Hedwigia 59: 219-223.

Williams, DM. 1994. Combining trees and combining data. Taxon 43: 449-453.

Medlin, LK., Williams, DM. & Sims, PA. 1993. The evolution of the diatoms (Bacillariophyta). I. Origin of the group and assessment of the monophyly of its major divisions. European Journal of Phycology 28: 261-275.

Patterson, C., Williams, DM. & Humphries, CJ. 1993. Congruence between molecular and morphological phylogenies. Annual Review of Ecology and Systematics 24: 153-188.

Scotland, RW. & Williams, DM. 1993. Multistate characters and cladograms: When are two stamens more similar to three stamens than four? A reply to Lipscomb. Cladistics 9: 343-350.

Williams, DM. 1993. Diatom nomenclature and the future of taxonomic database studies. Beihefte zur Nova Hedwigia 106: 21-31.

Williams, DM. 1993. A note on molecular homology: Multiple patterns from single datasets. Cladistics 9: 233-245.

Williams, DM. 1993. Hustedt’s study of the diatom species Tetracyclus ellipticus: Why history is not just a chronicle of events. Hydrobiologia 269/270: 21-30.

Round, FE. & Williams, DM. 1992. The generic status of some araphid diatom genera: a reply. Nova Hedwigia 55: 485-500.

Siebert, DJ. & Williams, DM. 1992. Report on the Nucleic Acid Sequences Systematics Meeting of 23rd April, 1992. The Linnean 8: 3-7.

Williams, DM. 1992. Report for working group: Plant Taxonomic Information Systems. European Skills in Biotechnology and Genetic Resources, Exploratory meeting.

Williams, DM. 1992. Analytical techniques for systematic molecular data. Progress in Phycological Research 8: 209-249.

Williams, DM. 1992. DNA analysis Theory. In: Cladistics: A Practical Manual. Oxford University Press, pp. 89-101.

Williams, DM. 1992. DNA analysis Methods. In: Cladistics: A Practical Manual. Oxford University Press, pp. 102-123.

Navarro, Nelson R. & Williams, DM. 1991. Hyalosira tropicalis, a new tropical marine diatom. Diatom Research 6: 327-336.

Williams, DM. 1991. Phylogenetic relationships among the Chromista: A review and preliminary analysis. Cladistics 7:141-156.

Williams, DM. 1991. Cladistic methods and chromophyte phylogeny. BioSystems 25: 101-125.

Williams, DM. 1991. Fragilaria floridana Hanna: Ultrastructure of the valve and girdle and its transference to Fragilariforma Williams and Round. Ouverage dédie à Henri Germain, Koeltz, pp. 259-265.

Williams, DM., Scotland, RW. & Blackmore, S. 1990. Is there a direct ontogenetic criterion in systematics? Biological Journal of the Linnean Society 39: 99-108.

Williams, DM. & Jiaying, Li. 1990. Observations on the genus Tetracyclus Ralfs (Bacillariophyta) III. Description of two new species from Chinese fossil deposits. British phycological Journal 25: 335-338.

Williams, DM. 1990. Examination of auxospore valves in Tetracyclus from fossil specimens and the establishment of their identity. Diatom Research 5: 189-194.

Williams, DM. 1990. Distrionella D. M. Williams, nov. gen. a new araphid diatom genus closely related to Diatoma Bory. Archiv für Protistenkunde 138: 171-177.

Williams, DM. 1990. Cladistic analysis of some freshwater araphid diatoms with particular reference to Diatoma and Meridion. Plant Systematics and Evolution 171: 89-97.

Kociolek, JP., Theriot, EC. & Williams, DM. 1989. Inferring diatom phylogeny: A cladistic perspective. Diatom Research 4: 289-300.

Williams, DM. 1989. Cavitatus D. M. Williams, nov. gen.: A new genus of fossil diatom (Bacillariophyta) based on Synedra jouseana Sheshukova-Poretskaya. Review of Palaeobotany and Palynology 58: 357-362.

Williams, DM. 1989. Publication of new and revised taxa: A guide to the International Code of Botanical Nomenclatural. Journal of Palaeolimnology 2: 55-59.

Williams, DM. 1989. Observations on the genus Tetracyclus Ralfs (Bacillariophyta) II. Morphology and taxonomy of some species from the genus Stylobiblium. British phycological Journal 24: 317-327.

Williams, DM. & Round, FE. 1988. Phylogenetic Systematics of Synedra. In: Proceedings of the 9th International Diatom Symposium, Koenigstein & Biopress Ltd, Bristol, pp. 303-315.

Williams, DM. 1988. Tabulariopsis, a new genus of marine araphid diatom, with notes on the taxonomy of Tabularia Williams et Round. Nova Hedwigia 47:247-254.

Williams, DM. 1988. An illustrated catalogue of the type specimens in the Greville diatom herbarium. Bulletin of the British Museum (Natural History), Botany 18: 1-148.

Williams, DM., Hartley, B., Ross, R., Munro, MAR., Juggins, S. & Battarbee, RW. 1988. A coded check-list of British diatoms, Ensis Publishing, London, 74pp.

Williams, DM. & Round, FE. 1988. Fragilariforma, nom. nov., a new generic name for Neofragilaria Williams & Round. Diatom Research 3: 265-266.

Kociolek, JP. & Williams, DM. 1987. Unicell ontogeny and phylogeny: examples from the diatoms. Cladistics 3: 274-284.

Williams, DM. & Round, FE. 1987. Revision of the genus Fragilaria. Diatom Research 2: 267-288

Williams, DM. 1987. Observations on the genus Tetracyclus Ralfs (Bacillariophyta) I. Valve and girdle structure of the extant species. British phycological Journal 22: 383-399.

Hartley, B. [In collaboration with R. Ross & Williams, DM.]. 1986. A check-list of the freshwater brackish and marine diatoms of the British Isles and adjoining coastal waters. Journal of the Marine Biological Association, U.K. 66: 531-610.

Williams, DM. 1986. Comparative morphology of some species of Synedra with a new definition of the genus. Diatom Research 1: 131-152.

Williams, DM. 1986. Proposal to conserve the generic name Tetracyclus against Biblarium (Bacillariophyta). Taxon 35: 730-731.

Williams, DM. & Round, FE. 1986. Revision of the genus Synedra Ehrenb. Diatom Research 1: 313-339.

Williams, DM. 1985. Morphology, taxonomy and inter-relationships of the ribbed araphid diatoms from the genera Diatoma and Meridion (Diatomaceae: Bacillariophyta). Bibliotheca Diatomologica 8: 1-228. (Reviewed by DG. Mann in Phycologia, 25: 169-170, 1986 and JP. Kociolek & EC. Theriot in Phycologia, 25: 585-586, 1986).

Williams, DM. 1985. Bacillariophyta. In: DM. John & JA. Moore. Observations on the phytobenthos of the freshwater Thames. II. The floristic composition and distribution of the smaller algae using artificial surfaces. Archiv für Hydrobiologia 103: 95-96.

Williams, DM. 1982. Bacillariophyta. In: John, DM., Champ, WST & Moore, JA. The changing status of Characeae in four marl lakes in the Irish Midlands. Journal of life sciences, Royal Dublin Society 4: 67-69.