Hall of Fame - Arthur Humes (5)

Hydrothermal Vents, Cold Seeps and the Dirivultid Explosion

The discovery of a specialized fauna associated with the larger invertebrates living at hydrothermal vents and cold seeps, provided Arthur Humes with a new challenge in the early 1980s. The family Dirivultidae was established in 1981 (Humes and Dojiri, 1981) based on a single species of a new genus, Dirivultus Humes and Dojiri, 1981, collected from a vestimentiferan worm off the California coast. Because of different in press times, in the preceding year (1980) these authors added a second monotypic genus, Ceuthoecetes Humes and Dojiri, 1980, also associated with a vestimentiferan host. During two decades Arthur served as the main recipient for new copepod collections from hydrothermal vents and cold seeps worldwide which enabled him to publish extensively on the subject, including no less than 15 papers dealing with the Dirivultidae. Due to his single-handed efforts this family has now grown to comprise twelve genera and 53 species, if we include Fissuricola Humes, 1987, which was not originally placed in this family by Humes (1987). The dirivultids are the dominant group of copepods at most hydrothermal sites in the eastern Pacific, in the Marianas Back-Arc Basin and on the mid-Atlantic ridge and, given that Tunnicliffe et al. (1998) listed 443 hydrothermal vent species, dirivultids constitute over 10 percent of the faunal diversity at hydrothermal sites. They have been found in the washings of tubicolous polychaetes, gastropods, bivalves, and in the gill chambers and around the oral region of shrimps and crabs, as well as attached to the tentacular crown of vestimentiferan worms. Dirivultidae can be hyperabundant at vent sites as illustrated by Humes (1990b) who found over 15,000 individuals of Stygiopontius quadrispinosus Humes, 1987 in 210 ml of flocculent material collected from at the Gorda Ridge in the Eastern Pacific. Of particular significance was Arthur's discovery of eight pairs in amplexus of this species which subsequently provided the first information on the functional morphology of the digeniculate antennules and their role in precopulatory mate guarding in siphonostomatoid copepods (Huys and Boxshall, 1991).

A second family of siphonostomatoid copepods, the Ecbathyriontidae, was established by Humes in 1987, based on a single new species found in the deep-sea hydrothermal vent fauna on the Galapagos Rift. This family remains monotypic and its host group is unknown. It is of particular phylogenetic interest in that, in addition to the large aesthetasc derived from ancestral antennulary segment XXI, the male of Ecbathyrion prolixicuada Humes, 1987 retains an exceptionally high number of aesthetascs, those derived from ancestral segments I to IV, VII, IX to XI, XIV, XVI, and XVIII (Huys and Boxshall, 1991).

Another hydrothermal vent family established by Humes, the Erebonasteridae, is the only family of the order Poecilostomatoida in which ventral copulatory pores are found that are separate from the genital apertures on the dorsal surface of the female genital double-somite. It is also the only family in the order to retain a discrete mandibular palp (Humes, 1987). The family is characterized by these two extreme plesiomorphic states and this family, together with another family - the Fratiidae (cf. Ho et al., 1998) - of invertebrate associates, will be of pivotal importance in the emerging concept of the Cyclopoida and Poecilostomatoida as a monophyletic taxon.

His Legacy

In this short appreciation we cannot do justice to the breadth and depth of Arthur Humes' contributions to copepod taxonomy. We have attempted to pick out a few highlights that seem, to us, to be of particular significance. We wish to stress that the accuracy and detail of Arthur Humes' taxonomic descriptions and those of his students, Roger Cressey, Richard Gooding, Ju-shey Ho and Masahiro Dojiri, are exemplary. He set a consistently high standard in his illustrations, which ensured he was providing data that would be of lasting value in biodiversity studies and phylogenetic analyses long into the future. His students continued this tradition and Arthur's far-reaching influence will be of benefit to copepodology far into the 21st Century.

Arthur was a born systematist who loved to synthesize information. His synoptic treatments made it possible to become familiar with the wide diversity of copepods associated with particular host groups such as the Holothuroidea (Humes, 1980), Actiniaria (Humes, 1982a), Asteroidea (Humes, 1986b) and Alcyonacea (Humes, 1990a), and to identify them without having to possess the scattered original literature. Arthur always went to great effort to identify the host in order to promote studies on host specificity and geographical distribution. He believed that knowledge of the exact host name could potentially shortcut the identification process significantly and therefore he regularly updated records on host-copepod associations in a synthetic cross-referenced format.

From the start of his career Humes recognized that name-bearing types are the sole international standards of reference and should be deposited in an institution that maintains a research collection with proper facilities for preserving them and making them available for study to others. More than just being a tireless collector, Arthur deposited type material of each of the 700+ species he described in international museums such as the National Museum of Natural History in Washington, the Natural History Museum in London, the Rijksmuseum van Natuurlijke Historie in Leiden, the Zoologisch Museum in Amsterdam and the Musée National d'Histoire Naturelle in Paris. His collections frequently comprised hundreds of paratypes of which he would normally deposit the vast majority in a major museum and the remainder in his own wonderfully arranged reference collection. In addition, he deposited material of numerous other species, previously described by others but rediscovered during his own fieldwork. His meticulously curated personal collection was bequeathed to the National Museum of Natural History and together with his earlier donations constitutes the largest copepod collection accumulated ever during an individual's lifetime. The new fourth edition of the International Code of Zoological Nomenclature has introduced a mandatory requirement for the availability of new species-group taxa published after 1999, i.e. a statement naming the collection in which the type is or will be deposited (Art. 16.4.2). As with his methods Humes was well ahead of his time and ensured a lasting legacy.

Arthur undoubtedly left many works unfinished. The fact that interest in the siphonostomatoids did not equal interest in the poecilostomatoids is largely due to Arthur's influence and contribution. On several occasions he referred to the many collections of siphonostomatoid copepods, acquired during his nearly four years of fieldwork in the 1960s and 1970s, and still awaiting study in his lab. Similarly, he felt that his collections of copepods associated with ascidian hosts had not yet received the attention they deserved. During the Fifth International Copepod Conference in Baltimore in 1993, the last of its kind he attended, Arthur voiced his intention to continue describing copepods until the turn of the millennium. In view of Arthur's sustained output in recent years, which showed no sign of decline, and the prospect of more research time following his retirement as Editor of Journal of Crustacean Biology, it is unlikely that this turning point would have marked the end of his extraordinarily productive career.

In recognition of his monumental work on copepod systematics Arthur Humes was a recipient of the Research Excellence Award given by The Crustacean Society. Uniquely, the Board of The Crustacean Society voted to bestow this honour on Arthur Humes posthumously, since the nomination process had been completed before his death. At the winter meeting of The Crustacean Society in Atlanta in January 2000, the award was presented by the President, Dr Joel Martin, to Dr Charles Derby who accepted it on behalf of Arthur Humes. This award has since been renamed the Arthur G Humes Award for Excellence in Research. Finally, a commemorative issue of Journal of Crustacean Biology (vol. 21(1): ii + 316 pp.) dedicated to Arthur was published in February 2001. It includes an obituary by Ju-shey Ho and contributions by no less than 35 fellow carcinologists.

It is difficult to imagine the field of associated copepods without Arthur Humes. In these times of decreasing support for, and interest in, taxonomic research, the shear volume of his work may never be surpassed. To paraphrase the title of his own past-presidential address presented at the Annual Meeting of the American Microscopical Society in Denver in December 1984 (Humes, 1985b), any biographical sketch of the man, who never lost his fascination with his beloved animals, could simply be condensed as "Arthur Humes and Copepods: A Success Story".

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