Hall of Fame - Arthur Humes (4)

The Lichomolgoid Complex

Over his long career Humes exhibited a particular affinity for one family-group above all others, the Lichomolgidae. The enormous numbers of new species and genera added to this family-group by Humes and his collaborators over the years stimulated two major revisionary works. The first revision was published in 1973 in collaboration with Jan Stock (Humes and Stock, 1973), although the new genera and families were validly published a year earlier (Humes and Stock, 1972). In this work three new families, Pseudanthessiidae, Rhynchomolgidae and Urocopiidae, were established and placed in a new superfamily, the Lichomolgoidea, together with the two existing families, the Lichomolgidae and Sabelliphilidae. These families were distinguished largely on the basis of differences in the segmentation and setation of the first to fifth swimming legs. However, by the mid 1990s more than 40 new genera had been added to the lichomolgoid complex and the boundaries between the five constituent families had become blurred. Humes and Boxshall (1996) undertook a further revision of the lichomolgoid complex, excluding the Urocopiidae, and recognized six new families, the Anchimolgidae, Kelleriidae, Octopicolidae, Macrochironidae, Synapticolidae and Thamnomolgidae. Together with his numerous co-authors, Humes' cumulative contribution to the expansion of knowledge of the lichomolgoid complex is a total of eight new families (excluding the Urocopiidae), 90 new genera and an amazing 385 new species. These absolute numbers represent 80% of the known families, 67% of the genera and 68% of the species, respectively.

The Mollusc Parasites

During the 1950s Arthur almost exclusively wrote on copepods associated with molluscs and echinoderms. It was during this period that his first disciple, Roger Cressey, entered his laboratory and jointly worked up the material collected from West African bivalves (Humes and Cressey, 1958a). Meanwhile, Arthur concentrated also on the mollusc associates from Madagascar which resulted in a major contribution the following year (Humes, 1959). Over his career Humes returned many times to the study of parasites of marine molluscs, paying particular attention to the heterogeneous family, the Myicolidae, established without diagnosis by Yamaguti (1936). In 1986 Humes restricted the concept of the family by excluding five genera which he placed in a newly designated family, the Anthessiidae. Humes (1986a) retained only the genera Myicola, Pseudomyicola and Ostrincola in the Myicolidae and provided detailed diagnoses of both families. Later Humes and Boxshall (1988) added Parostrincola, unique within the family in its utilization of an intertidal brachiopod, Lingula anatina Lamarck, as host and Ho and Kim (1992) established two further new genera, one of which, Exostrincola, was based on Ostrincola simplex Humes, 1958. The myicolids are typically parasites of marine bivalve molluscs, occurring on the gills, in the mantle cavity and in the intestine of their hosts. Describing these taxa and creating a more robust classification system represents a real contribution to societal needs. Some myicolids are serious pests of commercially cultured bivalves and have been responsible for mass mortality in cultured bivalves (Ho and Zheng, 1994; Ho and Yoosukh, 1994). As the economic importance of aquaculture increases world wide, the basic descriptive taxonomy of these potential pests generated by Humes will provide the platform on which subsequent life cycle and biological research can be built.

Echinoderm Associates - A Lasting Affiliation

All five classes of echinoderms serve as hosts for copepods and Arthur made major contributions across all five, totalling 137 new species. He published his first paper on the group in 1958 and continued working on echinoderm associates throughout his career until his death. In fact, one of his very last papers dealt with the biology and taxonomy of species of Ophiopsyllus Stock, Humes & Gooding, 1963 and Pseudanthessius Claus, 1889 associated with ophiuroids in Belize (Humes & Hendler, 1999).

Arthur's research on echinoderm associates serves to demonstrate the sheer abundance of copepods associated with marine invertebrate hosts. Despite his own attempt to estimate the number of copepods (Humes, 1994), their absolute abundance appears to be beyond imagination and certainly beyond calculation. One classic example of the tremendous carrying capacity of these hosts is demonstrated in his first paper dealing with the large tropical basket star Astroboa nuda (Lyman) (Humes, 1973b). From three basket stars (approximately 20 cm in diameter) examined, Arthur recovered a staggering 27,209 individuals of Collocherides astroboae Stock, 1971 and Doridicola micropus (Humes, 1973). Another example is the siphonostomatoid family Stellicomitidae, the first new family recognized by Humes (Humes and Cressey, 1958b). These tiny associated copepods inhabit starfishes and can reach enormous population densities on their hosts. Humes (1971), for example, reported 1420 individuals of Stellicomes supplicans Humes, 1971 on just two individual starfishes only 10 cm in diameter.

In addition to describing four new families associated with echinoderms (Humes, 1974; Humes and Boxshall, 1996; Humes and Cressey, 1958b, 1959), Arthur also contributed significantly to our knowledge of the Taeniacanthidae. This is a very unusual family in that it utilizes both invertebrates and vertebrates as hosts. The 91 species and 14 genera of taeniacanthids recognized as valid by Dojiri and Cressey (1987) fall into two ecological groups according to host preference. Three genera, Echinosocius Humes and Cressey, 1961, Echinirus Humes and Cressey, 1961 and Clavisodalis Humes, 1970 are associates of sea urchins (Echinoidea). These three genera comprise a total of 14 species which occur only in the Indo-west Pacific and Red Sea and inhabit the oesophagus of their echinoderm hosts. Arthur was author or co-author of 12 of these 14 known species. The remaining 11 genera are widely distributed parasites of marine fishes, both elasmobranchs and teleosts. This family has been extensively studied and was the subject of two revisions. Dojiri and Humes (1982) reviewed the taeniacanthids parasitic on sea urchins in the southwestern Pacific and provided a key to the known species of urchin parasites worldwide. Dojiri and Cressey (1987) revised the entire family and provided a comprehensive diagnosis of the family, a key to genera and keys to the species parasitic on fishes.

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