The Systematics, Postmarsupial Development, and Ecology of the Deep-Sea Family Neotanaidae (Crustacea: Tanaidacea) LION F. GARDINER SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 170 SERIAL PUBLICATIONS OF THE SMITHSONIAN INSTITUTION The emphasis upon publications as a means of diffusing knowledge was expressed by the first Secretary of the Smithsonian Institution. In his formal plan for the Insti- tution, Joseph Henry articulated a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge." This keynote of basic research has been adhered to over the years in the issuance of thousands of titles in serial publications under the Smithsonian imprint, com- mencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: Smithsonian Annals of Flight Smithsonian Contributions to Anthropology Smithsonian Contributions to Astrophysics Smithsonian Contributions to Botany Smithsonian Contributions to the Earth Sciences Smithsonian Contributions to Paleobiology Smithsonian Contributions to Zoology Smithsonian Studies in History and Technology In these series, the Institution publishes original articles and monographs dealing with the research and collections of its several museums and offices and of professional colleagues at other institutions of learning. These papers report newly acquired facts, synoptic interpretations of data, or original theory in specialized fields. These pub- lications are distributed by mailing lists to libraries, laboratories, and other interested institutions and specialists throughout the world. Individual copies may be obtained from the Smithsonian Institution Press as long as stocks are available. S. DILLON RIPLEY Secretary Smithsonian Institution SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 170 The Systematics, Postmarsupial Development, and Ecology of the Deep-Sea Family Neotanaidae (Crustacea: Tanaidacea) Lion F. Gardiner SMITHSONIAN INSTITUTION PRESS City of Washington 1975 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY IV Page Carololangia, new genus 167 Carololangia mirabunda, new species 168 Intraspccific Variation 175 Variations within Populations 175 Sexual Dimorphism 179 Geographic Variation 180 Variation with Depth 182 Phylogeny . 183 Development 186 Postmarsupial Development within the Neotanaidae 187 External Morphological Analysis 188 Summary of Sequence of Postmarsupial Development in Neotanais micromopher . 197 Postmarsupial Development in Herpotanais Wolff 200 Postmarsupial Development among Other Taxa 202 Patterns of Sexual Development 203 Gonadal Development 208 Histological Observations on Neotanais micromopher 209 Summary of Gonadal Structure and Function in Neotanais micromopher 217 Comparison of Gonadal Structure and Location among the Tanaidacea 219 Nomenclature and Identification of the Developmental Stages 220 The Brood Pouch Embryo 222 Miscellaneous Morphological Observations 224 Oostegites and Marsupium 224 Brood Sacs 228 Seminal Receptacles 229 The Female Gonopores 229 Structure of the Spermatozoa 230 Spinning Glands 231 Male Alimentary Modifications 232 Pleonal Fusion 232 Morphological and Developmental Abnormalities 233 Ecology 233 Food and Feeding 233 Tube-Building and Burrowing 234 Symbionts 234 Species Diversity 234 Faunal Density 237 Distribution 237 Geographic Distribution 237 Vertical Distribution 241 Insular Faunas 246 Deep-Sea and Antarctic "Gigantism" 249 Period of Reproduction 249 Summary and Conclusions 259 Literature Cited 261 The Systematics, Postmarsupial Development, and Ecology of the Deep-Sea Family Neotanaidae (Crustacea: Tanaidacea) Lion F. Gardiner Introduction ogy have dealt with postmarsupial development, and they are reviewed in detail in the develop- The major historical developments in the syste- mental section of this work. matics of the order Tanaidacea were reviewed in The most notable recent advance in the study of 1909 by Caiman (1909:190). Relatively few authors the Tanaidacea has come through the work of Karl had dealt with the biology of the group. Blanc's Lang, who, beginning in 1949, has published a long morphological study of the paratanaid Tanais and distinguished series of papers dealing with the (=Heterotanais) oerstedi (Blanc, 1884) and the order. Lang has greatly increased our understanding study by Claus (1888) on the morphology of of the Tanaidacea, primarily their systematics, and Apseudes latreillii (=A. acutifrons) were notable he is responsible for the erection of six of the eight exceptions. currently recognized families and the modification Since Caiman, most published works have been of the scope of the others. comprised of the descriptions of species or genera The present investigation began as a study of and have appeared, for the most part, in the reports the ecology of the deep-sea benthic fauna. I in- of expeditions or in local faunistic works. Collec- tended to use the Tanaidacea, one of the more tions often have been erratic, material limited, and important constituents, to represent the fauna, but various instars have been unknown from develop- it soon became apparent that systematic and devel- mental series. It frequently has been impossible to opmental problems within the order posed insur- pair dimorphic males with their females. mountable obstacles to the accomplishment of the Advancement has been slow in developing an proposed study. (These difficulties are discussed in overall systematic framework for the order and in the systematics and development sections, and the understanding tanaidacean biology. An inadequate historical development of each of these areas of understanding of complex and apparently varied research is reviewed.) Therefore, this investigation patterns of postmarsupial development has greatly has been limited to the clarification of the syste- hindered progress. In 1937 Dennell published a matic relationships within a single family, the detailed study of feeding in Apseudes. Almost all Neotanaidae, and to the elucidation of its life his- other relatively recent studies of tanaidacean biol- tory and ecology. The Neotanaidae were chosen for study because only a comparatively small number Lion F. Gardiner, Department of Zoology and Physiology, of species had been described, thus limiting the Rutgers University-The State University of New Jersey, Newark, New Jersey 07102. confusion in the taxonomic literature, and because 1 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY they are relatively large animals and more easily onomic descriptions have been written and illustra- studied than many other taxa. tions executed with nonspecialists in mind. Those The need for a complete revision of the family characters most easily used have been described Neotanaidae became obvious soon after the work to facilitate easy identification whenever possible. was begun. Many species descriptions were incom- Equipped with good descriptions, other biolo- plete and some were highly inaccurate. Relying on gists should be able to identify species of neota- these descriptions, some authors have described new naids effectively and without unreasonable effort. species without examining type specimens and have All species can be identified without resorting to unwittingly created synonyms. an examination of the mouthparts, and most spe- The collections which formed the basis of this cies with reference to relatively obvious external study were obtained from the Gay Head-Bermuda features, usually without dissection. Transect (Sanders, Hessler, and Hampson, 1965). Many problems still remain within the Neota- The Transect is a series of stations extending from naidae, and the family should serve as a fertile Gay Head on Martha's Vineyard, Massachusetts, to subject for future morphological, physiological, and Bermuda. It crosses the New England Continental ecological research. Shelf, Slope, and Rise, the Abyssal Plain of the North American Basin, and the Bermuda Rise and Slope. A wide series of environments is transected. METHODS Samples were taken from depths as shallow as 70 m COLLECTING.—Collections from the Gay Head- on the New England Shelf to over 5050 m on the Bermuda Transect were obtained with the anchor Abyssal Plain and to 1000 m on the Bermuda Slope. dredge (Sanders, Hessler, and Hampson, 1965) and All neotanaid material known to exist in mu- the epibenthic sled (Hessler and Sanders, 1967). seums was requested on loan, and all investigators These collections were made between 1960 and known to be collecting the deep-sea fauna were con- 1968 on ships of the Woods Hole Oceanographic tacted for additional specimens. These sources of Institution (WHOI), primarily on the Atlantis, material are listed below in the acknowledgments. Atlantis II, and Chain. The locations at which the animals were collected Upon arrival at the surface, samples were re- are listed in Table 1. moved from the collecting device and placed in a The rate of sampling the deep-sea environment large steel can. The animals were separated from has increased substantially during the last decade. the sediment by elutriation, using a large stream of The resulting vastly greater accumulation of mate- water running at low velocity. The water running rial has been helpful in eliminating much syste- off the surface of the sample passed through a 0.42- matic confusion within the Neotanaidae and has mm mesh sieve upon which the animals were re- been essential to the understanding