A redescription of types of the clam shrimp Eulimnadia agassizii (Spinicaudata : Limnadiidae)

Abstract

Among the described North American species of the clam shrimp family Limnadiidae, Eulimnadia agassizii is poorly known, having been reported from only two localities in extreme southeastern New England. Though recently reported as nonexistent, the original specimens of this species are in the type collection of the Museum of Comparative Zoology, Harvard University. Specific data regarding the collection and an emended and expanded description of the type material are provided, using traditional and contemporary characters, to complement recent studies of the group. In a revision of the Recent Limnadiidae of North America, Belk (1989) discussed traditional characters used to diagnose species and suggested that egg shell morphology demonstrates less intraspecific variation, thus allowing more confident separation of species. Among the several named forms included in his review was Eulimnadia agassizii, a poorly known species from southeastern New England. E. agassizii was described (as Limnadia) from Penikese Island in what is now the town of Gosnold, Barnstable County, Massachusetts, by Packard (1874a). Along with a stone plaque and a few obscured foundations, the description of E. agassizii is all that remains of an early attempt to establish a marine biology laboratory on the island (later permanently founded at nearby Woods Hole, Massachusetts). Packard (1883) eventually included E. agassizii in his genus Eulimnadia, first formally proposed as a subgenus (Packard, 1847b). Eulimnadia has been recognized by most subsequent authors, although Webb & Bell (1979) reviewed earlier data that suggested overlap in the two taxa and recommended that Eulimnadia be synonymized with Limnadia. Additional study is needed to resolve the two views. Belk (1989) remarked that Packard did not "leave any type material." In fact, the specimens collected by Walter Faxon on Penikese Island, and certainly the same or part of the same collection used by Packard, exists in the Museum of Comparative Zoology, Harvard University, at Cambridge, Massachusetts. The specimens are labeled as "types" and are in the type collection but have not been cataloged. No specific holotype was designated. Unaware of the collection, Belk (1989) used specimens of E. agassizii collected in Woods Hole, Massachusetts, to characterize E. agassizii. Though the Woods Hole collection is useful for purposes of comparison with other species, it nevertheless would be useful to provide an accurate redescription of the type collection. Using type material, I redescribe the species below. Variations in certain characters 11 thank Ellie Armstrong-Prosser of the Grey Museum for kindly loaning their collection of Eulimnadia agassizii for study. Dr. Denton Belk provided comments on different drafts of the manuscript. TRANS. AM. MICROSC. Soc., 111(3): 223-228. 1992. ? Copyright, 1992, by the American Microscopical Society, Inc. This content downloaded from 207.46.13.11 on Wed, 19 Oct 2016 04:41:46 UTC All use subject to http://about.jstor.org/terms TRANS. AM. MICROSC. SOC. discussed by Packard (1874a,b, 1883) are noted. Egg shell and telson morphology are redescribed based on scanning electron microscopy. MATERIALS AND METHODS The series of specimens examined are distributed among two lots, each designated as part of the type collection. Neither lot is cataloged. The only written record in the collection concerning the specimens is a statement in an accession log dated September 1873, indicating that W. Faxon donated a series of specimens from Penikese Island, Buzzards Bay, Massachusetts. Both lots are preserved in 70% ethanol. The first lot is labeled "pool on Penikese Island, Buzzards Bay Mass 27 Aug. 1873 coll. by Walter Faxon." A second label states "Eulimnadia agassizii Packard Type!." The lot contains 196 specimens, all females. The second lot is marked "Eulimnadia agassizii Type! Penikese Island, Buzzards Bay Aug. 27 1873 W. Faxon." There are six female specimens in the lot. Fourteen specimens were removed from the large lot and used to furnish body parts for light and scanning electron microscopical (SEM) investigations. Body parts used for light microscopy were cleared and mounted in Hoyer's medium, a semipermanent mounting medium. For SEM examination, eggs and entire telsons were dehydrated, coated, and examined with a JEOL model JSM 3500 scanning electron microscope. The drawings of the head are free-hand renditions of slide mounts using an ocular grid to determine key point dimensions. All prepared material, including slides and SEM stubs, was returned to the type collection in the Museum of Comparative Zoology, Harvard University. In addition, specimens of E. agassizii maintained in the collections of the Marine Biological Laboratory (Grey Museum 994), Woods Hole, Massachusetts, collected 9 August 1970 by D. J. Zinn were examined. Nine female specimens are in the collection. Examinations of these latter specimens were limited to use of light microscopy.