Marine Interstitial Heterotardigrada from the Pacific Coast of the United States, including a Description of Batillipes tridentatus n. sp

Eight intertidal beach localities along the Pacific coast of the United States were surveyed: two in Washington, one in Oregon, and five in California. Seven species of marine Heterotardigrada were encountered including Stygarctus bradypus, S. spinifer, Halechiniscus remanei, Batillipes gilmartini, B. mirus, and Echiniscoides sp. A new species, B. tridentatus n. sp., from Washington and California is distinctive in possessing two pairs of lateral projections between legs III and IV, a prominent spike on the shank of legs IV, and a two-pointed caudal apparatus. Despite interest in marine Tardigrada worldwide (see Renaud-Mornant, 1982) and along the east coast of the United States (e.g., Kristensen & Higgins, 1984b; Lindgren, 1971; McGinty & Higgins, 1968; McKirdy, 1975; Pollock, 1970a,b), the west coast of North America has received little attention. Only four species, all from California, are reported from the entire coast. Echiniscoides sigismundi (Schultze, 1865) is known from Dillon Beach (Schuster & Grigarick, 1965) and from Santa Cruz Island (Schuster & Grigarick, 1970). (These animals were tentatively referred to the subspecies, E. sigismundi groenlandicus, by Kristensen & Hallas, 1980.) Styraconyx sargassi Thulin, 1942 was first reported from California by Mathews (1938, as Bathyechiniscus tetronyx) and later by Schuster & Grigarick (1965) from Dillon Beach. The genus Batillipes is represented by the description of B. gilmartini from Pacific Grove (McGinty, 1969), where it was found with Halechiniscus remanei. Finally, Meyer (personal communication) reported Batillipes mirus in the San Diego area. The specific objective of this survey was to expand our knowledge of the marine tardigrade fauna of the Pacific coast of the United States. In a larger context, added information regarding this poorly understood segment of the Pacific tardigrade fauna should contribute to future discussions of global tardigrade biogeography. MATERIALS AND METHODS During summer 1987, collections were made from selected beaches along the northeastern Pacific coast from Seattle, Washington to southern California; these included two beaches in Washington state, one from Oregon, and four from California. Collections were made in 1983 from a fifth California site. Although this study was not exhaustive, collections were made to survey the full intertidal range of each beach comparably at each locale. Publication costs, in part, are being met by a grant from the Spencer-Tolles Fund of the American Microscopical Society. TRANS. AM. MICROSC. SOC., 108(2): 169-189. 1989. ? Copyright, 1989, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.235 on Fri, 07 Oct 2016 04:56:52 UTC All use subject to http://about.jstor.org/terms TRANS. AM. MICROSC. SOC. A semi-quantitative sampling procedure was used. Sample sites were located at the low tidal line and at /4, /2, and 3/4 tidal heights along the beach. At most sites, samples were taken from the sand surface to the depth of the low tidal water table (or close thereto) at 15-cm intervals (1-15, 15-30, 30-45, 45-60 cm, etc.). Each sample consisted of approximately 250 cm3 of sediment representing equal quantities taken from each 15-cm depth interval. Each sample was soaked in approximately 3 liters of fresh water, following a procedure modified from Kristensen & Higgins (1984b). After 10 min, including periodic swirling of the bucket and its contents, sand and meiofauna (presumed to be osmotically incapacitated) were thoroughly suspended in the water medium. Heavier material, mostly sand, was allowed to settle briefly and lighter objects, including meiofauna, were decanted through a filter of 62-gm mesh. Organisms and debris retained by the net were preserved in 10% formalin, lightly tinted with rose bengal stain. During subsequent storage, preserved organisms absorbed pink coloring from the stain making them easier to discern from surrounding debris during sorting, manipulation, and identification. In the laboratory, subsamples of each resuspended sample were diluted with tap water and examined using a dissecting microscope at 40-60 x. Specimens were examined as uncovered wet mounts using an inverted phase-contrast microscope or as temporarily covered wet mounts with differential interference microscopy. The former technique has the advantage of avoiding distortion from cover glass pressure and of permitting reorientation of specimens during observation. Permanent mounts were made by adding some specimens to a 10% solution of glycerine in ethanol which was allowed to evaporate to pure glycerine. Tardigrades were mounted in glycerine on Cobb slides using a double cover glass technique. Cover glasses were sealed by Cytomount? and ringed with epoxy paint. Drawings were made using a video-camera lucida technique. Specimens were projected by video camera onto a high resolution (700-line) television monitor. A plate of one-way mirror glass was mounted at a 45? slope (low side toward the monitor) on a light table placed immediately in front of the monitor. When observed from above this sloping mirror, a clear and undistorted reflection of the televised image was observable coincident with a faint image of a drawing pencil placed on paper on the light table surface beneath. The televised image could then be traced accurately. Measurements were made from drawings using a digitizing tablet attached to a microcomputer. Granulometric surveys followed procedures of Hulings & Gray (1971). Single samples of sand representative of each beach were screened and weighed. The graphic mean and sorting were calculated. Dried, weighed samples were repeatedly flooded with excess 10% HC1 until no further reaction was observed and then redried to calculate the percentage calcium carbonate in samples. Collection sites. Pertinent data regarding study sites are summarized in Table I. Granulometric analyses for five of these sites are shown in Fig. 1. Site 1: Golden Gardens Park, Meadow Point, on Shilshole Bay, Puget Sound north of Seattle, Washington. This beach includes a wide assortment of grain sizes, including gravel and cobble components. Collection was limited to me170 This content downloaded from 157.55.39.235 on Fri, 07 Oct 2016 04:56:52 UTC All use subject to http://about.jstor.org/terms VOL. 108, NO. 2, APRIL 1989