NOTES AND NEWS OCCURRENCE OF THE AMPHIPOD LEUCOTHOIDES POTTSI SHOEMAKER IN THE TUNICATE ECTEINASCIDIA TURBINATA HERDMAN FROM BIG PINE KEY, FLORIDA, U.S.A. BY JAMES DARWIN THOMAS Newfound Harbor Marine Institute, Big Pine Key, Fla. 33043, U.S.A. Specimens of Leucothoide.r pott.ri Shoemaker, 1933 are routinely taken from the tunicate Ecteina.rcidia turbiiiata Herdman, 1880 in the shallow waters at the south- western tip of Big Pine Key, Florida. Observations of the aanphipod within the tunicate show Leucothoide.r pottsi to be an inquiline feeding on food particles brought in by water currents created by the tunicate. E. turbinata is locally abundant and one of the most common ascidians in the West Indian Region (Van Name, 1945). The colony in this species consists of clusters of individuals connected at their base by stolons which also attach the colony to the substrate. Zooids in life are bright orange, and individual zooids reach a maximum size of 20 mm. Most of the amphipods were found in zooids larger than 15 mm. E. turbinata is common in harbors and shallow waters of the Florida Keys, but amphipods were found only in tunicates taken in or around shallow sponge and patch reef communities (1-2 m). Although it has been assumed that species of Leucothoide.r inhabit sponge and ascidian hosts, no specific host-commensal relationships have been documented. Specimens were collected by hand while snorkeling. The transparent nature of the test allows rapid evaluation for the presence of amphipods. Clumps of E. tur- binata were found attached to various substrates. Tunicates found to contain amphipods were put in jars with seawater and transported to the lab for obser- vation. Several clusters of tunicates containing amphipods were taken from the exterior of sponges. Subsequent dissection of these sponges revealed other com- mensal amphipods; Leucothoe .rpi?ztcdYpa (Abildgaard, 1789), Anamixis han.reni Stebbing, 1897, and Colonaa.rtix janicae Heard & Perlmutter, 1977, but no speci- mens of L. pott.ri. L. pott.ri was observed for approximately 40 hours to determine its activities within the tunicate. Several tunicates containing amphipods were placed in a dish of seawater for viewing under the microscope. Two types of behavior were noted for L. pott.ri; a very active random wandering pattern, and a resting state within the tunicate. The wandering activity was usually exhibited after the specimens 108 had been disturbed in some manner. Random wandering began on the exterior of the tunicate in a criss-cross manner. Upon encountering one of the atrial openings (usually the incurrent opening), the amphipod would enter the branchial sac and proceed to the base. The amphipod then returned to the incurrent opening, probed the branchial tentacles and exited to repeat the pattern. One specimen of L. pott.ri was observed in this mode for almost an hour. Amphipods usually remain on or in one specific tunicate rather than wandering from one to another even though the tunicates may be in close proximity or touching. The resting state was the most common pattern of behavior when the tunicates had been undisturbed. Amphipods resting in the branchial sac had reduced pleopodal activity, apparently utilizing the current created by the tunicate as an aid in respiration. Occasionally, L. pottsi was found just inside the excurrent opening between the test and the branchial sac. Feeding, when observed, was filter feeding rather than the active pursuit and handling of food material. At no time was L. pott.ri observed feeding on the host tissue. While feeding, antennae 1 and 2 were drawn ventrally to be scraped by the maxillipeds and gnathopods 1 and 2. Gnathopod 2 was used to clean pereopods 3 to 7 and the urosome by drawing the second gnathopod across these structures. Gnathopod 2 and pereopod 7 were also flexed outward and used to clean the out- side surface of the exoskeleton. Ingested food particles were minute, and gut particle composition from L. pottsi was not recognizable under high magnification (600 X ) . The mandible of L. pottsi lacks a molar and bears a short, one-seg- mented palp. This suggests the species seeks a food source that requires little processing. A peculiar activity for which I could find no obvious function was the constant snapping or flexing of the dactyl of gnathopod 1. This snapping behavior took place almost constantly and could be a sound-producing mechanism or sensory in nature. Ratio of males to females was 1:1 and ovigerous females were frequently seen carrying 10 to 15 eggs of a deep green color. Leucothoide.r was originally a monotypic genus based on L. pott.ri described from the Dry Tortugas by Shoemaker in 1933. In 1955, Barnard described a new species, L. pacifica, from the sponges in Newport Bay, California. Males of L. paci f ica are readily distinguished from all other Leucothoide.r by the convex palm of gnathopod 2 in adult males. Barnard (1974) also described two new species from the Pacific, L. torrida and L. yarrega. Two other species of Leuco- thoide.r were also presented by Barnard, "Leucothoide.r species V from Logger- head Key" and "Leucothoide.r species Q from Albatross 2406" from Loggerhead Key and the Gulf of Mexico respectively. These latter two species are very close to L. pott.ri, differing only in the placement of setules on the margin of coxa 1. The material at hand fits Barnard's species from Loggerhead Key. As Shoemaker's figured specimen of L. pott.ri cannot be located for comparison, the present material will be referred to as L. pottsi until sufficient material can be gathered to establish the validity of the other Caribbean species. .