Syndesmis compacta sp. n. and Redescription of S. glandulosa Hyman 1960 (Turbellaria: Umagillidae) from Philippine Sea Urchins

Abstract

Syndesmis compacta sp. n. is described from the intestine and coelom of the Philippine sea urchin Echinometra oblonga. It differs from S. punicea Hickman 1956 from New Zealand in having an unilocular seminal bursa, a coiled ejaculatory duct, a smaller egg, white color in life, and its overall, small, compact form. Syndesmis glandulosa Hyman 1960 is redescribed with material from the Philippine urchins Diadema setosum and Echinothrix calamaris. Living specimens are white with a faint, red midline. All have five ventral, glandular papillae, and details of the seminal bursa-bursal canal complex differ from the original description. Turbellarians of the genus Syndesmis inhabit the intestine and coelom of echinoid echinoderms. Jennings (1971) recognized seven species, and three more were described by Komschlies and Vande Vusse (1980). Examination of sea urchins collected near Dumaguete City, Negros Oriental, Philippines, (approximately 660 km SSE of Manila) during January 1979 revealed five species of Syndesmis, including S. compacta sp. n. described below and S. glandulosa Hyman 1960. Details on prevalence and geographic distribution will be presented in a later paper. Syndesmis glandulosa was known previously only from Diadema setosum from Madagascar. Hyman was unable to describe completely the species or to provide information on living worms (e.g., color, shape, or location within host) because the material she received had been preserved crudely. Sea urchins were collected in 1 to 4 m of water at the Silliman University Marine Laboratory on Negros and the nearby, smaller islands of Siquijor, Sumilon, and Apo; all are within 30 km of Dumaguete City. Turbellarians were removed, held briefly in seawater, and fixed in AFA. Whole mounts were fixed with light coverslip pressure and stained with Delafield's hematoxylin. Specimens for sectioning were fixed without coverslip pressure, cut at 10 um, and stained with hematoxylin and erythrosin. Drawings were made with the Received 6 November 1979; accepted 4 January 1980. * Studies done at Silliman University Marine Laboratory, Dumaguete City, Philippines. t To whom reprint requests should be addressed. aid of a microprojector. Measurements are from six gravid S. compacta sp. n. and 20 gravid S. glandulosa. Measurements are in micrometers unless otherwise indicated, and range is presented with the mean in parentheses. Syndesmis compacta sp. n. (Fig. 1)