Four new species of didymozoid trematodes from China.

This paper deals with five species of digenetie trematodes of the. family Didymo-zoidae collected from marine fishes in the East and South China Seas. Of the five species four are new to science and Nematobothrium filiforme Yamaguti 1934 a new record from China. The type specimens are deposited in the Institute of Oceanology, Acade-mia Sinica.Didymozoon longicollopsis, sp. nov. (fig. 1)Only a single specimen was secured in a cylindrical cyst on the outer wall of intestine from one of the twenty-eight Priacanthus tayenus Richardson collected from Baimajing, Hainan Island, Guangdong Province, on May 19, 1964.This species resembles Didymozoon longicolle Ishii 1935, but differs from the latter in having no pharynx and in its testes being elongated, its receptaculum seminis near the center of hind-body, and its vitellarine gland divided into an anterior and a posterior branches.Didymozoon pneumatophori, sp. nov. (fig. 2)Only one cyst was collected on the gill cover of Pneumatophorus japonicus (Houttyn) from Lianyungang, Jiangsu Province, on May 7, 1973 and 1, 1, 2, 3 cysts were collected respectively from four of the ten P. japonicus from Ningho, Zhejiang Province, on June 6, 1975.This species is similar to Didymozoon priacanthi Ku et Shen 1965, but is different from that species in its larger oral sucker and its ovary and vitelline gland extending from the anterior and posterior end of hind-body respectively to meet the receptaeul-um seminis, which is situated near the center of hindbody. Didymocystoides dolichorctus, sp. nov. (fig. 3, 4)One cyst was obtained from the gill filaments of one of the four examined Priacanthus tayenus Richardson and 1, 2, 2 cysts were obtained from the gill filaments of three of the four examined P. macracanthus Cuvier et Valenciennes. Both hosts were caught from Baimajing, Hainan Island, Guangdong Province, on May 22, 1964.This species bears a resemblance to' Didymocystoides alalongae Yamaguti 1970, but is distinguished from the latter by its smaller body larger oral sucker and esophagus, unbranched ovary and vitelline gland, and by the absence of pharynx. Its much elongated testes have not been seen in other known species of this genus.Gonapodasmius hainanensis, sp. nov. (fig. 5, 6)Three groups of worms were found on the gill filaments of a Trisotropis der-mopterus (Temminck et Schlegel) collected from Baimajing, Hainan Island, Guangdong Province, on May 24, 1964.This species resembles both Gonapodasmius menpachi Yamaguti 1970 and G. spilonopteri Yamaguti 1970. It differs from G. menpachi in its female being larger than the male, and its female aeetabulum being much distant from the intestine ceca and smaller than the oral sucker. Prom G. spilonopteri it differs in its body being larger in size, the commencement of its testes being distant from the posterior end of body, and its receptaculum seminis being indistinct. Eggs of the new species are smaller than those of its congeners.