Two New Species of Malmiana (Hirudinea: Piscicolidae) from Oregon Coastal Waters

Abstract

Malmiana virida sp. n., parasitic on buffalo sculpins, Enophrys bison, in Yaquina Bay estuary, and Malmiana diminuta sp. n., a parasite of rockfishes, Sebastes spp., and cabezon, Scorpaenichthys marmoratus, are described. Malmiana virida reaches a length of 30 mm and resembles Malmiana scorpii (Malm) except in structure of the male reproductive system. Malmiana diminuta attains a length of only 15 mm and is usually reddish-brown with marginal, metameric clusters of yellow pigment granules. Cocoons of M. virida contain from 2 to 4 eggs, but those of M. diminuta contain only 1 egg. After a long and somewhat confusing history (Moore and Meyer, 1951; Srivastava, 1966; Richardson, 1970) Malmiana Strand 1942 gained acceptance as the generic name for a group of marine leeches originally placed in Ottonia by Malm (1874). Recently, however, Epshtein (1962, 1967), unfortunately without discussion, synonymized Malmiana and Heptacyclus Vasileyev 1939 and employed Heptacyclus as the generic name since it had priority. The two genera do appear very similar, but Srivastava (1966) disagreed with Epshtein's synonymy and separated the genera on the basis of differences in annulation and structure of the coelomic system. However, Srivastava in his description of H. myoxocephali examined only three preserved specimens. A thorough study of the anatomy and biology of both species of Heptacyclus is badly needed before the relationship between Malmiana and Heptacyclus can be determined with certainty, and recent authors (Sawyer et al., 1975; Kahn and Meyer, 1976) have continued to employ Malmiana as a generic appellation. That convention will be followed here. Two species of marine leeches, both assigned to Malmiana, have been collected in Oregon coastal waters for a number of years. The first, Malmiana virida sp. n., parasitic behind the pectoral fins of the buffalo sculpin, Enophrys bison Girard, occurs throughout the year, but only in the lower portion of Yaquina Bay estuary. The second species, Malmiana diminuta sp. n., has been present in the public aquarium at Oregon State University's Marine Received for publication 13 July 1976. * Present address: Normandeau Associates, Inc., Nashua Road, Bedford, New Hampshire 03102. Science Center for many years. Although attempts have been made to eliminate this species, it has persisted and is often present in very high numbers. Members of the genus Sebastes, especially S. melanops, are preferred hosts in the aquarium, but the leeches also occur on the skin and fins of cabezon, Scorpaenichthys marmoratus, and ling cod, Ophiodon elongatus. This species also occurs periodically in the Vancouver Public Aquarium, Vancouver, B. C., Canada, where it infests rockfishes, Sebastes spp., the sculpins Enophrys bison and Myoxocephalus polyacanthocephalus, Pacific halibut, Hippoglossus stenolepis, and ling cod. Leeches resembling this species were also observed by the author on rockfishes in the Steinhart Aquarium, San Francisco, California, but none was collected. In nature it has been observed off the central Oregon coast on S. melanops, and specimens were collected from a cabezon in Puget Sound, Washington. Leeches of this species attach to fins or body, but have never been observed in the mouth or gill cavity. The following descriptions are based upon the examination of hundreds of specimens, both living and fixed in 10% formalin, and upon 10 jum transverse, sagittal, and frontal sections of mature individuals fixed in Bouin's fluid and stained with hematoxylin and eosin. All measurements are in mm unless otherwise