Species accounts

No common name

Dicyema acuticephalum

FAMILY Dicyemidae

TAXONOMY

Dicyema acuticephalum Nouvel, 1947, Japan.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Dicyema acuticephalum is characterized by the presence of four propolar and metapolar cells. In this genus, cells of the propolar tier are opposite cells in the metapolar tier. Adults are up to 0.03 in (800 pm) long. Vermiform embryos are approximately 0.002 in (50 pm) long. There are 16-18 peripheral cells. The calotte is bell shaped. Infusoriform embryos consist of 37 cells and are approximately 0.001 in (30 pm) long.

DISTRIBUTION Japan.

HABITAT

Renal sacs of Octopus vulgaris. BEHAVIOR

Vermiform rhombozoans and infusoriform embryos swim with their cilia. There appears to be positive thigmotaxis to renal appendages in the vermiform stages.

FEEDING ECOLOGY AND DIET

Absorption of nutrients from the urine of hosts.

REPRODUCTIVE BIOLOGY

Adults have a single hermaphroditic gonad, the infusorigen. Approximately nine egg-line cells (oogonia primary oocytes) and 16 sperm-line cells (spermatogonia, primary spermatocytes, secondary spermatocytes, sperm) usually are found in an infu-sorigen.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Dicyema Microcyema

I Dicyema acuticephalum I Dicyemodeca deca I Microcyema vespa

No common name

Dicyemennea antarcticensis

FAMILY Dicyemidae

TAXONOMY

Dicyemennea antarcticensis Short and Hochberg, 1970, Antarctic Ocean.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Dicyemennea antarcticensis is characterized by the presence of four propolar and five metapolar cells. The body length of adults is up to 0.2 in (5,500 pm). The body length of vermiform embryos is approximately 0.01 in (300 pm). There are 34-36 peripheral cells. The calotte is triangular in the side view and pointed to rounded in the anterior view. Infusoriform embryos consist of 39 cells. The body length of infusoriform embryos is approximately 0.002 in (51 pm).

DISTRIBUTION Antarctic Ocean.

HABITAT

Renal sacs of the Antarctic octopus (Pareledone turqueti). BEHAVIOR

Vermiform rhombozoans and infusoriform embryos swim with their cilia. There appears to be positive thigmotaxis to renal appendages in the vermiform stages.

FEEDING ECOLOGY AND DIET

Absorption of nutrients from the urine of hosts.

REPRODUCTIVE BIOLOGY

Adults have a single hermaphroditic gonad, the infusorigen. Approximately 10 egg-line cells (oogonia primary oocytes) and four sperm-line cells (spermatogonia, primary spermatocytes,

Secondary Spermatocyte

secondary spermatocytes, sperm) usually are found in an infu-sorigen.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

No common name

Dicyemodeca deca

FAMILY

Dicyemidae

TAXONOMY

Dicyemodeca deca McConnaughey, 1957, northeastern Pacific Ocean (Washington, United States).

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Dicyemodeca deca is characterized by the presence of four propolar and six metapolar cells. The body length of adults does not exceed 0.04 in (1,000 pm). The body length of vermiform embryos is approximately 0.002 in (40-60 pm). There are 23 or 24 peripheral cells. The calotte is disk shaped. Infusoriform embryos consist of 35 cells and are approximately 0.001 in (33 pm) long.

DISTRIBUTION

Northeastern Pacific Ocean.

HABITAT

Renal sacs of Octopus dofleini.

BEHAVIOR

Vermiform rhombozoans and infusoriform embryos swim with their cilia. There appears to be positive thigmotaxis to renal appendages in the vermiform stages.

FEEDING ECOLOGY AND DIET

Absorption of nutrients from the urine of hosts.

REPRODUCTIVE BIOLOGY

Adults have two infusorigens. Approximately 16 egg-line cells (oogonia primary oocytes) and 15 sperm-line cells (spermato-gonia, primary spermatocytes, secondary spermatocytes, sperms) usually are found in an infusorigen.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

No common name

Microcyema vespa

FAMILY

Conocyemidae

TAXONOMY

Microcyema vespa van Beneden, 1882, English Channel.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Microcyema vespa is characterized by an irregular shape in adults; they lack external cilia and have a syncytiumal peripheral cell. The body length of adults is up to 0.03 in (800 pm). The body length of vermiform embryos is approximately 0.001 in (25 pm). There are 10 peripheral cells. In vermiform embryos the calotte is a syncytium containing six nuclei. Infusoriform embryos consist of 39 cells. The body length of infusoriform embryos is approximately 0.001 in (26 pm).

DISTRIBUTION

English Channel, Mediterranean Sea. HABITAT

Renal sacs of Sepia officinalis.

BEHAVIOR

Vermiform embryos and infusoriform embryos swim with their cilia. There appears to be positive thigmotaxis to renal appendages in the vermiform stages.

FEEDING ECOLOGY AND DIET Absorption of nutrients from the urine of hosts.

REPRODUCTIVE BIOLOGY

Adults have approximately 10 infusorigens. Approximately 9 egg-line cells (oogonia primary oocytes) and 8 sperm-line cells (spermatogonia, primary spermatocytes, secondary spermato-cytes, sperms) usually are found in an infusorigen.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Resources

Books

Hochberg, F. G. "Diseases Caused by Protistans and

Mesozoans." In Diseases of Marine Animals. Vol. III, edited by Otto Kinne. Hamburg: Biologische Anstalt Helgoland, 1990.

Periodicals

Furuya, Hidetaka. "Fourteen New Species of Dicyemid

Mesozoans from Six Japanese Cephalopods, with Comments on Host Specificity." Species Diversity 4 (1999): 257-319.

McConnaughey, Bayard H. "Two New Mesozoa from the Pacific Northwest." Journal of Parasitology 43 (1957): 358-61.

Nouvel, Henri. "Les Dicyémides. Systématique, générations, vermiformes, infusorigène et sexualité." Archives de Biologie, Paris 58 (1947): 59-220.

Short, Robert B., and F. G. Hochberg. "A New Species of Dicyemennea (Mesozoa: Dicyemidae) from Near the Antarctic Peninsula." Journal of Parasitology 56 (1970): 517-22.

van Beneden, Edouard. "Contribution à l'histoire des

Dicyémides." Archives de Biologie, Paris 31 (1882): 195-228.

Hidetaka Furuya, PhD

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