Oikopleura fusiformis, Fol, 1872

Franco, P., Dahms, H. - U., Lo, W. - T. & Hwang, J. - S., 2017, Pelagic tunicates in the China Seas, Journal of Natural History 51 (15 - 16), pp. 917-936 : 928-929

Oikopleura fusiformis

Morphology

Medium sized (the body length is 1.0– 1.4 mm) with an elongated and narrow trunk. Tail with narrow muscular bands and lacking sub-chordal glands. The trunk gets its characteristic aspect in this species from a large diverticulum (caecum), extending from the left stomach lobe. The rectum and intestine are long and narrow. The mouth has a pronounced lower lip and is turned upwards. There are no buccal glands and the endostyle is short and broad. The ovary is of rather flat shape; the paired testes are long, covering most of the stomach (authors’ personal observations ( Marine Species Identification Portal 2017).

Biogeography

Semi-cosmopolitan in temperate and tropical waters of the Atlantic, Pacific, and Indian Oceans; also found in the Red Sea and Mediterranean Sea. In the North Atlantic Ocean, occasionally transported with the Gulf Stream north to 60°N . It is absent from the Arctic Ocean (WoRMS Editorial Board 2017).

Family FRITILLARIIDAE (Larvacea) Fritillaria aberrans

Morphology

Trunk elongate, up to 6.0 mm long. Mouth simple with the upper lip somewhat protruding. Presence of two small pharyngeal cells. The axis of the alimentary tract is oblique. Testis is cylindrical, behind one spherical to ellipsoidal ovary. Musculature of tail is broad (authors’ personal observations ( Marine Species Identification Portal 2017).

Biogeography

It was recorded from the Indian Ocean, the Red Sea, Antarctic Ocean and Pacific Ocean. It is also present in the Mediterranean Sea (WoRMS Editorial Board 2017).

Family DOLIOLIDAE (Thaliacea) Doliolum denticulatum

Morphology

Body length is up to 2 mm. Eight muscle bands (M) are present in the gonozooid which is characterised by a dextral arched intestine. Branchial septum is remarkably arched from MII dorsally to MV; then it curves at 2/3, running to M3 ventrally. Endostyle is short. Testis is situated horizontally in front of MIII, long and swollen. Oozooids with four pairs of gill slits and nine muscle bands. Intestinal tube is stretched sagittally and the oesophageal concavity is oriented downwards. Nurses without visceral mass, except for a heart which is barrel shaped. Budding is held on the dorso-ventral processes. MII –MVIII are fused to a continuous sheet (authors’ personal observations; Godeaux et al. (1998).

Biogeography

Widespread in all oceans from 40°N to 40°S (following the 10°C isotherm in the north and the 15°C isotherm in the south) (WoRMS Editorial Board 2017).