Microcosmus exasperatus Heller, 1878

Monniot, Françoise, 2010, Some new data on tropical western Pacific Ascidians, Zootaxa 2561 (1), pp. 1-29 : 25-27

Microcosmus exasperatus Heller, 1878

( Figures 20D , 25B , 27 )

Microcosmus exasperatus Heller, 1878:17 . Cole & Vorontsova:1998: 1 Fig.2 , Viet Nam. Rocha, Moreno, Metri: 2005: 470, with synonymy and distribution.

Material. Coll. N.J. Pilcher et al., Viet Nam, Con Dao Isl. , Con Son isl., Da Trang, 08°39.43’N – 106°36.37’E, 5m, 23/VII/2008, 0PHG 1603 bis ( MNHN S2 MIC 193 ) .

A single specimen ( Fig. 20D ), 35mm long, with a red tunic covered with epibionts was attached to Polycarpa argentata . The branchial sac ( Fig. 27A ) has 9 folds on the right side and 8 on the left side. The branchial formula on the right is:

E-1- 14 - 2- 18 -3- 17 -4- 18 -4- 22 -5- 22 -3- 24 -3- 21 -3- 14 -2-DL.

The digestive loop occupies a large part of the left body side. The left gonad crosses the intestine. The right gonad has 3 lobes ( Fig 27B .).

The siphonal spinules have a wide base narrowing to a sharp point and small denticles on the sides ( Fig. 25B )).

Microcosmus exasperatus is a widely distributed fouling species recorded warm waters in all oceans, and undoubtedly introduced in many localities. It was already known from Viet Nam.

Figures

FIGURE 2. A:Trididemnum cyclops. B: Trididemnum lanugineum n. sp. C: Trididemnum biglutinum from New Guinea. D: Trididemnum biglutinum from Palau.

FIGURE 20. A: Amphicarpa duploplicata. B: Polycarpa argentata. C: Polycarpa mytiligera. D: Microcosmus exasperatus.

FIGURE 25. Siphonal spinules: A: Pyura arenosa. B: Microcosmus exasperatus. Scale bars 10µm.

FIGURE 27. Microcosmus exasperatus: A: branchial sac, B: body.