Microcosmus exasperatus, HELLER, 1878

Monniot, Claude, 2002, Stolidobranch ascidians from the tropical western Indian Ocean, Zoological Journal of the Linnean Society 135 (1), pp. 65-120 : 105-106

publication ID

https://doi.org/ 10.1046/j.1096-3642.2002.00017.x

persistent identifier

https://treatment.plazi.org/id/436F3F3C-FFF8-FF87-FF78-F975FB2F1F8F

treatment provided by

Carolina

scientific name

Microcosmus exasperatus
status

 

MICROCOSMUS EXASPERATUS HELLER, 1878 View in CoL ( Fig. 31 View Figure 31 )

Microcosmus exasperatus: Kott, 1985: 348 View in CoL – Australia, and synonymy; Monniot C., 1983: 1035 – Guadeloupe, 1989: 479, fig. 2, pl. 1 A – New Caledonia.

Microcosmus pupa ( Savigny, 1816) View in CoL : Monniot, 1973: 58 part, fig. 4A – specimen from Eilat.

Material

Suez, coll. R. PH. Dollfus, 1928.

Gulf of Aden.

Madagascar: Nosy-Be, 27 m, coll. P. Laboute, 1992.

Mozambique: Ibo Island, coll. C. Monniot, 1995.

Yemen: Socotra Island, coll. C. Monniot, 1997.

Description

The body shape varies with the substrate. The moreor-less red tunic may be naked or with epibionts; it is always wrinkled. The tunic is not thick but resistant, and has a nacreous lining. The siphons are short.

Despite its strong musculature, the body wall is thin and reveals the internal organs. The muscles form large bundles that issue from the siphons, and regularly cross each other.

The ramified tentacles arise at the base of a large velum. The dorsal tubercle is U-shaped with the anterior horns slightly rolled inwards; it lies in a dorsal V of the prepharyngeal band.

There are eight-to-nine high branchial folds on each side of a smooth edged dorsal lamina. The stigmata are cut by parastigmatic vessels.

The gut makes a closed primary loop ( Fig. 31A–D View Figure 31 ) leading to a dorsally curved intestine that adheres to the dorsal lamina. The anus is smooth-edged.

One gonad lies on each side ( Fig. 31A–D View Figure 31 ), made of three or four massive lobes linked only by the gonoducts. The left gonad crosses the intestine ( Fig. 31A–D View Figure 31 ). Male and female papillae are short and close together and protrude from the body wall.

There are no endocarps on the internal layer of the body wall itself, but sometimes one or two of them lie on the ventral side of the stomach.

Filiform papillae cover a wide field around the base of the cloacal siphon.

Remarks

Microcosmus exasperatus View in CoL is cosmopolitan in warm waters. It differs from Microcosmus pupa ( Savigny, 1816) View in CoL by the absence in the former of endocarps and the shape of its gonads, made of lobes in a line.

MICROCOSMUS MADAGASCARIENSIS MICHAELSEN, 1918 View in CoL ( Figs 27D View Figure 27 , 32 View Figure 32 )

Microcosmus madagascariensis, Michaelsen, 1918: 20 View in CoL – Madagascar, Nosy-Be; Vasseur, 1969, – Madagascar, Tulear.

Not Microcosmus agglutinans Hartmeyer, 1919: 26 View in CoL

Not Microcosmus madagascariensis: Hartmeyer & Michaelsen, 1928: 398 View in CoL ; Kott, 1985: 35.

Material

Madagascar, Nosy-Be, coll. R. Plante, 1967.

Description

The single specimen is 16 mm in diameter. The tunic is encrusted with coarse sediment and projects some long, hair-like extensions also encrusted with sand. The short siphons diverge at 90°. The siphonal spinules are very sharp spines issued from a wide base ( Fig. 27D View Figure 27 ).

The body wall is rendered opaque by a dense musculature regularly distributed over the whole body. The oral velum is covered with button-like papillae.

Several orders of oral tentacles alternate; the largest tentacles have three orders of branching. The C-shaped dorsal tubercle opens to the left in the middle of a deep V of the prepharyngeal band ( Fig. 32D View Figure 32 ). The peritubercular area is papillate. The dorsal lamina is smooth.

The branchial sac has seven high folds on each side, overlapping each other. The formula is:

R

Departamento de Geologia, Universidad de Chile

V

Royal British Columbia Museum - Herbarium

Kingdom

Animalia

Phylum

Chordata

Class

Ascidiacea

Order

Stolidobranchia

Family

Pyuridae

Genus

Microcosmus

Loc

Microcosmus exasperatus

Monniot, Claude 2002
2002
Loc

Microcosmus exasperatus: Kott, 1985: 348

Kott P 1985: 348
1985
Loc

Microcosmus pupa ( Savigny, 1816 )

Monniot C & Monniot F 1973: 58
1973
Loc

Microcosmus madagascariensis: Hartmeyer & Michaelsen, 1928: 398

Kott P 1985: 35
Hartmeyer R & Michaelsen W 1928: 398
1928
Loc

Microcosmus agglutinans

Hartmeyer R 1919: 26
1919
Loc

Microcosmus madagascariensis, Michaelsen, 1918: 20

Michaelsen W 1918: 20
1918
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