Microcosmus curvus Tokioka, 1954

KOTT, PATRICIA, 2003, New syntheses and new species in the Australian Ascidiacea, Journal of Natural History 37 (13), pp. 1611-1653 : 1649

Microcosmus curvus Tokioka, 1954

Microcosmus curvus Tokioka, 1954: 263 ; 1967: 251; Kott, 1990b: 289.

Microcosmus exasperatus Monniot and Monniot, 1987: 125 (part).

Microcosmus manaarensis Monniot and Monniot, 1996: 265 .

Microcosmus bitunicatus Monniot and Monniot, 2001: 348 .

? Not Microcosmus curvus: Renganathan, 1983: 929 .

Distribution. The species has a confirmed range in the Indo-West Pacific from the Tokara Is, the Marianas, Wake I., Palau Is, Heron I., French Polynesia and the Gulf of Manaar.

Remarks. Two species of Microcosmus with only six folds on each side of the body are known from the Indo-West Pacific. One is Microcosmus helleri Herdman, 1882 and the other M. curvus . Kott (1985) established the synonymy of M. helleri and M. manaarensis after examining their type specimens (BM 1887.2.4.44 and BM 1907.8.30.11, respectively) and M. helleri: Hastings, 1931 (BM 1930.12.17.4) and other material from the West Indies (BM 1931.5.4.3). The species characteristics are its six branchial folds on each side, absence of siphonal armature, four tough cartilaginous spoon-shaped valves at the base of the branchial siphon and a tough, fibrous atrial velum divided into two and sometimes forming pocket valves. The type of M. helleri has a naked test, while the M. manaarensis type has long hairs entangled with sand. Both types occur amongst the Australian populations, including some with a double test similar to what Herdman (1906) described. Microcosmus curvus Tokioka, 1954 has a similar double test. It is distinguished from M. helleri by its siphonal spines and the absence of branchial valves. Microcosmus manaarensis: Monniot and Monniot (1996) from the Philippines, although conspecific with the present species, has a double test like some specimens of M. helleri . Monniot and Monniot (2001) appear to have overlooked the present species when they erected M. bitunicatus (from the Philippines).

Microcosmus curvus: Renganathan, 1983 (the identification confirmed by F. Monniot) was recorded from the Gulf of Manaar. Neither siphonal spines not cartilaginous branchial valves are reported but the characters that are recorded do not distinguish these specimens from M. helleri . The presence of M. curvus outside the western Pacific is in doubt.