Heterochaerus sargassi ( Hyman, 1939 )

Hooge, Matthew D. & Tyler, Seth, 2008, Acoela (Acoelomorpha) from Bocas del Toro, Panama, Zootaxa 1719, pp. 1-40 : 5-6

cf. Heterochaerus sargassi ( Hyman, 1939)

( Fig. 2 B)

Amphiscolops sargassi: Hyman 1939 ; Marcus 1947 (p 161); Marcus 1949 (p 9); Marcus 1950 (p 44); Marcus 1952 (p 18); Marcus 1954 (p 15); Dörjes 1968 (p 87); Dörjes 1970 (p 262); Dörjes and Young 1973 (p 350); Dörjes and Karling 1975 (p 177); Hooge and Tyler 2001 (p 414).

Heterochaerus sargassi: Winsor 1990 (p 798); Hooge 2003 (p 275); Hooge and Rocha 2006 (p 1).

Material. Living immature specimens in squeeze preparation.

Locality. Isla Bastimentos (9°20.898’ N, 82°9.959’ W), from subtidal brown algae, and from plankton in Almirante Bay.

Description. Immature specimens ~640 µm in length and ~300 µm wide ( Fig. 2 B). With many gold-colored endosymbiotic zooxanthellae. Statocyst absent. Red eyespots visible at anterior end. Concentration of black concrements (in transmitted light) present at anterior tip. Small crustaceans present in digestive syncytium.

Remarks. The genera Amphiscolops and Heterochaerus are difficult to distinguish, especially in specimens lacking sexual organs. Heterochaerus sargassi was originally described by Hyman (1939) from specimens that lacked sexual organs. Marcus (1950) collected sexually mature specimens of H. sargassi from the coast of Brazil and described the reproductive organs. The presence of eyespots, concrements at the anterior tip, and lack of a statocyst lead us to believe that our specimens are in fact H. sargassi .

Figures

FIGURE 2. Photomicrographs of living specimens. A. Convoluta sp. B. cf. Heterochaerus sargassi.