Microcosmus helleri Herdman, 1881

Lambert, Gretchen, Lee, Serina Siew-Chen & Teo, Serena Lay-Ming, 2021, Ascidians collected during the 2013 Singapore Strait International Marine Biodiversity Workshop, Zootaxa 4933 (1), pp. 1-38 : 29

Microcosmus helleri Herdman, 1881

Figure 11C, D

Tunic lumpy, tough, tan to light brown in color, usually heavily fouled. Siphons widely separated and directed away from each other; no siphonal spines. Four large oral flaps at base of branchial siphon, six tall branchial folds per side. Liver composed of parallel lamellae with surface papillae.

#1172, attached to Cnemidocarpa irene (specimen #1192). Small; 15 mm tall x 15 mm in width. Gonad in two sections on both sides, crosses gut on left side.

#4654, small, 2 cm in width; body out of tunic 16 mm wide. Small mytilid bivalve embedded in anterior tunic between the siphon bases.

Distribution: Australia, Guam, Indonesia, Sri Lanka, Malaysia, Singapore, E. Africa, Caribbean, Puerto Rico, Martinique, Brazil.

Detailed references with illustrations: Van Name (1945), Kott (1985), Monniot F. (2018c).Additional references: Monniot C. & Monniot F. (1994), Lambert (2003), Rocha et al. (2012), Lee et al. (2016).

Figures

FIGURE 11. A, B: Microcosmus exasperatus. A: whole animal right side, 1.2 cm in height; B: siphonal spines, largest 44 um long; C: Microcosmus helleri in tunic, 2 cm in width, showing opened edges of embedded bivalve (arrow); D: bivalve removed from host tunic; E: anterior end of small Pyura curvigona (2 cm total length) partially embedded in Polyandrocarpa rollandi colony; F: P. curvigona siphonal spines, longest 211 µm.