Observations on the reproduction and development of Liothyrella neozelanica Thomson 1918 (Terebratulacea, Articulata, Brachiopoda)

Mature individuals of the terebratulid brachiopod Liothyrella neozelanica Thomson, collected from Doubtful Sound on 25–26 February 1990 at Campbell Kingdom, spawned in the laboratory. The females brooded their opaque, white zygotes, embryos and larvae in the space bounded by the brachial membrane and its associated cirri in the apical region of the median spiral arm of the plectolophe. The coeloblastula gastrulated by invagination. The circular blastopore gradually elongated during gastrulation. Cilia, which first appeared during the gastrula stage, completely covered the embryo and persisted throughout larval life. The cylindroid gastrula developed into a wedge‐shaped larva, which returned to a cylindroid shape before the mantle fold appeared. Two grooves formed on each side of the mantle fold to constrict the larva into a three‐lobed body without eye spots. An occasional two‐lobed stage intervened whenever the two grooves developed asynchronously. Three‐lobed larvae could be classified by morphological features into early, late and pre‐settlement stages. Large ova developed into large larvae or occasionally into large incomplete larvae. Small ova produced miniature but otherwise normal larvae and some miniature incomplete larvae. Incomplete larvae did not differentiate further, had no pedicle lobe, and soon died. The reproduction and development of this species were discussed.

Keywords:

• Liothyrella neozelanica
• Brachiopoda
• articulate
• terebratulid
• reproduction
• larval development

Notes

Portobello Marine Laboratory, Portobello, New Zealand. Present address: 144 Pasir Ris Road, Singapore 1851.