Larva of Lineus sp. "crecsent" collected in February 2013. Note central position and relatively small size of developing juvenile and relatively large anterior and posterior larval lobes. Scale bar 100 µm.
Lineus sp. "crescent"
Sequence Data: 16S, COI
Observed in Coos Bay: Jan-Feb
These larvae are easy to recognize. They are the larvae of Lineus sp. “crescent”, an undescribed nemertean species which we find amongst Phyllospadix sp. root masses in the rocky intertidal. We only found the adult once and it was a small nemertean, but had a distinctive white patch anteriorly in the shape of a crescent moon, not unlike a fingernail. When sorting a plankton sample, their larvae are very large and almost equally wide (lobe to lobe) as they are tall (apical tuft to lappet). Likewise, their anterior and posterior lobes are large, wide and floppy. The height from the lobes to the apical tuft is shorter than in other large pilidia which gives the episphere a wide stance. Despite the large size of the larval body, the juvenile nemertean develops immediately at the larval center and is quite small when compared to the larval body.
Young Lineus sp. "crescent" larva collected in February 2013. Note cephalic disc at 3 o'clock (in focus, left) and all three discs (cephalic, trunk and cerebral organ discs) surrounding larval esophagus. Scale bars 100 µm.