Generalized larva of Cerebratulus cf. marginatus and Cerebratulus sp. "spade head", with large episphere and juvenile with two eyes and a caudal cirrus. The juvenile's anterior end is tilted upwards toward the apical organ, and the entire body occupies an off-center position toward the posterior lobe.
Cerebratulus cf. marginatus species complex
The larvae of Cerebratulus cf. marginatus and a closely related and undescribed species (Cerebratulus sp. "spade head") are very large and have a rounded dome, and a juvenile with caudal cirrus and two eyes. Adults of C. cf. marginatus species also have a pair of eyes, which are only noticeable in younger lighter colored individuals (Maslakova pers. observation). Cerebratulus cf. marginatus is the most common cerebratulid species on the mudflats of Coos Bay, OR and False Bay, WA. We have found pilidia of this species in the plankton in Coos Bay, OR. Pilidia of this species often have several "clear inclusions" near the apex of lateral lappets and lobes (see images below).
Cerebratulus cf. marginatus
Sequence Data: 16S, COI
Observed in Coos Bay: April, May, July
Cerebratulus marginatus is a common heteronemertean species on the southern OR coast and larvae can be reared from ripe adult specimens (although not as easily as from Maculaura alaskensis). The larvae, however, are a bit less common than the adults and are found in late spring/early summer. They are recognizable by their large and wide episphere, lack of body color or pigment pattern and a juvenile that is tilted upwards. The larvae of C. cf. marginatus resemble the larvae of another Cerebratulus species, currently undescribed – Cerebratulus sp. “spade head” (below). However, the reproductive timing is different: C. cf. marginatus larvae have been found April-July, and the larvae of C. sp. "spade head" — in October. Also larvae of C. cf. marginatus have several unusual-looking clear "marble-like" inclusions near the apices of larval lobes and lappets.
Young larvae of Cerebratulus cf. marginatus, coll. May (left and middle) and July 2013. Scale bars 100 µm.
Cerebratulus sp. "spade head"
Sequence Data: 16S, COI
Observed in Coos Bay: October
This larva belongs to an undescribed Cerebratulus species which is closely related to C. cf. marginatus which we call Cerebratulus sp. “spade head”. The larvae and adults of this species look very similar to C. cf. marginatus. They have a wide episphere and large vestibule, the juvenile is tilted upward and possesses two small eyes and a caudal cirrus. So far, the larvae of this species have only been collected in October as opposed to the larvae of C. cf. marginatus which are usually found in the spring and summer. The larvae of this species will readily eat cultured Rhodomonas lens and Terra Hiebert maintained a single larva (above) for two weeks at which point the juvenile metamorphosed and ingested its larval body (below).
Larva collected 22 Oct 2012. Scale bar 100 µm.
05 Nov 2012: post-metamorphosis. Scale 100µm.
Same larva on 05 Nov 2012.
General larval morphology = hat - shaped
Pilidial characters = large episphere without spots
Episphere = dome-shaped