(Kieffer, 1913)
Body
Medium sized to large larvae up to 12.5 mm long. Living larvae red. Claws on the posterior parapods are simpel. No lateral and ventral tubules (Wiederholm, 1983; Moller Pillot, 1984a).
Head
The gula Gula unpigmented and ventral occipital margin are pale.
Antenna
The antenna consists of 5 segments. The basal segment is al long as or longer than the flagellum. Lauterborn organs are absent Cryptoch antenna.
Mentum
The mentum has one broad yellow median tooth and 6 pairs of lateral teeth. The outer tooth may be subdivided Cryptoch mentum 8. The ventromental plates as wide as or wider than the mentum and tapering lateraly. The striae are fine and simpel Figuur 12 Vallenduuk.
Labrum
SI is simpel and labral lamellae are absent Cryptoch labrum. The pecten epipharyngis consists of three lobes with a serrated margin. The premandible has 4-6 apical teeth.
Mandible
The mandible without a dorsal tooth. Apical tooth with 2 inner teeth. The pecten mandibularis is absent and seta interna with 4 branches, 2 smooth and 2 plumose.
Differential characteristics
The yellow median tooth, fused with the first of the six pairs of brown lateral teeth is distinctive for the genus Cryptoch mentum 8.
C. defectus can be separated from the other species with a pale gula by the LMO of 180 - 240 µm and a head length of 475 - 600 µm.