The subfamily Notochthamalinae Foster and Newman, 1987, was proposed for members of the barnacle family Chthamalidae with elongated scuta and very narrow terga deeply interlocked, sometimes concrescent. Shell plates may become concrescent with age in some species. Soft part characters include card setae on some or all of cirri I to III, and mandible with or without combed lower edge. Poltarukha made further revisions in 1996.
Definition and Discussion
Notochthamalines have a shell wall of 8, 6, or 4 plates, reduction from the 8-plated condition is accomplished by suppression of the carinolatus II. In Chamaesipho only, plate number reduces to four during ontogeny by fusion of carinolatus I with the rostrolatus. Shell wall plates rarely become concrescent with age. The basis is membraneous, rarely partially calcareous. The scutum is elongate, tergum narrow, and deeply articulated. In a few species, scutum and tergum of same side may become concrescent with age.
1. Shell wall of 8 plates ...................................................................................................................................................... 2
a. Shell wall of fewer than 8 plates ...................................................................................................................................... 3
2. Rostrum and adjacent rostrolaterals partially fused, suture visible from inside only, basis calcareous; caudal appendages multi-segmented .................................................................................................................................................. Pseudoctomeris
a. All eight plates remain free, R-RL sutures visible from exterior, basis membraneous; caudal appendages absent ...... Octomeris
3. Shell wall of 4 plates .................................................................................................................................... Chamaesipho
a. Shell wall of 6 plates ..................................................................................................................................................... 4
4. Shell and/or opercular plates become concrescent with age .............................................................................................. 5
a. Shell and opercular plates do not become concrescent ..................................................................................................... 6
5. Shell and opercular plates become concrescent ......................................................................................... Nesochthamalus
a. Shell plates so not fuse, but scutum and tergum on each side become concrescent .............................................. Rehderella
6. Tergal depressor muscles set in overhanging pit without crests .................................................................... Notochthamalus
a. Tergal depressor muscle attachment with crests ..................................................................................... Hexechamaesipho
Environment and distribution
Members of the subfamily may be found in the upper littoral zone of tropical western Pacific Ocean and South Australia, New Zealand, South Africa (Octomeris angulosa), west coast of South America (Notochthamalus scabrosus) and Falkland Islands. Distribution appears to be relictual in part.
