Bicellariella ciliata (Linnaeus, 1758)
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publication ID |
https://doi.org/ 10.1007/s13127-022-00562-y |
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persistent identifier |
https://treatment.plazi.org/id/03AC87AF-FFBF-FFBF-FC98-C935873498C8 |
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treatment provided by |
Felipe |
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scientific name |
Bicellariella ciliata |
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Bicellariella ciliata View in CoL ( Figs. 2A View Fig , 13 View Fig , 18D)
Avicularium
Cystid and mandible The small bird’s head-shaped adventitious avicularia ( Fig. 13A View Fig ) are attached to the autozooidal surface by a short cylindrical stalk. The cystid has a short pointed rostrum with a curved tip, and the small proximally to adductor in C; diaphragm and longitudinal muscles of tentacle sheath are enlarged in inset). D Tangential section of avicularium showing basal part of raised mandible (opening in transverse wall shown by arrowhead). In C, E and F dotted line indicates borders of avicularian mandible. Abbreviations: dm, diaphragm, mab1, distal abductor, mab2, proximal paired abductors, mad, adductor, md, mandible, rm, retractor muscles, vp, vestigial polypide semi-rounded posmandibular area that is covered by the frontal membrane.
The avicularian mandible is triangular with a pointed, curved tip and prominent sclerite ( Fig. 13B View Fig ). It consists of the upper, lower, and transverse walls, and a narrow cavity inside. The latter communicates with the avicularian body cavity through the small circular opening in the transverse vertical wall ( Figs. 13D View Fig , 18D). The proximal margin of the upper mandibular wall is connected with the frontal membrane.
Polypide and muscular system The vestigial polypide is situated below the palate ( Figs. 13D View Fig , 18D). The uppermost part of the tentacle sheath wall contains the diaphragm consisting of 1–2 annular muscle fibers. We also detected 3–4 very short longitudinal muscle fibers in the middle part of the tentacle sheath wall ( Fig. 13E View Fig , inset). The polypide retractors consist of two striated fibers ( Fig. 13F View Fig ) that arise from the basal wall of the avicularian cystid and insert to the lower part of the tentacle sheath.
Four pairs of smooth abductors are present. Three pairs of larger proximal abductors are thick and short “triangular” muscle bundles of about the same size each. Each such abductor consists of several muscle cells ( Figs. 13C, F View Fig , 18D). Proximally, they anchor to the proximo-lateral cystid walls behind the adductor muscles, distally inserting to the frontal membrane. The attachment zones of these muscles are oriented under the obtuse angle in respect to each other. The distal abductors are two long muscle bundles that anchor to the lateral cystid walls in front of the adductors ( Fig. 13C, E View Fig ), running up and insert in the frontal membrane between the proximal edge of the mandible and the attachment zone of the proximal abductors.
The striated adductors are the largest muscles in the avicularium. Their bases occupy most of the basal cystid wall ( Figs. 13C, F View Fig , 18D). Distally, each muscle bundle continues to a tendon, which adjoins (but does not fuse with) a tendon of the second adductor. They run together and insert to the upper vestibular wall ( Fig. 13B View Fig ).
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