Rhamphostomella ovata (Smitt, 1868)
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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-FFA3-FFA4-FC98-CE3A873A9873 |
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treatment provided by |
Felipe |
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scientific name |
Rhamphostomella ovata |
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Rhamphostomella ovata View in CoL ( Figs. 1C View Fig , 9 View Fig , 18A)
Avicularium
Cystid and mandible Small suboral adventitious avicularia are situated slightly obliquely, directly below the proximal upper part of image). C, D, inset Muscular elements of avicularium (frontal views) (note diaphragm and longitudinal muscles of tentacle sheath in inset). In C and D dotted line indicates borders of avicularian mandible. Abbreviations: dm, diaphragm, mab, abductor, mad, adductor, md, mandible, ts, tentacle sheath, vp, vestigial polypide edge of the autozooidal orifice ( Fig. 9A View Fig ). The avicularian cystid is oval in a frontal plane, with a crossbar, the cystid is immersed in the autozooidal frontal shield.
The mandible is semicircular, with the thickened peripheral sclerite bearing small denticles ( Fig. 9D View Fig ). Proximally, the upper and the lower walls of the mandible are connected by a narrow vertical wall.
Polypide and muscular system The vestigial polypide consists of the oval tentacle sheath with rudimentary lophophore inside and elongated ganglion ( Fig. 9B, D View Fig ). The polypide is situated in the distal part of the cystid, in front of and in between the adductor muscles ( Figs. 9B, C View Fig , 18A). The wall of the tentacle sheath includes diaphragmatic muscles whose fibers form a narrow “cone” in its uppermost part ( Fig. 9C View Fig , inset), and seven thin longitudinal muscle fibers. The upper ends of the longitudinal fibers intersect with the annular muscles of the lower half of the diaphragm. The distal ends of the retractor muscles insert to the lower part of the tentacle sheath.
The paired smooth abductor muscles are much smaller than the striated adductors and situated behind the latter ( Figs. 9C View Fig , 18A). Abductors are very compact and closely adjoining. Each abductor consists of about 10 short muscle fibers of about the same length. Proximally, they are anchored to the cystid wall in the proximal part of the avicularium, and their upper ends insert to the frontal membrane. Two zones of their attachment are short, narrow, and parallel to each other.
The upper ends of two large striated adductors are attached to the upper vestibular wall behind the sclerite by a pair of tendons slightly expanding near the sites of attachment. These muscles occupy most of the cystid volume, and their basal attachment zones cover most of the basal and the lateral walls of the cystid ( Fig. 9B, C View Fig ).
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