Stereobalanus willeyi, Deland & Cameron & Rao & Ritter & Bullock, 2010
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publication ID |
https://doi.org/ 10.11646/zootaxa.2408.1.1 |
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publication LSID |
lsid:zoobank.org:pub:9BBB84BB-239C-41EA-9CFC-682449F96281 |
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persistent identifier |
https://treatment.plazi.org/id/101A87CA-FF81-FFA7-DBA6-FA49FA85F87B |
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treatment provided by |
Felipe |
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scientific name |
Stereobalanus willeyi |
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sp. nov. |
Stereobalanus willeyi View in CoL n. sp.
( Fig. 2D, E, I, J View FIGURE 2 ; Fig. 3 View FIGURE 3 )
Stereobalanus willeyi Ritter & Davis, 1904 View in CoL nom. nud.
Material examined. Three anterior fragments were found by Ritter ca. 1900 after dredging in extremely soft sandy mud at about 80 m depth in San Pedro Channel off the coast near Newport , Orange County, California. Holotype: Accession no. NMNH 71441 View Materials , Smithsonian Institution. Paratype: NMNH 1132794 View Materials .
External features. ( Fig. 2 D, E, I, J View FIGURE 2 ). Proboscis conical, cylindrical in section, ca. 1 cm long. Collar less than half length of proboscis and rather broader than long, with expanded rim at anterior edge. Four genital ridges distinct, column-like, confined to branchial region. Branchio-genital region slightly longer than proboscis. A prominent ventral keel seen in abdominal region. Proboscis is cream-colored; collar similar but somewhat lighter. Gonads in female bright yellow. Pharyngeal region, excepting gonads, almost same color as collar; abdomen nearly black; gills as seen from dorsal side, when gonads pressed aside, appearing black.
Internal features. ( Fig. 3 View FIGURE 3 ). Circular muscle layer of proboscis well developed, somewhat thicker than nerve-fiber layer of ectoderm. Longitudinal muscle fibers in well-defined radial plates ( Fig. 3A View FIGURE 3 ), particularly toward base of proboscis. Stomochord in form of tube without ventral caecum, with thick and even wall ( Fig. 3B View FIGURE 3 ). Stomochordal neck completely obliterated; stomochordal sheath extremely thick. Glomerulus very limited in development and much scattered, arising as two irregular masses from dorsal side of stomochordal sheath ( Fig. 3A View FIGURE 3 ). Proboscis cavity obliterated by musculature and glomerulus posteriorly. Cardiac vesicle rudimentary, lacking bifid tip. Proboscis vesicles with canals and pores, one on each side, reduced to mere trace; some communication between proboscis coelom and proboscis pore apparent through vesicles and canals, these all rudimentary. Proboscis skeleton also much reduced, with no keel and a small piece that is bluntly rounded anteriorly, continuing posteriorly into cornua ( Fig. 3C, D View FIGURE 3 ); cornua arising from posterolateral margins of skeletal body, hence widely separated from each other from their start, extending to posterior margin of collar.
Dorsal nerve cord of collar without any dorsal roots. Lumen of cord distinct in about its posterior third but not so in remainder of length. Collar canals and pores absent. Peribuccal coelom not present. Perihaemal cavities conspicuous, extending into neck. Caecum large, posteriorly directed, given off from ventral side of buccal cavity in collar region. This beginning anteriorly a short distance behind mouth as a broad deep trough that becomes more and more set off by attenuation of lateral walls of buccal cavity above it, until finally the walls close together, producing a well-defined ventral caecum in middle region of collar ( Fig. 3D View FIGURE 3 ); walls of caecum practically of same histological structure as buccal epithelium immediately adjacent to it.
About 70 branchial apertures on each side and no synapticulae. Parabranchial ridges prominent ( Fig. 3E View FIGURE 3 ). Branchial openings large, exposing gill-tongues to view. Ova rather large, ca. 0.5 mm diameter. A pair of lateral and pair of dorsal genital ridges starting immediately behind collar. A single pair of intestinal pores in abdominal region.
Remarks. Stereobalanus willeyi is clearly more closely related to S. canadensis ( Spengel, 1893) than to any other known species. It is sharply distinguished from S. canadensis by its color, the possession of a much larger number of branchial pores, the shape of the proboscis skeleton, the complete absence of the collar canals and pores, the caecum on the ventral side of the buccal cavity and the possession of intestinal pores.
In his manuscript account, Ritter said this of the derivation of the specific name: "I take great pleasure in dedicating this interesting form to Dr. Arthur Willey in whose extensive contributions to the Zoology of the South Pacific, the Enteropneusta had a liberal share."
The above description of S. willeyi is based mainly on the manuscript of Ritter. Ritter and Davis (1904) listed this species by name as one whose description was forthcoming, mentioning that it has two proboscis pores and could not be the parent of a tornaria larva they were studying. This being inadequate as an indication, the species cannot be regarded as having heretofore been published. The living authors of the present paper have examined the sections critically and have made a few changes in the description given by Ritter. The references to this name given in the synonymy clearly refer to the same specimens although no adequate indication is provided with which the species could be recognized.
The defining characters of Stereobalanus willeyi are listed below:
A. Proboscis conical, longer than broad.
B. No proboscis groove.
C. Longitudinal musculature of the proboscis is in radial plates.
D. Two minute proboscis pores on either sides of the dorsal midline.
E. Proboscis skeleton has no keel.
F. Posterior neuropore.
G. No peribuccal diverticula in the collar.
H. No collar canals.
I. 4 columnar genital ridges confined to the gill region.
J. 1 pair of esophageal pores.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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Stereobalanus willeyi
| Deland, C., Cameron, C. B., Rao, K. P., Ritter, W. E. & Bullock, T. H. 2010 |
Stereobalanus willeyi
| Ritter & Davis 1904 |