Glossobalanus williami, Cameron, Christopher B. & Ostiguy, Angélica, 2013
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https://doi.org/ 10.11646/zootaxa.3630.1.5 |
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lsid:zoobank.org:pub:C8213487-E392-4E16-9D81-51548F88E976 |
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https://doi.org/10.5281/zenodo.6159055 |
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https://treatment.plazi.org/id/1B379B4A-FFF9-197B-FF7F-7B64FD52C6C4 |
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Plazi |
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scientific name |
Glossobalanus williami |
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sp. nov. |
Glossobalanus williami View in CoL n. sp.
( Fig. 2 View FIGURE 2 )
Etymology. The name honors G.F.G. William of Reed College, Portland, who donated several fixed specimens taken from the Oregon coast to the Bullock collection.
Material examined. Holotype: USNM 1192961 (T.H. Bullock accession no. 543-1), comprising nine slides. Only two specimens, one complete, were originally collected; the second is in too poor a shape to be formally designated a paratype.
Description. Whole living specimen 13 cm long, proboscis relatively short at 2.5 mm, collar 1.5 mm long. Proboscis of live specimen cream to very light tan in colour. (Data for colour and length of live worm taken from field notes made by G. Ridgel in 1958.)
Longitudinal musculature of proboscis arranged in radial bundles. Nerve-fiber layer thicker than circularmuscle-fiber layer. Ventral septum of proboscis extending nearly to tip of stomochord anteriorly but not reaching ventral wall of proboscis in this region ( Fig. 2 View FIGURE 2 A). No dorsal septum; dorsal proboscis coelom separated into right and left only in peduncular region by cardiac vesicle. Anteriorly, cardiac vessel coextensive with stomochord. Further posteriorly, cardiac vescicle is quite roomy, reaching dorsal wall. Glomerulus very poorly developed, confined to sides, especially at junction of stomochord and cardiac vesicle ( Fig. 2 View FIGURE 2 B). Anteriorly it extends a little beyond tip of stomochord; two halves of glomerulus confluent. Stomochord lumen extending clearly to tip. Stomochord circular in cross section in anterior region; no distinct ventral or ventrolateral blind pouches (caeca) except for moderate ventromedian bulging. Neck of stomochord with discrete lumen. Skeleton with no anterior spine, and no sharp and deep keel ( Fig. 2 View FIGURE 2 C); a characteristic appearance in transverse section with a broad and obtuse ventral part. Only left proboscis canal present, opening out through discrete left proboscis pore ( Fig. 2 View FIGURE 2 C). Perihaemal cavities extending a little anterior to proboscis pore. Peduncle very delicate.
Dorsal septum of collar complete anteriorly ( Fig. 2 View FIGURE 2 D); ventral septum confined only to posterior extremity of collar. No anterior neuropore, but posterior neuropore present ( Fig. 2 View FIGURE 2 F). Collar nerve cord lacking lumen or lacunae; no dorsal roots either. Skeletal cornua confined only to anterior third of collar, turning down sharply and extending three quarters of length down circumference of buccal cavity ( Fig. 2 View FIGURE 2 E). Collar canals well developed, opening out along with first gill pouches ( Fig. 2 View FIGURE 2 F).
In pharyngeal region, branchial part of pharynx occupying dorsal 2/3, with non-branchial part constituting ventral 1/ 3 in transverse section. Branchial openings dorsolateral, quite widely open, conspicuous and superficial (not in deep groove) ( Fig. 2 View FIGURE 2 G). Postbranchial canal discrete, on right side of digestive part of posterior region of branchial gut. Gonads containing vitellogenic oocytes beginning only 3 mm behind collar. Only primary lateral gonads present; dorsal gonads absent. No clear-cut genital ridges, gonads lateroventral in position, appearing as single sacs ( Fig. 2 View FIGURE 2 H). Gonadal openings ventral to gill openings.
Type locality. North Bay, Cape Arago, Coos County, Oregon. Collected by G. Ridgel 30 July 1958.
Remarks. The present form is quite distinct from the other three species occurring on the west coast of North America. It differs from both G. hartmanae and G. barnharti in the possession of the following characters: circularfiber layer notably thicker than nerve-fiber layer in proboscis; anterior extent of glomerulus; stomochord circular in cross section anteriorly; absence of ventrolateral pouches in stomochord; almost-flat anterior face of proboscis skeleton; form of keel of skeleton; left proboscis pore; complete dorsal septum in collar; absence of dorsal nerve roots in collar; absence of lumen or lacunae in collar cord; larger size of branchial part of pharynx in transverse section; gonads starting at considerable distance posterior to collar; absence of dorsal gonads. Likewise the present form differs from G. berkeleyi in the following characters: absence of genital ridges; possession of discrete lumen throughout length of stomochord; absence of ventrolateral blind pouches in stomochord; very different structure and arrangement of proboscis skeleton; extent of skeletal cornua in collar; complete dorsal septum in collar; absence of dorsal nerve roots in collar; appearance of collar nerve cord in transverse section.
Glossobalanus williami is also sufficiently different from all other known Glossobalanus species to warrant recognition as a new species. Its defining characters are:
very poorly developed glomerulus
complete dorsal septum of collar
absence of lacunae or lumen in the collar cord absence of dorsal roots in the collar
no anterior neuropore, but the posterior neuropore is present only the primary lateral gonads present
Glossobalanus hartmanae n. sp. ( Figs 1 View FIGURE 1 , 3 View FIGURE 3 )
Etymology. The name honors Dr. Olga Hartman of the University of Southern California, long a major contributor to systematic and zoogeographic invertebrate zoology.
Material examined. Holotype: USNM 71750 (T.H. Bullock accession no. 206-1), comprising 12 slides.
Description. Whole animal a pale creamy white except in hepatic region, which is dark green-brown, lighter at each end. Overall length of one complete specimen 23–32 mm in medium relaxation to fair distension and 45 mm maximally extended; in the latter state, proboscis is 3.5 mm long, collar 3.5 mm, branchial region 5.5 mm, genital region 8 mm and especially distensible relative to other parts, hepatic region 4 mm in its sharply pigmented length and posthepatic abdomen about 14 mm. Genital wings not conspicuous, especially in branchial region. About 24 external hepatic saccules visible on each side externally ( Fig. 1 View FIGURE 1 A). (Data for colour and length of live worm taken from collection cards made by T.H. Bullock in 1938.)
Epidermal epithelium of proboscis not very thick. Circular-muscle-fiber layer rather conspicuous, slightly thicker than nerve-fiber layer; longitudinal muscle fibers arranged in radial bundles, leaving a quite spacious coelom ( Fig. 3 View FIGURE 3 A). Ventral septum extends nearly to tip of stomochord but not reaching ventral epidermis. Cardiac vesicle extending to tip of stomochord. Two halves of glomerulus rather small, confined to sides of junction between stomochord and cardiac vesicle; confluent anteriorly over tip of stomochord. Right and left dorsal proboscis canals present but narrow, opening together via single median proboscis pore. Stomochordal lumen rather narrow near anterior extremity but becoming quite marked about middle region. Stomochord with small ventrolateral pouches in communication with primary lumen ( Fig. 3 View FIGURE 3 B). Skeleton with rather short keel anteroposteriorly, blunt, not deep dorsoventrally, stopping short of posterior end of peduncle ( Fig. 3 View FIGURE 3 C).
Dorsal septum of collar commencing at first dorsal root, which forms anterior margin of septum; ventral septum confined to posterior fourth or fifth of collar. Midventral vascular plexus present throughout collar ( Fig. 3 View FIGURE 3 D). Collar nerve cord only with lacunae, no central canal. Three dorsal nerve roots present ( Fig. 3 View FIGURE 3 E). Skeletal cornua extending only half way through collar. Collar canals comprising short tubes with deep median dorsal infolding ( Fig. 3 View FIGURE 3 E). Peribuccal cavities extending to proboscis pore, confluent at their anterior extremity. Peripharyngeal cavities extending to level where stomochord opens into buccal cavity.
Gill pouches occupying dorsal half of gut in branchial region. Outer epithelium of gill and tongue bars extremely plicate, appearing more or less like a glomerulus in section ( Fig. 3 View FIGURE 3 F) but nuclei forming a single layer in epithelium itself. Gonads commencing immediately behind collar; only lateral primary gonads present in branchial region ( Fig. 3 View FIGURE 3 F). Eight or nine synapticula present. Genital ridges so poorly developed as to be inconspicuous. Anteriorly, lateral septum stops short of branchial region, extending at most to penultimate gill aperture. With appearance of lateral septum median gonads also appear ( Fig. 3 View FIGURE 3 G), these latter appearing to be more lobed than lateral gonads. Gonads extending to the commencement of hepatic region, appearing beside first one or two hepatic caeca. A short postbranchial canal present, displaced to right; abdominal ciliated groove present only on right side, commencing about middle of hepatic region. Lateral septum ceasing in anteriormost part of hepatic region.
Distribution. Five fragments including one anterior end were collected by Olga Hartman in March, 1938 at Spindrift (south end of Scripps Beach), La Jolla, California (32°51' N, 117°16' W) in crevices in shale rock. One complete specimen was collected by T.H. Bullock at the same location in December 1938.
Remarks. The description does not answer to that of any known species of Glossobalanus . Certain characters that are common to several other species of the genus are also present here, e.g. the anterior extent of the dorsal septum in the collar only to the first dorsal root. Like G. ruficollis , the present species has almost no genital ridges. Like G. berkeleyi , the stomochord has small ventrolateral pouches in communication with its primary lumen. But for these resemblances, the present form has no closer relationship with any known species of Glossobalanus . The defining characters of Glossobalanus hartmanae are listed below:
right and left dorsal proboscis canals open by a single median proboscis pore well developed midventral vascular plexus in collar
epithelium of the gill and tongue bars is extremely plicate
abdominal ciliated groove is present only on the right side
Glossobalanus barnharti n. sp. ( Figs 1 View FIGURE 1 , 4 View FIGURE 4 )
Etymology. The name honors Dr. Percy S. Barnhart, long-time curator of the Scripps Institution of Oceanography.
Material examined. Holotype: USNM 71749 (T.H. Bullock accession no. 207-1), comprising 29 slides.
Description. Proboscis twice as long as its base width. Collar broader than long, with shallow groove ringing its middle. Genital ridges beginning immediately behind collar. Branchiogenital region as in G. m i n u t u s ( Fig. 1 View FIGURE 1 C). Circular-muscle-fiber layer of proboscis c. 1.5 times thickness of the nerve-fiber layer; longitudinal muscle fibers arranged in massive radial groups ( Fig. 4 View FIGURE 4 A). Ventral septum extending nearly to tip of stomochord. Cardiac vesicle nearly coextensive with stomochord anteriorly. Right and left halves of glomerulus confluent at anterior extremity. Dorsal glomerulus small. Stomochordal lumen narrow, well defined to tip. Forepart of stomochord flattened, watchglass-like in transverse sections ( Fig. 4 View FIGURE 4 B). Stomochord with single midventral blind pouch ( Fig. 4 View FIGURE 4 C). Only left dorsal proboscis coelom opens to exterior by median dorsal proboscis pore, with spacious (bulbous) medially placed proboscis canal (vesicle). Anteriorly, body and keel of skeleton parted by invasion of coelomic epithelium, forming a spacious cavity that narrows posteriorly, stopping about level with proboscis pore. From here, posteriorly in peduncle, keel is rather deep and narrow ( Fig. 4 View FIGURE 4 D); further posteriorly it is shortened dorsoventrally, but extends some distance into collar region.
Dorsal septum of collar extending anteriorly to first dorsal root; ventral septum absent. Midventral vascular plexus of collar poorly developed ( Fig. 4 View FIGURE 4 E). Cornua extending half way through collar, taking sharp turn ventrally, ending about midway on lateral walls of buccal cavity. Collar nerve cord rather flattened, lateral margins thicker than rest. No axial canal, only some large lacunae. Anterior neuropore present. Eight or nine dorsal roots ( Fig. 4 View FIGURE 4 F). Perihaemal cavities extending to proboscis pore, confluent at their anterior extremity. Peribuccal cavities extending to about level of origin of skeletal cornua. Collar canals with deep dorsal fold.
Gonads commencing immediately behind collar. Dorsal pharynx larger than ventral digestive pharynx ( Fig. 4 View FIGURE 4 G). Lateral septum extending anteriorly to some distance into posterior part of branchial region. Lateral septum and medial gonads present. Presence of post-branchial canal not determined. Gonads continuing well into intestinal region ( Fig. 4 View FIGURE 4 H).
Distribution. Two specimens, one apparently complete, were taken by P.S. Barnhart (his acc. No. 1195) from the intertidal zone of the protected outer coast at Bird Rock, La Jolla, California (32°49' N, 117°14' W), in June 1921.
Remarks. It has already been stated above that the form under consideration resembles to some extent G. minutus in its external appearance. But in its internal anatomy it does not quite resemble that species. The two agree only in a few specific characters such as the forward extension of the proboscis ventral septum, the presence of a dorsal glomerulus and the absence of the ventral septum in the collar. The present species appears anatomically to be more closely related to G. sarniensis than to any other species of the genus. Thus these two have the following characters in common: connection of the left dorsal proboscis coelom with a large bulbous, median proboscis canal; continuous lumen in stomochord; cardiac vesicle anteriorly coextensive with stomochord; large keel and the separation of the keel and the body in the anterior part of the skeleton by a coelomic invasion. They differ in many more characters.
In external appearance G. barnharti differs from G. sarniensis in the shape of the proboscis and the collar and their relative sizes, in the clear-cut demarcation of the collar from the trunk, in the shape and appearance of the branchiogenital region and in the less-developed genital ridges, which are like alae in G. sarniensis . In internal anatomy, G. barnharti differs from G. sarniensis in the following: the circular-muscle layer of the proboscis is much thicker in G. barnharti ; in the possession of a small dorsal glomerulus, much narrower stomochordal lumen and flattened forepart of stomochord; middorsal proboscis pore; extension of the skeletal keel into the collar region, absence of ventral septum in collar, absence of continuous canal in the collar nerve cord, many more dorsal roots, absence of posterior neuropore, and in the position of the gonads.
The above facts show that the present species does not resemble sufficiently well either G. minutus or G. sarniensis for it to be included under those species. Still less does it resemble any of the other species of the genus. The defining characters of Glossobalanus barnharti are:
flattened forepart of stomochord
a single midventral blind pouch to the stomochord peduncle skeletal keel is deep and narrow, extending well into collar collar nerve cord is flattened
eight or nine dorsal roots in collar
Discussion
On the west coast of North America, the genus Glossobalanus has been taken once in the Salish Sea at Nanaimo, British Columbia (Willey 1931), once in Coos Bay, Oregon and three times in La Jolla, California, representing four different species. It is likely to turn up anywhere. Probably the ‘ptychoderids’ reported by Woodwick (1955), in three dredge samples at 40–90 m depth from San Pedro Basin, belong to this genus. The habitats include both sand flats and rocky rubble on the outer coast. For a detailed discussion of the distribution of North American acorn worms, including the new species described here, see Cameron et al. (2010).
Dichotomous keys to the genera of the enteropneust families Harrimaniidae (Deland et al. 2010) and Spengelidae ( Cameron and Perez, 2012) have been developed. The deep-sea family Torquaratoridae consists of five well-supported clades (Osborn et al. 2012), and the corresponding morphological descriptions are presently being assembled in the laboratory of professor Nicholas Holland (Scripps Institute of Oceanography). Here we provide a taxonomic key to the family Ptychoderidae .
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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