Sadleriana baoarica Boeters, 1989
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publication ID |
https://doi.org/10.5281/zenodo.16851127 |
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persistent identifier |
https://treatment.plazi.org/id/A642A030-FFCE-5D7A-34E6-FFE7996DFB2B |
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treatment provided by |
Felipe |
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scientific name |
Sadleriana baoarica Boeters, 1989 |
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Sadleriana baoarica Boeters, 1989
Holotype: HYD1008, stored at the Senckenberg Museum of Natural History , Frankfurt ( Figs 1A- C View Fig ). – Material examined: 5 specimens ( ZSM Mol 20131107- 2013111), collected at the type locality (Brunnbach, Munich). Embedded in epoxy resin, 4 of them sectioned. Several further specimens (two lots: ZSM Mol 20131112, 20131113).
Natural habitat
In its natural habitat ( Fig. 1D View Fig ), S. baoarica is found abundantly in shallow water (10-40 cm), dwelling actively at day on rocks and driftwood that are covered by a biofilm of green algae and diatoms ( Fig. 1E View Fig ). Male and female specimens of Sadleriana baoarica occur mixed with individuals of another hydrobiid species (here tentatively identified as Bythiospeum sp. ). Specimens of S. baoarica are most abundant close to the Brunnbach spring.
External morphology
Sadleriana baoarica has a thick and brown shell between 3 to 4 mm in height and 3 to 3.5 mm in width, with 3.5 or 4 rapidly increasing whorls. The umbilicus is open and slotted. In most specimens the shell is covered in green algae ( Fig. 1F- I View Fig ). A corneous, reddish-brown operculum is attached to the footend’ s upper side measuring 1.1 to 1.7 mm ( Figs 3B,G View Fig ; op). The soft body is black, except for the foot sole and the tentacle bases. The body is subdivided into a dextrally coiled visceral sac, which lies inside the shell curling up to the apex, and a broad muscular head-foot. The foot is broadened at the front and contains a well-developed foot gland (propodial gland), which is 0.6 mm width and 0.5 mm height ( Figs 2F View Fig , 3A,C,G View Fig ; fg, fgo). The head is clearly differentiated from the foot and possesses a pair of thin tentacles (0.6 mm long), which cannot be retracted. Eyes are located at the outer side of each tentacle base ( Figs 2G View Fig , 3A,C,D View Fig ; ey, tn). Here there is also a cushion-like batch of vacuolated cells. The snout is long, flexible, and protrusible ( Figs 3C,D View Fig ; sn).
Mantle cavity and pallial organs
The mantle cavity and pallial organs were reconstructed from the male specimen (9W2). The mantle cavity fills nearly half of the first whorl and then narrows to its rear parts increasingly ( Figs 2B View Fig , 3D View Fig ; mc). On its left side, the ctenidium is formed by 8 leaflets each of about 0.2 mm length ( Figs 2A,B View Fig , 3A- C View Fig ; ct, ctf). Behind the ctenidium, there is a voluminous semicircular mantle gland (length: 0.75 mm, height: 0.2 mm) ( Figs 2B,D View Fig , 3A,C,D View Fig ; mg). Histologically, the gland consists of a strip of particularly tall epidermal cells that are stained in a very dark blue ( Fig. 2B,D View Fig ). Two distinct body openings lead into the mantle cavity’ s right part: the anus opens into the right corner of the mantle cavity ( Figs 2B View Fig , 3A View Fig ; an); in males, the genital opening is located on the right side of the head-foot. The osphradium is a crescent-shaped, ciliated groove with tall yet narrow epithelial cells situated on the anterior left side of the mantle cavity roof, anterior to the gill; there is an oval ganglion just below the epithelium ( Fig. 2C View Fig ; osp and osg). The pericardial complex is located posteriorly, dorsally and to the left.
Circulatory and excretory systems
The pericardial complex comprises the main organs of the circulatory and excretory systems and is located at the posterior left of the mantle cavity, near the mantle gland ( Fig. 3E,F View Fig ). The kidney measures 1.8 mm in length and 0.43 mm in width. It is characterized by a vacuolated and unstained epithelium ( Fig. 2L View Fig ). Superior to the kidney there is a nephridial ‘gland’, a mass that contains loosely organized, irregular and unstained cells with darker blue nuclei ( Fig. 2M View Fig ); the part of the kidney in contact with this structure is thin and not vacuolated, forming short, apparently blind-ending ducts that project into the nephridial gland ( Fig. 2M View Fig ; nch and ng). On its posterior side, the kidney is attached to a thin-walled pericardium, which surrounds a twochambered heart: a thicker-walled ventricle and an auricle ( Fig. 3E,F View Fig ).
Digestive system
The digestive system consists of a short pharynx, followed by the short esophagus leading into the stomach, which is connected to a voluminous digestive gland. The intestine runs from the stomach to the mantle cavity’s right side.
The mouth opening lies medially on the tip of the snout and leads into a wide pharynx. The pharynx contains a pair of small chitinous jaws, which are fused dorsally and located just behind the mouth opening, and two pads of epithelial single-celled glands in the posterior lower part. The radula ( Figs 2I View Fig , 4B View Fig ) is quite long (about 1 mm) and shaped like a question mark. It extends through much of the snail’ s headfoot and is equipped with roughly 60 rows of teeth which are stained in a dark blue. The radula is bedded on two lower cartilaginous pillows and is topped by a smaller upper cartilage, all characterized by voluminous unstained cells with big and well-apparent nuclei and minute darker granules ( Figs 2H View Fig , 4B View Fig ). Two long (ca. 0.8 mm), tubelike salivary glands lie on the pharynx and open nearby the mouth opening. Histologically, they are glandular with numerous small vesicles and stained blue. Centrally, the salivary glands have a narrow lumen ( Fig. 4A,C,E View Fig ). The pharynx narrows to a ciliated oesophagus leading into the stomach. The stomach wall is muscular and thick (66 µm). The stomach is separated into a smaller, ciliated, upper part (style sac) and a bigger lower bag (gastric chamber) ( Fig. 4A,C- E View Fig ). The latter is equipped with a light blue-stained, angular and cuticular shield that carries a strongly elevated ridge ( Figs 2L View Fig , 4D View Fig ; gs). The stomach’s interior is voluminous and shows some amorphous remains of food, including abundant shells of diatoms ( Fig. 2K,L View Fig ). Attached to the stomach, the big digestive gland extends as a spiral to the apex. The digestive gland cells are stained bright with large vacuoles; the gland itself has thick walls and a big lumen which distinguish it from the finer structured gonad, with which it is interlaced ( Figs 2J View Fig , 5A- C View Fig ). The ciliated intestine leaves the stomach centrally and features a single loop that is about 2.5 mm long and quite thick (0.2 mm). The loop is thick-walled and muscular, and at some parts bulging, with irregular surface, due to food pellets inside. Narrowing slightly, it opens into the right hand side of the mantle cavity (anus) ( Figs 3A,B View Fig , 5A- C View Fig ).
Reproductive system
The male reproductive system comprises a gonad, a prostate and a penis ( Fig. 5A- C View Fig ). The gonad is slightly coiled, spacious, overlaying the digestive gland. It is histologically characterized by a finely dotted appearance, and moderately stained ( Fig. 2J View Fig ). Emerging from the gonad, a thin-walled proximal male gonoduct first forms an undulated ampulla (84 µm wide) and then a rather straight vas deferens portion, which leads into the posterior end of prostate. The prostate is kidney-shaped, measuring 0.49 mm in length and 0.23 mm in width ( Fig. 5A- C View Fig ). Its lumen is slightly stained, surrounded by a thick wall of blue stained cells. The distal vas deferens is a long, thin, and darkly staining tube (45 µm thick) opening at the tip of the penis ( Fig. 5B View Fig ). The penis is about 1 mm long, flat and tapering towards its tip. The outer surface is rough and covered by concentric and regular folds ( Fig. 5A- C View Fig ); the distalmost vas deferens is not demarcated externally (see Discussion). The female reproductive system is not described here, as examined individuals were immature, with indistinctly developed reproductive organs.
Central nervous system
The central nervous system consists of paired pedal and cerebropleural ganglia, and a smaller pair of buccal ganglia. The nerve-ring is circumoesophageal and epiathroid. The visceral loop is short, with three ganglia that are close together ( Figs 6A View Fig , 7 View Fig ): on the left and right, the respective sub- and supraesophageal ganglia are closely annexed anteriorly to the cerebropleural ganglia. The middle, visceral ganglion is situated slightly to the right. From the supraesophageal ganglion emerges a long connective that runs to the left, where it carries the osphradial ganglion ( Figs 6A View Fig , 7 View Fig ; but see Discussion). The osphradial ganglion carries two nerves, one of which runs to the osphradium, where it carries another, distal ganglion just below the osphradial epithelium ( Fig. 2C View Fig ). Histologically, the ganglia are characterized by distinct neurons in the periphery and lighter-stained nerve fibers in the centre.
The pedal ganglia are biggest (length: 0.44 mm, width: 0.23 mm) and interconnected by a single, short and thick (80 µm) commissure ( Figs 6A- C View Fig , 7 View Fig ). Each pedal ganglion bears three nerves, the two thick, anterior ones carry a small ganglion each (ca. 60 µm in diameter; Fig. 7 View Fig ). Attached to the upper, posterior surface of the pedal ganglia are the two statocysts (0.13 mm diameter; Fig. 6B View Fig ), with a single spherical statolith. The static nerve was not detected. The paired cerebropleural ganglia (length: 0.43 mm, width: 0.16 mm) are connected to each other via a long commissure (connective width: 60 µm), and to the pedal ganglia by two connectives per side, the cerebropedal and pleuropedal connectives ( Figs 6 View Fig , 7 View Fig ). Three nerves emerge from each cerebral ganglion ( Figs 6A,C View Fig , 7 View Fig ): nerve 1 (N1, 30 -35 µm thick) emerges anteroventrally and innervates the sides of the snout, nerve 2 (65 µm thick; a fused N2+N3, see Discussion) innervates the tentacle and the eye after splitting into three branches. The third nerve (N4, 30 µm thick) emerges at the base of N2 and also innervates the snout. Paired buccal ganglia (0.12 mm) are located in front of the cerebral ganglia and are connected to each cerebral ganglion by a single, short connective ( Figs 6A,C View Fig , 7 View Fig ); each buccal ganglion carries a nerve that runs to the sides of the pharynx ( Figs 6A View Fig , 7 View Fig ).
| ZSM |
Bavarian State Collection of Zoology |
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.