Thomas Menut, Frankreich
Info
Idaliadoris depressa (Alder & Hancock, 1842)
Scientists weren't sure about this very flat and small slug and determined it to be Atalodoris, Doris, Knoutsodonta, and even Onchidoris. The currently valid name is Idaliadoris depressa.
The small body, maximum length 9 mm, has a recessed dome profile. The outline from above is an ellipse, evenly rounded at both ends. The colorless, almost transparent coat has very long, glittering, glass-like needles embedded in it. They are arranged transversely on the back between the rhinophores and gills.
Below the mantle, the orange-brown digestive gland and other white viscera are visible. Alder and Hancock (1845-55) stated that this was the only species of dorid in which they could see the internal eyes in adulthood, and they showed them in their picture, but the eyes were often hidden. The surface of the mantle is covered with inconspicuous, long, linear, colorless, transparent, soft tubercles. Small reddish, orange or purplish-brown spots are arranged on the mantle in about six longitudinal lines between the gills and rhinophores and about three concentric lines around the sides.
The rhinophores are white, sometimes faintly orange or yellowish, with up to ten obliquely inclined lamellae. The inconspicuous anal papilla is surrounded by a circle of up to twelve small, single-pinnate gills, which are so transparent that they are almost invisible except for a sometimes faint yellowish or pale orange hue.
If you lift the cloak from the front, you can see the orange mouth parts protruding from behind the veil.
Key identifying features of Idaliadoris depressa:
1: usual maximum length 9mm. Profile very depressed
2: The almost transparent, colorless coat has small, reddish-brown spots arranged in lines and visible, long, shiny needles
3: long, soft, non-spiny, transparent bumps on the mantle
4: Asymmetrical, orange-brown digestive gland extends forward to the left of the animal.
Idaliadoris depressa lives at low spring tide levels and sublittorally up to 15 m on hard ground, on or near its food, the bryozoan Schizomavella linearis, on the underside of stones. The spots on the mantle resemble those of bryozoans zooids.
The spawn is detected in September, for example in Great Britain. It is laid down as a thin pink line in a tight, neat spiral of about ten turns. The salmon-pink egg cells are arranged in twos or threes next to each other.
Note: Distribution beyond Great Britain, Ireland and the northern French coast is uncertain due to confusion with similar species in the Mediterranean and a large area of the Indo-Pacific. The small slug is often simply overlooked or confused.
There is a possibility of confusion with Atalodoris sparsa.
Synonymised names
Atalodoris depressa (Alder & Hancock, 1842) · unaccepted > superseded combination
Doris depressa Alder & Hancock, 1842 · unaccepted > superseded combination
Knoutsodonta depressa (Alder & Hancock, 1842) · unaccepted > superseded combination
Onchidoris depressa (Alder & Hancock, 1842) · unaccepted
Scientists weren't sure about this very flat and small slug and determined it to be Atalodoris, Doris, Knoutsodonta, and even Onchidoris. The currently valid name is Idaliadoris depressa.
The small body, maximum length 9 mm, has a recessed dome profile. The outline from above is an ellipse, evenly rounded at both ends. The colorless, almost transparent coat has very long, glittering, glass-like needles embedded in it. They are arranged transversely on the back between the rhinophores and gills.
Below the mantle, the orange-brown digestive gland and other white viscera are visible. Alder and Hancock (1845-55) stated that this was the only species of dorid in which they could see the internal eyes in adulthood, and they showed them in their picture, but the eyes were often hidden. The surface of the mantle is covered with inconspicuous, long, linear, colorless, transparent, soft tubercles. Small reddish, orange or purplish-brown spots are arranged on the mantle in about six longitudinal lines between the gills and rhinophores and about three concentric lines around the sides.
The rhinophores are white, sometimes faintly orange or yellowish, with up to ten obliquely inclined lamellae. The inconspicuous anal papilla is surrounded by a circle of up to twelve small, single-pinnate gills, which are so transparent that they are almost invisible except for a sometimes faint yellowish or pale orange hue.
If you lift the cloak from the front, you can see the orange mouth parts protruding from behind the veil.
Key identifying features of Idaliadoris depressa:
1: usual maximum length 9mm. Profile very depressed
2: The almost transparent, colorless coat has small, reddish-brown spots arranged in lines and visible, long, shiny needles
3: long, soft, non-spiny, transparent bumps on the mantle
4: Asymmetrical, orange-brown digestive gland extends forward to the left of the animal.
Idaliadoris depressa lives at low spring tide levels and sublittorally up to 15 m on hard ground, on or near its food, the bryozoan Schizomavella linearis, on the underside of stones. The spots on the mantle resemble those of bryozoans zooids.
The spawn is detected in September, for example in Great Britain. It is laid down as a thin pink line in a tight, neat spiral of about ten turns. The salmon-pink egg cells are arranged in twos or threes next to each other.
Note: Distribution beyond Great Britain, Ireland and the northern French coast is uncertain due to confusion with similar species in the Mediterranean and a large area of the Indo-Pacific. The small slug is often simply overlooked or confused.
There is a possibility of confusion with Atalodoris sparsa.
Synonymised names
Atalodoris depressa (Alder & Hancock, 1842) · unaccepted > superseded combination
Doris depressa Alder & Hancock, 1842 · unaccepted > superseded combination
Knoutsodonta depressa (Alder & Hancock, 1842) · unaccepted > superseded combination
Onchidoris depressa (Alder & Hancock, 1842) · unaccepted
