Cyerce cristallina

Cyerce cristallina (Trinchese, 1881)

• Cyerce iheringi Pelseneer, 1892
• Lobiancoia cristallina Trinchese, 1881 (original)
• Lobifera cristallina (Portmann, 1958)

Description
It usually has a maximum length of about 35mm (although there are some reports of 50mm specimens) with a translucent cream colored body, that can be white (e.g. in some Atlantic specimens) or even more or less dark brown (in juveniles), with reddish brown spots (brightest in juveniles) arranged in a characteristic way. Particularly striking are the marks on the head, forming a shape like glasses around the eyes (which are evident at the top, against the cream-colored background of the body), a dark middorsal line covering the pericardial prominence and the reddish brown rim in the terminal part of each cerata. The cerata are leaf shaped, long and flat, with reddish brown pigment forming a characteristic oval pattern on their end and an elongated stain on the mesial side. In addition to the terminal reddish-brown spots there is a white border on each side of the red central mark. The flattened surface of the cerata is dotted with yellowish-white marks. Smaller cerata are located to the front of the animal while the older, longest ones are located in the middle and to the rear. The cerata lack any lobes of the digestive gland inside. There are three pairs of tentacles on the head (the rhinophores appear divided almost to the base and, therefore, there are two pairs) that are significantly rolled. Rhinophoral upper tentacles are reddish-brown, but the lower ones and the oral tentacles are cream colored, like the anterior margin of the foot. The anal papilla is colored bright cream and is located on the back, right ahead the pericardium, a little to the right of the midplane. Ventrally, the sole of the cream colored foot has a transversal mesopodial slot at the end of the first third of the body. The anterior margin of the foot is bilabiate, while its rear end is pointed. When the animal is at rest, the foot is almost hidden by the abundant cerata. Some descriptions mention a olive green band along the body, apparently related to the content of the digestive system, that would be visible by transparency.

Biology
It is an herbivorous species that feeds on algae. Spawn consists in a flat band arranged spirally with white eggs of 0.06 mm diameter. If the animal feels threatened it can discard some cerata that will move independently to distract the predator’s attention, allowing the animal to escape, while the defensive glands of each cerata (white-yellowish spots decorating it, whose number and size seems to depend on the life cycle of the animal) secrete a predator deterrent substance. The cerata can fully regenerate within a week. Thompson (1977) described four related species in Jamaica (Cyerce cristallina, Cyerce edmundsi, Cyerce antillensis and Polybranchia viridis) of which he mentioned they could be easily distinguished by the naked eye: “Polybranchia viridis has tuberculate papillae, while those of the other three species of Cyerce lack tubercles. Cyerce edmundsi has pearl-like swellimg along the free outer edge of the cerata, lacking in the other two species. Cyerce cristallina has crimson markings on a white background, while Cyerce antillensis is predominantly drab brown in colour”.

Etymology

• Cyerce. Apparently of mythologic origin. Bergh (the autor naming this genus) created a big number of genuses with mythologic consonances but not always linked to historic mythology.
• Cristallina. From Latin “crystallinus”, crystalline, with crystal properties.

Distribution
Cyerce cristallina was originally described in the Mediterranean, where it has been found both in the eastern and western basins. It has also been cited in the Atlantic. There are few reports of this species because it is highly cryptic on the environment it lives on: shallow waters with algal growths (Dictyopteris) and under rocks.

Known georeferenced records of the species: Cyerce cristallina
Sources:
: OBIS : GROC 2010-2011 : Enric Madrenas : João Pedro Silva : Bernard Picton : GBIF.ORG	: OPK : VIMAR : Manuel Ballesteros. : M@re Nostrum : Altres fonts : Marine Regions

Abundance

Western Mediterranean:	★☆☆☆☆
Eastern Mediterranean:	★☆☆☆☆
Atlantic Ocean:	★☆☆☆☆