Author: Fahey & Gosliner, 2004

Order: Nudibranchia  Family: Aegiridae

Maximum Size: 25 mm

Sightings: Sunshine Coast

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Aegires flores Fahey & Gosliner, 2004

In 2004 Fahey & Gosliner, along with a phylogenetic analysis of the Aegiridae family, described 8 new species of Aegires including our current subject Aegires flores.

Aegires flores is a stunning nudibranch when recorded under favourable lighting. One of the small Aegires species, to 25 mm, the shape of the body is elongate, rounded anteriorly and at the tail extremity; high and rounded in profile but highest mid-dorsum at the gills. The dorsum is entirely covered with raised tubercles mostly flat-topped and circular but some rounded. Spicules can be seen protruding from the top of most tubercles. The rhinophore pockets are raised, the edges bearing up to five large raised flat-topped protective tubercles. The rhinophores are smooth, tapering to a point and able to retract into the pocket. The small tripinnate gills are situated halfway along the dorsum at its highest point. They are protected by a circle of approximately 12 large upright paddle-shaped tubercles in the manner of a crown or flower petals (hence the chosen specific epithet – flores – Latin for blossom). The gills are contractile but cannot retract into a pocket – making it a phanerobranch nudibranch.

This variation in size of tubercles, where the protective ring of tubercles around the rhinophores and gills are of larger size than those over the remainder of the notum, is unique in the Aegiridae.

The colouration of Aegires flores is variable from pale to dark. The background colour is white to pale cream, in some a darker yellow. The colour variations appear to derive from the presence and concentration of small dark spots or even their absence and also the colour of the tubercles. The colour may be evenly distributed over the entire dorsum or as random patches of varying size. In some the tubercles are translucent white with just a spot of orange in the centre of the flat top, the tops of the gill and rhinophore protective tubercles being a pale yellow. In others the tubercles are a dark yellow with a lighter central patch to the flat tops, the larger protective tubercles matching. The rhinophores are a translucent white sometimes with a tint of yellow. The gills are also translucent white sometimes with black flecks. The ventral surface of the foot is white.

A report that all of the specimens of Aegires flores recorded from Sunshine Coast, Queensland waters are of a pale form, is incorrect.

The diet of Aegires flores is calcareous sponges as with all the Aegiridae species. Of the phanerobranchs only Aegiridae and Hexabranchidae are spongivores. The phanerobranchs however are not considered a natural grouping and research continues into their relationships.

The spawn is white and laid as an upright coil, on edge, of two to three whorls.

Whilst not a commonly encountered species it is nevertheless widespread in the Western Pacific, from the Marshall Islands across to Japan, down through the Philippines, Indonesia, Papua New Guinea to the sub-tropical coast of Eastern Australia.

David A. Mullins – August 2021

References:

– Fahey, S. J. & Gosliner, T. M. (2004). A phylogenetic analysis of the Aegiridae Fischer, 1883 (Mollusca, Nudibranchia, Phanerobranchia) with descriptions of eight new species and a reassessment of phanerobranch relationships. Proceedings of the California Academy of Sciences, 55, 613.

– Fahey, S. Image by Gosliner, T. (2006). Opisthobranch of the Week, Week: 499. Mike Miller’s Slug Site. Available at: http://slugsite.us/bow/nudwk499.htm

– Gosliner, T. M., Valdés, Á. & Behrens, D. W. (2018). Nudibranch and Sea Slug Identification: Indo-Pacific – 2nd Ed. New World Publications, Jacksonville, Florida.