COMMENTS & OBSERVATIONS

A small amount of chop on the way out to Holbourne Island had us wondering if the weather forecast  was correct, but conditions continued to improve throughout the day and we had smooth seas by the time of our return trip. Our previous survey at this site had been exploratory and we began to search in earnest on these dives.

Our searching was so intensive that we almost missed the visit by an inquisitive Manta Ray that came in very close for a look to see what we were up to. However, the effort paid off and we were pleased to find 15 different species, some of which we had not previously recorded in Australia. Relevant species were the Phyllidiella zeylanica, Gymnodoris sp. 31, and Plakobranchus sp. 01. The number of Aegires gardineri sighted was impressive and two of these were extremely small and not noticed until we reviewed our photos (see bottom left in the photo below).

Taxonomic Diversity:
13 of the 15 species sighted were nudibranchs with 12 being dorids comprising 2 x phanerobranchs (non-retractile gill), 5 x porostomes (suctorial feeders – all of the Phyllidiidae family), 5 x cryptobranchs (retractable gill – all except one belonging to the Chromodorididae family) and 1 x cladobranchs comprising 1 x aeolid. 2 x sacoglossans round out the species numbers. If diet is considered then 11 of the 15 species sighted are spongivores.

Our Historical Data:
– We have now completed three surveys at this site since our first on 13/03/2023 and have recorded 20 species here.
– This was the first time we have recorded Favorinus mirabilis, Gymnodoris sp. 31, Phyllidiella zeylanica or Plakobranchus sp. 01 in Australia;
– This is the second occasion on which we have recorded Verconia sp. 07 in Australia. The first recording was at Terry’s Delight, Sunshine Coast on 27/7/18 when we placed the animal in the genus Thorunna. A review of the photos today, revealing significant mantle gland formations and the observation that it did not vibrate its gills when moving, have led us to believe that the genus Verconia is more appropriate. (We will have to wait until the animal is formally described to find out which is correct.)

Key to symbols
+++ New Species
+ First time sighted at Whitsundays
# Most commonly sighted at this site with %

TOTAL SPECIES SIGHTED: 15

DIVE IMAGES GALLERY

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