Nudi Pixel: Nudibranchs and Sea Slugs Identification with Photographs

Phyllidia varicosa

Photographed by: Ria Qorina Lubis

Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Opisthobranchia
Order:	Nudibranchia
Suborder:	Doridina
Family:	Phyllidiidae
Species:	Phyllidia varicosa

This appears to be a juvenile Phyllidia varicosa, very similar to one I have from the Red Sea. It doesn't have the bar between the rhinophores of Phyllidia alyta, with which it might be confused. Unless there is a photo of the ventral side, we can never be certain!

With lines of orange-tipped tubercles and black lines in-between. This is one of the interesting variations where there is a transverse black line behind the rhinophores.

This identification would need to be checked by turning the specimen over to check it has a black stripe on the foot sole. Phyllidia varicosa is certainly known to be common in Hawaii.

I have seen a few specimens with that transverse black line anteriorly, like Phyllidia elegans. Very odd. But usually with four smooth black longitudinal lines lining three rows of orange tipped tubercles.

This individual is characteristic of Indian Ocean populations of this species which have 3 parallel longitudinal rows of pustules on the centre of the mantle. In contrast, Pacific Ocean populations of this species have only 1 definite row mid-centrally.

This image shows the dorsal location of the anal pore nicely as a black dot in the midline towards the rear.

This individual has sustained serious damage on the centre of its notum, this disrupting the normally straight rows of pustules.

A typical individual.

The dorsal tubercles are arranged in definite longitudinal ridges, which is typical of Phyllidia varicosa. They would not be arranged so regularly like this in Phyllidia coelestis and also there are not enough small pustules close to the edge of the mantle to be Phyllidia coelestis.

An unusual individual in which the pustules on the mantle are not clearly grouped into three longitudinal rows. But this could be an artefact of its posture. There is a single large pustule immediately behind each rhinophore (called a rhinotubercle). There is a series of prominent black longitudinal dashes forming a stripe on the foot sole.

Locality:

• Indonesia
  • Bali (8) Feb, Mar, May, Oct
  • Pulau Seribu (4) Apr, May
  • Raja Ampat (2) Feb
  • Derawan (2) May
  • Bunaken (2) Sep
  • Lembeh (2) Jan, Sep
  • Manado (2) Oct, Dec
  • Ambon (1) Dec
  • North Sulawesi (1) Apr
• USA
  • Oahu, Hawaii (3) Mar, Sep
• Malaysia
  • Tioman (2) Oct
  • Mabul (2) Jul, Aug
  • Aur - Dayang (1) Apr
  • Redang (1) May
  • Malaysia (1) Sep
  • Tenggol (1) Sep
  • Lankayan (1)
• Myanmar
  • Myanmar (2) Feb
• Mozambique
  • Ponta Malongane (2) Dec
  • Inhambane (1) May
• Egypt
  • Red Sea (2)
• Maldives
  • South Ari Atoll (2) Aug
  • Maldives (1)
• Sri Lanka
  • Negombo (2) Jan, Mar
  • Weligama (1) Apr
• Solomon Islands
  • Solomon Islands (2) Feb, Jul
• Australia
  • Queensland (1) Oct
• Japan
  • Okinawa (1)
• Taiwan
  • Long Dong (1)
  • Green Island (1)
  • Orchid Island (1)
• South Africa
  • Sodwana Bay (1) Aug
• Thailand
  • Similan Islands (1) Nov
• PNG
  • PNG (1)
• Vietnam
  • Vietnam (1)

 

Pictures of Phyllidia varicosa

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(60 photos)

Similar Species

Author: Nila Murti

To untrained eye, Phyllidia coelestis can easily be mistaken for Phyllidia varicosa and vice versa. Understandable, as these two posses very similar basic form, coloration and pattern. Both have tubercles with blue bases and yellow caps.

To differentiate the two look at the dorsal pattern. If the nudibranch has a median ridge it's a Phyllidia varicosa. If it doesn't have a median ridge and the ridge forms a Y shape arrangement instead, it's a Phyllidia coelestis.

Phyllidia coelestis also shows a broader mantle margin with smaller tubercles that has no yellow caps.

And also juvenile form of sea cucumber, Pearsonothuria graffei, mimic Phyllidia varicosa

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