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Murphydoris polkadotsa

Species Profile

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Murphydoris polkadotsa

Author: Paz-Sedano, Cobb, Gosliner & Pola, 2024

Order: Nudibranchia  Family: Goniodorididae

Maximum Size: 5 mm

Sightings: Sunshine Coast

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Murphydoris polkadotsa Paz-Sedano, Cobb, Gosliner & Pola, 2024

Previously known on this site as Goniodoridella sp. 03 – Changed to Murphydoris sp. 03 March, 2022.
Previously known on this site as Murphydoris sp. 03 – Changed to Murphydoris polkadotsa 03 May, 2024.

CLARIFICATION ABOUT THE DISCOVERY AND PREVALENCE OF THIS SPECIES
We believe that Terry Farr and myself were the first to record this species, anywhere, (undescribed at the time) back on 24th March 2014 at the La Balsa Park dive site Mooloolah River, Sunshine Coast of Queensland, Australia. The species is small and very rarely sighted and only recorded from the Mooloolah River.

Murphydoris polkadotsa is a small species of phanerobranch nudibranch up to 5 mm in length. The edge of the notum is reduced and somewhat ragged or bluntly serrated, but without distinct papillae. There are large extra-branchial processes, one each side of the gill. These have a narrow stalk but an enlarged bulbous tip. The authors (Paz-Sedano et al., 2024) offer the suggestion: “… resemble papilla on each side of body, likely modified gill branches.” The non-retractile rhinophores are relatively large for the animal’s size, smooth and without sheaths, however the notal edge rises lateral and anterior to each rhinophore in the manner of a half cup. The notum is flat and narrows gradually, posterior to the gill, into a tapered tail.

The body presents with a translucent layer beneath which, much is covered by opaque white pigment. The notum and sides of the body exhibit many medium-sized brown, almost circular spots. Often these are arranged into two groups, one posterior to the rhinophores and another around the gill and extra-branchial processes. The rhinophores carry white pigment with yellow tips and often brown spots on their bases. The extra-branchial processes are translucent with white pigment internally and yellow tips, sometimes with brown spots. The tail carries a yellow tip and the anterior margin of the body in the oral region has a transverse yellow bar. The ventral surface of the foot is translucent white.

Murphydoris polkadotsa cannot be confused with any other species of Goniodorididae, the bulbous tips of the two extra-branchial processes and the circular brown spots being characteristic.

Distribution: Thus far, we and others have only reported it from the Mooloolah River on the Sunshine Coast of Queensland, Australia

Murphydoris is a genus of Goniodorididae.
The genus was erected in 1991 at the time of the single species description of Murphydoris singaporensis. Apart from Swennen & Buatip, 2012 further research on the genus has been lacking until Paz-Sedano et al, 2021 undertook a review of the morphological characteristics of the Gonidorididae family followed by Paz-Sedano et al, 2022 who described four new species of Murphydoris. All four of those new species, or at least considered variations thereof, have been recorded by us on the Sunshine Coast, Queensland, Australia. At the time of original recording those four were placed as undescribed species in the Goniodoridella genus due to (what are now viewed as) superficial similarities.

To summarise the external features – Murphydoris shares non-lamellate rhinophores with Goniodoridella, but is unique among goniodorids in lacking peri-anal ctenidia or gills. That means it does not have true gills around the anus. Instead it has some appendages at the termination of the mantle notal edge on each side. These may be homologous to, or at least perform like, true gills, and acting as such are not classed as papillae. Murphydoris lacks lateral and dorsal papillae.

It is these three characteristics – smooth rhinophores, a lack of lateral and dorsal papillae, and lack of peri-anal gills, that help to separate Murphydoris from the other genera of the Goniodorididae family.

David A. Mullins – March 2022 (Revised May 2024)

References:
– Baba, K. (1960). The genera Okenia, Goniodoridella and Goniodoris from Japan (Nudibranchia-Goniodorididae). Publications of the Seto Marine Biological Laboratory, 8(1), 79–83.

– Sigurdsson, J. B. (1991). A nudibranch, Murphydoris singaporensis, new genus and species, from Singapore mangroves (Mollusca: Opisthobranchia: Goniodorididae). Raffles Bulletin of Zoology, 39, 259–263.

– Swennen, C., & Buatip, S. (2012). Murphydoris singaporensis (Gastropoda: Nudibranchia: Goniodorididae) found in Thailand; with external and  first internal description of the specimens. Strombus, 19(1–2), 9–14.

– Paz-Sedano, S., Díaz-Agras, G., Gosliner, T. M. & Pola, M. (Online 2021). Revealing morphological characteristics of Goniodorididae genera (Mollusca: Nudibranchia). Organisms Biodiversity and Evolutionary Research. (2022) 22:93–116.

– Paz-Sedano, S., Smirnoff, D., Candas, M.,  Gosliner, T. M. & Pola, M., (2022). Rediscovering the overlooked genus Murphydoris (Nudibranchia: Goniodorididae): the first phylogeny and addition of four new species. Zoological Journal of the Linnean Society, 2022, XX, 1–20

– Paz-Sedano, S., Cobb, G., Gosliner, T. M. & Pola, M. (2024). Filling gaps in the knowledge of Goniodorididae taxa (Mollusca, Gastropoda, Nudibranchia) with description of seven new species. Zootaxa. 5443(4): 523-547.

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