Trapania from India is not Trapania goslineri

March 15, 2010
From: Hans Bertsch

Note added 1 June 2010: This is probably T. toddi. see message #23677.

Concerning message #23291:

Dear Bill,
Greetings, amigo.
Regarding the posting on 3 March 2010, now titled, "Trapania goslineri from Ratnagiri, India," I would respectfully ask you to please change the title to: "Trapania sp. from Ratnagiri, India."

Most of us on this coast who have worked with Trapania goslineri do not consider his image from India to be of T. goslineri. Titleing it with the wrong species name introduces confusion into quotable sources, and erroneously reports a range extension that could then be misused in future reports.
There are obvious morphological and coloration features that distinguish his photographed specimen from the true tropical eastern Pacific T. goslineri. The burden of proof (dissections) is on sameness, so such an extension should not be promulgated. It strikes me there may be IP species that would be a far more reasonable identification.

Having written several comparative biogeographic papers over the years (e.g., Bertsch, 1979, 1991, 1993, 2009 [various], and in press), I am aware of the problems that such mislabeling can cause.

Thank you very much for your help.
Sincerely,
Hans

billr@seaslugforum.net

Bertsch, H., 2010 (Mar 15) Trapania from India is not Trapania goslineri. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/23350

Dear Hans,

It's good to hear from you. I know of no named Indo-West Pacific species with this colouration. Some years ago I used to consider the Eastern Pacific to be a separate zoogeographic zone so was unwilling to identify species from there with Indo-West Pacific animals. An example is the Porites-feeding aeolid Phestilla from western Panama which I named P. panamica to distinguish it from its IWP 'cousin' P. lugubris. I have discussed my reason in an earlier message [#13092] which was met with a deafening silence.

More recently there are a number of Indo-West Pacific species which have been accepted as members of the Eastern Pacific fauna by workers from that region.

For example Camacho-Garcia, Gosliner & Valdes (2005) list Aeolidiella indica, Aeolidiella alba, Lomanotus vermiformis, Stylocheilus striatus, Dolabrifera dolabrifera, Dolabella auricularia, Elysia pusilla, all Indo-West Pacific species, as being part of the tropical East Pacific fauna. I a sure all of these have been reported from the west coast of India.

This is not to say the Trapania in question must be Trapania goslineri or perhaps as I suggested T. darwini, but I don't think it totally out of the question. Re-reading the last paragraph of my comments in Vishal Bhave's message I think I have made it abundantly clear that the identification can only be tentative on present information.

Your concern about careless zoogeographers using data uncritically unfortunately applies to most 'listmakers' and unfortunately the web has given them free rein. I did consider removing Trapania goslineri from the title when I posted the message but I think it is a useful flag to draw users' attention to the record. I'll add a ? to the original message title and add a note referring to your concerns.

  • CAMACHO-GARCÍA, Y. E., T. M. GOSLINER, & Á. VALDÉS. 2005. Guía de campo de las babosas marinas del Pacifica este tropical / Field guide to the sea slugs of the tropical eastern Pacific. California Academy of Sciences, 129 pp.

Best wishes,
Bill Rudman

Rudman, W.B., 2010 (Mar 15). Comment on Trapania from India is not Trapania goslineri by Hans Bertsch. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/23350

Factsheet

Trapania toddi

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