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Crops > Plantation crops > Coconut & oil palm > Insects > Diocalandra taitensis, coconuts, Cook Islands

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Diocalandra taitensis, coconuts, Cook Islands

September 2013. A distinctively marked weevil from Cook Islands. What is it?

Later, the collector in Cook Islands wrote: I have Diocalandra taitense on our database based on a poor image of an
Auckland Museum specimen. I had looked at D. taitense on the web (such as )and at Zimmerman’s Figs. 31-34 and the species is shown with very indistinct markings – nothing like the contrasty distinctive markings of my specimen. Hence the enquiry. Looking again at Zimmerman, my specimen agrees with his female rostrum, but the setae on the pygidium do not form a medial crest, which probably shows my interpretation of the rostum is mistaken. I have the specimen if someone would like it in their collection. I assume the marking of the species are very variable.

Members thought it was Diocalandra taitensis; this species feeds on coconuts, the larvae boring in the husk and petiole of the fruit. It doesn’t appear to cause too many problems, but it may not have been studied much. Elwood Zimmerman has written about its identification and impact in his 1968 paper on the Rhynchophorinae of Polynesia. It is available online here:

Another expert on weevils commented:

  • It looks like Diocalandra taitensis, but the antennal clubs, eyes and pygidium are not quite clear in the photos to be sure. This is where the real differences from D. frumentilie, not in the colour pattern (the same occurs in D. frumenti). These structures should be checked to make sure it is D. taitensis(ideally also the genitalia).
  • The spelling of the species name has to be taitensis, not taitense, as the genus name Diocalandrais feminine in gender. This error seems to have started with Guérin-Méneville, when he described (illustrated) the species as Calandra taitense in 1833, but Zimmie didn’t correct it either in his 1968 paper or in the section on Diocalandrain his Australian WeevilsVol. III*.

It was mentioned that D. frumenti is in Samoa.

*More on this was given by Rolf Oberprieler, CSIRO, in response to a question whether Diocalandra taitenseor D. taitensisis correct. Since nobody has corrected Zimmerman in a publication, strictly speaking the use of taitenseshould remain until an official publication corrects the spelling?

I had a similar question yesterday but it didn’t go to all pestnetters. The issue isn’t whether someone has corrected Zimmie’s usage but which spelling is in accord with the International Code of Zoological Nomenclature. And that’s pretty straightforward in my book.

Guérin-Méneville described the species as Calandrataitenseon Plate 39 bis (dated Sept. 1933) and on p. 171 in the text (7 Sept. 1844) of his Iconographiedu Règne Animalbut in doing so violated the simple rule of Latin grammar (as of other gender-based languages) that nouns and their adjectives have to agree in gender – Calandrais feminine, the suffix –enseis neuter. Perhaps it was just a printer’s error. I haven’t gone through the 180 years of weevil literature since then in detail, but Gyllenhal (1838) placed the species in Sitophilus, which is masculine, and correctly changed the spelling of the species name to taitensis(-ensisis masculine and feminine). In their Catalogus Coleopterorumof 1872, Gemminger & von Harold also corrected it to Calandra taitensis, and in the later Junk/Schenkling Catalogus ColeopterorumCsiki (1936) listed it as Diocalandrataitensis, again grammatically correct. I don’t know how it was spelled when first put in Diocalandra(Faust didn’t include the species in this genus when he described it, in 1894), but presumably it was correctly spelled as taitensisuntil perhaps Zimmerman’s 1968 paper (which seems to have reintroduced the error).

But this bit of grammar and history aside, the ICZN in Art. 31.2. stipulates that adjectival species name have to agree in gender with the genus name with which they are combined, and in Art. 34.2. that their suffixes have to be changed when they are combined with a genus name of a different gender. Such changes are mandatory under the Code (Art. 34). So Calandrataitenseis an incorrect original spelling, and it has to be corrected to taitensiswhen the species is placed in a feminine genus (such as Calandraand Diocalandra) or in a masculine one (such asSitophilus), and it can only be taitensewhen combined with a genus name of neuter gender.

I know that some taxonomists (lepidopterists in particular) ignore these two articles, but that’s a contravention of the Code and not practiced in Coleoptera. Zimmie also didn’t do it, and he was certainly aware of this ICZN rule (and adhered to it) when he was working in Australia, but this may not have been the case earlier (e.g. in 1968). He may then simply have assumed that the original spelling is the correct one, and not checked either Latin gender suffixes (speakers of genderless languages such as English seem to struggle with the concept) or the ICZN. Whatever the reason, the spelling taitensewas both corrected long before Zimmie’s paper and it clearly contravenes the ICZN rules. We should not perpetuate this error!