[Taxacom] abbreviation in authority citation

[Diana =?iso-8859-1?Q?Hern=E1ndez?=]

Dear all,
Does anybody know the meaning of "t.t" in the authority of a species?

An example could be a collembola 
species:  Proisotoma minuta (Tullberg, 1871, t.t.) B?rner, 1903
I would like to know what is it and if 
abbreviating the authorship which author could be excluded?

Thanks in advance




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Diana Hern?ndez Robles
Direcci?n T?cnica de An?lisis y Prioridades
CONABIO
Tel. +52 (55) 5004-5017
Fax +52 (55) 5004-4931
dhernand at xolo.conabio.gob.mx
www.conabio.gob.mx
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