<i>Andalucia</i> (n. gen.)—the Deepest Branch Within Jakobids (Jakobida; Excavata), Based on Morphological and Molecular Study of a New Flagellate from Soil

<jats:p><jats:bold>ABSTRACT. </jats:bold> A new heterotrophic flagellate (<jats:italic>Andalucia godoyi</jats:italic> n. gen. n. sp.) is described from soil. Earlier preliminary 18S rRNA analyses had indicated a relationship with the phylogenetically difficult‐to‐place jakobid <jats:italic>Jakoba incarcerata</jats:italic>. <jats:italic>Andalucia godoyi</jats:italic> is a small (3–5 μm) biflagellated cell with a ventral feeding groove. It has tubular mitochondrial cristae. There are two major microtubular roots (R1, R2) and a singlet root associated with basal body 1 (posterior). The microtubular root R1 is associated with non‐microtubular fibres “I,”“B,” and “A,” and divides in two parts, while R2 is associated with a “C” fibre. These structures support the anterior portion of the groove. Several features of <jats:italic>A. godoyi</jats:italic> are characteristic of jakobids: (i) there is a single dorsal vane on flagellum 2; (ii) the C fibre has the jakobid multilaminate substructure; (iii) the dorsal fan of microtubules originates in very close association with basal body 2; and (iv) there is no “R4” microtubular root associated with basal body 2. Morphological analyses incorporating the <jats:italic>A. godoyi</jats:italic> data strongly support the monophyly of all jakobids. Our 18S rRNA phylogenies place <jats:italic>A. godoyi</jats:italic> and <jats:italic>J. incarcerata</jats:italic> as a strong clade, which falls separately from other jakobids. Statistical tests do not reject jakobid monophyly, but a specific relationship between <jats:italic>Jakoba libera</jats:italic> and <jats:italic>J. incarcerata</jats:italic> and/or <jats:italic>A. godoyi</jats:italic> is rejected. Therefore, we have established a new genus <jats:italic>Andalucia</jats:italic> n. gen. with the type species <jats:italic>Andalucia godoyi</jats:italic> n. sp., and transfer <jats:italic>Jakoba incarcerata</jats:italic> to <jats:italic>Andalucia</jats:italic> as <jats:italic>Andalucia incarcerata</jats:italic> n. comb.</jats:p>