Vicinopone, Bolton & Fisher, 2012

Bolton, Barry & Fisher, Brian L., 2012, Taxonomy of the cerapachyine ant genera Simopone Forel, Vicinopone gen. n. and Tanipone gen. n. (Hymenoptera: Formicidae) 3283, Zootaxa 3283 (1), pp. 1-101 : 73-74

Comments on Vicinopone

The worker of the single small, yellow species included here was described in considerable detail by Brown (1975) as Simopone conciliatrix . He argued that the species exhibited a mixture of characters of several genus-rank taxa, but concluded that the “lack of spurs on the tibiae of the middle legs is considered here as definitive in placing the species in Simopone ”.

We are not convinced by the present investigation that the loss of mesotibial spurs represents a single evolutionary event, and most probably should not be considered as a synapomorphy of Simopone (sensu lato) and S. conciliatrix . In fact, the comparative analysis carried out here suggests a very different conclusion, as the loss of mesotibial spurs is just about the only derived feature that conciliatrix and the rest of Simopone have in common. The similar loss of mesotibial spurs in Tanipone , an otherwise very different taxon, only serves to reinforce the suspicion that spur loss is not synapomorphic but has merely been acquired by convergence in three separate lineages. Because of this, and in view of the differentiating characters listed below, conciliatrix is hereby removed from Simopone and transferred to its own monotypic genus, Vicinopone .

In major details of morphology, striking contrasts between Vicinopone and all species of Simopone include the following (the state considered apomorphic is italicised).

1 Palp formula is 3,2 in Vicinopone , as opposed to 6,4 or more rarely 5,3 in Simopone .

2 Antennae have 12 antennomeres in Vicinopone , as opposed to 11 antennomeres in Simopone .

3 Scape, when laid straight back, reaches the posterior margin of the eye in Vicinopone , as opposed to the anterior margin of the eye in Simopone (SI 57–67 in Vicinopone, SI 33–56 in Simopone ).

4 Ocelli are absent in Vicinopone , as opposed to present in Simopone .

5 Eyes are shifted very far forward in Vicinopone , as opposed to being near or behind the midlength in Simopone (EP 0.32–0.41 in Vicinopone, EP 0.68–1.91 in Simopone ).

6 A differentiated posterior (occipital) surface to the head occurs in Vicinopone , as opposed to the lack of such a surface in Simopone .

7 Pre-occipital carina (that extends down the posterolateral margin of the head and onto the ventral surface) runs right across the ventral surface to intersect the ventral midline in Vicinopone , as opposed to the carina terminating well before it approaches the ventral midline in Simopone .

8 Metabasitarsus lacks a ventral glandular groove in Vicinopone , as opposed to the universal presence of such a groove in Simopone .

9 AII (petiole) tergite in dorsal view is elongate and barrel-shaped in Vicinopone , as opposed to flattened and laterally marginate in Simopone (AIIW/AIIL 0.68–0.75 in Vicinopone, AIIW /AIIL 0.79–1.30 in Simopone ).

10 Cinctus of AIV is cross-ribbed in Vicinopone , as opposed to smooth in Simopone .