Morphology, ecology and biogeography of Myrmecina sicula André, 1882, rediscovered after 140 years (Hymenoptera, Formicidae)

Enrico Schifani,Antonio Scupola,Antonio Alicata

doi:10.21426/b635048444

Abstract

The ant genus Myrmecina, whose diversity is mostly concentrated in SE-Asia and Oceania, counts four W-Palearctic species. The extremely euryecious and well-studied Myrmecina graminicola occurs from Iberia to the Caucasus and from the Maghreb to Scandinavia, while three little-known species (M. atlantis, M. melonii and M. sicula) coexist with M. graminicola in their narrow Maghrebian, Sardinian and Sicilian ranges, respectively. Myrmecina sicula has been described about 140 years ago from a single site and two specimens only. Their unique morphology suggested the validity of this taxon ever since, but no additional specimens were found in the following century. We present the results of decades of sampling efforts across Sicily, resulting in the collection of M. graminicola from 70 sites and M. sicula from 13 sites. We confirm M. sicula unique morphological identity and report on the marked distributional and ecological differences between the two species. Myrmecina graminicola is widespread and inhabits diverse, mainly forested habitats from lowland to high mountain sites, while M. sicula was found in a very narrow region of old carbonate platform between NW-Sicily and the Egadi Islands, mostly in sparsely vegetated sites at mid to low-altitude. Reviewing their common morphological and biogeographic traits, we propose to consider M. atlantis, M. melonii and M. sicula as a distinct M. sicula complex, whose identity and history deserves further investigation through molecular analyses.

Highlights

The genus Myrmecina Curtis, 1829 is part of the myrmicine ant tribe Crematogastrini Forel, 1893 (Ward et al 2015) and belongs to the Myrmecina genus-group, an isolated lineage that arose about 62 Mya and includes the living genera Acanthomyrmex Emery, 1893, Dilobocondyla Santschi, 1910, Perissomyrmex Smith, M.R., 1947 and Pristomyrmex Mayr, 1947 (Blaimer et al 2018), and the fossil genus Thanacomyrmex Chény, Wang & Perrichot, 2019 (Chény et al 2019)
Altitudinal ranges of the two species in Sicily are clearly different according to our sampling data and so are the habitat in which the two were more often collected (Fig. 4)
We are reasonably sure that the occurrence data we present are at least close to represent the entirety of all unpublished Myrmecina records from Sicily, and our extensive survey appears to be considerable as a good coverage of the genus distribution on the island

Summary

Introduction

The genus Myrmecina Curtis, 1829 is part of the myrmicine ant tribe Crematogastrini Forel, 1893 (Ward et al 2015) and belongs to the Myrmecina genus-group, an isolated lineage that arose about 62 Mya and includes the living genera Acanthomyrmex Emery, 1893, Dilobocondyla Santschi, 1910, Perissomyrmex Smith, M.R., 1947 and Pristomyrmex Mayr, 1947 (Blaimer et al 2018), and the fossil genus Thanacomyrmex Chény, Wang & Perrichot, 2019 (Chény et al 2019). Collected, Myrmecina ants generally form small-sized colonies, nest in the soil or in decaying wood, and forage on the leaf litter (Satria & Yamane 2019). Their biology is usually little-known, but at least some oriental species are thought to be specialized predators of oribatid mites (Masuko 1994), while some others are host of myrmecophilous mites of the same group (Aoki et al 1994; Ito & Takaku 1994; Ito & Aoki 2003). M. graminicola (Latreille, 1802) has recently attracted attention being the first ant among the very few animals known to escape from danger by actively curling itself into a ball and rolling away (Grasso et al 2020)

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