Worldwide distribution of <i>Syllophopsis subcoeca</i> (Hymenoptera: Formicidae), an Old-World species long known only from the West Indies

<i>Syllophopsis</i> (Hymenoptera: Formicidae) is a taxonomically difficult and possibly polyphyletic genus of tiny, inconspicuous ants. <i>Syllophopsis subcoeca</i> (Emery) was described in 1894 from St Thomas, US Virgin Islands. This remained the sole published record of <i>S. subcoeca</i> for more than 100 years. Here, we present new descriptions of the worker and queen castes, and document a greatly expanded known geographic distribution of <i>S. subcoeca</i> in both the New World and the Old World. We compiled published and unpublished <i>S. subcoeca</i> specimen records from 67 sites. These include 59 New World sites on 12 West Indian islands (Barbados, Dominica, Grenada, Guadeloupe, Martinique, Nevis, St Croix, St John, St. Kitts, St Lucia, Tortola and Trinidad) and in southern Florida. In addition, we report records of <i>S. subcoeca</i> from eight Old World sites, in Singapore and on two islands of the Northern Mariana Islands (Tinian and Saipan). Published records of <i>Syllophopsis</i> cf. <i>subcoeca</i> from Australia, Christmas Island and Sri Lanka are probably true <i>S. subcoeca</i>. All other <i>Syllophopsis</i> species appear to have originated in the Old World; therefore, the same is almost certainly true of <i>S. subcoeca</i>. It is likely that <i>S. subcoeca</i> was introduced to the West Indies and Florida through human commerce. <i>Syllophopsis subcoeca</i> appears to be a very recent arrival to Florida, where it is now known from nine sites in Miami-Dade and Broward counties. It remains to be seen whether <i>S. subcoeca</i> will become widespread in Florida. It seems unlikely that this <i>S. subcoeca</i> will become a significant ecological or agricultural pest.