Syllophopsis subcoeca

Syllophopsis subcoeca was described in 1894 from St Thomas, US Virgin Islands. This remained the sole published record of S. subcoeca for more than 100 years. Wetterer & Sharaf (2021) documented a greatly expanded known geographic distribution of S. subcoeca in both the New World and the Old World. These included 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, as well as eight Old World sites, in Singapore and on two islands of the Northern Mariana Islands (Tinian and Saipan). Published records of Syllophopsis cf. subcoeca from Australia, Christmas Island and Sri Lanka are probably true S. subcoeca. It is likely that S. subcoeca was introduced to the West Indies and Florida through human commerce from Southeast Asia, its native range. Syllophopsis subcoeca 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 S. subcoeca will become widespread in Florida, although seems unlikely that 'S. subcoeca' will become a significant ecological or agricultural pest. (Wetterer & Sharaf, 2021)

Identification
Wetterer & Sharaf (2021) - Syllophopsis subcoeca has been considered to be closely related to Syllophopsis australica, originally described as Monomorium subcoecum australicum based on a worker specimen from the Blue Mountains in New South Wales, Australia. In his original description, Forel (1907) discerned several subtle characters to differentiate S. australica from the types of S. subcoeca:
 * paler yellow colour
 * slightly larger size
 * deeper metanotal groove
 * slightly higher profile of the postpetiolar node.

Ettershank (1966) raised Monomorium australicum (= S. australica) to species rank, but gave no rationale for doing so.

As part of a revision of Australian Monomorium species, Heterick (2001, p. 367) examined two syntype workers of S. subcoeca (from St Thomas, US Virgin Islands) and found that they ‘lack the domed promesonotum and deeply impressed metanotal groove’ diagnostic of S. australica. Heterick (2001) concluded that S. subcoeca and S. australica are two distinct species. Heterick (2001, p. 367) also examined a fossulatum group (= Syllophopsis) nest series from Cannonvale, Queensland, Australia, that he could not assign to S. australica, which ‘closely resembles M. subcoecum overall’. Heterick (2001, p. 367) includes the Cannonvale series in his key of workers as ‘M. cf. subcoecum Emery’, distinguished by having ‘promesonotum flattened posteriad’ (in contrast with ‘promesonotum distinctly humped’ for S. australica). Three Cannonvale Syllophopsis specimens, collected by G. Montieth on 25 April 1979, are currently listed in the Australian National Insect Collection as ‘Syllophopsis cf. subcoeca’ (ANIC:32-056864-331).

Workers of Syllophopsis subcoeca look similar to Syllophopsis vitiensis from Fiji. The two species have single-ommatidium eyes, short scapes that fail to reach the posterior margin, abundant body pilosity, an acutely impressed metanotal groove, and a uniform yellow body colour. However, S. subcoeca can be readily separated by the lack of the small dent between propodeal dorsum and declivity.

In addition to S. subcoeca, only one other Syllophopsis species is known from the New World, Syllophopsis sechellensis, found on many West Indian islands and in South Florida (Wetterer and Sharaf 2017; Wetterer 2020). Although S. sechellensis is certainly native to the Old World, the extent of its original native range is unclear (Wetterer and Sharaf 2017). One character that easily distinguishes S. sechellensis from S. subcoeca is that its entire mesopleuron is matte and reticulate-punctate, whereas in S. subcoeca (and all other described Syllophopsis species) the mesopleuron is smooth and shiny. Syllophopsis sechellensis workers are also somewhat larger and darker than those of S. subcoeca. Fernández (2007) wrote, in error, that rather than Syllophopsis sechellensis, S. subcoeca has a sculptured mesopleuron.

Distribution
Deyrup (2016, p. 423) reported S. subcoeca from Dominica, writing ‘specimens were found by digging in an open, dry, scrub area’. These specimens from Dominica (Cabrits National Park; 2 May 2006; M. Deyrup), however, were misidentified; they are actually Syllophopsis sechellensis (M. Deyrup, pers. comm.), the first record of S. sechellensis from Dominica. (Wetterer & Sharaf, 2021)

Wetterer & Sharaf (2021) - Syllophopsis subcoeca is now known in the Old World from Singapore and the Northern Mariana Islands. It is very likely that some of the other published and unpublished Syllophopsis records from the Old World are true S. subcoeca, for example the series Heterick (2001) reported from Cannonvale, Australia. In addition, Framenau and Thomas (2008) reported ‘Monomorium cf. subcoecum’ (identified by B. Heterick) from Christmas Island in the Indian Ocean. Gunawardene et al. (2008) reported both ‘Monomorium hildebrandti gp sp. nr subcoecum Emery’ and ‘Monomorium hildebrandti gp sp. cf. australicum Forel’ from Sri Lanka (identified by B. Heterick). Since all other Syllophopsis species originated in the Old World, the same is almost certainly true of S. subcoeca.

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: Christmas Island, Northern Mariana Islands, Singapore. Nearctic Region: United States. Neotropical Region: Barbados, British Virgin Islands, Dominica, Grenada, Guadeloupe, Lesser Antilles, Martinique, Puerto Rico, Saint Kitts and Nevis, Saint Lucia, Trinidad and Tobago, United States Virgin Islands. Oriental Region: Sri Lanka.

Nomenclature

 * . Monomorium subcoecum Emery, 1894c: 150 (w.q.) VIRGIN IS (St Thomas I.).
 * Type-material: syntype workers (number not stated), 1 syntype queen.
 * Type-locality: Virgin Is (“Antilles”): St Thomas I. (no collector’s name).
 * Type-depository: MSNG.
 * Combination in Syllophopsis: Ward, et al. 2015: 73.
 * Status as species: Wheeler, W.M. 1908a: 128; Emery, 1922e: 173; Kusnezov, 1949a: 425; Ettershank, 1966: 92; Kempf, 1972a: 144; Bolton, 1995b: 267; Fernández, 2007b: 138; Wetterer, et al. 2016: 20; Deyrup, 2017: 76.
 * Distribution: Barbados, Dominica, Puerto Rico, U.S.A. (Florida), Virgin Is.

References based on Global Ant Biodiversity Informatics

 * Wetterer J. K., and M. R. Sharaf. 2017. Worldwide Distribution of Syllophopsis sechellensis (Hymenoptera: Formicidae). Florida Entomologist 100(2): 281-285.