Pheidole fervens F. Smith

Sarnat, Eli M., Fischer, Georg, Guenard, Benoit & Economo, Evan P., 2015, Introduced Pheidole of the world: taxonomy, biology and distribution, ZooKeys 543, pp. 1-109 : 24-25

Taxon classification Animalia Hymenoptera Formicidae

Pheidole fervens F. Smith Figs 76, 88c

Pheidole fervens . Pheidole fervens Smith, F. 1858: 176 (s.) SINGAPORE (BMNH). Lectotype (s.) (CASENT0901520) designated: Fischer and Fisher 2013: 322.

Pheidole pungens . Solenopsis pungens Smith 1861: 48. INDONESIA, Menado, Sulawesi (A.R. Wallace). Combination in Pheidologeton : Donisthorpe 1932: 469; in Pheidole : Bolton 1995: 328. Junior synonym of Pheidole fervens ; lectotype (s.) designated: Eguchi 2004b: 198.

Pheidole javana . Pheidole javana Mayr, 1867: 66 (s.w.) INDONESIA, Batavia [Jakarta], Java. Junior synonym of Pheidole fervens : Wilson and Taylor 1967: 45. Lectotype (s.) designated: Eguchi 2004b.

Pheidole cavannae . Pheidole cavannae Emery 1887: 464 (footnote) (s.) NEW CALEDONIA. Subspecies of Pheidole oceanica : Emery 1914: 401. Junior synonym of Pheidole fervens : Wilson and Taylor 1967: 45.

Pheidole dharmsalana . Pheidole javana var. dharmsalana Forel 1902c: 184, 198 (s.) INDIA, Dharmsala (Sage). [Also described as new by Forel 1902: 546]. Subspecies of Pheidole fervens : Bolton 1995: 320. Junior synonym of Pheidole fervens ; lectotype (s.) designated: Eguchi 2004b: 198.

Pheidole amia . Pheidole amia Forel 1912: 60 (s.w.) TAIWAN, Takao [Kaohsiung]. Junior synonym of Pheidole fervens ; lectotype designated: Eguchi 2004b: 197.

Pheidole dolenda . Pheidole javana var. dolenda Forel 1912: 60 (s.w.) TAIWAN, Akau. Subspecies of Pheidole fervens : Bolton 1995: 320. Junior synonym of Pheidole fervens ; lectotype designated: Eguchi 2004b: 198.

Pheidole nigriscapa . Pheidole oceanica subsp. nigriscapa Santschi, 1928: 48 (s.w.) SAMOA, Apia, Upolu (H. Swale). Junior synonym of Pheidole fervens : Wilson and Taylor 1967: 45.

Pheidole tahitiana . Pheidole oceanica subsp. nigriscapa var. tahitiana Santschi [in Cheesman and Crawley 1928]: 516. FRENCH POLYNESIA, Tahiti. Unavailable name; material referred to Pheidole fervens by Wilson and Taylor 1967: 45.

Pheidole desucta . Pheidole javana var. desucta Wheeler, W.M. 1929: 2 (s.w.q.) CHINA, Back Liang. Subspecies of Pheidole fervens : Bolton 1995: 320. Junior synonym of Pheidole fervens : Eguchi 2001a: 53. Lectotype designated: Eguchi 2004b.

Pheidole soror . Pheidole javana var. soror Santschi 1937: 369 (s.w.) TAIWAN, Hokuto. Subspecies of Pheidole fervens : Bolton 1995: 330. Junior synonym of Pheidole fervens ; lectotype designated: Eguchi 2004b: 198.

Pheidole azumai . Pheidole nodus st. azumai Santschi 1941: 274 (s.w.) JAPAN, Tennooji, Osaka. Junior synonym of Pheidole fervens ; lectotype designated: Eguchi 2004b: 198.

Diagnosis among introduced Pheidole .

Color yellowish brown to dark brown. MajorHW 1.13-1.44, HL 1.13-1.56, SL 0.80-0.95, CI 92-100, SI 61-71 (n=15, Eguchi 2001a; 2008; Fischer and Fisher 2013). Head square to subquadrate (Fig. 7); rugoreticulate on posterolateral lobes and laterad of frontal carinae (Fig. 13a), but frons dominated by long, well-organized and parallel longitudinal rugae (Fig. 13b). Antennal scrobes indistinct to moderately impressed, but frontal carinae always forming a border capable of accepting the antennal scape (Fig. 13c). Frontal carinae relatively longer, extend 4/5 distance of head before terminating (Fig. 14). Promesonotum in profile with two convexities (Fig. 5), the large anterior dome in addition to a distinct mound or prominence on the posterior slope. Postpetiole not swollen relative to petiole (Fig. 3). MinorHW 0.52-0.63, HL 0.66-0.73, SL 0.77-0.87, CI 79-88, SI 133-154 (n=16, Eguchi 2001a; 2008; Fischer and Fisher 2013). Head predominantly glossy (Fig. 36), lacking punctation or rugulae above eye level. Posterior head margin weakly convex to flat in full-face view (Fig. 45). Antennal scapes long (e.g. Fig. 39), but not surpassing the posterior head margin by more than 2 × eye length. Promesonotum in profile with two convexities, the large anterior dome (Fig. 43a) in addition to a distinct prominence on the posterior slope (Fig. 43b). Promesonotal prominence relatively flat (Fig. 49a). Metanotal depression relatively deep (Fig. 49b). Petiole and postpetiole glossy to very weakly sculptured laterally (Fig. 48). Postpetiole not swollen relative to petiole (Fig. 3).

Identification, taxonomy and systematics.

Pheidole fervens is a medium to large sized species with long limbs. It belongs to the Pheidole fervens clade along with its Australasian congeners Pheidole cariniceps , Pheidole hospes , Pheidole impressiceps , and Pheidole oceanica ( Economo et al. 2015). The major workers have strong cephalic rugulae that become reticulated towards the posterior of the head and the minor workers have completely glossy heads with very long antennal scapes. Majors and minors of the species can be separated from those of Pheidole megacephala and Pheidole noda by the postpetiole which is not swollen compared to the petiole (Fig. 3), and the promesonotum which has the large anterior dome in addition to a distinct prominence on the posterior slope (Fig. 5, major; Fig. 43, minor). The minors of Pheidole fervens can also be separated from those of Pheidole megacephala by their larger size and longer antennal scapes (Fig. 39). The majors are easily distinguished from Pheidole megacephala by the very sculptured head (Fig. 13).

Among species treated here, Pheidole fervens is most easily confused with its close relative, Pheidole indica , and the characters used to separate these two are subtle. For both subcastes, the promesonotal prominence is flatter in Pheidole fervens (Fig. 49a, minor; Fig. 63a, major) compared to that of Pheidole indica (Fig. 50a, minor; Fig. 64a, major). The eyes of Pheidole fervens minors (Fig. 65) are relatively smaller than those of Pheidole indica minors (Fig. 66), especially in comparison to antennal segment 10. The propodeal spines of Pheidole fervens are weaker, narrower, and more downcurved in majors of Pheidole fervens (Fig. 63b) compared to those of Pheidole indica (Fig. 64b). Readers are referred to Eguchi (2004b; 2008) for characters used to separate Pheidole fervens and Pheidole indica from their Asian congeners.

In the Pacific Island region Pheidole fervens is often confused with the nearly identical Pheidole oceanica , which is native to that region. The carinae between eye and mandible are branching and reticulated in the majors of Pheidole fervens (Fig. 67), versus parallel and not reticulated in those of Pheidole oceanica (Fig. 68). This character was erroneously reversed in the key provided in Sarnat and Economo (2012). The minors are more difficult to separate, but in Pheidole fervens the length of propodeal spine is equal to or less than the diameter of propodeal spiracle (Fig. 69), whereas in Pheidole oceanica it is greater (Fig. 70).

Biology.

For such a ubiquitous species across its native and introduced range, very little is known about the biology of Pheidole fervens . It is a synanthropic species with a high tolerance for disturbance ( Eguchi 2004b; Fischer and Fisher 2013; Martínez 1996), but can also thrive under some degree of canopy cover ( Morrison 1996; Sarnat and Economo 2012). In Fiji, where it is likely a recent colonizer, it was collected most frequently in human dominated landscapes between 0-800 m, although several collections were also made from primary forest at low elevations. In Hawaii, where it is definitely an introduced species, it is more abundant locally in wet regions than Pheidole megacephala ( Gruner et al. 2003) and occurs in the hot lowlands only below 900 m ( Reimer 1994). In the Philippines, Pheidole fervens is found in irrigated lowlands (rice fields) where it is characterized as dominant species capable of displacing Solenopsis geminata in the dry season ( Way et al. 1998). In Japan it occurs in open land grading to forest edge ( Harada et al. 2009; Ogata 1981). Pheidole fervens recruits in large numbers to bait and forages both on the ground and on vegetation ( Sarnat and Economo 2012). Baiting experiments on Pacific Islands found that Pheidole fervens can act as a numerically and behaviorally dominant species capable of excluding other invasive ant species (including Anoplolepis gracilipes , Nylanderia bourbonica , and Tetramorium bicarinatum ) from baits ( Morrison 1996). Although foragers can be slow to discover food resources, once found they can recruit in large numbers and displace competing species ( Morrison 1996). Experiments in China suggest that Pheidole fervens can provide some degree of biotic resistance to the Red Imported Fire Ant ( Solenopsis invicta ) by acting in groups to dismember the limbs of individual fire ants ( Chen et al. 2011). Martínez (1996) suggested the California population of Pheidole fervens was polydomous, and Passera (1994) suggested the Hawaii population is unicolonial and polygynous, but detailed colony-level studies of the species are required to verify these claims. Wittenborn and Jeschke (2011) attributed their assertion that Pheidole fervens practices dependent colony founding to Harris et al. (2005a), but we were unable to find any reference to colony foundation in that report and cannot substantiate their evidence.

Distribution.

We consider Pheidole fervens as native to a broad expanse of the Indo-Malay region spanning from India east to the Philippines and south to the islands west of New Guinea. This is a broad and admittedly arbitrary boundary, but a more precise circumscription of the native range requires a population-level analysis outside the scope of the present study. In particular, it is difficult to ascertain the extent of its range into the Pacific Island region prior to the Anthropocene. The only known occurrence of Pheidole fervens from New Guinea was a single record from the westernmost part of the island ( Emery 1887b). East of New Guinea, however, the species is established on nearly all islands of the Pacific, including those which were uninhabited by any ant prior to human arrival. Although it is quite possible that Pheidole fervens reached some of these islands without human assistance - especially those between Taiwan and mainland Japan - we treat these as introduced populations. And although established on Mauritius, the species is rarely encountered there and is currently known from only two localities ( Fischer and Fisher 2013). The only record of introduction in North America is a California population that established nests in cracks of roads and along the sides of buildings in a two-block area of downtown Los Angeles ( Martínez 1996). Pheidole fervens has been collected from greenhouses in the Netherlands ( Boer and Vierbergen 2008), and is frequently intercepted by quarantine inspections ( Ward et al. 2006).

Risk statement.

Pheidole fervens can be a dominant species where it is locally abundant. Although few studies have measured the effect of Pheidole fervens on native ecosystems, we predict that it could negatively impact native arthropods. We were unable to find documentation on the effect of Pheidole fervens on agricultural systems, but it can be among the most abundant ant species in irrigated lowland crop systems such as rice fields. Pheidole fervens can also be an indoor nuisance species ( Wilson and Taylor 1967), but is not a risk for structural damage. According to New Zealand records, the species is among the most commonly intercepted ants in that country ( Ward et al. 2006). Sixty- nine percent of the interceptions were in freight from Fiji (> 92% from the Pacific Islands). Interceptions were mostly in fresh produce (69%) and cut flowers (8%). Pheidole fervens was also intercepted multiple times in air passengers’ luggage and shipping containers. The species could become more globally widespread in the future.