Pheidole rugosula Forel

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 : 49

Taxon classification Animalia Hymenoptera Formicidae

Pheidole rugosula Forel Figs 86, 88N

Pheidole rugosula . Pheidole variabilis var. rugosula Forel 1902a: 423 (s.w.) AUSTRALIA, Bong-Bong, N.S.W. (Froggatt). Raised to species Berry et al. 1997: 29.

Pheidole Note: The elevation to species rank proposed by Berry et al. (1997) had been heretofore overlooked by Bolton (2014).

Diagnosis among introduced Pheidole .

Yellowish brown. MajorHW 0.88, HL 0.94, SL 0.45, CI 94, SI 51 (n=1). Head subquadrate (Fig. 7); with distinct parallel rugae extending from frontal lobes posterior to apices of frontal carinae. Shorter lengths of rugae present across entire posterior region of head and extending to posterior margin in full-face view (Fig. 24). Promesonotum in profile forming a single dome (Fig. 4), lacking a distinct mound or prominence on the posterior slope. Promesonotal dorsum glossy with thin but distinct subparallel striae running oblique to the longitudinal midline (Fig. 20). Pronotal striae in dorsal view mostly oblique (Fig. 20). Postpetiole not swollen relative to petiole (Fig. 3). MinorHW 0.45, HL 0.48, SL 0.41, CI 95, SI 91 (n=1). Head with well-defined, long segments of rugae running longitudinally from below the eyes to the posterior head margin (Fig. 38). Frontal carinae distinct and reaching towards the posterior head margin, although they may occasionally be interrupted (Fig. 38). Punctate ground sculpture present on lateral surfaces of head and just mesad of the frontal carinae, but median portion of head with a large glossy section (Fig. 38). Antennal scapes reach but do not surpass posterior head margin (Fig. 41). Promesonotum in profile forming a single dome (Fig. 42), lacking a distinct mound or prominence on the posterior slope. Postpetiole not swollen relative to petiole (Fig. 3).

Identification, taxonomy and systematics.

Pheidole rugosula is a small, brownish yellow, short-limbed species with moderate head sculpturing that most likely belongs to the Australian-New Guinea clade that includes close relatives of Pheidole variabilis Mayr. The head sculpturing of both the major (Fig. 10) and the minor (Fig. 38) is distinct among all other Pheidole species treated here. These characters easily separate Pheidole rugosula from Pheidole megacephala (Fig. 24, Fig. 36). These same characters, together with a more sculptured promesonotal dorsum (Fig. 20, major) and stout propodeal spines, can be used to separate Pheidole rugosula from its two other congeners that are established in New Zealand, Pheidole proxima and Pheidole vigilans (which is also much larger, major HW> 1.20 mm). There is a bewildering diversity of native Australian (and to a lesser extent New Guinea) Pheidole that approach the morphology of Pheidole rugosula . Additional characters for identifying New Zealand Pheidole species are provided in Berry et al. (1997). A significant revision of the Pheidole variabilis group is required before Pheidole rugosula can be reliably separated from these species.

Biology.

In New Zealand, Pheidole rugosula is strongly associated with human disturbance and is the most commonly encountered of the four Pheidole species established in New Zealand ( Berry et al. 1997). It has been recorded frequently from gardens, orchards, structures and urban areas. The species was reported nesting in compost, in the soil of vegetable gardens, in the soil of lawns, and near rubbish baskets ( Berry et al. 1997; Harris et al. 2005b). It has also been recorded as scavenging dead arthropods, human food waste, nuts and seeds, and is often found associated with rotting fruit ( Berry et al. 1997; Harris et al. 2005b). Other collection records suggest Pheidole rugosula will forage arboreally. Berry et al. (1997) also mention that label data suggests the species was collected several times attacking ootheca of mantids, including those of the native mantid Orthodera novaezealandiae (Colenso).

Distribution.

Pheidole rugosula is believed to be native to the New South Wales region of Australia. The only country where the species has established is New Zealand ( Berry et al. 1997). Berry et al. (1997) published museum records of Pheidole rugosula from New Zealand. The first known occurrence of Pheidole rugosula in New Zealand is from Takapuna, where it was collected in 1958 and it had reached Auckland by 1963. Since then it has been found across the Auckland and Waikato regions.

Risk statement.

Pheidole rugosula is considered to be a nuisance pest around urban areas in New Zealand ( Harris et al. 2005b), where foragers are attracted to pet food left out and to windfall fruit. Although it occurs in native habitats in New Zealand, its impacts are unknown. Collection data indicating a Pheidole rugosula attack of native mantids suggest it could have some negative impact on native biodiversity, however.