Pheidole parva Mayr

FISCHER, G. & FISHER, B. L., 2013, A revision of Pheidole Westwood (Hymenoptera: Formicidae) in the islands of the Southwest Indian Ocean and designation of a neotype for the invasive Pheidole megacephala, Zootaxa 3683 (4), pp. 301-356 : 340-343

Pheidole parva Mayr

( Figs. 23A–F )

Pheidole parva Mayr, 1865: 98 .

Lectotype (1 major worker) ( CASENT0319248 ) [designated here]: SRI LANKA ( NHMW) [examined]; paralectotype (1 minor worker) ( CASENT0319249 ) ( NHMW) [examined].

Pheidole parva var. decanica Forel, 1902: 175 .

Lectotype (major worker), designated by Eguchi et al. (2007): INDIA [not examined]. Junior synonym of Pheidole parva: Eguchi et al., 2007: 261 .

Pheidole flavens var. farquharensis Forel, 1907: 91 .

Holotype (minor worker): SEYCHELLES, Farquhar Atoll , v–xii.1905 (J.S. Gardiner) (BMNH) [examined]. Syn. n.

Pheidole sauteri Wheeler, 1909: 334 .

Syntypes (3 major workers, 19 minor workers): TAIWAN [not examined]. Junior synonym of Pheidole parva: Eguchi et al., 2007: 262 .

Pheidole rinae var. mala Forel, 1911: 205 .

Lectotype (major worker), designated by Eguchi (2001): INDONESIA [not examined]. Junior synonym of Pheidole parva: Eguchi et al., 2007: 261 .

Pheidole rinae r. tipuna Forel, 1912: 68 .

Lectotype (major worker), designated by Eguchi et al. (2007): TAIWAN [not examined]. Junior synonym of Pheidole parva: Eguchi et al., 2007: 262 .

Pheidole bugi Wheeler, 1919: 66 .

Lectotype (major worker), designated by Eguchi (2001): MALAYSIA (Sarawak, Borneo) [examined]. Junior synonym of Pheidole parva: Eguchi et al., 2007: 262 .

Pheidole tardus Donisthorpe, 1947: 285 .

Holotype (queen): MAURITIUS, Rose Hill, 07.v.1946 (R. Mamet) ( BMNH) [examined]. Syn. n.

Diagnosis: Small species (WL major 0.73–0.84 mm, WL minor 0.52–0.63 mm) with both worker castes prominently sculptured, promesonotal process absent or inconspicuous, scapes and legs of minor workers short (SI 85–93, FI 91–96), scapes and legs of major workers moderately short (SI 47–51, FI 63–68). Major head rectangular (CI 88–93) with broadly V-shaped posterior emargination, frontal carinae very short or inconspicuous, scrobe weakly developed, submedian hypostomal teeth large, median process present, promesonotum high-domed, strongly convex in profile, spines short-triangular (PSLI 12–16), metatibia with decumbent pilosity and longer erect hairs along outer edge. Minor head subrectangular, punctate, often overlain with rugoreticulate sculpture, scapes, when laid back, not reaching or barely surpassing beyond posterior head margin (SI 85–93), mesosoma fully punctate, spines short-spinose, postpetiole distinctly higher than long (DPpI 125–150).

Description of major workers: Measurements (n=8): HW 0.82–0.92 (0.87), HL 0.92–1.05 (0.97), SL 0.41– 0.43 (0.42), MDL 0.48–0.51 (0.50), EL 0.12–0.13 (0.12), WL 0.73–0.84 (0.77), PNH 0.35–0.41 (0.37), PNW 0.45–0.54 (0.48), MNH 0.53–0.58 (0.55), PDH 0.26–0.27 (0.26), PTL 0.24–0.33 (0.28), PPL 0.12–0.16 (0.14), PTH 0.18–0.21 (0.20), PPH 0.12–0.18 (0.16), PTW 0.14–0.15 (0.14), PPW 0.21–0.24 (0.22), PSL 0.11–0.14 (0.12), MFL 0.55–0.60 (0.57), MTL 0.41–0.43 (0.42), CI 88–93 (89), SI 47–51 (49), MDI 54–61 (57), EI 13–15 (14), FI 63–68 (66), PSLI 12–16 (14), LPpI 71–89 (80), DPpI 146–200 (164), PpWI 147–171 (156), PpLI 39–58 (49), PpHI 81–97 (86).

Head distinctly longer than wide (CI 88–90), in full-face view rectangular with subparallel sides, posterior emargination broadly and weakly V-shaped. Mandibles smooth and shiny, moderately long (MDI 49–59). Clypeus smooth, with median carina absent, lateral carinae weak and short. Frontal carinae relatively short or inconspicuous, antennal scrobe weakly defined, posteriorly superficially punctate. Frons longitudinally rugose, interspaces smooth to superficially punctate, sides of head weakly rugoreticulate and punctate, posterior 1/3 of head increasingly irregularly rugoreticulate, with superficially punctate interspaces. Scapes relatively short (SI 47– 51), with decumbent pilosity and few long, erect, standing hairs on outer edge. Submedian hypostomal teeth large, median process conspicuously developed. Promesonotal dome high and strongly convex in profile, promesonotal process absent, posterior declivity convex to weakly angulate, humeri in dorsal view slightly laterally produced. Surface of promesonotum and lateropronotum rugoreticulate and weakly to superficially punctate, remainder of mesosoma weakly to superficially punctate with small, smooth spots. Metanotal groove very narrow, unimpressed, and with absent to superficially developed cross-ribs. Spines relatively short-acute, subtriangular in profile (PSLI 12–16). Metatibia very short (FI 58–65), with decumbent pilosity, on outer edge with additional longer, erect hairs. Postpetiole in profile about as high as long (LPpI 71–89), with small, weakly acute ventral process, in dorsal view wider anteriorly than posteriorly, and about 1.6 times wider than petiole (PpWI 147–171). Petiole and postpetiole smooth to superficially sculptured. Gaster smooth. Several short to moderately long, stiff, standing hairs on dorsal head and body, pilosity short and decumbent. Color orange-brown, legs lighter orange to yellow, gaster darker.

Description of minor workers: Measurements (n=9): HW 0.43–0.50 (0.46), HL 0.47–0.53 (0.49), SL 0.38– 0.44 (0.40), MDL 0.27–0.33 (0.29), EL 0.09–0.11 (0.10), WL 0.52–0.63 (0.56), PNH 0.21–0.25 (0.22), PNW 0.29– 0.34 (0.31), MNH 0.35–0.43 (0.38), PDH 0.18–0.22 (0.20), PTL 0.17–0.23 (0.20), PPL 0.09–0.10 (0.09), PTH 0.12–0.14 (0.13), PPH 0.10–0.12 (0.10), PTW 0.08–0.10 (0.08), PPW 0.12–0.15 (0.13), PSL 0.07–0.10 (0.08), MFL 0.40–0.47 (0.43), MTL 0.29–0.35 (0.32), CI 91–95 (93), SI 85–93 (88), MDI 61–66 (64), EI 20–23 (21), FI 91–96 (94), PSLI 15–20 (18), LPpI 83–95 (90), DPpI 125–150 (140), PpWI 144–165 (154), PpLI 41–53 (47), PpHI 79–86 (83).

Head subrectangular, slightly longer than wide (CI 91–95), sides convex, posterior head margin weakly concave, occipital carina not visible in full-face view. Mandibles relatively short (MDI 61–66) and smooth. Clypeus smooth, median carina inconspicuous to faintly developed, lateral carinae short and irregular. Face strongly punctate, punctures sometimes aligned into weak irregular rugulae. Scapes very short (SI 85–93), not reaching to or barely surpassing posterior head margin when laid back, with decumbent pilosity and some longer erect hairs along outer edge. Promesonotal outline in lateral view anteriorly flatly convex to subangulate and posteriorly elongated, with bluntly angulate posterior declivity. Metanotal groove narrow, not or shallowly impressed, with weak to superficial cross-ribs, interspaces smooth to superficially sculptured. Pronotum, mesonotum, and propodeum strongly punctate. Propodeal spines acute, short-spinose, in profile bladelike and pointing slightly anteriorly, shorter than distance between their bases (PSLI 15–20). Metafemur short (FI 91–96), metatibia with decumbent pilosity and scattered suberect hairs. Postpetiole without ventral process, lower than petiole (PpHI 80–86), and slightly higher than long (LPpI 83–95), petiole and postpetiole dorsally smooth to superficially punctate, remainder weakly punctate. Gaster smooth and shiny. Most standing hairs suberect, short to slightly longer, and stiff, with several hairs apically split or subapically branched. Color orange, legs lighter orange to yellow, gaster darker.

Discussion: Pheidole parva is a widespread and probably invasive species in parts of the Old World and belongs to the P. rinae complex ( Eguchi et al. 2007). Most likely it is an introduced species to the Malagasy region. Indeed, live ants of this species have recently been found travelling onboard different ships (K. Eguchi, personal communication). Also its ubiquity in many different habitats and microhabitats on Mauritius and the Seychelles and its presence in ports there indicate that it is well-adapted to human environments and thus a likely candidate to invade new areas through human commerce. This tiny and relatively inconspicuous ant is very common in places and can be found in soil and leaf litter, under stones or root mats, in rotten logs, foraging on or nesting in the ground, as well as in lower vegetation and even under the bark of live trees. It was collected in a variety of different habitats, from parks and gardens, to mangrove and coastal scrub, to degraded dry forest, littoral and mixed forest, and rainforest, in elevations between 1 and 445 m. Recently it was also found on the Arabian Peninsula in Saudi Arabia and in the United Arab Emirates, on farms mostly inland from the coast at elevations of 675 and 735 m. As the nests were also found under potted plants, it is very likely that P. parva has been introduced to the Arabian Peninsula by human commerce.

On the smaller islands of the Southwest Indian Ocean, P. parva can be superficially confused with P. jonas , especially because the minors are relatively similar in their morphologies. The main characters distinguishing both worker castes of these two species are: the relative length of the postpetiole in both castes (LPpI minors 83–95, LPpI majors 71–89 in P. parva , versus LPpI minors 122–163, LPpI majors 90–126 in P. jonas ); the scapes of the workers of P. parva are distinctly shorter than those of P. jonas (SI 85–93 versus SI 102–122); and the heads of majors are distinctly longer than wide (CI 88–93) in P. parva , versus on average as long as wide (CI 95–102) in P. jonas .

Additional material examined: MAURITIUS: Brise Mt., Bambous , 20.3455 S, 57.7547 E, 200 m, rainforest, 27.v.2005 (B.L. Fisher et al.); Ilot Vacoas , 20.3833 S, 57.7667 E, 5 m, 02.iii.2005, (L. Lach); Port Louis – Port , 20.1553 S, 57.5 E, 5 m, 29.v.2005, (A.V. Suarez); Ile aux Aigrettes : 06.ii.2005, (L. Lach); 20.4197 S, 57.7342 E, 13 m, Ebony litter, 24.viii.2005, (L. Lach); 20.419 S, 57.7302 E, just north of Jetty at ocean’s edge, near aviary / on kiln, 26.v.2005 (A.V. Suarez); 20.4188 S, 57.7305 E, 1 m, coastal scrub, 28.v.2005 (B.L. Fisher et al.); Rodrigues: Anse Quitor , 19.7561 S, 63.3667 E, 21 m, 15.vi.2005, (L. Lach); Canyon Tyeul , 19.7444 S, 63.3751 E, 52 m, degraded dry forest, 14.xi.2007 (A. Meunier); Grand Montagne , 19.7057 S, 63.465 E, 358 m, 14.vii.2005, (L. Lach); Marouk , 19.731 S, 63.465 E, 122 m, 17.vii.2005, (L. Lach); SAUDI ARABIA: Dhi Ain archaeological village, Al Bahah, 19.928 S, 41.4419 E, 735 m, banana field next to dry stream, 23.ix.2011 (B.L. Fisher); Ar Riyad, 25.6088 S, 45.7583 E, 675 m, isolated date farm, 26.ix.2011 (B.L. Fisher / F.A. Esteves); SEYCHELLES: Aride Island : 4.21273 S, 55.6645 E, P. grandis forest 01.vii.2010 (R. Gaigher); 4.21096 S, 55.6624 E, 110 m, forest, 05.ii.2005 (B.L. Fisher et al.); 4.21407 S, 55.6682 E, 10 m, native forest, 05.ii.2005 (B.L. Fisher et al.); Bird Island: 01.x.2010 (J. Gerlach); Conception Island: 4.66311 S, 55.3682 E, 65 m, mixed forest, 12.ii.2010 (B.L. Fisher et al.); 4.66527 S, 55.3709 E, 20 m, mixed forest, 12.ii.2010 (B.L. Fisher et al.); Cousine Island: 4.3507 S, 55.6478 E, P. grandis forest 01.vii.2010 (R. Gaigher); 4.35009 S, 55.6468 E, 60 m, Ficus forest on rocks, 07.iii.2008 (B.L. Fisher); Curieuse Island: 4.28364 S, 55.7269 E, 5 m, coastal scrub / mangrove, 04.ii.2010 (B.L. Fisher et al.); Félicité Island: 4.31991 S, 55.8691 E, 75 m, coastal scrub, 01.ii.2010 (B.L. Fisher et al.); 4.32577 S, 55.8698 E, 120 m, forest, 01.ii.2010 (B.L. Fisher et al.); La Digue Island: 4.35613 S, 55.8433 E, 300 m, forest, 31.i.2010 (B.L. Fisher et al.); 4.34419 S, 55.8419 E, 25 m, coastal scrub, 31.i.2010 (B.L. Fisher et al.); Veuve Réserve , 4.35697 S, 55.8279 E, 15 m, littoral forest, 30.i.2010 / 02.ii.2010 (B.L. Fisher et al.); Mahé Island: Beau Vallon, 4.60928 S, 55.4325 E, 15 m, park/garden, 12.ii.2010 (B.L. Fisher et al.); Cascade, 4.67494 S, 55.4982 E, 150 m, roadside, 09.ii.2010 (B.L. Fisher et al.); Glacis la Réserve , 4.71023 S, 55.5043 E, 300 m, forest and glacis, 09.ii.2010 (B.L. Fisher et al.); Port Glaud, 4.65974 S, 55.4105 E, 10 m, park/garden, 12.ii.2010 (B.L. Fisher et al.); Port Launay, 4.65892 S, 55.4107 E, 10 m, mangrove, 11.ii.2010 (B.L. Fisher et al.); North Island: 30.vii.2000 (J. Gerlach); Praslin Island: 4.33374 S, 55.7224 E, 10 m, mangrove, 03.ii.2010 (B.L. Fisher et al.); Newcome , 4.301 S, 55.6926 E, 130 m, palm forest, 06.ii.2010 (B.L. Fisher et al.); Praslin Maxime , 4.34524 S, 55.7597 E, 40 m, park/garden, 02.ii.2010 (B.L. Fisher et al.); Praslin Tower, 4.34093 S, 55.7451 E, 370 m, mixed forest, 03.ii.2010 (B.L. Fisher et al.); Vallée de Mai , 4.33103 S, 55.7389 E, 200 m, palm forest, 02.ii.2010 (B.L. Fisher et al.); Silhouette Island: 4.49076 S, 55.2534 E, 20m, coastal scrub, 21.i.2010 (B.L. Fisher et al.); La Passe , 4.48484 S, 55.2507 E, 35 m, park/garden, 19.i.2010 / 23.i.2010 (B.L. Fisher et al.); on coastal path to Anse Mondon , 4.46951 S, 55.2416 E, 10 m, coastal scrub, 23.i.2010 (B.L. Fisher et al.); on path to Anse Mondon, 4.46893 S, 55.2294 E, 255 m, forest, 23.i.2010 (B.L. Fisher et al.); UNITED ARAB EMIRATES: Wadi Wurayah farm, 25.3833 S, 56.3167 E, 02.vi.2009 (M. Hauser et al.).

Figures

FIGURE 23 Pheidole parva Forel, full-face view (A), profile (B), and dorsal view (C) of minor worker (CASENT0160279) and full-face view (D), profile (E), and dorsal view (F) of major worker (CASENT0160280).