Pheidole parva

Fischer and Fisher (2013) - 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. Eguchi (2008) - This species prefers open lands, tillage and gardens to woody habitats, and nests under the ground. In rural areas of N. Vietnamese this species and Pheidole yeensis are the most dominant Pheidole species.

Identification
Fischer and Fisher (2013) - 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).

Southwest Indian Ocean
Fischer and Fisher (2013) - On the smaller islands of the Southwest Indian Ocean, P. parva can be superficially confused with Pheidole 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.

Key to Pheidole of the islands of the Southwest Indian Ocean

Indo-China
Eguchi (2008) - This species is characterized among Indo-Chinese species by the combination of the following features: in the major frontal carina almost absent; in the major hypostoma in the middle with 3 processes (median process is often low, rarely much reduced); in the minor scape exceeding posterior margin of head by less than half length of antennal segment II, or not reaching the posterior margin; in the minor maximal diameter of eye longer than antennal segment X; in the minor dorsal and lateral faces of head and mesosoma punctured; in the major and minor posterior slope of promesonotal dome lacking a conspicuous prominence/mound.

P. parva is most similar to Pheidole rabo Forel. In the minor of the latter, however, scape usually exceeds posterior margin of head by almost the length of antennal segment II, and maximal diameter of eye is almost as long as or a little shorter than antennal segment X.

Key to Pheidole of North Vietnam

Distribution
Widely distributed in the Oriental region, Austro-Malayan subregion and W. Pacific.

Distribution based on Regional Taxon Lists
Afrotropical Region: Saudi Arabia, United Arab Emirates. Indo-Australian Region: Borneo, Indonesia, Malaysia, Philippines. Malagasy Region: Mauritius, Seychelles. Oriental Region: India, Myanmar, Sri Lanka, Taiwan, Thailand, Vietnam. Palaearctic Region: China, Japan.

Nomenclature

 *  parva. Pheidole parva Mayr, 1865: 98, pl. 4, fig. 28 (s.w.) SRI LANKA. Bingham, 1903: 245 (q.). Senior synonym of bugi, decanica, mala, sauteri, tipuna: Eguchi, Yamane & Zhou, 2007: 262; of farquharensis, tarda: Fischer & Fisher, 2013: 340.
 * decanica. Pheidole parva var. decanica Forel, 1902c: 175 (s.), 192 (w.q.m.) INDIA. [Also described as new by Forel, 1902f: 542.] Junior synonym of parva: Eguchi, Yamane & Zhou, 2007: 261.
 * sauteri. Pheidole sauteri Wheeler, W.M. 1909d: 334 (s.w.) TAIWAN. Junior synonym of parva: Eguchi, Yamane & Zhou, 2007: 262.
 * mala. Pheidole rinae var. mala Forel, 1911b: 205 (s.w.) INDONESIA (Java). Junior synonym of parva: Eguchi, Yamane & Zhou, 2007: 262.
 * tipuna. Pheidole rinae r. tipuna Forel, 1912a: 68 (s.w.) TAIWAN. Junior synonym of parva: Eguchi, Yamane & Zhou, 2007: 262.
 * bugi. Pheidole bugi Wheeler, W.M. 1919e: 66 (s.w.) BORNEO. Junior synonym of parva: Eguchi, Yamane & Zhou, 2007: 262. See also: Eguchi, 2001b: 37.
 * farquharensis. Pheidole flavens var. farquharensis Forel, 1907d: 91 (w.) MADAGASCAR. Junior synonym of parva: Fischer & Fisher, 2013: 340. See also: Wilson, 2003: 419.
 * tarda. Pheidole (Pheidole) tardus Donisthorpe, 1947a: 285 (q.) MAURITIUS. Junior synonym of parva: Fischer & Fisher, 2013: 341.

Worker
Eguchi (2008) - data from Eguchi, Yamane & Zhou 2007: Major - HL 0.96–1.07 mm; HW 0.85–0.92 mm; CI 85–92; SL 0.41–0.45 mm; SI 45–51; FL 0.57–0.62 mm; FI 64–68. Minor - HL 0.43–0.54 mm; HW 0.39–0.50 mm; CI 88–94; SL 0.38–0.46 mm; SI 84–102; FL 0.39–0.48 mm; FI 93–109.

Major - Head in lateral view not or very weakly impressed on vertex; frons to anterior part of vertex longitudinally rugose; posterior part of vertex rusogo-reticulate; dorsal and dorsolateral faces of vertexal lobe reticulate or rusogo-reticulate; frontal carina absent or inconspicuous (present just as weak rugulae); antennal scrobe absent; median longitudinal carina on clypeus absent, or rarely present but weak; hypostoma with median and submedian processes in addition to conspicuous lateral processes; median process often lower than submedian process, or sometimes almost disappearing; submedian processes usually conspicuous; outer surface of mandible (excluding area around the base) smooth or dimly rugose partly, sparsely with (very) short appressed hairs; antenna with a 3-segmented club; maximal diameter of eye longer than antennal segment X. Promesonotal dome in dorsal view rugoso-reticulate or irregularly rugose with interspaces smooth or dimly to distinctly punctured, or punctured weakly; the dome in lateral view at most with an inconspicuous mound on its posterior slope; humerus weakly produced laterad; the dome at the humeri almost as broad as or broader than at the bottom. Petiole much longer than postpetiole (excluding helcium); petiolar node in lateral view relatively high; postpetiole not massive; first gastral tergite weakly rugoso-punctate in its anterior 1/3 or at least around its articulation with postpetiole.

Minor - Dorsum of head punctured and often overlain by weak rugoso-reticulation; preoccipital carina absent or inconspicuous dorsally; median part of clypeus smooth or weakly punctured; median longitudinal carina absent, or present but weak; antenna with a 3-segmented club; scape exceeding posterior margin of head by less than half length of antennal segment II, or not reaching the posterior margin; maximal diameter of eye longer than antennal segment X. Mesosoma punctured; punctuation on dorsum of promesonotal dome often overlain sparsely by weak rugulae; promesonotal dome in lateral view relatively weakly convex, at most with an inconspicuous mound on its posterior slope; humerus in dorso-oblique view very weakly produced; propodeal spine elongate-triangular. Petiole much longer than postpetiole (excluding helcium); postpetiole not massive.

Fischer and Fisher (2013) - Major 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.

Minor 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.

Type Material
Eguchi (2008):

Syntypes: 1 major & 2 minors, “Ceylon” [= Sri Lanka],, examined.

Pheidole parva var. decanica. Lectotype: major, “Cochin (Inde) (Rothney)” [India], MHNG, examined; paralectotypes: 2 majors, “Cochin (Inde) (Rothney)” [India],, examined; 3 minors, “Kanara XXXI 8 (Aitken)” [India], MHNG, examined; 3 queens, “Belgaum. (Wroughton) XXXII 1c” [India], MHNG, exam- ined; 3 males, “Belgaum (Wroughton) XXXII 1b”, MHNG, examined; specimens from Poona [India] and Ceylon [Sri Lanka] (according to the original description), not examined.

Pheidole bugi. Lectotype: major, “Sarawak, Borneo, R. Thaxter”, cotype-8947, examined.

Pheidole rinae var. mala. Lectotype: major, “Semarang Java (Jacobson)”, MHNG, examined; paralectotypes: 2 majors & 3 minors, “Semarang Java (Jacobson)”, MHNG, examined.

Pheidole rinae r. tipuna. Lectotype: major, “Takao Formose (Sauter) 25” [= Kaoshung, Taiwan], MHNG, examined; paralectotypes: 3 minors, “Takao 25 Formose (Sauter)”, MHNG, examined.

Pheidole sauteri. Syntypes: 3 majors & 19 minors, “Takao, Formosa, H. Sauter” [= Kaoshung, Taiwan], MCZC cotype 20671, examined.