Pheidole nodus

This species occurs from open lands to relatively developed forests, and nests in the soil, under shelters on the ground, and in rotting logs. According to Eguchi (2004b) workers gather seeds of sesame and amaranthus put on the ground in S. Japan. Majors serve as repletes. In N. Vietnam this species is one of the prey of Aenictus dentatus. (Eguchi 2008)

Identification
Pheidole noda is distinguished among Indo-Chinese species by the combination of the following characteristics: in the major head in full-face view relatively broadly and deeply concave posteriorly; in the major dorsum of head sparsely bearing standing hairs which are much longer and distinctly thicker than background hairs; in the major posterior part of vertex and dorsal and lateral faces of vertexal lobe rugoso-reticulate; in the major subpetiolar process absent or at most present as a low carina; in the major and minor postpetiole massive. Pheidole tumida is similar to P. noda. At present it is impossible to separate the two by minor’s morphology. However, the major of P. tumida has a very large lobate subpetiolar process. (Eguchi 2008)

Distribution
Widely distributed in the Manchurian subregion and Oriental region.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia. Oriental Region: Bangladesh, India, Sri Lanka, Taiwan, Thailand, Vietnam. Palaearctic Region: Japan, Republic of Korea.

Biology
Hosoishi et al. (2019) examined winter foraging activity in western Japan. They found foraging activity was generally low, except during relatively warm periods when the surface ground temperature was above 6–7°C or soil temperature was above 4–5°C. Tetramorium tsushimae, Messor aciculatus and Pheidole nodus were the most abundant in the open land type, whereas Nylanderia flavipes, Pheidole nodus and Crematogaster osakensis were the most abundant in the forest type. Bait preference varied among the different species, e.g., Pheidole nodus preferred tuna over honey, whereas Nylanderia flavipes similarly responded to tuna and honey.

Nomenclature

 *  nodus. Pheidole nodus Smith, F. 1874: 407 (s.) JAPAN. Forel, 1900e: 268 (w.); Wheeler, W.M. 1906c: 309 (q.); Ogata, 1982: 196 (m.); Wheeler, G.C. & Wheeler, J. 1953b: 75 (l.); Imai & Kubota, 1972: 197 (k.); Imai & Kubota, 1975: 391 (k.). Senior synonym of micantiventris, praevexata, rhombinoda: Yasumatsu, 1962: 96; of treubi: Eguchi, 2001a: 18; of flebilis, formosensis, stella, taprobanae (unresolved junior homonym) and material of the unavailable name gratiosa referred here: Eguchi, 2008: 59.
 * rhombinoda. Pheidole rhombinoda Mayr, 1879: 678 (s.) INDIA. Bingham, 1903: 251 (q.). Subspecies of noda: Wheeler, W.M. 1929f: 3; Santschi, 1937h: 371. Junior synonym of noda: Yasumatsu, 1962: 96. [Misspelled as rhomboida by Santschi, 1925f: 83.]
 * micantiventris. Pheidole rhombinoda var. micantiventris Mayr, 1897: 427 (s.) SRI LANKA. Junior synonym of noda: Yasumatsu, 1962: 96.
 * taprobanae. Pheidole rhombinoda var. taprobanae Forel, 1902c: 178 (s.), 195 (w.) SRI LANKA. [Unresolved junior primary homonym of taprobanae Smith, F. 1858b: 175, above.] [Also described as new by Forel, 1902f: 544.] Subspecies of rhombinoda: Forel, 1913e: 662; of noda: Santschi, 1937h: 371. Junior synonym of noda: Eguchi, 2008: 59.
 * treubi. Pheidole treubi Forel, 1905c: 19 (s.q.) INDONESIA (Java). Junior synonym of noda: Eguchi, 2001a: 18.
 * stella. Pheidole rhombinoda subsp. stella Forel, 1911d: 380 (s.) INDIA. Subspecies of noda: Wheeler, W.M. 1929f: 3. Junior synonym of noda: Eguchi, 2008: 59.
 * formosensis. Pheidole rhombinoda var. formosensis Forel, 1913f: 193 (s.w.q.m.) TAIWAN. Subspecies of noda: Santschi, 1937h: 370. Junior synonym of noda: Eguchi, 2008: 59.
 * praevexata. Pheidole nodus var. praevexata Wheeler, W.M. 1929f: 3 (s.w.q.) JAPAN. Junior synonym of noda: Yasumatsu, 1962: 96.
 * flebilis. Pheidole nodus var. flebilis Santschi, 1937h: 370 (s.w.) TAIWAN. Junior synonym of noda: Eguchi, 2008: 59.

Type Material
Eguchi (2008):

Pheidole nodus. Syntype(s): major, Hyogo, Japan, not examined.

Pheidole rhombinoda. Syntype: 1 major, “Calcutta Sm. 73” [India], NHMW, examined.

Pheidole rhombinoda var. stella. Syntypes: 2 majors, “Sikkim 4000 ft (Bingham)” [Sikkim, Himalaya, 1200 m alt., India], MHNG, examined, 1 (intact major) of the two syntype majors designated here as the lectotype.

Pheidole rhombinoda var. formosensis. Syntypes: 3 majors, “Kankau Erde V.12 No 721” [Kankau, Taiwan], MHNG, examined; 3 minors, “Kankau No 83”, MHNG, examined; 2 queens, “Taihorin No. 41” [Taihorin, Taiwan], MHNG, examined; 3 males, “Taihorin No 28”, MHNG, examined.

Pheidole rhombinoda var. taprobanae. Syntypes: 2 majors & 3 minors, “Ceylon (Yerbury) 10”, MNHG, examined.

Pheidole nodus var. flebilis. Syntypes: 1 major & 3 minors, “Hori Form K Sato” [Hori, Taiwan], NHMB, examined.

Pheidole nodus st. rhombinoda var. gratiosa. Material referable to this form: 1 major & 1 minor, “Indes Kanara Ritken.” [Kanara, India], NHMB, examined.

Pheidole treubi. Lectotype: major, Buitenzorg [Bogor, Java], MHNG, examined; paralectotype(s): queen(s) from the same locality (according to the original description), not examined.

Worker
Eguchi (2008) - Major (n=5). — HL 1.69–1.91 mm; HW 1.58–1.82 mm; CI 93–98; SL 1.00–1.12 mm; SI 56–65; FL 1.46–1.62 mm; FI 84–94. Minor (n=5). — HL 0.71–0.82 mm; HW 0.57–0.66 mm; CI 80–82; SL 0.91–1.07 mm; SI 157–162; FL 1.03–1.22 mm; FI 177–185.

Major — Head in lateral view not or hardly impressed on vertex, in full-face view relatively broadly concave posteriorly; dorsum of head sparsely bearing standing hairs which are much longer and distinctly thicker than many short decumbent-subdecumbent background hairs; frons and anterior part of vertex rugose longitudinally; posterior part of vertex and dorsal and lateral faces of vertexal lobe reticulate or rugoso-reticulate; frontal carina conspicuous; antennal scrobe inconspicuous; clypeus with a conspicuous median longitudinal carina; hypostoma without median and submedian processes, but with a pair of conspicuous lateral processes; antenna with a 3-segmented club; maximal diameter of eye as long as or longer than antennal segment X. Promesonotal dome sparsely with long and thick standing hairs, in dorsal view rugose or rugoso-reticulate transversely, in lateral view with a conspicuous prominence on its posterior slope; humerus not or hardly produced laterad; the dome at the humeri narrower than at the bottom. Petiole shorter than postpetiole (excluding helcium); anterolateral part of petioler peduncle in dorsal view somewhat produced laterad; subpetiolar process absent, or at most present as a longitudinal carina; postpetiole massive. First gastral tergite weakly rugoso-punctured in its anterior 1/3 to 1/2, and shagreened to smooth in the remainder part.

Minor — Frons and vertex smooth, or rarely shagreened; area between antennal insertion and eye often rugose sparsely and weakly, or rugoso-punctate weakly; preoccipital carina conspicuous dorsally and laterally; median part of clypeus smooth, usually (but not always) with a weak median longitudinal carina; antenna with a 3-segmented club; scape extending far beyond posterolateral margin of head; maximal diameter of eye shorter than antennal segment X. Promesonotal dome largely smooth, in lateral view with a conspicuous mound on its posterior slope; humerus of the dome in dorso-oblique view not produced/raised; mesopleuron, metapleuron and lateral face of propodeum weakly or dimly punctured at least partly; propodeal spine small, or sometimes reduced to a tiny dent. Petiole shorter than postpetiole (excluding helcium); postpetiole massive.