Crematogaster difformis

Crematogaster difformis nests in the hollow rhizomes of the epiphytic fern Lecanopteris sp. and in the enclosed layers of old leaves of another epiphyte fern, Platycerium sp. Both epiphytic ferns establish themselves in the crown of emergent trees in Bornean lowland forests. All mature plants of the two fern species harbour C. difformis, and it always nests within the fern. The ants tend to establish territories encompassing most of the surface areas of the tree crowns where they live, defending not only their host ferns, but also host emergent trees from herbivores inside the territories. Workers of C. difformis prune lianas climbing the emergent trees on which their partner myrmecophytic ferns grow, and the distribution of the lianas is reduced by the presence of C. difformis nests inside the ferns. (Tanaka & Itioka 2011).

Identification
Hosoishi and Ogata (2009) - This species is similar to Crematogaster ampullaris and Crematogaster sewardi, but can be distinguished by the medially directed setae on the posterior portion of the fourth abdominal tergite.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Philippines, Singapore. Oriental Region: Thailand.

Nomenclature

 * . Crematogaster difformis Smith, F. 1857a: 76 (w.) BORNEO (East Malaysia: Sarawak), SINGAPORE.
 * Type-material: lectotype worker (by designation of Hosoishi & Ogata, 2009b: 22), 5 paralectotype workers.
 * Type-locality: lectotype Singapore: “Sing. 25” (A.R. Wallace); paralectotypes: 1 with same data, 4 Malaysia: Sarawak, “Sar. 33” (A.R. Wallace).
 * Type-depository: OXUM.
 * [Misspelled as deformis by Roger, 1863b: 37, and many others; misspelled as diformis by Wheeler, W.M. 1919e: 74.]
 * Emery, 1901g: 574 (q.); Forel, 1909d: 225 (m.); Wheeler, G.C. & Wheeler, J. 1952b: 261 (l.).
 * Combination in C. (Physocrema): Forel, 1912f: 220.
 * Status as species: Smith, F. 1858b: 137; Mayr, 1862: 767; Mayr, 1863: 404; Roger, 1863b: 37; Mayr, 1867a: 105 (redescription); Smith, F. 1871a: 329; Mayr, 1872: 153; Mayr, 1879: 680 (in key); Emery, 1887b: 467; Emery, 1889b: 506; André, 1892b: 53; Dalla Torre, 1893: 81; Emery, 1893e: 193; Emery, 1897d: 567; Emery, 1900d: 690; Emery, 1901g: 574; Forel, 1903a: 682; Bingham, 1903: 145; Wheeler, W.M. 1908d: 390; Forel, 1909d: 225; Forel, 1910d: 124; Forel, 1911b: 201; Forel, 1912n: 57; Forel, 1913k: 78; Forel, 1915a: 28; Viehmeyer, 1916a: 126; Wheeler, W.M. 1919e: 74; Emery, 1922e: 139; Wheeler, W.M. 1924b: 246; Donisthorpe, 1932c: 450; Menozzi, 1935a: 114; Wheeler, W.M. 1937a: 23; Donisthorpe, 1941l: 226 (in key); Chapman & Capco, 1951: 102; Baltazar, 1966: 251; Bolton, 1995b: 152; Jaitrong & Nabhitabhata, 2005: 18; Hosoishi & Ogata, 2009b: 22 (redescription); Pfeiffer, et al. 2011: 45; Khachonpisitsak, et al. 2020: 87.
 * Senior synonym of edentata: Emery, 1901g: 574; Wheeler, W.M. 1919e: 74; Emery, 1922e: 140; Bolton, 1995b: 152; Hosoishi & Ogata, 2009b: 22.
 * Distribution: Brunei, Indonesia (Java), Malaysia (Peninsula, Sabah, Sarawak), Singapore, Thailand.
 * edentata. Crematogaster edentata Mayr, 1867a: 104, pl. 2, fig. 10 (q.) INDONESIA (Java).
 * Type-material: holotype queen.
 * Type-locality: Indonesia: Java (no collector’s name).
 * Type-depository: uncertain.
 * [Note: may be in NHMW, but text says “Mus. Halle” (= Stadtmuseum Halle ?).]
 * Status as species: Dalla Torre, 1893: 81.
 * Junior synonym of difformis: Emery, 1901g: 574; Wheeler, W.M. 1919e: 74; Emery, 1922e: 140; Bolton, 1995b: 152; Hosoishi & Ogata, 2009b: 22.

Worker
Hosoishi and Ogata (2009) - HW 0.88–1.5; HL 0.84–1.34; CI 105–112; SL 0.74–1.06; SI 71–85; EL 0.15–0.28; PW 0.46–0.82; WL 1.01–1.74; PSL 0; PtL 0.26–0.48; PtW 0.19–0.4; PtH 0.15–0.26; PpL 0.16–0.28; PpW 0.2–0.4; PtHI 54–65; PtWI 74–95; PpWI 121–143; WI 90–107 (Three workers measured).

Workers with pronounced size polymorphism.

Scape just or not reaching posterior corner of head in large workers. Anterior-most portions of clypeus distinctly protruded anteriorly in large workers.

In lateral view, pronotum and mesonotum forming a single convexity; propodeum slightly raised relative to promesonotum. Anterior margin of pronotal collar slightly concave in dorsal view. Promesonotal suture sometimes visible in large workers. Metanotal groove convex posteriorly in dorsal view, deep and situated posteriorly to the posterior ridge of pronotum in lateral view; thorax strongly constricted in middle in dorsal view. In dorsal view, some longitudinal rugulae connecting between mesonotum and propodeum; the boundary distinct. Propodeal spiracle situated away from the metapleural gland orifice, the distance between them much greater than the propodeal spiracle diameter. Propodeal spines absent.

Clypeus sculptured with longitudinal rugulae.

Standing pilosity sparse on dorsal face of head, abundant on promesonotum. Dorsal face of head with decumbent setae. Clypeus with short setae. Fourth abdominal tergite with appressed setae. Dorsal setae on fourth abdominal tergite appressed and directed medially in the posterior portion.

Body color black.

Type Material
Hosoishi and Ogata (2009) - LECTOTYPE worker (large worker from SINGAPORE, TYPE HYM: 1017 1-2 / 6) (by present designation) and five paralectotype workers: one paralectotype worker from SINGAPORE; four paralectotype workers from MALAYSIA: Sarawak, Borneo [examined]. We have not been able to examine type-material of C. edentata Mayr. Although Emery synomymised it with C. (P.) difformis, it is impossible to clarify the synonymy from the original description and figure.

Crematogaster difformis

Six worker syntypes in. Labelled “Sing. 25” and “Sar. 33.” Both localities are recorded by Smith.

References based on Global Ant Biodiversity Informatics

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