Proceratium californicum

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Proceratium californicum
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. californicum
Binomial name
Proceratium californicum
Cook, 1953

Proceratium californicum casent0005439 profile 1.jpg

Proceratium californicum casent0005439 dorsal 1.jpg

Specimen labels

Winkler samples yielded two workers and three dealate queens from a small patch of remnant valley oak (Quercus lobata) woodland and one worker from a roadside border of oak trees, adjacent to a golf course. Collection dates for the alates range from April 19 to May 27 (Ward 1988). Nothing else is known about the biology of Proceratium californicum.


A member of the pergandei clade. Proceratium californicum is very distinct from all the other species of the pergandei clade for its body pilosity consisting mainly of dense, short, appressed hairs and also sparse, slightly longer hairs which are subdecumbent and decumbent but rare on the antennae and lacking on the legs. Differing from its ingroup species, Proceratium melitense, in the worker by the presence of a marked propodeal suture (no visible suture in melitense) and by the antennae and legs without erect-suberect hairs, and from its outgroup species Proceratium confinium, in the worker, by the antennal socket behind the anterolateral clypeal border (strongly surpassing the anterolateral clypeal border in confinium) and by the sculpture on the head, mesosoma and petiole more superficial. (Baroni Urbani and de Andrade 2003)

Keys including this Species


United States: California.

Latitudinal Distribution Pattern

Latitudinal Range: 39.21638° to 37.01667°.

Tropical South

Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.


This species is known from only a handful of collections from California. Two of the collecting sites were oak woodlands (Ward 1988).



The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • californicum. Proceratium californicum Cook, 1953: 45, fig. (m.) U.S.A. (California).
    • Type-material: holotype male.
    • Type-locality: U.S.A: California, Santa Cruz Mts, Glenwood, 27.v.1908.
    • Type-depository: LACM.
    • [Note: Snelling, R.R. 1967: 2, stated that the holotype is “the property of the Snow Museum, Oakland, California” (now the Oakland Museum of California); but Ward, 1988: 112, records its presence in LACM.]
    • Snelling, R.R. 1967: 4 (q.); Ward, 1988: 109 (w.).
    • Status as species: Brown, 1958g: 247, 332; Smith, M.R. 1958c: 111; Snelling, R.R. 1967: 2 (redescription); Smith, D.R. 1979: 1338; Brown, 1980b: 343 (in key); Ward, 1988: 109; Bolton, 1995b: 366; Baroni Urbani & De Andrade, 2003b: 243 (redescription); Ward, 2005: 38.
    • Distribution: U.S.A.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Taxonomic Notes

This species was described from a male that was not associated with any workers; it is believed to be the same species as subsequently discovered queens (Snelling 1967) and workers (Ward 1988). Both these authors state that the species is most similar to Old World temperate species such as Proceratium melinum.



Baroni Urbani and de Andrade (2003) - Head longer than broad, its sides weakly convex in the middle, gently converging posteriorly. Vertexal margin nearly flat medially. Anteromedian part of the clypeus triangular and protruding anteriorly, dorsally with a superficially marked, bifurcated carina. Frontal carinae gently diverging posteriorly. Lateral expansions of the frontal carinae not very far from each other, higher and broader posteriorly. Head anterolaterally with a short, superficially marked longitudinal carina. Genal carina absent. Gular area not impressed. Eyes absent, represented by a few minute dots at the mid line of the head sides. First funicular joint 1/3 longer than broad. Funicular joints 2-10 about as broad as long. Last funicular joint as long as the sum of the joints 8-10. Scapes slightly short of the vertexal margin and gently thickening apically. Antennal torulus behind the lateral border of the clypeus. Masticatory margin of the mandibles with 4-5 denticles before the pointed apical tooth. Palp formula 4,3.

Mesosoma about as long as the head (mandibles included). Pronotum and mesonotum convex in profile. Propodeal suture impressed. Basal face of the propodeum slightly declivous posteriorly. Area between basal and declivous faces of the propodeum concave. Propodeal concavity dorsally carinate and laterally denticulate. Sometimes the propodeal carina incomplete medially and a small peak may be present. Declivous face of the propodeum marginate. Propodeal lobes subround and marginate only. Propodeal spiracle round and above mid height in lateral view.

Petiole in side view convex. Petiole in dorsal view with the sides anteriorly shortly diverging and strongly convex posteriorly. Anterior border of the petiole gently concave and carinate, the carina denticulate on each side. Posterior half of the petiolar dorsum with a median, longitudinal carina. Ventral process of the petiole lamelliform and short. Postpetiole robust; its anterior face high and broader than the petiole; its sides gently convex. Postpetiolar sternite, anteromedially, with a marked subtriangular projection. Posterior half of the postpetiolar sternite convex. Constriction between postpetiole and first gastral segment impressed. Gastral tergite I strongly convex on the curvature. Remaining gastral tergites and sternites originating just after the curvature.

Legs slender. All tibiae with a pectinate spur. Spurs of fore legs with basal spine. Fore basitarsi as long as the mid ones. Hind basitarsi about 1/5 shorter than hind tibiae. Second tarsomere of hind leg longer than the pretarsus. Pretarsal claws simple. Arolia present.

Sculpture. Head, mesosoma, petiole and legs finely reticulate-punctate, this sculpture more superficial on the legs. Postpetiole and gaster superficially shining and covered by minute piligerous impressions.

Body covered by hairs of three main types: (1) short, dense, appressed on the whole body; (2) slightly longer than hair type (1), subdecumbent and decumbent on the whole body, sparser on the mesosoma, rare on the antennae and absent from the legs; (3) shorter than hair type (1), dense and appressed on the funicular joints only. In addition the funicular joints bear whitish, thick, appressed, short, sparse hairs.

Colour light brown.

Measurements in mm and Indices: TL 3.82-3.96; HL 0.90-0.94; HW 0.80-0.84; EL 0.04-0.05; SL 0.68-0.70; WL 1.08-1.10; PeL 0.33; PeW 0.33-0.34; HFeL 0.76-0.80; HTiL 0.68-0.70; HBaL 0.54-0.56; LS4 0.34-0.36; LT4 0.90-0.93; CI 89.0-89.4; S174.5-75.6; IGR 0.38-0.39.


Baroni Urbani and de Andrade (2003) - Differing from the worker in the following details: eyes about 1/5 of the head length and with well defined ommatidia. Ocular pilosity present. Ocelli present. Mandibles with 6-7 denticles before the apical tooth.

Mesosoma robust. Scutellum as long as the length of the sides of the basal face of the propodeum; its sides gently converging into a convex posterior border. Metanotum with a denticle. Declivous face of the propodeum without a peak on the center of the concavity. Each side of the propodeal concavity with a subround tooth of variable size.

Petiolar node in side view narrower and higher. Ventral process of the petiole slightly more developed and subtriangular.

Fore wings of our type 2, hind wings of our type 2 as defined in the description of the genus.

Pilosity and colour as in the worker.

Measurements in mm and Indices: TL 4.88-5.18; HL 0.96-1.04; HW 0.90-0.96; EL 0.19-0.20; SL 0.72-0.82; WL 1.36-1.44; PeL 0.39; PeW 0.40-0.44; HFeL 0.92-0.98; HTiL 0.81-0.84; HBaL 0.67-0.72; LS4 0.52; LT4 1.30-1.40; CI 92.3-94.0; ST 75.0-79.0; IGR 0.37-0.40.


Baroni Urbani and de Andrade (2003) - Not available for the present study. The redescription of the Holotype and the drawings by Snelling (1967) should be largely sufficient to differentiate it from closely related species.

Type Material

Baroni Urbani and de Andrade (2003) - Male. Type locality: Glenwood, California, USA. A male in Los Angeles County Museum of Natural History (Snelling, 1969) not available for the present study.


  • Baroni Urbani, C., de Andrade, M.L. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie, 36, 1–492. (page 243, figs. 101, 102 worker, queen described)
  • Brown, W. L., Jr. 1958g. Contributions toward a reclassification of the Formicidae. II. Tribe Ectatommini (Hymenoptera). Bulletin of the Museum of Comparative Zoology 118: 173-362 (page 332, see also)
  • Cook, T. W. 1953. The ants of California. Palo Alto, California: Pacific Books: 462 pp. (page 45, fig. male described)
  • Snelling, R. R. 1967. Studies on California ants. 3. The taxonomic status of Proceratium californicum Cook (Hymenoptera: Formicidae). Contr. Sci. (Los Angel.) 124: 1-10 (page 1, queen described)
  • Ward, P. S. 1988. Mesic elements in the western Nearctic ant fauna: taxonomic and biological notes on Amblyopone, Proceratium, and Smithistruma (Hymenoptera: Formicidae). J. Kans. Entomol. Soc. 61: 102-124 (page 109, worker described)

References based on Global Ant Biodiversity Informatics

  • Baroni Urbani C., and M.L de Andrade. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie 36: 1-480.
  • Snelling R. R. 1967. Studies on California ants. 3. The taxonomic status of Proceratium californicum Cook (Hymenoptera: Formicidae). Contributions in Science (Los Angeles) 124: 1-10.
  • Ward P. S. 1987. Distribution of the introduced Argentine ant (Iridomyrmex humilis) in natural habitats of the lower Sacramento Valley and its effects on the indigenous ant fauna. Hilgardia 55: 1-16
  • Ward, P. S. 1988. Mesic Elemets in the Western Nearctic Ant Fauna: Taxonomic and Bilogical Notes on Amblyopone, Proceratium, and Smithistruma (Hymenoptera: Formicidae) Journal of the Kansas Entomological Society. 61:102-124