Proceratium watasei

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Proceratium watasei
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. watasei
Binomial name
Proceratium watasei
(Wheeler, W.M., 1906)

Proceratium watasei casent0916701 p 1 high.jpg

Proceratium watasei casent0916701 d 1 high.jpg

Specimen Labels

According to JADG (1998) watasei lives in the soil of glossy-leaved evergreen forests. Choi et al. (1985) report the presence of P. watasei in the Korean peninsula. (Baroni Urbani and de Andrade 2003)

At a Glance • Larval Hemolymph Feeding  



A member of the pergandei clade. Outgroup of Proceratium compitale and Proceratium creek but differing from both species, in the worker and gyne, by the first funicular joint 1/3 longer than broad instead of 1/2 longer than broad, by the funicular joints about as long as broad instead of longer than broad and by the gastral tergite I strongly round on the curvature instead of slightly angulate. (Baroni Urbani and de Andrade 2003)

Keys including this Species


Distribution based on Regional Taxon Lists

Palaearctic Region: Democratic Peoples Republic of Korea, Japan (type locality), Republic of Korea.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


Very little is known about the biology of Proceratium ants. They nest in soil, rotten wood, under deep-set stones and, in a few cases, tree branches. For many species the nest consists of small rounded chambers hollowed out of soft rotten wood or in the soil. Toward the cooler limits of the range, particularly in North America, nests and foraging workers are found under deep set rocks instead of in rotten wood. The nest site is usually in forest shade, in old moist gardens, or similar habitats that are constantly moist. Some species of known to be egg predators of arthropods, especially of spiders.

Most Proceratium are relatively rare but this is not the full explanation for why they are not commonly collected. Colonies of most species are small. Based on anectdotal natural history information from a few species, it was once thought that most Proceratium would likely be found to have mature colonies that contain somewhere between 10 - 50 workers. Yet nests with more than 50, and in some cases up to 200, workers have been been reported. Besides small colonies, these ants also do not appear to forage in places where they are readily encountered.

Males and females are though to be produced in small numbers but we generally do not have enough data for colonies of any species to know what might be typical. Reproductive flights have been observered toward the end of the summer in some northern temperate areas. In these regions the nuptial flight occurs during the last half of August. Both sexes climb some distance from the nest entrance before taking flight. Workers too issue from the nest during the nuptial flight, as is often the case with otherwise cryptobiotic ants.



The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • watasei. Sysphincta watasei Wheeler, W.M. 1906c: 303, pl. 41, fig. 5 (w.q.) JAPAN. Ogata, 1987: 107 (m.); Onoyama & Yoshimura, 2002: 45 (m.). Combination in Proceratium: Brown, 1958g: 248. See also: Baroni Urbani & De Andrade, 2003b: 215.

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



Baroni Urbani and de Andrade (2003) - Head longer than broad, with sides subparallel in the two anterior thirds and strongly convex in the posterior third. Anteromedian part of the clypeus rectangular and strongly protruding anteriorly. Anteromedian part of the clypeus, dorsally, with a variably impressed inverted Y-shaped carina. Frontal carinae gently diverging posteriorly, slightly raised and not very close each other. Lateral expansions of the frontal carinae narrow. Head anterolaterally with a short, longitudinal carina. Genal carina absent. Gular area not impressed. Eyes small, composed by a dark dot below or whithin the integument. First funicular joint 1/3 longer than broad. Funicular joints 2-10 about as broad as long. Last funicular joint slightly shorter than the sum of joints 8-10. Scapcs 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 5-6 denticles before the pointed apical tooth. Palp formula 4,3.

Mesosoma about as long as or slightly longer than the head (mandibles included). Promesopleural and meso-metapleural sutures impressed ventrally only. Propodeal dorsum between basal and declivous faces slightly incised. Basal and declivous faces of the propodeum dorsally separated by a narrow lamella interrupted medially. Declivous face of the propodeum with a broad, semitransparent lamella on each side, the lamella slightly denticulate apically, broader on the posterior half. Propodeal spiracle round and over the mid height in lateral view.

Petiole convex in profile, with the sides diverging on the anterior third and strongly convex posteriorly in dorsal view. Anterior border of the petiole gently concave and carinate, the carina sometimes forming a denticle on each side. Ventral process of the petiole lamelliform, short and triangular. Postpetiole anteriorly as broad as the petiole; its sides diverging on the anterior half and gently convex on the posterior half. 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 round and slightly recurved forwards.

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 1/7 shorter than hind tibiae. Second tarsomere of hind legs longer than the pretarsus. Pretarsal claws simple. Arolia absent.

Sculpture. Head, mesosoma, petiole and postpetiole minutely reticulate-punctate sparsely and irregularly rugulose, the reticulation broader, deeper and resembling irregular foveae in some parts of the mesosoma, petiole and postpetiole. Gaster superficially shining and covered by minute, piligerous impressions. Legs punctate.

Body covered by hairs of three main types: (1) short, dense, subdecumbent on the whole body, sparse and suberect on the funicular joints; (2) longer than type (1), sparse and suberect on the whole body, absent on the funiculi; (3) shorter than hair type (1), dense and decumbent on the funicular joints only. In addition the funicular joints bear whitish, thick, appressed, short, sparse hairs, and the scapes with sparse hairs similar to type (2) but shorter.

Colour dark fesrugineous.

Measurements in mm and Indices: TL 4.68-5.20; HL 1.04-1.12; HW 0.87-0.96; EL 0.03-0.04; SL 0.81-0.89; WL 1.32-1.44; PeL 0.41-0.48; PeW 0.37-0.41; HFeL 0.96-1.08; HTiL 0.81-0.90; HBaL 0.68-0.80; LS4 0.39-0.41; LT4 1.08-1.22; CI 83.6-85.7; SI 78.0-79.5; IGR 0.34-0.36.


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

Mesosoma robust. Scutellum as long as the sides of the basal face of the propodeum; its lateral parts gently converging into a convex posterior border. Metanotum without denticle. Propodeal lamellae dorsally connected.

Fore wings of our type 1, hind wings of our type 2 as defined in the description of the genus.

Measurements in mm and Indices: TL 5.60; HL 1.16; HW 1.00; EL 0.16; SL 0.91; WL 1.62; PeL 0.48; Pew 0.46; WFeL 1.14; HTiL 0.95; HBaL 0.83; LS4 0.55; LT4 1.46; CI 86.2; SI 78.4; IGR 0.38.

Type Material

Baroni Urbani and de Andrade (2003) - Worker and gyne. Type locality Okayama (Bizen) and Kamakaur (Sagami Gulf), Japan. Type material 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 215, fig. 90 worker described)
  • Brown, W. L., Jr. 1958g. Contributions toward a reclassification of the Formicidae. II. Tribe Ectatommini (Hymenoptera). Bull. Mus. Comp. Zool. 118: 173-362 (page 248, Combination in Proceratium)
  • Ogata, K. 1987a. A generic synopsis of the poneroid complex of the family Formicidae in Japan (Hymenoptera). Part 1. Subfamilies Ponerinae and Cerapachyinae. Esakia 25: 97-132 (page 107, male described)
  • Onoyama, K. ; Yoshimura, M. 2002. The ants of the genus Proceratium (Hymenoptera: Formicidae) in Japan. Entomol. Sci. 5(1): 29-49 (page 45, male described)
  • Wheeler, W. M. 1906h. The ants of Japan. Bull. Am. Mus. Nat. Hist. 22: 301-328 (page 303, pl. 41, fig. 5 worker, queen described)