Procryptocerus mayri Forel 1899

Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

worker lateral view

worker face view

Image catalogue, Costa Rican worker (click here).

Image catalogue, worker, sem (click here).

Image catalogue, holotype worker mayri (click here).

Image catalogue, holotype worker reichenspergeri (click here).


Colombia, Costa Rica, Venezuela, Peru, Brazil(?). Range map for Costa Rica (figure).

Description of worker

Central America

Worker measurements (n=1, Costa Rica): HW 1.678 (range 1.309-1.532, mean 1.465, n=4), HL 1.585, SL 1.0452, EL 0.388, MeL 2.405, MeW 1.233, PrW 0.743, PrL 0.670, PrS 0.479, PrT 1.149, MTL 1.392, MFL 1.535, MFW 0.462, PtL 0.599, PtW 0.531, PpW 0.617, PtH 0.434, AL 2.106, AW 1.750.

Head subtriangular in outline, margin of vertex roughly straight; frontal carina extends onto clypeus, separated from and passing above torulus as a continuous flange; torulus trough lacking; face sculpture composed of high, sharp, well-spaced rugae; spaces between rugae smooth and shining; rugae often anastomosing to form polygons, with little longitudinal orientation (clathrate sculpture); this condition grades into increasing degrees of longitudinal orientation of rugae, especially anteriorly; rarely, rugae may be almost entirely longitudinal and subparallel; clypeus at level of antennal insertions bent ventrad; clypeus with prominent median longitudinal carina, flanked with 1-4 longitudinal carinae on each side; lateral carinae of variable strength; genae varying from longitudinally rugose to coarsely foveate/areolate; genal bridge longitudinally rugose; mandibles coarsely to weakly striate; eyes nearly symmetrically convex; scape flattened with thick lateral margin distally, becoming narrower and more terete basally, then flaring into a basal flange; broad flat surface of scape finely areolate, outer lateral margin with coarse rugae; margin of vertex obtuse, weak, obsolete medially; vertex shiny with coarse, longitudinal striae radiating from occiput (of highly variable strength).

Mesonotal lobes short, acute, upturned; propodeal suture broadly, shallowly impressed, not breaking sculpture; anterolateral propodeal lobes absent; degree of margination between dorsal and lateral faces of propodeum variable; length of propodeal spines variable; propodeal spines vary from pointing straight back to being widely divergent; pronotum reticulate rugose, coarsely areolate anteriorly; in some specimens rugae somewhat longitudinally parallel on mesonotum; dorsal face of propodeum reticulate rugose to longitudinally striate; posterior face of propodeum meeting dorsal face at obtuse angle; posterior face of propodeum varies from completely smooth and shining with one or two transverse striae between bases of propodeal spines, to mostly covered with coarse transverse striae; side of pronotum, katepisternum, and side of propodeum with coarse longitudinal striae; becoming irregular on anepisternum and near dorsolateral pronotal margin; posterior surface of forefemur entirely smooth and shining; outer surface of metatibia coarsely rugose.

Ventral margin of petiole flat to weakly concave, with low anterior right-angled tooth; anterodorsal face of petiole shiny with coarse to faint transverse striae (completely smooth in a few specimens); posterodorsal face areolate-foveate (weakly longitudinally rugose in some specimens); postpetiole with a long, gently sloping anterior face, a broad, rounded summit near the posterior margin, and a steeply sloping posterior face; ventral margin of postpetiole short, with a prominent, acute anterior tooth; dorsum of postpetiole coarsely foveate-rugose (weakly longitudinally rugose in some specimens); first gastral tergite smooth and shining, or occasionally with faint rugae anteriorly near petiolar insertion; first gastral sternite largely microreticulate, nearly smooth; second gastral tergite with faint, dense, granular sculpture.

Abundant flexuous setae on face, mesosomal dorsum (>20 on central area of promesonotum, not including those on lateral margins), petiole and postpetiole, and gaster; first gastral tergite with sparse, whitish pubescence under the erect setae, or lacking underlying pubescence; color shining black, legs black or occasionally red.

Lectotype worker

Worker measurements: HW 1.951, HL 1.789, SL 1.203, EL 0.481, MeL 2.556, MeW 1.370, PrW 0.931, PrL 0.624, PrS 0.486, PrT 1.11, MTL 1.606, MFL 1.707, MFW 0.535, PtL 0.617, PtW 0.521, PpW 0.593, PtH 0.490, AL 2.037, AW 1.890.

The type of P. mayri differs from Costa Rican material primarily by being larger. Also, the face is more uniformly striate, less clathrate. The legs are red.

Holotype of reichenspergeri

Worker measurements: HW 1.885, HL 1.825, SL 1.200, EL 0.482, MeL 2.553, MeW 1.400, PrW 0.993, PrL 0.701, PrS 0.472, MTL 1.601, MFL 1.690, MFW 0.534, PtL 0.589, PtW 0.572, PpW 0.648, PtH 0.521, AL 1.969, AW 1.960.

The type of P. reichenspergeri is nearly identical to the type of P. mayri, but the legs are black instead of red. Leg color seems to be variable within populations. The only locality data for P. reichenspergeri is "Brazil" on the label of the type. No other specimens of P. mayri have been recorded from Brazil, so this lone type specimen is something of a mystery.

Other South American material identified as P. mayri

The following specimens are all very similar to the type, with only slight differences in the degree of longitudinal versus clathrate sculpture on the face, and the color of the legs. Two specimens from Venezuela (Rancho Grande) have HW's 1.95mm and 2.12mm, and red legs. A specimen from Colombia, Dept. Valle, has HW 1.72 and black legs (two other specimens in this series are similar). One specimen from Colombia, Dept. Nari–o, has HW 1.748 and red legs. One specimen from Peru has HW 1.62 and dark red legs. The face sculpture on this specimen is somewhat shallower than the type.

Additional specimens from Colombia, Ecuador, and Peru begin to blur the distinction between P. mayri and other forms in this complex. Further work is needed in this region.

Variation in frontal carinae

On most P. mayri from Costa Rica, and the series from Valle Dept., Colombia, the portion of the frontal carina that curves mesad above the torulus is well separated from the torulus, and remains relatively elevated (and higher than wide) to the point where it joins or parallels the lateral clypeal carina. On a few Costa Rican specimens, the types of P. mayri and P. reichenspergeri, the specimens from Rancho Grande, Venezuela, and the specimen from Peru, the frontal carina tapers as it curves mesad, and becomes little more than a raised line, no higher than wide, that crosses the dorsum of the torulus and approaches the lateral clypeal carina.

See discussion of rudis group.

Description of queen (based on Costa Rican material):

Queen measurements (n=1, Costa Rica): HW 1.95, HL 1.78, SL 1.19, EL 0.47, MeL 2.88, MeW 1.69, MTL 1.59, PtL 0.72, PtW 0.58, PpW 0.71, PtH 0.55, AL 2.34, AW 2.04.

Characters of the head, legs, petiole, postpetiole, and gaster similar to worker.

Pronotum and anterior portion of mesoscutum coarsely areolate-foveate. On the posterior half of the mesoscutum, and on the scutellum the interspaces become increasingly aligned as longitudinal rugae between the foveae. Dorsal face of propodeum with a variable extent of the median area vermiculate-longitudinally rugose, lateral margins areolate-foveate. Dorsal half of posterior face with 3-4 strong transverse carinae, ventral half smooth and shining. Pronotal sculpture extends onto sides, grading into wavy longitudinal carinae. Most of katepisternum and side of propodeum longitudinally carinate. Ventral half of anepisternum longitudinally carinate or smooth, dorsal half areolate-foveate, like pronotum.

Based on separate collections of 6 P. mayri queens and 6 P. batesi queens, there is a sculptural difference between the two species. Queens of P. mayri have the ventral half of the anepisternum smooth or longitudinally carinate. Queens of P. batesi have the anepisternum entirely areolate-foveate, with at most a narrow ventral strip smooth or with 1-2 longitudinal carinae.

Natural History

In Costa Rica, Procryptocerus mayri and batesi are nearly always found together, and they are restricted to wet montane forest. They occur commonly in cloud forest habitats, reach their peak abundances between 1000 and 1500m, and drop out at lower elevations where other species of Procryptocerus become more abundant. The restriction to montane forest is vividly illustrated on the Osa Peninsula in southwestern Costa Rica. Most of the peninsula is well below 500m elevation, but a few ridges in the center attain 700m, where there is a very small patch of vegetation with the aspect of a cloud forest. In spite of nearly two year's experience at low-elevation sites on the peninsula, P. mayri and P. batesi were only found during a two-day trip to this cloud forest, where they were abundant on low vegetation. On Costa Rica's Atlantic slope, mayri and batesi are common above 1000m in Braulio Carrillo National Park, but 10km north, at La Selva Biological Station (50-150m), they have never been collected in spite of intense collecting effort over many years.

The following nest data are extracted from field notes. All are from Costa Rica.

Prov. Puntarenas, Rio Lagartos below Santa Elena de Monteverde (Longino): riparian forest patch along stream. An acanthaceous gangly shrub (probably Justicia) overhanging stream had scattered workers on it. Two nests were in the lower branches of the plant, and the entrances pointed downwards and were easily seen from below. One nest was 49cm long, entirely within a live, 14mm diameter branch, with a single, centrally located, circular entrance hole. The walls of the chamber were very smooth and clean. The second nest was in a live branch with a dead apex; 4cm of the nest in live stem, 52cm in dead. It had two lateral entrance holes 30cm apart. A third branch, near the previous two, had an externally visible entrance hole identical to those of the Procryptocerus nests, but the branch contained a populous Camponotus nest.

The entire contents of the two Procryptocerus nests were collected [first nest: 48 adult workers, 13 alate queens, 12 adult males, 15 queen pupae, 11 worker pupae, 5 prepupae, 12 large larve, 9 small larvae, a few eggs. second nest: 64 adult workers, 36 alate queens, 7 adult males, 32 queen pupae, 6 worker pupae, 5 prepupae, 29 large larve, 15 small larvae, a few eggs]. The nests contained workers, sexuals, and brood, but no colony queen, which suggests they were parts of a polydomous colony.

Prov. Puntarenas, Wilson Botanical Garden (Longino): On 28 Feb 1989 small saplings of Cecropia obtusifolia were examined along a river bank in forest. The apical internodes contained founding Azteca queens, but the lower internodes contained colonies of other genera, most commonly Procryptocerus mayri and Heteroponera panamense. Nests of Procryptocerus occupied single internodes, but some saplings contained more than one nest. The contents of six nests were recorded, and are reported below. A number of workers bore a peculiar pale patch on AT4, where the integument appeared thin, deformed, and weakly sclerotized.

Contents of Procryptocerus mayri nests in Cecropia obtusifolia saplings. Saplings were approximately 2m tall. One contained three nests, the rest contained one:

Colln. Number*  2397  2398  2399  2400  2401  2403
Sapling Number    1     1     1     2     3     4
Adult Workers    75    46    55    49    31    94
Dealate Queens    1     0     1     0     0     1
Adult Males       0     0     0     0     0     6
Brood             +     +     +     +     +     +
* Longino accession number.

Monteverde, 1340m (Longino): wet forest edge; lone queen in soft rotten stick lodged in vegetation; a Camponotus nest was in the same stick.

Longino #165: wet forest; nest containing workers, alate queens, males, and larvae in the live trunk of a tree sapling.

Longino #1062: wet forest; nest in live branch of melastome tree; entire nest collected; contained 11 workers, 5 worker pupae, 2 prepupae, 6 larvae, 2 eggs.

Ward #7831: roadside; nest in dead twig of Baccharis trinervis.

In summary, P. mayri nests in a variety of plant stems, most often live ones. Individual nests contain fewer than 100 workers, but the frequent lack of dealate queens in nests suggests polydomy. The small amount of brood relative to adult workers, and the absence of any signs of stored food, suggest a long-lived worker population with a low rate of worker production. The presence of queen pupae, callows, and fully sclerotized adults together in the same nest suggests a gradual production of sexuals, and probably their gradual release.

Types and Synonymy

Procryptocerus mayri Forel 1899:43. Lectotype worker: Colombia (Landolt) [MHNG]. Kempf 1951:103 (redescription of worker, designation of lectotype).

Paracryptocerus mayri reichenspergeri Santschi 1921:98 [lapsus for Procryptocerus]. Holotype worker: Brazil (Reichensperger) [NHMB]. Kempf 1951:105; Longino and Snelling 2002 (synonym of mayri).

Literature Cited

Page author:

John T. Longino, The Evergreen State College, Olympia WA 98505 USA.

Date of this version: 6 December 2002.

Previous versions of this page: 2 September 1998.
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