Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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| Range | Diagnosis | Additional Images | Natural History | Synonymy | Types | Systematics | Material Examined |
Mexico to Venezuela. Range Map.
Face sculpture shallow, a highly variable combination of rugae and foveae (see below); frontal carina ends on dorsum of torulus, well separated from lateral clypeal carina; eye shallowly convex; vertex margin entire, not explanate; vertex flat, with longitudinal striae of variable strength (see below) radiating perpendicularly from occipital carina; HW 1.2-1.3mm (n=6); propodeal suture impressed but not breaking sculpture; face with sparse (fewer than 20) short, stiff, erect setae; mesosmal dorsum and AT4 with similar sparse setae, more abundant and flattened posterior to petiolar insertion; AT4 finely striate, ASW 0.018mm (n=1).
In Mexico and Central America, the face sculpture is dominated by irregular rugae, these crosslinked and bowed to form "incipient" foveae (SEM of face above shows this condition). These partially formed foveae may be in the form of irregular polygons laterally. Rugae vary in thickness, and on many specimens the foveae become more defined and teardrop shaped. In a few specimens from southern Costa Rica, the rugae become somewhat thickened and flattened, with conspicuous microarolate sculpture, and thus approaching the condition seen in Colombian and Venezuelan specimens. The vertex is shiny, and the longitudinal rugae are usually thin, widely spaced, somewhat irregular, and at times nearly absent.
In Colombia the striae are thickened, flattened, and nearly fused, isolating smaller, well-formed, teardrop-shaped foveae. The areolate microsculpture is more pronounced on the fused and somewhat flattened rugae, giving the face a granular to silky appearance, less shiny than most Mexican and Central American specimens. The vertex is similar to Central American material.
Venezuelan specimens have the face sculpture the same as Colombian specimens. In contrast to Central American and Colombian specimens, vertex has dense, regular, pronounced longitudinal striae.
The worker and queen are thoroughly described by Kempf 1951, the male by Snelling (1968).
Worker: lateral view (reduced, original); face view (reduced, original); face view, SEM (reduced, original); torulus, SEM (reduced, original); mesosoma, dorsal view, SEM (reduced, original); mesosoma, lateral view, SEM (reduced, original); petiole, lateral view, SEM (reduced, original); postpetiole, lateral view, SEM (reduced, original); postpetiole, dorsal view, SEM (reduced, original); gaster, dorsal view, SEM (reduced, original).
Procryptocerus scabriusculus is a frequently encountered species of Procryptocerus in Central America. Unlike most species, P. scabriusculus is most often found in dry habitats, roadsides, and second growth vegetation. Nest sites appear to be ephemeral, in dead stems, although nests have been found in live stems. Many of the specimens at USNM were on orchid plants intercepted by inspectors at U.S. entry ports. The orchids were most often Oncidium and Cattleya, but this probably reflects the preferences of orchid enthusiasts rather than the preferences of P. scabriusculus. Skwarra (1934) describes five colonies, three of which were in dead wood, one in hollow twigs, and one in a reed (from Kempf 1951). The following data are extracted from field notes and specimen labels.
Ojo de Agua (Longino): remnant moist forest patch. Two monogynous nests were collected from the tips of vertical dead sticks. One stick also contained an additional lone queen in a chamber immediately below the nest.
Longino #2621: polygynous colony (three queens) in live branch of recent treefall.
Ward #6515: roadside vegetation, ex dead stalk of Spilanthes.
Ward #7816: roadside, ex dead weed stalk.
Ward #7822: roadside, ex dead twig Baccharis trinervis.
Wilson's Finca (Janzen): secondary forest, ex twig.
In quarantine from Guatemala, ex Oncidium wentworthianum, ex orchids.
Ward #3757: cloud forest, ex dead twig of woody liana.
Ward #7431: second growth rainforest, ex dead twig.
Ward #7349-3, #7349-4: rainforest edge, queens and males at light.
Xilitla (Creighton): in Acacia twig.
Ciudad del Maiz (Creighton): in Cecropia.
Ward #8915: thorn woodland, ex dead twig Ficus.
Ward #8933, #8949, #8953: three nests ex dead twigs.
In quarantine from Caracas, ex Cattleya mossiae.
Wheeler (1984) observed the behavioral repertoire of a captive colony of P. scabriusculus, and used the results to discuss the phylogenetic significance of behavioral traits within the Cephalotini. The study took place in central Costa Rica, and in the course of the study four colonies were examined. At least one of the colonies was polydomous, in a cluster of twigs from a Spondias tree, and three colonies were polygynous, with up to 27% of the adult population composed of queens.
Workers forage at dusk and/or nocturnally, queens and males occur at lights at night, and sexuals have been observed leaving the nest at night (Snelling 1968).
Procryptocerus striatus schmalzi var. scabriusculus Emery, 1894:198. Holotype (unique syntype) worker: Costa Rica, Palmares (Alfaro) [MCSN].
Procryptocerus adlerzi: Emery (nec Mayr) 1890:55 (misidentified worker: Costa Rica, Palmares).
Procryptocerus striatus scabriusculus: Forel, 1899:45 (name elevated to trinomen, thus made available).
Procryptocerus scabriusculus: Kempf 1951:89; Snelling 1968:1 (description of male).
I examined the type at MCSN in July, 1990.
The broad range of this species and the large gaps in its known distribution (e.g. no material from Panama, and gap between Colombian and Venezuelan populations) suggest it may not exhibit reproductive integration via gene flow, although the gaps may be due to undersampling. There is no known autapomorphy for the species. Thus, it may not satisfy the requirements of a biological or phylogenetic species concept. It is nearly identical to lepidus, which occurs in southeastern Brazil. Whether the similarity is due to convergence or shared ancestry is unknown. If due to shared ancestry, it is unknown whether the two species together constitute a monophyletic or paraphyletic taxon.
Multiple collections from each region reveal little within-region variation, and the shared characters (face sculpture for Venezuela and Colombia, vertex sculpture for Colombia and Central America) are relatively uniform. A possible phylogeny is (Central America (Colombia, Venezuela), with the face sculpture common to Colombia and Venezuela being apomorphic, and the vertex sculpture in Venezuela being autapomorphic.
This species shares with lepidus a highly variable face sculpture. In Costa Rica and Venezuela, regions for which I have personal observations, scabriusculus occurs in scrub habitats or road edges at midelevations. In these habitats it does not appear sympatric with other species of Procryptocerus. It is thus tempting to speculate that the high variability in sculpture is due to competitive release.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
Date of this version: 7 November 1997.
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