Cyphomyrmex salvini

A common species that occurs in the leaf litter in a wide range of mesic forest habitats.

Identification
Longino (2004): Mandibles with 5 teeth; preocular carina curving mesad toward frontal carina; antennal scrobe poorly defined; lateral vertex margins produced as acute teeth that project posterolaterally; pronotum with lateral and median tubercles.

This species may be part of a species complex (see the Costa Rica biology section).

Distribution
Guatemala south to Ecuador.

Distribution based on Regional Taxon Lists
Neotropical Region: Belize, Colombia, Costa Rica, Ecuador, Guatemala, Honduras, Mexico, Panama.

Habitat
In Costa Rica this species is widespread in wet to moist habitats, from the lowlands to cloud forest.

Costa Rica
Longino (2004) reports the following: This species occurs in wet to moist forest habitats throughout the country, from lowlands to cloud forest. It is by far the most common Cyphomyrmex species in wet forest leaf litter. It does not usually occur in more open habitats, where it is replaced in abundance by Cyphomyrmex rimosus. The nests are in between leaves in the leaf litter, in small pieces of rotten wood on the ground, and in rotten logs. Nests are also quite common in the subarboreal zone, in dead wood suspended in vegetation or under epiphytes, but usually within 2m of the ground. Nests may be partially or wholly constructed of accreted organic soil. Colonies are small, from tens to hundreds of workers. The few nests I have examined in their entirety have been monogynous; I have never seen a polygynous colony.

The center of the nest is the fungus garden, which usually contains two or three large caterpillar droppings and a few dozen fragments of dead insects. The dead insect parts are often brightly colored beetle elytra, and the workers appear to selectively harvest fragments that are very shiny or with metallic coloration. When exposed the nests look like small glittering piles of jewels, dotted with the green yeast-form fungus. Workers usually forage nocturnally and may be seen carrying over their head a caterpillar dropping or beetle elytron that is often several times their own size.

I observed a nest in Corcovado National Park that was a mass of accreted organic soil on the side of a tree about 1m high. The nest was 20x10cm, elliptical in outline, and 3-4cm thick, with numerous seedlings sprouting from the surface. The nest contained a single dealate queen. Inquilines and other nest occupants included one Rogeria tonduzi worker, isopods, millipedes, annelid worms, nematodes, unidentified insect larvae, mites, snails, and one each of 3 species of Staphylinidae. Another similar nest of accreted soil also contained a small nest of Neoponera unidentata.

Subarboreal nests of C. salvini can have spectacular panic evacuations in response to army ant raids. Individual workers, each carrying a larva, explode from the nest and may actually rain onto surrounding vegetation. The workers disperse and rest on leaf tips for a period of time before making their way back to the nest.

I have sometimes found larvae of C. salvini to be parasitized by Diapriidae. In Corcovado National Park I found a nest in flat chambers under the loose dorsal bark of a dead log. The area of the nest was roughly an ellipse 20x8cm. There were many alate queens, males, and over 100 workers. When I collected from the disturbed colony I noticed workers carrying large, blackened larvae. I later discovered that all these blackened larvae were larval skins covering developing diapriid parasitoids. All the healthy brood of the colony was white. I kept part of the colony alive and isolated some parasitized larvae. Seven to eight days later wasps emerged from both ant tended and isolated larvae. Each larva contained a single wasp. Wasps emerged by cutting a slit above the larval head capsule. I sent material to Lubomir Masner, who identified the wasps as genus Acanthopria.

Addressing the variability of this species within Costa Rica, Longino also adds: Cyphomyrmex salvini is almost certainly a complex of sibling species, or at least shows some degree of morphological sorting by microhabitat. At various times I have tried to split Costa Rican salvini into as many as six or seven morphospecies. In a lowland rainforest site like La Selva Biological Station, a relatively small form with short scapes is collected abundantly in Winkler samples of sifted leaf litter from the forest floor, but is almost never collected by searching for nests (middle worker images above, specimen code INBIOCRI002278772). In contrast, a larger form with longer scapes is rarely collected in Winkler samples, but is commonly found when searching for nests (top worker images, specimen code INBIOCRI001254199). These nests are usually in dead wood lying on top of the litter or in the subarboreal zone. This size difference is also reflected in the queens. It appears that these two forms partition the forest floor, one occurring below the leaf litter, the other just above it.

Some collections have a relatively enlarged promesonotum compared to others, and this form seems more abundant in mid-elevation sites.

The Monteverde cloud forest contains one common species of Cyphomyrmex, and it is an almost black, somewhat more wrinkled version of lowland salvini (bottom worker images, specimen code INBIOCRI001281765). There seems to be a fairly abrupt transition from the dark cloud forest form to lighter-colored and somewhat smoother forms just downslope in either direction. The form of salvini in the southern Pacific lowlands (Corcovado National Park and vicinity) is a bit different from either of the La Selva forms, appearing intermediate.

In spite of this degree of spatial patterning, all of the characters show overlapping distributions and I have given up trying to separate them for now.

Nomenclature

 * championi. Cyphomyrmex championi Forel, 1899c: 41, pl. 3, fig. 3 (m.) PANAMA. See also: Kempf, 1966: 192. Junior synonym of salvini: Snelling, R.R. & Longino, 1992: 492.
 *  salvini. Cyphomyrmex rimosus r. salvini Forel, 1899c: 40, pl. 3, fig. 2 (q.) PANAMA. Wheeler, W.M. 1907c: 724 (w.m.). Raised to species: Weber, 1958d: 261. Senior synonym of acutus: Kempf, 1966: 190; of championi: Snelling, R.R. & Longino, 1992: 492.
 * acutus. Cyphomyrmex acutus Weber, 1940a: 409 (diagnosis in key) (w.) PANAMA. Subspecies of salvini: Weber, 1958d: 261. Junior synonym of salvini: Kempf, 1966: 190.

Description
Kempf (1964) - Although resembling rather closely Cyphomyrmex vorticis salvini presents an even more intimate relationship with Cyphomyrmex rimosus, already shown by the fact that up to recently it had been considered just as a race of the latter. The larger size, the prominent tooth-like occipital corners, the salient supraocular teeth, the conical or spine-like mesonotal projections, the strongly developed ridges and impressions on head, the longer legs are the chief features that separate Cyphomyrmex salvini from rimosus.

Worker
Kempf (1964) - Total length 3.3-3.8 mm; head length 0.80-0.93 mm; head width 0.69-0.83 mm; thorax length 1.07-1.28 mm; hind femur length 1.01-1.17 mm. Close to the preceding vorticis, with the following differences:

Head (fig 3). Frontal lobes somewhat pointed cephalad, nearly straight and strongly diverging laterad, conspicuously rounded caudad. Frontal carinae either reach (as in rimosus) or do not reach (as in vorticis) the occipital lobe. Occiput rather perpendicular than oblique. Funicular segment I shorter than II and III combined.

Thorax (fig 16). Antero-inferior corner of pronotum forming an obtuse angle. Posterior mesonotal tubercles conical, although rather low, but not welt-like. Pair of longitudinal carinae on basal face of epinotum blunt, usually confined to the anterior half; when extending over posterior half then only vestigial. Oblique welt on sides of epinotum usually not well developed.

Petiolar node (fig 36) more strongly constricted behind, just in front of postpetiolar insertion. Median and lateral impressions in front of posterior border of postpetiole deeper, the paired tubercles, which separate these impressions, stronger.

Body hairs conspicuous, squamous, either appressed or recurved as on scapes and ventral borders of head and on legs.

Queen
Long 3.7 millim. Lobe antérieur des arêtes frontales fort grand, plus grand que chez le C. rimosus. Angles postérieurs de la tête prolongés en oreilles recourbées plus longues que chez le C. strigatus, mais bien plus courtes que chez le C. auritus. Le bord médian des arêtes frontales forme deux arêtes qui bordent l'épistome et l'aire frontale en forme de triangle. Chague ocelle est placé sur une élévation; celle des deux latéraux se prolonge en arête arquée vers l'angle postérieur de la tête. Le pronotum a devant, en haut, de chague côté une forte dent triangulaire. Le mésonotum a devant, en haut, au milieu, un disque arrondi et bordé; au milieu, en arrière de ce disque, deux arêtes longitudinales très obtuses, de côté un large feston. Le proscutellum a un feston de côté. Le scutellum est profondément échancré et bidenté. Le métanotum a deux très petites dents. Les deux noeuds du pédicule rectangulaires, plus larges que longs, le 2me beaucoup plus large. Abdomen très convexe, à peine subbordé, sans trace d'élévations ni de dépressions à sa surface. Mat. Microscopiquement raboteux; finement tuberculeux et rugueux. Tout le corps couvert, comme chez le C. rimosus, i. sp., d'une pubescence espacée, courte, épaisse, brillante et squameuse. D'un brun roussâtre ferugineux. Tête et abdomen bruns foncés. - Diffère du C. rimosus para ses oreilles et ses arêtes beaucoup plus fortes.

Type Material
Kempf (1964) - A lone dealate female, collected by Champion at Bugaba, Panama, presumably deposited in the British Museum (Natural History); not seen. Types of acutus in the Weber collection (NAW); not seen.