Crematogaster carinata Mayr
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|Crematogaster carinata Mayr|
Crematogaster carinata Mayr HNS , 1862:768. Syntype workers: Brazil, Rio de Janeiro (Novara) [ NMW, MCSN] (examined, NMW worker here designated LECTOTYPE) . Emery, 1922:136: combination in C. (Orthocrema) HNS .
Crematogaster limata r. parabiotica Forel HNS , 1904b:683. Syntype worker: Colombia, Magdalena, Orihueca , parabiotic with Dolichoderus debilis HNS (coll. Forel) [ MHNG] (examined, worker here designated LECTOTYPE) . Forel, 1912:217: description of queen. Emery, 1922:136: combination in C. (Orthocrema) HNS . Wheeler, W.M. 1921b:152; Wheeler, W.M. 1923:3; Kutter, 1931:61; Santschi, 1939:161; Kempf, 1972:88: subspecies of limata HNS . NEW SYNONYMY
Costa Rica to Brazil (Rio de Janeiro), Bolivia.
Description of worker
Color red brown; mandibles, antennal club, and tarsi usually lighter yellow; workers monomorphic in size.
Mandibles smooth and shining; clypeus usually with 5-6 longitudinal carinulae, these may be more abundant, making clypeus uniformly striate, or they may be nearly absent, making clypeus smooth and shining, especially medially; head about as long as wide, subquadrate, with emarginate posterior border; antenna with distinct two-segmented club, or third segment from end somewhat enlarged, blurring distinction between two and threesegmented club; scapes with abundant long erect setae; when scapes laid back from antennal insertions, they slightly surpass margin of vertex; face largely smooth and shining, with variable extent of striated region between antennal insertion and eye, and whorled above antennal insertion; face covered with abundant long flexuous white setae, no appressed pubescence; in face view abundant setae project from lateral and posterior margins.
Promesonotum in profile forming evenly convex surface, varying from flattish to forming peak at juncture of pro and mesonotum; propodeal suture deep in dorsal view but obscured in profile due to lateral carinulae that bridge the suture; posterior mesonotum curves smoothly into horizontal dorsal face of propodeum; propodeal spines short, projecting posteriorly such that they are more or less in same plane as dorsal face of propodeum; dorsal and posterior face of propodeum appear well differentiated in lateral view, the dorsal face confluent with the horizontal spines, the posterior face sloping down to petiolar insertion, but faces less differentiated medially; pronotal dorsum with variably developed longitudinal carinulae, strongest laterally, becoming weaker medially, interspaces smooth and shining; mesonotal dorsum with two strong, subparallel lateral carinae, interspace smooth and shining or with faint longitudinal carinulae; dorsal face of propodeum striatorugose, rugulae extending onto spines, posterior face smooth and shining; side of pronotum smooth and shining; katepisternum and ventral portion of side of propodeum variously punctatorugose; dorsal portion of side of propodeum smooth and shining; mesosomal dorsum with abundant long flexuous white setae, setae on pronotal humeri longest; femora and tibiae with abundant long erect setae.
Petiole in side view subtrapezoidal, varying in length and degree of narrowing anteriorly, weakly punctate to nearly smooth; anteroventral tooth well developed, often forming a right-angle to short acute tooth; dorsal face of petiole smooth and shining, elongate, widest posteriorly, regularly tapering anteriorly, with a long flexuous seta on each posterolateral tubercle and varying number of short setae along posterior border; postpetiole lacking ventral tooth, globular in dorsal view, with abundant erect setae; fourth abdominal tergite smooth and shining, with abundant long flexuous erect white setae, no appressed pubescence.
HL 0.561, 0.528, 0.657; HW 0.604, 0.563, 0.722; HC 0.565, 0.507, 0.664; SL 0.485, 0.512, 0.612; EL 0.130, 0.139, 0.175; A11L 0.215; A11W 0.101; A10L 0.113; A10W 0.089; A09L 0.068; A09W 0.064; A08L 0.051; A08W 0.051; WL 0.615, 0.585, 0.744; SPL 0.077, 0.109, 0.148; PTH 0.148, 0.137, 0.166; PTL 0.207, 0.213, 0.250; PTW 0.144, 0.138, 0.174; PPL 0.169, 0.129, 0.178; PPW 0.162, 0.119, 0.166; CI 108, 107, 110; OI 23, 26, 27; SI 86, 97, 93; PTHI 71, 64, 66; PTWI 70, 65, 70; PPI 96, 92, 93; SPI 13, 19, 20; ACI 0.64.
A normal queen (dorsal face of propodeum drops steeply from postscutellum and much of propodeum appears ventral to scutellum and postscutellum, Fig. 1) with general shape, sculpture, and pilosity characters of the worker; size characters as in Figures 4 and 5.
Crematogaster carinata HNS is a biologically complex species and there is almost certainly some degree of genetic structuring that is not readily revealed by external morphology. This species and its close relative C. levior HNS often have large polygynous colonies that blanket large sections of forest, with various degrees of mutual foraging and nesting with other unrelated ant species. Forel observed this species nesting with Dolichoderus debilis HNS in Colombia, and coined the term parabiosis for the mutual sharing of nest space and foraging columns by multiple species (Forel 1898). Further examples of parabiosis involving carinata HNS (as parabiotica HNS ) were described by Wheeler (1921a).
In the Atlantic lowland forests of northeastern Costa Rica, including coastal strand vegetation, C. carinata HNS forms large polygynous, perhaps even unicolonial colonies. Columns of workers are spread over second growth vegetation and multiple crowns of trees, with small clusters of physogastric queens, brood, and workers dispersed in dead twigs and branches and under epiphytes. There is no obvious colony center, and it is difficult to discern colony boundaries. At La Selva Biological Station it is one of the most common species in the canopy. It occurred in 24 of 52 canopy fogging events. In an old treefall I once found a small aroid with a carinata HNS nest in and around the root ball. The ants had covered the roots with a mass of carton material to form a nest volume about the size of a large orange. Inside were abundant workers, brood, and 43 dealate queens. Some of these queens had torn remnants of wings, suggesting they never left the nest for a nuptial flight and perhaps never mated. In general when multiple queens are found in nests they are evenly distributed in the nest volume, individually or in pairs. Brood is segregated by size. I observed a similar occurrence of large polygynous colonies in the Santa Marta region of Colombia, the same site as Forel's original observations of parabiosis. In contrast to these observations of polygyny, discrete nests with single physogastric queens seem to be the rule in the Pacific and southeastern Atlantic lowlands of Costa Rica, and at some sites in Venezuela.
On occasion I find aggregations of workers only, with no brood. All the dead sticks in a patch of forest understory will be filled with workers. The nest aggregation will be bounded, with all nests within about a meter of each other, but no colony center or area with brood can be found.
In different parts of its range, in both polygynous and monogynous forms, Crematogaster carinata HNS may form parabiotic associations with other ants. In the La Selva forest canopy it cohabits large ant gardens with Odontomachus panamensis HNS . Because the ant gardens are conspicuous and packed with Crematogaster HNS workers and brood, it can appear that the Crematogaster HNS are a specialized associate with Odontomachus HNS , but closer inspection reveals that the ant gardens are nodes of higher Crematogaster HNS density in a sea of thinly spread Crematogaster HNS nests. It is possible that the ants in Odontomachus HNS nests are genetically and behaviorally differentiated from those in the diffuse polydomous colonies, but I have not found any evidence for this based on external morphology.
In the Pacific lowlands of Costa Rica I have twice seen parabiotic associations between carinata HNS and Dolichoderus HNS species. At Carara I observed a parabiotic association between carinata HNS and D. debilis HNS . Several nests were in a cluster of dead branches. Crematogaster HNS workers and brood were distributed in multiple chambers, and one chamber contained a single physogastric queen. The nests of the two species were contiguous and interdigitated, with interconnections among chambers, but they were still largely segregated. In general the Crematogaster HNS occupied smaller and more peripheral chambers, while the Dolichoderus HNS occupied larger chambers in the center of the branches. In some peripheral chambers I found workers of both species together, but these chambers never contained brood. Any chamber with brood always contained only one species. In Corcovado National Park I observed parabiotic foraging involving carinata HNS and D. inermis Mackay HNS . Workers of both species were using the same foraging trails, and both species occurred together in clusters of non-foraging workers. Davidson has multiple observations of parabiotic foraging between carinata HNS and D. debilis HNS in Peru (pers. comm.), and many similar observations are reported by Forel (1898) and Wheeler (1921a).
Wherever I have observed carinata HNS it makes use of carton construction to a variable extent. Construction may be as small as a 2cm diameter shelter over a single scale insect. Several times I have seen a 5-10cm wide globular mass of carton extending from the end of a rotten stick or investing epiphyte roots, extending the nest volume. In very humid areas these small carton nests may sprout epiphyte seedlings and in some cases form small ant gardens. Workers form large and more fully developed ant gardens only when in the presence of a larger parabiotic associate.
Workers may be found foraging day or night, and they are generalized omnivores. I have seen them scavenging dead or wounded insects, they recruit to carbohydrate and protein baits, and they are frequent visitors at extrafloral nectaries.
Costa Rican species in the limata HNS complex are brasiliensis HNS , carinata HNS , limata HNS , and tenuicula HNS . All have abundant erect flexuous setae on the face, moderate length to short posteriorly directed propodeal spines, and elongate tapering petioles. The four species can be difficult to separate. They differ primarily in the nature of the ventral processes of the petiole and postpetiole. Crematogaster carinata HNS has a squared-off anteroventral petiolar process and no postpetiolar process. Both brasiliensis HNS and tenuicula HNS have ventral postpetiolar processes. Crematogaster limata HNS usually lacks a petiolar process but can be very like carinata HNS in some cases. Crematogaster limata HNS is a larger ant with longer propodeal spines. Crematogaster carinata HNS may also be confused with foliocrypta HNS , but foliocrypta HNS has appressed rather than erect tibial pilosity.
Crematogaster carinata HNS is also very similar to the South American species Crematogaster levior Longino HNS (see Miscellanea). The two species are not cleanly separable on morphological grounds. In this revision I have restricted C. levior HNS to a specialized parabiotic associate of Camponotus femoratus (Fabricius) HNS . Crematogaster levior HNS and Camponotus femoratus HNS inhabit ant gardens throughout Amazonian South America. All Crematogaster HNS material collected from these ant gardens has the worker pronotum completely smooth and shining. In contrast, I have identified as carinata HNS all material with longitudinal carinulae on the pronotum. However, on purely morphological grounds there is continuous variation from strongly carinate forms, to forms with faint traces of carinulae, to the completely smooth pronotum of levior HNS . Crematogaster levior HNS is polygynous and polydomous like some populations of carinata HNS . Crematogaster levior HNS is always parabiotic with Camponotus femoratus HNS , while C. carinata HNS is facultatively parabiotic with other large ants in the genera Dolichoderus HNS and Odontomachus HNS .
Further evidence for separate species has been found by D. Davidson at her study site at Cocha Cashu Biological Station in Amazonian Peru. In early studies of ant gardens and their ants (Davidson 1988, Seidel et al. 1990, Davidson et al. 1990) I helped identify the Crematogaster HNS and I failed to differentiate levior HNS and carinata HNS . More recent observations on behavior and defensive chemistry suggest discrete sympatric forms, with levior HNS inhabiting ant gardens with Camponotus HNS and carinata HNS found outside those gardens (Davidson pers. comm.). Davidson has discovered that levior HNS has lost its chemical defense and instead relies on the defensive capabilities of C. femoratus HNS . In contrast, carinata HNS has retained chemical defenses. Reflecting the differences in defensive chemistry, levior HNS does not elevate the gaster when disturbed; carinata HNS does. Crematogaster carinata HNS is often found living parabiotically with Dolichoderus debilis HNS , and in this case it is the Dolichoderus HNS that has lost its chemical defense, relying on the Crematogaster HNS . Davidson's observations on carinata HNS in Peru not withstanding, one should not assume that carinata HNS exhibits the same behavior and defensive chemistry throughout the range. It would be worth investigating whether carinata HNS at La Selva Biological Station, which lives in ant gardens with the aggressive species Odontomachus panamensis HNS , exhibits behavior and chemistry more like levior HNS . In contrast, the carinata HNS from Costa Rica's Pacific slope, which is monogynous and parabiotic with non-aggressive Dolichoderus HNS , might be like Peruvian carinata HNS .
Forel's brief description of parabiotica HNS was followed by a list of specimens: Colombia, Magdalena, Orihueca, parabiotic with Dolichoderus debilis (Forel) HNS ; Para ( Göldi); Costa Rica (Pittier); and Brazil, Amazonas, Jurua, Jurua Miry, among leaf bases of Tillandsia HNS No. 5734 (Ule). I examined the Colombian and Ule's Brazilian material under parabiotica HNS at MHNG. The Colombian material had carinate pronota and matched my collections from the Santa Marta area. Ule's Brazilian material, probably from ant gardens, had smooth pronota. Forel's published description of parabiotica HNS suggested that the Ule specimens might be a separate variety. Among the specimens at MHNG a worker from Orihueca has "typus" written on the label. Other labels have "cotypus" or no indication of type status. It appears that Forel based the description primarily on the Colombian material and I am forced to treat the Orihueca specimen as the lectotype of parabiotica HNS and synonymize it under Mayr's carinata HNS . The Ule specimens I identify as levior HNS . Following this hypothesis of species boundaries, Wheeler's (1921a) discussion of parabiosis included observations of carinata HNS living parabiotically with Dolichoderus HNS , and levior HNS living parabiotically with Camponotus femoratus HNS .
Within carinata HNS , there is pronounced variation in the degree of anterior narrowing of the petiole in side view, strength of pronotal carinulae, size of propodeal spines, and some details of queen size and petiole shape. Crematogaster levior HNS is more likely to be a "good" species, in terms of phylogeny and/or genetic similarity. Crematogaster carinata HNS , with its greater geographic range and morphological variability, is more likely to be a set of allopatric or parapatric species, or even a set of broadly sympatric cryptic species.
Austria, Wien, Naturhistorisches Museum Wien
Italy, Genova, Museo Civico di Storia Naturale "Giacomo Doria"
Switzerland, Geneva, Museum d'Histoire Naturelle
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