Kempf, W. W., 1966, A revision of the Neotropical fungus-growing ants of the genus Cyphomyrmex Mayr. Part II. Group of rimosus (Spinola) (Hym. Formicidae)., Studia Entomologica (N. S.) 8, pp. 161-200: 161-165
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Group of Cyphomyrmex rimosus
The rimosus-group has previously (Kempf, 1962: 30; 1964: 4) been defined by the ensemble of the following characters in the worker (and female) caste: Mandibles with 5 teeth only; two or no midpronotal tubercles present; preocular carina either curving mesad above eyes (most species of the group) or fading out above eyes, yet with the postero-lateral border of the antennal scrobe more or less defined as in the strigatus-group ( longiscapus HNS , wheeleri HNS , costatus HNS and presumably also flavidus HNS ). Following is a list of the presently recognized forms, including the not yet analyzed infraspecific forms of rimosus HNS and several new synonyms (W = worker; F = female; M = male):
The rimosus-group is much more widely distributed than the strigatus-group, ranging from southern U.S.A. both over the Antilles and Central America south to central Argentina. Yet only rimosus HNS with its puzzling "races" and morphs occupies the entire range of the territory (except for northeastern Brazil!), whereas the remaining species are seemingly rather restricted in their distribution. The group reaches its highest degree of diversity and endemism in northern South America and in Central America.
Most of the collected material, over 90% of the total, belongs to the ubiquitous rimosus HNS s. L, whose striking variability is still not understood and had to be left out for a future study. Yet a slight improvement is introduced here by raising dentatus HNS , hamulatus HNS and transversus HNS to full specific rank.
In short, the presently proposed arrangement, while exhausting the best of my possibilites and efforts, is not to be considered as final. Only more copious material and a better knowledge of the variability, distribution and biology of all forms will permit to raise our knowledge of the Cyphomyrmex HNS ants to a satisfactory level.
Bionomics. - With the exception of a few well studied species, such as rimosus minutus Mayr HNS (Weber, 1955) and costatus Mann HNS (Weber, 1957a), very little, if any, information is available for most forms. One fact, however, regarding the fungi cultivated by these ants, has become firmly established in the meantime. Whereas some species ( costatus HNS and wheeleri HNS ) grow a basidiomycete fungus of the family Agaricaceae, which under the care of the ants forms bromatia of loosely clustered hyphal swellings or gongylidia (fungus garden of the flocculent type), other species ( rimosus HNS , dentatus HNS , transversus HNS ) cultivate bromatia consisting of polygonal solid masses of cells of a yeastlike fungus, which Wheeler (1907: 772) named Tyridiomyces formicarum, but so far has not been truly identified.
It is interesting to note that in the aforesaid species the difference in type of fungus and bromatia coincides with a morphological difference, shown by the development and direction of the preocular carina and the postero-lateral limit of the antennal scrobe; in costatus HNS and wheeleri HNS the preocular carina fades out above the eye, but the postero-lateral limit of the scrobe behind the eye is somehow indicated, whereas in rimosus HNS and allies the preocular carina curves strongly mesad above the eye, and there is no proper postero-lateral limit to the scrobe. Only future research will show whether or not this relationship is constant and may be generalized.
Key to the species for workers
1. Antennal scrobe reticulate and quite shining; preocular carina not curving mesad above eye, postero-lateral limit of antennal scrobe marked at least by difference of sculpture (Figs. 2, 19)........ 2
- Antennal scrobe densely but indistinctly granulate and opaque; preocular carina curving mesad above eye, the postero-laferaj border of scrobe being formed by another carina (if present), which arises from the occipital corner and extends foreward to the inferior or posterior border of eye, never joining the preocular carina (Figs. 3, 6, 11)..................................................... 4
- Antennal scape not surpassing occipital corners when in repose; lateral pronotal tubercles developed; cheeks marginate below.... 3
3. Disc of tergum I of gaster with a pair of strong longitudinal carinae (Fig. 19); midpronotal tubercles absent; postero-dorsal margin of petiole not drawn out nor bidentate (Fig. 38) .... 4. costatus Mann HNS
- Disc of tergum I of gaster lacking a pair of longitudinal carinae; midpronotal tubercles present (Fig. 25); postero-dorsal margin of petiole drawn out as a foliaceous bidentate lamina (Fig. 37) .... 2. wheeleri Forel HNS
4. Antennal scapes not surpassing the strikingly auriculate occipital lobes (Figs. 4, 5); pronotum completely unarmed (Figs. 23, 26), its sides marginate only ....................................... 5
- Antennal scapes usually surpassing the scarcely or gently drawn out occipital lobes; pronotum with the lateral tubercles always present.. 6
5. Anterior mesonotal tubercles conical, posterior ones low and tumuliform(Fig. 23); petiolar node much less than thrice as broad as long (Fig. 33)................................. 5. bicornis Forel HNS
- Thorax completely unarmed, its dorsum in profile evenly rounded (Fig. 26); petiolar node strikingly transverse, thrice as broad as long (Fig. 32) .............................. 6. laevigatus Weber HNS
6. Paired midpronotal tubercles absent ........................... 7
- Paired midpronotal tubercles' present ........................... 9
- Hind femora dilated and ventrally carinate at basal third (Figs. 46| 50); funicular segments II-VIII about as long as broad ........ 8
- - Epinotum dentate; basal face laterally marginate to carinate (Fig. 21); antennal scapes scarcely projecting beyond tip of occipital corners (Fig. 8) ............................. 9. dentatus Forel HNS
9. Maximum expansion of frontal carinae less than interocular width (Fig. 6); thorax finely but distinctly rugose; lateral. pronotal and anterior mesonotal projections long and spine-like (Fig. 14) .... 10. foxi Forel HNS
- Maximum expansion of frontal carinae exceeding interocular width; thorax lacking distinct rugulae; lateral pronotal and anterior mesonotal projections short, tubercular or at best conical ...... 10
10. Apex of occipital lobes drawn out into a spine (Figs. 1, 3); anterior mesonotal tubercles high and conical (Figs. 15, 16) ...... 11
'- Apex of occipital lobes not drawn out into a spine; anterior mesonotal tubercle low and usually tumuliform ................ 12
11. Body without appressed scale-like hairs; basal face of epinotum sharply carinate in its entire length; posterior mesonotal tubercles low, not tooth-like (Fig. 15) ................ 11. vorticis Weber HNS
12. Petiole strikingly transverse, thrice as broad as long (Fig. 30); postpetiole discally deeply and broadly impressed; body hairs thickly squamous .................................. 14. transversus Emery HNS
- Petiole narrower, not thrice as broad as long (Fig. 39); postpetiole with a shallower middorsal impression; body hairs finer ...... 13
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