Cyphomyrmex longiscapus Weber

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: 165-167

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Cyphomyrmex longiscapus Weber


1. Cyphomyrmex longiscapus Weber  HNS 

(Figs. 2, 18, 29, 45)

Cyphomyrmex longiscapus Weber  HNS  , 1940: 410 (Worker; Colombia: Rio Porce). - Kempi, 1904: 4.

Types. - Several workers, collected at an altitude of 1020 m (3400') by Prof. N. A. Weber; 3 specimens seen.

Worker (lectotype). - Total length 3.7 mm; head length 0.91 mm; head width 0.67 mm; thorax length 1.23 mm; hind femur length 1.17 mm. Fuscous brown; appendages lighter. Integument of body and appendages densely and sharply reticulate-punctate; body with densely distributed foveolae, which are rather difficult to see on account of the microsculpture, extending equally over both pits and intervals.

Head as shown in Fig. 2. Mandibles longitudinally striolate, strikingly elongate. Clypeus with prominent and strongly convex, mesially vestigially notched, anterior apron; postero-mesially, in front of each anterior corner of frontal lobes, a vestigial tooth. Frontal lobes very little expanded laterad, continued posteriorly by the nearly straight, subparallel, strongly carinate, frontal carinae, which attain the triangular occipital lobes. Vertex with a pair of strong carinae. Preocular carinae fading out at level Of eyes, not curving mesad nor prolonged caudad. Antennal scrobe neatly differentiated in its posterior half from the cheeks by the absence of coarse pits. No supraocular tumulus. Eyes strongly convex with about 7-8 facets across their greatest diameter. Cheeks immarginate below. Occiput prolonged into a low, collarlike prominence around foramen. Scapes elongate-clavate, projecting beyond the occipital lobes by a distance exceeding twice their maximum width. Funicular segment I very long, subequal to 1I-IV combined; segments II-IX distinctly elongate.

Thorax as shown in Fig. 18. Pronotum completely unarmed, lacking also lateral carinae on disc; antero-inferior corner obtusely dentate. Mesonotum with two pairs of rather strong tubercles. Mesoepinotal constriction present. Epinotum completely unarmed; spiracle on a slight prominence. Legs rather long and thin; hind femora (Fig. 45) not dilated ventrally on basal third; posteroventral border vestigially carinulate.

Pedicel as shown in Figs. 18 and 29. Petiolar node, as seen from above, one and a half times as broad as long, its anterior corners broadly rounded; lacking dorsal carinae and tumuli. Postpetiole with an oblique anterior face nearly at right angle to the dorsal face; the latter with a pair of approximated small tubercles on anterior corners, another pair, blunter, stronger and more widely separated, on posterior corners; posterior border between tubercles slightly excised. Anterior border of first gastric tergum and sternum marginate; sides of tergum I practically immarginate.

Pilosity inconspicuous, consisting solely of fine, thin, silvery, decumbent hairs.

Female (cf. below) and male unknown.

Specimens examined: 3 workers taken by N. A. Weber at Rio Porce, Cordillera Central, Colombia, 3400 feet, Nov. 1938 (NAW n. 1088), lectotype (NAW) and paratypes (MCZ, WWK).

Discussion. - The present species, still known only from the type series, is highly distinctive both in general aspect (elongate head, mandibles and scape) and in several features not shared by any other known species of the group: the long mandibles, the scarcely expanded frontal lobes, the neck-like collar on occiput, and above all the configuration of the antennal scrobe which, although lacking the posterolateral limit of a postocular carina, is nevertheless similar to that of the strigatus-group. Fore the preocular carina does not curve mesad above eyes, and the postero-lateral limit of the scrobe is indicated by a difference in sculpture. The dentition of the mandibles, however, is of the rimosus-group, i. e. consisting of only five teeth.

There is no close relative for this species, even though wheeleri  HNS  and costatus  HNS  have the same reticulate-punctate sculpture of the antennal scrobe, and their preocular carina likewise does not curve mesad above eyes; wheeleri  HNS  , in addition, even possesses the reticulate-punctate sculpture of the integument of body and appendages.

Note. - Although basically resembling, 1 hesitate in definitely ascribing to the present species a lone worker and female, taken by W. L. Brown, Jr. and E. S. McCluskey on Barro Colorado Island, Panama Canal Zone, in January 1960 (n. B-55), on account of the following aberrant features:

Worker. - Decidedly smaller than type: total length 3.0 mm; head length 0.72 mm; head width 0.56 mm; thorax length 1.01 mm; hind femur length 0.82 mm. Reticulate-punctate body sculpture more superficial, hence the integument is shinier. Mesonotum having only the anterior pair of tubercles developed, the rest being flat. Mesoepinotal impression obsolete. Hind femora ventrally lobate and carinate on basal third. Petiole and postpetiole slightly broader (6:9 and 11:10), the latter with a deeper middorsal impression, stronger posterior paired tubercles, which project beyond the mesially deeply excised posterior border.

Female. - Total length 3.8 mm; head length 0.88 mm; head width 0.69 mm; thorax length 1.22 mm; hind femur length 0.98 mm. Similar to the worker. Pronotum unarmed, with humeral angles only feebly marked. Mesonotum: scutum flat, notauli present, no Mayrian furrows. Scutellum posteriorly weakly excised. Epinotum practically lacking a basal face, completely unarmed. Petiole and postpetiole similar to those of worker.

We need more material to decide whether these specimens represent a discrete form or just an extreme variant of longiscapus  HNS  .