Cyphomyrmex cornutus, Kempf, W. W., 1968

Kempf, W. W., 1968, A new species of Cyphomyrmex from Colombia, with further remarks on the genus (Hymenoptera, Formicidae)., Revista Brasileira de Biologia 28, pp. 35-41 : 35-38

Cyphomyrmex cornutus sp. n.

Worker (holotype) - Total length 3.9 mm; head length 0.96 mm; head width 0.85 mm; maximum diameter of eyes 0.19 mm; scape length 0.88 mm; thorax length 1.31 mm; hind femur length 1.31 mm; petiole width 0.32 mm; postpetiole width 0.40 mm. Fuscous brown; mandibles, funiculi, bottom of sides thorax, middle and hind coxae, tarsi brown to testaceous brown; dorsum of head and gaster nearly black. Integument opaque; densely and minutely punctate-granulate.

Head as shown in Fig. 1. Mandibles finely longitudinally rugulose with the dentition of the " rimosus " type, i. e. 5 teeth with a broader diastema between second and third basal tooth. Clypeus with a narrow, flattened anterior apron, the border of which is very gently convex and inconspicuously notched in the middle; on each side there is a prominent denticle. Frontal lobes very broadly expanded laterad, semicircular, covering the sides of head from above but exposing the preocular carina which curves mesad above the eye; circular area above antennal socket slightly impressed. Frontal area distinct and impressed. Frontal carinae sigmoidal, fading out before reaching the occipital corner. Front and vertex rather flat, without a median tumulus just behind frontal area and without a deeper transverse furrow in front of the short, toothlike vertical carinae. Eyes convex, with 9-10 facets across the greatest diameter. Supraocular tooth prominent. Occipital corners drawn out in a hornlike fashion. No postocular carinae present. Lower border of cheeks marginate. Antennal scape, when lodged in ventrally immarginate scrobe, surpassing the tip of the occipital spine by a distance exceeding its maximum width. Funicular segments longer than broad; I as long as II and III combined, apical segment (x) as long as VII, VIII and IX combined.

Thorax as shown in Fig. 2. Pronotum without median paired denticles, laterally submarginate, with a faint humeral and stronger posterolateral tubercle; antero-inferior corner rectangular. Mesonotum with an anterior pair of very prominent spines, and a posterior pair of very low denticles. Mesoepinotal constriction moderate. Epinotum unarmed, lacking longitudinal ridges or tubercles on basal face. Epinotal stigma inconspicuous, not situated on a prominent welt. Hind femora (Fig. 3) not conspicuously broadened nor angulate beneath at basal third.

Pedicel as shown in Figs. 2 and 4; both lacking distinct dorsal ridges or tubercles. Petiolar node not noticeably constricted behind. Postpetiole posteriorly faintly bituberculate, shallowly impressed dorsally between tubercles and laterally below each tubercle. Gaster ovoid, tergum I laterally scarcely marginate; sternum I anteriorly truncate, the truncation finely marginate.

Pilosity decumbent to apressed, not scalelike; sparse, scarce and appressed on thorax; more abundant on gaster. Standing hairs confined to tip of gaster.

Female (paratype) - Total length 4.6 mm; head length 1.01 mm; head width 0.91 mm; eye length 0.24 mm; scape length 0.96 mm; thorax length 1.47 mm; hind femur length 1.41 mm; petiole width 0.37 mm; postpetiole width 0.61 mm; fore wing length 3.95 mm; hind wing length 3.07 mm. Light brown, thorax and appendages testaceous. Resembling the worker with the following differences: Eyes larger, with more than 15 facets across the greatest diameter. Ocelli small, lateral ones situated laterally on small tubercles. Lateral pronotal teeth distinct but short and blunt. Mesonotal scutum with a pair of anterior strong teeth, for the rest almost flat; notauli feebly marked. Scutellum with postero-lateral margin of paraptera obliquely upturned; posterior apron bidentate. Basal and declivous face of epinotum subcontinuous, separated in side-view by an indistinct tubercular tooth. Postpetiole much broader, sides somewhat divergent caudad, posterior median and postero-lateral impressions deeper, tubercles stronger. Wings strongly infuscated. Anal vein not curving into cubital vein, but continuing distad after cross vein.

Types - Colombia, Valle Dept.: 3.2 km east of Rio Aguaclara, on the oki Cali Road, in rocky wet quebrada, collected on March 19, 1967 by R. B. Root and W. L. Brown, Jr., 20 workers and 3 females (holotype and paratypes); Mun. Buenaventura, March 16-17, 1967 (Bajo Calima), lowland rainforest, R. B. Boot and W. L. Brown, Jr. col. in rotten wood, 8 workers, 1 female (paratypes). More paratypes of each series were cursorily examined in the Museum of Comparative Zoology Collection at Harvard, to which the holotype will be returned. The remaining specimens are in my private collection (WWK).

Variation - The critical measurements of the worker caste exhibit the ensuing range of variation: Total length 3.4-4.2 mm; head length 0.83-1.01 mm; head width 0.75-0.91 mm; thorax length 1.18-1.39 mm; hind femur length 1.18-1.36 mm. The holotype is darkest, the lightest specimens (present in both series) are entirely yellowish brown; intermediate color phases are also present. The female specimens show a greater degree of variation. The alate specimen described above is distinct by a much bigger gaster (length 1.41 mm against 1.12-1.20 mm in the other specimens), a much broader and dorsally more deeply impressed postpetiole. The other specimens more or less lack the marked separation between basal and declivous face of epinotum and have the lateral pronotal tooth feeble or indistinct. The female from Mun. S. Buenaventura has only very weak anterior paired scutellar tubercles.

Discussion - C. cornutus , named after its hornlike occipital and mesonotal protuberances, belongs to the rimosus-group in the stricter sense on account of the following characters: preocular carina curving mesad above eyes and transecting the antennal scrobe which bears the same sculpture as the rest of the head and lacks a ventral limit behind the eye.

Due to the absence of paired midpronotal teeth, the worker of cornutus runs to kirbyi in my key (Kempf, 1965: 163-5) but differs from the latter species in the hornlike occipital spines, the semi-circular frontal lobes, the spine-like anterior mesonotal teeth, the ecarinate basal face of epinotum.

Other closely related forms, although having well-developed mid-pronotal denticles, longer and anteriorly diverging carinae on vertex, much lower anterior and much stronger posterior mesonotal teeth, a deeper mesoepinotal constriction, carinate borders on epinotum, are vorticis and salvini . Workers of vorticis are distinct from cornutus by having the more expanded and unequally rounded frontal lobes covering the preocular carinae in full-face view; salvini workers, on the other hand, differ in having scalelike hairs, the petiole posteriorly constricted in dorsal view, the hind femora ventrally dilated and angulate at basal third.