Cyphomyrmex peltatus, Kempf, W. W., 1966

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 : 181-184

8. Cyphomyrmex peltatus n. sp.

(Figs. 13, 20, 35, 50)

Worker (holotype). - Total length 3.1 mm; head length 0.72 mm; head width 0.69 mm; thorax length 1.04 mm; hind femur length 0.85 mm. Ferruginous; dorsum of head, scapes and tibiae strongly, promesonotum and gaster more lightly intuscated. Integument densely and finely granulate-punctate.

Head as shown in Fig. 13. Mandibles finely striolatepunctate, somewhat shining. Anterior border of clypeus very gently convex, almost straight; lateral teeth triangular, not projecting. Frontal area impressed. Frontal lobes semicircular. Frontal carinae almost straight, diverging caudad, attaining tip of occipital corner. The latter scarcely, salient. Front with a weak and low tumulus just behind frontal area, followed by a shallow transverse depression between greatest constriction of frontal carinae. Carinae of vertex strong, subsemicircular, diverging both cephalad and caudad, the posterior end does not attain the occipital corner. Occiput perpendicular to vertex, distinctly excavate. Preocular carina curving mesad above eye; postocular carina extending from occipital corner to the inferior border of eye, containing the supraocular tooth, which in full-face view appears just as a blunt angle of postero-lateral border of head. Eyes with 7 facets across greatest diameter. Inferior border of cheeks sharply marginate. Antennal scape gradually but strongly incrassate toward apex; surpassing in repose the occipital corner by a distance which distinctly exceeds its maximum width. Funicular segments II-IX not longer than broad, segment I as long as II and III combined.

Thorax as shown in Fig. 20. Midpronotal tubercles absent. Lateral pronotal tooth tubercular and obtuse, sending foreward a weak carinule which separates the pronotal dorsum from its sides; anteroinferior corner rectangular. Humeral angle not expressed. Mesonotum with a shallow pentagonal impression margined by blunt carinae formed by the very low and weltlike anterior and posterior pair of tubercles; the latter form at the antero-lateral corner a bluntly projecting tumulus. Mesoepinotal constriction rather strong. Basal face of epinotum laterally immarginate with two indistinct tubercles antero-laterally, blending posteriorly into the declivous face, which is laterally immarginate. Oblique welt on sides of epinotum indistinct. Hind femora (Fig. 50) ventrally angulate at basal third, postero-ventral border narrowly crested.

Pedicel as shown in Figs. 20 and 35. Petiolar node nearly twice as broad as long, the anterior corners rounded, posteriorly strongly constricted in front of postpetiolar insertion; no dorsal ridges nor posterior salient laminule present. Postpetiole without a distinct anterior face, its dorsal face with a sagittal impression and postero-lateral impressions flanking a pair of blunt and low tubercles, which do not project beyond the entire posterior border. Tergum I of gaster with a feeble antero-median groove; lateral marginations at best vestigial.

Hairs minute, short, shiny and recurved, not scale-like, never completely appressed.

Female (paratypes). - Total length 3.6-3.7 mm; head length 0.77-0.80 mm; head width 0.75-0.77 mm; thorax length 1.15-1.20 mm; hind femur length 0.88-0.91 mm. Resembling the worker, with the differences peculiar to the caste. - Ocelli very small. Eyes with about 12 facets across the greatest diameter. Lateral pronotal tooth low, blunt, tumuliform. Mesonotum: Scutum with an antero-median, laterally marginate elevation between the anterior arms of the shallowly impressed Mayrian furrows; notauli indistinct. Paraptera flat with rounded border. Scutellum posteriorly bidentate, with a semicircular excision between the teeth. Epinotum continuously declivous, without a differentiated basal face; its upper portion laterally sharply carinate. Middorsal impression of postpetiole deeper. Wings unknown.

Male unknown.

Specimens examined: 28 workers and 3 females, as follows: Brazil, Santa Catarina; Ibicare, September 1960, F. Plaumann leg. 6 workers, 1 female (holotype and paratypes); Chapeco, V-1957, F. Plaumann leg. 1 worker; Nova Teutonia, strays from 8 different collections made between October 1953 and February 1963 by F. Plaumann, 17 workers; Rio Grande do Sul: Barao de Cotegipe, July 1960, F. Plaumann leg. 2 workers, 2 females; Boqueirao, September 1960, F. Plaumann leg. 2 workers. (All paratypes and deposited in WWK).

Discussion. - The holotype worker is the tallest of the series; the smallest worker examined measures as follows: total length 2.8 mm; head length 0.66 mm; head width 0.63 mm; thorax length 0.93 mm; hind femur length 0.75 mm. Otherwise the paratypes agree completely with the holotype in all essential features and details.

The present species is very close to rimosus but a few constant characters help to differentate both forms. The worker of peltatus differs from sympatric morphs of rimosus in the following characters: Lack of midpronotal tubercles; pentagonal impression on mesonotum, margined by the 4 low welts, the anterior pair forming a tubercle at the anterolateral corner of the pentagon; epinotum completely unarmed, the anterior pair of tubercles bluntly rounded and only vestigial; middorsal postpetiolar impression always deeper; hairs as a rule thin, recurved, not scale-like. The female is at once recognized by the lack of epinotal spines.

The typical peltatus is known from southeastern Brazil in the States of Santa Catarina and Rio Grande do Sul. 1 provisionally associate with the same species stray specimens from northern Brazil (Amazonas: Benjamim Constant, Manaus; Para: Belem; Mato Grosso: Utiariti) and Surinam (La Poulle, Vank; erroneously identified as kirbyi in my paper of 1961: 518), although they are smaller in size, of lighter color, having shorter scapes and rather scale-like hairs.

Another species from Mexico, dentatus Forel , is doubtless a close relative of peltatus ; it will be differentiated in the ensuing description.