Cyphomyrmex nesiotus, Snelling, R. R. & Longino, J. T., 1992

Snelling, R. R. & Longino, J. T., 1992, Revisionary notes on the fungus-growing ants of the genus Cyphomyrmex, rimosus-group (Hymenoptera: Formicidae: Attini)., Insects of Panama and Mesoamerica: selected studies., Oxford: Oxford University Press, pp. 479-494 : 485-487

Cyphomyrmex nesiotus , new species

(Figs 30.7, 30.15, 30.27, 30.28)

Diagnosis. A member ofthe kirbyi subgroup related to C. kirbyi Mayr . Workers and femal es differ from these castes of C. kirbyi by the presence of conspicuous parafrontal tubercles on the clypeus, the sinuate apical clypeal margin and the very different profile of the mesosomal dorsum (compare Figs 30.12, 30.15

Males are unknown for most species of the kirbyi complex including C. kirbyi , and it is not presently possible to arrive at a meaningful suite of diagnostic features (see the Discussion).

Description

Worker holotype. Measurements: Total length 3.3 (2.9-3.4); head length 0.82 0.74-0.86; head width 0.72 (0.68-0.73,; mesosomal length 1.13 -(1.00-1.14); metafemur length 1.01 (0.91-1.03) mm.

Ferruginous, front of head and mesosomal tubercles darker, dorsum of gaster very weakly darker; mandibles brighter reddish. Integument opaque throughout, minutely granulose.

Head shape as in Fig. 30.7. Mandible very finely longitudinally striolate; basal tooth much smaller than others. Anterior margin of clypeus with shallow median emargination; parafrontal tooth distinct. Frontal area impressed. Margin of frontal lobe rounded, corner above parafrontal tooth broadly rounded; posterior portion of frontal carina sigmoidal and attaining occipital corner. Submedian carinae of vertex short, obtuse, subparallel. Postocular carina absent. Supraocular tubercle very weak. Occipital corner little projecting, not dentate. Occipital margin, in frontal view, broadly concave, more strongly emarginate in middle. Posterior genal margin subcarinate to base of mandible. Scape, in repose, extending beyond occipital corner by about its own greatest thickness; funicular segments 2-8 distinctly longer than broad. Eye with about nine facets along greatest diameter; eye length equal to, or slightly greater than, oculomandibular distance.

Mesosoma as in Fig. 30.15. Submedian pronotal tubercles absent; lateral tubercle low and obtuse; humeral ridge anterior to lateral tubercle, present but weak to obsolete; antero-lateral corner of pronotum nearly right-angular. Disc of mesonotum slightly depressed; anterior tubercle obtuse-conical; weak ridge present between anterior tubercle and indistinct posterior tubercle. Mesometanotal impression deep. Dorsal ridges of propodeum very weak. Metafemur (Fig. 30.27) neither dilated nor ventrally ridged in basal one-third.

Node of petiole depressed and only a little broader than long. Posteromedian depression of post-petiole shallow and poorly defined.

Pilosity flattened, scale-like, and appressed on most surfaces, more slender on scape and femora; hairs more erect, but curled, on gena and distally on gaster; gaster with suberect to erect, long, simple hairs distally and on ventral segments.

Female. Measurements: Total length 3.83-4.00; head length 0.88-0.90; head width 0.78-0.81; mesosoma length 1.2 3- 1.28; metafemur length 1.03-1.06; forewing length 3.33 mm.

Head as in worker except that minute ocelli are present; eye with about 13-15 facets along greatest diameter.

Lateral pronotal tooth low, blunt. Mesonotum anteriorly with weak swelling between mid-line and Mayrian furrows; disc slightly depressed; notauli indistinct. Axilla flat, margin rounded. Posterior margin of scutellum bidentate, emargination semicircular, Propodeum, in profile, evenly sloping, without differentiated basal face; lateral carina obsolete. Dorsal depression of post-petiole distinct.

Male. Measurements: Total length 3.67; head length 0.74; head width 0.6 3; mesosoma length 1.27; wing length 3.2 3 mm.

Head and body dark brown, appendages reddish brown, mandible, apical funicular segments, and distitarsi paler. Wings dark brownish.

Head as in Fig. 30.28. Mandible with four distinct triangular teeth and minute inner tooth; diastema between second and third teeth much shorter than that between third and fourth. Apical margin of clypeus abruptly depressed below disc, with small median emargination. Frontal lobe strongly raised, outer margin weakly convex, lower end angulate in frontal view; frontal carina absent above frontal lobe. Occipital corner obtuse, not projecting; occipital margin concave in frontal view. Posterior margin of gena carinate to base of mandible. Scape extending beyond occipital corner by more than three times its greatest thickness; funicular segments 2-5 about twice longer than wide. Eye large, eye length about twice longer than oculomandibular length. Head granulopunctate and with fine, irregular rugules, becoming reticulate on vertex.

Lateral pronotal tubercle small, acute, with distinct carina extending forward from tubercle to transverse post-marginal ridge; propleuron with a few longitudinal rugulae. Mayrian furrows of mesonotum broad and deep; parapsidal lines weak. Scutellum depressed below level of mesonotum, apico-lateral teeth distinct, margin between them shallowly concave. Propodeum in profile without distinct basal face, subiateral carinae distinct to apex. Integument dull, reticulo-punctate and with irregular rugulae, coarser on dorsal surface.

Petiole with antero-ventral process; node depressed. Postpetiole with weak depression along length of node. Petiole and post-petiole dull, reticulo-punctate.

Gaster slightly shiny, shagreened and with sparse fine punctures on first tergum.

Pilosity of head and body sparse, depressed and not at all scale-like; a few longer, suberect hairs on apex and venter of gaster.

Type material

Holotype worker: Isla Isabella, Santo Tomas V. Sierra Negra, elev. 1050 ft., Galapagos, ecuador, 9 June 1982 (YD. I.ubin, No. 147), in Natural History Museum of Los Angeles County. Paratypes: six workers, three females, one male, same data as holotype; two workers and two females, Los Tintos, 1100 feet elev. Sierra Negra, Isla Isabella, 10 June 1982 (Y. D. Rubin, No. 156). Paratypes in LACM, MCZ, USNM.

Etymology. Latinization of the Greek nesiotes (insular).

Discussion. In Kempf' s key to species of the C. rimosus group, C. nesiotus will go to C. kirbyi Mayr . Mayr's worker tvpes were from an unknown locality in Colombia. Santschi 1921) recorded specimens from Guayaquil, Ecuador, as C. kirbyi . The Guayaquil specimens are in the collection of the Paris Museum; they are incorrectly identified and belong to an apparently undescribed species.

The worker of C. kirbyi was redescribed, from type material, bv Kempf 1966'. The following differences have been noted between C. kirbyi , as redescribed by Kempf, and C. nesiotus : in C. kirbyi the clypeal apex is without a median emargination; the parafrontal tooth is obsolete; the antennal scape extends beyond the occipital corner by nearly twice its maximum thickness; the mesosomal profile is different (Fig. 30.12); the petiole does not possess an antero-ventral process. These differences, except that of mesosomal profile, also exist between females of the two species.

Male specimens are more difficult to deal with, since this caste is unknown for many members of the C. rimosus group. We have seen only males of C. minutus Mayr , C. wheeleri Forel , and C. rimosus (Spinola) . The male of C. wheeleri has slender propodeal spines and is easily separated from that of C. nesiotus . In addition, the apical margin of the clypeus is evenly convex in frontal view and is not abruptly depressed below the level of the disc, and frontal carina is present to the occipital corner.

In males of C. minutus , the apical portion of the clypeus is somewhat depressed, but not abruptly so as in C. nesiotus , and the margin is transverse. The frontal carina is present above the frontal lobe in C. minutus , but ends at about the level of the anterior ocellus. The occipital corners are prominent and dentiform in C. minutus and, in this species, the propodeum is dentate and there is no antero-ventral process on the petiole.