Eurhopalothrix clypeata

Known only from the worker holotype.

Identification
It is most similar to Eurhopalothrix pilulifera and Eurhopalothrix alopeciosa, sharing the small size; a similar arrangement and number of erect setae, these almost circular, nearly as broad as wide; and abundant ground pilosity that is strongly flattened and conspicuous. Eurhopalothrix clypeata has an arcuate transverse carina on the clypeus, a character so far unique in the genus. (Longino 2013)

Distribution based on Regional Taxon Lists
Neotropical Region: Guyana.

Castes
Known only from the worker caste.

Nomenclature

 *  clypeata. Eurhopalothrix clypeata Brown & Kempf, 1960: 205, fig. 37 (w.) GUYANA.

Worker
Holotype: TL 2.0, HL 0.52, HW 0.50 (CI 96), scape L 0.32, maximum eye diameter about 0.025, WL 0.52 mm.

This species is a rather typical small member of the holaui group, distinguished above all by its peculiar clypeus, which is divided by an arcuate transverse carina into a large, sloping, concave anterior part and a small, weakly convex, triangular posterior part. As in Eurhopalothrix gravis, Eurhopalothrix alopeciosa and the Old World Eurhopalothrix australis, clypeata is "bald", i.e., the part of the verticocciput occupied by the specialized (in this case very strongly clavate and erect) hairs either lacks the small appressed-squamiform ground pilosity entirely, or else has it very noticeably more sparsely represented than on the frontal section of the head and on the more lateral sections of the occipital lobes. The "bald spot" coincides more or less exactly with the field occupied by the larger specialized hairs, and is frequently more or less accentuated by the presence of whitish foreign material on other parts of the dorsum of the head. In the clypeata holotype, the ground pilosity is much sparser and more restricted in distribution than it is in alopeciosa, gravis, australis or pilulifera. It is absent or extremely reduced, not only in the vicinity of the larger hairs, but also in the middle of the frontal section, on the middle of the clypeus, and on the alitrunk, petiole and gaster. Only on the head, postpetiole, scapes and legs is the ground pilosity reasonably distinct. The virtual absence of the small ground hairs from the gaster is especially striking; this can scarcely be due to abrasion, because all 16 of the larger, erect, thick clavate hairs are present on the first gastric tergite (4 rows of 4 hairs each). Large hairs present in full complement (3 pairs on alitrunk, with one hair missing through abrasion); they all are very thick-clavate, erect, but not quite so extremely inflated and "pompon-like" as in Eurhopalothrix pilulifera or alopeciosa.

The alitrunk is similar to that of Eurhopalothrix speciosa, but in clypeata it is a little shorter and higher and more strongly convex above in profile; the mesonotum is rather prominent, but is not longitudinally carinate; metanotal groove present but shallow. Petiolar node more compressed anteroposteriorly than in speciosa, its anterior face steeply sloping and meeting the summit through a narrowly rounded curve, behind which the convex posterodorsal face slopes away to the rear. Seen from above, the node is very slightly broader than long, with a nearly straight (very feebly concave) anterior margin. Body punctulate-granulose, opaque, the punctures more distinct on gaster. Center of clypeus smooth and shining; mandibles feebly sculptured and weakly shining. Color medium ferruginous, gaster slightly infuscated except at its base.

Type Material
Holotype a unique [NAW] taken by N. A. Weber between the River Cuyuni and the River Mazaruni, British Guiana, presumably in forest, on September 7, 1935.



References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Longino J. T. 2013. A review of the Central American and Caribbean species of the ant genus Eurhopalothrix Brown and Kempf, 1961 (Hymenoptera, Formicidae), with a key to New World species. Zootaxa 3693(2): 101-151.