Cephalotes argentiventris

Known only from a single worker collected by P. J. Darlington in 1938.

Identification
A member of the hamulus clade

Cephalotes argentiventris is an easily distinguished species by its gastral pilosity incomparable with the other known species of the clade. C. argentiventris shares with Cephalotes taino and Cephalotes flavigaster the sinuous body striation and the propodeal dorsum narrower than the mesonotum; with flavigaster the hairs long but not hiding the sculpture. C. argentiventris also shares with Cephalotes hamulus and Cephalotes resinae the thick hairs on the first gastral sternite, but in argentiventris the hairs hide completely the gastral microsculpture.

Distribution based on Regional Taxon Lists
Neotropical Region: Dominican Republic, Greater Antilles.

Nomenclature

 * . Cephalotes argentiventris De Andrade, in De Andrade & Baroni Urbani, 1999: 104, fig. 35 (w.) DOMINICAN REPUBLIC.
 * Type-material: holotype worker.
 * Type-locality: Dominican Republic: Constanza, 3-4000 ft (P.J. Darlington).
 * Type-depository: MCZC.
 * Status as species: Lubertazzi, 2019: 99.
 * Distribution: Dominican Republic.

Description
Diagnosis. A member of the hamulus clade characterised by the following two apomorphies: first gastral tergite completely covered by thick silver-yellowish hairs, and rare hairs on the remaining parts of the body.

Worker
Vertexal angles round, barely crested laterally; vertexal border concave, with a faint margin. Vertex without trace of transversal carina, with a median pair of small denticles. Cheeks marginate posteriorly. Anterior clypeal border concave in the middle and bearing two small lateral teeth. Eyes convex. Mandibles witbout lateral carinae and robust; masticatory margin with an developed apical tooth, a smaller preapical one and an edentate margin.

Mesosoma robust, convex in side view. Scapular angles bearing a small denticle. Anterior pronotal border marked by an impressed carina. Humeral angles with a pair of stout, obtuse spines and pointed anteriorly. Pronotal sides straigbt, ending in a small, round tooth visible in dorsal view. Promesonotal suture impressed. Mesonotal teeth broadly rounded. Propodeal suture deeply impressed dorsally. Propodeum ca. 1/4 narrower than the mesonotum, with differentiate basal and declivous faces. Basal face ca. 1/3 broader than long, with slightly convex sides anteriorly, straightening posteriorly and without denticles; declivous face as long as the basal face, its sides slightly converging posteriorly. Propodeal spines slightly shorter than the basal face of the propodeum, thick and diverging.

Petiole ca. 1/2 broader than long, its anterior face truncated and marginate dorsally by a crenulate carina interrupted in the middle; its sides converging posteriorly and bearing a pointed tooth medially. Postpetiole ca. 1/4 broader than and as long as the petiole; postpetiolar spines pointed, inserted anteriorly and curved backwards.

Gaster with a narrow lamellaceous anterior border, reaching the first gastral stigma at maximum.

Legs. Fore coxae without a broad lobe or angle anteriorly. Hind femora slightly inflated in the middle; mid and hind basitarsi laterally compressed in dorsal view; their sides narrowing distally in side view.

Sculpture. Head minutely reticulate; vertexal area covered by broad, irregular foveae gradually shallower towards the eyes. Frontal carinae reticulate and superficially rugulose on their sides. Ventral side of the head laterally covered by thick, sinuous striae. Hypostomal area deeply reticulate. Cheeks reticulate and superficially rugulose.

Mesosoma, petiole and postpetiole superficially covered by reticulation and longitudinal sinuous striae. Declivous face of the propodeum with thin, longitudinal striae and reticulate. First gastral tergite covered by faint punctures. Corresponding sternite with superficial longitudinal rugosities on the anterior half of its sides, the rest with impressed reticulation and slightly shining posteriorly.

Coxae reticulate and transversally rugulose on the outer face. Femora deeply reticulate and with superficial, thin, irregular rugae on the distal part. Outer face of tibiae and basitarsi with longitudinal, anastomosing rugosities, the other faces reticulate.

Pilosity. Body with the following types of hairs: (1) truncate, erect to suberect, sparse and long on most of the body; (2) thin, sparse, appressed and short on the head, on the mesosoma and pedicel; (3) thick, dense and appressed on the gaster, sparser on the extensor face of the femora; (4) thin, pointed, erect, sparse and long on the gastral sternites.

Colour. Black. Frontal carinae, scape, first funicular joint, masticatory margin of the mandibles, tips of the pronotal, propodeal, and pedicellar spines and tarsomeres dark orange to light brown; remaining funicular joints brown. Gaster black with a silverish aspect due to the pilosity.

Measurements (in mm) and indices: TL 6.28; HL 1.56; HW 1.72; EL 0.48; PW 1.64; PeW 0.68; PpW 0.87; HBaL 0.64; HBaW 0.18; CI 110.2; PI 104.8; PPeI 241.1; PPpI 188.5; HBaI 28.1.

Type Material
Material examined. - holotype worker (unique) without fore left tibia and tarsus, from Constanza, 3-4,000 ft, Dominican Republic, P. J. Darlington.

Etymology
Derivatio nominis: From the Latin argentum (= silver) and venter (= abdomen), referred to the distinctive coloration of this species.

References based on Global Ant Biodiversity Informatics

 * Perez-Gelabert D. E. 2008. Arthropods of Hispaniola (Dominican Republic and Haiti): A checklist and bibliography. Zootaxa 1831:1-530.
 * de Andrade, M.L. & C. Baroni Urbani. 1999. Diversity and Adaptation in the ant genus Cephalotes, past and present. Stuttgarter Beitrage zur Naturkunde Serie B 271. 893 pages, Stuttgart