Camponotus socorroensis

Identification
At first sight this ant might be regarded as a small and depauperate form of Camponotus mina, but it evidently represents a distinct species. The major worker can be readily distinguished from that of mina by the shorter antennal scapes, ecarinate clypeus, much more diverging frontal carinae, anteriorly narrowed pronotum, finer sculpture, etc. Wheeler (1934) -

Distribution based on Regional Taxon Lists
Neotropical Region: Mexico.

Nomenclature

 * . Camponotus (Myrmobrachys) socorroensis Wheeler, W.M. 1934f: 142 (s.w.m.) MEXICO (Revillagigedo Is).
 * Status as species: Wheeler, W.M. 1935g: 44; Kempf, 1972a: 54; Bolton, 1995b: 124.

Worker
minor Length 3.3-3.5 mm.

Very similar to the worker major, but the head much smaller and narrower, with slightly convex posterior border, more convex and more posteriorly situated eyes. Mandibles much narrower and less convex. Clypeus broader, but ecarinate as in the major. Antennal scapes nearly straight, extending half their length beyond the posterior corners of the head. Thorax like that of the major but even lower and less arcuate; pronotum semicircular, not narrowed anteriorly, distinctly marginate at the sides; base .of epinotum decidedly longer than the declivity. Petiole similar to that of the major, gaster proportionally shorter.

Sculpture, pilosity and color as in the major, but the clypeus and posterior portions of the cheeks darker and more brownish, as are also the bases of the femora and the antennal funiculi beyond the first joint. Foveolae on the clypeus and cheeks fewer and less conspicuous.

major Length 5-5.2 mm.

Closely related to Camponotus brevis and Camponotus mina. Head moderately large, subtrapezoidal, slightly longer than broad, the posterior border nearly straight, the sides feebly rounded behind, more convex in the region of the cheeks. Mandibles stout, very convex, 6-toothed. Clypeus sub rectangular, slightly longer than broad, evenly convex but not carinate in the middle. Frontal area distinct, very small, transversely trapezoidal; frontal carinae closely approximated in front, strongly sinuate and widely divergent posteriorly; frontal groove distinct. Eyes rather large and convex, as long as their distance from the posterior border of the head. Antennae slender; scapes curved, extending only a distance equal to their greatest diameter beyond the posterior corners of the head. Thorax short, shaped much as in brevis but decidedly lower and less strongly arcuate above in profile; pronotum depressed, distinctly narrowed anteriorly and nearly as long as broad, the humeri broadly rounded, submarginate. Mesonotum trapezoidal, somewhat broader than long; epinotum small and narrow, in profile with subequal base, and declivity, the former straight and sloping, forming a distinct obtuse angle with the more abrupt, slightly concave declivity petiolar scale thick, twice as high as long, nearly as thick above as below, with flat posterior surface, the anterior surface flat below, very convex above; seen from behind the superior border is broadly rounded, the sides straight and converging ventrally. Gaster elongate-elliptical. Legs rather short.

Mandibles, gula, posterior corners of head, coxae and legs distinctly shining; dorsal surface of head and thorax subopaque; petiole and gaster lustrous. Mandibles finely and superficially shagreened and sparsely punctate; head and thorax finely and densely punctulate, the clypeus and cheeks also with sparse, piligerous foveolae, which on the occiput and pronotum are replaced by sparse, coarse punctures. Gaster finely and transversely shagreened or striolate with numerous transverse, piligerous punctures. Legs more finely shagreened than the gaster, sparsely punctate.

Hairs glistening white, erect, rather coarse, abundant and moderately long on the dorsal surface of the head, thorax, petiole and gaster; longest on the epinotum, absent on the pleurae; on the clypeus and cheeks short, stiff and obtuse, on the legs short and obtuse, much more numerous on the tibiae than on the femora. Antennae with dilute, appressed pubescence, tips of scapes with a few short hairs.

Black; mandibles, antennae and anterior third of head, including the mandibles, red; gula and fore coxae castaneous; legs more yellowish or testaceous, terminal funicular joints and the last joint of each tarsus fuscous; mandibular teeth black.

Male
Length 3.5-4 mm.

Very similar to the male of brevis in structure, sculpture, pilosity and color but slightly smaller and with somewhat longer antennal scapes, more strongly carinate clypeus, much narrower mesonotum and longer and more convex epinotum.

Type Material
Described from five major workers, ten minor workers and twelve males taken at Grayson Cove, Socorro Island (V.4.'25).

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
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Vásquez-Bolaños M. 2011. Lista de especies de hormigas (Hymenoptera: Formicidae) para México. Dugesiana 18: 95-133