Centris (Heterocentris) ceratops, Vélez, Danny & Vivallo, Felipe, 2012

Vélez, Danny & Vivallo, Felipe, 2012, A new South American species of Centris (Heterocentris) Cockerell, 1899 with a key to the species with horn-like projections on the clypeus (Hymenoptera: Apidae: Centridini), Zootaxa 3357, pp. 49-55 : 50-54

Centris (Heterocentris) ceratops new species

( Figures 1–4 )

Diagnosis. Clypeus with a horn-like projection compressed dorsoventrally and with acute apex. This projection originates in the upper margin of the clypeus near the epistomal suture and extends divergently downward relative to the clypeal disc reaching the base of the labrum. Posterior surface of the gena next to the hypostomal suture with a rounded laminar projection.

Description. Holotype female. Measurements: Approximate body length: 11.3; head width: 3.9; forewing length: 7.5; F1 length: 0.9; F2 length: 0.3; F3 length: 0.4; mandible length: 2.0; mandible basal width: 0.8; thorax width: 4.5. Coloration: Head and mesosoma dark brown to black, with mandible (except apex black), clypeus (except the horn) and the labrum yellow (except the disc translucent and the distal margin dark brown); horn blackish with its basal internal surface yellow. Malar area and antenna dark brown, slightly lighter on scape. Tegula yellowish brown, slightly translucent. Legs light brown, darker on the first pair. Metasoma orange brown, with the distal margin of terga and sterna (except T6 and S6) yellow and slightly translucent. Integument and sculpture surface: Outer surface of mandible shiny and foveolate, except the apical tooth opaque and finely rugose. Clypeus shiny, finely rugulose with its latero-distal edges foveolate; with coarse and sparse punctation on the lower half, below the horn. Dorsal surface of the horn with broad and sparse punctation. Labrum shiny, finely aciculate in the translucent areas and with sparse punctation throughout its surface. T1 alutaceous, with dense punctation on the disc, more dispersed laterally. T2-T4 alutaceous and with similar punctation, but more dispersed and finer than in T1. T5 with similar punctation than on T4, but less dense. T6 with fine and dense punctation. Pubescence: Predominantly yellow, except gena and mesepisternum whitish, and vertex with brown and yellow hairs intermixed. Labrum with yellow hairs at the edges of the anterior half, and whitish, plumose, long and dense hairs at the distal margin. Mandible with brown and yellow, long and simple hairs in the outer and inner edge, being whitish, short and plumose near the acetabulum. Fore and middle femora and tibiae with white yellowish pilosity, being yellowish on the tarsi. Hind legs with yellow pilosity, except the inner surface of basitarsi with brown hairs. T1 with yellowish, long and plumose pilosity at sides, with simple and shorter hairs on disc. T2 and T3 with dark brown, short and simple hairs on discs, with long brown yellowish hairs on the sides. T4 with hairs of the same coloration, short and simple in the anterior half of the disc, with yellow, longer and simple hairs at sides and on the distal half of the tergum. T5 with yellow hairs, simple and equal to or longer than in T4 being more dense than in the previous tergum. Prepygidial and pygidial fimbriae with orange, thick, long and simple hairs, being shorter near the pygidial plate. Structures: Flabellum almost circular slightly projected forward. Mandibles 2.5 times longer than wide, strongly curved apically and with three pointed teeth, the third longer than the second. Acetabular carina reaching the base of the third tooth. Clypeus convex with a horn compressed dorso-ventrally originated in the upper margin of the clypeus near the epistomal suture; the projection extends divergently downward relative to the clypeal disc reaching the base of the labrum. Labrum strongly concave and semi-triangular with distal margin straight and thick, 1.1 times longer than wide. Shortest distance between the clypeus and the eye smaller than the basal width of F1. Vertex above the ocular orbits. Scutellum convex in lateral view. Eyes slightly divergent downward with a gentle curve in the upper half. Fore and hind elaiospathes well-developed, both with continuous combs. Primary basitibial plate elliptical with rounded apex, secondary plate vestigial, almost absent and covered by short and dense pilosity. Primary pygidial plate with rounded apex, secondary plate with the distal margin truncated, as usual in the females of Centris (Heterocentris) .

Type material. Holotype female with the following label: “ COL. Sucre. Coloso. Ser. Alto 29-01-10 Col: Morelo & Vargas”. The holotype is in good condition, but with the flagellum of the left antenna lacking. The type specimen is deposited at the Laboratorio de Investigaciones en Abejas Silvestres of the Universidad Nacional de Colombia ( LABUN), Bogotá, Colombia with the catalogue number LABUN 21948.

Type locality. Colombia: Department of Sucre: Colosó (probably “Quebrada Sereno Alto”, 9°33’32.9854”N, 75°20’16.1051”W).

Etymology. From Greek, keratops, in reference to the clypeal horn.

Discussion. Centris ceratops new species belongs to a small group of species in which females have one or two horns on the clypeus. The function of these projections is not clear, but they are probably not related to nesting activities since the only horned species for which the nesting biology is known, Centris bicornuta , does not construct its nests; in fact, it relies on cavities made by other insects to construct their cells ( Vinson et al., 2011b) as probably occurs in other species of the subgenus. It is possible that the function of this structure can be the same as observed in Osmia cornuta (Latreille) ( Apidae sensu lato: Megachilinae ), in which females use the horn to fight natural enemies, mainly cleptoparasitic flies and other bees while they are in their nests (Monzón, personal communication). Another function could be to facilitate the breaking of the cell during the emergence, but this has not been observed in Centris and males would need it too. The holotype shows no signs of attrition in the horn nor on the mandibles, despite of being a relative old specimen as inferred from wing wear.

Despite the disadvantages and doubts that may arise concerning the validity of describing a new species based solely on a single specimen, without determining the intraspecific variation that allow an objective identification between morphologically similar species, Centris ceratops new species is a completely different species from those previously described in C. (Heterocentris). Intraspecific morphological variation observed in the majority of species of Centridini is almost exclusively related to size and coloration of the integument and the pubescence, with some extreme cases, such as observed in C. (Wagenknechtia) muralis Burmeister , C. (Paracentris) caesalpiniae Cockerell , Centris (Centris) flavifrons (Fabricius) , and C. (Centris) varia (Erichson) , which have beta-males or metanders, and even dichromatric males and females in case of the latter species. In general, the females of Centridini have little intraspecific variation and high interspecific differentiation, especially in structural characters. This morphological stability is not always observed in males, which may have a greater degree of external morphological variation ( Thiele, 2003), and even in the genitalia ( De la Hoz, 1970), making the genital capsule and its associated sterna of little utility to identify species, but a good source of phylogenetic characters for recognizing major internal lineages within the tribe (Vivallo & Melo, in preparation).

*The references cited here are those published before the Catalogue of Bees in the Neotropical Region ( Moure et al., 2007),

except some published after but with doubtful identifications or cited using synonymies.

1 Cited as C. analis , C. totonaca Cresson and C. minuta Mocsáry.

2 Cited as C. totonaca .

3 Cited as C. analis and C. minuta .

4 Cited as C. difformis .

5 Uncertain identity.

6 Uncertain identity, probably C. terminata .

Before describing Centris ceratops new species search for additional material were made in major Colombian entomological collections (Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogotá; Laboratorio de Investigaciones en Abejas Silvestres, Universidad Nacional de Colombia, Bogotá; Museo de Entomología “Francisco Luis Gallego”, Universidad Nacional de Colombia, Medellin; Instituto Alexander von Humboldt, Villa de Leiva) and some international institutions (e.g, Coleção Entomológica Padre Jesús Santiago Moure of the Universidade Federal do Paraná, Brazil, the Hymenoptera collection of the Natural History Museum, London, England). Despite the effort no additional specimens were located and possibly only new collections in northwest Colombia could provide new specimens of C. ceratops new species, including of male specimens.

Finally, we emphasize that the diagnostic characters of C. ceratops new species are all structural, evident and easily observed, facilitating its identification, making it unmistakable among other species of the genus.

Figures

FIGURES 1 – 4. Centris ceratops new species (holotype female). 1, Head frontal view. 2, Head lateral view. 3, Head, posterior view showing the laminar projection of the gena. 4. Lateral view. Scale bar: 1 (mm), except figure 3: 0.5 (mm).