Ruizantheda centralis, Gonzalez-Vaquero, Rocio Ana & Roig-Alsina, Arturo, 2009

Gonzalez-Vaquero, Rocio Ana & Roig-Alsina, Arturo, 2009, The bee genus Ruizantheda (Hymenoptera: Halictidae), its scope and description of a new species, Zootaxa 2282, pp. 62-68 : 65-67

Ruizantheda centralis n. sp.

( Figs. 1–7 )

Diagnosis. This species is closely allied to R. proxima , from which it is distinguished by its smaller size, the stronger sculpture of the integument, the shorter vestiture, the mandible of the male, not expanded basally, and the glabrous ventral side of the male mesothorax. It is distinguished from R. divaricata by its weaker sculpture of the integument, the modified venter of the male mesothorax, and the stronger basal projection of the retrorse lobe of the male genitalia. It is distinguished from both species by the bare eyes, and the truncate pygidial plate of the male.

Description. Male (holotype). Length, 7.1 mm; forewing length, 5.7 mm (paratype, length, 7.0 mm; forewing length, 5.5 mm).

Color: Head and mesosoma black with a metallic bluish tint, more evident on head and on dorsal and lateral parts of thorax, scutellum with a purplish tint; hypostomal area dark reddish brown. Following parts yellow: clypeus, labrum, mandible except reddish apex, small spot on hypostomal area close to mandible, anterior surface of scape and pedicel, small spot on translucent tegula, anterior leg beyond coxa, small spot on ventral surface of mid coxa as well as rest of mid leg, except basal brown stripe on upper two thirds of mid tibia, ventral surface of hind coxa, and rest of hind leg, except basal and median brown spots on upper surface of tibia. Disc of second to sixth sterna of paratypes yellowish and S1 with small lateral and apical yellowish spots, brownish in holotype probably due to preservation of specimen. Following parts brownish: rest of antenna, two small spots on clypeus, pronotal lobe, and metasomal terga with translucent apices. Wings light amber with brown veins and pterostigma.

Pubescence: Whitish. Head with dense, appressed, short, plumose hairs on lower part of paraocular area and gena; those hairs on paraocular area interspersed with longer hairs as long as 1.7 times MOD; erect hairs on genal area as long as 1.1 times MOD; hairs on vertex as long as 1.3 times MOD. Clypeus and scape with sparse erect hairs, 0.6–1 times MOD. Thorax with dense, short, simple hairs on scutum, scutellum, and metanotum, as long as 0.3 times MOD; those on pleura short, plumose, as long as MOD; scutellum with sparse, plumose hairs, 0.7 times MOD; metanotum and lateral side of propodeum with denser, plumose hairs, 1.1–1.3 times MOD on metanotum, 0.4–0.8 times MOD on lateral side of propodeum. Lateral part of pronotal collar and base of metanotum with dense areas of appressed, very short hairs. Vestiture sparse on legs. Metasoma with basilateral bands of short appressed hairs on T2–T3; terga without apical bands; disc of terga with very short erect hairs, as long as 0.2 times MOD; T2–T7 with some longer hairs on lateral apical part, with their apices directed latero-posteriorly. S1–S5 glabrous, S6 with sparse hairs laterally and apically.

Sculpture: Labrum impunctate. Clypeus with punctures denser at sides, separated by 0.5 puncture diameter; punctures sparser apically and medially, leaving median longitudinal smooth upper band. Face with punctation finer and denser than on clypeus, on supraclypeal area separated by 0.3–0.5 their diameter. Punctures deep, dense on scutum and metanotum, separated by half puncture diameter. Disc of scutellum with impunctate areas as large as 2–3 puncture diameter; remainder of scutellum with punctures similar to those on scutum. Mesepisternum with strong, coalescent punctures; metapleuron punctate-striate. Metapostnotum with strong punctures, rugose-reticulate, posterior margin smooth. Propodeum with punctures separated by 1–1.5 times their diameter. Metasoma with fine, dense punctuation. Surface between punctures smooth.

Structure: Head broader than long, 1.15:1 (paratype, 1.13:1). Proportion of lower to upper interocular distance 0.68:1. Labrum broader than long, 2.3:1, truncate, bearing a row of approximately 30 flattened setae ( Fig. 1 ). Clypeus broader than long, 1.52:1 (paratype, 1.54:1). Proportion of interantennal to antennocular distance, 1.6:1 (paratype, 1.7:1). Proportion of posterior interocelar to ocelo-ocular distance, 1.9:1 (paratype, 2:1). Proportion of length of scape, pedicel and first three flagellomeres 1.64:0.50:0.57:1.14:1. Second flagellomere 1.77 times as long as its apical width ( Fig. 2 ). Venter of mesothorax longitudinally concave, with anterior and posterior tubercle at each side. Pygidial plate with strong marginal carina, truncate ( Fig. 3 ). S1 convex. Apical margin of S4 medially projected, bearing row of six flattened, juxtaposed setae, with their apices bent down ( Figs. 4–5 ). S7–S8 as in figure 7. Genital capsule with basal projection on retrorse lobe of gonocoxite ( Fig. 6 ).

Female. Length, 7.2 mm; forewing length, 5.8 mm.

Color: Head and mesosoma as in male, but following parts brownish: clypeus, labrum, mandible, hypostomal area of head, antenna, tegula, legs and metasoma. Wings as in male.

Pubescence: Whitish. Head with erect, plumose hairs; those on paraocular area and vertex as long as 1.3– 1.5 times MOD; hairs on lower part of genal area twice MOD; upper part of genal area with appressed, plumose hairs, as long as 0.5–1.2 times MOD. Thorax with dense, short, simple hairs on scutum, scutellum, and metanotum similar to those of male, but longer on pleura (1.5–1.8 times MOD), sides of scutum (up to 1.6 times MOD), metanotum and lateral side of propodeum (1.4–1.7 times MOD). Lateral part of pronotal collar and base of metanotum with dense areas of appressed, very short hairs, as in male. Vestiture dense on legs. Metasoma with basilateral bands of short appressed hairs on T2–T3; terga without apical bands; disc of terga with sparse, very short erect hairs; anterior part of T1 with erect, plumose hairs, as long as 0.75 times MOD, directed latero-anteriorly; T4–T5 laterally with some longer hairs, with their apices directed latero-posteriorly. S2–S5 with long, short-barbed hairs, with their apices curved, directed posteriorly.

Sculpture: Labrum with verrucose, median, basal elevation. Clypeus with punctures separated by 0.5–0.7 puncture diameter; rest of face with punctation finer and denser than on clypeus. Punctures on scutum, scutellum, metanotum and pleura similar to those of male. Dorsal surface of metapostnotum rugose-striate, with posterior margin microareolate. Metasoma with fine, dense punctuation. Surface between punctures smooth, but microreticulate on metasoma.

Structure: Head broader than long, 1.2:1. Proportion of lower to upper interocular distance 0.75:1. Labrum broader than long, 1.8:1. Clypeus broader than long, 1.87:1. Proportion of interantennal to antennocular distance, 0.6:1. Proportion of posterior interocelar to ocelo-ocular distance, 1.9:1. Proportion of length of scape, pedicel and first three flagellomeres 7.33:1:1:0.83:1. Inner hind tibial spur pectinate, with three teeth. Pygidial plate rounded, with strong margin. S1 convex.

Distribution. Argentina: provinces of Chaco, Santiago del Estero, and Santa Fe.

Specimens examined. ARGENTINA, HOLOTYPE male: Santiago del Estero, number 23.120, XI/1927, M. Gómez (MACN); PARATYPE: 1 male, Santa Fe, Rosario, 12/I/1911, Moya spinosa , “133”; OTHER SPECIMENS: 1 male, Santiago del Estero, number 23.234, Dep. Matará, Desvío 511, XI/1928, M. Gómez; Santa Fe, number 11.942, cerca de Rosario, J. Lazarte; 1 female, Chaco, number 6.879, 30/VIII/1904, Lynch Arriabalzaga. All specimens in MACN.

Etymology. This species is named for the distribution of the species, between the known geographical records of R. divaricata and R. proxima .

Comments. Two males are not designated as paratypes, because they are in poor condition, although there is no doubt that they belong to the species. The studied female agrees with the males in sculpture of the integument, color and vestiture, but since it comes from a far locality where the males were collected, it is tentatively associated. One male was collected on Moya spinosa Grisebach (Celastraceae) , a small tree that grows along the Paraná River.

Figures

FIGURES 1 – 7. Ruizantheda centralis n. sp. male: 1, head, frontal view; 2, antenna; 3, T 7, dorsal view; 4, S 4, ventral view; 5, detail of median apical projection of S 4, showing row of specialized setae; 6, genital capsule, ventral view (right), dorsal view (left): prl, basal proyection of the retrorse lobe of the gonocoxite, rl, retrorse lobe of the gonocoxite, gs, gonostylus; 7, S 7 and S 8 fused, ventral view. Scale lines: Fig. 1, 0.3 mm; Fig. 2, 0.5 mm; Figs. 3 – 7, 0.2 mm.