Ruizantheda Moure

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 : 63-65

Ruizantheda Moure

Ruizantheda Moure, 1964: 265 . Type species: Halictus proximus Spinola, 1851 , by original designation. Oragapostemon Cure, 1989: 312 . Type species: Halictus divaricatus Vachal, 1903 , by original designation. Synonymized under Ruizantheda by Michener 2000: 372.

The genus Ruizantheda is supported by three putative synapomorphies of the male. The apical margin of the labrum is truncate, without an apical process. The labrum of the male has a developed apical process in species of other genera of Caenohalictina, although it is small in Rhinetula and some Agapostemon ( Janjic & Packer 2003) .

The apical margin of S 4 in Ruizantheda is medially projected, bearing a row of six specialized setae with their apices bent down, forming a rake-like structure. In males of other Caenohalictina the apical margin of S4 is medially concave. The presence of modified setae on S4 is frequent in males of Pseudagapostemon ( Cure 1989) , Dinagapostemon , Rhinetula , and Agapostemon (Agapostemonoides) ( Roberts & Brooks 1987) , but their shape and distribution are different from those of Ruizantheda .

Species of Ruizantheda present a basal projection on the retrorse lobe of the gonocoxite. The genital capsule of all males of Caenohalictina bears a retrorse lobe, variously modified, but no species presents a basal projection similar in shape and position to that of Ruizantheda . The basal projection is rather weak in R. divaricata , as pointed out by Cure (1989: Fig. 13A), but it is strong in R. centralis n. sp. ( Fig. 6 ) and in R. proxima ( Moure 1964: Fig. 3 , erroneously labeled as Callochlora chloris ).

Ruizantheda has in common with species of Pseudagapostemon the simple mandible of the male, and the labrum with the verrucose basal elevation of the female. In Ruizanthedella the mandible of the male is bidentate, and the basal elevation of the female labrum is smooth. Species of Ruizanthedella do not share any of the putative synapomorphies mentioned above for Ruizantheda , although both genera share the same distribution of hair patches on the metasomal terga. Ruizanthedella could be a separate lineage, pending a phylogenetic study including all the genera of Caenohalictina.

Males of the new species have a strongly modified venter of the mesothorax, which is longitudinally concave, and bears an anterior and a posterior tubercle at each side; this area is shiny and devoid of hairs. Ruizantheda proxima has a similar structure of the venter of the mesothorax, but this feature has gone unnoticed, probably due to the long pilosity of this species. Besides the unusual modification of the male mesothorax, both species also share the strong basal projection of the retrorse lobe. These features, unique to these two species, suggest their close relationship.

The presence of hairs on the eyes is variable in Ruizantheda , as it is here understood, similarly to the variation present in Pseudagapostemon . Hairs are conspicuous in R. proxima , weak in R. divaricata , and R. centralis has no distinct hairs. Table 1 provides for an easier comparison of the three species of the genus.

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.

Tables

TABLE 1. Comparative table of characters for the three species of Ruizantheda.

R. proxima	R. centralis n. sp.	R. divaricata
Forewing length (mm) 7.2–7.9	5.5–5.8	5.8–6.3
Depression on anterior deep margin of mesoscutum	shallow	shallow
Central lobes of mesoscutal with angled margins lip	with rounded margins	with rounded margins
Dorsal surface of evenly microareolate metapostnotum, female	rugose-striate, with posterior margin microareolate	strongly rugose-reticulate