Megachile (Chrysosarus) concava Mitchell, 1930

Durante, Silvana, Torretta, Juan Pablo & Colombo, Maria Guadalupe, 2014, Descriptions of unknown sexes, new geographical records, and host associations for two South American species of Megachile (Hymenoptera: Megachilidae), Zootaxa 3814 (1), pp. 133-138 : 134

Megachile (Chrysosarus) concava Mitchell, 1930

( Figs. 1–4 )

Megachile concava Mitchell, T. B. (1930) : 242. Male. Villarrica, Paraguay.

Megachile (Chrysosarus) concava ; Moure et al., 2007: 955; Raw, 2007: 33; Moure et al., 2012.

Description. Female. (Nine individuals) Total length 11–12.50 mm. Head, maximum width 4.55 mm, maximum length 3.25 mm; forewing length 9.20 mm. Integument. Black ( Fig. 1 ) except: dark reddish brown flagellum and tarsus; brown on legs, ferruginous on tibial spurs 1 and pretarsal claws (dark brown apically); dark brown on tibial spurs 2 and 3. Wings yellowish-hyaline; tegula veins and stigma ferruginous. Vestiture. Black and dense ferruginous ( Figs. 1–3 ); upper half of head, mesosoma, inner surfaces of tibiae and T1 ferruginous; basal half of mesosoma and legs white yellowish; clypeus, anterior area of gena and hypostomal area dark brown; legs and T2–T6 black, hind tibiae with brown tomentum; T2–T6 covered with short hairs and terga usually with complete yellow and tomentose bands ( Fig. 4 ); T2–T5 with patch of yellow tomentum, more wide on T3–T5; scopa yellowish on S2–S4, in S3–S4 laterally black and S5–S6 with well dispersed black scopal hairs. Punctation. Integument of the head generally coriaceous, densely punctate; clypeus and supraclypeal area denser puncture, separated by 0.2–0.3 times a puncture diameter; central disc of supraclipeal area impunctate. Mandibles coriaceous, scarcely punctate; vertex small, punctate. Scutum, scutellum and axila with large punctures, punctures separated by 1–2 times a puncture diameter on scutellum and separated by 0.1–0.2 times a puncture diameter on scutellum and axilla. T2–T6 with smaller punctures separated by 2–6.5 times a puncture diameter, more separate medially on T3. Structure. Inner margin of eyes slightly concave above ( Fig. 3 ); paraocular carina present. Proportional length of scape, pedicel and first three flagellomeres 1.00:0.22:0.22:0.26:0.28; distal flagellomere broader than long (0.46:0.22). Interantennal distance subequally to antennoclypeal distance (0.90:0.82), longer than antennocular distance (0.90:0.54), and longer than antennal insertion to median ocellus (0.90:0.60). Clypeus and supraclypeal area nearly flat; apical margin of clypeus as in figure 3; mandible with four teeth, without cutting edge; fourth mandibular tooth as in figure 3. Median ocellus located above supraorbital line; interocellar distance equal to ocellocular distance (0.64:0.64) longer than ocelloccipital distance (0.64:0.52). Gena narrower than eye (0.66:0.90), in lateral view. Scutellum rounded, not protuberant in profile. Metasoma, cordate, T6 straight in profile, dorsally rounded.

Material studied. (Nine females and ten males) ARGENTINA. Ciudad Autónoma de Buenos Aires, 1 female, 08/12/2004, D. Medan leg. ( FAUBA). Formosa, 1 male, Reserva El Bagual, 19/08/2001, Torretta leg. (on Handroanthus heptaphyllus , Bignoniaceae ); 1 male, Reserva El Bagual, 20/08/2001, Torretta leg. (on Fridericia dichotoma , Bignoniaceae ); 1 female, Reserva El Bagual, 08/10/2002, J.P. Torretta leg. (on Handroanthus heptaphyllus ); 8 males and 7 females, Reserva El Bagual, emerged between 08/01/2013 and 31/07/2013, J.P. Torretta leg. (reared from five nests; Torretta & Durante, unpublished information).

Distribution: PARAGUAY. Guairá, Villarrica. ARGENTINA. Santa Fe ( Raw 2007); new records: Buenos Aires and Formosa.

Bionomic observations. Seven females and eight males were obtained from the same trap-nests (Torretta & Durante, unpublished information). Furthermore, males and females were observed hovering around and foraging on flowers of Handroanthus heptaphyllus and Fridericia dichotoma (both Bignoniaceae, Torretta pers. obs.). The two sexes are similar in the color of the flagellum, tibial spurs, tarsi, wing, veins and stigma, body pilosity, and the punctures of vertex.

In the key to the species of Megachile of Mitchell (1930), the females of M. concava run to couplet 94, agreeing with the characteristics indicated for the female of M. diversa . The key can be amended as follows:

94. Fifth sternum with a white apical fascia; terga with fasciae not more than a third the width of each segment..................................................................................................... M. vestis Mitchell - Sterna not fasciate; terga with broad fasciae, covering more than half of each segment............................. 94’ 94’. Mandible, legs and basal segment of metasoma pale ferruginous, terga with very broad fasciae, covering more than half of each segment.......................................................................... M. diversa Mitchell - Mandible, legs and basal segment of metasoma black or dark brown, terga with broad fasciae, covering half of each segment.................................................................................... .. M. concava Mitchell Remarks. Based on Mitchell`s (1930) detailed description it is possible to recognize this species with certainty, in spite we have not seen the type specimen. M. (C.) concava is easily separated from other species of the subgenus by the pale pubescence of the mesonotum [in M. (C.) guaranitica Schrottky , M. (C.) catamarcensis Schrottky the pubescence is dark], by brown legs [in M. (C.) melanopyga Friese it is ferrugineous], by the dark integument of the metasoma [in M. (C.) rufula Friese it is ferrugineous], by the narrow tergal bands [in M. (C.) diversa Mitchell it is very broad, covering over half of each segment] and by the fifth sternum without apical bands [in M. (C.) vestis Mitchell fifth sternum have a white apical band].

Figures

FIGURES 1 – 4. Megachile (Chrysosarus) concava Mitchell. Female. 1, habitus, lateral view. 2, head and mesosoma, lateral view. 3, head, frontal view. 4, metasoma, dorsal view.