Chalepogenus roitmani Roig Alsina

Torretta, Juan Pablo, Marrero, Hugo J. & Alsina, Arturo Roig, 2011, Chalepogenus roitmani Roig Alsina (Hymenoptera: Apidae: Tapinotaspidini): description of the male and new geographical records for the species, Zootaxa 2797, pp. 21-24 : 21-23

Chalepogenus roitmani Roig Alsina

( Figs. 1–5 )

Chalepogenus roitmani Roig Alsina, 1999: 77

Description. Male. Total length 8.7–9.5 mm (n=5), forewing length 7.0– 7.8 mm (n=5).

Coloration. Head black, with following yellow marks: labrum, clypeus (except tentorial pits), lower paraocular area (from clypeus to level of antennal socket), supraclypeal area (varying from central mark to band between subantennal sutures), small median mark on malar area, scape, except longitudinal dark band on inner surface, and basal mark on mandible. Pedicel dark; flagellum dark brown with yellowish-brown lower surface. Thorax and propodeum blackish, except anterior yellow mark on tegula and in some specimens small yellow spot on pronotal lobe. Coxae and trochanters blackish, forefemur blackish with yellow apex, middle femur with basal half blackish and yellow apex, and hind femur yellow with basal fifth or less blackish. Tibiae and tarsi yellow, except foretibia with inner longitudinal dark band, hind tibia with dorso-apical dark area, and hind tarsus brown. Metasoma blackish with discal yellow marks broadened laterally on T1–T7, as follows: T1 and T2 with lateral mark, marks on T2 larger, confluent in some specimens, T3–T7, with transverse bands. S6 with yellow lateral mark. Wings membrane strongly infuscate; veins dark brown and pterostigma yellowish brown.

Vestiture. Hairs whitish on labrum, clypeus and supraclypeal area, yellowish-brown on rest of head. Labrum and apical half of clypeus with dense, plumose hairs, basal part of clypeus, face and vertex with mixed plumose and simple long hairs, denser around antennal sockets, longer ones 2.2–2.5 times as long as DF. Thorax, propodeum and metasoma with light yellowish-brown hairs. Scutum with two types of hairs: with very short, homogeneous, dense, felt-like hairs, and with intermixed erect, simple, long hairs, as long as 0.7–1.2 times DF. Scutellum with similar pubescence, but with distinct lateral tuft. Hairs long on pleura, 2.2 times DF, shorter on propodeum and metaposnotum (1.5 times DF). Terga hairy, without glabrous areas, T2–T3 with short lateral hair-bands; T4–T6 with dense apical hair-bands. S2–S6 with median bands of very dense hairs, occupying most of visible part of sternum, except base and narrow apex, that on S2 extended on central two thirds, and those on S3–S5 more extended laterally; hairs of bands longer laterally and curved towards middle; S6 with hairs shorter, restricted to apex.

Structure. Median ocellus in frontal view at level of line uniting top of eyes. Vertex not elevated behind ocelli. Proportion of scape, pedicel and first three flagellomeres, 2.7:0.7:1:0.5:0.8. Preapical tooth of mandible with rounded apex. Pygidial plate with well defined, carinate margins. S7 with single lateral lobe, bearing rounded apico-mesial projection ( Fig. 4 ). S8 between apical lobes not membranous. Genital capsule ( Fig. 5 ) with median dorsal sinus narrow, apical projection of parapennial lobe absent, gonostylus 0.7 times as long as gonocoxite.

Material studied. New records: ARGENTINA. Buenos Aires, 5 females, Chascomús, 19-XI-2002, M. Devoto (on Cypella herbertii ). 5 females, Chascomús, 9-XII-2002, M. Devoto (on Cypella herbertii and Sisyrinchium platense ). 1 female, Ea. Las Chilcas, Pila, 25-XI-2008, H. J. Marrero (on Lotus glaber ). 1 female, Ea. San Claudio, Carlos Casares, 3- XII-2008, G. Cilla (on Taraxacum officinale ), 1 male, Ea. Las Chilcas, Pila, 2-II-2008, H. J. Marrero (on Sisyrinchium platense ), 1 male, Ea. Las Chilcas, Pila, 30-XI-2008, H. J. Marrero (on Vernonia sp.), 1 male, Ea. Las Chilcas, Pila, 10- XII-2009, H. J. Marrero (on Acmella decumbens ). 1 female, Ea. Las Chilcas, Pila, 10-XII-2009, H. J. Marrero (on Cypella herbertii ). 1 male, Ea. Las Chilcas, Pila, 11-XII-2009, H. J. Marrero (on Lotus glaber ). 1 female, Ea. Las Chilcas, Pila, 10-XII-2009, H. J. Marrero (on Cypella herbertii ). 1 male, Ea. Las Chilcas, Pila, 7-I-2010, H. J. Marrero (on Cypella herbertii ). 4 males, Ea. Las Chilcas, Pila, 28-XI-2010, J.P. Torretta (on Sisyrinchium platense , Lotus glaber , Acmella decumbens ).

In the key to species of Chalepogenus of Roig Alsina (1999), males of C. roitmani run to couplet three, agreeing with the characteristics indicated for the male of C. muelleri . The key can be amended in the following way:

3 Pubescence of scutum very short, squamiform, felt-like, with scattered long hairs. Lower paraocular area with yellow mark from clypeus to antennal socket ..................................................................................................................3’ - Pubescence of scutum long and dense. Lower paraocular area dark or, at most, with small yellow mark next to clypeus .......................................................................................................................................................................... 4 3’ Smaller species (5.5–6.2 mm long). Legs dark reddish-brown, without yellow marks. T1–T2 without yellow marks. Scape dark ......................................................................................................................................................... muelleri - Larger species (8.7–9.5 mm long). Femora and tibiae extensively marked with yellow. T1–T2 with yellow marks. Scape extensively yellow .................................................................................................................................. roitmani

Bionomical observations. Males and females were observed copulating on the flower heads of Acmella decumbens [ Asteraceae ], corroborating the sex association based on the morphology. Females of C. roitmani were observed collecting oils on flowers of Cypella herbertii and Sisyrhinchium platense [ Iridaceae ] in the Estancia Las Chilcas, Department of Pila in the province of Buenos Aires.

Discussion. The muelleri species-group of Chalepogenus is supported by two apomorphic characters of the males: the seventh sternum has a single lateral lobe, which bears an apico-mesial projection, and the parapennial lobe of the gonocoxite is reduced (Roig-Alsina 1999). The male of C. roitmani presents both features, indicating that the species belongs in the group, being closely related to C. unicolor and C. muelleri . Moreover, C. roitmani and C. muelleri share strongly dichromic sexes, not known in other Tapinotaspidini , suggesting that they are sister species within the group. The pygidial plate of the male C. roitmani is margined by a distinct carina, both apically and laterally, as in the other two species of the muelleri group. The lack of defined lateral margins on the pygidial plate has been indicated by Roig Alsina (1999) as one of several apomorphic features that unite all other species of Chalepogenus , suggesting that the muelleri group represents the basal lineage of the genus.

The new flower records and observations corroborate the previous association ( Roig Alsina 1999) of this oilcollecting bee with plants of the family Iridaceae as oil sources.

Figures

FIGURES 1 – 5. Chalepogenus roitmani. 1. Male, habitus, dorsal view. 2. Male, metasoma, dorsal view. 3. Female, metasoma, dorsal view. 4. Male, S 7, ventral view (right half). 5. Male, genital capsule, dorsal view (left half). Scale lines. Fig. 1: 3 mm; Figs. 2 – 3: 1 mm; Figs. 4 – 5: 0.1 mm.