Melitoma ameghinoi (Holmberg)

Schaller, A. & Roig-Alsina, A., 2019, The nesting habits and flower relationships of the bee Melitoma ameghinoi (Holmberg) (Hymenopteraı Apidae) ı with notes on its taxonomy and distribution, Journal of Natural History 53 (27), pp. 1633-1645 : 1638-1640

Melitoma ameghinoi (Holmberg)

Energoponus ameghinoi Holmbergı 1903: 407 – 408 (Lectotype male from Argentinaı

Formosaı Monteagudoı 24-III- 1885ı E. L. Holmberg leg.ı MACNı present designation). Melitoma ameghinoi Roig-Alsinaı 1999: 19 . Moure et al. 2007: 153.

Barcode

Five specimens have been barcoded (Barcode Index Number BOLD:ADL9292)ı and their sequences are publicly available online (project AVSı http://www.boldsystems.org).

Diagnosis

Melitoma ameghinoi is readily distinguished by its colour patternı with fulvous pubescence on the head and thoraxı and broad yellow hair bands on the metasomal terga ( Figure 6 (aıb)). These bands occupy over half of the disc of terga 2 – 4 in the femaleı and of terga 2 – 5 in the male. This colour pattern is common to a large number of species in the genus Ptilothrix ı but it is rare in Melitoma . The only other described species of Melitoma with metasomal yellow hair bands is M. ipomoearum ı which has the bands restricted to the apical third of the terga. The shape and vestiture of the seventh metasomal sternum of the male is diagnostic for M. ameghinoi ( Figure 7 ).

Relationships of M. ameghinoi

Two distinctive species groups can be recognised within Melitoma . One of them includes M. segmentaria ı a species with a broad distribution from the United States to Argentinaı and other well-known species from Northı Centralı and South Americaı such as M. taurea , M. grisella , M. marginella ı and M. nudipes (Burmeister) ı as well as two recently described species from South America with notably modified hind tarsi in the males: M. torquata Roig-Alsina and M. fulviscopis Roig-Alsina. All these species are characterised by the elongate first flagellomere in both sexesı the faded epistomal suture on the upper margin of the clypeusı by glabrousı shiny areas on the posterior part of the pronotum and the anterior margin of the scutumı and by the disc of the male seventh metasomal sternumı which is entireı not incised. All these features are synapomorphies supporting the segmentaria group as a clade. The alternate plesiomorphic conditions are present in the second groupı which includes the South American M. ameghinoi , M. osmioides (Ducke) ı and M. ipomoearum Duckeı as well as some undescribed species. The ameghinoi group may be paraphyletic and represent the basal branches of the Melitoma phylogeny. On the other hand two features of the males suggest a close relationship of these species: a preapical protuberance on the lower outer margin of the hind femurı and the shape of the metasomal sixth sternumı with a median somewhat square apical projection. These two characters would support the M. ameghinoi group as monophyletic. The apomorphic condition for all mentioned characters is interpreted according to the phylogenetic relationships among emphorine genera suggested by morphological studies of Emphorini by Roig-Alsina (1994 ı and unpubl. data).

Type material

Three syntype malesı all in poor conditionı are preserved in MACN from the Holmberg collection. All lack the head and are damaged by anthrenids. The one in best conditionı with most legs and a complete metasomaı is selected as the lectotype and labelled accordingly. Its metasomal tergum 7ı sterna 7 – 8ı and genitaliaı are dissected and preserved in a vialı pinned with the specimen. The three specimens are labelled ‘ Monteagudo/ III-24 – 1885 /male symbolı E.L.H. ’ A fourth pin with the same label indicates that a fourth specimen was completely destroyed.

Distribution

The species is found in the provinces of Chaco and Formosa in Argentinaı and in Asunciónı Paraguay ( Figure 8 ).

Material studied

Argentina Chaco. 1 M Barranquerası 15 .IV .2016 A. Schaller ( MACN); 1 F Barranquerası 19 . IV .2016 A. Schaller ( MACN); 1 M Barranquerası 17 .IV .2016 A. Schaller ( MACN); 1 Mı 1 F Barranquerası 23 .IV. 2016ı A. Schaller ( MACN);1 Mı Barranquerası 24 .IV. 2016ı A. Schaller ( MACN); 1 Mı Barranquerası 9 .XI. 2017ı A. Schaller ( MACN); 1 Fı Isla del Cerritoı 20 .X. 2016ı A. Schaller ( MACN); 1 Mı Isla del Cerritoı 10 .I. 2018ı A. Schaller ( MACN); 2 Mı 8 Fı Zona Monte Altoı Resistencia Chacoı 29 .X. 2016ı A. Schaller ( MACN); 1 Fı 1 M Zona Monte Altoı Resistencia Chacoı 29 .XII. 2016ı A. Schaller ( MACN); 5 Fı 2 Mı camino a la Isla del Cerritoı 11 .I .2018ı 15/19. III. 2019ı A. Schaller ( MACN); 1 Fı Colonia Popular 13 .XI. 2018ı A. Schaller ( MACN) ; Formosa: 1 Mı Monteagudo ( MACN); 1 Mı 1 Fı Laguna Ocaı I . 2008ı G. Galvani ( MACN) ; Paraguay: 2 Mı Asunciónı octubre ( MACN); 1 Mı 1 Fı Asunciónı abrilı G . Galvani ( MACN)

Figures

Figure 6. Melitoma ameghinoi from Chaco. a, male; b, female. Scale: 2 mm.

Figure 7. Melitoma ameghinoi male, seventh metasomal sternum. Scale: 0, 5 mm.

Figure 8. Distribution of Melitoma ameghinoi in Argentina and Paraguay. Type locality (star) and new records (dots).