Merodon bombiformis Hull 1944
Creators: name: Vujić, Ante
name: Radenković, Snežana
name: Zorić, Ljiljana Šašić
name: Likov, Laura
name: Tot, Tamara
name: Veselić, Sanja
name: Djan, Mihajla
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Syrphidae
Merodon
Merodon bombiformis

description: Merodon bombiformis Hull, 1944
Figs 1, 3C, 4A, 5A, 6A, 9A, 10A, 11A, 12A, 13A–C, 14A, 15A, 16A, 21A–D, 24
Merodon bombiformis Hull, 1944: 42–43 (type locality: Waterval, Republic of South Africa).
Diagnosis
Large, golden species (10–14 mm) with reddish-yellow/golden face and frons (Figs 9A, 11A), lateral sides of scutum (Fig. 10A) and most of terga (Fig. 5A); oral margin reduced (Fig. 9A); antennal segments very short (Fig. 4A), frons inflated (Fig. 9A).
Material examined
Holotype
REPUBLIC OF SOUTH AFRICA • 1 ♂; Waterval; 25.183° S, 29.012° E; 27 Dec. 1898; Distant Collection 1911:383; BMNH.
Additional material
REPUBLIC OF SOUTH AFRICA • 1 ♂; Distant Bush; 28.586° S, 24.658° E; 1182 m a.s.l.; 1911; unknown leg.; NMSA • 1 ♂; Pretoria, Baviaanspoort; 25.664° S, 28.366° E; 1290 m a.s.l.; 15 Feb. 1920; H.K. Munro leg.; FSUNS ID 04277; NMSA • 1 ♀; Natal, Hilton Road; 29.597° S, 30.336° E; 833 m a.s.l.; 22 Dec. 1953; P. Graham leg.; FSUNS ID 04280; NMSA • 1 ♀; Pietermaritzburg; 29.597° S, 30.336° E; 833 m a.s.l.; 5 Nov. 1955; Oosthuizen leg.; reared from Gladiolus bulbs; FSUNS ID 04282; NBCN LML-05-5 • 1 ♂; same collection data as for preceding; FSUNS ID 04276; NMSA • 1 ♀; same collection data as for preceding; 19 Nov. 1955; FSUNS ID 04279; NMSA • 1 ♂; reared from Gladiolus bulbs in Wisley Horticultural Gardens (United Kingdom), which were brought from RSA; Jun. 1956; V.W. Fowler leg.; BMNH • 1 ♀; Transkei, Pitseng Pass, banks from Luzzi River; 30.749° S, 28.299° E; 1633 m a.s.l.; 11 Jan. 1979; J. Londt and B. Stuckenberg leg.; rocky hill and grassveld; FSUNS ID 04278; NMSA • 1 ♂; Eastern Cape, 5 km ENE of Rhodes; 30.783° S, 28.000° E; 2066 m a.s.l.; 5 Feb. 1992; wet stream gully; unknown leg.; FSUNS ID 04275; NMSA • 1 ♀; Eastern Cape, Naudes Nek, near top of pass; 30.759° S, 28.137° E; 2500 m a.s.l.; 6 Feb. 2009; S.I. Morita leg.; FSUNS ID 05724; USNM SMPC_SIM_1844 • 1 ♂; Drakensberg Mountain, Maclear-Naudes Nek; 30.759° S, 28.203° E; 1800 m a.s.l.; 9 Feb. 2016; S. Radenković and N. Veličković leg.; FSUNS ID ZA2_079; FSUNS.
LESOTHO • 1 ♀; Colony of Basutoland, Orange Valley; 29.15° S, 29.03° E; 1500 m a.s.l.; R. Ellenberger leg.; FSUNS ID 03317; MNHN PM-05-46.
Redescription
Original description is insufficient, without any illustrations and based on a single male specimen from South Africa (Hull 1944).
Length: large species, body 10–14 mm, wing 8–10 mm (n = 8).
Male
HEAD (Figs 4A, 9A, 11A, 12A). Antenna (Fig. 4A) very short, reddish to dark brown; scape and pedicel covered with dense, yellow pilosity; pedicel elongated, approximately as long as basoflagellomere (relation scape:pedicel: basoflagellomere =1.0: 1.8: 1.8); basoflagellomere concave dorsally, with rounded apex; arista light brown to dark brown, thickened basally, 5 times as long as basoflagellomere. Face reddish-yellow to dark brown, covered with yellow pollinosity and dense yellow pile, except on bare medial vitta that occupies ¼ width of face (Fig. 11A). Oral margin reduced (Fig. 9A). Frons from black to reddish and golden-yellow, inflated, covered with golden-yellow pollinosity and pile. Vertical triangle isosceles (Fig. 12A), usually reddish to black, predominantly covered with a long, yellow pile. Ocellar triangle equilateral. Eye pile dense, long as the scape, often pale yellow to gray. Eye contiguity about 10–15 ommatidia long. Occiput reddish, covered with yellow pile.
THORAX (Figs 6A, 10A). Mesonotum matte black, except lateral side of scutum including postpronotum and postalar callus, and posterior margin of scutellum reddish-yellow, covered with reddish pile; scutum with five pollinose longitudinal vittae (Fig. 10A). Pleuron covered with gray pollinosity and the following parts with whitish pile: anterior part of proepimeron, posterior part of anterior anepisternum, most of the posterior anepisternum except anterior end, antero-ventral and postero-dorsal part of katepisternum, anepimeron, and metasternum; in some specimens anterior anepisternum and katatergum reddish. Wing hyaline, with dense microtrichia and yellow to brown veins. Calypter pale yellow. Halter with yellow pedicel and capitulum. Legs usually dark brown to black (in some specimens partly reddish), except yellow basal third of tibiae. Metatrochanter without calcar. Metafemur moderately thickened, with less developed apicoventral triangular lamina, not dentate, only the apical dens is distinct, posteriorly oriented (Fig. 6A). Pile on legs predominantly yellow.
ABDOMEN (Fig. 5A). Predominantly reddish-yellow (Fig. 5A). Reddish parts of terga 2–4 covered with yellow pile and dense pollinosity, while dark parts with short adpressed black pile; sterna from yellow to dark brown, covered with white or yellow pile.
GENITALIA (Figs 3C, 13A–C). Posterior lobe of surstyle broad, rounded apically (Fig. 13A: pl); anterior lobe of surstyle undeveloped, virtually absent (Fig. 13A); cercus elongated (Fig. 13A: c). Hypandrium with theca slightly medially narrowed (Fig. 13C: marked with arrow). Lateral sclerite of aedeagus small, quadrilateral (Fig. 3C: s).
Female (Figs 14A, 15A, 16A)
Similar to the male except for normal sexual dimorphism: frons reddish-yellow, with broad goldish pollinose vittae along eye margins; frons completely covered with golden pile (Fig. 15A); metafemur with very small apicoventral triangular lamina; apical dens more or less distinct, slightly posteriorly oriented (Fig. 16A).
Period of flight and distribution (Fig. 1)
The species is distributed in the Republic of South Africa and Lesotho. On the basis of our data, the flight period was found to be from November to February. Merodon bombiformis was collected in different vegetation types, brush-grass savanna, temperate and mountain grasslands and montane foresttundra. On Drakensberg Mountain, at the locality between Maclear and Naudes Nek, it was found near the stream, within bushes of Leucosidea sericea Eckl. & Zeyh. (Rosaceae) and Gladiolus sp. on rocky soil (Fig. 24). Leucosidea sericea grows in Afromontane regions of southern Africa, and is the sole species of this genus (South African National Biodiversity Institute 2004).
Larval biology
Stuckenberg (1956) described the puparia of M. bombiformis, reared from larvae found feeding on commercially grown Gladiolus sp. (Iridaceae) corms. Specimens from Pietermaritzburg (5 Nov. 1955, 19 Nov. 1955) were reared from bulbs of Gladiolus L. too.
Variability of species in the Merodon bombiformis group
A variability in shape of the triangular lamina of the metafemur is present in most of the species of the Merodon bombiformis group, as seen in figures of M. bombiformis (Fig. 21A–D), M. lotus sp. nov. (Fig. 22A–C) M. multifasciatus (Fig. 21F–H), M. nasicus (Fig. 23A–B) and M. zebra sp. nov. (Fig. 22D– F). The triangular lamina is more or less dentate, and the apical dens is distinct (M. bombiformis, M. multifasciatus, M. vittatus sp. nov.) or less distinct, as in M. lotus sp. nov. and M. nasicus. A scutum with conspicuous pollinose vittae, and terga with pollinose posterior margin and medial fasciae, are characters present in most species, except M. lotus sp. nov., characterized by the absence of pollinosity on thorax and abdomen (in females a pair of indistinct pollinose fasciae on tergum 4). Width and shape of vittae and fasciae on scutum and terga vary, especially in M. multifasciatus, M. nasicus and M. zebra sp. nov. The colour of the postpronotum, lateral sides of scutum, frons and face in M. multifasciatus vary from reddish-brown to black. Specimens from the south of the range (RSA) are darker than individuals from northern parts (Central Africa).
Key to the species of the Merodon bombiformis species group
Female of M. vittatus sp. nov. is unknown.
1. Species with reddish-yellow/golden face, frons (Figs 9A, 15A), lateral sides of scutum (Figs 10A, 14A) and most of terga (Figs 5A, 14A); oral margin reduced (Fig. 9A); antennal segments very short (Fig. 4A) ...................................................................................... Merodon bombiformis Hull, 1944
− Species with mostly dark face, frons, lateral sides of scutum and most of terga; oral margin protruded (Fig. 9B–F); antennal segments longer (Fig. 4B–F) ......................................................................... 2
2. Large, dark/brownish species (body length 10–14 mm) with distinct pollinose fasciae on terga 2–4 covered with whitish to yellow pile (Figs 5B–D, 14B–C); tergum 4 with broad medial pollinose fasciae; scutum with five longitudinal pollinose vittae; face dark, mostly covered with gray pollinosity ......................................................................................................................................... 3
− Smaller, black species (body length 6–9 mm) without or with less distinct pollinose fasciae on terga 2–4 (Fig. 5E–F); tergum 4 with less distinct medial pollinose fasciae; scutum without or with indistinct pollinose vittae; face shiny black without pollinosity ...................................................... 5
3. Metafemur with shorter and less dense pilosity, especially ventro-laterally (Figs 6B–C, 16B); eye contiguity longer, more than 15 ommatidia long; anterior margin of surstyle angular in lateral view (Figs 7D, 13D) .................................................................................................................................. 4
− Metafemur with long and dense pilosity, especially ventro-laterally (Figs 6D, 16C); eye contiguity shorter, about 10 ommatidia long; anterior margin of surstyle rounded in lateral view (Fig. 7A: ams) ........................................................................................ Merodon zebra Vujić & Radenković sp. nov.
4. Male genitalia with narrow, S-shaped posterior lobe of surstyle, gradually narrowing toward tip (Fig. 7D) (female unknown) .............................................. Merodon vittatus Vujić & Likov sp. nov.
− Male genitalia with broad posterior lobe of surstyle, slightly curved, with almost parallel sides and rounded apex (Fig. 13D) ........................................................ Merodon multifasciatus Curran, 1939
5. Terga 2–4 without pollinosity, only with medial fasciae of whitish pile (Figs 5E, 14D) (in female a pair of indistinct pollinose fasciae on tergum 4) .......... Merodon lotus Vujić & Radenković sp. nov.
− Terga 2–4 with pairs of medial pollinose fasciae, covered with whitish to yellowish pile (Figs 5F, 14E) ..................................................................................................... Merodon nasicus Bezzi, 1915
description: Published as part of Vujić, Ante, Radenković, Snežana, Zorić, Ljiljana Šašić, Likov, Laura, Tot, Tamara, Veselić, Sanja & Djan, Mihajla, 2021, Revision of the Merodon bombiformis group (Diptera: Syrphidae) - rare and endemic African hoverflies, pp. 88-135 in European Journal of Taxonomy 755 (1) on pages 93-123, DOI: 10.5852/ejt.2021.755.1401, http://zenodo.org/record/5013000