Merodon multifasciatus Curran 1939

Merodon multifasciatus Curran, 1939

Figs 1, 4B, 5B, 6B, 9B, 10B, 11B, 12B, 13D–F, 14B, 15B, 16B, 18B, 21F–H, 25

Merodon multifasciatus Curran, 1939: 8 (type locality: Johannesburg, Republic of South Africa). Merodon apimima Hull, 1944: 40–42 (type locality: Mulanje, Nyasaland, Republic of Malawi).

Diagnosis

Large (10–12 mm) and dark, striped species, with golden-yellow pile on the tip of the abdomen (Figs 5B, 14B). Scutum with conspicuous pollinose vittae (Figs 10B, 14B); metafemur with distinct apical dens on triangular lamina (Figs 6B, 16B); terga 3 and 4 with broad medial pollinose fasciae (Figs 5B, 14B). Similar to M. vittatus Vujić & Likov sp. nov. from which differs in male genitalia with wider posterior lobe of surstyle, slightly curved, almost parallel sided, with rounded apex (Fig. 13D: pl), while male genitalia in M. vittatus sp. nov. with longer and narrower, S-shaped posterior lobe of surstyle, gradually narrowing toward tip (Fig. 7D: pl).

Material examined

Holotype REPUBLIC OF SOUTH AFRICA • 1 ♀; Johannesburg; 26.284° S, 27.982° E; 6000 ft; Mar. 1899; J.P. Cregoe leg.; AMNH.

Additional material

REPUBLIC OF MALAWI • 1 ♂, holotype of Merodon apimima; Mulanje, Nyasaland; 16.015° S, 35.521° E; 22 Apr. 1913; S.A. Neave leg.; BMNH • 1 ♀, paratype of Merodon apimima; same collection data as for preceding; 21 Oct. 1913; labelled as allotype; BMNH • 2 ♂♂, paratypes of Merodon apimima; same collection data as for preceding; 18–30 Apr. 1913; BMNH • 1 ♂, paratype of Merodon apimima; same collection data as for preceding; FSUNS ID 04086; NBCN • 2 ♂♂, paratypes of Merodon apimima; same collection data as for preceding; 2 Jun. 1913; BMNH • 1 ♀, paratype of Merodon apimima; same collection data as for preceding; FSUNS ID 04355; BMNH.

Additional non type material

DEMOCRATIC REPUBLIC OF THE CONGO • 1 ♂; Lualaba River; 7.023° S, 27.046° E; 2500– 4000 ft; 21 Apr. 1907; S.A. Neave leg.; FSUNS ID 03909; NBCN LML-05-3.

REPUBLIC OF SOUTH AFRICA • 1 ♂; Modimolle (former Nylstroom); 24.683° S, 28.416° E; 17 Feb. 1908; unknown leg.; reared from Gladiolus bulb; USNM • 1 ♂; Transvaal, 5 mi (8 km) W of Warmbad; 24–25 Feb. 1968; K.V. Krombein leg.; FSUNS ID 04512; USNM ENT 00036564, USNM 2052372 • 1 ♂; Transvaal, Fortuna Trail, S of Barberton, N slope; 26.009° S, 31.048° E; 8 Apr. 1985; J.G.H. Londt leg.; bushveld; FSUNS ID 04284; NMSA • 1 ♀; Mpumalanga, Emgwenya (Waterval Boven), near Elandsrivier; 25.634° S, 30.326° E; 6 Apr. 2018; Sanja Vujić leg.; FSUNS ZA5_242; FSUNS • 1 ♀; same collection data as for preceding; L,S. Forcada leg.; FSUNS ZA5_243; FSUNS.

Redescription

Original descriptions are insufficient, without any illustrations and based on a single female from South Africa (Curran 1939) and male and female types (Hull 1944).

Length: large species, body 10–12 mm, wing 8–9 mm (n = 5).

Male

HEAD (Figs 4B, 9B, 11B, 12B). Antenna (Fig. 4B) reddish-brown; pedicel elongated, approximately as long as basoflagellomere (relation scape:pedicel: basoflagellomere =1.0: 2.5: 2.5); basoflagellomere concave dorsally, with acute apex; arista light brown to dark brown, thickened basally, 1.6 times as long as basoflagellomere. Face from black to dark brown, covered with gray pollinosity and whitish pile, except on bare medial vitta that occupies ¼ width of face. Oral margin protruded (Fig. 9B). Frons from black to reddish, inflated, covered with gray pollinosity and whitish pile. Vertical triangle and isosceles (Fig. 12B), usually dark brown, predominantly covered with a long, yellow pile. Ocellar triangle equilateral. Eye pile dense, gray, slightly longer than scape. Eye contiguity about 15–18 ommatidia long. Occiput reddish, pollinose, covered with yellow pile.

THORAX (Figs 6B, 10B). Mesonotum black, except postpronotum and posterior margin of scutellum brown-reddish, covered with reddish-yellow pile; scutum with five pollinose longitudinal vittae (as on Fig. 10B). Pleuron black to dark brown, covered with gray pollinosity and the following parts with whitish to yellow 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. Wing hyaline, with dense microtrichia and yellow to brown veins. Calypter pale yellow. Halter with yellow pedicel and capitulum. All three femora dark brown to black; tibiae mostly reddish, medially black to dark brown; tarsi reddish (Fig. 6B). Metatrochanter without calcar. Metafemur moderately thickened, with less developed apicoventral triangular lamina, more or less dentate, the apical dens is distinct (Fig. 6B). Pile on legs predominantly whitish to yellow.

ABDOMEN (Fig. 5B). Black to dark brown. Tergum 1 black, usually pollinosed, covered with short whitish to yellow pile; tergum 2 with pollinose posterior margin and narrow medial fascia (in some specimens interrupted in the middle) covered with whitish pile except posterior half of tergum (between pollinose fasciae) covered with short black pilosity; terga 3 and 4 with pollinose posterior margin and broad medial pollinose fasciae (Fig. 5B); anterior half of tergum 3 covered with short black pile; tergum 4 covered with long golden-yellow pilosity (Fig. 5B). Sterna reddish-brown, covered with white or yellow pile.

GENITALIA (Figs 13D–F, 18B). Posterior lobe of surstyle broad, slightly curved, almost parallel sided, with rounded apex (Fig. 13D: pl); anterior lobe of surstyle undeveloped (Fig. 13D); anterior margin of surstyle angular in lateral view (Fig. 13D: ams); cercus square like (Fig. 13D: c). Hypandrium with theca medially distinctly narrowed (Fig. 13F). Lateral sclerite of aedeagus small (Fig. 18B: s).

Female (Figs 10B, 14B, 15B, 16B)

Similar to the male except for normal sexual dimorphism: metafemur usually with small apical dens on triangular lamina (Fig. 16B); frons with non pollinose medial vitta (Fig. 15B); vertex predominantly covered with black pile.

Remarks

Hull (1944) described Merodon apimima “related to multifasciatus Curran in type of femoral armament and abdominal fascia; distinct in the black front, yellow pilose vertex and, brown humeri, absence of red on second abdominal segment, beside other details of pattern” based on six males and one female. All these characters mentioned in original description can be regarded as intraspecific variability of M. multifasciatus. Based on our study of the type material of both species, we regard M. apimima as a junior synonym of M. multifasciatus.

In the original description of species, Hull (1944) did not state the etymology of the species name, so we cannot conclude whether he treated “ apimima ” as a noun or an adjective. According to the International Code of Zoological Nomenclature (Article 31.2.2) (International Commission on Zoological Nomenclature 1999) if the author does not indicate whether the species name is a noun or an adjective, as in this case, it has to be treated as a noun. When the species name is a noun simple or compound, in apposition, it does not need to agree in gender with the generic name, therefore the original spelling has to be retained (Article 34.2.1). In some references (Smith & Vockeroth 1980; Dirickx 1988) M. apimimus is used because authors considered “ apimima ” to be an adjective. But in Systema Dipterorum (Evenhuis & Pape 2020), which is the most comprehensive database related to the Syrphidae, the original spelling of M. apimima is applied.

Period of flight and distribution (Fig. 1)

This species occurs in Malawi, the Republic of South Africa and the Democratic Republic of Congo. On the basis of our data, the flight period was found to be throughout the whole year. Merodon multifasciatus was found in deciduous forest-woodland savanna and brush-grass savanna.

Larval biology

The material from Nylstroom (17 Feb. 1908) was bred from bulbs of Gladiolus (immature stages undescribed). Specimens collected in Emgwenya (Waterval Boven) (6 Apr. 2018) were found on flowers of different plant species inside a small spot (20 × 40 m) with the natural population of Gladiolus sericeovillosus Hook., along a small periodical spring. It is a strong indication that this plant is the primary host for larvae of M. multifasciatus.

Flower visited

During our fileldwork, adults of M. multifasciatus were observed visiting flowers of Nidorella auriculata DC. in Emgwenya (Waterval Boven) (Fig. 26).