Microdon (Chymophila) angulatus Hull, 1943

Reemer, Menno, 2013, Taxonomic exploration of Neotropical Microdontinae (Diptera: Syrphidae) mimicking stingless bees, Zootaxa 3697 (1), pp. 1-88 : 83-85

Microdon (Chymophila) angulatus Hull, 1943

Figs 267–269 .

Microdon angulatus Hull, 1943: 715 .

Studied type specimens (see notes below). HOLOTYPE. Male. Label 1 (round, blue): "Ega"; label 2: " PARATYPE / Microdon / angulata / Hull"; label 3: " HOLOTYPE / Microdon angulatus / Hull, 1943". Coll. CNC. PARATYPE. BRAZIL. Male. Label 1: " Paratype "; label 2: "Amazon 66 53"; label 3: " Holotype Microdon angulata Hull ". Coll. BMNH.

PARATYPE. BRAZIL. Male. Label 1: " Paratype "; label 2: "Amazon 66 53"; label 3: " Paratype Microdon angulata Hull ". Coll. BMNH.

Notes on type specimens. The description of Hull (1943) was based on a male holotype, labelled "Ega" and two male paratypes, labelled "Amazon, 66 53". The holotype is now in the CNC collection, carrying a yellow label stating that it's a paratype. The BMNH collection holds the two paratypes, one of which is labelled as holotype. As Hull (1943) stated that the holotype is from Ega, the specimen in the BMNH collection labelled as holotype can not be regarded as such. A new red label with the text " HOLOTYPE / Microdon angulatus / Hull, 1943" has been added to the CNC specimen by the present author.

Redescription

Adult male. Body size: 11 mm.

Head. Face occupying 1/3 of head width in frontal view; shining dark brown; white pilose, except for a dense brush of black pile at anterior oral margin. Gena blackish brown. Oral cavity with lateral margins produced. Frons blackish, white pilose; vertex blackish, black pilose. Occiput black; black pilose dorsally, white pilose ventrally. Eye sparsely but clearly pilose. Antennal fossa about as wide as high. Antenna with scape dark brown, pedicel pale brown except for dark brown base; ratio of scape:pedicel as 4:1. [N.B.: in the specimen labelled as ‘holotype’ the antennae are missing, while in the other paratype the basoflagellomeres are missing. Hull (1943) describes the antennae as follows: “Antennae very slender, a little longer than the depth of the face. Third joint about as long as the first joint and two-and-one-half times as long as the second; all of the antennae brown in colour, except blackish base of the second joint. Arista slender, not quite as long as third joint.”]

Thorax. Scutum black with dark brown lateral margins; black pilose, with pale pile along transverse suture. Postpronotum and postalar callus dark brown, black pilose. Scutellum dark brown, black pilose basally, pale pilose apically; with two apical pale brown calcars about 1/3 as long as length of the scutellum, with mutual distance about 1/2 the width of the scutellum; scutellum concave between calcars, but not sulcate. Anterior and posterior part of anepisternum divided by a clear sulcus; black pilose anteriorly and posteriorly, these patches of pilosity dorsally connected. Anepimeron black pilose. Katepisternum black pilose dorsally. Katatergum and anatergum pilose and microtrichose, respectively. Other pleurae bare. Calypter greyish yellow, halter brownish.

Wing: brown infuscated, especially in and posterior to costal cell, with pales part in apical 1/4. Entirely microtrichose.

Legs: Blackish, with tarsi brown: first tarsomeres dark brown, last two tarsomeres yellowish brown. Legs black pilose, except yellow pilose dorsally on last two tarsomeres and ventrally on all tarsomeres. Hind tibia and first tarsomeres of hind tarsus very dense and long pilose, with longest pile longer than width of tibia. Coxae and trochanters brownish, with mostly pale and some black pile.

Abdomen. Blackish brown. Tergite 1 with anterior half concave, laterally with black pile. Tergite 2 wider than thorax; with long pale pile laterally and anteriorly, short black pile posteriorly. Tergites 3 and 4 fused, with suture vaguely visible over most of width; wider than thorax; short black pilose, except longer pale pilose laterally. Abdomen laterally strongly depressed between 3rd and 4th tergite. Tergite 4 with very large lateral bulges. Sternites blackish brown and pale pilose. Genitalia as in fig. 269 (based on the paratype in the BMNH collection labelled as ‘holotype’).

Female. Unknown

Notes. In its wing venation (shape of vein M1; fig. 267) and structure of the male genitalia (fig. 269), this species clearly fits into the concept of Chymophila Osten Sacken, 1875 , a subgenus of Microdon (see Reemer and Ståhls 2013a). As far as currently known, this is the only stingless bee mimicking species belonging to this subgenus.

Figures

FIGURES 267 – 271. 267 – 269. Microdon (Chymophila) angulatus male (paratype). 267. habitus dorsal; 268. habitus lateral; 269. genitalia lateral. Peradon chrysopygus female (holotype), habitus dorsal. Photo: Luca Picciau (MRSN). 271. Number of species (y-axis) per number of known specimens (x-axis) for the genera revised in the present paper.