Schizoceratomyia Carrera, Lopes & Lane

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 63-64

Schizoceratomyia Carrera, Lopes & Lane Figs 356-363

Schizoceratomyia Carrera, Lopes & Lane, 1947a: 245. Type species: Schizoceratomyia barretoi Carrera, Lopes & Lane 1947a: 245, by original designation.

Johnsoniodon Curran, 1947: 1. Type species: Johnsoniodon malleri Curran, 1947: 1, by original designation. See Papavero (1962) for synonymy.

Description.

Body length: 4-9 mm. Broadly built flies with long antennae (bifrucate in male) and oval abdomen. Head wider than thorax. Face slightly convex or medially concave; wider than an eye. Mouth parts weakly developed, small; oral opening small and round, with lateral margins not produced. Vertex more or less flat, not strongly produced or convex. Frontal ocellus normal, split in two medially or absent. Occiput ventrally narrow, dorsally weakly widened. Eye bare. Eyes in male not or only slightly converging at level of frons, with mutual distance 3-4 times the width of antennal fossa. Antennal fossa about as wide as high. Antenna longer than distance between antennal fossa and anterior oral margin. Basoflagellomere longer than scape, bifurcate in male, in some species also in female; both branches long pilose, especially on inner side; in one (undescribed) species occupied with more than 20 long, narrow tubercles. Arista in male well-developed (longer than pedicel) or reduced to a small stump (shorter than pedicel); in female well-developed, sometimes almost as long as basoflagellomere and thickened. Postpronotum pilose or bare. Scutellum semicircular; without calcars. Anepisternum convex, sometimes with weak sulcus in dorsal 1/4; pilose on dorsal 2/3 to 3/4. Anepimeron pilose on dorsal 3/4 to 1/4, or only along posterior margin. Katepimeron convex; bare; smooth. Wing: vein R4+5 without posterior appendix; vein M1 straight and perpendicular to vein R4+5, or with weak outward angle in anterior 1/2; postero-apical corner of cell r4+5 rectangular to widely rounded, with or without small appendix; crossvein r-m located between basal 1/8 and 1/4 of cell dm. Abdomen dorsoventrally flattened; more oval, with largest width at tergite 3; 1.5-2 times as long as wide. Tergites 3 and 4 fused. Male genitalia: phallus furcate near apex, straight or apically bent ventrad, projecting not or hardly beyond apex of hypandrium; hypandrium with bulb-like base; epandrium without ventrolateral ridge; surstylus unfurcate, elongate or wide.

Diagnosis.

Vein R4+5 without posterior appendix. Abdomen oval. Antenna longer than distance between antennal fossa and anterior oral margin. Antenna inserted below dorsal eye margin. Vertex more or less flat. Katepisternum bare. Metasternum bare.

Discussion.

Hull (1949) and Papavero (1962) treated Schizoceratomyia as a synonym of Masarygus . See Masarygus for discussion on this synonymy, which is not followed here. These authors, as well as Cheng and Thompson (2008) also considered Johnsoniodon as a synonym of Schizoceratomyia , as is also done in the present paper. Although in the two species originally included in Schizoceratomyia ( Schizoceratomyia barretoi Carrera, Lopes & Lane, 1947 and Schizoceratomyia flavipes Carrera, Lopes & Lane, 1947) the basoflagellomere is bifurcate in the male only, whereas in Johnsoniodon this character is found in the female, these taxa are otherwise very similar.

Apparently, Curran (1947) was unaware of the description of Schizoceratomyia by Carrera et al. (1947a, b) when his description of Johnsoniodon malleri Curran, 1947 was published, as this happened almost simultaneously. According to Van Doesburg (1966), the name Schizoceratomyia was published on the 3rd of July 1947, and Johnsoniodon on 14th of July 1947. Cheng and Thompson (2008) stated that Schizoceratomyia was published on the 12th of July 1947. Regardless of whether the date is 3rd or 12th of July Schizoceratomyia has priority over Johnsoniodon .

Besides Schizoceratomyia malleri (Curran), a furcate basoflagellomere in the female is also found in Masarygus carrerai Papavero, 1962. This species is also included in Schizoceratomyia .

Remarkably, in some specimens of Schizoceratomyia , the frontal ocellus is split in two, strongly reduced or even absent, whereas the posterior ocelli are well-developed. Following present species definitions, different states for this character seem to occur within the same species. However, more taxonomic work at species-level is necessary to establish whether this character state variation is intra- or inter-specific. In most Diptera and other flying insects, all three ocelli are well-developed. Reduced or absent ocelli occur in certain terrestrial insects, like certain ants and cockroaches. Among Diptera , they are partly or entirely absent only in a few groups, apparently mainly in certain nematocerous families and some brachypterous or apterous taxa ( Cumming and Wood 2009). It will be interesting to try to correlate the degree of development of the frontal ocellus to behaviour and life-history of Schizoceratomyia -species; aspects which are currently unknown, unfortunately.

Diversity and distribution.

Described species: 4. Neoptropical. A few undescribed species are known to the first author.