METOPININAE (Disney & Ellwood, 2001)

Brown, Brian V., Amorim, Dalton De Souza & Kung, Giar-Ann, 2015, New morphological characters for classifying Phoridae (Diptera) from the structure of the thorax, Zoological Journal of the Linnean Society 173 (2), pp. 424-485 : 457-462

SUBFAMILY METOPININAE

No new characters on the thorax pleura were discovered that support the monophyly of the Metopininae , although it is usually considered the least controversial higher group in the Phoridae . Traditionally, this group is based on the presence of an ‘anepisternal furrow’ (e.g. Schmitz, 1929b), a character that we discuss below. The first divergence in the subfamily is between Ctenopleuriphora and Phlebothrix (not sampled here) ( Brown, 2009b), and the rest of the subfamily. We found one apparent character (36) that links all other Metopininae exclusive of these two genera in a monophyletic group (which is also supported by nonthoracic characters, 67, 68).

The Metopininae includes about 180 of the approximately 290 genera of Phoridae . We have observed much unexplored variation in thoracic morphology that will be useful to establish the relationships within the metopinines. Targeting a better understanding of the evolution of these structures at the base of the family, we chose not to explore the group until a later time.

30. Proepimeron: (0) small, (1) greatly expanded ( Fig. 33A–F ).

This feature, diagnostic of the metopinines, has been referred to as ‘anepisternal furrow present’ and is a uniquely derived character of the subfamily. This modification possibly corresponds to the enlargement of the proepimeron dorsally and posteriorly, moving with it the surrounding suture. In platypezids ( Fig. 2) and other brachycerans ( Fig. 1 ), the proepimeron is already fused to the anepisternum, with the suture scarcely visible, which is also the condition in most phorids ( Fig. 33A– C ) except the metopinines. The prothorax pleural suture is just dorsal to the insertion of the forecoxa, the anepisternal furrow being placed more posteriorly. The suture of the ‘anepisternal furrow’, and hence is secondary, but it apparently delimits the proepimeron, which would be greatly enlarged in all metopinines ( Fig. 33D–F ). Another genus of phorids that appears to have a version of this furrow (under light microscopy) is the phorine genus Mannheimsia , but the ‘furrow’ is not visible in our SEMs, differently from true metopinines. We thus conclude that the state in Mannheimsia is not homologous to that found in the Metopininae .

31. Dorsal separation of katepisternum from anepimeron: (0) clearly visible, (1) lost ( Fig. 34A–F ).

This character is in its primitive character state, within the metopinines, in Ctenopleuriphora , Phlebothrix and Brownphora ( Fig. 34A, B ). Its apomorphic condition ( Fig. 34C–F ) is shared by most other metopinines. The plesiomorphic condition is widespread in phorines and other phorids.

Figures

Figure 1 Lateral view of the thorax of Cyclotelus (Therevidae). Abbreviations: AnII, anterior anepisternum II; AnIII, metanepisternum; AnP, posterior anepisternum; Ap, antepronotum; CeS, cervical sclerite; CxI, forecoxa; CxII, midcoxa; Cx III, hind coxa; EsI, proepisternum I; Em I, proepimeron I; Em II (Ae), anepimeron II; Em II (Ke), katepimeron II; Em III, epimeron III; KtII, katepisternum (= mesokatepisternum); KtIII, metakatepisternum; Lt, laterotergite; Md, mediotergite; MeII, meron; Pp, postpronotum; PtII, mesopleurotrochantin; RR, paratergite; ScIII, metascutum; TgII, mesothoracic tegula.

Figure 33 Character 30. Proepimeron small (0); proepimeron greatly expanded (1). A, Chonocephalus. B, Javanoxenia. C, Phora. D, Phlebothrix. E, Beckerina. F, Apocephalus.

Figure 34 Character 31. Dorsal separation of katepisternum from anepimeron clearly visible (0); suture lost (1). A, Phlebothrix. B, Brownphora. C, Beckerina. D, Gymnophora. E, Apodicrania. F, Trophodeinus.