Megaselia crassipes (Wood)

Disney, R. H. L. & Russell-Smith, A., 2014, Additions to the British list of Megaselia Rondani (Diptera: Phoridae), including two new species, from the crowns of ancient pollarded trees, Journal of Natural History 49 (25), pp. 1599-1626 : 1600-1602

Megaselia crassipes (Wood)

( Figures 1–3 )

Phora crassipes Wood 1909, p. 24

Aphiochaeta dactylata Lundbeck 1920, p. 9 . Schmitz, 1952, p. 359

Aphiochaeta exclusa Lundbeck 1921, p. 134 . Schmitz, 1952, p. 361

Megaselia gargarans Schmitz 1948, p. 393 , syn. n.

Megaselia basiturgida Disney and Durska 2011, p. 528 , syn. n.

Megaselia crassipes was not obtained in the present study but it needs to be distinguished from a new species (described below) that was obtained, and from the addition to the British List.

The recognition of M. crassipes has proved troublesome from the beginning. Lundbeck (1922) only included Wood’ s species in his key to the species of his Group IV. However, he included his M. dactylata and M. exclusa in both the key and the text. Subsequently, Schmitz (1952) synonymised both these species with M. crassipes . The effect of this was to play havoc with Lundbeck’ s key to his Group IV. For example, his first couplet separates those species with long costal cilia from those in which they are short. It is evident, however, that these cilia vary across accepted conventions regarding the boundary between ‘short’ and ‘long’. The failure to appreciate this caused Schmitz (1958) to key out this species in his Abteilung IV, Erste Reuhe. Schmitz and Beyer (1965) then keyed out M. gargarans in Abteilung IV, Zweite Reihe. To add to the confusion, Borgmeier (1968) cited the wrong paper of Schmitz for the synonymy of M. dactylata , but correctly observed that Schmitz (1958) had erroneously referred a photo of the wing of another species to M. crassipes .

The recognition of M. gargarans has also proved troublesome. In the keys to the males of the species of the British Isles ( Disney 1989), it seemingly runs to couplet 81, lead 2, to M. crassipes . Schmitz did not provide a figure of the hypopygium but described the anal tube as being ‘kurz, kaum länger als hoch’, which would immediately exclude M. crassipes . In the keys of Schmitz and Beyer (1965), the males of M. gargarans run to couplet 52 on p. 523. Furthermore, in the text Beyer pointed out that Schmitz’ s description of the anal tube was incorrect, as he reported his measurement of its length-tobreadth ratio as being 8:4. Examination of Schmitz’ s slide mount of a paratype male of M. gargarans (in the Museum Koenig, Bonn) endorses this ( Figure 3 ). Furthermore, it is evident that it is a specimen of M. crassipes at the larger and darker end of the spectrum of variation in this species. Therefore, the synonymy of M. gargarans with M. crassipes is herewith formally proposed. M. basiturgida was described from two similarly darker males, but which are not quite as large as the paratype of M. gargarans . Furthermore, the left hypandrial lobes of these two males are paler than usual. However, in every other respect, they lie within the ranges of variation for M. crassipes . Therefore, the synonymy of M. basiturgida with M. crassipes is also herewith formally proposed. Critical details of M. crassipes are given in Figures 1–2 and its recognition clarified in the revised couplets 79–81 of the key to the males recorded from the British Isles ( Disney 1989) (see below).

Figures

Figure 1. Megaselia crassipes male. (A) Posterior face of front tarsus; (B) left face of hypopytgium. Scale bar: 0.1 mm.

Figure 2. Megaselia crassipes male (synonym of M. basiturgida). (A) Left face of hypopygium; (B) posterior face of front tibia and basitarsus. Scale bar: 0.1 mm.

Figure 3. Megaselia crassipes male (synonym of M. gargarans), left face of anal tube.