Thread subject: Diptera.info :: Californian Ephydridae to ID

Posted by Roger Thomason on 11-07-2023 15:56
#1

Found just off the beach at Alameda in San Francisco, I'm thinking it might be Mosillus bidentatus going by images in BugGuide.

Regards

Roger

Posted by Roger Thomason on 11-07-2023 15:56
#2

2

Posted by Tony Irwin on 11-07-2023 21:18
#3

I think Mosillus is a good call, but not sure about the species.

Posted by John Carr on 11-07-2023 22:37
#4

The key by Mathis et al. (1993) says

1. Mesonotum extensively microtomentose, whitish; middle tibia mostly yellowish orange; 2nd abdominal tergum with median depression narrow, linear posteriorly ... 2
1. Mesonotum very sparsely microtomentose to mostly bare, shiny and frequently microsculptured; middle tibia mostly black; 2nd abdominal tergum with median depression broad basally, narrowly triangular ... Old World species: bracteatus, subsultans, and asiaticus
2. Face bare except for microtomentose antennal grooves; parafacial with 2 small microtomentose spots at level of antenna; 5th tergum with dorsomedial area microsculptured, bearing setulae ... M. bidentatus (Cresson)
2. Face, including antennal grooves, extensively microtomentose; parafacial with 1 vertically elongate microtomentose area; 5th tergum with dorsomedial area densely microtomentose ... stegmaieri Wirth from Eastern USA and tropics and tibialis Cresson widespread in North and Central America


Posted by Roger Thomason on 14-07-2023 06:32
#5

Thanks for the confirmation of genus Tony, and John for the keys. I'm afraid my eyes glaze over while reading keys though, but thanks anyway. The abridged version on the BugGuide page suits me better " Face with a pair of small, white spots between antennae and eyes. Other North American species have a large white area instead of small spots".
https://bugguide....ew/1011495

Regards

Roger