December 04, 2021

November 25, 2021

Identification of the major groups within Platycheirus (males)

The taxonomy of Platycheirus on iNat has recently had a bit of a sort out. The result is the use of the generic/subgeneric framework established by Mengual (2020), and within that the Species groups suggested by Vockeroth and developed by Young, Marshall and Skevington. These Groups are called 'Sections' in iNat, because that is the rank that is available. Within the albimanus Section are the complexes scutatus and clypeatus. So it looks like this:

Genus Pyrophaena (aka granditarsis Group) Holarctic
Genus Eocheilosia New Zealand
Genus Platycheirus Holarctic,Neotropical
Subgenus Tuberculanostoma (formerly a distinct Genus) Neotropical
Subgenus Pachysphyria (aka ambiguus Group) Holarctic
Subgenus Carposcalis (aka stegnus Group) New World
Subgenus Platycheirus Holarctic
Section manicatus Holarctic
Section peltatus Holarctic
Section chilosia Holarctic
Section pictipes Nearctic
Section albimanus Holarctic
Complex clypeatus Holarctic
Complex scutatus Holarctic
Not in a complex Holarctic

(European identifiers in particular should note that the definition of 'Section albimanus' used here still conflicts with the definition sometimes used in Europe i.e. those species with white maculae - as it did before. White spots species are spread through the groups. In the UK for example 4 species are considered albimanus Group in this 'white spots' sense: ambiguus is in Subgenus Pachysphyria, discimanus is in Section manicatus, but the other two (albiimanus + sticticus) are in Section albimanus. This is why the concept cannot be implemented in iNat - the taxa have different parents.)

The morphological delineation of the groups within the genus Platycheirus goes primarily with the modifications of the male foreleg. Here is an attempt at a key to the groups on that basis, largely based on Skevington:

1. a. At least some segments of the male foreleg modified in shape.
b. Male foreleg modified only by the presence of ornamental setae, if at all.
2
4
2. a. Male foretibia unmodified in shape (only tarsi expanded).
b. Male foretibia modified in shape.
Section manicatus
3
3. a. Male foretibia broadening gradually throughout its length.
b. Male foretibia broadened distinctly at the apex only.
Section albimanus
Section peltatus
4. a. Face extended well forwards into a prominent pointed snout, but hardly downwards, and with a prominent tubercle, Males dichoptic.
b. Face not extended forwards into a snout. Males holoptic.
Subgenus Tuberculanostoma
5
5. a. Male forefemur with long curled bristle at the apex.
b. Male forefemur without such a bristle.
Subgenus Pachysphyria
6
6. a. Long curled setae on male forebasitarsi.
b. Without long curled setae on male forebasitarsi.
Section chilosia
7
7. a. Male foretibia without ornamental setae (i.e. leg unmodified).
b. Male foretibia with long posterior setae.
Section pictipes
Subgenus Carposcalis

Posted on November 25, 2021 22:25 by matthewvosper matthewvosper | 0 comments | Leave a comment

October 31, 2021

Palloptera s.l.

This table forms part of a discussion on a flag (https://www.inaturalist.org/flags/542333#activity_comment_f72de246-215c-4f6b-be7a-7f3b2d0ca3d5), but was too large to post there: (Explanations of the justifications are in the flag)

Abbreviations:
Genera:
Palloptera=P, Toxonevra=X and Temnosira=M.
Sources:
SD - Systema Dipterorum
FE - Fauna Europaea
OZ - Ozerov, various papers
MZ - Merz https://www.e-periodica.ch/cntmng?pid=seg-001:1997:70::520
HYH - Han https://www.researchgate.net/publication/264147044_A_Checklist_of_the_Families_Lonchaeidae_Pallopteridae_Platystomatidae_and_Ulidiidae_Insecta_Diptera_Tephritoidea_in_Korea_with_Notes_on_12_Species_New_to_Korea/link/53d6230f0cf220632f3d872c/download
MC - Merz and Chen https://www.e-periodica.ch/cntmng?pid=seg-001%3A2005%3A78%3A%3A437
MS - Merz and Sueyoshi http://www.studia-dipt.de/con91.htm

Species iNat Proposed Genus For Against Justification
albertensis Johnson, 1921 N/A P Nearctic N/A Nearctic
alticola Ozerov, 1994 X X SD, OZ N/A Described by Ozerov - so could be Temnosira
ambusta Meigen, 1826 PM M FE, MZ SD (P), OZ (X) M not recognised by OZ
anderssoni Rotheray & MacGowan, 1999 P P SD, FE N/A Unanimity
basimaculata Czerny, 1934 N/A X OZ, FE, MZ SD (P) Discount SD when alone as (P)
bimaculata Strobl, 1910 P P SD, FE MZ (X) FE vs Merz - X not common
carterosoma Ozerov, 1993 X X SD,HYH, OZ N/A Described by Ozerov - so could be Temnosira - but HYH did not reassign
claripennis Malloch, 1924 P P Nearctic N/A Nearctic
czurkini Ozerov, 1993 N/A M SD OZ (X) M not recognised by OZ - one of two he says are difficult to place
elegans Merz & Chen, 2005 N/A P SD, MC N/A Unanimity
ephippium Zetterstedt, 1860 X X OZ, FE, MZ SD (P) Discount SD when alone as (P)
flava Oldenberg, 1910 N/A P SD, FE, MZ N/A Unanimity
formosa Frey, 1930 P P SD, OZ, FE, MZ N/A Unanimity
gavryushini Ozerov, 2019 N/A X OZ N/A Described by Ozerov - so could be Temnosira
jucunda Loew, 1863 N/A X Nearctic N/A Nearctic
kloiberi Morge, 1967 N/A X MZ SD (P) Discount SD when alone as (P)
kukumorensis Czerny, 1934 N/A P SD, MC N/A Unanimity
laetabilis Loew, 1873 X X OZ, FE, MZ SD (P) Discount SD when alone as (P)
longipennis Czerny, 1934 P X OZ SD (P) Discount SD when alone as (P) - Ozerov only - but he does not mention it as a difficult placement
maculifemur Czerny, 1934 N/A P SD, FE MZ (X) FE vs Merz - X not common
marginata Meigen, 1826 P P SD, OZ, FE, MZ N/A Unanimity
modesta Meigen, 1830 PX X OZ, FE, MZ SD (P) Discount SD when alone as (P)
muliebris Harris, 1780 X X SD, OZ, FE, MZ N/A Unanimity
nigriscutata Ozerov, 1993 N/A M SD OZ (X) M not recognised by OZ - one of two he says are difficult to place
orientata Kovalev, 1972 N/A X OZ, HYH SD (P) Discount SD when alone as (P)
pallens Loew, 1873 N/A X FE, MZ SD (P) Discount SD when alone as (P)
paralia Ozerov, 1993 N/A X SD, OZ N/A Described by Ozerov - so could be Temnosira
quinquemaculata Macquart, 1835 PX X OZ, FE, MZ SD (P) Discount SD when alone as (P)
saltuum Linnaeus, 1758 PM M FE, MZ SD (P), OZ (X) M not recognised by OZ
scutellata Macquart, 1835 P P SD, FE, MZ N/A Unanimity
septentrionalis Czerny, 1934 N/A X MZ SD (P) Discount SD when alone as (P)
setosa Melander, 1913 N/A P Nearctic N/A Nearctic
shakhadarana Ozerov, 2010 N/A X SD, OZ N/A Described by Ozerov - so could be Temnosira
shatalkini Ozerov, 1993 N/A M SD OZ (X) M not recognised by OZ
similis Johnson, 1910 N/A X Nearctic N/A Nearctic
simillima Merz & Sueyoshi, 2002 N/A M SD, MS N/A Unanimity
striata Merz & Sueyoshi, 2002 N/A X SD, MS N/A Unanimity
subarcuata Johnson, 1921 M M Nearctic N/A Nearctic
subusta Malloch, 1924 P P Nearctic N/A Nearctic
superba Loew, 1861 N/A X Nearctic N/A Nearctic
terminalis Loew, 1863 N/A P Nearctic N/A Nearctic
trichaeta Ozerov, 1993 N/A M SD OZ (X) M not recognised by OZ
trimacula Meigen, 1826 PX X OZ, FE, MZ SD (P) Discount SD when alone as (P)
umbellatarum Fabricius, 1775 P P SD, OZ, FE, MZ N/A Unanimity
usta Meigen, 1826 P X OZ, FE, MZ SD (P) Discount SD when alone as (P)
ustulata Fallén, 1820 P P SD, OZ, FE, HYH, MZ N/A Unanimity
venusta Loew, 1858 N/A X OZ, FE, MZ SD (P) Discount SD when alone as (P)

Posted on October 31, 2021 21:00 by matthewvosper matthewvosper | 0 comments | Leave a comment

October 27, 2021

Thoughts on the iNat taxonomy of Platycheirus

This post forms part of a discussion on a flag (https://www.inaturalist.org/flags/496291#activity_comment_9906ca40-8da7-489f-bcda-e6c0516f5b16) - but I couldn't embed the spreadsheet there

This covers just over 130 species - there are said to be around 220 in total. It should include all of the Nearctic (North of Mexico) and all of Europe except muelleri and laskai.

SOURCES:
General:
Mengual https://brill.com/view/journals/ctoz/89/2/article-p210_210.xml#R000026%20R000088%20R000111

Young/Marshall/Skevington https://www.mapress.com/zt/article/view/zootaxa.4082.1.1/4574

SOURCES:
General:
Mengual https://brill.com/view/journals/ctoz/89/2/article-p210_210.xml#R000026%20R000088%20R000111
Young/Marshall/Skevington https://www.mapress.com/zt/article/view/zootaxa.4082.1.1/4574

For peltatus group
van Steenis – (considered as a subgroup of albimanus group = Subgenus Platycheirus)
https://www.researchgate.net/publication/269107486_Description_of_and_key_to_the_European_females_of_the_Platycheirus_peltatus_sub-group_Diptera_Syrphidae_with_description_of_the_male_and_female_of_P_islandicus_Ringdahl_1930_statn
Limited to Europe

For scutatus group
Doczkal - https://www.zobodat.at/pdf/Volucella_6_0023-0040.pdf
Limited to Europe
plus YMS for atlasi (North African)

For clypeatus group
Ball and Morris British Field Guide (see comments in post)
and Haarto
https://www.researchgate.net/publication/281206992_The_description_of_the_female_of_Platycheirus_troll_Mutin_Diptera_Syrphidae_with_a_preliminary_key_to_the_Northern_Palaearctic_females_of_the_Platycheirus_clypeatus_group
Covers Whole Palearctic - according to title implication but I don’t have access
And
van Veen field guide for angustipes
and
Dipterists digest No 5 1990 Speight

For ambiguous group
Barkalov - as ‘Subgenus Pachysphyria’ http://kmkjournals.com/upload/PDF/EEJ/17/eej17_6_466-510_Barkalov.pdf covers whole of Russia
and Nielsen - as 'ambiguus group' https://www.zobodat.at/pdf/Volucella_7_0001-0030.pdf covers Europe

for manicatus group
Nielsen and Barkalov - https://www.researchgate.net/publication/319312480_A_revision_of_and_key_to_the_Holarctic_and_Oriental_Platycheirus_manicatus_group_species_Diptera_Syrphidae
Covers Holarctic and Oriental species
Plus YMS for sticticus (see tree p98) EDIT: although YMS resolve it with other species in manicatus, it has an expanded male fortibia, and is not listed as manicatus group by Nielsen and Barkalov above - so it is placed in albimanus group.

For a couple of oriental and Asian species see also
http://www.entomologi.no/journals/nje/2016-2/pdf/nje-vol63-no2-169-174-nielsen.pdf for albotibeticus and formosanus
https://www.researchgate.net/publication/330319469_The_species_of_the_genus_Platycheirus_Lepeletier_Serville_1828_Diptera_Syrphidae_from_Taiwan_with_a_discussion_on_intersex_specimens for perpes
https://www.researchgate.net/publication/316505699_New_material_of_Central_Palaearctic_Platycheirus_Diptera_Syrphidae_with_description_of_three_new_species for dudkoi, latens and transbaikalicus

Posted on October 27, 2021 23:23 by matthewvosper matthewvosper | 6 comments | Leave a comment

October 14, 2021

Eristalis: Distinguishing males of E rupium and E jugorum

Some time ago I was working on a key to European Eristalis (still working on it every now and then!). It seems a good way of learning new criteria for distinguishing the species, and the keys I know, excellent as they are, are not primed for identifying from photographs (the first couplet is often 'aristae plumose or bare'!) - maybe it will get posted here at some point!

Anyway, I was aware of the black posterior fringe of hairs on the front femora of E jugorum males (a handy way to distinguish from horticola males from the key of van Veen. And while working on the difficult 'yellow-hind-metatarsus group' I became aware that E rupium and E obcura males also have a posterior fringe of black hairs on the front femur. It suddenly dawned on me that a male rupium with a dark hind metatarsus could be very hard to distinguish from a male jugorum if there wasn't a good angle on the face.

Soon after, flo-dycob queried an observation I had identified as a male jugorum, and I knew I'd run into precisely this problem.

Well it's taken a while, but here are some features I think can be used to distinguish male rupium and jugorum. Individually some may be more or less reliable, but I think it's a good package. Comments and corrections most welcome!

jugorum rupium
Face produced forwards and down Face produced down only.
Hind metatarsus black, never yellow, swollen Hind metatarsus black to yellow, not swollen.
Femur 1 with dense posterior fringe of black hairs Femur 1 with sparse posterior fringe of black hairs
Femur 2 with posterior fringe of pale hairs Femur 2 with posterior fringe of black hairs at least apically
Stigma short Stigma elongate
T2 spots occupy almost whole lateral margin when fully formed, inner angle just subrectangular T2 spots end well before the hind margin laterally even when fully formed, inner angle distinctly acute.
T3 pale haired T3 posteriorly extensively black haired.
Frons pale haired (dark ground colour shows through) Frons with black hair.
Subcosta yellowish at base Subcosta brown at base
Scutellum distinctly brighter than scutum Scutellum and scutum not contrasting in colour

I would just add that to me the general appearance of these flies is that male jugorum are rather bright, bushy and tidy flies, whereas male rupium often (but not always) seem rather dull and scrawny.

Posted on October 14, 2021 22:18 by matthewvosper matthewvosper | 0 comments | Leave a comment

October 01, 2021

Dissoptera of the World

Dissoptera is an intriguing mainly Pacific Eristaline genus that caught my attention a few months ago. It is characterised by a strange 'scaly pollinosity' - some of them look like they've been rolling in talcum powder!
The descriptions of all the species are available online, but there doesn't seem to be a key available that includes all seven species. The doc below is an attempt to do that, but there are also links to the scientific descriptions of each species, lest my interpretations be flawed.

Species covered are: D clarkei, gressitti, heterothrix, maritima, palauensis, unicolor and yapensis. D pollinosa and Eristalis flavohirta are synonyms of D heterothrix.

Posted on October 01, 2021 11:13 by matthewvosper matthewvosper | 0 comments | Leave a comment

September 24, 2021

Myathropa of the World

So a tangent to a conversation on this observation https://www.inaturalist.org/observations/95937009 inspired me to do the following! Why not?

The species covered are Myathropa florea, M semenovi and M usta. There is also a note on 'Myathropa' flavovillosa which is also known as Eristalis or Mallota flavovillosa.

Posted on September 24, 2021 23:09 by matthewvosper matthewvosper | 4 comments | Leave a comment

September 22, 2021

Volucella of the West (Europe, Africa and the New World)

So I've been having lots of fun with Volucella recently. The centre of diversity of the genus is in the East, and I haven't got a handle on most of them (yet), but I thought I could deal with the 11 species West of the Urals and produce something. So here is a little key, with some general info, some species info and some slightly iffy but 'characterful' mouse-drawn diagrams! I learned a fair bit doing it and hopefully it's worth sharing - do let me know of any errors/inaccuracies.

(Note: this is also the first time I've tried to use the journal function - let alone embed something, so let's see how this goes!)

The species covered are Volucella actica, bombylans (including forms bombylans, haemorrhoidalis and plumata), elegans, evecta, facialis, inanis, inflata, liquida, pellucens (ssp pelluscens), zonaria (ssp zonaria and beckeri), and there are comments on an undescribed species in North America.

Posted on September 22, 2021 22:05 by matthewvosper matthewvosper | 0 comments | Leave a comment