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09 de agosto de 2022

Griffiths' Treatment of the Genera of Anthomyiidae in the Nearctic Region Part 1: Introduction

Note: Part 2 will be posted almost immediately after this. these are also my notes, not formal publication, even though this may end up on Google Scholar for some ridiculous reason.

The Anthomyiidae represent one of the most difficult to identify and neglected families of flies. First, recognizing the family itself from other families in Muscoidea can often be difficult. Generic diagnoses primarily describe differences in genitalia, which almost always requires dissection to see in calyptrate flies. References for keying fauna of the larger continents are highly lacking. When present, they are scattered, outdated in nomenclature, and/or perhaps importantly, can be highly inaccessible or expensive to obtain. No comprehensive classification exists for this family, with the few attempts not having substantial grounds in cladistic argumentation. The only molecular and evolutionary study of these flies had not been done since last year (Gomes at el., 2021). For a family that contains species of economic importance, specialized on by the considered founder of modern cladistics Dr. Willi Hennig, not as diverse as better known calyptrate families, and with species primarily inhabiting temperate or arctic regions, they should not be in the state they currently are in.
Dr. Graham C. D. Griffiths from the University of Alberta, to say the least, revised the species of the Nearctic Region in his multi-volume Flies of the Nearctic Region. Before the Anthomyiidae, his work consisted of extensive translations of the systematic works of Hennig, the higher-order systematics of flies, and especially on the taxonomy of Agromyzidae with Dr. Kenneth Spencer. His familiarity with several languages probably made him a great bridge between European and American workers in the systematics of these flies, which was certainly needed. He wrote in his Flies of the Nearctic Region that the species of Anthomyiidae even in the Palearctic were in extensive confusion due to inadequate descriptions and lack of study of the type specimens. This was until Hennig created his monograph of the family in 1967-1976. The state of the family in the Nearctic must have been worse. It still lagged behind the understanding of the Palearctic region at the time. Dr. Hugh Huckett was for 60 years the only taxonomist in North America for the family, and certainly the first and only specialist on them for the region at the time. While his work was actually an improvement over earlier literature, it still had several deficiencies. Many species could not be recognized from descriptions due to lack of information on the genitalia. Association of the sexes was also apparently problematic, so many of the allotypes were not the same species as the holotypes. Griffiths also wrote that Huckett proposed many synonyms for species already described from Europe. Griffiths hoped to further correct these inconsistencies, and he certainly did. Unfortunately, the entire work was not able to be completed as he was diagnosed with throat cancer in 2006 and died 3 years later. The relationships between the genera of Anthomyiidae (probably a key to genera), characterization of the family, a revision of the genus Botanophila, and brief comments on formal nomenclature were intended to be published according to his first volume.
Griffiths was also known for his strong opinions on morphology and phylogeny. He utilized sections and other ranks of aggregate species or groups between genera and species in the Anthomyiidae. Griffiths reasonably remarked that although he believes in these groups, they were not intended to necessarily be included in catalogues in spite of the worries some authors had about the concept of polynomial nomenclature. As for the ICZN, it does not recognize these ranks. They are all treated as names at the level of subgenera (except for the superspecies groups, which are not considered to be genus-group names). However, these names are not available regardless, because they are incorrectly in a binomial format rather than composed of only one word.
All in all, keys to the genera of Anthomyiidae in the Nearctic region are desperately needed and need to be accessible. The Manual of Nearctic Diptera includes a key to the genera of Anthomyiidae of the Nearctic region created by Dr. Hugh Huckett. Unfortunately, it was developed before the publication of Griffith's important monograph of the family, and maybe even in large part before the completion of Hennig's Palearctic version, resulting in the key being highly outdated in terms of nomenclature and classification. The Global Biodiversity Information Facility, Systema Dipterorum, and perhaps other sites include many of these synonyms and their currently valid names which will be helpful in identifying these. The Manual's key includes the genus-group names Circia (=Alliopsis), Chelisia (=Anthomyia), Chiastocheta (the Nearctic species on the Manual are now in Botanophila), Pseudochirosia (=Alliopsis), Eremomyioides (=Eutrichota), Crinurina (=Lasiomma), Macrophorbia (=Lasiomma), Anthomyiella (=Calythea), Neohylemyia (=Leucophora), Proboscimyia (=Leucophora), Pycnoglossa (=Chirosia), Hylemyza (=Hylemya), Ganperdea (=Leucophora), Pegomya of couplet 35 (=Eutrichota), Nupedia (=Pegoplata), Pseudonupedia (=Paradelia), Paraprosalpia (=Alliopsis), Eremomyia (=Eutrichota), Craspedochoeta (=Anthomyia), Acrostilpna (=Lasiomma), Macateeia (=Botanophila), and Pegohylemyia (=Botanophila).
In anticipation of an attempt to reconstruct a more user-friendly key for the Nearctic genera of Anthomyiidae, generic synopses of the Anthomyiidae will first be compiled. I like to imagine the generic synopses proposed by Griffiths hinted at the direction of which he intended his own generic key to go as well. Although many workers think that keys to the genera in this family will unequivocally require genitalia in large part, I don't really think so. Before Griffith's final 2004 volume in his Flies of the Nearctic Region, however, that would have probably been true. Dr. Verner Michelsen did construct a key to the Neotropical genera in the Anthomyiidae chapter of the Manual of Central America published in 2010, and genitalia was not used at all in the couplets.
The higher-order classification of Anthomyiidae is shaky with very minimal proposals having been made, but better than the other calyptrate families. A summary of this matter has been provided by Gomes at al. (2021). Huckett's classification in the Manual of Nearctic Diptera is outdated and untenable. Michelsen (2000) proposed one of the best possible classifications for the family, dividing it into the subfamilies Myopininae, Pegomyinae, and Anthomyiinae, but excluded the genera Phaonantho and Coenosopsia from any subfamilies. I don't currently have access to Michelsen (2000). Gomes et al., (2021) shows that Phaonantho and Coenosopsia are not basal in the family, and formed a relationship with Hydrophoria and Zaphne (unproposed grouping). Another relationship between Calythea, Pegoplata, Enneastigma, and Myopina was recovered ("Myopininae?"). Another for Pegomya, Emmesomyia, Taeniomyia, and obviously Eutrichota ("Pegomyinae"?). Finally, the rest of Anthomyiidae or Anthomyiinae. Fucellia were not sampled, but Hennig suggested a clade consisting of Botanophila, Fucellia, and Chiastocheta. Gomes et al. (2021) also added "Hylemyza" to this relationship. A tribal classification is present in the informal Diptera of the British Isles, which was reviewed by Dr. Michael Ackland. It is remarkably close to what I have imagined would be a good classification, but some of those groups are not monophyletic (for example, Delia in Hydrophoriini). Based on their analyses, a classification could be proposed where Pegomyinae would include tribes Myopinini and Pegomyini (nonetheless, Myopininae could be monophyletic). A new subfamily Hydrophoriinae which could also include Hydrophoriini and Coenosopsiini. Anthomyiinae could be split into tribes Deliini and Anthomyiini. These are not formal proposals. Dolichopodidae: Hydrophorinae and Scathophagidae: Delininae may cause confusion. Additional genera also would be interesting to sample for these molecular studies, especially Parapegomyia and Hylemyia.

Anepimeron - the sclerite on the side of the thorax usually lacking strong setae, located immediately posterior to the anepisternum, above the katepisternum, essentially equivalent to our oblique muscles, same as pteropleuron, pteropleura, pteropleural
Anepisternum - probably the largest sclerite on the side of the thorax, there is a row of strong setae lining the posterior margin of this region, essentially equivalent to our oblique muscles in location
Apical - the tips of the body part, usually furthest away from the body (distal)
Antennae - the parts of the antennae are divided into three segments, the scape, pedicel, and flagellum. The scape is referred to as first antennal article in Griffiths. The pedicel second antennal article. The flagellum in calyptrates, referred to as third antennal article in Griffiths, is composed of a few units known as flagellomeres. These flies evolved to have the first flagellomere absurdly expanded into a bulb-like organ with many names, the first flagellomere, third antennomere, third antennal article, third antennal segment. The remaining flagellomeres became the arista.
Apomorphous - having derived or specialized value
Autapomorphous - being unique to a group, same as constitutive
Basal - (1) located closest to the body (2) an ancient or ancestral lineage; synonym: proximal
Calypters - the flap-like pieces of wing membrane located at the base of the wings, same as squama
Chaetotaxy - the physical characteristics including arrangement of setae on the body
Surfaces of chaetotaxy:
a - anterior
ad - anterodorsal
av - anteroventral
d - dorsal
p - posterior
pd - posterodorsal
pv - posteroventral
v - ventral
Discal - located on the disc or middle of a sclerite, such as discal scutellar seta
Distal - located furthest away from the body
Interfrontal - the middle black to reddish rectangular region on the forehead of the fly between the eyes, there is often a pair of interfrontal setae located shortly anterior to the ocellar setae
Face - the facial region of these flies is considered to be between the ptilinal fissures, usually covered by the antennae, and located between the vibrissa
Frons - the forehead of the fly between the eyes
Katepisternum, katepisternal - "hips" of the fly on the thorax that are over the middle pair of legs, it is located directly over them, there are usually 3-5 strong setae pointing in different directions on this region, same as sternopleura, sternopleuron, sternopleural
Lower crossvein - the vein on the wings that forms the end of a noticeable, sharply, nearly right-angled rectangular region, same as crossvein dm-cu
Marginal - located at the edge of a sclerite
Mentum - a sclerotized region on the proboscis, it excludes the membranous area closer to the chin and the spongy part at the end
Meron - the "hips" of the fly on the thorax that are over the hind pair of legs, located slightly below and in front of the base of the halteres, same as hypopleuron
Notopleura, notopleural, notopleuron, notopleural depression - a sclerite located at the end of the transverse suture on top of the thorax, there are usually only two equidistant pairs of widely separated setae on them, essentially equivalent to our serratus anterior muscles
Parafrontals - the silvery linear area on the head between the interfrontal area and the eyes of the fly. Griffiths considers these to be the same as the parafacials, which is what this region graduates into below the base of the antennae, lateral to the face.
Plesiomorphy - character state found in the ancestor of a group
Posthumerals - Setae between the humeri or the bulged area on the shoulders of the presutural region on the thorax and the presutural dorsocentral setae. The labeling of the presutural area of the thorax is convoluted among taxonomic works. The posthumeral system is much more intuitive than the "presutural anterior intra-alar" system that McAlpine and the Canada JAI Pollenia key uses (and O'Hara agrees). This is because the presutural setae are not neatly organized into rows of setar as well as the postsutural region. It is better to refer to the setae immediately around the postpronota/humeri using a different system than the intraalar/supraalar system. They are used here as a formula "Posthumeral [# of anterior posthumeral]+[# of posterior]" where "anterior posthumeral" are synonymous with inner posthumeral and anterior intra alar. "Posterior posthumeral" are synonymous with outer posthumeral and anterior supra alar.
Postsutural - a line or suture, sometimes incomplete, can be imagined across the thorax, dividing it into anterior and posterior portions. The posterior portion is referred to as postsutural.
Prealar - anterior postsutural supra-alar seta, often located just above posterior notopleural seta
Presutural - a line or suture, sometimes incomplete, can be imagined across the thorax, dividing it into anterior and posterior portions. The anterior portion is referred to as presutural.
Proepisternum - the major sclerite visible in side view on the very anterior portion of the thorax, they're like the collar bones in a human, same as propleural depression
Prosternum - A sclerite over the neck on the underside of the fly, located between two membranous areas between the two fore coxae
Pulvilli - the tarsal pads
Sclerite - a chitinized plate or region on the body, usually used to describe these parts of the thorax, and usually gray-colored
Scutellum - the shield-like sclerite noticeable on the back of the fly between the wings in top view
Subcosta - on the anteiror margin of the wing, it is the second most notable vein to reach the wing margin
Synapomorphy - a character shared by the ancestor of a taxon
Symplesiomorphy - character with the value ancestral for the family and shared by several groups, usually referred to as groundplan, but that word here may also refer to plesiomorphy
Tarsomeres, tarsal articles - the units the feet of the fly are divided into. They can be modified, expanded in size compared to the tarsomeres on the other legs or they may possess long setulae in the males of some species, rarely females
Vibrissae - the two strong setae pointing forward on the face of the fly not on the antennae

Evenhuis, N.L. & Pape, T. (editors). 2022. Systema Dipterorum, Version 3.9., accessed on 4 August 2022.
Gomes, L.R.P., Souza, D.S., Carvalho, C.J.B. de. 2021. First insights into the evolution of neotropical anthomyiid flies (Diptera: Anthomyiidae). Systematics and Biodiversity 19(7): 724-737.
Griffiths, G.C.D. 1983-2004. Anthomyiidae. Flies Nearctic Region 8(2): 1-160 (=no. 1), 1983; 161-288 (=no. 2), 1983; 289-408 (=no. 3), 1984; 409-600, (=no. 4), 1984; 601-728 (=no. 5), 1986; 729-952 (=no. 6), 1987; 953-1048 (=no. 7), 1991; 1049-1240 (=no. 8), 1991; 1241-1416 (=no. 9), 1992; 1417-1632 (=no. 10), 1993; 1633-1872 (=no. 11), 1996; 1873-2120 (=no. 12), 1998; 2121-2288 (=no. 13), 2001: 2289-2484 (=no. 14), 2003: 2485-2635 (=no. 15), 2004.
Holmberg, R.G. 2017. Entomological Society of Canada/La Société d’entomologie du Canada,
Michelsen, V. 2000. Oldest authentic record of a fossil calyptrate fly (Diptera): a species of Anthomyiidae from early Coenozoic Baltic amber. Studia Dipterologica 7: 11–18.
Michelsen, V. 2010. ANTHOMYIIDAE (ANTHOMYIID FLIES). In: Brown, B.V., Borkent, A., Cumming, J.M., Wood, D.M., Woodley, N.E. & Zumbado, M.A. (Eds.), Manual of Central American Diptera. Vol. 2. NRC Research Press, Ottawa, pp. 1271-1276.

Posted on 09 de agosto de 2022, 10:03 PM by aispinsects aispinsects | 0 comentários | Deixar um comentário

Griffiths' Treatment of the Genera of Anthomyiidae in the Nearctic Region Part 2: The Pegomya-Group

Griffiths covered this group in the first few volumes of his work, which were published between 1983 and 1986.

1. Genus Pegomya

Griffiths' Notes:
"The context of the genus Pegomya in my present sense agrees with that proposed by Suwa (1974: 231), differing from Hennig's (1973) concept through the exclusion of his "connexa-group". The structure of the male genitalia in the species included in that group indicates that some belong to Eutrichota in Suwa's expanded sense and some to a new genus to be described shortly by Michelson or myself...
...I have been in some doubt whether to recognize Emmesomyia (including Taeniomyia) as a full genus or as a subgroup of Pegomya. Michelson has informed me (in correspondence) that he finds a difference in the articulation between the bases of the gonostyli which suggests that Emmesomyia is the sister-group of Pegomya in the present sense; and that enlargement of the male acessory glands is a constitutive (autapomorphous) character of Pegomya lacking in Emmesomyia. This evidence suggests that separation of Emmesomyia from Pegomya as a full genus is justified...
...The frons width is sexually dimorphic (narrower in the male) in all species of Pegomya. Interfrontal setulae are normally lacking in males of all species with the exception of P. convergens Huckett. In the females interfrontal setae may be present or absent, even within series of the same species (so that this character is not reliable for identification). The mentum [or prementum in today's terms] is rather short in all species (at most 0.4 times as long as head height). The thoracic chaetotaxy is unremarkable, with 1+2 posthumerals in the groundplan (less frequently 1+1); none of the species have setulae on the prosternum, propleural depression [or proepisternum], hypopleuron [or meron], pteropleural [anepimeral] or notopleural area (apart from the usual two long notopleural setae); the scutellum is finely pubescent ventrally in all species, bearing on its dorsal surface two marginal pairs of setae and usually a shorter discal pair (sometimes weakly differentiated). The wing venation varies between species in little except the degree to which the lower cross-vein is sinuate; in all Nearctic species (but according to Hennig not in the European P. fuscinata Tiensuu) the lower surface of the costa bears additional short setulae below the main marginal series of of short spinules. The spine before the distal costal break (at the end of the subcosta) is normally also rather short, not much stronger than the other spinules along the basal sections of the costa. The pulvilli are sexually dimorphic, enlarged to a varying degree in males but always small (at most half as long as the 5th tarsal article) in females. The hind tibiae lack apical pv setae...
...Naturally some of the common characters just mentioned are omitted from the species descriptions, since they do not provide any discrimination between species. Much caution is needed in using colour as a diagnostic criterion in Pegomya, since many species show geographical color variation. In many species the females are paler coloured than the males, but they are never darker...
...My keys differ considerably from previous keys because of my elimination of unreliable colour distinctions and greater use of postabdominal characters...
Following Hennig (1973) the genus Pegomya is divided into two subgroups (here ranked as subgenera) of about equal diversity (Pegomya sensu stricto and Phoraea). The subgenus Pegomya in my present sense consists solely of species with leaf-mining larvae..."

Characterization Tables:
Griffiths then includes two characterization tables of the species and species-groups in the subgenera Pegomya and Phoraea in relation to apomorphous and plesiomorphous characters. Griffiths often divided genera in Anthomyiidae into sections, infrasections, subsections, superspecies, and more. The only photographic character used for subgenus Pegomya is the development of the prealar seta, also known as the anteriormost post-sutural supra-alar seta. In most species, this seta is present. The prealar seta being absent is considered apomorphous and the prealar seta being normal present is considered plesiomorphous. An ambiguous value is said for P. umbripennis. Pegomya (subgenus Pegomya) (section hyoscyami) pribifolensis superspecies, P. (Pegomya) (hyoscyami) alticola, and P. (Pegomya) (section minuta) are said to be apomorphous for the prealar seta here.
The only photographic character used for subgenus Phoraea is the size of the lower squama, also known as the lower calypters, in relation to the upper calypters. In most species, these calypters are apparently smaller in area compared to the upper calypters. The lower calypters being larger is considered apomorphous and the lower calypters being smaller is considered plesiomorphous. Only Pegomya (section geniculata) winthemi superspecies and P. (geniculata) unicolor are said to be apomorphous for the prealar seta here.

My comments:
These include the leaf mining "root maggot flies" in the subgenus Pegomya many of you are familiar with. They are not as popular, well known, and perhaps they are even arguably not as commonly encountered as their other infamous distant cousins the Agromyzidae. I am not as familiar with the leaf mining aspect of flies, so I have no comments on their host specificity, but Griffiths says their primary host association is that of the botanical group known as "Centrospermae" or Caryophyllaceae, Amaranthaceae, Portulacaceae, etc. The subgenus Phoraea mostly includes species with mycophagous lifestyles. Others have lifestyles not known or are stem-borers like in the P. rubivora section.
Griffiths pretty much covers about all the characters we can use to recognize the genus. The longest aristal hairs are not longer than the width of the first flagellomere. The vibrissa do not usually have setulae behind the vibrissa like Eutrichota and some species in other genera do. Most species have 1+2 posthumeral setae. The anepisternum is either with or without at least one anterodorsal seta on the corner below the anterior notopleural seta. The prealar can be further defined as being not only present in most species but also, when present, usually noticeably shorter than the length or size of the notopleural setae. The hind tibiae are with 1-3 pd, usually with 2 pd, although 1 only in Pegomya notabilis. Neither sex has any pv setae on the hind tibiae, apical or not apical. Mid tibiae in both sexes with or without an av, exclusive of apical bristle, but usually with 1 pd. Femora and tibiae mainly yellowish. Tarsomeres normal in female. Costal setulae are as Griffiths describes; short and weak, including the pair of spines before the distal break (or subcostal break). A substantial number of species do not have much yellow on the body, with even the legs dark.

2. Genus Emmesomyia

Griffiths' notes:
"Constitutive (autapomorphous) characters by which Emmesomyia differs from Pegomya are as follows: The lower squama is enflarged, distinclty larger in area than the upper in all species. (In the groundplan of Pegomya the lower squama is smaller in area than the upper, but a similar enlargement occurs in members of the P. winthemi subsection)...
...In most species of Emmesomyia the head is sexually dimorphic, with the eyes only narrowly separated and the upper parafrontal setae (ors) lacking in the male (Fig. 470). This head dimorphism is associated with dimorphism with leg structure (enlarged pulvilli in males, presence of strong av seta near base of F2 [mid femora] in females. However, in a remarkable new species (described as E. megaloceros [= Taeniomyia megaloceros]) the eyes are widely separated in the male (Fig. 471) as in the female and the legs are also identical in both sexes (with pulvilli less than half as long as 5th tarsal article as normally in females).
The presence or absence of interfrontal setae in females may, as in Pegomya, not be a constant character and should not be relied upon for diagnostic purposes. The mentum is rather short in all species (at most 0.4 times as long as head height). The thoracic chaetotaxy is characterized by strong development of the acrostichals (in well separated rows with additional shorter setulae in between), 1+1 or 1+1(2) posthumerals (lower posterior weak or absent) and relatively short prealar. Malloch (1917b) based his concept of Emmesomyia on the presence of a pteropleural seta, but this is not a groundplan character of the genus as a whole. This seta is (no doubt primitively) lacking in subgenus Taeniomyia, and is not entirely constant in its presence in subgenus Emmesomyia [either]. No species have setulae on the prosternum, propleural depression, hypopleuron, or notopleural area apart from the usual two long notopleural setae); the scutellum is finely pubescent ventrally in all species, and in most (except E. megaloceros) bears two long marginal pairs of setae (and sometimes a shorter discal pair). The lower surface of the costa bears additional short setulae below the main marginal series of short spinules (as also in Pegomya). The hind tibiae lack apical pv setae. There are three spermathecae, as normally in Calyptratae.
...The constitutive characters of subgenus Emmesomyia [now just genus Emmesomyia], so far as can be judged on the basis of Nearctic species, are the presence of a pteropleural seta and the absence of a setula on the postgonite. However, it should be noted that occasional individuals lacking the pteropleural seta can be found."

Characterization Tables:

My comments:
The genus Emmesomyia represent a good example of a genus that would have probably been difficult to recognize or identify based on current keys but is quite distinctive. These flies appear to approach a slightly more muscid appearance, looking quite similar to the genus Phaonia. Griffiths noted the strong development of the acrostichals which is definitely something that is noticeable in photos and a worthwhile difference from other genera. I have to add the arista should always be moderately long haired to long haired (missing in the holotype of E. longiforceps). The third antennal article is at least 2.5 times as long as wide in all the Nearctic species. This is longer than the vast majority of the other Anthomyiidae in this region. The prealar or anterior post-sutural supra-alar seta is very short. The dorsal surface of the scutellum is bare centrally to largely setulose. The Manual of Central America explains that the basal node of vein R2+3 is with short, fine setulae on dorsal and ventral surfaces. As far as their color goes, they are similar to the genus Pegomya, with extensive yellow at times.
I have found E. socialis in Florida to be not uncommon, typically perched on foliage in many different habitats. One of them I noticed had a strange, long, filament distinctly attached to the same point on the costa of both wings. Another strange thing I noticed was that I only see females (probably); I have never seen a (at least noticeably) male in real life or online. Other species in North America should also not be uncommon.

3. Genus Taeniomyia

Griffiths' notes:
"The above synonymy calls for little explanation except to to note that the customary restriction of Taeniomyia to what is hre called subgenus Taeniomyia does not accord with Stein's (1919) original concept, which also included species of subgenus Emmesomyia. Stein's concept of Taeniomyia largely coincided with the concept of genus Emmesomyia here proposed. Malloch's prior proposal of the name Emmesomyia was unknown to Stein at the time of writing.
...The pteropleural seta characteristic of subgenus Emmesomyia s.s. is absent in Taeniomyia. All females of Taeniomyia which I have examined possess strong spines on the posterior margins of the 6th tergite and 6th sternite (Fig. 502-503). These provide ready diagnosis, since they can be seen without extending the ovipositor. I interpret the development of these spines as a constitutive (autapomorphous) character of Taeniomyia. How the spines are used during oviposition (or larviposition?) is unknown."

Characterization tables:

My comments:
This genus was treated as a subgenus of Emmesomyia by Griffiths. They are primarily Neotropical in distribution. There are about 3 species in the genus with only 1 known to occur north of Mexico in Arizona (T. spinulosa, but Griffiths describes all of them in his work). Michelsen (2010) treated it as a full genus. Gomes et al. (2021) found that it was actually more closely related to Pegomya than Emmesomyia (however, the two diagrams provided in that paper have completely different relationships between all those genera; in any case, the discussion of that clade clearly distinguishes Pegomya+Taeniomyia).
My comments on morphology for the genus Emmesomyia are the same for Taeniomyia. The exceptions are obviously the absence of an anepimeral seta, the species are more yellow than those in the genus Emmesomyia, T. megaloceros is even almost entirely yellow, the third antennal is shorter in T. megaloceros, 1.5-2 times as long as wide, but this species is not known north of Mexico anyway. The only species in this region as said earlier is T. spinulosa, which I will as a result try to briefly describe/transcribe here:
Male: thorax and abdomen finely dusted, sometimes ground color becoming yellowish on humeri, postalar calli, and tip of scutellum, abdomen shining over largely yellowish. Mid and hind legs almost entirely yellowish.
Male eyes separated narrowly to distance up to width of ocellar tubercle. Genal setae in 1 row. Arista with long pubescence. Third antennal article 2.8-3.2 times as long as wide. 1+1 posthumerals. Prealar very short. Scutellum largely setulose but with bare central area at base.
Leg chaetotaxy: T1 with 1 ad, 1 p; T2 with 1 pd, 2 p; T3 with 1 av, 3 ad, 2 pd (in which lower is outstandingly long)
Wings slightly yellowish tinged. Costal spinules slightly strong.
Female: same as male except abdomen largely shining orange and yellow. 6th tergite entire, with strong spines and dense setulae posteriorly.

4. Genus Parapegomyia

Griffiths' notes:
"[See Griffiths' Notes for genus Pegomya] The present taxon was recognized as the Pegomyia connexa group by Huckett (1941: 14). Hennig (1973) broadened the concept of the Pegomya connexa group to include Arctopegomyia (here considered a subgenus of Eutrichota), but offered no convincing evidence that the group in this expanded sense is monophyletic. Suwa (1974), evidently influenced by Hennig's concept, included members of the P. connexa group in the original sense along with Arctopegomyia in Eutrichota, but offered no detailed justification. In my opinion the Pegomyia connexa group in Huckett's (1941) original sense should not be included in Eutrichota, since it lacks the constitutive (autapomorphous) characters of that genus. The new genus Parapegomyia is therefore proposed. The following is the formal description:
Frons width sexually dimorphic (narrower in the male); interfrontal setulae absent or at most weakly developed (in some females). Palpi not expanded. 1+1 posthumeral setae; notopleural area without setulae additional to the usual two long notopleural setae; prealar seta longer than posterior notopleural; scutellum with discal pair of setae much shorter than the two long marginal pairs, with fine pubescence on its ventral surface; propleural depression, prosternum, pteropleuron and hypopleuron bare. Lower surface of costa with additional short setulae below the main marginal series of spinules; lower squama smaller in area than upper. Hind tibia without apical pv. Pulvilli sexually dimorphic, enlarged in males but less than half as long as 5th tarsal article in females...
...The life history of Parapegomyia is entirely unknown. The presence of strong hooked spines on the ovipositor suggests that the eggs (or larvae) may be inserted into an elastic medium."

Characterization tables:

My comments:
These confused flies were considered Arctopegomyia by Hennig until Griffiths pointed out two overlooked heterogenous taxa in this group: one being Eutrichota (Arctopegomyia) and another being the group containing Pegomya connexa, which did not share the synapomorphous characters for the genus Eutrichota according to Griffiths, and is this genus Parapegomyia here. Later on, Barták et al. (1990) synonymized Parapegomyia with Eutrichota. I don't have access to that paper, unfortunately. Griffiths had a massive amount of evidence to support the split. There were numerous differences in genitalic structure, especially in the structure of the female's ovipositor which was, in fact, unique in Anthomyiidae. The antennae are longer than almost any other species of Eutrichota in the region, the third antennal article at least 2.5 times as long as wide. There are no additional setulae behind the vibrissa as in Eutrichota. A distal anteroventral seta on the mid femora is absent, which is only shared by 1-2 species in Eutrichota. The arista is plumose. The 1+1 posthumerals differs from the 1+2 groundplan of Eutrichota. Some females may apparently have a short pair of interfrontal setae, which are invariably absent in Eutrichota. Whatever the case for the synonymy may be, it must be very convincing. Systema Dipterorum considers it to be Eutrichota.
The genus is made up of two species-group taxa: Parapegomyia socculata connexa and Parapegomyia socculata socculata. However, the statuses of these is another issue. After Griffiths' treatment, Pont and Ackland (2009) wrote the valid name of Parapegomyia socculata connexa as Parapegomyia connexa. "P. connexa" and P. s. socculata according to Griffiths both occur in vicariance with P. s. socculata in northwest Canada and Alaska and "P. connexa" as a quite frequently collected and widespread eastern species. He wrote that they only differ in color, mainly the legs. No structural characters were recorded in the description for P. socculata socculata, as Griffiths referred to the other taxon for those. The ovipositor in P. socculata socculata was not examined. P. socculata connexa is the overwhelmingly commoner species. I'm not as sure which side to take here, but I feel that Griffiths' treatment of the two as simply subspecies was just fine. No taxonomic complex has been proposed.
The key for both subspecies on Griffiths involves entirely color. In P. socculata connexa, the coxae and femora are largely yellowish (except for brownish basal patches on coxae) and the processes on the 5th sternite of the male is yellowish. In P. socculata socculata, these are largely infuscated to dark.
Griffiths described both color and structure of P. socculata connexa. These flies are somewhat distinctive to the trained eye. They are shining with their thorax blackish and laterally grayish in some angles. They are very similar to Eutrichota lipsia but lack expanded tarsal articles and differ in the antennae.
The male frons is also wider, with the eyes separated by about the width of the ocellar tubercle. The third antennal article is 2.5-3 times as long as wide. The arista has long pubescence. Presutural acrostichals consist of 3 pairs in rows becoming rather widely separated anteriorly, with a few shorter setulae in between. The dorsal surface of the scutellum is mostly bare with only a few scattered setulae on the sides. Katepisternum with 1+2 setae. Costa with marginal spinules weak except for pair before subcostal break which are about twice as long as the costal width. The lower crossvein is slightly sinuate. Hind tibia with 2-3 posterodorsal setae and 0-2 posterior to posteroventral setae. Wing membrane extensively yellowish tinged.

5. Genus Eutrichota

Griffiths' notes:
"I accept the expanded concept of Eutrichota proposed by Suwa (1974), within which Eremomyia and Eremomyioides must obviously be included on morphological grounds. Suwa omitted the last two names from consideration because no included species occur in Japan. Hennig (1976a: lxiii) partly accepted Suwa's proposal (with the inclusion of Eremomyia and Eremomyioides), but suggested the retention of Arctopegomyia in the sense of his Pegomya connexa group as a separate genus on the grounds that it is not finally settled whether this taxon is more closely related to the rest of Eutrichota in Suwa's sense or to Pegomya.
I have concluded that the solution of this disagreement between Suwa and Hennig lies in recognizing that there are two heterogenous taxa included by Hennig (1975) in his Pegomya connexa group. One of these, equivalent to Arctopegomyia in Ringdahl's (1973) original sense, appears correctly included in Eutrichota, having ovipositor structure abd male genitalia very similar to those of the rest of the genus. Suwa's synonymization of Arctopegomyia with Eutrichota can thus be upheld. There remains the taxon containing connexa Stein (=socculata Zetterstedt) and its close relatives, whose inclusion in Eutrichota by Suwa can indeed be challenged since it is not supported by synapomorphous characters. This taxon has been described above as the new genus Parapegomyia...
...There is considerable variation in the degree of sexual dimorphism in the frons width in Eutrichota. In some species the eyes of the male are only very narrowly separated (by less than the width of the anterior ocellus), while there are at least two species (E. inornata and E. melanderi) in which the frons is broad and fully feminine in appearance (with differentiation of ors and ori). Since a complete series of intermediate conditions is shown, the separation of the Palearctic type-species E. inornata as a distinct genus, by some authors (such as Seguy 1937) even placed in a different tribe, is obviously untenable. In other respects E. inornata is in no way remarkable, having male genitalia typical of subgenus Eutrichota s. s. (as here defined). I include it in the E. praepotens superspecies on account of the plumose arista, basal epiphallus, and expanded female fore tarsal articles.
Interfrontal setae are invariably lacking both in male and female Eutrichota. The presence of additional setulae (spiniform in some species) behind the vibrissa (in addition to the usual marginal setae below it) is useful for separating Eutrichota and Pegomya when sorting collections. The mentum is relatively short (0.3-0.4 times as long as head height) in all Nearctic species of Eutrichota. In the groundplan (and most species) there are 1+2 posthumeral setae and a long prealar (longer than the posterior notopleural). Variation in the thoracic setae and setulae is of considerable diagnostic value, since the genus includes subgroups with unusual proliferation of setae and setulae (most extensively in the E. cylindrica superspecies) as well as one in which the chaetotaxy is somewhat reduced (the E. affinis section). The lower surface of the costa bears additional short setulae below the main marginal series of spinules in all species. The lower squama is smaller in area than the upper in all species. The leg chaetotaxy varies considerably between the various subgroups and is of diagnostic importance. It seems likely that the presence of a distal anteroventral seta on f2 is a groundplan character, since this is found in Arctopegomyia [see Griffiths' notes and my comments for Parapegomyia] as well as in some species of all sections of Eutrichota s. s. Such a seta is never present in Pegomya and Parapegomyia. Huckett has also used the development of the apical tibial setae for diagnosis, which is indeed of some vlue but not as constant in many species as he assumed. In my descriptions I refer to the development of an apical pd on t1 (between the invariably present apical ad and p), which seems the most useful character involving the apical tibial setae. The hind tibiae lack an apical pv seta. The pulvilli are sexually dimorphic, enlarged to a varying degree in males but always small (at most half as long as the 5th tarsal article) in females. In the females of some species the 2nd to 4th tarsal articles (but not the 5th) of the fore legs are expanded to some degree.
As in Pegomya, the females of some species of Eutrichota are paler coloured than the males but never darker. Life histories are known only for a few members of subgenus Eutrichota s. s. (see below). The genus appears confined to the Palearctic and Nearctic Regions, where it occupies the full ranges of habitats from hot desert through temperate and boreal forest to arctic and alpine tundra."

Characterization tables:
Griffiths includes one characterization table for the whole genus that includes the subgenera Arctopegomyia and Eutrichota. The characters that distinguish the subgenera are mainly genitalic. There are no ranks established within subgenus Arctopegomyia besides the species. In contrast, subgenus Eutrichota is divided into the triticiperda, affinis, apicalis, and praepotens sections with E. substriatella as a species sola. The affinis section has further an affinis subsection, but no other sections have any ranks besides the "superspecies" and below.
Unlike for most of these tables in Griffiths' work, many photographable characters are used in this table. These include the sexual dimorphism in eye height, development of the costal spinules and setulae, vestiture of the notopleuron, length of the discal setae on the scutellum, the shape of the arista, vestiture of the thoracic sclerites (prosternum, proepisternum, meron), the degree of shininess of the first and second antennal articles (scape and pedicel), the development of the prealar seta, and modifications of the fore tarsomeres. The main important points will be explained here and others as comments of mine. The Eutrichota affinis section is separated from all other species of Eutrichota almost unequivocally by the lack of a prealar seta. These flies seem to have it reduced to a setula whose base is marked by a dark spot noticeable in many photographs. In the other species, this seta is long, at least longer than the length of the notopleural setae, and there is no in between. In the E. obversa "superspecies" in the triticiperda section, species may have the notopleural area are with setulae in addition to the 2 setae. This also occurs in all E. (section apicalis) incompleta superspecies, part of E. (apicalis) albidosa, all E. (section praepotens) humeralis superspecies, all E. (praepotens) cylindrica superspecies, and all E. (praepotens) costalis. The same species may also have large discal setae on the scutellum, the pair being over half as long as the marginal pairs. Otherwise, the variations with this character are part of E. (triticiperda) obversa superspecies, all E. (apicalis) incompleta superspecies, all E. (apicalis) albidosa, part of E. (apicalis) apicalis, part of E. (apicalis) flavicans superspecies, and all of E. (praepotens) humeralis superspecies. The arista is quite shortly branched in all the known Nearctic species. The Palearctic E. (praepotens) praepotens superspecies has it plumose but they are not known to occur here. All of the E. cylindrica superspecies uniquely have a hairy proepisternum, and also prosternum and meron. All of the E. triticiperda section have the antennal scape and pedicel shining in contrast to the pruinose third antennomere, along with several other species in subgenus Eutrichota, but not in subgenus Arctopegomyia. Finally, females may have tarsomeres 3 and 4 expanded, and this occurs in all E. (Arctopegomyia) labradorensis, all of E. (Arctopegomyia) partita, and all of the E. praepotens section except for E. costalis, which was only tentatively included in that section by Griffiths.

My comments:
Griffiths characterized this variable genus quite well. Arctopegomyia is often considered a junior synonym of Eutrichota rather than a subgenus. This is probably not supported by enough evidence (Xue et al., 2010). Many cite Suwa's (1974) synonymy of Arctopegomyia in the 21st century but Griffiths' treatment was made well after Suwa's. Griffiths provided much evidence for his treatment based on the aedeagus and thus examination of material.
The subgenera are difficult to separate from each other in the absence of distinctive characters, which are usually abundant in the subgenus Eutrichota. Females in both subgenera may have modified fore tarsomeres. Subgenus Arctopegomyia do not have many distinctive characters. There only 4 species in the subgenus. E. (Arctopegomyia) abradorensis (range Alaska to New Hampshire) can be a very pale-colored species, supposedly entirely shining yellow in the female. Species can have 2-4 posterodorsal setae on the hind tibiae. The males are holoptic but the frons width is variable. The arista has very short pubescence. The third antennal article is 1.7-2.5 times as long as wide, covering the extreme long variation for the genus. Additional setulae behind the vibrissa and marginal row are present. The mid femora always has at least one distal anteroventral seta. The scutellum is largely setulose dorsally. Legs are yellow to black. Life histories of Arctopegomyia are not known.

Barták, M., Michelsen, V., Rozkošný, R. 1990. New records of Anthomyiidae from Czechoslovakia, with a revised check list of Czechoslovak species (Diptera). Scripta Facultatis Scientiarum Naturalium Universitatis Purkyniensis Brunensis 20(9–10): 439–450.
Evenhuis, N.L. & Pape, T. (editors). 2022. Systema Dipterorum, Version 3.9., accessed on 4 August 2022.
Gomes, L.R.P., Souza, D.S., Carvalho, C.J.B. de. 2021. First insights into the evolution of neotropical anthomyiid flies (Diptera: Anthomyiidae). Systematics and Biodiversity 19(7): 724-737.
Griffiths, G.C.D. 1983-2004. Anthomyiidae. Flies Nearctic Region 8(2): 1-160 (=no. 1), 1983; 161-288 (=no. 2), 1983; 289-408 (=no. 3), 1984; 409-600, (=no. 4), 1984; 601-728 (=no. 5), 1986; 729-952 (=no. 6), 1987; 953-1048 (=no. 7), 1991; 1049-1240 (=no. 8), 1991; 1241-1416 (=no. 9), 1992; 1417-1632 (=no. 10), 1993; 1633-1872 (=no. 11), 1996; 1873-2120 (=no. 12), 1998; 2121-2288 (=no. 13), 2001: 2289-2484 (=no. 14), 2003: 2485-2635 (=no. 15), 2004.
Holmberg, R.G. 2017. Entomological Society of Canada/La Société d’entomologie du Canada,
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Pont, A.C. & Ackland, D.M. 2009. The types of Anthomyiidae (Diptera) in the Museum fur Naturkunde Berlin, Germany. Zoosystematics and Evolution. 85: 5-56.
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Xue, W., Dong, W., & Bai, S. (2010). A study on the genusEutrichota(Diptera: Anthomyiidae), with descriptions of three new species from China. Oriental Insects, 44(1), 77–90.

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