Hoverfly terminology

Part

explanation/ synonym terms

Figures

Abdomen

Abdomen

Posterior division of the body (Thompson 1999).

Figs 1 A, B, 3A, C, D, 32 B, C, 43–51

acetabulum (pl. acetabula)

Head

Rounded membranous area from which antenna protrudes; acetabula can be separated from each other by extension of facial sclerotization [medial sclerotized stripe (Hippa & Ståhls 2005)], which can reach lunule; acetabula can be only partially separated or completely fused, in this case being referred to as the antennal fossa (in narrow sense of Sorkin & Herman 2018).

Figs 10 C, D, 11 A

acropod

Leg

Apical part of tarsomere 5, including arolium, empodium, unguitractor, claws and pulvilli (McAlpine 1981).

Fig. 42 A, B

acrosternum

Abdomen

Anterior sclerite on sternum II, clearly separated by a membranous area from posterior sclerite (McAlpine 1981).

Figs 47 A, B

aedeagal apodeme (McAlpine 1981; Speight 1987)

Male terminalia

see phallapodeme

aedeagal apodeme of Microdontinae (Thompson 1972; Vockeroth & Thompson 1987)

Male terminalia

see lateral strips

aedeagal projections; apex; ventromedial projection; baso-ventral projection; apico-ventral flange (see van Steenis et al. 2016).

Male terminalia

see ejaculatory process

aedeagus (Metcalf 1921; Cumming & Wood 2017)

Male terminalia

see phallus

aedeagus, stem of (van Steenis et al. 2016)

Male terminalia

see phallapodeme

alar callus

Thorax

Supra-alar area, slightly elevated part of the scutum just posterodorsal from the wing base and anterior to the postalar callus, often with short black setae (after Knight & Laffoon 1970).

Figs 28A, 29B, 30 B, 32 A

alula

Wing

A basal lobe along the posterior margin of the wing, located between the calypter and anal lobe (Cumming & Wood 2017).

Figs 34 B, 36 D

alveolus (pl. alveoli)

General

Socket from which macrotrichia arise; sometimes the alveoli give a granulate aspect or "granulate alveoli" to the exoskeleton, like in many Cerioidini (McAlpine 1981).

Figs 4 , 53 C

anal cell (Speight 2020)

Wing

see cell cua; vein CuP

anal lobe (McAlpine 1981; Speight 2020)

Wing

see cell a₁

anal segment

Male terminalia

see proctiger

anatergite (Cumming & Wood 2017),

Thorax

see anatergum

anatergum

Thorax

Posterodorsal plate of the mesothoracic pleuron, posterodorsal to the katatergum; with pile tuft in Allobaccha; part of the lateral postnota of Speight (1987); (Thompson 1999).

Fig. 28A

anepimeron

Thorax

Plate ventral to the wing base, with three distinguishable areas in many species: anterior, posterior and dorsomedial; anterior area always pilose, posterior area sometimes and dorsomedial area pilose in Eristalinus (Thompson 1999).

Figs 23C, 28B, 29A, 30

anepisternum

Thorax

Anterodorsal plate of mesothoracic pleuron, consisting of a flat anterior part and a convex posterior part in many species, although its division is not always clear, see Nausigaster (Thompson 1999).

Figs 28, 29B, 30 A

angle

General

The angle of meeting point of two lines, often used in the wing veins or in the eye contiguity (angle of approximation), indicated by the exact digit or the adjectives right-, acute- or obtuse-angle (Merriam et al. 2022).

Figs 5 , 6 C

angle of approximation

Head

In dorsal view, angle of eyes in holoptic males (Dusek & Laska 1973).

Fig. 6 C

anteclypeus (McAlpine 1981)

Head

see clypeus

antecoxal piece (Shannon 1922b)

Thorax

see metasternum

antenna (pl. antennae)

Head

Sensory organ, anterodorsally placed on the head; formed by the scape, pedicel, postpedicel and arista (Thompson 1999).

Figs 1 A, 18–21

antennal fossa

Head

Fused, or partially fused, membranous acetabula (Sorkin & Herman 2018).

Figs 9 D, 10 A, B, 11 A, C

antennal pit (Shannon 1922a)

Head

see acetabulum

antennal pits (Speight 1987)

Head

see sacculus

antennal process (Vockeroth 1971)

Head

see antennifer

antennal prominence (Curran 1925)

Head

see frontal prominence

antennal sockets (Cumming & Wood 2017)

Head

see acetabulum

antennifer

Head

Anterodorsal extension of head, anterior to frontal prominence, on which the antennae is placed, e.g. Cerioidini; differing from an extended frontal prominence in that the antennifer has the lateral margins parallel both in lateral and dorsal views (Thompson 1999).

Figs 3A, 6 C, 9 C, 12D

antepronotum

Thorax

Anterior part of pronotum, sclerite just above the proepisternum; unpaired anterior sclerite of the prothorax, visible in thorax in frontal view (Speight 1987).

Figs 23A, B, 24,B–E, 25 A, B, D, 26 A–C, 28A, 29, 30 A

anterior (adv. anteriorly)

General

Towards the head end of the fly; opposite of posterior (Thompson 1999).

Figs 1 B–D, 2 , 38 B, 42 A, B, F, G, 54 B

anterior anepimeron

Thorax

Anterior part of the plate ventral to the wing base, always pilose (Thompson 1999).

Figs 29A, 30

anterior anepisternum

Thorax

The anterior, often flat, part of the anterodorsal plate of mesothoracic pleuron (Thompson 1999).

Figs 28, 30 A

anterior cervical sclerite

Thorax

Most anteriorly positioned sclerite of the cervix (Martin 1916; Michelsen 1996).

Figs 23B, 25 B, D, 26 C

anterior mesanepisternum (Speight 2020)

Thorax

see anterior anepisternum

anterior mesocoxite (Speight 1987)

Leg

see disticoxa

anterior mesonotal collar

Thorax

Transverse row of long erect pile on the anterior border of scutum, e.g. Allobaccha, Asarkina, Hybobathus, Ocyptamus (Vockeroth 1969).

Fig. 53 D

anterior ocellus

Head

Single, anteriorly placed simple eye on ocellar triangle (Thompson 1999).

Figs 6 D, 12B

anterior sclerite on sternum II (Speight 1987, Reemer & Ståhls 2013a).

Abdomen

see acrosternum

anterior spiracle

Thorax

Respiratory opening on the anterior part of the pleuron; mesothoracic spiracle (McAlpine 1981).

Figs 23B, 25 D, 26 D, 28B, 30 A

anterior surstylar lobe

Male terminalia

Anterior portion of a bilobed surstylus (Metcalf 1921).

Fig. 54 A

anterior tentorial pit

Head

An invagination of the exoskeleton on the head that serves as an internal attachment site for muscles; visible externally on the boundary between the gena and mala (Thompson 1999).

Figs 10 B, 11 D, 12A, D, 13A, B, 14A, B, 16D, 17C

antero- and posterolateral rows of stout spines (Grković et al. 2015)

Leg

see setose carina

anterocoxal spina

Leg

Anteroventral extension of the coxa; on the metacoxa (Neocnemodon) or on the eucoxa (Platycheirus scutatus) (after McAlpine 1981).

Fig. 42 G

antetergite (Hippa & Ståhls 2005)

Abdomen

see antetergum

antetergum

Abdomen

The median sclerite at the anterior margin of tergum I (Hippa & Ståhls 2005).

Figs 43A, 44 B–D, 45 B, C, 46 C, D

antevertex

Head

Dorsomedial part of head capsule, bordered laterally by eyes, anteriorly by transverse frontal sulcus, posteriorly by transverse vertical sulcus, (Lejogaster metallina). Needs further investigation, might be homologous with vertical rugae in female Lejogaster metallina (Harbach & Knight 1980; Sorkin & Herman 2018).

Fig. 9 B

antevertical sulcus

Head

Transverse sulcus on dorsal part of head capsule bordering the antevertex and the vertex, between the compound eyes, anterior to the ocellar triangle; e.g. male Lejogaster metallina.

Fig. 9 B

apex

General

The end of a structure, most apical point (Thompson 1999; Merriam et al. 2022).

Fig. 2 B

apical (adv. apically)

General

On, or towards, the apex of a structure; opposite to basal (Thompson 1999).

Fig. 1 B

Apical section of vein A₁ (Vockeroth & Thompson 1987)

Wing

see vein CuA+CuP

apically rounded anterior process of mesotarsus (Vockeroth 1990)

Leg

see tarsal lamina

apicoposterior lamina of metafemur (Van Steenis et al. 2017)

Leg

see femoral discus

apicoventral projection (Hippa 1978a)

Leg

see tibial spina

apodemes of epiproct

Female terminalia

Basolateral internal extensions of the epiproct; absent in some Syrphini (Miranda & Moran 2017).

Figs 52A–C

appendage of upper process of hypandrium (van Steenis & Lucas 2011)

Male terminalia

see hypandrial process

appendix

Wing

Small additional vein, arising from another vein or crossvein without connecting to other veins (Thompson 1999); spur (Vockeroth & Thompson 1987).

Figs 35B, C, 36 B, C, 37 B, C

appendix of crossvein dm-m

Wing

Extra longitudinal vein from crossvein dm-m into cell dm, so far only known to be present in Nephentosyrphus capitatus (Hippa 1978b).

Fig. 37 D

appendix of crossvein r-m

Wing

Additional vein from crossvein r-m into cell r₄₊₅ found in Stilbosoma (after Thompson 1972).

Fig. 36 B

appendix of vein M₁

Wing

Additional vein from vein M₁ towards wing margin₁ like in Eumerus, and some Eristalinus species (Ssymank et al. 2021).

Figs 35C, 37 B

appendix of vein M₁₊₂

Wing

Additional short vein from vein M₁₊₂ into cell r₄₊₅; anterior appendix R₄₊₅. Found in Mixogaster and Aristosyrphus (after Reemer & Ståhls 2013a).

Fig. 37 C

appendix of vein R₂₊₃

Wing

Additional vein from vein R₂₊₃ into cell r₂₊₃, in some species of Oriental Sphegina (Asiosphegina) (Hippa et al. 2015).

Fig. 35B

appendix of vein R₄₊₅

Wing

Additional vein from vein R₄₊₅ into cell r₄₊₅; posterior appendix R₄₊₅ (Thompson et al. 2010; Reemer & Ståhls 2013a).

Figs 35C, 36 C

appressed

General

Laying, almost, flat to the body surface, most often used of recumbent pile (Merriam et al. 2022). In Fig. 4 the scale is appressed.

Fig. 4

arcuate

General

Slightly curved, forming an arc; an adjective commonly used for maculae or fasciae (Thompson 1999).

Figs 5 , 44 B, 46 D

arista

Head

Macrotrichia-like structure on postpedicel, derived from modified flagellomeres; in e.g. Psarus abdominalis and Pelecocera) incrassate; in other species positioned apically (Stuckenberg 1999).

Figs 18A, E, 19 A–C, 20 , 21 A, C

aristomere (pl. aristomeres)

Head

Separate segments of the arista (McAlpine 1981).

Fig. 18B

armature

General

All kinds of expansions or projections from the exoskeleton; e.g. spina, lamina, dens etc (Thompson 1999).

Fig. 4

arolium

Leg

Median membranous plate on tarsomere 5, bearing the empodium, connecting the unguitractor with the empodium (McAlpine 1981).

Fig. 42 A

auxiliary vein (Cumming & Wood 2017)

Wing

see appendix of R₄₊₅

auxillary vein in Eumerus (Ssymank et al. 2021)

Wing

see appendix of M₁

auxillary vein in Lyneborgymyia (Ssymank et al. 2021)

Wing

see crossvein r-m₁

axillary lobe (Hull 1949)

Wing

see alula

axillary plates (Sorkin & Herman 2018)

Wing

see axillary sclerites

axillary sclerites

Wing

Irregularly shaped plates at wing base, between the thorax and the basal veins, the first three plates are hypothesised to be detached portions of the base of the veins, while the fourth is supposedly mesonotal in origin (McAlpine 1981; Dessì 2016).

Figs 23D, 29B, 30 B

bacilliform sclerite (Sorkin & Herman 2018)

Male terminalia

see subepandrial sclerite

band (Sorkin & Herman 2018)

General

see fascia

bar (Sorkin & Herman 2018)

General

see macula

bare

General

Surface lacking vestiture, including the wing; if surface lacks macrotrichia but with microtrichia, it should be stated as non-pilose and not bare (narrower specification of Thompson 1999).

Figs 19 A, 20 B, 34 B, 36 A

basal (adv. basally)

General

On, or towards, the base of a structure; opposite to apical (Thompson 1999).

Figs 1 B, 2 B

basalare

Thorax

One of two sclerotized areas at wing base, basalare is anterior and subalare is posterior. The basalare is often only visible as a tuberculate part of the posterior anepisternum (Snodgrass 1935; Crampton 1942).

Fig. 30 B

basale (Speight 1987)

Male terminalia

see epandrium

base

General

Part of a structure that is attached to another more central structure of the body; most proximal point (McAlpine 1981; Merriam et al. 2022).

Fig. 2 B

basicosta

Wing

Anterobasal sclerite of wing, lateral to tegula (McAlpine 1981).

Figs 23D, 33 D, 34 A

basicostale (Cumming & Wood 2017)

Wing

see basicosta

basicoxa

Leg

Dorsobasal part of the eucoxa in the mesoleg (McAlpine 1981).

Fig. 42 F

basiphallus

Male terminalia

Basal part of two-segmented phallus (Cumming & Wood 2017).

Figs 55 C, D

basipulvillus (pl. basipulvilli)

Leg

Paired connecting membrane between fifth tarsomere and pulvillis (McAlpine 1981).

Fig. 42 E

basisternum

Thorax

In frontal view of prothorax, plate between the procoxa (Crampton 1942).

Figs 23B, 25 A, 26 A, C, D

basitarsomere

Leg

First/proximal tarsomere of each tarsus (after Speight 1987).

Figs 38 A, B, 42 B

basitarsus (Sorkin & Herman 2018; Cumming & Wood 2017)

Leg

see basitarsomere

basoflagellomere (Thompson 1999)

Head

see postpedicel

basotarsomere (Thompson 1999)

Leg

see basitarsomere

beaded (Shannon 1926b).

General

see premarginal sulcus

body length

General

Length of the fly from base of antenna to apex of abdomen (Thompson 1999).

see arrowed lines in Fig. 1 A.

bristle (Sorkin & Herman 2018)

General

see seta

buccal arm of tentorial sulcus (Speight 1987)

Head

see subcranial sulcus

buccal cavity (HAO 2010)

Head

see subcranial cavity

bulla (pl. bullae)

General

A blister-like, round shiny swelling, found on abdominal terga in some Afrotropical Phytomia (De Meyer et al. 2020).

Fig. 3D

calcar (pl. calcars, adj. calcarate)

General

Elongate articulated spine-like extension of the exoskeleton, longer than broad. In Syrphidae no articulating extensions of the exoskeleton were found so far. The term as used in Thompson (1999) is here referred to as spina (Sorkin & Herman 2018). Calcar is used in some calyptrate families to refer to a more distinct postero-dorsal seta situated at the metatibia (Cumming & Wood 2017).

not in Syrphidae

callus (Ssymank et al. 2021).

Head

see facial tubercle

callus of 1st tergite of abdomen (van Steenis et al. 2016)

Abdomen

see lateral tubercle of tergum I

callus of sternite I (van Steenis et al. 2016)

Thorax

see metapostnotal “protuberance”

calypter (pl. calypteres)

Wing

A membrane connecting base of wing with thoracic wall, basal to alula; forming two lobes: dorsal calypter (dorsal lobe) and ventral calypter (ventral lobe, thoracic squamula); the calypters fold over each other when the wing is at rest (Thompson 1999).

Figs 23C, D, 27 B, 29B, 30 B, 32 A, D

capitellum (Harbach & Knight 1980)

Thorax

see capitulum

capitulum (pl. capitella)

Wing

Apical and bulbous part of the halter; knob (Sorkin & Herman 2018).

Fig. 23C

carina (pl. carinae, adj. carinate)

General

Sharp low ridge, longer than high, found on the face, legs and genitalia (Harris 1979; Thompson 1999).

Figs 4 , 39 A, D, 41 B–D

cell

Wing

Any area of the wing enclosed by veins, crossveins or the wing margin, named after the vein that forms its anterior margin, written in lowercase (Thompson 1999).

Figs 34 B, 36 D

cell a₁

Wing

Area of the wing posterior to vein A₁; first anal cell. In the old system anal lobe or cell a₂ (McAlpine 1987; Saigusa 2006; Wootton & Ennos 1989).

Fig. 34 B

cell a₁; first anal cell (McAlpine 1981)

Wing

see cell cup

cell a₂; second anal cell (McAlpine 1981)

Wing

see cell a₁

cell bc

Wing

Area of the wing enclosed by vein C anteriorly, crossvein h apically, and vein Sc posteriorly; basal-costal cell (Cumming & Wood 2017).

Fig. 34 B

cell bm

Wing

Area of the wing enclosed by vein M anteriorly, M₄ base and m-cu apically, and vein CuA posteriorly; basal medial cell (Cumming & Wood 2017).

Figs 34 B, 36 D

cell br

Wing

Area of the wing enclosed by vein Rs anteriorly, crossvein r-m apically, and vein M posteriorly; basal radial cell (Cumming & Wood 2017).

Figs 34 B, 36 D

cell c

Wing

Area of the wing enclosed by crossvein h basally, vein C anteriorly, and by vein Sc apically and posteriorly; costal cell (Cumming & Wood 2017).

Figs 34 B, 36 D

cell cua

Wing

Area of the wing enclosed by vein CuA anteriorly and apically, and vein CuP posteriorly; anterior cubital cell. Cell cup in the old system (McAlpine 1987; Saigusa 2006; Wootton & Ennos 1989).

Figs 34 B, 36 D

cell cua₁; first anterior cubital cell (McAlpine 1981)

Wing

see cell m₄

cell cup

Wing

Area of the wing between veins A₁ and CuA+CuP; posterior cubital cell. In the old system cell a₁ (McAlpine 1981; Saigusa 2006; Wootton & Ennos 1989).

Figs 34 B, 36 A

cell cup; posterior cubital cell (McAlpine 1981)

Wing

see cell cua

cell dm

Wing

Area of the wing enclosed by M₄ base basally, the anterior branch of vein M anteriorly, crossvein dm-m apically, and vein M₄ posteriorly; discal medial cell (McAlpine 1981; Cumming & Wood 2017).

Figs 34 B, 36 D

cell m₄

Wing

Area of the wing delimited by crossvein m-cu basally, vein M₄ anteriorly, and vein CuA posteriorly; the cell is open apically; fourth medial cell. In the old system cell cua₁ (McAlpine 1981; Saigusa 2006; Wootton & Ennos 1989).

Fig. 34 B

cell r₁

Wing

Area of the wing delimited by vein R₁ anteriorly and vein R₂₊₃ posteriorly; might be open or closed (when vein R₁ joins R₂₊₃ forming a petiole) before the wing margin; first radial cell (McAlpine 1981; Cumming & Wood 2017).

Figs 34 B, 36 D

cell r₂₊₃

Wing

Area of the wing delimited by vein R₂₊₃ anteriorly, and vein R₄₊₅ posteriorly; second + third radial cell (McAlpine 1981; Cumming & Wood 2017).

Fig. 34 B

cell r₄₊₅

Wing

Area of the wing enclosed by crossvein r-m basally, vein R₄₊₅ anteriorly, vein M₁ apically, and the anterior branch of vein M posteriorly; some groups have a posteroapical appendix on the cell, which is vein M₂; fourth + fifth radial cell (McAlpine 1981; Cumming & Wood 2017).

Figs 34 B, 36 D

cell sc

Wing

Area of the wing delimited by vein Sc anteriorly, and vein R₁ posteriorly; in some groups might be closed apically by a crossvein sc-r; subcostal cell (Cumming & Wood 2017).

Fig. 34 B

cercus (pl. cerci)

Male terminalia

Single-segmented pair of appendages, connected to epandrium, lateral to anus; derived from proctiger; may be strongly developed and/or bearing lobes e.g. Mimocalla (Cumming & Wood 2017).

Figs 48 D, 51 B, 54 A, 55 A, D, 56 A, C, E, 57 A, C, D

cercus (pl. cerci)

Female terminalia

Pair of single segment structures lateral to the anus; membranous or slightly sclerotized, position in relation to epiproct varies among taxa (Miranda & Moran 2017).

Fig. 52

cervix

Thorax

The neck; primarily membranous area between thorax and head (Knight & Laffoon 1970; McAlpine 1981).

Figs 23A, 26 D, 30 B

chaetotaxy

General

The disposition of setae/pile on the body surface, especially on the costal vein of the wings (McAlpine 1981).

Fig. 33 A

chitinous box

Male terminalia

Usually spherical structure at the base of the phallus in Microdontinae; Metcalf (1921) used this term to refer to the basal portion of the phallus in general (Thompson 1969).

Fig. 56 F

chitinous box sensu Metcalf (1921)

Male terminalia

see phallus

cicatrix (pl. cicatrices)

Leg

Sulcus or ridge-like scar on the femur and tibia of many genera within Microdontinae (Hull 1949, see also Harris 1979).

Fig. 40 A

cilium (pl. cilia)

General

Special thick pile found on the occiput in some species, e.g., Ceriogaster. Narrower defined than Thompson (1999).

Figs 4 , 15A

claw

Leg

Paired gripping structure, apico-lateral to fifth tarsomere (Thompson 1999).

Figs 42 A, E

clypeal knob

Head

Tubercle formed by postclypeus, seen in lateral view, dorsal to subcranial cavity and ventral to facial tubercle. Not present in Pipizinae and several Microdontinae. Adjusted from Thompson (1972) and Hippa & Ståhls (2005).

Figs 12B, 14A, D

clypeus

Head

Baso-anterior sclerite of proboscis, located between apical margin of buccal cavity and labrum; divided into postclypeus and anteclypeus in some Syrphidae (e.g. Syrphus); clypeus commonly used as synonym of anteclypeus (Speight 1987).

Figs 16B, D, 17A–C, 22

comb (Sorkin & Herman 2018)

General

see ctenidium

compound eye (Sorkin & Herman 2018)

Head

see eye

copulatory pocket (Hippa 1986)

Female terminalia

see genital chamber

cornea (Sorkin & Herman 2018)

Head

se facet

coronal sulcus (in part, Nayar 1964)

Head

see occipital sulcus

coronal suture (in part, Harbach & Knight 1980)

Head

see occipital sulcus

costagium (Doczkal & Pape 2009)

Wing

see basicosta. Costagium (Séguy 1941; McAlpine 1981) is the base of vein C, between basicosta and crossvein h. In recent Diptera manuals this region is not differentiated from the rest of costa and thus costagium is not a term used in Syrphidae.

coxa (pl. coxae, adj. coxal)

Leg

First, or most basal, segment of the leg, with prefix pro- meso- or meta- (Thompson 1999).

Figs 23A, C, 25 C, 26 C, 27 A, C, 28A, 29A, 30 A, 31 , 32 B, C, 38 A, C, D, 39 A, C, 40 A, C, 42 C, F

coxal spur (Thompson 1972)

Leg

see anterocoxal spina

cranium

Head

The sclerotized cuticle of the head, indicated in one figure only (Snodgrass 1947).

Fig. 10 A

crescent-shaped (Thompson 1999)

General

see lunulate

crossvein

Wing

A short vein connecting major longitudinal veins, referenced with lowercase letters of the main veins it connects separated by an hyphen (exception: crossvein h), e.g., crossvein dm-m and crossvein m-cu (Thompson 1999).

Figs 3B, 34 A, 35, 36 , 37 A, C, D

crossvein bm-cu; basal medial-cubital crossvein (McAlpine 1981)

Wing

see crossvein m-cu

crossvein bm-cu; basal medial-cubital crossvein both in part (McAlpine 1981)

Wing

see M₄ base

crossvein c-r₁

Wing

Additional crossveins between vein C and vein R₁, as seen in Lycastris (Saigusa 2006; Wootton & Ennos 1989).

Figs 3B, 35D

crossvein dm-cu; discal medial-cubital crossvein (McAlpine 1981)

Wing

see crossvein dm-m

crossvein dm-m

Wing

Apical crossvein between M₄ and M. In the old system crossvein dm-cu (McAlpine 1987; Saigusa 2006; Wootton & Ennos 1989).

Figs 34 A, 35, 36 , 37 C, D

crossvein h

Wing

Short crossvein between veins C and Sc; humeral crossvein (McAlpine 1981; Cumming & Wood 2017).

Figs 34 A, 35, 36 A–C

crossvein m-cu

Wing

Crossvein between veins CuA and M₄; medial-cubital crossvein, bm-cu (McAlpine 1981; Saigusa 2006; Wootton & Ennos 1989).

Figs 34 A, 36 A, 37 C

crossvein r-m

Wing

Crossvein between veins R₄₊₅ and anterior branch of M; radial-medial crossvein (McAlpine 1981; Saigusa 2006; Wootton & Ennos 1989).

Figs 34 A, 35A, D

crossvein r_1-r₂₊₃

Wing

Crossvein on apical part of vein R₂₊₃ to vein R₁, found in some Oriental Sphegina (Asiosphegina) species, not always entirely reaching vein R₁ (Hippa et al. 2015).

Fig. 35B

crossvein r₄₊₅-m₁

Wing

vein dividing cell r₄₊₅ in two parts, running from vein R₄₊₅ to vein M₁, found in the genus Lyneborgimyia (Doczkal & Pape 2009).

Fig. 37 A

crossvein sc-r

Wing

Crossvein between veins Sc and R₁; subcostal-radial crossvein (McAlpine 1981; Cumming & Wood 2017); stigmal crossvein (Reemer & Ståhls 2013a).

Figs 35A, C, 36 C

ctenidial lobe (Hippa & Ståhls 2005)

Male terminalia

see postgonite

ctenidion, especially on the postgonite (Hippa & Ståhls 2005)

General

see ctenidium

ctenidium (pl. ctenidia)

General

Closely set row of short spinae, comb-shaped; might be applied to a specific structure in some male genitalia (Thompson 1999; Hippa & Ståhls 2005).

Figs 54 B, D, 56 C, 58 A

dens (pl. dentis, adj. dentate)

General

A pointed, short, non-articulating extension of the exoskeleton, as long as, or shorter than, broad (Thompson 1999).

Figs 4 , 24 A, 44 B

dentate carina (Hippa 1978a)

Leg

see setulate carina

dichoptic

Head

Eyes do not meet each other dorsally between antennal base and vertex; condition seen in all females and some males (Cumming & Wood 2017).

Figs 6 D, 10 A

discal cell; cell d (Speight 2020)

Wing

see cell dm

discal sclerite

Proboscis.

Sclerotized strengthening on the labellum, together with the epifurca, furca and paraphysis (Schiemenz 1957).

Fig. 22

disticoxa

Leg

Apical/ventral part of the eucoxa of the mesoleg (McAlpine 1981).

Fig. 42 F

distiphallus

Male terminalia

Apical part of two-segmented phallus (Cumming & Wood 2017).

Figs 55 C, D

dorsal (adv. dorsally)

General

On the upper side of a structure; opposite to ventral (Thompson 1999).

Figs 1 C, D, 2 , 54 A, B

dorsal occiput

Head

Most dorsal part of the occiput directly posterior to the ocellar triangle (in part Thompson 1999), often of different texture and chaetotaxy than rest of occiput, see further under occiput.

Figs 6 A, B, 7B, 9 D, 15C, 16A

dorsomedial anepimeron

Thorax

Dorso-medial part of the plate ventral to the wing base, pilose in Eristalinus (Thompson 1999).

Fig. 29B

dorsoventral bulge (Doczkal & Pape 2009)

Head

see postcranial tubercle

dull

General

Bodyparts or markings that are not shiny, often covered in microtrichia. Although dull has a wider definition than matt(e), dull is the preferred term (Merriam et al. 2022).

Fig. 3D

ejaculatory apodeme

Male terminalia

Unpaired sclerotized structure of the sperm pump; not articulated to other sclerites of the genitalia; its shape varies among groups (Cumming & Wood 2017).

Figs 54 C, 55 C, D, 56 D–F

ejaculatory duct

Male terminalia

Tube connecting the vasa deferentia to the sperm pump; not to be confused with the old term 'ejaculatory duct' used in Microdontinae, see phallus (Cumming & Wood 2017).

n/a

ejaculatory hood (Metcalf 1921)

Male terminalia

see phallus

ejaculatory process

Male terminalia

Apically placed processes of the phallus “ejaculatory sac” in Microdontinae (Reemer & Ståhls 2013a) and possibly also homologous in Cerioidini (van Steenis et al. 2016).

Figs 56 B, F

elongated anterior tentorial pit (authors)

Head

see facial sulcus

emarginate (Vockeroth 1969).

General

see premarginal sulcus

emargination on posterior eye margin

Head

Angulation of the posterior eye margin, seen from lateral view of the head, in genera like Phytomia and Toxomerus (Thompson 1999; Ssymank et al. 2021).

Fig. 14D

empodium

Leg

Long, seta-like, median process of the arolium (McAlpine 1981).

Figs 42 A, E

endophallus

Male terminalia

Internal seminal duct of the phallus that extends basally into the sperm sac; only visible in some Microdontinae (Cumming & Wood 2017).

n/a

epandrial arm

Male terminalia

Lateral extremities of the apical cleft of the epandrium (Claussen 1991); in several Pipizella species distinctly differentiated; rarely the epandrial arms fuse together, fully enclosing the cerci apically e.g. Victoriana parvicornis.

Fig. 58 B

epandrial rim

Male terminalia

A border on the apical part of the epandrium in Pipizella and Ceriana (van Steenis & Lucas 2011; van Steenis et al. 2016).

Fig. 58 C