A new fossil species of the genus Bibio, with an update on bibionid flies from Baltic and Rovno amber (Diptera, Bibionidae)

Abstract

Species of Bibionidae from Baltic amber are reevaluated based on newly discovered material, and a key to the species is given. Bibio succineus sp. nov. is described based on one male specimen, this is the first Bibio named from Baltic amber. The males of Hesperinus electrus Skartveit, 2009 and Penthetria montanaregis Skartveit, 2009 are redescribed. A single, autoclave treated specimen of Penthetria sp. is described but not formally named. Plecia tenuicornis Skartveit, 2009 is found to be a synonym of Plecia hoffeinsorum Skartveit, 2009, this species is recorded for the first time from Rovno amber, and both sexes of the species redescribed. Additional specimens of Plecia clavifemur Skartveit, 2009 and Dilophus crassicornis Skartveit, 2009 are described. Two female specimens probably belonging to the species discussed as Dilophus sp. by Skartveit (2009) are described, but not formally named.

Full text

A new fossil species of the genus Bibio, with an update on bibionid ies
from Baltic and Rovno amber (Diptera, Bibionidae)
John Skartveit1
1 NLA University College Bergen, P.O. Box 74 Sandviken, N-5812 Bergen, Norway
http://zoobank.org/2AD03B67-2D3B-4B03-A373-59854A506F3E
Corresponding author: John Skartveit (John.Skartveit@NLA.no)
Academic editor: S. Wedmann ♦
Received
10 November 2020 ♦
Accepted
14 January 2021 ♦
Published
27 January 2021
Abstract
Species of Bibionidae from Baltic amber are reevaluated based on newly discovered material, and a key to the species is given. Bibio
succineus sp. nov. is described based on one male specimen, this is the rst Bibio named from Baltic amber. The males of Hesperinus
electrus Skartveit, 2009 and Penthetria montanaregis Skartveit, 2009 are redescribed. A single, autoclave treated specimen of Pen-
thetria sp. is described but not formally named. Plecia tenuicornis Skartveit, 2009 is found to be a synonym of Plecia hoeinsorum
Skartveit, 2009, this species is recorded for the rst time from Rovno amber, and both sexes of the species redescribed. Additional
specimens of Plecia clavifemur Skartveit, 2009 and Dilophus crassicornis Skartveit, 2009 are described. Two female specimens
probably belonging to the species discussed as Dilophus sp. by Skartveit (2009) are described, but not formally named.
Key Words
Dilophus, Hesperinus, Penthetria, Plecia, Eocene
Introduction
Bibionid ies are a very abundant group in European Ter-
tiary insect fossil deposits (e.g., Skartveit and Nel 2017),
where they frequently make up a large percentage of the
total insect specimens. On the other hand, bibionid spec-
imens are relatively scarce among amber fossils, though
a number of species have been described from European
amber fossils (Gee et al. 2001; Skartveit 2009). Outside
Europe, bibionid ies are known from Cretaceous Cana-
dian (Peterson 1975), Miocene Dominican (Waller et al.
2000; Skartveit and Bechly 2013) and Chiapas (Hardy
1971) amber.
Rovno amber comes from mines in Rivne Oblast,
Ukraine (Perkovsky et al. 2010). The deposits have
been dated to the Lower Oligocene, suggesting a
younger age than Baltic amber (Perkovsky et al. 2010),
though more recently it has been redated to the late Eo-
cene (Perkovsky and Makarkin 2019). While the fauna
in Rovno amber is rather similar to the one in Baltic
amber, suggesting they are of the same age and origin
(e.g., Dlussky and Rasnitsyn 2009; Szwedo and Sontag
2013), some dierences have been noted between the
two palaeofaunas (Perkovsky et al. 2007), with about
100 taxa found in Rovno amber not recorded from Bal-
tic amber (Perkovsky et al. 2010). Rovno and Baltic
amber are very similar in chemical composition; how-
ever, analyses of stable carbon and hydrogen isotopes
in Rovno, Bitterfeld and Baltic amber suggest that Rov-
no amber is of similar age to Baltic amber, but origi-
nated in a more southerly location (Mänd et al. 2018).
Bibionid ies have not previously been recorded from
Rovno amber.
I (Skartveit 2009) reviewed a reasonably large mate-
rial of bibionids from Baltic amber. Subsequently, some
additional specimens have surfaced which can shed some
light on the Baltic amber bibionid fauna; they are de-
scribed here.
Dtsch. Entomol. Z. 68 (1) 2021, 81–99 | DOI 10.3897/dez.68.60611
Copyright John Skartveit. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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John Skartveit: Baltic and Rovno amber Bibionidae82
Methods
The present paper is based on 16 specimens of Bibionidae
in Baltic amber. The specimens were in cut and polished
pieces of amber acquired through commercial dealers, un-
fortunately without any information on where they were
collected except that they were from Baltic (or Rovno) am-
ber. The dealers provided digital images of the specimens, I
carried out further studies of the specimens under stereo mi-
croscopes (Olympus SZ61, WildM3Z), photographs were
taken with digital cameras (Nikon 4500, Olympus E3), I
collected measurements using measuring oculars. I made
line drawings based on digital images of the specimens.
Wing vein nomenclature mainly follows Merz and
Haenni (2000), with the modication that the section of
R between crossvein R-M and R2+3 is referred to as R2-5.
The segment of M basal to R-M is referred to as “basal
M”, the segment between R-M and furcation as “distal
M”. The naming of the veins is shown in Fig. 12.
Repositories, Institutional acronyms or
Institutional abbreviations
CCHH Collection of Christel and Hans-Werner Hof-
feins, Hamburg, Germany, to be deposited in
SDEI.
JS Author’s collection, to be deposited in SDEI.
MHNN Museum d’histoire naturelle, Neuchâtel, Swit-
zerland.
SDEI Senckenberg Deutsches Entomologisches In-
stitut, Müncheberg, Germany.
Results
Key to the species of Bibionidae known from Baltic amber
Plecia borussica Meunier, 1907 is not included since I have not been able to locate any material of it, and Plecia sp.
3 of Skartveit (2009) is not included since the antennae were impossible to see in the specimen at hand. The former
species should be recognisable by the gonostyli being obviously expanded apically, the latter by the epandrium having
a sharp spine in the middle.
1 Legs slender, femorae and tibiae not thickened .......................................................................................................... 2
– Legs thickened, at least fore femorae clearly expanded (Bibioninae) ......................................................................... 12
2 Antenna longer than head (Fig. 13). (genus Hesperinus) ............................................................................................. 3
– Antenna shorter than head (Figs 16, 21, 22).............................................................................................................. 5
3 Antennal flagellum 10-segmented. Wing hyaline with unpigmented veins and invisible pterostigma (female only
known) ...............................................................................................................Hesperinus hyalopterus Skartveit, 2009
– Antennal flagellum 7–8-segmented. Wing with veins brownish, pterostigma more or less visible (males only known) ....4
4 Head strongly dichoptic, complex eyes widely separated dorsomedially. Gonostylus curved and sharply pointed
(Fig. 1) ....................................................................................................................Hesperinus electrus Skartveit, 2009
– Head weakly dichoptic, complex eyes nearly meeting dorsomedially. Gonostylus nearly straight and blunt ....................
.......................................................................................................................Hesperinus macroculatus Skartveit, 2009
5 Vein R2-5 unforked, no vein R2+3 (possibly a teratology, but known from two specimens) .................................................
......................................................................................................................... Penthetria integroneura Skar tveit, 2009
– Vein R2-5 forked, with a clear vein R2+3 (Figs 15, 18–20) ............................................................................................... 6
6 Wing with R2+3 straight, forming a sharp angle with R4+5 (Figs 15, 18). Male terminalia with strong, blunt gonostyli and
bilobate epandrium (Fig. 17) ..................................................................................................................................... 7
– Wing with R2+3 more or less curved, forming a less sharp angle with R4+5 (Figs 19, 20). Male terminalia not so, epandrium
not clearly bilobate. (genus Plecia) ............................................................................................................................ 8
7 Vein R2+3 originates near base of Rs, so that the segment R2-5 is not much more than half as long as R4+5 (Figs 2, 15) ....
.........................................................................................................................Penthetria montanaregis Skar tveit, 2009
– Vein R2+3 originates near middle of Rs, so that the segment R2-5 is nearly as long as R4+5 (Figs 3, 18) ........ Penthetria s p.
8 Wing with R4+5 kinked at junction with R2+3, which is short and almost vertical (Fig. 4) ....Plecia clavifemur Skartveit, 2009
– Wing with R4+5 not kinked at junction with R2+3, which is longer and less steep (Figs 19, 20) ....................................... 9
9 Antenna with flagellum 8-segmented (Figs 21, 22) ................................................................................................... 10
– Antenna with flagellum 9-segmented ....................................................................................................................... 11
10 Wing with strong microtrichia, pterostigma dorsally densely pilose. Male: gonostylus straight, long and slender (Fig. 23).
Female eye small, not strongly protruding (Fig. 22) (Figs 5–7) .................................. Plecia hoffeinsorum Skartveit, 2009
– Wing with fine microtrichia, pterostigma not conspicuously pilose. Male unknown. Female eye large and protruding .....
.......................................................................................................................................... Plecia prisca Meunier, 1899
11 Larger, mesonotum length about 1.6 mm. Female only known ....................................Plecia brunniptera Skartveit, 2009
– Smaller, mesonotum length about 0.8 mm. Male only known .............................................. Plecia sp. 1 Skar tveit, 2009

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12 Thorax without spines on pronotum and mesonotum (Fig. 25). Anterior tibia without mesal spines and apical spine
circlet (Fig. 26) ....................................................................................................................................................... 13
– Thorax with transverse rows of spines on pronotum and mesonotum (Fig. 29). Anterior tibia with mesal spines and
apical spine circlet (Fig. 30) (genus Dilophus) .......................................................................................................... 15
13 Rs does not extend to M, with a short but distinctive crossvein R-M. (Figs 8, 24) ........................Bibio succineus sp. nov.
– Rs extends to M and merges with it for a short distance (genus Bibiodes) ................................................................. 14
14 Larger species, body length 4–4.5 mm. Male hind first tarsomere swollen. Male gonostylus bilobate ............................
...................................................................................................................................Bibiodes balticus Skartveit, 2009
– Very small species, body length 2.5–3 mm. Male hind first tarsomere not swollen. Male gonostylus simple digitiform ....
...................................................................................................................................... Bibiodes nanus Skartveit, 2009
15 Antenna short and stout, flagellum 6–7-segmented (Fig. 29). Protibial mesal spines long and erect (Fig. 30) (Fig. 9) ....
.............................................................................................................................Dilophus crassicornis Skartveit, 2009
– Antenna longer, more slender, flagellum with at least 9 segments (Fig. 33). Protibial mesal spines not long and erect
(Fig. 34) .................................................................................................................................................................. 16
16 Antennal flagellum 9–10-segmented, not very slender (Fig. 33). Fore tibia with 2+2 mesal spines (Fig. 34)
(Figs 10, 11) ..............................................................................................................................................Dilophus sp.
– Antennal flagellum 12-segmented, slender. Fore tibial spines otherwise .................................................................... 17
17 Fore tibia with 2+3 strong, mesal spines. Antenna longer, nearly as long as head ..... Dilophus succineus Skartveit, 2009
– Fore tibia with 1+2 rather small, mesal spines. Antenna shorter, considerably shorter than head ..................................
.......................................................................................................................... Dilophus palaeofebrilis Skartveit, 2009
Taxonomy
Hesperinus electrus Skartveit, 2009: 5–7
Figs 1, 12–14
Note. The species was described based on a single, male
specimen (Skartveit 2009). One additional male speci-
men has turned up which shows details in wing venation
and terminalia better than the type.
Holotype (male) SDEI Dip-00832 – CCHH #1093-1.
Additional material (male) CCHH # 1789-1
Updated description of the species including type
specimen (some measurements from the holotype cor-
rected): Total length 4.35–4.40 mm (N = 2). Colour dark
brownish, body semi-matt, covered with short, coarse,
dark hairs.
Figure 1. Hesperinus electrus, male. CCHH # 1789.1. Photo: Christel and Hans-Werner Hoeins.

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John Skartveit: Baltic and Rovno amber Bibionidae84
Head (Fig. 13): Length 0.47–0.52 mm (N = 2). Clearly
dichoptic, complex eyes separated in frons by about the
width of ocellar tubercle. Ocellar tubercle medium-sized,
fairly prominent. Complex eye somewhat reniform, con-
cave posteriorly, without apparent intraocular setae. Oc-
ciput with rather dense, short, dark pile. Antenna slen-
der, about one and a half times as long as head, agellum
0.78 mm long, 0.06 mm wide (N = 2), eight-segmented,
all agellomeres clearly longer than wide, with dark setae
about as long as the width of the agellomeres. Pedicel
conical, pedicel and rst agellomere wider than the rest
of agellum. Palp brown, relatively long, last segment
cylindrical. Mouthparts, apart from palp, not conspicu-
ously developed.
Thorax: Length 0.90–0.92 mm (N = 2), width 0.55 mm
(N = 1). Reddish brown with darker vittae around no-
taulix and anterolaterally at humerus, semi-matt, grayish
pruinose, with sparse, short setae. Mesonotum with deep
sulci. Pleura bare, densely grayish pruinose except for
glabrous patches posteriorly on katepisternum and epi-
meron. Haltere brown.
Wing (Fig. 12) Length 4.18–4.35 mm (N = 2), width
1.32–1.52 mm (N = 2), length/width = 2.75–3.30 (wing
of holotype may be slightly folded). Very slightly brown-
ish fumose, membrane with very ne microtrichia, veins
ne and brown throughout. Pterostigma not apparent.
Costa with ne setulae about as long as width of vein,
extends to nearly half-way between apices of R4+5 and M1.
Humeral vein short and oblique. R2+3 rather long, oblique,
basally bent. R4+5 strongly curved. R-M nearly vertical.
M-veins apically very ne, hardly visible at wing edge, a
Figure 2. Penthetria montanaregis, male. JS-Baltic-001. Photo:
Marius Veta.
Figure 3. Penthetria sp., female. SDEI Dip-00823 – CCHH#1789-4. Photo: Christel and Hans-Werner Hoeins.

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Figure 4. Plecia clavifemur, female. JS-Baltic-003. Photo: Jonas Damzen.
Figure 5. Plecia hoeinsorum, male. JS-Baltic-004. Photo:
Marius Veta.
Figure 6. Plecia hoeinsorum, female. JS-Baltic-006. Photo:
Marius Veta.

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John Skartveit: Baltic and Rovno amber Bibionidae86
Figure 8. Bibio succineus sp. nov., holotype, male. JS-Baltic-009. Photo: Marius Veta.
Figure 7. Plecia hoeinsorum, male, Rovno amber. JS-Baltic-008. Photo: Jonas Damzen.

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Figure 9. Dilophus crassicornis, female. CCHH # 1789-2. Photo: Christel and Hans-Werner Hoeins.
Figure 10. Dilophus sp., female. JS-Baltic-010. Photo: John Skartveit.

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John Skartveit: Baltic and Rovno amber Bibionidae88
Figure 11. Dilophus sp., female. JS-Baltic-011. Photo: Jonas Damzen.
Figure 12. Hesperinus electrus, male, wing. Scale bar: 1 mm.
little curved basad. CuA1 straight, CuA2 apically strong-
ly curved basad. CuP ne, gently curved, reaches wing
edge. Length of wing veins in mm (N = 2) subcosta 2.2–
2.3, basal R 1.0–1.3, distal R1 1.5–1.6, Rs 0.45–0.55, R2–5
0.62–0.65, R2+3 0.75–0.91, R4+5 1.6–1.8, R-M 0.14, bas-
al M 1.4, distal M 0.30–0.38, M1 1.8, M2 1.5–1.6, M-Cu
0.10–0.15, CuA 1.0–1.4, CuA1 1.7–2.0, CuA2 1.3–1.6.
Legs: Dark brown, long and slender, clad with strong,
short, dark pile. Fore tibia with one, mid- and hind-tibiae
with two short, straight, dark spurs. Tarsi very slender.
Leg measurements (N = 2 unless otherwise stated) fore
femur 1.4–1.5 mm long, fore tibia 1.4 mm long (N = 1),
fore rst tarsomere 0.77 mm long (N = 1), mid femur
1.5 mm long (N = 1), mid tibia 1.3 mm long (N = 1),
hind femur 1.6–1.9 mm long, 0.12 mm wide (N = 1), hind
tibia 1.8–2.1 mm long, 0.09 mm wide (N = 1), hind rst
tarsomere 0.86 mm long (N = 1).
Abdomen: Dark brown, cylindrical, slender, rather
densely clad with dark brown pile. Length 3.1 mm, width
0.5 mm (N = 1).
Terminalia (Fig. 14): Width of hypopygium 0.47 mm
(N = 1). Hypopygium slightly expanding apicad, clad
with short, dark pile. Gonostylus curved and sharp-
ly pointed, 0.24 mm long (N = 1). Posterior edge of
gonocoxosternite almost straight. Epandrium apparently
quite small, not possible to see clearly, probably round-
ed-rectangular. Ejaculatory apodeme large and promi-
nent, apically dome-shaped.

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Discussion. The original description was found to con-
tain some errors, e.g., the agellum has eight, not seven
segments, and is shorter than stated in the description. The
poorly developed mouthparts suggest that this species did
not feed in the adult stage, this may be a general trait for
Hesperinus species as all seem to have very small mouth-
parts. The genus Hesperinus has frequently been referred
to a separate family, the Hesperinidae (e.g., Krivosheina
1997). However, molecular evidence suggests that the ge-
nus belongs in the Bibionidae (Ševčik et al. 2016) and this
is also supported by fossil material, where Hesperinus
and Penthetria species look far more similar than in the
modern species. Hence, I prefer to place Hesperinus and
Penthetria together in the subfamily Hesperininae in
Bibionidae (Skartveit and Ansorge 2020).
Penthetria montanaregis Skartveit, 2009: 13
Figs 2, 15–17
Note. The species was described based on a single, male
specimen (Skartveit 2009), however this specimen was to
a large extent covered by white emulsion (Verlumung).
The present specimen claries some aspects of the spe-
cies’ morphology.
Holotype, male, MHNN 972. Additional material,
male, JS-Baltic-001, in piece of amber 39×32×3 mm.
Redescription of the species. Male: Total length 6.3–
7.9 mm (N = 2). Colour uniormly dark, probably brown-
ish-black in life.
Head (Fig. 16): Length 0.75 mm, width 1.05 mm
(N = 1). Only just holoptic, complex eyes in contact only
2–3 ommatidia, meeting at distance similar to diameter of
ocellar tubercle anterior to tubercle. Complex eye nearly
bare, with very short, ne and sparse intraocular hairs.
Ocellar tubercle small but fairly prominent, with few
strong, short, dark brown setae on posterior face. Ros-
trum not protruding. Palp not possible to see in this spec-
imen. Antenna: agellum slightly conical, 8-segmented,
0.58 mm long, 0.09 mm wide, segments subquadrate
when seen laterally.
Thorax: Length 1.35–1.84 mm (N = 2), width 1.16 mm
(N = 1, smaller specimen). Dorsal side covered by Verlu-
mung, surface structure not possible to see. With irreg-
ularly biseriate, short and ne, dark dorsocentral setae,
notum otherwise practically bare. Haltere brown.
Wing (Fig. 15): Length approximately 5.6 mm, width
2.0 mm, length/width = 2.8 (N = 1). The wing is some-
what crumbled, exact vein measurements dicult to nd.
Brown fumose, costal cell mostly darkened, but unpig-
mented basally of humeral crossvein. Pterostigma and
veins dark brown, distinctive but not particularly strong.
Costa with ne setulae, veins otherwise bare. Costa ex-
tends a little beyond apex of R4+5. Humeral crossvein
rather strong, vertical. Subcosta distinctive, relatively
strong, but merges with R at humeral crossvein, not visi-
ble basally. R2+3 ne, straight, oblique, about 0.4× length
of R4+5. R4+5 moderately curved. R-M vertical. M basally
not connected to R nor to CuA. Fork of M rather narrow.
M-CuA pigmented only in posterior half (nearest CuA1).
CuA1 rather straight, CuA2 bent caudad in apical fourth.
CuP not prominent. Vein lengths, all in mm: Basal R 2.25,
Rs 0.86, R2-5 0.36, R2+3 0.68, R4+5 1.58, R-M 0.17, basal M
2.25, distal M 0.45, M1 2.06, M2 1.61, M-CuA 0.15, CuA
1.54, CuA1 2.44, CuA2 1.73.
Legs: Dark brown, densely clad with strong, short,
dark setae. Femorae moderately clavate, all tibiae and
tarsi slender. Tibial spurs dark, straight and sharp.
Abdomen: Length 4.1 mm, width 0.9 mm (N = 1),
slightly conical. Tergites shiny, brownish-black, with ne
and rather short, dark brownish pile.
Terminalia (Fig. 17): Width of hypopygium 0.71 mm
(N = 1). Epandrium bilobate, lobes rounded with dense,
rather long, dark brown setae. Gonocoxite with robust,
Figure 13. Hesperinus electrus¸male, head. Scale bar: 0.1 mm.
Figure 14. Hesperinus electrus, male, terminalia. Scale bar:
0.1 mm.

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John Skartveit: Baltic and Rovno amber Bibionidae90
dark brown setae, Gonostylus length 0.39 mm, rather
long, straight, apically a little expanded, on posterior mar-
gin with about 8 strong, dark brown setae. (note: the ap-
parent shape of the gonostylus is rather dierent from the
holotype of Penthetria montanaregis, but this is probably
due to preservation in dierent angles. The apparent shape
of the gonostylus in male Bibionidae is extremely depen-
dent on perspective). Ejaculatory apodeme rather wide.
Penthetria sp.
Figs 3, 18
Material. Female, SDEI Dip-00823 – CCHH#1789-4,
embedded in a clear amber block which has undergone
autoclave treatment (C. Hoeins, in litt.).
The species diers from Penthetria montanaregis in
the following aspects: smaller, wing length about 4.5 mm,
wing narrower, more than 3 times as long as wide (in bibi-
onids, females generally have wider wings than conspe-
cic males) with reduced anal lobe, R2+3 placed more dis-
tally so that the segment R2-5 is almost as long as R4+5 (less
than half as long in P. montanaregis), fork of M strongly
asymmetrical (nearly symmetrical in P.montanaregis),
CuA2 apically strongly curved basad (moderately curved
basad in P. montanaregis). It diers from female Pen-
thetria integroneura Skartveit, 2009 most conspicuously
by the presence of R2+3 and by the more strongly curved
CuA-veins, also by the presence of strong setae dorsally
on the thorax and apparently by the head shape, though
the latter is likely aected by autoclave treatment.
Description. Male unknown.
Female (N = 1): Total length 5.0 mm. The specimen is
of a uniform, dark colour, likely aected by the autoclaving.
Head: length 0.58 mm. Apparent shape probably af-
fected by autoclaving, outline of complex eye not pos-
sible to see. Flagellum 0.42 mm long, 0.07 mm wide,
7-segmented, shape of agellomeres obviously aect-
ed by autoclaving. Palp relatively long, outer segments
appear to be very slender, but this is likely an artefact
caused by autoclaving.
Thorax: Length 1.18 mm. Dorsally with some relative-
ly long and strong, erect setae, details otherwise not pos-
sible to make out. Haltere light brown.
Figure 15. Penthetria montanaregis, male, wing. Scale bar: 1 mm.
Figure 16. Penthetria montanaregis, male, head and thorax.
Scale bar: 1 mm.
Figure 17. Penthetria montanaregis, male, terminalia. Scale
bar: 0.1 mm.

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Legs: relatively long, femorae slightly clavate, tibiae
apparently very slender (possibly aected by autoclav-
ing). The legs are clad with relatively long, brown pile, on
tibiae about as long as the tibia’s width. Tibial spurs ne
and sharp. Segment measurements, all inn mm: fore fe-
mur length 1.37, width 0.16, fore tibia length 1.32, width
0.12, mid femur length 1.23, hind femur length 1.69,
width 0.18, hind tibia length 1.71, width 0.13, hind rst
tarsomere length 0.63, width 0.07.
Wing (Fig. 18): Length 4.6 mm, width 1.5 mm,
length/width = 3.1. Brown fumose, relatively slender,
veins brown throughout, R-veins considerably more
robust than M- and CuA-veins. Costa relatively strong
with rather long setules which at least basally are longer
than the width of the vein, extending a little past half-
way between apices of R4+5 and M1. Humeral vein pres-
ent, oblique. Pterostigma relatively small, oval, brown.
Subcosta ne but distinctive, straight. R2+3 oblique, al-
most straight, a little less than half as long as R4+5, which
is gently curved. Rs straight, nearly three times as long
as R-M, which is vertical. R2-5 (basally of R2+3) almost
as long as R4+5 (distally of R2+3). M basally connected to
CuA. M-veins ne, M and M2 form an approximately
straight line with M1 diverging forward from this. CuA1
apically slightly, CuA2 strongly bent basad. CuP paral-
lel to CuA/CuA2, ne but does reach wing margin. Anal
lobe strongly reduced, basal-posterior edge of the wing
nearly straight-lined. Vein lengths, all in mm: Subcos-
ta 2.48, Basal R 1.46, R1 1.44, Rs 0.53, R2-5 1.09, R2+3
0.58, R4+5 1.27, R-M 0.19, basal M 1.41, distal M 0.44,
M1 1.85, M2 1.41, M-CuA 0.14, CuA 1.02, CuA1 1.99,
CuA2 1.18. The wings have numerous, transverse cracks
probably caused by autoclaving, this has not altered the
overall shape, though.
Abdomen: Length 3.6 mm, dark, cylindrical, with ne,
dark, short pile. Shape of terminalia dicult to make out,
probably aected by autoclaving.
Discussion. The specimen of this species is obvious-
ly aected by autoclave treatment, particularly so in the
head where the overall shape appears changed, the out-
lines of the complex eyes are not possible to make out,
and the shapes of the antennal and palp segments are
strongly disrupted. The autoclaving appears also to have
altered the appearance of the terminalia, and possibly tho-
rax and legs to some extent. However, the wing charac-
ters appear to be uncompromised and should be sucient
to recognise the species, at the very least to dierentiate
it from the other species of Penthetria known from Bal-
tic amber. Identifying Penthetria species based on female
specimens is very dicult in recent species and this is
probably so in fossil species, too, hence this specimen is
not given a formal name at this stage.
Plecia clavifemur Skartveit, 2009: 15–16
Fig. 4
Type material, females. Holotype, SDEI Dip-00830
– CCHH#1474.2. Paratypes SDEI Dip-00845 –
CCHH#1505.1; SDEI Dip-00846 – CCHH#1501.5.
Additional material, females. JS-Baltic-002, in piece
of amber 20×15×4 mm, JS-Baltic-003, in piece of amber
18×13×6 mm. These specimens do not reveal any charac-
ters not seen in the type material, but their morphometric
data is given below.
Total length 3.47–4.62 mm.
Head: Length 0.42 mm (N = 1), width 0.57–0.60 mm.
Flagellum length 0.40–0.47 mm, width 0.08 mm (N = 2).
Thorax: Length 0.83–0.92 mm.
Legs: Fore femur 0.66–0.79 mm long, 0.12–0.15 mm
wide, fore tibia 0.75–1.11 mm long, 0.08–0.09 mm wide,
fore rst tarsomere 0.24–0.38 mm long, 0.05–0.07 mm
wide, fore second to fth tarsomeres 0.19, 0.13, 0.11 and
0.15 mm long (N = 1). Mid femur 0.88 mm long, 0.15 mm
wide (N = 1), mid tibia 0.69 mm long, 0.08 mm wide (N
= 1). Hind femur 0.90–1.24 mm long, 0.11–0.15 mm wide,
hind tibia 0.97–1.20 mm long, 0.08–0.12 mm wide, hind
rst tarsomere 0.23–0.41 mm long, 0.07–0.09 mm wide.
Wing: length 3.05–3.11 mm, width 1.00–1.39 mm,
length/width = 2.24–3.05. Vein lengths, all in mm: Sub-
costa 1.50–1.58, basal R 1.00–1.13, distal R1 0.75–0.85,
Rs 0.27–0.38, R2-5 0.58–0.83, R2+3 0.16–0.23, R4+5 0.64–
0.68, R-M 0.07–0.17, basal M 0.92–1.05, distal M 0.33–
0.34, M1 1.20–1.37, M2 0.88–1.00, M-CuA 0.11 (N = 1),
CuA 0.67–0.79, CuA1 1.12–1.54, CuA2 0.58–1.16.
Abdomen: Length 2.5 mm (N = 1).
Discussion. The two specimens examined are similar
in the shape of the head and antenna, general aspects of
Figure 18. Penthetria sp., female, wing. Scale bar: 1 mm.

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John Skartveit: Baltic and Rovno amber Bibionidae92
wing venation (short R2+3, kinked R4+5, CuA2 bent sharply
basad) and terminalia, however they are rather dierent
with respect to some morphometric traits, particularly
length of leg segments and the general shape of the wing.
At the present state of knowledge I interpret this dier-
ence as within intraspecic variation, though additional
material, particularly if male specimens are found, may
reveal that there are more than one species involved.
Plecia hoeinsorum Skartveit, 2009: 17–19
Figs 5–7, 19–23
Plecia tenuicornis Skartveit, 2009: 20–22. Syn.n.
Type material. Holotype (male) of Plecia hoeinsorum
SDEI Dip-00827 – CCHH#1448-2, preserved together
with six conspecic males. Paratype (male) SDEI Dip-
00843 – CCHH#1629-2. Holotype (male) of Plecia te-
nuicornis SDEI Dip-00828 – CCHH#1501-2. Paratypes
(males): SDEI Dip-00837 – CCHH#335-2. SDEI Dip-
00838 – CCHH#935-2. SDEI Dip-00839 – CCHH#1025-
1. SDEI Dip-00840 – CCHH#1025-2. SDEI Dip-00841
– CCHH#1567-3. SDEI Dip-00843 – CCHH#1629-2
(Preserved together with holotype). Previously studied
non-type, female, CCHH#1501-3.
New material, Baltic amber: males: JS-Baltic-004,
in piece of amber 27×20×6 mm, syninclusions: cecido-
myiid midge, 2 phorid ies; JS-Baltic-005, in piece of
amber 16×12×4 mm. JS-Baltic-007, in piece of amber
22×13×6 mm. Females: SDEI In 001701 (syninclusion
with Sciarid midge); JS-Baltic-006, in piece of amber
13×7×3 mm. Rovno amber, male: JS-Baltic-008, in rather
large piece of amber 36×20×15 mm, syninclusions: copi-
ous plant debris, possibly ower fragments.
The species was described based on seven male speci-
mens preserved together in one piece of amber. The pres-
ent specimens do show the male terminalia better than the
type material, hence this is redecribed here, otherwise the
external morphology is adequately described in the orig-
inal descriptions of Plecia hoeinsorum and Plecia te-
nuicornis (Skartveit 2009: 17–22). The female of Plecia
hoeinsorum was described from a compression fossil
from Grube Messel (Skartveit and Wedmann 2016). The
two species Plecia hoeinsorum and Plecia tenuicornis
were originally thought to have rather dierent male termi-
nalia (Skartveit 2009, gs 34, 35, 46, 47), however study-
ing additional specimens suggests that the two “forms” are
actually the same structure with the gonostylus xed in
dierent positions. As usual with Bibionidae the angle of
view is quite critical when studying these structures.
Measurements, including new material. Males:
body length 4.5–5.2 mm (N = 4), thorax length 0.92–
1.30 mm (N = 8), wing length 4.0–5.2 mm (N = 6). Fe-
males: body length 4.5–4.6 mm (N = 2), thorax length
0.97–1.17 mm (N = 2), wing length 4.6 mm (N = 1).
Wings as in Figs 19, 20, head as in Figs 21, 22.
Redescription of male terminalia (Fig. 23). Hy-
popygium width 0.43 mm (N = 1), outline almost rect-
angular, slightly expanded apicad. Gonostylus 0.22 mm
Figure 19. Plecia hoeinsorum, male, wing. Scale bar: 1 mm.
Figure 20. Plecia hoeinsorum, female, wing. Scale bar: 1 mm.

Dtsch. Entomol. Z. 68 (1) 2021, 81–99
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93
long, attached apically on gonocoxite, long and slender,
straight, apically somewhat pointed, with numerous long,
curvy setae. Epandrium rather small, rounded-rectan-
gular, posterior edge sligthly convex. Gonocoxosternite
apically with a short, blunt tooth on each side just mesal
to gonostylus attachment, posterior edge slightly convex.
Bibio succineus sp. nov.
http://zoobank.org/2482E3D0-F1D5-443E-B236-BB1AEA235979
Figs 8, 24–28
Type material. Holotype (male), SDEI Dip-00900 – JS-Bal-
tic-009. The specimen is preserved in a piece of yellowish
amber, 30×17×6 mm. Syn-inclusion: one sciarid gnat.
Additional material (female) Coll. Kernegger
59/2006. The specimen was briey described by Skart-
veit (2009: 26–27).
Comparison to other species. Four species of Bibio
have been described from the Eocene/Oligocene of Isle
of Wight (Krzeminski et al. 2019). Of these, Bibio gur-
netensis Cockerell, 1917 and Bibio oblitus Cockerell,
1921 both have crossvein R-M much longer than the
basal Rs, this character suggests the species belong in
the genus Dilophus, though, not having seen the original
material, I will not make a formal transfer here. Bibio ex-
tremus Cockerell, 1921 diers from the present species in
that the basal part of Rs is quite steep and that crossvein
M-Cu meets M2 considerably distally of furcation. Bibio
oligocenus Cockerell, 1917, which despite the name was
described from the late Eocene, diers from the present
species by being larger (wing length 8 mm) with a con-
spicuously darkened costal cell in the wing.
Etymology. The epithet is derived from Latin succi-
num, amber, referring to the preservation of the type spec-
imen. It is the rst species of the genus Bibio described
from amber fossils.
Diagnosis. A medium-sized Bibio, body length about
7.5 mm. Body and legs entirely black, densely pilose,
pile on thorax and abdomen pale, black on legs. Anten-
nal agellum 8–9-segmented. Haltere pale brown. Wing
light brownish fumose in male, brown fumose in female,
pterostigma pale and indistinctive, radial sector about
four times as long as R-M. Fore tibia with spur a little
less than half as long as spine. Hind tarsus not enlarged.
Description. Male (N = 1): Total length 7.5 mm, en-
tirely black.
Head (Fig. 25): Length 1.37 mm, width not possible to
measure. Complex eye with rather dense, pale, ne, me-
dium-length intraocular pile. Ocellar tubercle not promi-
nent, with short, dark setae. Rostrum not prominent. An-
tenna: agellum 8-segmented, 0.53 mm long, 0.13 mm
wide. Two distal palp segments slender (more basal seg-
ments not possible to see).
Thorax: Length 2.2 mm, black, very shiny. Pile pale,
anteriorly rather short, getting longer in posterior part,
sides of mesonotum and pleurae with long but rather
sparse, pale pile. Sides of mesonotum with rather coarse,
Figure 21. Plecia hoeinsorum, male, head and thorax. Scale
bar: 1 mm.
Figure 22. Plecia hoeinsorum, female, head and thorax. Scale
bar: 1 mm.
Figure 23. Plecia hoeinsorum, male, terminalia. Scale bar:
0.1 mm.

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John Skartveit: Baltic and Rovno amber Bibionidae94
mesh-like microsculpture. Scutellum rounded with long,
pale, proclinate setae along edge. Meron very shiny, in
upper corner with about 20 long, pale hairs. Haltere pale
brown, not possible to see well.
Wing (Fig. 24): Length 5.6 mm, width 1.9 mm, length/
width = 2.92. Slightly brownish fumose, Costa and R1
light brown, posterior veins colourless. Pterostigma pale
brown, inconspicuous, 0.45 mm long, 0.15 mm wide.
Membrane without conspicuous microtrichia. Costa
extends to apex of R4+5. Humeral vein present, ne and
oblique. Subcosta weak, visible only in distal part. Basal
radial sector about four times as long as crossvein R-M, M
curves towards R1 at R-M. M basally clearly connected to
CuA. M-Cu oblique, meets M at furcation. CuA1 apically
moderately, CuA2 strongly curved basad. Vein lengths, all
in mm: Basal R 2.51, distal R1 1.20, Rs 0.39, R4+5 2.63,
R-M 0.09, basal M 1.80, distal M 0.94, M1 1.95, M2 1.73,
M-CuA 0.38, CuA 1.13, CuA1 2.51, CuA2 1.91.
Legs: Black, clothed with short, strong, dark setae.
Fore tibia (Fig. 26) with spur about half as long as spine.
Hind femur (Fig. 28) basally thin, expanding at about
¼ of length, outer part stocky. Hind tibia rather slender,
densely pilose, apparently without bare eld of sensil-
lae. Tarsus slender. Fore femur length 1.24 mm, width
0.32 mm, hind femur length 2.29 mm, width 0.41 mm,
hind tibia length 2.25 mm, width 0.26 mm, hind rst tar-
somere 0.63 mm long, 0.18 mm wide, hind second to fth
tarsomeres length 0.38, 0.28, 0.23, 0.37 mm.
Abdomen: Black, clothed with rather short, ne,
pale pile.
Terminalia: Gonostylus apically slender, rather
straight. Hypopygium otherwise not possible to see.
Female (tentatively associated, N = 1): Total length
7.5 mm, entirely black.
Head: Antennal agellum 9-segmented. Occiput with
short, dark setae. Complex eye rather small, rounded,
with short, scattered, brownish intraocular pile.
Thorax: Mesonotum length 1.9 mm. Covered by Ver-
lumung in the specimen available. Haltere yellowish.
Wing: Brown fumose, membrane without microtrichia.
Costa and R-veins brown, more posterior veins colourless.
Basal radial sector about ve times as long as crossvein R-M
Legs: black, rather stout. Length of fore femur 1.5 mm,
width 0.5 mm, length of fore tibia 1.4 mm, of hind tibia
2.2 mm. Fore tibia (Fig. 27) with spine about three times
Figure 24. Bibio succineus sp. nov., male, wing. Scale bar: 1 mm.
Figure 25. Bibio succineus sp. nov., male, head and thorax.
Scale bar: 1 mm.
Figure 26. Bibio succineus sp. nov., male, fore tibia. Scale
bar: 1 mm.

Dtsch. Entomol. Z. 68 (1) 2021, 81–99
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95
Figure 27. Bibio succineus sp. nov., male, hind leg. Scale
bar: 1 mm.
Figure 28. Bibio succineus sp. nov., female, fore leg. Scale
bar: 1 mm.
as long as spur, this is stout, straight and pointed. The
tibia is clothed with quite long, ne setae and has a eld
of rounded coeloconical sensillae in the middle of the an-
terior face. The tarsi are quite slender.
Abdomen: cylindrical, no details possible to see.
Terminalia: no details possible to see.
Dilophus crassicornis Skartveit, 2009: 31–34
Figs 9, 29–31
Type material. Holotype, male, MHNN 907. Paratypes:
males, SDEI Dip-00835 – CCHH#932-4; SDEI Dip-
00836 – CCHH#1629.1.
Non-type specimens previously examined. Male,
MHNN 1412, females: CCHH#932.2, CCHH#1121.
Additional material. Female, CCHH # 1789-2; fe-
male, JS-Baltic-012, in piece of amber 15×8×4 mm.
Redescription, female. Total length 3.8–5.1 mm
(N = 3).
Head (Fig. 29): Length 0.62–0.77 mm (N = 3), width
0.59–0.60 mm (N = 2), eye length 0.36–0.40 mm (N = 2),
width 0.27 mm (N = 1). Flagellum 6–7-segmented,
0.32 mm long, 0.09 mm wide.
Thorax: Length 1.22–1.55 mm (N = 3), width 0.65 mm
(N = 1, smallest specimen). Haltere light brown.
Wing: Length 3.44–3.75 mm (N = 2). Hyaline, slight-
ly brownish, veins ne and brown. Pterostigma brown.
Costa extends to half-way between apices of R4+5 and M1.
Legs: Brown, sparingly clad with ne, short, brown
pile. Fore tibia (Fig. 30) slightly sinuate, mesally with
three long, erect, sharp spines, apically with spine circlet
Figure 29. Dilophus crassicornis, female, head and thorax.
Scale bar: 1 mm.

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John Skartveit: Baltic and Rovno amber Bibionidae96
Figure 30. Dilophus crassicornis, female, fore tibia. Scale
bar: 0.1 mm. Figure 31. Dilophus crassicornis¸female, terminalia, lateral view.
of six long, diverging spines. Mid- and hind tibia apically
with circlet of six spinose, brown setae. All tarsi slender.
Measurements (all in mm, N = 3 unless otherwise stated)
fore femur length 0.55–0.89, width 0.25 (N = 1), fore tibia
length 0.64–0.95, width 0.09 (N = 1), fore rst tarsomere
length 0.40–0.44 (N = 2), mid femur length 0.70–0.92,
mid tibia length 0.72–0.90, hind femur length 1.07–1.22,
width 0.14 (N = 1), hind tibia length 1.14–1.22, width
0.13 (N = 1), hind rst tarsomere length 0.50–0.62.
Abdomen: Length 2.7 mm (N = 1). Brown, conical.
Terminalia in lateral view as in Fig. 31.
Dilophus sp.
Figs 10, 11, 32–34
Previously examined material. female, MHNN 711.
Material, females. JS-Baltic-010, in piece of am-
ber 20×12×5 mm; JS-Baltic-011, in piece of amber
29×17×3 mm.
Two female specimens, belonging to the Dilophus
febrilis-group, with 9 agellomeres, so not tting any
of the previously described species which have 6–7
(Dilophus crassicornis) or 12 (Dilophus pseudofebrilis
and Dilophus succineus) agellomeres. They are likely to
be conspecic with the poorly preserved specimen treat-
ed as Dilophus sp. by Skartveit (2009: 38). As the other
species of Dilophus from Baltic amber are based on male
specimens I nd it not advisable to formally name this
species at the present stage of knowledge. Males of this
species, should they appear, should be recognizable by
characters of the antenna and fore tibia.
Total length 4.55–5.68 mm. Body and legs entirely
dark brown.
Head (Fig. 33): Length 0.68–0.80 mm. Occiput, frons
and gena all with strong, erect, relatively dense setae.
Complex eye about half as long as head, somewhat pro-
truding, with short and ne, rather dense intraocular pile.
Ocellar triangle rather tall. Flagellum 9-segmented, 0.35–
0.40 mm long, 0.06–0.08 mm wide. Palp shorter than an-
tenna, with last segment conical, about 2.5 times as long
as wide, bearing relatively long setae.
Thorax: Length 1.42–1.52 mm (N = 2), width 0.93 mm
(N = 1). Pronotal spine comb with 12 evenly spaced,
medium-length, erect, sharp spines. Mesonotal spine
comb with about 16 small, sharp spines. Mesonotum
moderately shiny with uniserial, short and ne dorsocen-
tral setae (about 15 on each side), otherwise mostly bare.
Scutellum evenly clothed with ne, short setae. Haltere
dark brown with pale stem.
Figure 32. Dilophus sp., female, wing. Scale bar: 1 mm.

Dtsch. Entomol. Z. 68 (1) 2021, 81–99
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97
Figure 33. Dilophus sp., female, head. Scale bar: 0.1 mm.
Figure 34. Dilophus sp., female, fore tibia. Scale bar: 0.1 mm.
Legs: Black with medium-length, dark setae. Protib-
ia (Fig. 34) with four sharp, semi-erect mesal spines, the
two most basal ones close-set, the two more distal sepa-
rated by about one spine length. Apical circlet with eight
sharp spines. Mid and hind legs slender throughout. Fore
femur 0.63–0.72 mm long, 0.23 mm wide (N = 2), fore
tibia 0.75 mm long, 0.10 mm wide (N = 1). Mid femur
1.03 mm long (N = 1). Hind femur 1.13–1.57 mm long
(N = 2), 0.17–0.18 mm wide (N = 2), hind tibia 1.12–
1.60 mm long, 0.08–0.12 mm wide, hind rst tarsomere
0.41–0.53 mm long, 0.05 mm wide.
Wing (Fig. 32): Rather crumbled in the newly ac-
quired specimens. The specimen studied by Skartveit
(2009) with wing as in Fig. 32, wing length 4.4 mm.
Almost hyaline, costa and R-veins dark brown, more
posterior veins lighter brown but still distinctive. All
veins are ne, no conspicuous thickenings. Costa with
biseriate, rather dense, pale setulae, basally about as
long as the width of the costal cell, decreasing in length
apicad. Costa extends to about half-way between apices
of R4+5 and M1. Pterostigma oval, brown, distinctive.
Humeral vein present, subcosta ne, straight, running
well separated from R1 in entire length. Basal R and
R1 dorsally with uniserial, ne, dark setulae which are
about as long as the width of the vein and separated by
about as much as their length, veins otherwise bare. Ra-
dial sector about one-third the length of crossvein R-M.
R4+5 gently curved. Area between R4+5 and M1 about 1.5
times as wide as fork of M. M-veins apically straight.
Crossvein M-CuA meets M well basad of furcation.
CuA with rather long stem and short fork, CuA2 api-
cally a little curved basad. CuP running approximate-
ly parallel to CuA, rather indistinctive. A1 apparent on
stem of wing only.
Abdomen: Strongly swollen in specimen at hand,
membraneous areas stretched. This is presumably be-
cause it is egg-lled. Tergites and sternites clad with
short, dark setae.
Discussion
Bibio succineus is the rst Bibio species formally named
from amber fossils. This is a bit peculiar since the genus
is common to abundant in Tertiary compression fossils
from Europe (e.g., Skartveit and Pika 2014; Skartveit and
Nel 2017) and other bibionid genera are known from nu-
merous amber specimens. It may have to do with habitat
preferences. In the recent, European fauna, 32 species
are known in the genus Bibio (Skartveit 2013), of these
only four (Bibio clavipes, B. handlirschi, B. nigriventris
and B. varipes) are normally found in closed forest habi-
tats (Skartveit, personal observation). On the other hand,
species of the genus Dilophus, which are not that rare in

dez.pensoft.net
John Skartveit: Baltic and Rovno amber Bibionidae98
amber fossils, are also not commonly found in forests in
the recent fauna. Most Bibio species are fairly large-sized
(most are > 6 mm), and amber fossil samples are strongly
biased towards small-sized specimens, this may also be
part of the explanation.
While there are many similarities between the faunas of
Baltic and Rovno amber (e.g., Szwedo and Sontag 2013),
there may also be some dierences (Perkovsky et al. 2010).
Bibionid ies are often widespread, and they also appear
to be quite persistent in time (e.g., Wedmann and Skartveit
2020; Skartveit and Wedmann 2021), thus it is not surpris-
ing that a species described from Baltic amber also turns
up in Rovno amber, even if this may have been deposited
further south than Baltic amber (Mänd et al. 2018).
Although amber fossils may be excellently preserved
with anatomical structures visible in great detail, in most
specimens some traits are not visible because of opaque
emulsions (Verlumung), because they are covered by
other body parts or because they have been deformed
(e.g., crumbled wings). For abundant taxa there may be
a large number of specimens available to pick from, but
for less abundant taxa such as Bibionidae the taxono-
my may have to rely upon less-than-perfect specimens.
When this is the case, nding new specimens of already
described species oers an opportunity to gradually im-
prove the knowledge of the taxon. This is so with all
fossil materials, with the possible exception of limited
outcrops which are no longer available for sampling,
any fresh set of specimens found oers an opportunity
to improve upon the taxonomy of any group, and any
fossil classication should be viewed as preliminary,
pending the discovery of new material.
Presently, a large fraction of the Baltic amber mate-
rial available has been treated with an autoclave to im-
prove the transparency and general appearance of the
amber (Hoeins 2012). Unfortunately, this may alter
the appearance of the specimens in fairly unpredictable
ways, and may destroy much taxonomically relevant in-
formation (Hoeins 2012).
Acknowledgements
Christel and Hans-Werner Hoeins, Hamburg kindly
made material from their collection available for study,
including the new specimens of Hesperinus electrus and
Dilophus clavicornus. The female specimen of Bibio
succineus was made available to me by Friedrich Ker-
negger, Hamburg. The other specimens here described
were acquired through the internet stores http://www.
ambertreasure4u.com and https://www.amberinclusions.
eu/. Digital images were kindly provided by Christel
and Hans-Werner Hoeins (Figs 1, 3, 9), Marius Veta
(Figs 2, 4, 5, 8) and Jonas Damzen (Figs 6, 7, 11). Thanks
are also due to Frank Menzel, SDEI, Müncheberg for fa-
cilitating the museum deposit of the type material. Two
referees provided useful and constructive criticism on the
rst submission of this paper.
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