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POLISH JOURNAL OF ENTOMOLOG Y
POLSKIE PISMO ENTOMOLOGICZNE
VOL. 80: 765-777 Gdynia 31 December 2011
DOI: 10.2478/v10200-011-0057-5
A new fossil mosquito, with notes on the morphology and taxonomy
of other species reported from Eocene Baltic amber
(Diptera: Culicidae)
RYSZARD SZADZIEWSKI*,WOJCIECH GIŁKA
Department of Invertebrate Zoology, University of Gdańsk, Piłsudskiego 46, 81-378
Gdynia, Poland; e-mail: *biorys@ug.gda.pl
ABSTRACT. Males of Culiseta gedanica sp. n. and Culex erikae SZADZIEWSKI & SZADZIEWSKA,
1985 are described, and an incomplete male of Coquillettidia is reported from Baltic amber for the
first time. Aedes perkunas PODENAS, 1999 is recognized as a junior synonym of Culex erikae, syn. n.
Aedes serafini SZADZIEWSKI, 1998 is transferred to the genus Ochlerotatus, comb. n. Mosquitoes
are rare fossils in Baltic amber. They represent six species of extant genera with a worldwide
distribution: Culiseta, Ochlerotatus, Coquillettidia, Culex and Aedes. A key to the identification of
males is also provided.
KEY WORDS: Diptera, Culicidae, Eocene, Baltic amber, Gulf of Gdańsk.
INTRODUCTION
The Culicidae is a well-known family of nematocerous flies. Over 3,200 species are known
in the extant world fauna. They are frequent parasites of mammals and birds as females
feed on their blood. Mosquito larvae and pupae inhabit exclusively shallow stagnant waters.
Despite the fact that the phylogenetic history of mosquitoes goes back to the Mesozoic
era, they are rarely preserved as fossils. The oldest true mosquito is reported from Upper
Cretaceous Canadian amber (POINAR et al. 2000). Fossil mosquitoes from the Cenozoic are
reviewed by EDWARDS (1923), STATZ (1944), EVENHUIS (1994) and SZADZIEWSKI (1998).
Mosquitoes are very rare in Eocene Baltic amber (SZADZIEWSKI 1998, PODENAS 1999),
while they are more common in younger Miocene Dominican amber (SZADZIEWSKI &
GROGAN 1994, POINAR 2005).
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766
This paper presents the results of an examination of mosquitoes from the private
collection of Christel and Hans Werner Hoffeins of Hamburg and the Museum of Amber
Inclusions of the University of Gdańsk.
Acknowledgements
We are much indebted to Christel and Hans Hoffeins of Hamburg (Germany) for
arranging the loan of materials. This paper is a contribution to the research grant “Extinct
and extant genera in the palaeontological record of recent families of insects” from the
Ministry of Science and Higher Education of Poland NN 303 2979 37 awarded to RSz for
the years 2009-2012.
MATERIAL, METHODS
Four male mosquitoes from Baltic amber were examined. They are embedded in
artificial resin. For an explanation of general morphological terminology and abbreviations,
see DAHL (1997), SZADZIEWSKI (1998) and BECKER et al. (2010).
SYSTEMATICS
Subfamily Culicinae
Genus Culiseta FELT, 1904
Culiseta gedanica sp. n.
(Figs 1-3)
Diagnosis
The male of the species is characteristic in having prespiracular setae, a larger claw on
the fore and mid legs with a basal and median tooth, and a smaller claw with a basal tooth.
The gonocoxite is simple, not modified, and the gonostylus bears an apical expansion and
distinct tooth (see key).
Description
Male. Body length (without proboscis) 4.6 mm; thorax and abdomen 4.2 mm (Fig. 1A).
Wing length 4.17 mm. Eyes touching, flagellum distorted. Proboscis 2.06 mm long. Palpus
2.63 mm long (Fig. 1B,C); fourth palpomere stout, 0.59 mm long, fifth palpomere slender,
0.48 mm long. Scutellum trilobed. Prespiracular (=spiracular) setae present, postspiracular
absent. Wing vein R3 2.0 times longer than R2+3; veins with slender scales (Fig. 2A). Legs
incomplete: right fore and hind legs missing; left mid leg without tarsus; hind tarsi absent.
Fifth tarsomere of fore leg with strong basal horn-like expansion ventrally (Fig. 2B). Larger
SZADZIEWSKI R., GIŁKA W.: A new fossil mosquito, with notes on morphology and taxonomy
767
claw of fore and mid legs with basal and median tooth, smaller claw with basal tooth (Figs
2B,C). For length of leg segments, see Table 1.
Table 1. Lengths (in mm) of leg segments in male Culiseta gedanica sp. n.
fe ti ta1 ta2 ta3 ta4 ta5
p1 - - 1.03 0.37 0.24 0.12 0.20
p2 1.77 1.89 1.42 0.63 0.40 0.15 0.21
p3 - 1.89 - - - - -
Fig. 1. Culiseta gedanica sp. n., male: A – total habitus, B – palpus, C – head.
Polish Journal of Entomology 80 (4)
768
Fig. 2. Culiseta gedanica sp. n., male: A – wing, B – distal tarsomeres of fore leg, C – distal
tarsomeres of mid leg.
Genitalia (Fig. 3A, B) well preserved. Tergite IX with group of strong short
posteromedian spines. Gonocoxite simple, not modified, slender. Gonostylus distinctly bent
at apex, armed with apical expansion and distinct tooth (Fig. 3C). Claspettes curved with
serrated margins and pointed apices.
Female. Unknown.
Material examined
Holotype male. Hoffeins’ collection #981.3. Syninclusions: two collembolans. The
holotype will be deposited at the Senckenberg Deutsches Entomologisches Institut (SDEI,
Germany).
Etymology
The specific name refers to the Gulf of Gdańsk, where the largest deposits of Eocene Baltic
amber are to be found.
SZADZIEWSKI R., GIŁKA W.: A new fossil mosquito, with notes on morphology and taxonomy
769
Discussion
The new species is included in the extant genus Culiseta as the adult has well visible
prespiracular setae. The new fossil species is distinctly smaller than extant Culiseta and has
unique gonostyli with an apical expansion. This is the first report of a fossil in the genus.
Fig. 3. Culiseta gedanica sp. n., male genitalia, photo (A) and drawing (B, C), C – apex of
gonostylus.
Genus Ochlerotatus LYNCH ARRIBALZAGA, 1891
Ochlerotatus serafini (SZADZIEWSKI, 1998), comb. n.
(Fig. 4)
Aedes serafini SZADZIEWSKI, 1998: 240 (male, Baltic amber).
Notes on morphology
The present re-examination of the holotype resulted in new morphological details,
which were not shown in the original description of the species. They are: Fifth tarsomere
of fore leg with strong basal expansion ventrally. Larger claw of fore and mid legs with
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770
median tooth, smaller claw with basal tooth, claws of hind leg small equal, each with basal
tooth. Tergite IX with group of four setae placed on a spatulate process in caudomedian
position. Base of gonocoxite with distinct ventral swelling; subtriangular expansion at mid
length of inner margin of gonocoxite bearing three stout spine-like setae directed ventrally,
and apical inner lobe (Fig. 4). Gonostyli invisible. Claspettes barely visible.
Fig. 4. Ochlerotatus serafini (SZADZIEWSKI), male genitalia (gonostyli not visible).
SZADZIEWSKI R., GIŁKA W.: A new fossil mosquito, with notes on morphology and taxonomy
771
Material examined
Holotype male of Aedes serafini, Museum of Amber Inclusions, University of Gdańsk,
MAI #112.
Discussion
REINERT (2000) suggested dividing the composite genus Aedes MEIGEN into two genera
Aedes and Ochlerotatus; this proposition was widely accepted, and all subgenera
subsequently received generic status (HARBACH 2011).
The gonocoxite in Ochlerotatus is characteristic in having a distinct apical inner lobe.
Such a lobe, as observed in serafini, is very similar to that found in extant O. excrucians
(WALKER) (present examination), which indicates that this fossil species can be placed in
the extant genus Ochlerotatus.
Two other species of the genus Aedes, described by SZADZIEWSKI (1998) from Baltic
amber (A. hoffeinsorum and A. damzeni), are left in the genus of traditional concept, and
need further materials and studies. They were originally placed in the subgenus Finlaya
THEOBALD, which now is a distinct genus. However, A. hoffeinsorum and A. damzeni
cannot be placed in Finlaya, because in this genus the males have bigger claws on the fore
and mid legs armed with a basal and median tooth, whereas the smaller claw has a basal
tooth (HARBACH 2011). In A. hoffeinsorum all claws are simple, and in A. damzeni the
claws have no basal tooth (SZADZIEWSKI 1998).
Genus Coquillettidia DYAR, 1905
Coquillettidia sp. indet.
(Fig. 5)
Description
Male (Fig. 5A). Hind legs, right wing and genitalia missing. Wing length 2.7 mm.
Fourth palpomere stout (0.47 mm), fifth palpomere slender (0.44 mm). Prespiracular and
postspiracular setae absent. Fifth tarsomere of fore leg with strong basal expansion
ventrally. Scales on wing veins broad (Fig. 5B). Larger claw of fore and mid legs with basal and
median tooth, smaller claw simple, without teeth. For length of legs segments, see Table 2.
Table 2. Length (in mm) of legs segments in male Coquillettidia sp. indet.
ta1 ta2 ta3 ta4 ta5
p1 0.92 0.29 0.20 0.09 0.13
p2 1.37 0.56 0.31 0.12 0.15
Polish Journal of Entomology 80 (4)
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Fig. 5. Coquillettidia sp. indet., male: A – total habitus, B – wing veins with broad scales.
SZADZIEWSKI R., GIŁKA W.: A new fossil mosquito, with notes on morphology and taxonomy
773
Material examined
Hoffeins’ collection, male. #1719-1.
Discussion
The subgenus Coquillettidia was recently removed from the genus Mansonia
BLANCHARD and elevated to a distinct genus (DAHL 1997, BECKER et al. 2010, HARBACH
2011). In the extant European fauna Mansonia is absent, while Coquillettidia is represented
by one species C. richiardii (FICALBI). Larvae and pupae of species from both genera
pierce water plants and take air from plant tissues. They are able to inhabit lakes and ponds
with fish, hiding from predators among plants in the littoral zone. This is the first record of
the genus in Eocene Baltic amber.
Genus Culex LINNAEUS, 1758
Culex erikae SZADZIEWSKI & SZADZIEWSKA, 1985
(Figs 6, 7)
Culex erikae SZADZIEWSKI & SZADZIEWSKA, 1985: 515 (female, Baltic amber, Eocene).
Aedes perkunas PODENAS, 1999: 113 (male, Baltic amber, Eocene), syn. n.
Description
Male. Almost complete (Fig. 6A). Only distal portion of right flagellum missing. Left
side of thorax covered with milky fog. Body length about 5.0 mm (without proboscis).
Flagellum 1.77 mm long, plume well developed; distal flagellomeres 12 and 13 elongated,
each 0.48 mm. Terminal flagellomere armed with cylindrical apical prolongation. Proboscis
2.06 mm. Palpus 2.74 mm; fourth palpomere 0.53 mm long, fifth palpomere 0.45 mm long,
both slender, combined length of 4th and 5th palpomeres 1.56 times longer than 3rd
palpomere (Fig. 6B). Wing length measured from basal arculus 2.98 mm. Vein R2 4.1 times
longer than vein R2+3. Wing scales slender (Fig. 6C). Fifth tarsomere of fore leg with strong
basal expansion ventrally. Larger claw of fore and mid legs with median tooth, smaller
claw with basal tooth, claws of hind leg equal, simple (Fig. 7A-F). For length of legs
segments, see Table 3.
Table 3. Length (in mm) of leg segments in male Culex erikae.
Fe ti ta1 ta2 ta3 ta4 ta5
p1 - - 1.37 0.40 0.21 0.09 0.20
p2 - - 1.77 0.68 0.38 0.14 0.18
p3 1.71 1.94 2.19 1.14 0.78 0.43 0.25
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774
Fig. 6. Culex erikae SZADZIEWSKI & SZADZIEWSKA, male: A – total habitus, B – palpus, C – wings.
SZADZIEWSKI R., GIŁKA W.: A new fossil mosquito, with notes on morphology and taxonomy
775
Fig. 7. Culex erikae SZADZIEWSKI & SZADZIEWSKA, male: A-C – distal tarsomeres of fore (A), mid
(B) and hind leg (C); D-F – tarsal claws of fore (D), mid (E) and hind leg (F); G, H – lateral aspect of
genitalia.
Genitalia (Fig. 7G, H). Observable in lateral aspect. Base of gonocoxite barely visible; a
ventromedian group of four long spatulate spines placed subapically, well visible.
Gonostylus evenly bent, tapering to pointed apex armed with short tooth.
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Material examined
Hoffeins collection, #981-2a. male. Syninclusions in amber piece 2b: Mycetophilidae
and Hymenoptera.
Discussion
The holotype male of Aedes perkunas is not complete: it lacks a hypopygium and hind
legs. According to the original description, the male of this mosquito has the claws of the fore
and mid legs unequal, and the larger one is armed with a median tooth. This character is
usually present in extant and fossil Culex, Ochlerotatus and Aedes. However, in the examined
males of these genera, the smaller claw has a basal tooth. We suspect that this character was
overlooked in the species described by PODENAS (1999), as was the basal-ventral tubercle on
the fifth tarsomere of the fore leg, which is usually present in male mosquitoes. The male of
Aedes perkunas, devoid of genitalia, is similar to O. serafini and Culex erikae. We took into
consideration the proportions of the palpomeres (3rd / 4th + 5th), which in A. perkunas and C.
erikae are the same (1.6), whereas they differ distinctly from that found in O. serafini (1.9).
Thus we propose to treat A. perkunas as a junior synonym of C. erikae.
Key to male mosquitoes from Baltic amber
1. Wing veins with broad scales (Fig. 5B) ........................................ Coquillettidia sp. indet.
-. Wing veins with slender scales (Fig. 2A) .......................................................................... 2
2. Prespiracular setae present. Larger claw of fore and mid leg with basal and median tooth
(Fig. 2B, C) ...............................................................................… Culiseta gedanica sp. n.
-. Prespiracular setae absent. Larger claw of fore and mid leg simple or with median tooth,
basal tooth absent (Fig. 7D, E) ......................................................................................… 3
3. Gonocoxite with a group of subapical spatulate spines on ventromedian surface (Fig. 7G, H)
…………………….………………… Culex erikae SZADZIEWSKI & SZADZIEWSKA, 1985
-. Gonocoxite simple, without modifications ........................................................................ 4
4. Palpus shorter than proboscis …………...……. Aedes hoffeinsorum SZADZIEWSKI, 1998
-. Palpus longer than proboscis ….…………………………………....…………………… 5
5. Fourth palpal segment slender, fifth one short .......... Aedes damzeni SZADZIEWSKI, 1998
-. Fourth palpal segment stout, fifth one long ... Ochlerotatus serafini (SZADZIEWSKI, 1998)
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Received: December 6, 2011
Accepted: December 18, 2011