Baetis zdenkae sp. nov., a new representative of the Baetis buceratus species-group (Ephemeroptera: Baetidae) from Rhodos (Greece) with notes to species-grouping of the subgenus Baetis Leach, 1815 s. str.
Author
Soldán, Tomáš
Author
Godunko, Roman J.
text
Zootaxa
2009
1972
1
19
journal article
10.5281/zenodo.185067
7efbee4b-7750-4ee7-a58b-5aac245f8daa
1175-5326
185067
Baetis
(
Baetis
)
zdenkae
Soldán and Godunko
,
sp. nov.
(
Figs 1–29
)
Description.
Male imago
. Size: body length:
5.8–6.3 mm
; fore wings length:
5.6–6.2 mm
; cerci length:
10.6– 13.8 mm
; tarsal segments: T1 =
0.68–0.72 mm
; T2 =
0.54–0.57 mm
; T3 =
0.32–0.34 mm
; T4 =
0.23–0.25 mm
; general relative tarsal segments length ratio: 1>2>3>4.
General body color light, yellowish-brown to brown. Head brown with darker smudges laterally. Antennae brown, flagellum slightly paler. Ocelli whitish-brown at the apex with brown bases. Eyes black, surrounded by a light ring, occasionally with some yellowish smudges basally. Turbinate eyes oval in dorsal view with convex external margins. Facetted surface yellowish-brown to light brown. Distal part of stalk with narrow yellow ring; central part slightly darker, dirty-yellow, basal brown ring well distinguished (
Figs. 1, 2
). Thorax darker than head, yellowish-brown to brown, with light to dark brown maculation along sutures. Pronotum and distal part of mesonotum yellowish-brown to brown, proximal part distinctly brown. Thoracic sterna light brown to brown. Wings hyaline, transparent. Fore wings with slightly opaque pterostigma.
Hind
wings with costal process small, acute and rounded at apex with three simple longitudinal veins with two free veins in the third field, second vein occasionally with distal bifurcation, third vein relatively short, length about 0.38–0.40 of wing (
Figs. 3, 4
). Fore legs light brown, femora with diffuse smudges distally, middle and hind legs yellow to yellowish-brown.
Abdominal terga with small brownish lateral smudges. Tergum I brown, terga II–VI whitish-yellow with a pair of diffuse central brownish smudges, terga VII–X distinctly darker, yellowish-brown, with narrow elongate central spots. Sterna whitish-yellow to dirty yellow with elongate whitish central spot on segments VII– VIII.
Genitalia pale, yellowish-white to dirty yellow. Forceps distinctly bent up at approximately 45° angle in lateral view (
Fig. 7
). Basal segment about as long as wide without a posteromedial projection, segment 1 elongate conical with slightly convex external margin, segment 2 narrow at the base, slightly expanded distally (widened part as long as 2/3–3/4 of the segment length), segment 3 elongate, slightly longer than wide (
Figs. 5, 6
). Cerci whitish-grey to dirty yellow, first 4–7 segments light brown.
Female imago
. Size: body length:
6.5 mm
; fore wings length:
6.2 mm
; cerci length:
13.2–13.4 mm
.
General body color yellowish-brown to brown. Head uniformly brown. Eyes black with yellowish maculations. Ocelli yellowish with black bases, antennae brown.
Thorax yellowish-brown to brown with dark brown smudges on mesonotum. Sterna whitish-yellow to light brown. Legs yellowish-brown to light brown, fore legs darker. Wings transparent, hyaline, fore wings with distinct yellowish-brown venation, hind wings similar to male, veins darker.
FIGURES 1–4.
Baetis zdenkae
sp. nov.
, male imagoes, paratypes: 1, head (lateral view); 2, head (dorsal view); 3, hind right wing (dorsal view); 4, hind left wing (dorsal view).
Abdominal terga uniform, yellowish-brown to light brown, sterna paler. Cerci light brown to whitish-yellow, darker at bases.
Mature larva
. Size: body length:
5.4–7.5 mm
(male),
5.8–8.5 mm
(female); cerci length: 2.0–
3.3 mm
.
General body color dark, light brown to dark brown. Head yellowish-brown to brown, frons and clypeus paler. The whole head surface covered with short setae and solitary bases of setae. Surface of clypeus with numerous setae. Eyes black, developing turbinate eyes light brown to brown, surrounded by a narrow yellowish ring. Antennae whitish-yellow to light brown, flagellum paler than pedicel and scape, with numerous fine hairs. Pedicel surface with short setae only, scape surface with solitary setae concentrated distally. Labrum relatively wide (width/length ratio 1.52–1.55), with 1 + 4–7 long submarginal bristles and a few pointed lateral setae (
Figs. 9
,
13
). Mandible incisors as in
Figs 8
a, b. Tip of maxillary palpus conical with barely visible, small apical spine, surface with numerous fine hairs (
Fig. 14
). Segment 2 of labial palpus relatively broad with slightly concave inner margin, about twice as broad at apex than at base, distomedial lobe as wide as about 1/ 3 of segment 3 at the base. Segment 3 slightly asymmetrical, slightly longer than 1/2 length of segment 2. The length/width ratio of segments 2 and 3 combined is 1.8–2.1 (
Fig. 10
). Glossae and paraglossae wide, robust. Paraglossae with 3 regular rows of long bristles apically, basal row consisting of at least 16 bristles (
Figs. 11
a, b).
FIGURES 5–7.
Baetis zdenkae
sp. nov.
, male imagoes, paratypes: 5–6, forceps (ventral view); 7, tip of abdomen (lateral view).
Thorax dark, light to dark brown, pronotum with a pair of large pale subtriangular areas laterally, mesonotal color pattern as in
Fig. 17
. Metanotum brownish with central pale spot. Thorax surface with numerous fine hairs and slender spatulate setae rounded apically (
Fig. 15
). Sterna pale, yellowish to light brown. Legs yellowish to light brown with distinct large central dark spot on all femora (occasionally with relatively small central spot). Tibiae with brown distal spots (occasionally only with diffuse brownish smudges), tarsi darker distally. Outer margin of femora with a single, sparse row of large spatulate bristles alternating with fine hairs and small submarginal spatulate setae (
Fig. 16
). Spatulate bristles relatively short and robust, distinctly rounded at apex, distal portion with shallowly splintered margins (
Figs. 18, 19, 21
). Femora with (1) slender spatulate setae with convergent margins (
Figs. 18–20
) and (2) relatively wide and apically rounded spatulate setae with subparallel margins (
Fig. 21
). Submarginal spatulate setae of distal portion of femora with splintered margins. Inner margin of femora with uniform row of small pointed spines and fine hairs; all surface of femora with spatulate setae and fine hairs (
Fig. 22
). Outer margins of tibiae with deeply splintered, slender spatulas alternating with fine hairs (
Fig. 23
). Inner margins with irregular row of spines and fine hairs (
Fig. 24
). Outer margins of tarsi with small pointed spines and hairs; small submarginal spatulate setae, with distally splintered edges. Inner margins with large pointed spines; splintered submarginal spatulate setae, and fine hairs. Surface of tarsi with numerous hairs and splintered spatulate setae. Tarsal claws elongate, relatively slender with at least 10 teeth, without subapical setae (
Figs. 12
,
25
).
FIGURES 8–12.
Baetis zdenkae
sp. nov.
, mature larvae: 8, left (a) and right (b) mandibular incisors; 9, labrum (dorsal view); 10, labial palpus (ventral view); 11, paraglossa (a) and glossa (b); 12, tarsal claw (hind leg).
FIGURES 13–16.
Baetis zdenkae
sp. nov.
, mature larvae: 13, labrum (dorsal view); 14, apical portion of the last segment of maxillary palpus; 15, arrangement of spatulate setae on the surface of thorax; 16, outer margin of femur (hind leg). Scale bars: 13 = 500 nm; 14, 15 = 100 nm; 16 = 500 nm.
Abdominal terga dark, yellowish-brown to brown, color pattern as in
Fig. 17
, muscle insertions pale (cf.
Jacob 2003
), posterior margins with broad triangular bluntly pointed teeth alternating with setae (
Fig. 28
), surface with numerous fine hairs, wide bases of hairs and small spatulate setae. Two distinct
types
of spatulate setae discernible on abdominal tergal surface: (1) elongate narrow ones with lateral convergent margins, and (2) relatively rare ones with subparallel or divergent lateral margins, rounded at apex (
Figs. 26, 27
). Sterna uniform, yellowish-brown to brown with a pair of short transversal divergent strokes near the anterior margins. Inner margin of paraprocts with a single row of at least 10 (usually 12–15) distinct teeth (
Fig. 29
), surface with fine hairs and sparse spatulate setae. Gills 1 and 7 slightly asymmetric and subequal in size. Gills 2– 6 asymmetric and distally rounded. Both outer and inner gill margins with small teeth alternating with fine hairs. Cerci uniform, yellowish-brown to brown, paracercus shorter by 1/2.
Male and female subimagos unknown.
Etymology
. The species is named for Zdenka, wife of the senior author, to acknowledge her distinguished field assistance during sampling of mayflies on Rhodos.
Types
.
HOLOTYPE
: male imago,
GREECE
, Rhodos (Rodos)
Island
, stream at the Kremastis Bridge in Kremastí, about
14 km
SW of Rhodos City, about
3 km
NE of the Diagoras International Airport and about
500 m
from its mouth to the Aegean Sea at about
10 m
a. s. l.,
May 28, 2005
.
PARATYPES
:
6 male
imagoes,
1 female
imago,
275 larvae
, same locality and collection date as
holotype
.
FIGURE 17.
Baetis zdenkae
sp. nov.
, mature larva, general view of body (dorsal view).
Further material examined (no
types
).
256 larvae
,
GREECE
, Rhodos (Rodos)
Island
, same locality and collection date as
holotype
;
8 larvae
,
Greece
, Rhodos Island, Argiros Potamos (stream), about
30 km
SW of Rhodos City,
1 km
NE of Kalavárda and about
1 km
from its mouth to the Aegean Sea at about
10 m
a. s. l.,
May 26, 2005
.
FIGURES 18–21.
Baetis zdenkae
sp. nov.
, mature larvae, outer margin of femora (hind legs). Scale bars: 18 = 200 nm; 19 = 100 nm; 20, 21 = 100 nm.
All material (preserved in 70% alcohol) was collected by Zdenka and Tomáš Soldán. Genitalia of two male imagoes on slides.
Holotype
, most
paratypes
and other material examined deposited in collection of the Biological Centre, Academy of Sciences of the
Czech Republic
, Institute of Entomology, Č eské Budĕjovice,
Czech Republic
;
50 larvae
and
1 male
imago (all
paratypes
) deposited in the State Museum of Natural History, National Academy of Sciences of
Ukraine
, Lviv,
Ukraine
.
The comparative material of
B. buceratus
was collected in Central
Bohemia
(the Berounka River basin),
Slovakia
and
Ukraine
(the Latorica, Tisza and Dniester River basins) at numerous localities. Larvae and adults of
B. nexus
were collected at several localities of the Dyje (Thaya) River basin in Moravia (
Czech Republic
),
Slovakia
and
Ukraine
(the Latorica and Tisza River basins). For descriptions of some localities see
Landa
and Soldán (1989)
,
Soldán and Zahrádková (2000)
, and
Horsák (2001)
. Material of
B. spei
was not studied, morphological characters and other data are based on the original description by
Thomas and Dia (1985
,
2007
).
Differential diagnosis and affinities.
B. zdenkae
sp. nov.
can be easily distinguished from the other three representatives of the
B. buceratus
species-group (
B.
(
B.
)
buceratus
Eaton, 1870
,
B.
(
B.
)
nexus
Navás, 1918
, and
B
. (
B.
)
spei
Thomas & Dia, 1985
) by the following combination of morphological characters:
in male imago
: (1) facetted surface of turbinate eyes yellowish-brown to light brown (yellowish brown to orange brown in
B. buceratus
, dark brownish in
B. nexus
and flesh-colored in
B. spei
), (2) tricolor combination of stalk of turbinate eyes (stalk paler, light orange in
B. buceratus
, eyes unicolorous in
B. nexus
, stalk flesh-colored in
B. spei
with diffuse and intermittent basal ring), (3) third vein of hind wings relatively short, about 0.38–0.40 wing length (about half of wing length in
B. buceratus
, 1/2 length to longer in
B. nexus
), (4) forceps conspicuously bent up in lateral view (as in
B. buceratus
, nearly straight in
B. nexus
and
B. spei
), (5) basal segment of forceps without posteromedial projection (posteromedially produced into lobe-like projection in
B. buceratus
,
B. nexus
and
B. spei
), and (6) segment 1 of forceps elongate conical (conical in
B. buceratus
and
B. spei
, oval, bulbous with apparently convex inner and outer lateral margins in
B. nexus
);
in larva
: (7) structure of segments 2 and 3 of labial palpi (segment 3 shorter than or equal to 1/2 of segment
2 in
B. nexus
), (8) structure of mandible incisors (cf. e.g., our
Figs. 8
a, b with
Fig.
3
g, d by
Thomas and Dia 1985
: 242 showing
B. spei
), (9) paraglossae with basal row of apical bristles consisting of at least 16 bristles (about 10–12 bristles in
B. spei
), (10) outer margins of femora with single sparse row of spatulate bristles, alternating with fine hairs and submarginal small spatulate setae (as in
B. spei
), (11) structure of small spatulate setae of femora (some of them conspicuously splintered as in
B. spei
), (12) arrangement of small spatulate setae on dorsal surface of femora, (13) posterior margins of abdominal terga with broad bluntly pointed triangular teeth, alternating with setae (teeth rounded, semicircular in
B. spei
, narrow triangular blunt pointed teeth in
B. buceratus
), (14) surface of terga with numerous fine hairs, spatulate setae, and wide bases of hairs and spatulate setae (without spatulate setae in
B. spei
), (15) inner margin of paraproct with 10–15 distinct teeth (about 20–25 teeth of different shape in
B. spei
; about 20 teeth in
B. buceratus
and
Thomas and Dia 1985
: 243,
Fig. 12
; about 25 teeth in
B. nexus,
Müller-Liebenau 1969
: 149
, Abb. 109), (16) paracercus shorter than cerci by 1/2 (subequal in
B. buceratus
and
B. nexus
, about 2/3 of cerci in
B. spei
), and (17) specific color pattern of thorax and abdomen in dorsal view (e.g., a single, conspicuous pale band in the middle of pronotum in
B. spei
, in
Thomas and Dia 1985
: 243,
Fig. 7
).
The male genitalia of
B. zdenkae
sp. nov.
are similar to
B. buceratus
, in the structure and proportions of segments 1–3, and conspicuously bent up forceps (see
Müller-Liebenau 1969
: 140, Abb. 99–100 or
Jacob 2003
: 96, Abb. 17a–b). On the other hand, the male imago of the new species differs markedly from
B. buceratus
in color pattern of the facetted surface of the turbinate eyes and their stalks and in hind wing venation (cf. characters 1–3, see also
Müller-Liebenau 1969
: 139–140, Abb. 104j or
Jacob 2003
: 97). On the other hand,
B. zdenkae
sp. nov.
can be easily distinguished from
B. nexus
by the different arrangement of all critical imaginal characters (1–6, see above and cf.
Müller-Liebenau 1969
: 146–147, Abb. 101, 107, and 108, or
Jacob 2003
: 98, Abb. 17c).
Larvae of
B. zdenkae
sp. nov.
can be distinguished from all remaining representatives of the
B. buceratus
species-group by the combination of characters (9 and 14), and, particularly really the critical characters (8 and 16) separate this species from
B. buceratus
and
B. nexus
. Additionally,
B. zdenkae
sp. nov.
differs from
B. nexus
by the structure of outer margin of femora and paraproct (characters 10 and 15). The latter two characters and the arrangement of triangular teeth on the posterior margin of abdominal terga (character 13), distinguish the new species from
B. spei
with small rounded, nearly semicircular teeth, cf.
Thomas and Dia (1985: 243:
Fig. 11
)
. Contrary to
B. spei
(muscle insertions on head well visible and contrasting), the head of
B. zdenkae
sp. nov.
, is rather unicolorous. Labrum of
B. zdenkae
sp. nov.
, provided with 1 + 4–7 bristles is relatively wider (width/length ratio 1.52–1.55) vs. 1 + 6–8 bristles and width/length ratio
1.35–1.50 in
B. spei
. Further differences between
B. zdenkae
sp. nov.
,
B. buceratus
and
B. spei
can be found also in thoracic and abdominal terga color patterns (see
Müller-Liebenau 1969
: 141–145 and 147–150, Abb. 102–103, 109 or
Jacob 2003
: 96–98, Abb. 3l, 18, 19, and
Thomas and Dia 1985
for details).
Biology.
Larvae of
B. zdenkae
sp. nov.
evidently prefer stream run places of the “lowland” biotopes within the island. These localities (mostly at elevations of
100–250 m
a. s. l.) were inhabited by other baetid species, e.g., by apparently dominant
Baetis (Nigrobaetis) digitatus
(
Bengtsson, 1912
)
which is the first faunistic record from Rhodos and
P. fascicaudale
,
but no larvae of
B. zdenkae
sp. nov.
have been collected. Larvae of this new species were found in two streams with permanent water of about
1–3 m
across and an average depth of
10–30 cm
, moderate to fast current velocity and stony bottom overgrown, in some places, with submerged aquatic vegetation. The current velocity was about
20–50 cm
.s -1 at the most densely inhabited places, the density of larvae, roughly estimated at about 100–300 ind.m -1, decreased rapidly with decreasing current velocity, places with slower current were inhabited rather sparsely. Water temperature ranged from 17 ºC early in the morning to 23–26.5 ºC in the afternoon at sun-exposed, densely inhabited places (
type
locality, up to 28.5 ºC in pools with very rare occurrence of larvae). As to substrate roughness, larvae preferred gravel places (lithal) covered with cobble and pebble. Their densities in places covered with granules (2.0 mm in diameter) and very coarse (1.0 mm) or coarse (
0.5 mm
) sand were very low showing rather incidental occurrence. Larvae were not found on fine substrates like medium to very fine sand or silt. If submerged aquatic plants occurred at the places preferred, larval densities among vegetation were comparable with those of stony habitats. However, substrate requirements of larvae do not seem to be pronounced. Stream banks are regulated at numerous places in both biotopes inhabited. For instance, the Argiros Potamos near Kalávarda is a very shallow stream with an artificial concrete streambed in some places.
FIGURES 22–25.
Baetis zdenkae
sp. nov.
, mature larvae: 22, surface of femur; 23, outer margin of tibia; 24, inner margin of tibia; 25, tarsal claw (hind legs). Scale bars: 22–24 = 200 nm; 25 = 500 nm.
At the
type
locality, larvae of
B. zdenkae
sp. nov.
are clearly dominant forming at least 75% of the mayfly standing crop, they seem to be very rare at the locality of the Argiros Potamos (at most 10% of the mayfly standing crop in May,
Caenis luctuosa
(
Burmeister, 1839
)
and a new species of the
B. lutheri
species-group were dominant). At the
type
locality, the larvae were collected together with those of
C. luctuosa
,
P. fascicaudale
and
B.
(
Rhodobaetis
) cf.
rhodani
(
Pictet, 1843
)
.
The life cycle of
B. zdenkae
sp. nov.
remains unknown in detail. However, judging from the size of larvae in
May 2005
and timing of mating flight we might suppose a seasonal, bivoltine winter life cycle, the MBws
type
according to the classification by
Clifford (1982)
. Adult emergence by mid May indicates a possibility of two generations a year (second generation might fly from late August to early October). Owing to favorable conditions (generally mild climate, relatively high water temperatures) there is a chance to complete development of larvae originating from the eggs laid in May of the same year. Taking into account approximately linear growth of larvae during winter followed by its acceleration after spring warming of water, and the different size categories of larvae collected at the same time in May, several egg cohorts are likely, as in numerous other mild climate
Baetis
species (cf.
Sowa 1975
or
Clifford 1982
)
FIGURES 26–29.
Baetis zdenkae
sp. nov.
, mature larvae: 26, surface of abdominal tergum IV; 27, surface of abdominal tergum VI; 28, posterior margin of abdominal tergum IV; 29, outer margin of paraproct plate. Scale bars: 26–29 = 20mm.
Subimagines emerge from the water surface and places overgrown with submerged vegetation during daylight hours, from about 10.00 a.m–16.00 p.m. local time.
Baetis zdenkae
sp. nov.
showed early morning mating flight activity with the mating flight generally occurring from about 6.30–8.30 a.m. local time. First males started to appear approximately a half hour before sunrise, and showed a typical “pendular” flight pattern usually in groups of about 3–10 individuals, females were observed about 0.5–1 hour later. Although only a few females were observed flying upstream, their flight activity seemed to last at least one hour after males had disappeared. A single female was observed ovipositing on a submerged stone, hence the way of oviposition seems to be similar to other species of the genus
Baetis
.
Generally, the biology of
B. zdenkae
sp. nov.
resembles that of
B. spei
which was characterized as a rhithro-potamal species by
Thomas and Dia (1985)
, while the remaining representatives of
B. buceratus
species-group occur at rather different (mostly potamal) habitats. However, larvae of
B. spei
showed a wider range of vertical distribution than those of
B. zdenkae
sp. nov.
being collected at altitudes of
5–950 m
a. s. l. at places
2–48 km
from source in well oxygenated water. They were moderately abundant to abundant at streams about
3–10m
across, including also a temporary stream. The larvae were characterized as thermophilous (in contrast to those of
B. bisri
Thomas & Dia, 1983
and
B. baroukianus
Thomas & Dia, 1984
living at the same area (
Thomas & Dia 1983
,
1984
), maximal water temperature ranged from 17–29 ºC (pH 7.4–8.25), conductivity 290–440 µS.cm -1. The life cycle of
B. spei
is not fully known, mature larvae were collected from May to August (
Thomas & Dia 1985
), were collected from May to August (
Thomas & Dia 1985
), and adults were collected at the same time (
Thomas & Dia 2007
).
Larvae of
B. buceratus
have been found mostly at the localities of large lowland rivers (epipotamal). They apparently can tolerate a certain degree of pollution being sometimes dominant at these biotopes. Larvae prefer medium to high current speed and stony substrata (gravel and larger stones) but often occur also among submerged plants. Such habitats are described as typical for this species (
Buffagni & Desio 1994
; Gonzáles del
Tánago 1984
).
B. buceratus
shows a typical bivoltine winter life cycle (MBws) with overwintering larvae of the first generation. However, there are some data indicating plasticity of the cycle. In
Switzerland
, larvae live also in epirhithral stream segments although they prefer lower elevations and places with lower current velocity at this area (
Sartori & Landolt 1999
). According to
Landa
(1968)
older larvae of the first generation appear from March to May – this may indicate ceasing of larval development during winter months rarely found in species with the MBws life cycle
type
. According to
Haybach (1998
,
2006
) there is one overwintering generation with flight period in spring and two generations following late summer and autumn. Since the adults apparently fly from July to October (
Landa
1968
;
Langford 1971
;
Sowa 1975
), two “summer” generations and, consequently, some
type
of polyvoltinism (MP) cannot be excluded.
Larvae of
B. nexus
live in lowland waters of different size, being mostly found in rivers, their backwaters and artificial freshwater biotopes (e.g., in the “roach zone”), at places with very low current velocity. They evidently prefer places rich in submerged aquatic vegetation. Azonal species according to
Haybach (1998
,
2006
), habitat preference cannot be evaluated from the rhithron-potamon concept. However, in south Moravia (
Czech Republic
), the larvae are usually found in a typical epipotamal river, moreover influenced by the upstream impoundment (
Horsák 2001
) like they do in southern
France
(Cammouseight &
Fontaine 1990
, see this paper also for further details on ecological requirements of larvae and their quantitative presentation). Seasonal bivoltine winter life cycles (MBws) have been observed in
France
(Cammouseight &
Fontaine 1990
), with two flight periods in May and August, and also in
Hungary
(
Ujhelyi 1966
),
Germany
(
Haybach 1998
,
2006
) and
Poland
(
Keffermüller 1972
).
Distribution.
Since
B. zdenkae
sp. nov.
is so far known only from Rhodos Island it might be considered endemic to this island. However, the true distribution of
B. zdenkae
sp. nov.
still remains poorly known so that its classification is preliminary since these possible “endemics” might inhabit a much larger area as shown, for example, by our finding of presumably “endemic” species
B. mirkae
group described from
Cyprus
also on Rhodos (
Soldán & Godunko, 2008
). That is why we prefer to wait until further collection records are published. The distribution of
B. zdenkae
sp. nov.
can be compared to that of
B. spei
, the species known only from
Lebanon
, only from two river basins (Nahr el Aouali and Nahr ed Damour) as well, so far altogether from 9 localities (
Thomas & Dia 1985
).
On the other hand the distribution of
B. zdenkae
sp. nov.
seems to be quite different from the distributions of
B. buceratus
and
B. nexus
. The former species (
type
locality the Kenneth and Holybrook near Reading, Berkshire,
England
) belongs to widely distributed Westpalaearctic species. It is known from Europe including the British Islands and some Mediterranean islands, e.g., Sardinia (
Belfiore & Gaino 1988
) but probably missing in North Africa. Northern limits are situated in Scandinavia –
Sweden
and
Denmark
(
Bengtsson 1917
;
Jensen 1969
), southeastern ones in
Asia Minor
,
Turkey
and
Iraq
(
Koch 1988
;
Kazanci 1984
;
Al-Zubaidi
et al.
1987
), eastern limits probably in southern Ural, Caucasus and Central Asia (cf.
Kluge 1997
).
B. buceratus
is classified either as a Holomediterranean faunistic element of the expansive
type
according to
Jacob (1972)
, or a Pontokaspian element according to
Haybach (1998)
and its area is sympatric to that of
B. zdenkae
sp. nov.
Baetis nexus
belongs to widely distributed Westpalaearctic species as well, however its area is restricted to about 50º N. Northern limits are situated in
Germany
and
Poland
. This species is known from Europe except for the British Islands, Fennoscandia and most of the Mediterranean, and is missing in North Africa (see
Sartori & Soldán (2006)
for complete list of distributional records). Eastern limits are uncertain, the species has been found easternmost in the Asian part of
Turkey
(
Kazanci 1984
). The species is considered a typical Pontic faunistic element according to
Haybach (1998
,
2003
).