Corresponding author: Ľuboš Hrivniak (lubos.hrivniak@gmail.com); Roman J. Godunko (
Academic editor: B. Price
The Caucasus and adjacent areas are inhabited by fifteen species of mayflies of the genus
Hrivniak Ľ, Sroka P, Bojková J, Godunko RJ (2020) Identification guide to larvae of Caucasian
The knowledge facilitating the identification of mayflies inhabiting the Caucasus biodiversity hotspot (
General morphology of
The global diversity of
Individual species of
We aim to provide information necessary for the accurate species identification of
Larvae of
Topographic map of the Caucasus and adjacent mountain ranges with the position of the study area (upper left part) and distribution of our sampling sites (upper right part). Geographical coverage of identification guide of
Original descriptions of individual species were used for the initial species identification based on morphology (
Body parts with morphological structures requiring microscopical examination (i.e., mouthparts, femora, abdominal terga) were mounted on slide using HydroMatrix® (MicroTech Lab, Graz, Austria) mounting medium. In order to remove the muscle tissue for an investigation of the cuticular structure, the specimens were left overnight in a 10% solution of NaOH prior to slide mounting. Drawings were made using a stereomicroscope Olympus SZX7 and a microscope Olympus BX41, both equipped with a drawing attachment. Photographs were obtained using Leica DFC450 camera fitted with macroscope Leica Z16 APO and folded in Helicon Focus version 5.3. All photographs were subsequently enhanced with Adobe Photoshop™ CS5. The terminology was used mostly according to
A set of larval diagnostic characters used in the identification guide (listed below) was derived from
Morphological characters for the larval identification of
The coloration pattern of abdominal terga and/or sterna is often species-specific and valuable in the species identification of
Except
Denticles along posterior margin of abdominal terga are pointed and irregular in size in all Caucasian
Mouthparts of Caucasian
The shape of gill plates I–VI is more or less identical between individual species. However, the gill plate VII is specific for some species; e.g., narrow, banana-shaped plate in
Denticulation of tarsal claws was omitted in the guide, due to its high overlap among species and frequent abrasion. Tarsal claws of all species usually possess 2–4 denticles.
The shape of head (in dorsal view) may be used as one of the diagnostic characters in some species; e.g.,
We also figure a shape of medial emargination of female sternum IX and spatulate setae on dorsal surface of femora (figures in the guide include the variability from proximal to distal margin of femora of all leg pairs). Despite a relatively wide range of variability in these characters, it may be helpful in identification of some species.
The dichotomous key divides
Some characters within the key are subject to variation in some species. For instance,
Most
The “Main morphological diagnostic characters of larvae” were described based on late-instar larvae (fully-grown larvae). The order of characters is not concise in relation to all species; it always starts with the most prominent character for a given species after which the value of subsequent characters for species identification diminishes. For each species included in the guide, geographical and altitudinal distribution with frequency of sampling sites is provided. The construction of distribution maps was based on published records (Table
Records of
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* without exact localisation, not included in distribution maps. ** doubtful record not included in distribution maps. *** unpublished record included in the distribution map.
1 | Medial hypodermal femur spots present (e.g., Fig. |
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– | Coloration pattern on abdominal sterna present (Figs |
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– | Coloration pattern on abdominal sterna absent (Figs |
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2 | Medial hypodermal femur spots absent (e.g., Fig. |
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– | Coloration pattern on abdominal sterna present (Figs |
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– | Coloration pattern on abdominal sterna absent (e.g., Figs |
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1 | Abdominal sterna II–VI with a pair of oblique stripes (Figs |
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– | Abdominal sterna II–V (VI) with a pair of triangular spots (Fig. |
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2 | Stripes on abdominal sterna II–VI widened anteriorly (Fig. |
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– | Stripes on abdominal sterna II–VI not widened anteriorly (Figs |
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3 | Abdominal terga V–VII with crown-like medial macula (Fig. |
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– | Abdominal terga V–VII with stripe-like medial macula and a pair of distinct antero-lateral stripes (Fig. |
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1 | Medial hypodermal femur spots distinctly elongated (Fig. |
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– | Medial hypodermal femur spots rounded, not distinctly elongated, gill plates III with well-developed projection; setae on abdominal terga hair-like (e.g., Fig. |
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2 | Abdominal terga V–VII with stripe-like medial macula and lateral stripes extended dorso-posteriorly (Fig. |
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– | Abdominal terga V–VII with more or less triangular or T-shaped medial macula, lateral stripes not extended dorso-posteriorly (Fig. |
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1 | Setae on abdominal terga wide at base |
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– | Setae on abdominal terga hair-like |
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2 | Abdominal terga II–IX with a pair of postero-medial protuberances (Fig. |
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– | Abdominal terga without postero-medial protuberances; terga V–VII with well-defined triangular maculae (Fig. |
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3 | Postero-lateral projections on tergum X distinct (Fig. |
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– | Postero-lateral projections on tergum X absent or indistinct, coloration pattern of abdominal sterna different |
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4 | Abdominal sterna II–VI yellowish, with a pair of black oblique stripes or brownish rounded medial macula |
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– | All or at least abdominal sterna VIII–IX intensively red (Fig. |
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5 | Abdominal sterna II–VI with a pair of black oblique stripes (Fig. |
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– | Abdominal sterna II–VI with brownish rounded medial macula (Fig. |
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6 | Gill plate VII wide (Figs |
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– | Gill plates VII narrow (Figs |
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1 | Postero-lateral projections on tergum X present (Fig. |
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– | Postero-lateral projections on tergum X absent (Figs |
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2 | Abdominal terga V–VII with narrowed triangular medial macula and a pair of anterolateral spots (Fig. |
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– | Abdominal terga V–VII with well-defined triangular medial maculae, without a pair of anterolateral spots (Fig. |
Azerbaijan, The Nakhchivan Autonomous Republic, a stream in the vicinity of the upper Sakarsu River (3000 m a.s.l.).
Georgia, south-western Russia, Azerbaijan, Armenia, eastern Turkey (Fig.
Larvae inhabit small streams and rivers at middle and high altitude, most frequently found above 1000 m a.s.l. Altitudinal range of sampling sites 496–2474 m a.s.l. (Fig.
(i) abdominal sterna II–VI with a pair of oblique stripes; nerve ganglia often with stripes or spots (Fig.
Geographical (left) and vertical (right) distribution of
Azerbaijan, Nakchivan Autonomous Republic, Giljan-tshaj (Gilljak) (2000–2100 m a.s.l.).
Georgia, south-western Russia, Azerbaijan, Armenia, Turkey, northern Iran (Fig.
Larvae inhabit streams and rivers of various sizes, from larger braided low altitude rivers to small streams at high altitude. Altitudinal range of sampling sites -6–2453 m a.s.l. (Fig.
(i) abdominal terga II–IV with triangular medial macula and terga V–VII with T shaped medial macula (Fig.
Geographical (left) and vertical (right) distribution of
Russia, Krasnodar krai, western Caucasus, Sochi River (20 km above Sochi; 800 m a.s.l.).
Georgia, south-western Russia, Azerbaijan, Armenia, Turkey (Fig.
Larvae inhabit streams and rivers of various sizes, from larger braided low-altitude rivers to small streams at high altitude. Altitudinal range of sampling sites 6–2474 m a.s.l. (Fig.
(i) shape of head in male and female oval, trapezoidal (Fig.
Geographical (left) and vertical (right) distribution of
Georgia, Mtskheta-Mtianeti Region, Kistinka (= Khde, Khdistkhali) River (along the Georgian Military Road, 1300 m a.s.l.).
Georgia, south-western Russia, Turkey, Cyprus Island, northern Iraq, northern Iran (Fig.
Larvae inhabit small streams and rivers at low to high altitude. Altitudinal range of sampling sites 280–2100 m a.s.l. (Fig.
(i) abdominal sterna II–VI with a pair of triangular spots; nerve ganglia often with spots (Fig.
Geographical (left) and vertical (right) distribution of
Russia, The Karachay-Cherkess Republic, western Greater Caucasus, Teberda (Glacier Alibek – stream, 1800–1900 m a.s.l.).
Georgia, south-western Russia. Species endemic to the Greater Caucasus (Fig.
Larvae inhabit small streams and rivers at middle and high altitude in the western and central Greater Caucasus. Altitudinal range of sampling sites 570–2580 m a.s.l (Fig.
(i) abdominal terga V–VII with narrow stripe-like medial macula; widened on terga VIII–IX (Fig.
Geographical (left) and vertical (right) distribution of
Russia, The Karachay-Cherkess Republic, western Greater Caucasus, Teberda (Glacier Alibek – stream, 1800–1900 m a.s.l.).
Georgia, south-western Russia. Species endemic to the Greater Caucasus (Fig.
Larvae inhabit small streams and rivers at middle and high altitudes in the western and central Greater Caucasus. Frequently found above 1000 m a.s.l. Altitudinal range of sampling sites 426–1900 m a.s.l. (Fig.
(i) abdominal terga V–VII with well-defined triangular medial maculae (Fig.
Geographical (left) and vertical (right) distribution of
Iran, Tehran Province, river in the Darban-Tal (Darban Valley), 2100 m a.s.l.
Northern Iran. Species endemic to the Alborz Mountains (Fig.
Larvae inhabit streams at altitudes above 2000 m a.s.l. in the western and central Alborz. Altitudinal range of sampling sites 2020–2440 m a.s.l. (Fig.
(i) abdominal sterna II–VI with a pair of oblique stripes; nerve ganglia often with stripes or spots (Fig.
Geographical (left) and vertical (right) distribution of
Russia, the Kabardino-Balkarian Republic, central Greater Caucasus, right tributary of Dongoserun (Donguz-Orun-Baksan) River (2100 m a.s.l.).
Georgia, south-western Russia. Species endemic to the Greater Caucasus (Fig.
Larvae inhabit small streams and rivers at middle and high altitude in the western and central Greater Caucasus. Altitudinal range of sampling sites 760–2580 m a.s.l. (Fig.
(i) abdominal terga V–VII with narrowed triangular medial macula and a pair of anterolateral spots (Fig.
Geographical (left) and vertical (right) distribution of
Georgia, Mtskheta-Mtianeti Region, central Greater Caucasus, tributary of Aragvi River, 3 km above Pasanauri (1400–1500 m a.s.l.).
Georgia. Species endemic to the Greater Caucasus (Fig.
Larvae inhabit small streams and rivers at middle altitude in the central Greater Caucasus. Altitudinal range of sampling sites 903–1193 m a.s.l. (Fig.
(i) femora with elongated medial hypodermal spot (Fig.
Geographical (left) and vertical (right) distribution of
Greece, Samos Island, stream east of Pirgos,
Known only from few sites in Samos Island (Fig.
Larvae inhabit small forested streams at 128–440 m a.s.l. (Fig.
(i) abdominal terga V–VII with T-shaped medial macula (Fig.
Geographical (left) and vertical (right) distribution of
Georgia, Autonomous Republic of Adjara, vicinity of Chakhati village, Kintrishi River;
Georgia, north-eastern Turkey, Armenia, south-western Russia (Fig.
Larvae inhabit streams and rivers of different sizes, from to middle-sized rivers at low altitude to small streams at high altitudes. Altitudinal range of sampling sites 40–1804 m a.s.l. (Fig.
(i) abdominal terga II–IX with paired postero-medial protuberances (Fig.
Geographical (left) and vertical (right) distribution of
Turkey, Artvin Province, Camili Village, Merata Plateau, unnamed mountain stream;
North-eastern Turkey, Georgia (Fig.
Larvae inhabit small streams at middle and high altitudes. Altitudinal range of sampling sites 928–2388 m a.s.l. (Fig.
(i) femora with medial hypodermal spot (Fig.
Geographical (left) and vertical (right) distribution of
Iran, Mazandaran Province, Panjab village, unnamed brook (left tributary of Haraz River);
Northern Iran. Species endemic to the Alborz Mountains (Fig.
Larvae inhabit small rivers at middle and high altitude in the central Alborz. Altitudinal range of sampling sites 750–2438 m a.s.l. (Fig.
(i) abdominal terga as on Fig.
The type series is currently deposited in
Geographical (left) and vertical (right) distribution of
Iran, Golestan Province, Shirinabad village, unnamed river;
Northern Iran. Known only from three sites in the eastern Alborz (Fig.
Larvae inhabit streams at middle altitude, 740–1450 m a.s.l. (Fig.
(i) abdominal terga V–VII with triangular or T-shaped medial macula (Fig.
Geographical (left) and vertical (right) distribution of
Iran, Chaharmahal and Bakhtiari Province, Dimeh village, Chehme-Dimeh River,
South-western Iran. Known only from few sites in the central Zagros (Fig.
Larvae inhabit streams and rivers at high altitude, 1721–2402 m a.s.l. (Fig.
(i) abdominal sterna II–VI with a pair of anteriorly widened oblique stripes (Fig.
This species was described based on larvae collected from Zagros Mts. (
Geographical (left) and vertical (right) distribution of
This contribution represents the first complete source of information for the routine identification of the larvae of all fifteen
All species of
We are grateful to colleagues, who collected mayflies in the field and provided us with material (A. Abdoli, S. Bagheri, N. Kazancı, P. Manko, A.V. Martynov, V.V. Martynov, J. Imanpour Namin, F. Nejat, J. Oboňa, D. Öztürk, M. Pallmann, D.M. Palatov and G. Türkmen). We thank Arnold H. Staniczek (State Museum of Natural History Stuttgart) for providing material and allowing us to study the type specimens from the Dietrich Braasch collection, and P. Klimeš (Biology Centre, CAS) for access to photographic equipment. This research was conducted with institutional support of the Institute of Entomology (Biology Centre, CAS) for LH, PS and RJG and the Grant Agency of University of South Bohemia: GAJU 152/2016/P provided for LH.