Ecdyonurus (Helvetoraeticus) adjaricus, Kluge, Nikita J., Godunko, Roman J. & Apanaskevich, Dmitry A., 2013

Kluge, Nikita J., Godunko, Roman J. & Apanaskevich, Dmitry A., 2013, Mayflies of the Caucasus Mountains. II. Description of the first representative of the subgenus Helvetoraeticus Bauernfeind & Soldán, 2012 (Heptageniidae: Ecdyonurus), Zootaxa 3608 (1), pp. 51-66 : 52-65

Ecdyonurus (Helvetoraeticus) adjaricus sp. nov.

Figures 1–41

= Ecdyonurus /fg 2 sp. H5: Kluge 2004: 176.

Types. HOLOTYPE: male imago (dried pinned specimen; right fore and hind wings, forelegs, parts of middle and hind legs, and cerci on slide), GEORGIA, Autonomous Republic of Adjara, Kobuleti District, Kintrishi State Nature Reserve (KSNR), meadow near Zeraboseli farm, middle part of Kintrishi River, approximately 41Ο43,592’N 41Ο49,096’E, 480 m a.s.l., 28.vi.1974, leg. A. Zaguliaev.

PARATYPES: female imago (reared from larva, with larval and subimaginal skins preserved), same locality as holotype, 27−31.vii.1997, leg. D. Apanaskevich; 3 mature larvae (1 female, 2 males), ibid, 27−31.vii.1997, leg. D. Apanaskevich; 4 larvae, Autonomous Republic of Adjara, Kobuleti District, 3 km downstream of Zeraboseli farm, border of KSNR near bridge, 41Ο45,739’N 41Ο58,582’E, 325 m a.s.l., 18.viii.2009, leg. R.J. Godunko, T. Soldán and P. Sroka; 1 larva, Kobuleti District, Chakhati village (centre), Kintrishi River, 41Ο48,120’N 41Ο55,545’E, 140 m a.s.l., 18.viii.2009, leg. R.J. Godunko, T. Soldán and P. Sroka; 1 larva, Kobuleti District, Khala village, Kemerkobis stream (bridge 100 m upstream from mouth), 41Ο42,226’N 41Ο47,525’E, 67 m a.s.l., 18.viii.2009, leg. P. Sroka; 3 larvae, Kobuleti District, Khala village, Chakvistskhali River (mouth of Kemerkobis stream), 41Ο42,226’N 41Ο47,455’E, 60 m a.s.l., 19.viii.2009, leg. R.J. Godunko; 14 larvae (6 of them were mounted on slides), Kobuleti District, 3 km upstream at Chakhati village, Kintrishi River, 41Ο46,266’N 41Ο58,325’E, 275, m a.s.l., 31.vii.2010, leg. R.J. Godunko and N.O. Godunko; 5 larvae, Autonomous Republic of Adjara, Khelvachauri District, Tskhemlara [Tamara’] bridge near Chikuneti village, Machakhlistskali River, 41Ο30,424’N 41Ο49,215’E, 195 m a.s.l., 20.viii.2009, leg. P. Sroka; 11 larvae, Khelvachauri District, 200 m downstream at Tskhemlara [Tamara’] bridge near Chikuneti village, small stream (left side tributary of Machakhlistskali River), 41Ο30,345’ N 41 49 Ο02,42’E, 185 m a.s.l., 20.viii.2009, leg. R.J. Godunko and P. Sroka.

Male imago (dried pinned specimen). Size: body length: 15.5 mm; forewings length: 17.0 mm; cerci lost.

General body color distinctly dark, reddish-brown; few whitish spots on lateral sides of mesonotum. Head dirty brown to reddish-brown. Antennae blackish-brown, slightly paler distally. Ocelli dirty yellow apically. Eyes grayish, contiguous dorsally, with relatively narrow dark band basally.

Thorax dark brown to reddish-brown, slightly paler ventrally. Forewings hyaline with yellowish area in basal part of wing, in anal and cubital fields, and between C and RA; C and Sc dark brown, other veins brown; pterostigmatic area opaque, dirty yellow, with 6 simple and 7−8 branched veins. Hind wings entirely yellowish; venation brown, darker distally. Forelegs distinctly darker than middle and hind ones, brown to reddish-brown; forefemora only slightly darker than tibiae and tarsi. Middle and hind legs brown; tarsi slightly darker than femora and tibiae. No maculation on femora surface.

Abdomen dark brown to reddish-brown, sterna slightly paler. Lateral sides of terga II −VIII with roundish or triangular spots surrounded with an indistinct light L -shape marking typical for Helvetoraeticus species. Cerci dark brown.

Penis lobes yellowish-brown to brown. In dorsal and ventral view outline of penis lobes broadly rounded, not expanded laterally; lobes contiguous nearly over entire length ( Fig. 1 ). Apical sclerite relatively massive and short, slightly curved, only slightly expanded laterally and bluntly pointed at apex; lack of conspicuous denticulation at medio-internal portion; several small spines at external margin near tip of titillators; apex of sclerite not projecting above the lobes; only a slight projection at inner border. Lateral sclerite not broad, relatively straight, with subparallel anterior and posterior margins. Basal sclerite relatively massive, with 2–3 small spines only, without conspicuous teeth. Penis stem without a hump. Titillators brown. Styliger intensively brown, with two distinct, slightly curved protuberances near gonostyli bases; gonostyli slightly darker; segment II without any hump at inner margin basally ( Fig. 2 ).

Female imago. Size: body length: 15.0 mm; forewings length: 20.0 mm; cerci length: 13.0 mm.

General color of body similar to that in male imago, slightly paler; thoraxal pleurae with whitish blotches. Eyes with relatively narrow dark band basally. Fore and hind wings hyaline and transparent, uncolored; venation brown, darker distally. Legs light brown to brown, forelegs slightly paler. Abdominal pleurae with an indistinct light L - shape pattern. Cerci brown. Subgenital plate relatively wide; posterior margin slightly rounded. Subanal plate bluntly pointed apically.

Female subimago. Measurements and body color similar to those in female imago; thorax and abdomen slightly paler. Forewings relatively dark, with well visible pattern formed by transversal grayish bands (zigzag type).

Male subimago. Unknown.

Mature larva. Size: body length: 12.0−16.0 mm; cerci length: 9.0− 12.5 mm.

General body color yellowish-olive, brownish-olive to brown.

Head yellowish-olive to yellowish-brown with apparent light pattern, consisting of three blotches near fore margin of ocelli, and pair of spots near antennal bases; two small blotches near anterior margin of head; further large diffuse light spots situated laterally along posterior margin of head ( Figs. 3, 5 , 6, 8 ). Head capsule rounded anteriorly. Antennae with brown scape and pedicel; flagellum yellowish-white. Eyes and ocelli black.

Labrum relatively narrow with slightly curved and short lateral lobes; ratio of total labrum width to its width at base 2.3/1; 8−11 relatively slender bristles arranged in a single row on ventral side of labrum ( Fig. 17 ), diverging laterally into two irregular rows. Maxillae (n = 12): number of comb-shaped bristles (N_CBS) = 24–27 (mainly 26−27); number of teeth on 5th comb-shaped bristle (N_TCB5) = 11–14 (mainly 11–12); number of setae on inner side of first segment of maxillary palps (N_PLP)> 10; number of setae on outer margin of first segment of maxillary palps (N_PLS) = 22–38; number of hairs on dorsal upper side of galea-lacinia (N_DOR)> 15. Glossae stretched laterally, relatively widely spaced; glossae and paraglossae massive ( Fig. 16 ). Superlinguae with pilosity typical for Helvetoraeticus (only few setae at tip).

Pronotum yellowish-olive to light brown with several light spots centrally and laterally; lateral projections yellow to yellowish-white ( Figs. 5 , 6 ). Pronotum slightly extended laterally. Lateral projection large and long, relatively straight, only slightly asymmetrical, oriented parallel to body axis ( Figs. 3, 5 , 6, 8 , 13, 14 ), or slightly outwards ( Fig. 32 ); apex of lateral projection bluntly pointed; width/length ratio of semipronotum to caudal portion of projection is 1.95–2.30; length of caudal portion of projection is approximately half of total projection length.

Meso- and metanotum yellowish-olive to light brown; mesonotum with longitudinal light lines and spots laterally from median longitudinal suture, interrupted by pale areas near fore and hind margins.

Legs yellowish-olive and light brown to brown. Trochanters with 2 (rarely 3) irregular rows of bluntly pointed and slender spatulate bristles ( Figs. 24, 25 ). Femora long and relatively slender; length/width ratio of metafemora is 2.75−3.35 (mean 3.0, σ = 0.21; n = 8); widest part of metafemur at its midlength. Dorsally femora with large yellowish-olive to light brown spots on yellowish to yellowish-white background; uniformly yellowish-white to whitish ventrally (general color pattern of dorsal side of femora as illustrated by Godunko & Kłonowska-Olejnik 2004: 17, fig. 10; 2008: 812, fig. 33). Dense rows of sharply pointed bristles at inner margin of femora ( Fig. 19 ); outer margin of femur with row of long whip-like setae and dense rows of sharply pointed bristles ( Figs. 18 , 26, 27 ); same type of sharply pointed bristles at dorsal surface of femora (centrally and distally), occasionally more blunt in proximal part ( Figs. 20, 21 , 26, 27 ); a row of short pointed bristles on ventral side of posterior border of femora ( Fig. 27 ). Tibiae yellowish-brown, with well visible darker smudge in centrally; dorsal surface with row of spatulate bristles ( Figs. 28, 29 ). Tarsi brownish, with paler smudge centrally, indistinctly darker apically; sparse row of slender spatulate bristles at dorsal surface ( Fig. 30 ). Claw brown with 2 denticles ( Fig. 31 ).

Abdominal terga with pronounced yellowish-brown to dark brown pattern and yellowish background ( Figs. 3, 4 , 7, 8 ): tergum I relatively pale, with broad diffuse spot medially and a pair of spots laterally; terga II and III with a pair of spots medially, and a pair of spots laterally; terga IV and V with V- (or U-) shaped spot medially, and a pair of broad spots laterally (occasionally lateral spots fused with central spot at tergum V); tergum VI with U- (or V-) shaped spot medially (consisting of three more or less separated small spots); terga VII and VIII with broad Vshaped spot medially, turning into light strip stretching along posterior margin and lateral sides of segment; tergum IX with oval median spot, occasionally a pair of small spots laterally; tergum X generally unicolorous brown, occasionally with a pair of unclear longitudinal paler strokes medially. Abdominal sterna yellowish-white, distinct neural ganglion in segment VII (occasionally also in segments IV −VI); brown pattern of sterna mainly absent at segments I −V (occasionally VI); sterna VII −IX with pair of triangular brown spots laterally (in male) and with transversal brown stripes (in female); larval protogonostyli darker than abdominal sterna, light brown ( Figs. 9−12 ). Posterior margin of terga with dense row of stout spines pointed apically, alternating with smaller ones ( Figs. 15 , 22 ); surface of terga with numerous hairs. Posterolateral extensions of abdominal sterna well developed, distinctly long, sharpened apically and directed outwards at different angles to the body axis (except for expansions of sterna 7–8 directed parallely to the body axis) ( Figs. 9–12 ). Tergalii whitish to yellowish-gray, with distinct dark tracheae; tergalius I tongue-shaped, relatively long, moderately tapered distally, with plate longer than filamentous part ( Fig. 33 ); tergalius IV relatively slender, moderately asymmetrical, only with slightly conspicuously convex outer margin, distal margin not blunt, length/width ratio 2.25−2.60 (mean 2.41, σ = 0.19; n = 8) ( Fig. 34 ); tergalius VII broad and asymmetrical (widest part in 2/3 of tergalius length), without a tuft of tracheal filaments ( Fig. 35 ). Caudalii yellowish-brown, paler distally; each segment with sharply pointed bristles alternating with hairs ( Fig. 23 ).

Egg. Measurements: length 180−200 µm; width 130−155 µm.

Egg oval, slightly elongated ( Figs. 36, 37 ). Chorion covered with attachment structures — knob-terminated coiled threads (KCTs), numerous small rounded tubercles and delicate granules (granular ground matrix) ( Figs. 39, 40 ). Significant concentration of KCTs attachment structures (diameter 3.6−4.2 µm) at one egg pole, where distance between them is 0.3−2.4 µm ( Figs. 38, 39 ); other egg surface with rather sparsely KCTs attachment structures (distance between them 2.0−12.5 µm) ( Fig. 40 ). Small rounded tubercles (1.4−2.0 µm in diameter) are regularly distributed over whole chorion (0.1−3.0 µm distance between them) ( Figs. 39, 40 ). Two to three micropyles (13.3−15.0 µm in length; 8.5−10.2 µm in width) are visible in subequatorial region; micropylar rim thin, with a few sparsely distributed tubercles ( Fig. 41 ).

Etymology. The species is named after Adjara (autonomous republic within Georgia).

Affinities. Ecdyonurus adjaricus sp. nov. holds a clearly isolated position within Helvetoraeticus. The shape of the male imago penis lobes is typical for the subgenus; at the same time apical sclerites are expanded only slightly laterally (in contrast to other Helvetoraeticus species with markedly laterally stretched apical sclerites).

The larva of E. adjaricus sp. nov. can be recognized within the subgenus by the presence a well developed, relatively long posterolateral expansions of abdominal sterna; such size and shape of expansions is characteristic only for a few species of Ecdyonurus s. str. (Haybach 1999, figs. 2, 11). Additionally, several other characters of the larval mouthparts should be noted, e.g.: the single row of bristles on ventral side of labrum; a relatively small number of setae on the inner side of the first segment of the maxillary palps and the number of comb-shaped bristles on the maxilla (see Haybach 1999: 121, 137, 139).

The placement of E. adjaricus sp. nov. within the subgenus Helvetoraeticus can be confirmed by the absence of long and dense setae on the distal portions of the superlinguae of the hypopharynx of larva, and the general shape and structure of male imago genitalia.

The new species is very similar to E. krueperi (Stein, 1863) in both the adult and larval stages. These two species can be easily separated from other representatives of Helvetoraeticus by conspicuous wing coloration, especially that of the hind wings: yellowish in E. adjaricus sp. nov.; golden-brown in E. krueperi . At the same time, the hind wings of the new species are colored only in male imago, while they are colored in both sexes of E. krueperi (Puthz 1980: 349; Hefti & Tomka 1988: 332; Bauernfeind & Soldán 2012: 277). Other differences in male imagoes are the following: (1) penis lobes are broadly rounded and not expanded laterally, with apically touching lobes in E. adjaricus sp. nov. (outline of penis lobes are distinctly triangularly rounded, more or less separated apically in E. krueperi ; cf. Puthz 1980: 350, fig. 2; Hefti & Tomka 1988: 331−332, fig. 3; Hefti et al. 1989: 334, 338, fig. 10d; Bauernfeind & Soldán 2012: 277, 589, fig. 163); (2) apical sclerite only slightly curved, without conspicuous denticulation at medio-internal portion in E. adjaricus sp. nov. (apical sclerite strongly curved, with conspicuous denticulation medio-internally in E. krueperi ; cf. Puthz 1980: 350, figs. 4, 5; Bauernfeind & Soldán 2012: 277); (3) lateral sclerite not broad, relatively straight, with subparallel anterior and posterior margins, evenly sclerotized throughout its length in E. adjaricus sp. nov. (lateral sclerite almost square distally, broad, visibly sclerotized only in its central and distal part in E. krueperi ; cf. Bauernfeind & Soldán 2012: 277; for this reason some inconsistencies in the descriptions and figure were published by Hefti & Tomka 1988: 331−332, fig. 3 and Hefti et al. 1989: 334).

Larvae of E. adjaricus sp. nov. and E. krueperi possess a similar shape of the lateral projection of the pronotum (relatively straight, only slightly asymmetrical, bluntly pointed at the tip, oriented almost parallel to body axis), and similar shape of femoral bristles (sharply pointed in both species). Larva of E. adjaricus sp. nov. can be separated from E. krueperi by the following features: (i) row of bristles on ventral side of labrum medially singular (in contrast to double in E. krueperi ); (ii) glossae stretched laterally and relatively widely spaced (in contrast to elongated-quadrangular glossae in E. krueperi ; cf. Hefti & Tomka 1988: 330, fig. 1b; Hefti et al. 1989: 333, 335 [Table 1], fig. 6b); (iii) pointed bristles on ventral side of posterior border of femora (lack of this type of bristles in E. krueperi ; cf. Hefti et al. 1989: 333, 335 [Table 1]); (iv) posterolateral extensions of abdominal sterna well developed and distinctly long (in contrast to relatively short sternal expansions of E. krueperi , typical for all other Helvetoraeticus representatives); (v) shape of tergalius I (tongue-shaped, moderately tapered distally) and tergalius IV (relatively slender, moderately asymmetrical) (in contrast to broadly-shaped tergalius I and distinctly asymmetrical tergalius IV in E. krueperi ; cf. Jacob & Braasch 1984: 60, fig. 27; Hefti et al. 1989, 335 [Table 1]). Additional differences between E. adjaricus sp. nov. and E. krueperi are found in the color of thoracic and abdominal segments of adults and larvae, i.e. the new species is generally more darkly colored.

Only a few species of Helvetoraeticus (together with E. adjaricus sp. nov.) are characterized by a significant concentration of KCTs attachment structures on one egg pole, namely E. epeorides Demoulin, 1955 , E. krueperi , E. picteti (Meyer-Dür, 1864) , E. silvaegabretae Soldán & Godunko, 2006 and E. siveci Jacob & Braasch, 1984 (see summarized data in Bauernfeind & Soldán 2012).

We are confident that the male imago (holotype, not reared from larva) and larvae (as well as reared female imago) described here belong to the same species. This is strongly supported by the fact that all material was collected in the same region (distance between the outermost studied localities is 30−35 km; 2−5 km between localities where holotype and paratypes were collected) and during the same summer period. The male imago body color is similar to that of the female. However the hind wings are colored in male and colorless in female.

Distribution and biology. The known distribution of E. adjaricus sp. nov. is restricted to several rivers of south-western spurs of Meskheti [Adjar-Imereti] Range and Shavsheti Range within Georgia. In Meskheti Range all investigated rivers are located on northern slopes; Kintrishi and Chakvistskhali rivers flow directly into the Black Sea. The localities within the Machakhlistskali river-basin (a part of Chorokh [Çoruh] river-basin) are situated on south slopes near the Turkey border. All habitats are located in the lowest parts of this area within altitudes 60–480 m a.s.l. There is a high probability that the new species can be found in other tributaries of Chorokh [Çoruh] river-basin within Turkey (at least in rivers of Turkish part of Shavsheti Range, as well as rivers within Kaçkar Mountains [Kaçkar Daġları]). Information about distribution of Helvetoraeticus in Turkey have been earlier published by Kazancı (2001: 29, 50) and Tanatmış (2004: 235), as records of Ecdyonurus helveticus Eaton, 1883 from Ankara −Bolu −Eskişehir regions (most probably based on misidentification; see Bauernfeind & Soldán 2012: 276).

Larvae of our new species inhabit the rhithral zone, and they are found only in middle-sized rivers and in coldwater streams. Larvae were registered in epi- to metarhithralic sections, where they were presented in insignificant quantity. Like all other representatives of Helvetoraeticus, E. adjaricus sp. nov. is a lithoreophile; the majority of its larvae are found in shallow water over a stony river bed (with large or small stones). The new species is found in rivers up to 12−17 m wide, and in streams more than 1−1.5 m wide and up to 0.6 m deep ( Fig. 42 ). Larvae were recorded in current velocity range from 0.2 to 0.8 m /sec; water temperature in June −August is between 14 and 19°C.

Figures

FIGURE 42. Type locality of Ecdyonurus (Helvetoraeticus) adjaricus sp. nov. (Kintrishi River, upper part, 2 km downstream at the border of the Kintrishi State Nature Reserve, AR Adjara, Georgia).

FIGURES 1 – 2. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., male imago, holotype: 1, penis lobes, dorsally; 2, genitalia, ventrally.

FIGURES 3 – 5. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., larva, paratype, dorsally: 3, general view; 4, color pattern of mesonotum and abdominal terga; 5, head and thorax.

FIGURES 6 – 8. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., larva, paratype, dorsally: 6, head and thorax; 7, color pattern of abdominal terga; 8, general view.

FIGURES 9 – 12. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., larvae, paratypes, abdomen ventrally: male (9 − 11); female (12).

FIGURES 13 – 15. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., larva, dorsally: 13, 14, lateral projection of pronotum; 15, abdominal terga I − IV.

FIGURES 16 – 21. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., larva: 16, glossa and paraglossa of labium; 17, labrum, ventrally; 18, outer margin of metafemur; 19, inner margin of metafemur; 20, femoral setae (surface of metafemur, proximally); 21, femoral setae (surface of metafemur, centrally).

FIGURES 22 – 27. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., larva: 22, posterior margin of tergum IV; 23, surface of terminal filament (details); 24, 25, surface of trochanter; 26, surface of metafemur (proximally, dorsal view); 27, surface of metafemur (distally, dorsal view).

FIGURES 28 – 31. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., larva: 28, 29, surface of tibia (centrally, dorsal view); 30, surface of tarsus (centrally, dorsal view); 31, tarsal claw.

FIGURES 32 – 35. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., larva: 32, lateral projection of pronotum (dorsally); 33 − 35, tergalii shape (dorsally), roman numbers belongs to the respective tergalius pairs.

FIGURES 36 – 41. Ecdyonurus (Helvetoraeticus) adjaricus sp. nov., egg: 36, 37, general outline of the egg, scale bar = 10 μm; 38, 39, egg pole with cluster of large KCTs attachment structures, scale bar = 10 μm; 40, chorionic surface with tubercles and attachment structures (KCTs), scale bar = 1 μm; 41, micropyle, scale bar = 1 μm.