Eurylophella korneyevi, Martynov, Alexander V., Palatov, Dmitry M. & Godunko, Roman J., 2015

Martynov, Alexander V., Palatov, Dmitry M. & Godunko, Roman J., 2015, The larvae of West Palaearctic Eurylophella Tiensuu, 1935 (Ephemeroptera: Ephemerellidae), with description of a new species from Georgia, Zootaxa 3904 (1), pp. 123-143 : 125-132

Eurylophella korneyevi sp. nov.

Figures 1, 2, 4–27 , 38 , 54

Material. HOLOTYPE: female larva, GEORGIA, Autonomous Republic of Adzharia, territory of Kobulety town, Kintrishi River (near creek), current velocity—0,2– 1 m /s, width of the river— 10–15 m, water temperature—12°C, 41º48’14’’N 41º46’33’’E, 29.01.2013, larvae were collected on roots and grass near waterside, Palatov D.M. leg. PARATYPES: 18 larvae (two mounted in Canada balsam—slide № 541, 542—in Martynov A. collection at NMNH NASU), same locality as holotype, 29.01.2013, Palatov D.M. leg.

Etymology. The new species is named in honor of Dr.Sc., Ph.D. Valery A. Korneyev (I.I. Schmalhausen Institute of Zoology National Academy of Sciences of Ukraine), dissertation scientific adviser of the first author and colleague of all authors.

Diagnosis. Occipital tubercles small in male and female. Submedian tubercles on abdominal segment VII widely spaced, average SMT7 = 1.01 (range 0.9–1.1); abdominal segments V–VII somewhat reduced in length, average MLT2:7 = 1.30 (1.21–1.43); posterolateral projections on abdominal segment IX relatively long, average PLP9 = 0.61 (range 0.53–0.69); body length of full-grown larva 9.7 to 12.5 mm; submedian tubercles subparallel or slightly divergent from abdominal segments II to VII; tubercles on segments I–III middle sized, wide and blunt in dorsal view, arched and wide is lateral view; on segments VIII–IX developed and pointed. Dorsal subdivisions of lower lamella of gill IV somewhat reduced in number (dorsal subdivisions—4–6, ventral—6–9) and main part of them reduced in size (to about half the size of ventral subdivision); often one or two dorsal subdivisions are not reduced in size. Known only from Caucasus Mts.

Description. Mature larva. Size: body length 9.7–12.5 mm; cerci and paracercus length 8–10 mm. General body colour yellowish-brown to brown. Abdominal tergites and sternites with well visible pattern which consist of dark brown, black and yellow spots and lines ( Figs 5 –9).

Head. Yellowish-brown to brown, with unsharp light (yellowish-brown) pattern consisting of spots of different size. Main number of spots located between eyes and under the antennae, ocelli and eyes, where they may merge in lines. Head trapezoid; widest part at the level of eyes ( Figs 5–7 ). Antennae yellow to light brown, paler than head. Surface of head without long hair-like setae, densely covered by sockets, with solitary very rare short fine setae. Occipital tubercles very small and knobs shaped ( Figs 19, 20 ).

Mouthparts: Labrum wide, slightly concave in central part of outer margin; densely covered by whip-shaped long setae; angles strongly flattened. Mandibles with four teeth and group of long setae under the molae ( Figs 13, 14 ), 3–4 times more numerous on the right mandible. Maxillae typical for the genus, without maxillary palps ( Figs 15, 16 ). Group of 7–9 long setae situated on the inner side of the maxillae. Hypopharynx without specific features, with long setae on the apexes of superlinguae and short setae at lingua ( Fig. 17 ). Segments I and II of labial palps with irregular row of whip-shaped long setae on inner margin; third segment relatively slender, conical, bluntly pointed apically, with short stout setae on apex ( Figs 18 , 38 ); segment III length/width ratio: 1.58−1.93. Glossae and paraglossae short and robust, densely covered by whip-shaped long setae.

Thorax. Pronotum yellowish-brown to brown with numerous yellow to yellowish-brown spots; few relatively small dark-brown spots situated laterally ( Figs 5–7 ). Pronotum rectangular, with slightly concave lateral margins. Mesonotum yellowish-brown to brown, with numerous yellow-brown spots of different sizes (largest spots located at the anterior angles). Few relatively small dark-brown spots present on mesothorax laterally ( Fig 5–7 ). Surface of thorax densely covered by sockets, some of them with solitary short fine setae. Long setae on thorax absent.

Legs yellowish; colour pattern with several large and much smaller yellow-brown to light-brown maculae ( Figs 5–7 , 21 ). Tarsal claws with 9–11 teeth. Tarsi yellow, with distinct light-brown bands in basal and apical parts. Tibiae yellow, with light-brown smudges (sometimes bands) centrally, and additional shapeless spot or band near joints with femora (these spots usually fused). Femora with elongated spot basally and band with diffused borders below the widest part (the last one usually with roundish yellow spots).

Femora of legs insignificantly broadened: FWL1 = 0.42, range 0.37–0.45; FWL2 = 0.39, range 0.37–0.43.

Stout setae on dorsal surface of mid-femora of various types, the most common constituted by elongated and bluntly pointed apically setae, and setae with rounded tips and parallel margins ( Fig. 22 ); outer margin of femora with not dense row of stout setae and irregular row of short and middle sized hair-like setae ( Fig. 21 ); inner margin of femora with irregular row of stout setae which reaches end of broadened part of femora and irregular row of short and middle sized hair-like setae. Stout setae on dorsal surface of femora of forelegs longer than on other legs.

Abdomen. Tergites yellow-brown to light-brown, with yellow pattern typical for the genus Eurylophella ( Figs 5 –9). Light (occasionally poorly visible) median stripe on tergites between submedian tubercles. Mainly three pairs of blackish-brown smudges present on tergites I–IV: one above the submedian tubercles and two laterally from them (near posterior margin of tergites and on line of tergites’ transversal axis). Tergites V–X with brown smudges near submedian tubercles. One pair of long brown angular lateral lines situated on tergite IX 8–12. Abdomen of E. korneyevi sp. nov., holotype (8) and paratypes (9–12): 8, 9.—dorsal view; 10, 11.—ventral view; 12.—gills of tergite IV; scale bar = 1 mm.

centrally. Numerous small roundish spots on all tergites. Upper parts of posterolateral projections yellow; the tips of posterolateral projections on tergites IV–IX darkened. Surface of tergites under the gills yellow. Occasionally, abdominal tergites pale, with unclear brown smudges and contrast black maculae (rarely without the last one) ( Figs 7 , 9).

Abdomen with shortened segments V −VII and elongated segment IX (Figs 8, 9, 27). MLT2:7 = 1.30, range 1.21–1.43.

Submedian tubercles: middle sized, distinctly broad, with rounded apexes on tergites I–IV; larger, broad, with pointed apexes on tergites V–VII; distinctly pointed, small, but clearly visible on tergites VIII–X ( Figs 23, 24 ). SMT2 = 0.88, range 0.74–0.93; SMT7 = 1.01, range 0.90–1.10; TL7 = 0.3, range 0.21–0.38; ITD4:7 = 1.12, range 1.04–1.26; ITD2:7 = 1.13, range 1.00–1.22. Rows of submedian tubercles on abdominal tergites II to VII subparallel or slightly divergent. Tubercles of tergites I–IV arched and distinctly wide in lateral view ( Fig. 26 ).

Posterolateral projections of tergite II relatively well developed: PLP2 = 0.12, range 0.10–0.13; of tergite IX—medium sized: PLP9 = 0.61, range 0.53–0.69.

Stout setae on abdominal tergites of various types, with several well distinguishable groups on different parts of tergites: (i) small, parallel sided, rounded apically—at submedian tubercles of tergites II–IV and neighbouring fields ( Fig. 27 : 2); (ii) middle and long, parallel sided, rounder or bluntly pointed apically—at surfaces of posterolateral projections of tergites V–VIII ( Fig. 27 : 5); middle and long, parallel sided, rounded apically—at submedian tubercles of tergites V–VII and neighbouring fields ( Fig. 27 : 4); small and middle, parallel sided, rounded apically—at tergite IX ( Fig. 27 : 10, 11); elongated, parallel sided, rounded or bluntly pointed on tergite VIII surface (dominant types) ( Fig. 27 : 7, 8); rows of middle sized stout setae, with subparallel or slightly divergent margins and rounded apically stout setae, alternating with middle hair-like setae at posterior margin of posterolateral projections of tergite VIII ( Fig. 27 : 9, 9a). In all cases density of setae at submedian tubercles of tergites lower than at neighbouring fields.

Posterior margin of tergites VIII–X medially with one regular row of narrow, slender, pointed apically teeth; one or two irregular subapical rows of small pointed teeth situated along posterior margin of these tergites ( Fig. 27 : 12).

Sternites yellowish: I–VIII (Fig. 10) with three pairs of blackish-brown smudges of different size (some smudges hardly visible at lighter coloured specimens, see e.g. Fig. 11); sternite IX (in male and female) paler than other ones. All surface of sternites I–X covered by middle sized fine setae.

Gills on segment I consisting of a single filament; gills on segments IV–VII bilamellate: the ventral lamella bifurcate laterally. Gills on segment IV oval, yellowish-brown, with numerous roundish yellow spots of different size, covering large part of gills V–VII (Figs 8, 9, 12). Dorsal subdivisions of lower lamella of gills IV somewhat reduced in number (dorsal subdivisions—4–6, ventral—6–9) and main part of them reduced in size (to about half the size of ventral subdivision). Often one or two dorsal subdivisions not reduced in size ( Fig. 54 ).

Cerci and paracercus yellowish to yellowish-brown, of the same length. Two or three brown bands presented on basal part of filaments, other part of filaments with alternating pairs of yellow and light-brown segments. Most part of segments (except about twenty proximal segments) with regular rows of long hair-like setae on lateral surface. Basal half of segments with rings of stout setae with subparallel margins and rounded tips ( Fig. 25 ).

Figures

FIGURE 27. Main chaetotaxy features of Eurylophella korneyevi sp. nov. abdomen, larva, paratype (scheme): numeric designations are decoded in the material and methods chapter; d—dominant types of setae.

FIGURES 1 – 4. Stout setae of body surface of E. korneyevi sp. nov. (1, 2, 4) and E. karelica (3): 1. — stout seta of surface of tergite VII; 2. — stout setae on surface of posterolateral projection of tergite VII; 3. — stout seta of surface of tergite VIII; 4. — stout setae on lateral margin of posterolateral projection of tergite IX; scale bar = 10 µm.

FIGURES 5 – 7. Colour pattern of E. korneyevi sp. nov. larvae, holotype (5) and paratypes (6, 7): 5. — male, immature; 6. — female, immature; 7. — male, immature; scale bar = 1 mm.

FIGURES 13 – 18. Mouthparts of Eurylophella korneyevi sp. nov., paratype: 13, 14. — mandibles, scale bar = 100 µm; 15. — maxilla, scale bar = 100 µm; 16. — maxilla, apical part, scale bar = 10 µm; 17. — hypopharynx, scale bar = 100 µm; 18. — third segment of labial palp, scale bar = 10 µm.

FIGURES 19 – 26. Eurylophella korneyevi sp. nov., larvae, paratypes: 19. — occipital tubercles, female; 20. — occipital tubercles, male; 21. — middle leg; 22. — stout setae on surface of femur; 23. — submedian tubercles of abdominal tergites, dorsal view; 24. — submedian tubercles of abdominal tergite X, dorsal view, enlarged; 25. — stout setae of caudal filaments (basal part); 26. — submedian tubercles of abdominal I – IV tergites, lateral view. Roman numerals indicate tergite segments; d—dominant types of stout setae.

FIGURES 34 – 42. Larvae of Eurylophella korneyevi sp. nov. (38), E. iberica (34, 36, 39, 41) and E. karelica (35, 37, 40, 42): 34, 35. — submedian tubercles of abdominal tergites, dorsal view; 36, 37 — submedian tubercles of abdominal tergite X, dorsal view, enlarged; 38 – 40. — third segment of labial palp; 41, 42. — submedian tubercles of abdominal I – IV tergites, lateral view. Roman numerals indicate tergite segments.

FIGURES 54 – 56. Left gill on segment IV, lateral view: 54. — Eurylophella korneyevi sp. nov.; 55. — E. iberica; 56. — E. karelica.