Stenelmis puberula (Kodada, 2004)

Čiamporová-Zaťovičová, Zuzana, Jr, Fedor Čiampor & Kodada, Ján, 2007, Stenelmis puberula Reitter (Coleoptera: Elmidae) - description of larva and its association with adults, using DNA sequences, Zootaxa 1661 (1), pp. 17-28 : 19-26

Description of the larva of Stenelmis puberula .

Habitus ( Fig. 1 ). Length 5.70–6.04 mm, greatest width 0.41–0.84 mm. Dorsal and ventral side subequal in colour, yellow to yellow-brown; head, prothorax, apex of ninth abdominal segment and marginal parts of all thoracic and abdominal segments darkened to brown; legs yellow, distal part of femur and proximal part of tibia darkened. Body elongate, sides subparallel, anteriorly and posteriorly slightly converging; moderately convex dorsally, almost flat ventrally, crescent-shaped in cross-section. Biforous spiracles present laterally on mesothorax and abdominal segments 1–8.

Integument subglabrous, shiny, with two types of setae present: long acuminate setae sparsely and regularly distributed on body in pairs ( Figs 25 , 39 ) and shorter tufted dense setae (mainly on granulated parts) ( Fig. 37 ).

Head ( Figs 2–4 , 18 ) oval in dorsal view, dorsoventrally flattened, prognathous, partially retracted into prothorax, feebly longer than wide; slender subacuminate tooth on anterior margin between base of antenna and clypeus present; frontoclypeal plate feebly grooved, epicranial plates and genae granulated, granules with tufted scales ( Figs 2, 3 ). Epicranial sutures well visible, coronal suture short, frontal sutures long, almost straight, extending to base of antennae, frontoclypeal suture present. Stemmata small, clustered into oval black spot. Gula about half as long as labium, microreticulate ( Fig. 4 ). Antenna ( Figs 5–7 ) three-segmented; scape widest, subapically with one distinctly long and few shorter tufted setae; pedicel slender, elongate, feebly constricted subapically, almost three times as long as scape; flagellum setiform, apex slightly widened, rounded, with two scale-like sensilla; sensorium subacuminate, slightly shorter than flagellum ( Fig. 7 ). Labrum short, more than twice as wide as long, rugose, with longer and shorter hairs and tufted scales in anterior half ( Figs 8, 9 ); anterior margin ventrally with serrate scales ( Fig. 11 ); tormae very short, straight, mesally oriented; epipharynx with moderately long, arched, mesally oriented forked scales ( Fig. 10 ). Clypeus wide, very short; frontoclypeal suture visible. Mandible ( Figs 12, 13 ) well developed, palmate, with three oblique subacuminate apical teeth; incisor area with long curved articulated setose process; mola absent; penicillus well developed, consisting of forked scales; outer margin smooth; ventral condyle rounded; ventral side transversally grooved along middle, with small spines near condyle. Maxilla ( Figs 14–18 ) slender; cardo small subtriangular, with moderately long branched seta ( Fig. 18 ); stipes elongate, smooth, only with one long sublateral seta ( Fig. 16 ) and three short, forked scales ( Figs 14, 15, 17 ); outer margin slightly convex; galea and lacinia equally long, flattened, apically with acuminate setae ( Fig. 17 ); maxillary palpus 4-segmented, about as long as lacinia, segments 1 and 2 shorter, 3 and 4 longer; apical sensory field of distal segment with one longer and several shorter peg-like sensilla ( Fig. 17 ). Labium elongate, slightly longer than stipes ( Figs 18, 19 ). Prementum very short, membranous; ligula glabrous with paired short, acuminate admedian sensilla. Postmentum undivided, glabrous, with few forked scales, small pegs and two long, acuminate lateral sensilla; basal portion of disc with spines; apical angles slightly excavate with elongate pegs ( Fig. 20 ); labial palpi 2- segmented ( Fig. 20 ); segment 1 subglobular; segment 2 peg-like with apical sensory field ( Fig. 21 ). Hypopharynx simple ( Fig. 22 ).

Thorax. Protergum slightly longer then wide, widest in posterior half; anterior margin feebly arcuate, bearing flat forked scales; posterior margin finely rugose ( Fig. 24 ); lateral sides slightly converging anteriad; sublaterally in anterior half with fine depressions (with rimmed setiferous pits) extending to lateral and anterior margin of protergum ( Fig. 23 ); anterior half of protergum with 4 pairs of long hair-like setae ( Fig. 25 ); posterior angles with microgranulated spots, each with central long fine seta ( Fig. 24 ); laterally from spots two additional pairs of setae. Meso- and metatergum wider than long, about half as long as protergum, both with: 1) microreticulate anterior part normally concealed by preceding segment; 2) posterior margin finely rugose; 3) two irregular microgranulate admedian spots with long central seta; 4) in anterior half of terga, each with central long fine seta, laterally from them two additional pairs of setae. Area along sagittal line of all thoracic segments slightly grooved. Posterior margin of meso- and metathorax with row of flat, distally forked scales. Venter of prothorax with: suture between epimeron and sternellum hardly visible; portion anterior to coxae shorter than posterior portion; medial acuminate projection of basisternum short. Venter of meso- and metathorax with large basisternum and distinct laterotergites; basisterna microreticulate in anterior half and glabrous in posterior half; portion behind coxae reduced, membranous ( Fig. 26 ). Legs well developed, fivesegmented, relatively long. Fore-legs shortest and robust ( Figs 27, 28 ), mid- and hind-legs slender, equal in shape ( Figs 32, 33 ). Each coxa large, elongate procoxa subtriangular, meso- and metacoxa arched. Trochanter (shortest segment) subtriangular, protrochanter twice, meso- and metatrochanter about three times shorter then femur, each with transversal line and few acuminate serrate scales. Femur elongate, subparallel, with acuminate, serrate scales mostly on inner and fine setae on outer side ( Fig. 29 ) and short tufted scales near apex ( Fig. 35 ). Tibia slightly longer than femur, with distinct acuminate, serrate scales on inner side and finer setae on outer side ( Fig. 30 ); proximal third of each tibia markedly widened, darkened ( Fig. 34 ). Tarsungulus long, slender, acuminate, slightly shorter than half length of tibia, moderately curved, with small, baso-ventral spines ( Fig. 31 ).

Abdomen with nine segments; anterior portion of segments (normally concealed by preceding segment) microreticulate ( Figs 38, 39 ); exposed portion with admedian microgranulate paired spots, centrally with long thin seta ( Fig. 25 ), sparsely distributed short tufted setae and few (2–3 pairs) of long setae ( Fig. 39 ), posterior margin of segments 1–8 and apex of ninth abdominal segment finely rugose ( Figs 39, 40 ), bearing row of flat, distally forked scales ( Fig. 36 ). Segments 1–8 simple, subrectangular in dorsal view, similar in shape, subequal in length, wider than long; distal margin with row of forked, flat scales ( Fig. 36 ). Segments 1–7 with distinct tergum, paired elongate pleura and subquadrate sternum ( Fig. 38 ); terga 1–5 with distinct sagittal line, area along line slightly grooved; segment 8 with all sclerites fused. Segment 9 trapezoidal, elongate, about 2.5 times as long as wide, tapering towards distal end. Apex darker then rest of tergum, emarginate, ending in two distinct lateral spinous processes ( Fig. 40 ); laterally from midline strongly depressed at both sides ( Figs 40, 41 ). Ninth segment bearing retractile tufts of filamentous tracheal anal gills. Ventral operculum not reaching apex of segment 9; pentagonal, slightly longer then wide, tapering in posterior third, anterior margin straight, posterior margin with tufted setae, distal half with strong rhombic depression; apical opercular claws well developed, long and slender ( Fig. 42 ).

Material examined. Larvae (CZB, CCB, CKB, NMW, SNM): SLOVAKIA: 1 ex: Udava stream, Hostovické lúky, Ni ž ná Jablonka env., Nízke Beskydy Mts., 49°07'48''N, 22°07'21''E, 329m a.s.l., 23. IV. 2003 ; 17 exs: Svetlička stream, Svetlice env., Nízke Beskydy Mts., 49°09'58''N, 22°01'33''E, 300m a.s.l., 24. IV. 2003 ; 28 exs: Výrava stream, Svetlice env., Nízke Beskydy Mts., 49°09'35''N, 22°00'54''E, 293m a.s.l., 24. IV. 2003 ; 44 exs: Svetlička stream, Svetlice env., Nízke Beskydy Mts., 49°09'58''N, 22°01'33''E, 300m a.s.l., 18. X. 2003 ; 1 ex: Ulička stream, Kolbasov env., Poloniny, 21. VII. 2005 , Č iampor & Za ť ovičová lgt.; 54 exs: Svetlička stream, Svetlice env., Nízke Beskydy Mts., 49°09'58''N, 22°01'33''E, 300m a.s.l., 22. VII. 2005 , Č iampor & Za ť ovičová lgt.; 1 ex: Udava stream, Ni ž ná Jablonka env., Nízke Beskydy Mts., 22. V. 2006 , Manko lgt .

Adults (all faunistic records from Slovakia) (CZB, CCB, CKB, NMW, SNM): SLOVAKIA: 1 ♀, 1 ♂: Svetlička stream, Svetlice env., Nízke Beskydy Mts., 49°09'58''N, 22°01'33''E, 300m a.s.l., 18. X. 2003 ; 1 ♂: Laborec river , Mokré lúky pod Č erti ž ným, Č erti ž né env., Nízke Beskydy Mts., 49°20'31''N, 21°50'10''E, 402m a.s.l., 19. X. 2003 ; 12 ♀♀: Svetlička stream, Svetlice env., Nízke Beskydy Mts., 49°09'58''N, 22°01'33''E, 300m a.s.l., 16. VI. 2004 , Za ť ovičová lgt .; 1 ♀: Výrava stream, Svetlice env., Nízke Beskydy Mts., 49°09'35''N, 22°00'54''E, 293m a.s.l., 16. VI. 2004 , Za ť ovičová lgt .; 15 ♀♀: Svetlička stream, Svetlice env., Nízke Beskydy Mts., 49°09'58''N, 22°01'33''E, 300m a.s.l., 22. VII. 2005 , Č iampor & Za ť ovičová lgt .

Distribution and habitat. In general, the distribution of Stenelmis puberula has not been known sufficiently until now. According to the Catalogue of Palaearctic Coleoptera , it is known from Europe ( Armenia, Bosnia Herzegovina, Slovakia, Ukraine, Caucasus) and Asia ( Iran, Israel, Lebanon, Syria, Turkmenistan, Turkey) ( Jäch et al. 2006). In Slovakia, occurrence of the species is restricted exclusively to streams in the northeastern corner of the country, near the Polish and Ukrainian borders ( Fig. 43 ). Orographicaly the studied region falls into the province Východné Karpaty (the Eastern Carpathians), the subprovince Vonkajšie Východné Karpaty (the Outer Eastern Carpathians) and the Nízke Beskydy and Poloniny areas. All streams where S. puberula was found belong to the Laborec river basin ( Kodada et al. 2004).

The steams under consideration are of middle size, approximately 5–10 m wide, with slowly running water and a low slope. They lie at an altitudinal range 300–402 m a.s.l. and have a small catchment area (10– 100 km 2). Their geological bedrock is formed mainly by flysch. The substrate is relatively uniform, consisting of pebbles, cobbles and gravel, partly supplemented by submerged wood and moss. All localities are located close to human settlements and the species is tolerant to their moderately organically polluted water.

S. puberula was found in association with other elmid species: Elmis maugetii Latreille , Esolus parallelepipedus (Müller) , Limnius volckmari (Panzer) ; also, to a lesser extent, Elmis aenea (Müller) , E. obscura (Müller), Esolus angustatus (Müller) , E. pygmaeus (Müller) , Limnius intermedius Fairmaire , L. perrisi (Dufour) , Riolus cupreus (Müller) and R. subviolaceus (Müller) (Za ť ovičová et al. 2004).

Figures

FIGURE 1. Habitus of Stenelmis puberula larva.

FIGURE 43. Distributional records of Stenelmis puberula Reitter from Slovakia.

FIGURES 23–31. Stenelmis puberula larva, 23) protergum, lateral depression with rimmed setiferous pits; 24) protergum, posterior angle; 25) long tergal seta; 26) meso- and metasternum, ventral view; 27) right fore-leg, ventral view; 28) left fore-leg, dorsal view; 29) fore-leg, detail of femur; 30) fore-leg, detail of tibia; 31) fore-leg, detail of tarsungulus.

FIGURES 32–42. Stenelmis puberula larva, 32) right mid-leg, dorsal view; 33) left hind-leg, dorsal view; 34) mid-leg, detail of tibia; 35) hind-leg, detail of femur-tibia articulation; 36) detail of abdominal forked scales; 37) detail of abdominal tergum, lateral view; 38) venter of abdominal segments; 39) abdominal tergites, dorsal view; 40) abdominal segment 9, dorsal view; 41) abdominal segment 9, lateral view; 42) abdominal operculum, hooks and anal gills.

FIGURES 2–11. Stenelmis puberula larva, 2) head, dorsal view; 3) head, dorso-lateral view; 4) head, ventral view; 5) antenna, dorsal view; 6) antenna, detail of pedicel basis; 7) antennal flagellum and sensorium; 8) labrum, dorsal view; 9) labrum, detail of admedian apical tufted scale; 10) labrum, ventral view; 11) same, detail of serrate scales on anterior margin.

FIGURES 12–22. Stenelmis puberula larva, 12) left mandible, ventral view; 13) right mandible, ventral view; 14) left maxilla, ventral view; 15) same, detail of prebasal tufted scales; 16) left maxilla, detail of lateral seta; 17) right maxilla – galea, lacinia, palpus, ventral view; 18) mouth parts, ventral view; 19) labium, ventral view; 20) labial palpus, ventral view; 21) same, detail of apical sensory field; 22) labium, dorsal view.