~ttune ~e roelgique I ~tlUntt Vtlri ~-2lgie Bullo!!in S.R.B.E.IK.B.V.E., 146 (2010): 173-176 Distribution and phenology ~f t;:e Belgian alderflies (Megaloptera) KoenLOCK Merelstraat 27, B-9000 Gent (e-mail : [email protected]) Abstract Three species of alderflies (Megaloptera) are present in Belgium: Sialis fuliginosa Pictet, 1836, Sialis lutaria (Linnaeus, 175 8) and Sialis nigripes Pictet, 1865. The most common species is S. !utaria, which lives in stagnant waters and slow flowing watercourses. S. fuliginosa is less common since it mainly occurs in moderately fast running forest streams. S. nigripes is the rarest species, because it is restricted to large rivers such as the river Meuse, the river Ourthe and the river Ambl<!ve. No additional species are expected in Belgium. Keywords: Belgium; checklist; Sialis. Samenvatting In Belgie komen drie soorten elzenvliegen (Megaloptera) voor: Sialis fuliginosa Pictet, 1836, Sialis lutaria (Linnaeus, 1758) en Sialis nigripes Pictet, 1865. De algemeenste soort is S. lutaria, die voorkomt in stilstaande wateren en traagstromende waterlopen. S. fuliginosa is minder algemeen omdat de soort vooral voorkomt in matig snel stromende bosbeken. S. nigripes is de zeldzaamste soort omdat deze soort enkel voorkomt in grate rivieren zoals de Maas, de Ourthe en de Ambleve. Er warden geen bijkomende soorten verwacht in Belgie. Resume Trois especes de megalopteres (Megaloptera) sont presentes en Belgique: Sialis fuliginosa Pictet, 1836, Sialis lutaria (Linnaeus, 1758) et Sialis nigripes Pictet, 1865. L'espece la plus commune est S. lutaria, elle vit dans les eaux stagnantes et les cours d 'eau lents. S. fuliginosa est mains commune parce que cette espece prefere les ruisselets a eaux courantes dans les forets. S. nigripes est l'espece la plus rare, cette espece etant limitee aux gros cours d 'eau comme la Meuse, l'Ourthe et l' Ambleve. n n'y a pas d'autres especes attendues pour la Belgique. Introduction to collect them with a net in the vegetation near the water. Alderflies are most active on warm, Alderflies or Megaloptera are insects with a sunny days, especially during the morning. complete metamorphosis. Adults are blackish Although adults have biting mouthparts, there brown, about 1.5 cm long and have two pairs of are no definite records indicating that they feed wings that are held like a roof over the abdomen. (ELLIOTT, 2009). The life of the adults is short, The membranous wings have very conspicuous usually one week and rarely longer than two nerves and the numerous costal veinlets give a weeks. The female attracts the much smaller ladder-like effect along the anterior edge of the male by producing a scent and often a female is wing. Adults have a clumsy flight and do not fly surrounded by several males, however, the long distances from the water. It is therefore easy female copulates only once. The eggs are laid in 173 ~------------------------------------------- --------------------------~ clusters of hundreds on plants above or close to Table 1. ·.:hecklist of the Belgian alderflies (Mega­ the water. :.• pter-·). The first larval instars are essentially planktonic, the second instar descends to the n RDF :{ MI~GALOPTERA bottom and burrows in the mud. The larval Far!:ily Sialidae period lasts almost two years and there' are about .' :ialis fuliginosa Pictet 183 6 10 larval instars, the first seven of which occur 5ialis lutaria (Linnaeus 1758) , Sialis nigripes Pictet 1865 before the first hibernation. The shape of the body is elongately fusiform, typically broadest at L__ ----------------------------~ the head and then slowly tapering towards the tip, where the abdomen terminates in a long, were already reported in the nineteenth century: tapering hairy projection. The seven proximal Sialis fuliginosa Pictet, 1836 and Sialis lutaria segments bear laterally long, cylindrical, five­ {Linnaeus, 1758) {MAC LACHLAN, 1881; DE segmented tapering and hairy tracheobranchiae. SEL YS-LONGCHAMPS, 1888). The third species, Larvae have forwardly-projected mouthparts Sialis nigripes Pictet, 1865, was overlooked until with powerful mandibles, which possess two STROOT (1986) discovered this species in the strong teeth on the inner side. The night-active collection of the Royal Belgian Institute for larva are predacious and with their strong Natural Sciences, where 71 specimens were mouthparts they feed on small invertebrates, present that were already captured in the mainly chironomid larvae and oligochaetes. The nineteenth century. larvae leave the water in early spring when ripe for pupation. The larva digs into the soil close to Recorded species the water and pupates there and later in spring, the adults emerge. Sialis fuliginosa Pictet, 1836 In the present study, all available collection This species has been frequently reported in material was studied and the Belgian literature Belgium {MAC LACHLAN, 1881; DE SELYS­ was reviewed. The collected data were used to LONGCHAMPS, 1888; LAMEERE, 1900; NAVAS, study the distribution and phenology of the three 1909; VAN DER WEELE, 1910; NAVAS, 1912; species occurring in Belgium. STROOT, 1986; CORS et al., 2004; DETHIER et al., 2008). It lives in moderately fast streams and Materials and Methods the upper reaches of rivers, especially in small Most of the studied material belongs to the forest streams. Since this type of streams are collections the Royal Belgian Institute for primarily found in the southern part of Belgian, Natural Sciences, the Gembloux Agricultural the species was most frequently found in that University, the University of Liege and the region (Fig. lA). Adults can be found from the University of Mons. In addition, Luc start of May till the start of July (Fig. 2). CREVECOEUR and the Werkgroep Invertebraten Denderstreek (WID) delivered some unidentified Sialis lutaria (Linnaeus 1758) alderflies. Larvae as well as adults of all species Sialis lutaria is the most common alderfly in of Megaloptera occurring in Belgium can be Belgium and it has often been observed in identified with the keys developed by Belgium (DE SEL YS-LONGCHAMPS, 1888; MEINANDER (1996) or ELLIOTT (2009). The LAMEERE, 1900; V AN DER WEELE, 191 0; identification of adults requires study of the NAVAS, 1912, 1922; LESTAGE, 1920; MICHA, genitalia. Specimens are best be conserved in 1970; LITT, 1975, 1990; ROSILLON, 1983; ethanol, since dried specimens are often difficult STROOT, 1986; DOPAGNE & DETHIER, 2000; to identify because of the deformation after ROSE, 2000; DETHIER et al., 2008). The species desiccation. lives in stagnant waters and slow flowing watercourses. .and it has been found all over the Results country (Fig. 1B). Adults were found from Literature overview March till July, however, the main activity period falls in May and June (Fig. 2). Three species of Megaloptera have been observed in Belgium (Table 1). Two species 174 9 rq, Sialis fuliginosa ~ Qr:~ 8 ~~~:tf!~ /' n.. ....... r-,..... 1'-hl "" ~ 7 ~~ i( lB r- ~ 1"- _f) (. ).~ ~o-r-le ....... b j7 l V 1.. ~~~~ •• I Jf*r'"1 ~ •• .I,J ~ • ~ ... ~ t ,~, • ~---~~11""' ·~ ~ ,. J!l \ r ~] ~ 11 _.." • ~ l.-1 'i' ••~ • fl. lJ J ... "",2. 1-P' ~ I• ..... ~-... ...... ~ • (. II Ill IV V VI VII VIII IX X XI XII ........... J lA\. A ~ ~ 140 \~rJJ Sialis lutaria 120 100 80 60 40 20 0 • ••...tll••tr• • ... II Ill IV V VI VII VIII IX X XI XII la hA e ·~ 70~----------------------------~ ................ ~···(ee • Sialis nigripes ...... L. •LA 60 B ~ .. ,. ~b-1..., so 40 rq, ~.:~ 30 /'\, a..~ ...... .... cy .4~~~.!~~ ~ 20 ~ ~,. 1... lD r...... ~ i~ _V 10 ).~ '-I--r-r r-. 1"-- J7 l '/ I \;~~\-"' I• ,.....b. o+-~--..-.,--~L~.-.r-.--.-.-r--r-o.--4 ~ ~= I II Ill IV V VI VII VIII IX X XI XII ,.., ei..,C: ··- '-Ill., /'-I'" ~'"-'IV ~ Figure 2. Phenology of the Belgian Megaloptera. ) lJ"' ;']• ~ \irV"\. )...! {' h-.- •• occurring in large rivers. In Belgium, it has only t.; ./?...·~ l1 I ·o Fl- 1-?' 1 I/ been captured along the river Meuse, the river ................... '- ( J Ourthe and the river Ambleve (Fig. 1C). Adults ........... LA\. c '"'\ ':J can be found the from the start of May till the "\b-11-JJ end of June (Fig. 2). However, the shown phenology is somewhat distorted because most Figure 1. Distribution of the Belgian Megalopt~r~: specimens were captured during a single capture Sialis fuliginosa (A), Sialis lutaria (B) and Sralls at the start of May in Dinant. nigripes (C). Sialis nigripes Pictet 1865 Discussion After STROOT (1986) added this species to the At le.ast six species of Megaloptera are present Belgian fauna based on specimens that were in Eu~ope, all belonging to the genus Sialis already captured in the nineteenth century but {ASPOCK et al., 1980). However, based on their that were not recognised as such. Afterwards, distribution, no additional species are expected in Sialis nigripes has only been reported ?Y Belgium. Since alderflies have not yet been EVRARD & MICHA ( 1995). It is a spectes studied systematically, the three species 175 ----~ occurring in Belgium are undoubtedly more EVR:..RD ~--~. & MICHA J.-C., 1995.- Relation entre la widespread than indicated on the distribution divers!~:! du substrat et la diversite faunistique dans maps (Fig. 1). Although the three species present un hie: belge de la riviere Meuse. Annales de in Belgium prefer different habitats, they can !.imne:ogie, 31:93-103. sometimes be found together. LA:\1EEI~:~ A.. 1900. - Manuel de la faune de 8elg:·:ue. Tome 2. Bruxelles, 858 pp. Acknowledgements LLSTAc:.:: J.A .• 1920.- Le mecanisme de la ponte chez Siat:, /ut aria L. (Megaloptera). Annales de In the first place, I would like to thank the Royal Bioiagie Lacustre, 10 : 221-223. Belgian Institute of Natural Sciences, the Gembloux Lrrr R., 1975. - Observations sur Sialis lutaria L. Agricultural University, the University of Mons and Revue Vervietoise d'Histoire Nature/le, 32: 16-21. the University of Liege for the opportunity to study LIIT R., 1990. -Observations sur l'accouplement de their coiiections. For the help during the study of the Sialis lutaria Linne (Nevroptere/Megaloptere).