The pygmy moths (Nepticulidae) include some of the smallest moths in the world. In some species the winglength measures just over one millimetre (GARCÍA-BARROS et al. 2017). Consistent with theirtiny size, little is known about the biology and distribution of many species, although the larval leafmines of the majorityof species are quite characteristic and more often found thanthe moths. Especiallywhenthe caterpillars do not make such mines, the distribution maps showstill manygaps as few people collect or photograph these tiny insects. Despite of being described over a hundred years ago, and being a relatively large nepticulid species (wingspan 6–7 mm), knowledge about the distribution of thespecies

Bohemannia auriciliella (DE JOANNIS, 1909)

in Europeonly increased in thepast five decades. Including the new records presented here, 28 specimens of this species are now known from throughout Europe.

It all starts in the year 1909 when Nepticula auriciliella was described by J. DE JOANNIS on one female specimen, collected in Vannes byhisbrother L. DE JOANNIS during the 17 preceding years (France, département Morbihan). Thespecies was more or less forgotten for 70 years, and KLIMESCH (1975) contributed to that by synonymizing it with Bohemanniaquadrimaculella (BOHEMAN, 1853).

Around the same time, another specimen was discovered in Kent (Great Britain). The well-known British Microlepidoptera specialist MAITLAND EMMET publishedthe find by E.S. BRADFORD in 1974 as a new species, Ectoedemia bradfordi EMMET, 1974, also based on the advice of JOSEF KLIMESCH, who did not see the resemblance with JOANNIS’ type that he must have seen before. The secondspecimenof “ Ectoedemia bradfordi ” wasfoundamongst unidentified material in the collection of the Zoological Museum Amsterdam, caught already in 1931 in Hatert, near Nijmegen (Netherlands) (VAN NIEUKERKEN 1982).

Eventually, in 1986, the second author discovered the synonymy of the male Ectoedemia bradfordi EMMET, 1974 with the female Nepticula auriciliella DE JOANNIS, 1909 basedon externals, and recombined it with Bohemannia STAINTON, 1859 (VAN NIEUKERKEN 1986a). Soon thereafter he found an additional old specimen in the Copenhagen collection: a female moth from Southampton, accidentally reared in 1937 by W. FASSNIDGE (VAN NIEUKERKEN 1986b). Step by step, more specimens were found. The Netherlands followed withtwomore records fromthe year 1988 (Meijnweg and Mariapeel). In the next decadeactive Britishand Dutchcollectors found more specimens: 1993 (Lover, South Wiltshire), Twello and Wageningen-Hoog (Gelderland 1996), and two moths from Gietelo (Gelderland) at the turn of the millennium. Additional records from Great Britain presumably document the activity of British microlepidopterists: moths were found in 2001 (Berkshire), 2003 (Hampshire), 2010 (Surrey), 2011 (Buckinghamshire), 2014 (Suffolk), 2015 (Southend-on-Sea) andreached the point of culmination in 2017 with three new records (Gloucestershire, Buckinghamshire and Worcestershire).

Nevertheless, after 2000 thespecies also shows up in other European countries. In 2003 it appears in Czechia (LIŠKA et al. 2005), and 2007 in Switzerland (SWISS-LEPTEAM 2010). The first record for Bulgaria is made in 2002 (Burgas; two specimens, leg. JARI JUNNILAINEN), here published for the first time, a second French specimen was collected in the Pyrenees (2010), and two new specimens were recently found in the Netherlands (2015, 2018), here recorded (Table 1, Fig. 5).

Inthelight of thesedata, Germanywould perfectly fit in the distribution. Inthis paper the long awaited record is reported: on the 13th of June 2018 one specimenof Bohemannia auriciliella was collected on a sheet with 160 W mixed light, 2 x 18 W black light, 2x 20 Wsuperactinic light during a public mothing event in the Eilenriede, the city forest of Hannover. There, aroundthe “Waldstation” (which isa place to learn more about the forest‘s ecosystem) the biotope type can be classified as “Bodensaurer Buchenwald” (literally “beech forest on acidic soil”), with a tree ageof 65–130 years. Other treesoccurring there, besides European beech (Fagus sylvatica, Fagaceae), are Scots pine (Pinus sylvestris, Pinaceae), European spruce (Picea abies, Pinaceae), Europeanlarch (Larix decidua, Pinaceae), oaks (Quercus sp. Fagaceae), European black alder (Alnus glutinosa, Betulaceae), Silver birch (Betula pendula, Betulaceae) and Douglas fir (Pseudotsuga menziesii, Pinaceae). Since a few ponds have been laid out in close proximity to the “Waldstation”, the air humidity is relatively high.

Asampleof the Hanoverian specimen was sequenced by the Canadian Centre for DNA Barcoding (Guelph). The result was very surprising, and was confirmed by EvN whom TS sent a photoof themothper email. Three other specimens were barcoded in Leiden according to procedures as described before (DOORENWEERD et al. 2016, VAN NIEUKERKEN et al. 2012). In all now four specimens have been barcoded, and all show almost the same sequence, with Barcode Identification Number BOLD: ACG8823, and a maximal distance of 0.16 %. The records can be seen on the BOLD Website: http://dx.doi.org/10.5883 /BOLD: ACG8823. The Nearest Neighbour interestingly is the unrelated Gonionota amauroptera CLARK, 1971, a Depressariidae from Argentina. Thebarcode distance to other known Bohemannia species is always larger than 15 %.

Bohemanniaauriciliella (Figs 1, 2) is relatively easy to recognise. It is one of the medium large Nepticulidae with a yellow head, wingspan 6–7 mm, collar rather small withlamellar scales (as in Stigmella species) andscape (eyecap) withthe posteriorquarter grey (but thisis notthe case in one female) and a relatively long antenna with 44–53 segments in male, 35– 38 in female. The forewing has a silver fascia beyond the middle, sometimes broken in two spots, and a brassy basal quarter. Bohemannia quadrimaculella (BOHEMAN, 1853) is larger, 7.0– 8.5 mm wingspan, has a uniform scape, antenna white tippedand forewingwithouta brassy base. Only some Stigmella species have a scape withadark edge, males of themuchsmaller S. betulicola (STAINTON, 1856), S. alnetella (STAINTON, 1856) and the male of S. lemniscella (ZELLER, 1839), but that has a black headand black androconialscales onthe hindwing. Seealso VAN NIEUKERKEN & JOHANSSON (1990) and LAŠTŮVKA & LAŠTŮVKA (1997), also for genitalia illustrations. Themalegenitaliaare very characteristic (Fig. 3), thefemale genitalialack the characteristic signa of most related species, theterminal segmentsof theholotype are illustrated in Fig. 4.

Considering the small size of this species and theonlyfewinterested partiesfor very small moths like Nepticulidae, it seemsnot so astonishing that Bohemannia auriciliella was discovered relatively late in Germany. Yet this has more reasons. There remains still someuncertaintyconcerning thehost plant and especiallytheimmature stages. What we know for sure is that adults occurbetweenlate Mayand August, with most records from June and early July. Thehost plant is thought tobe birch, mostly because the collection label of W. FASSNIDGE‘S specimen says it was reared from birch. EMMET (1987) suggested a scenario that FASSNIDGE reared themoth onlyaccidentally from branches collected to get Lampronia fuscatella (TENGSTRÖM, 1848), which lives in twig galls in birch. Unfortunately, there are no further notes by FASSNIDGE to enlighten this case. This was the exclusive record of a larva of B. auriciliella; since then it has not been found again.

If one considers that the main method to find pygmy moths is by searching their mining tracks, it seems clear thatthemine of B. auriciliella can not be easily recognised. So the larva‘s lifestyle is expected to be concealed; it is unlikely to be a leaf miner. Perhaps the larvalives inside abud orapetiole (VAN NIEUKERKENet al. 1986b), as it is known from a related species, Bohemannia quadrimaculella (BOHEMAN, 1853), which most likely inhabits alder buds (EMMET 1984, VAN NIEUKERKEN 1986c).

Further, it may be interesting, that one moth was beaten from birch (VAN NIEUKERKEN et al. 1993), although all other specimens were swept from different bushes orlow vegetation, orcame to light, like the Hanoverian specimen did. At least one prominent silver birch is growing approximately ten metres apart fromthe sheetwhere it was collected. Nearby there are also black alders next to the ponds‘ edges. All Dutch records are also from relatively poorsandy soils with birch commonly present. However, itisdoubtful that birch occurs at the more Mediterranean localities in Bulgaria and the Pyrenees. Theelusive larvallife history is oneexplanation, but still B. auriciliella is muchless frequentlyfound than B. quadrimaculella, so that possiblyalso theadult is moreelusive and more difficult to find.

Although B. auriciliella wasdescribed 111 years ago, its larva and lifecycle are still unknown. Furthermore, it is expected to be less scarce than it seems, as the known distributioncovers alarge part of Europe, and more andmore specimens are found, especially in countries with many active microlepidopterists. What we need, to prove this, isasuitable methodforfinding the larva. By now many Nepticulidae species can be recorded only by the larva ' s host plant and their way of mining. For B. auriciliella this approvedmethod hopefully is possible too – we are lacking only the knowledge to do so. This enigma shouldencourageus to finally disclosethe secret of its hidden biology. The recent finding and photographing of the similarlypoorlyknown larvalfeedingof Etainia species inwinter issomewhatpromising in this respect (SOBCZYK et al. 2018).