This Is a Postrprint of the Paper Published in the Journal Cretaceous Research
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1This is a postrprint of the paper published in the journal Cretaceous research 2https://www.sciencedirect.com/science/article/pii/S019566711730229X and its posted here in 3accordance with the journal’s self-archiving policies 4A new genus of Buchonomyiinae (Diptera, Chironomidae) from Late Cretaceous Burmese 5amber, with the phylogeny of the subfamily revisited. 6Viktor Baranov1,2*, Tomasz Goral3 and Andrew Ross4 7 81Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310,12587, 9Berlin, Germany 102Humboldt University of Berlin, Faculty of Mathematics and Natural Sciences, Geography 11Department, Rudower Chaussee 16, 12489 Berlin, Germany 123Imaging and Analysis Centre, Natural History Museum, London, United Kingdom 134 Department of Natural Sciences, Chambers St., National Museum of Scotland, Edinburgh, 14EH1 1JF, UK 15*present address: Senckenberg Research Institute and Natural History Museum Frankfurt, 16Department of River Ecology and Conservation, Clamecystrasse 12, 63571 Gelnhausen, 17Germany. 18Viktor Baranov is corresponding author. 19Highlights 20 Here we are presenting the oldest record of the Chironomidae subfamily 21 Buchonomyiinae 22 This subfamily is a sister group to the rest of the family 23 This discovery is representing a second genus in the previously monotypic group 24 New genus is shading a light on the evolution of the subfamily 25Abstract 26Among the eleven modern subfamilies of non-biting midges (Diptera: Chironomidae), 27Buchonomyiinae are the most primitive and considered to be the sister group to the rest of the 28chironomids. The subfamily is monotypic with a single genus Buchonomyia, including three 29Recent species from Europe, South-East Asia and Central America, and a single fossil 30species, B. succinea Seredszus and Wichard, 2002, from Baltic amber. The elusive nature of 31the larvae and pupae, who develop as parasites or are commensal of caddisfly larvae, means 32that records of recent Buchonomyiinae extremely rare. From the latest dated phylogeny of the 33Chironomidae, the Buchonomyiinae branched from the rest of the Chironomidae in the Early 34to Middle Jurassic. Here we present the oldest record of the subfamily Buchonomyiinae, from 35Late Cretaceous Burmese amber. The record is represented by a new genus 36Furcobuchonomyia, with a single species F. saetheri sp. nov. Bayesian analysis firmly places 37the new genus as the sister group to the rest of the Buchonomyiinae. Thus the discovery of 38this genus is sheding new light on the origin of the most basal group of the Chironomidae. A 39species level key to the subfamily is included. 40Introduction 41With almost 6000 described species, non-biting midges (Diptera: Chironomidae) are among 42the most diverse and abundant aquatic insects in the world (Ferrington, 2008). Non-biting 43midges are widely used as indicators of ecological status in freshwaters, due to the close and 44specific association of the preimaginal stages with their habitat (Armitage, Cranston, & 45Pinder, 1995; Walker, 2001). The family has also left a rich fossil record dating back to the 46Triassic, with numerous extant genera known from the Paleogene (Ansorge, 1999; Kalugina, 471980; Krzemiński & Jarzembowski, 1999; Seredszus & Wichard, 2007; Zakrzewska, 48Krzeminski, & Gilka, 2016, Doitteau & Nel, 2007). Chironomids are one of the most 49common taxa in amber, sometimes comprising up to 70% of all animal inclusions (Doitteau 50& Nel, 2007; Wichard, Gröhn, & Seredszus, 2009). Their abundance in amber, together with 51knowledge about the ecological requirements of modern representatives, allows conclusions 52on palaeoenviromental conditions to be made (Grund, 2005; Seredszus & Wichard, 2007). 54Among the 11 extant subfamilies of chironomids, Buchonomyiinae has a controversial 55taxonomic history (Murray & Ashe, 1985). The first known species of the subfamily – 56Buchonomyia thienemanni Fittkau, 1955 was described by E.J. Fittkau based on a single male 57from Hesse, Germany in 1955. It was classified as a strange representative of subfamily 58Podonominae (Fittkau, 1955). Later, Fittkau suggested placement of the genus into the 59subfamily Orthocladiinae, as a highly plesiomorphic representative (Brundin & Sæther, 1978; 60B. D. A. Murray & Ashe, 1985). It was not until 1978, when both an adult male and a female 61of the second species – B. burmanica were described by Brundin & Sæther (1978), that the 62subfamily Buchonomyiinae was established, mostly based on female characters (Brundin & 63Sæther, 1978). Since the erection of the subfamily, it’s position in the family tree of the 64Chironomidae was disputed, Brundin and Sæther (1978) and Sæther (1979, 2000) argued that 65Buchonomyiinae should be placed within the clade 66Chironominae+Orthocladiinae+Diamesinae+Prodiamesinae. Later, after the description of 67the 1st instar larvae, 4th instar larvae and pupa, the position of the subfamily within a more 68basal clade including Tanypodinae+Podonomiinae+Aphroteninae was decided (Murray & 69Ashe, 1985). The dated molecular phylogeny of the family (Cranston et al., 2012) 70unexpectedly and robustly placed the subfamily as the sister group to the rest of the 71Chironomidae, suggesting an Late Triassic/Early Jurassic origin of the subfamily, though still 72being closer to clade Tanypodinae+Podonomiinae+Aphroteninae. The controversial position 73of the subfamily is partially due to its rarity, as only a handful of specimens of each species 74have ever been caught (Ashe, O’Connor & Murray, 2015), due to the elusive nature of larvae 75and adults. Rarity seems to be a result of it’s specialised larval biology, involving parasitism 76of caddisfly larvae belonging to the family Psychomyiidae (Ashe et al., 2015). It is assumed 77that Buchonomyiinae larvae live as parasites of the Psychomyiidae, pupating within the 78caddisfly larval case. In Ireland the distribution of B. thienemanni seems to closely follow 79that of Psychomyia pusilla (Fabricius, 1781) (Ashe et al., 2015). It is difficult however to 80associate Buchonomyia larvae exclusively with Psychomyiidae, as while modern species of 81Buchonomyia co-exist with numerous Psychomiidae species in Europe and Burma (Wichard, 82Ross, & Ross, 2011), and B. succinea was co-inhabiting the Baltic amber forest with at least 835 species of Psychomyiidae (Wichard, Gröhn, & Seredszus, 2009), there are no records of 84this family from Costa Rica, thus B. brundini probably has a different host or a different 85lifestyle (Holzenthal & Calor, 2017) 86Such unusual biology of the larvae makes records of Buchonomyiinae extremely rare, with 87only B. thienemanni known from more than the single (type) locality (Andersen & Sæther, 881995; Ashe et al., 2015; Brundin & Sæther, 1978; Fittkau, 1955). Also the abundance of 89plesiomorphic characters in the genus Buchonomyia has made placement based on the 90morphology alone extremely difficult. 91The subfamily was monotypic with a single genus Buchonomyia, including three Recent 92species from Europe, South-East Asia and Central America, and a single fossil species B. 93succinea Seredszus & Wichard, 2002, from Baltic amber. Currently Buchonomyiinae are 94known from Western and Central Europe, Northern Africa (B. thienemanni), Northern 95Myanmar (B. burmanica), Costa-Rican mountains (B. brundini), Baltic Amber (B. succinea) 96(Murray, Langton, O’Connor & Ashe, 2013) and now from Burmese amber. 97Due to the extreme rarity of the subfamily Buchonomyiinae in the fossil record and its basal 98position in the Chironomidae evolutionary tree, any new fossil of the Buchonomyiinae is of 99utmost interest. Here we describe a new genus and species of the subfamily Buchonomyiinae 100from Late Cretaceous Burmese amber. This new genus bears a close resemblance to 101Buchonomyia, while possessing a number of specialized traits in the structure of the 102hypopygium and legs. This new record is the oldest known for the subfamily. 103 104Geological context 105Burmese amber, from Myanmar, is proving to be the most interesting of all the Cretaceous 106ambers. Until relatively recently it was regarded as rare and difficult to get hold of but over 107the past few years new mines have opened up and it is now freely available. As a result there 108has been a proliferation of papers describing new species, demonstrating the high diversity 109that has been preserved in this amber. By the end of April 2017 481 species of insects had 110been named (Ross, 2017). Although 141 specimens of Chironomidae were listed by Grimaldi 111et al. (2002), demonstrating they are relatively common in Burmese amber, no species have 112been named until now. 113The specimen studied here was purchased by National Museums Scotland from Scott 114Anderson in 2010. It came from the Noije Bum Amber Mine, Kachin State, Myanmar, 115described by Cruickshank & Ko (2003). The age of Burmese amber has been controversial. 116Originally considered to be Miocene, it is now accepted as Cretaceous (see Ross et al., 2010), 117however the exact age has been under dispute. Palynomorph dating suggested an Albian\ 118Cenomanian age, and a Mortoniceras ammonite suggested it was late Albian (Cruickshank & 119Ko, 2003). However radioactive zircons provided an age of 98.79 +/- 0.62 Ma, thus early 120Cenomanian (Shi et al., 2012). This provided a minimum age for the bed and not the amber 121as it could have taken time for the amber to be deposited, particularly as many of the pieces 122had been bored by pholadid bivalves. It has recently been established