A New Species of Xenotriphleba Buck (Diptera: Phoridae) from Baltic Amber

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    A New Species of Xenotriphleba Buck (Diptera: Phoridae) fromBaltic AmberAuthor(s): Brian V. BrownSource: Proceedings of the Entomological Society of Washington, 111(1):33-37.2009.Published By: Entomological Society of WashingtonDOI: http://dx.doi.org/10.4289/0013-8797-111.1.33URL: http://www.bioone.org/doi/full/10.4289/0013-8797-111.1.33

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  • A NEW SPECIES OF XENOTRIPHLEBA BUCK (DIPTERA: PHORIDAE)FROM BALTIC AMBER

    BRIAN V. BROWN

    Entomology Section, Natural History Museum of Los Angeles County, 900

    Exposition Boulevard, Los Angeles, CA, 90007, U.S.A. (e-mail: bbrown@nhm.org)

    Abstract.A new fossil species of the enigmatic genus Xenotriphleba Buck, X.antiqua, is defined from a single specimen in Baltic amber. Its differences from andsimilarities with the single extant species, X. dentistylata Buck, are discussed.

    Key Words: Diptera, Phoridae, Xenotriphleba, fossil, amber

    The genus Xenotriphleba Buck is one of

    the most unusual non-metopinine phorids

    that has been described in recent years.

    Because specimens of the sole species, the

    European X. dentistylata Buck, bear a

    suite of characters that make their rela-

    tionship to other phorid genera highly

    problematic, Buck (1997) tried but was

    unable to place them within the systematic

    framework proposed by Brown (1992).

    Specimens of X. dentistylata Buck are

    rarely collected, and their natural history

    is unknown. The type series included

    specimens found in Germany and Swit-

    zerland, and there are additional male

    specimens in the collection of the Natu-

    ral History Museum of Los Angeles

    County (LACM) from Russia (near

    Moscow) and far eastern Russia (see

    also similar records in Michailovskaya

    2004). Records of occurrence in Hungary

    (Papp 2002) and Poland (Durska et al.

    2005) further indicate the widespread

    distribution of this species.

    Because of the systematic questions

    raised by this enigmatic genus, the

    discovery of a fossil specimen is of great

    interest. The new species is defined

    below, with emphasis on differences

    from X. dentistylata.

    SYSTEMATICS

    Xenotriphleba Buck

    Xenotriphleba Buck, 1997: 351. Type

    species: Xenotriphleba dentistylata

    Buck, by original designation.

    Xenotriphleba dentistylata Buck

    Xenotriphleba dentistylata Buck, 1997:

    352.

    Material examined.RUSSIA: Mos-

    cow, Friazevo, 55.75uN, 37.70uE, 1-,25.vii.2000, M. Tretiakov, Malaise trap

    in garden; Primoskiy krai, Gornotayozh-

    noye, 43.66uN, 132.25uE, 1 -, vii.2000,M. Michailovskaya, yellow pan trap

    (both LACM).

    Xenotriphleba antiqua Brown,new species

    (Figs. 15)

    Recognition.This fossil is classified

    in the genus Xenotriphleba based on the

    presence of large tibial setae, one pair of

    reclinate supra-antennal setae, large

    rounded surstyli with thick, peglike setae

    medially, and the lack of wing vein* Accepted by David R. Smith

    PROC. ENTOMOL. SOC. WASH.

    111(1), 2009, pp. 3337

  • Figs. 12. Xenotriphleba antiqua. 1, Head, anterior. 2, Right wing, dorsal.

    34 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON

  • A1+CuA2. It differs from the definitionof X. dentistylata by the much larger

    body size, the presence of wing vein R2+3,

    the presence of a long foretibial seta, and

    other details listed in the description and

    Table 1.

    Description of holotype.Body

    length 3.2 mm (not including termina-

    lia). Frons relatively narrow, approxi-mately 0.34 head width (Fig. 1). Usual

    12 frontal setae (arranged 4-4-4) present,

    plus one pair of reclinate supra-antennal

    setae (Fig. 1). Flagellomere 1 oval,

    slightly pointed, arista dorsal, preapical.

    Palpal setae relatively short. Anepister-

    num bare, without furrows. Scutellum

    with two subequal pairs of setae. Winglength 2.85 mm. Costa 0.56 wing length.

    Vein R2+3 present (Fig. 2). First costal

    sector not measurable, second costal

    sector (insertion of vein R1 to insertion

    of vein R2+3) 1.8 times length of sector 3

    (R2+3 to end of costa). Vein Rs notthickened, with row of about 20 extreme-

    ly short, widely spaced setae extending to

    approximate level of vein R2+3. Vein

    A1+CuA2 (fourth thin vein) not visible(Fig. 3). Foretarsomeres elongate, not

    shortened as in X. dentistylata. Foretibia

    with one long dorsal seta near midlength

    and eight smaller ones more distally(Fig. 3). Midtibia with pair of setae near

    base, one anterior and one posterior, and

    one long anterior seta near apex; apical

    seta clearly longer than width of tibia.

    Hind tibia with two long anterodorsal

    setae, one slightly basal to midlength and

    one near apex (Fig. 3), and one poster-

    odorsal seta near base. All tibiae lackingsetal palisades and ctenidia. Male termi-

    nalia largely obscured (on left side by

    lobelike distortions of the abdominal

    membrane), but small rounded cercus

    and large surstyli visible (Fig. 4), as in X.

    Fig. 3. Xenotriphleba antiqua, habitus, left lateral (blank areas obscured by milky substance in amber).

    VOLUME 111, NUMBER 1 35

  • dentistylata. Medial surface of at least

    left surstylus with peglike setae (Fig. 5,

    only visible from right side by tilting

    specimen).

    Derivation of species name.From

    Latin antiquus for old.

    Holotype.-, Baltic amber, localityunknown, specimen number G 1283,

    University of Gottingen collection, Ger-

    many.

    Systematic affinities.Buck (1997)

    proposed some apomorphic characters

    for genus Xenotriphleba based on male

    and female specimens of X. dentistylata.

    Three of these were given as definite apo-

    morphies of the group: absence of vein

    R2+3, absence of vein A1+CuA2, andstructure of female tergite 6. Based on X.

    antiqua, however, the absence of vein R2+3might have occurred after the origin of the

    genus, in the lineage leading to X. dentis-

    tylata only. Similarly, the lack of a

    dorsobasal foretibial seta in X. dentistylata

    may be the result of a loss of this structure

    after the origin of Xenotriphleba.

    Many of the character states in which

    X. antiqua visibly differs from X. dentis-

    tylata seem to be present in a primitive

    state in X. antiqua (Table 1). One inter-

    esting character in this regard is the

    presence of a nearly complete row of

    setulae along the dorsal surface of vein

    Figs. 45. Xenotriphleba antiqua, male terminalia. 4, Left lateral. 5, Apex, right lateral.

    Table 1. Comparison of character states in specimens of extinct fossil Xenotriphleba antiqua and

    extant X. dentistylata.

    Character State X. antiqua X. dentistylata

    body length large (3.2 mm) small (1.3 mm)

    frontal width narrow (0.34 head width) broad (0.61 head width)

    palpus with short setae with long setae

    anterior scutellar seta subequal to posterior much smaller than posterior

    vein R2+3 present absent

    vein Rs setulose with one basal seta

    vein Rs thin thickened

    foretibia with dorsal seta without setae

    foretarsomeres elongate short

    36 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON

  • Rs. Although this character is useful for

    separating some modern genera (such asAnevrina Lioy and Aenigmatias Meinert),

    it is also unexpectedly present in some

    fossil species of modern genera that lack

    it, such as Hypocera Lioy and Chaeto-

    pleurophora Schmitz (Brown in press).

    Possibly this character was a groundplan

    condition of the common ancestor of

    these groups. Some primitive charactersof X. antiqua, such as the presence of

    vein R2+3 and the setulose Rs, are also

    found in another phorid with separate,

    subequal surstyli, Burmophora Beyer, a

    genus that Brown (1992) proposed re-

    tained the most primitive male surstyli

    known at the time.

    Characters that might be apomorphic inX. antiqua, relative to X. dentistylata, are

    the narrow frons and the short setae of the

    palpus. Without detailed knowledge of the

    outgroup of Xenotriphleba, however, it is

    difficult to know whether these characters

    are truly apomorphic within the genus.

    Unfortunately, the new fossil species

    does not give us any new insights into theclosest relatives of Xenotriphleba. The

    ancestry of phorid genera is a question

    being addressed using molecular data by B.

    Brown and P. Smith (in preparation), after

    preliminary work by Cook et al. (2004).

    ACKNOWLEDGMENTS

    Illustrations were skillfully producedby Brian Koehler. I thank Mike Reich

    for the loan of phorid specimens in

    amber from the collection in Gottingen,Germany, G. Kung for commenting on

    an earlier version of the manuscript, and

    reviews by M. Buck and H. Disney. My

    research on non-metopinine phorids is

    funded by NSF grant DEB 0516420 to B.

    Brown and P. Smith.

    LITERATURE CITED

    Brown, B. V. 1992. Generic revision of Phoridae of

    the Nearctic Region and phylogenetic classifi-

    cation of Phoridae, Sciadoceridae and Irono-

    myiidae (Diptera: Phoridea). Memoirs of the

    Entomological Society of Canada, No. 164,

    144 pp.

    . In press. Novel character states in fossil

    species of modern phorid genera (Diptera:

    Phoridae). Studia Dipterologica.

    Buck, M. 1997. A new genus and species of

    Phoridae (Diptera) from central Europe with

    remarkably primitive male genitalia. Entomo-

    logica Scandinavica 28: 351359.

    Cook, C. E., J. J. Austin, and R. H. L. Disney.

    2004. A mitochondrial 12 s and 16 s rRNA

    phylogeny of critical genera of Phoridae

    (Diptera) and related families of Aschiza.

    Zootaxa 593: 111.

    Durska, E., E. Kaczorowska, and R. H. L. Disney.

    2005. Scuttle flies (Diptera: Phoridae) of saline

    habitats in the Gulf of Gdansk, Poland.

    Entomologica Fennica 16: 159164.

    Michailovskaya, M. B. 2004. Scuttle flies (Dip-

    tera: Phoridae) of the Far East of Russia.

    Russian Academy of Sciences, Far Eastern

    Branch, V. L. Komarovs Mountain-Taiga

    Station. Dalnauka, Vladivostok. 148 pp.

    Papp, L. 2002. New records of Phoridae (Diptera)

    from Hungary. Folia Entomologica Hungarica

    63: 163180.

    VOLUME 111, NUMBER 1 37

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