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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 and

similarities 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. 1–5)

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. 33–37

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

34 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON

A1+CuA2. It differs from the definition

of 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, locality

unknown, 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, and

structure of female tergite 6. Based on X.

antiqua, however, the absence of vein R2+3

might 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. 4–5. 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: 351–359.

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: 1–11.

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: 159–164.

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

tera: Phoridae) of the Far East of Russia.

Russian Academy of Sciences, Far Eastern

Branch, V. L. Komarov’s Mountain-Taiga

Station. Dalnauka, Vladivostok. 148 pp.

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

from Hungary. Folia Entomologica Hungarica

63: 163–180.

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