PROC. ENTOMOL. soc. WASH. 111(1),2009, pp. 33-37
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:
[email protected])
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 * Accepted by David R. Smith
below, with emphasis on differences from X. dentistylata. SVSTEMATICS
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, 55.75°N, 37.70 o E, 16, 25.vii.2000, M. Tretiakov, Malaise trap in garden; Primoskiy krai, Gornotayozh noye, 43.66°N, 132.25°E, 1 6, vii.2000, M. Michailovskaya, yellow pan trap (both LACM). Xenotriphleha 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
•
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1
R2+3
2 Figs. 1-2.
Xeno/riphleba antiqua. 1, Head, anterior. 2, Right wing, dorsal.
VOLUME Ill, NUMBER I
Fig. 3.
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Xenotriphleba antiqua, habitus, left lateral (blank areas obscured by milky substance in amber).
A 1+CuA 2 • It differs from the definition of X dentistylata by the much larger body size, the presence of wing vein R 2 + 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. Wing length 2.85 mm. Costa 0.56 wing length. Vein R 2+ 3 present (Fig. 2). First costal sector not measurable, second costal sector (insertion of vein R I to insertion of vein R 2+ 3 ) 1.8 times length of sector 3
(R 2 + 3 to end of costa). Vein Rs not thickened, with row of about 20 extreme ly short, widely spaced setae extending to approximate level of vein R 2 + 3 . Vein A 1+CuA 2 (fourth thin vein) not visible (Fig. 3). Foretarsomeres elongate, not shortened as in X dentistylata. Foretibia with one long dorsal seta near mid length 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 lacking setal 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
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peglike ~~::",;",n~· seta
5 Figs. 4-5.
Xenotriphleba antiqua, male terminalia. 4, Left lateral. 5, Apex, right lateral.
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.-J, Baltic amber, locality unknown, specimen number G 1283, University of G6ttingen 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
R 2+ 3 , absence of vein A]+CuA2 , and structure of female tergite 6. Based on X antiqua, however, the absence of vein R 2 + 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 I). One inter esting character in this regard is the presence of a· nearly complete row of setulae along the dorsal surface of vein
Table I. Comparison of character states in specimens of extinct fossil Xenotriphleba antiqua and extant X. dentistylata. Character State
body length frontal width palpus anterior scutellar seta vein R 2+ 3 vein Rs vein Rs foretibia foretarsomeres
'",
X. antiqua
large (3.2 mm) narrow (0.34 head width) with short setae subequal to posterior present setulose thin with dorsal seta elongate
X. denlisry/ala
small (1.3 mm) broad (0.61 head width) with long setae much smaller than posterior absent with one basal seta thickened without setae short
t
VOLUME III, NUMBER I
Rs. Although this character is useful for separating some modern genera (such as Anevrina 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 characters of X antiqua, such as the presence of vein R 2 + 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 in X antiqua, relative to Xdentistylata, 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 the closest 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 produced by Brian Koehler. I thank Mike Reich
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for the loan of phorid specimens in amber from the collection in G6ttingen, 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 CfTED
Brown, B. V. 1992. Generic revision ofPhoridae 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 sand 16 s rRNA phylogeny of critical genera of Phoridae (Diptera) and related families of Aschiza. Zootaxa 593: I-II. 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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