New spider flies from the Neotropical Region (Diptera, Acroceridae) with a key to New World genera

Abstract Two new genera and five new species of spider flies (Diptera: Acroceridae) are described from the Neotropical Region. A new genus of Philopotinae (Neophilopota brevirostris Schlinger gen. et sp. n.) is described from Mexico, while an unusual new species of Sphaerops Philippi, 1865 (Acrocerinae: Sphaerops micella Schlinger sp. n.) is described from Chile. A new Panopinae genus near Lasia Wiedemann, 1824 (Coquena stangei Schlinger gen. et sp. n.), is described from Argentina and two new species of Pialea Erichson, 1840 (Pialea brunea Schlinger sp. n. and Pialea corbiculata Schlinger sp. n.)are described from Venezuela. Each genus is diagnosed and figured, and a key to species provided. The Neotropical fauna presently includes 19 genera, containing approximately 100 species. A key to New World genera is also included.

appendiculata Philippi, is remarkable in its biology. While most acrocerid larvae are internal parasitoids of spiders, larvae of S. appendiculata are suggested to be external parasitoids (Schlinger 1987). Winterton et al. (2007) placed Sphaerops with Acrocera in a clade that is sister to the rest of Acroceridae, while the remaining acrocerine genera sampled were recovered in a second polyphyletic 'acrocerine' clade sister to Panopinae.
In this manuscript we describe two new acrocerid genera (a philopotine and a panopine) and five new species. A complete key to all 21 genera occurring in the New World is provided.

Material and Methods
Terminology follows Schlinger (1981) as modified by Cumming and Wood (2009), Gillung and Winterton (2011) and Winterton (2012). Type specimens are deposited in the California Academy of Sciences, San Francisco, CA, USA (CAS), and the National Museum of Natural History, Washington DC, USA (USNM). Specimen images were taken at different focal points using a digital camera and subsequently combined into a serial montage image using Helicon Focus software. All new nomenclatural acts and literature are registered in Zoobank (Pyle and Michel 2008).
Forty-three specimens were examined from the two collections listed above. The specimens were compared to previously published descriptions and figures and did not agree with any described species in the case of Sphaerops and Pialea, or described genera in the case of the two new genera. The exact label information for primary types is provided, with line breaks indicated with '/' and handwriting in italics. Any inferred label information is in square brackets. Wing measurements were taken as the length from the base of the distal median plate to the wing tip. Body length was recorded as the distance from the anterior margin of the scutum to the posterior margin of abdominal segment VI when viewed dorsally. The holotype was always included in the series of measured specimens. Distribution maps were made using Simplemappr (Shorthouse 2010).
taxonomy Key to New World genera of Acroceridae 1 Postpronotal lobes greatly enlarged, meeting or nearly meeting along midline to form collar for head; body shape strongly arched (Figs 6, 7) ... Philopotinae: 3 -Postpronotal lobes not greatly enlarged, separate along midline; body not strongly arched (Figs 3, 13 Pairs of tubercles present on tergites II-IV of abdomen; occiput extended posteriorly to form an acute ridge (South America) (Fig. 25)  Diagnosis. Body shape not arched; coloration non-metallic. Head width slightly less than thorax width; nearly spherical in shape; ocellar tubercle raised and rounded with three ocelli; postocular ridge and occiput rounded; posterior margin of eye rounded; eye sparsely pilose with minute setae (not more than 4× length of single ommatidium); eyes either contiguous above antennal base or with antennal base adjacent to dorsal eye margin, contiguous below antennal base; palpus absent; proboscis length greatly reduced with sparse pile; antennae located near or adjacent to ocellar tubercle; flagellum stylate, apex with terminal seta(e); scapes not fused together; postpronotal lobes not enlarged or contiguous medially; antepronotum narrow; subscutellum enlarged; legs not elongated; tibial spines absent; pulvilli present; wing markings and microtrichia absent. Costal vein ending near wing apex; costal margin straight; humeral crossvein absent; R 1 inflated at pterostigma; radial veins straight, veins R 4 and R 5 present as single fused vein; crossvein 2r-m present between M 1 and R 4+5 , bisecting cell r 4+5 , basal portion of cell narrow elongate; two M veins present, not reaching wing margin; discal cell closed; cell m 3 absent; CuA 1 joining M 3 ; anal lobe well developed; alula well developed. Abdomen greatly rounded, inflated, tergites smooth. Comments. Sphaerops is an endemic Chilean genus than can be readily differentiated from all other acrocerine genera based on the sparsely pilose eyes, wing vein A 1 fused to CuA 2 and the bulbous genitalia. Sphaerops is also unique in exhibiting the widest range in size variation within acrocerids. The genus shows remarkable similarity to the Chilean endemic genus Villalus, sharing numerous characteristics such as having the antennae placed away from the ocellar tubercle (except in S. micella) and vein R 4+5 present as a single, unforked, vein. Evert I. Schlinger has reared numerous Sphaerops individuals and reported that the mature larvae fed externally on spiders for up to three weeks. This type of development is unique as all other acrocerids with known larval habits are endoparasitoids until emerging to pupate (Schlinger 1987). Diagnosis. This species is much smaller than S. appendiculata (1.9 mm versus 6.3 mm) and has shorter pile on the thorax and abdomen. It is also unique in having the antennae placed immediately adjacent to the ocellar tubercle, the wing veins pale yellow, and wing veins CuA 2 and A 1 remaining separate.

Key to species of Sphaerops
Description. Male with small body length: 1.9 ± 0.6 mm (1.4-2.4 mm, n = 10) and wing just longer than body: 2.2 ± 0.5 mm (1.7 -2.5 mm, n = 10) setae covering body and legs is fine and short (Fig. 1). Female unknown. Head. Eye dark brown, occiput black, covered with pale yellow pile; ocellar tubercle black; ocelli white, frons dark brown, antennae light brown and placed on mediodorsal eye margin, face dark brown with pale yellow pile, clypeus light brown, bare and shorter than the antennae, mouthparts yellow and strongly reduced. Thorax. Uniformly dark brown with covering pale yellow setae; coxae light brown, femora light brown with apex yellow, tibia light brown with basal third yellow , tarsi light brown, basal and apical tarsomeres longer than middle tarsomeres, lower calypter translucent white and covered with pale yellow setae, halter pale yellow. Wing. (Fig. 2) All wing veins pale yellow except costa, subcosta and R 1 pale brown; pterostigma darker. Abdomen. Background color brown tergites I-II entirely brown, tergite III with posteriomedial portion yellow, tergites IV-VI medially yellow, sternites brown.
Comments. Based on an examination of the voucher specimens of Sphaerops sequenced by Winterton et al. (2007) these were representatives of S. micella sp. n. not S. appendiculata as reported. Therefore the taxon associated with Genbank accession numbers AY140877, AF539875, AY144436, and AY144403 will be changed to S. micella sp. n.  Etymology. The species epithet is derived from the Latin: micella (diminutive feminine) meaning; little, crumb, or small, in reference to the minute size of this species relative to S. appendiculata. Diagnosis. Pile covering body and legs is much longer and denser than in S. micella sp. n. (Fig. 3). Antennae are inserted on the head near but not immediately adjacent to the ocellar tubercle. This species is also much larger (6.3 vs 1.9 mm), has brown rather than yellow wing veins, and the wing veins CuA 2 and A 1 join near the wing margin.

Sphaerops appendiculata
Description. Male with medium body size: (Fig. 3) 6.3 ± 1.2 mm (5.8 -7.0 mm, n = 3) and wing shorter than the body: 5.9 ± 1.4 mm (5.1 -6.4 mm, n = 3). Head. (Fig.  4) Eye dark brown, occiput and ocellar tubercle dark brown, covered with pale yellow pile; ocelli light brown, frons dark brown and strongly reduced, antennae light brown, face dark brown with pale yellow pile, clypeus dark brown, bare and as long as scape and pedicel combined, mouthparts yellow and strongly reduced. Thorax. Uniformly dark brown with dense covering pale yellow pile; coxae dark brown, femora, tibia and tarsi light brown, basal tarsomere longer than remaining tarsomeres, lower calypter pale yellow with light brown margin and covered with dense pale yellow pile, halter yellow. Wing. (Fig. 5) All wing veins brown. Abdomen. Tergites dark brown, sternites dark brown with posterior margin yellow.
Diagnosis. Neophilopota gen. n. is an endemic Mexican genus similar to Quasi, Oligoneura and Philopota. It can be easily distinguished from the Central American genus Quasi as Neophilopota has pilose eyes and well developed mouthparts (forming an elongate proboscis). It shows greater similarity to both the Palearctic Oligoneura and the Neotropical Philopota in having elongate mouthparts and the ocellar tubercle poorly developed. It is easily distinguished from Philopota by having the frons as long as wide (though shorter than the antennae), the insertion of the antennae on the lower part of the frons, the lower facial margin wider in the upper portion than in lateral portions, and the clypeus shorter than the antennae. It can be readily differentiated from Oligoneura by the absence of the palpi, the presence of pile on the frons, the insertion of antennae on the lower portion of the head, the clypeus being shorter than the antennae and the legs greatly elongated. Neophilopota was referred to as 'New Genus A' in the Manual of Central American Diptera (Schlinger 2009).
Comments. The proboscis in the holotype is broken (Fig. 6), but in the paratype it is longer than the head height and shorter than the body length.
Etymology. The species epithet is derived from the Latin: brevis (short) and rostris (beak), in reference to the short length of proboscis in comparison to species of Philopota.   Diagnosis. Coquena is a South American genus readily distinguished from other panopine genera by the minute mouthparts, the ocellar tubercle extremely raised and the iridescent body color. It is closely related to the Neotropical genera Lasioides and Pteropexus, the Nearctic genus Eulonchus, and the New World genus Lasia, as it shares the same wing venation. However it does not have the elongate proboscis present in these genera. Coquena and Lasioides are closely related, monotypic, genera. The mouthparts in Coquena stangei are strongly reduced, whereas they are elongate in Lasioides peruanus Gil Collado, 1928. Coquena shares some attributes with Lasia such as the presence of an alula and having the eyes separate below the antennae. It also shares several characteristics with Eulonchus, principally the extremely raised ocellar tubercle and presence of maxillary palpi.
Etymology. The genus epithet is derived from the Coquena legend of north-western Argentina. Coquena was the son of Mother Earth and was portrayed as a short man dressed in a hat and bright colored poncho. The iridescent coloration, hat-like ocellar tubercle and type locality in northwest Argentina of the type species led to the choice of this name for the genus. Paratypes. Four females, same data as holotype except: genitalia not dissected; EIS specimen numbers are: 013436, 013437, 013438, 013441; and with yellow paratype labels.
Description. Male holotype with medium body size (Fig. 11): 7.80 mm and wing shorter than body: 7.0 mm. Female with medium body size (Fig. 13): 6.7 ± 1.21 mm (6.0 -7.5 mm, n= 4) and wing longer than the body: 7.8 ± 1.2 mm (7.0 -8.5 mm, n= 4). Head. Eyes dark brown and densely covered with pale yellow pile (Figs 12,  14), occiput and ocellar tubercle dark brown and covered with yellow pile, ocelli light brown, frons dark brown with region adjacent to antennae yellow, scape and pedicel light brown with apex yellow, pedicel with light brown pile, flagellum light brown, male flagellum length ~2× height of the eye and petal-shaped, female flagellum length ½ the height of the eye and tapering to apex. Face dark brown with yellow pile, clypeus brown, bare and slightly longer than scape and pedicel combined, mouthparts pale yellow and strongly reduced. Thorax. Iridescent green and densely covered with long yellow pile. Coxae light brown, femora light brown with apical third yellow, tibia and tarsi light brown. Lower calypter transparent covered with dense yellow pile, halter yellow. Wing. Transparent (clear or pale brown), veins brown (Fig. 13). Abdo- men. Tergites iridescent brown densely covered with yellow pile; sternites brown and densely covered with yellow pile.
Etymology. This species is named in honor of Dr. Lionel A. Stange, Florida State Collection of Arthropods, who collected the type series.
Pialea Erichson, 1840 http://species-id.net/wiki/Pialea Diagnosis. Body shape not arched; coloration non-metallic. Head width much narrower than thorax width; hemispherical; ocellar tubercle shape raised, rounded, two ocelli present, anterior ocellus absent; postocular ridge and occiput rounded; posterior margin of   eye rounded; eyes densely pilose; not contiguous above antennal base, rarely contiguous below; palpus absent; proboscis length greatly reduced, with sparse pile; antennae located on middle of frons, either nearer to ocellar tubercle or to mouthparts; flagellum elongate, slightly tapered or paddle-shaped; apex with terminal setae present or absent; scapes fused; postpronotal lobes not enlarged or contiguous medially; antepronotum narrow; subscutellum barely visible beneath scutellum; legs not elongated; tibial spines present apically; pulvilli present; wing markings and microtrichia absent; costal vein ending near wing apex; costal margin straight; humeral crossvein absent; radial veins straight; R 1 not inflated distally; R 4+5 originating at apex of basal cell r 4+5 and then forking into veins R 4 and R 5 (Fig.  36); crossvein 2r-m present between M 1 and R 4+5 , bisecting cell r 4+5 ; cell formed by 2r-m narrow, elongate; R 4 without spur vein; M 1 , M 2 and M 3 present (M 3 fused with CuA 1 ), rarely one M vein or two M veins present, all typically reaching wing margin; discal cell closed; cell m 3 present, CuA 1 joining M 3 and running towards margin; CuA 2 fused to A 1 before wing margin and running towards margin; anal lobe well developed; alula weakly developed; abdomen greatly rounded, inflated; tergites smooth, rounded.
Comments. Pialea is a relatively rare South American genus that comprises four species described from Brazil and another one described from Ecuador. The genus was described by Erichson (1840) for his new species P. lomata from Brazil. Later, Westwood (1876) named a second species, P. lutescens, also from Brazil. Two more species from the Oriental Region were later described in this genus, P. jardinei and P. auripila (Brunetti 1912), but they were subsequently transferred to Astomella Latreille, 1809 and Astomelloides Schlinger, 1959, respectively (Schlinger 1956, 1959. Schlinger (1956) revised the genus and described three more species, P. antiqua, P. capitella and P. ecuadoriensis. Pialea is presumably closely related to Stenopialea Speiser, 1920 (a South African endemic genus) and Archipialea Schlinger, 1973 (Chile) based on antennal and wing characters (Schlinger 1973;Barraclough 1985). Pialea are characterized by the fusion of the scapes and the dichoptic eyes (except in P. capitella). Species in this genus also show strong sexual dimorphism in the length, insertion and shape of the antennae, the length of the abdomen and the color and maculation of the body.  (Fig. 19); antennae inserted in the middle of the head (only known from female) (Fig. 18) . 17); post pedicel longer than head height (Fig. 18); body entirely brown, without yellow markings; R 2+3 not reaching wing margin (Fig. 19); M 2 present; first tarsomere of hind leg much longer than the remaining tarsomeres combined. Description. Female holotype with medium body size (Fig. 16, female body: 9.2 mm) and wing shorter than body (female wing: 8.2 mm). Head. Eyes black and densely covered with long (equal to length of scape) brown pile (Fig. 17), occiput and ocellar tubercle dark brown and covered with brown pile, ocelli brown, frons brown, scape and pedicel brown, pedicel with several long setae, flagellum brown and tapering to apex which bears setae (Fig. 18). Face dark brown with brown pile; clypeus dark brown, half the length of the scape and covered with fine setae; mouthparts light brown and strongly reduced. Thorax. Uniformly light brown and densely covered with long brown pile. Legs brown and densely covered with long brown pile. Lower calypter brown and densely covered with yellow pile; halter light brown. Wing. Transparent with light brown wing veins (Fig. 19). R 2+3 incomplete, not reaching wing margin, M 1 absent, M 2 present. Abdomen. Both tergites and sternites uniformly dark brown.

Key to species of Pialea
Comments. Pialea brunea is closely related to P. capitella Schlinger, 1956 andP. ecuadorensis Schlinger, 1956, sharing with these species the absence of wing vein M 1 . It differs from P. capitella in the eyes being separate below the antennae, and from P. ecuadorensis in the overall brown coloration and presence of M 2 .
Etymology. The specific epithet is derived from the Latin, bruneus -brown; referring to the distinctive entirely brown coloration of the body, which lacks yellow markings.  Diagnosis. Antennae inserted in the middle of the head (male); post pedicel as long as the head height; head, thorax and scutellum black; legs and abdomen black with yellow markings; hind leg with tibia and first tarsomere swollen (Figs 20, 22), twice as wide as the second tarsomere; additional r-m crossvein (2r-m) present.
Description. Male holotype with medium body size (Fig. 20, male body length: 7.3 mm) and wing longer than body (male wing: 8.6 mm). Head. Eyes black and densely covered with dark brown, long (equal to scape length) pile (Fig.  21), occiput and ocellar tubercle dark brown and densely covered with long dark Figure 20. Pialea corbiculata Schlinger sp. n., male holotype, lateral view. Scale bar = 1.0 mm. brown pile, ocelli light brown, frons dark brown, scape and pedicel dark brown, pedicel with yellow setae, flagellum light brown, lacking apical setae. Male flagellum petal like, length ~2× length of scape and pedicel combined. Face dark brown with brown pile, clypeus dark brown, with light brown pile and shorter than scape, mouthparts dark brown and strongly reduced. Thorax. Dark brown and densely covered with long brown pile (Fig. 22). Coxae dark brown, femora yellow with apex of ventral surface brown, tibia yellow with apex brown, tarsi brown, hind leg longer than fore-and mid-leg and with tibia and first tarsomere swollen (twice as wide as mid-leg). Lower calypter brown and densely covered long brown pile, halter brown. Wing. Transparent light brown with brown wing veins; M 1 and M 2 present. Abdomen. Densely covered with light brown pile (Fig. 22). Tergite I and VI brown, tergites II-V yellow with anterior margin and medial line brown; sternites I and VI brown sternite II-V yellow.
Comments. Pialea corbiculata sp. n. is closely related to P. lutescens Westwood, 1876 and P. antiqua Schlinger, 1956, based on the presence of wing vein M 1 . It dif-                fers from those two species by the swollen tibia and first tarsomere of the hind leg and the presence of an additional r-m crossvein (2r-m), which are unique features within Pialea.
Etymology. The species epithet, corbiculata, is in reference to the swollen hind tibia and tarsi which resemble the pollen collecting corbicula of many bees. specimens. Dr. F. Christian Thompson provided assistance with nomenclatural accounts and bibliographic records. This research was supported by the National Science Foundation (DEB award number 0614213) and the Australian Biological Resource Study . Statements and viewpoints expressed herein do not necessarily reflect the opinion of NSF or ABRS. Disclosure: this paper was compiled from notes and specimen determination labels authored by Evert I. Schlinger with the final manuscript prepared by Jessica P. Gillung and Christopher J. Borkent.