Pieza ostenta (Melander) Melander, 2002

Evenhuis, Neal L., 2002, Pieza, a new genus of microbombyliids from the New World (Diptera: Mythicomyiidae), Zootaxa 36, pp. 1-28 : 17-19

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https://doi.org/ 10.5281/zenodo.156131

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scientific name

Pieza ostenta (Melander)

comb. nov.

Pieza ostenta (Melander) , comb. nov.

Mythicomyia ostenta Melander, 1961: 236 . Painter & Painter, 1965: 417. Hull, 1973: 269. Evenhuis, 1983: 483.

Mythicomyia (Mythenteles) ostenta Melander. Hall & Evenhuis, 1986: 339 .

Male. Length: 1.05­1.36 mm. Head. Eyes dichoptic; ocelli nearly in a straight line; lateral ocellus 1.5 its diameter from inner eye margin; frons slightly longer than wide, depressed medially, yellow from level of median ocellus to antennae, with medial black spot; upper 1 / 2 of front with dark hair; antenna black, scape minute; pedicel slightly wider than long; first flagellomere short, ovoid, broadest at or slightly beyond middle, slightly longer than wide; length of second flagellomere equal to width of first flagellomere; face black, narrowly yellow beneath antennae; proboscis black, projecting beyond oral margin for distance much greater than head height; occiput black above with yellow triangular spot medially behind ocellar tubercle, yellow laterally at posterior eye margin, noticeably swollen, with sparse black hairs.

Thorax. Mesonotum dull black with yellow vittae; humeral callus, interhumeral triangular mark, lateral margin (broad and deeply incised behind prealar suture), postalar callus, narrow admedian vitta, and prescutellar area yellow; black color of mesonotum reaching base of scutellum laterally; dorsum of mesonotum with scattered black hairs; scutellum yellow with scattered dark hairs; pleura black, anepisternum with upper portion yellow; medial longitudinal yellow stripe present; coxae and legs yellow, femora dark brown to black on basal two­thirds; apical tarsal segments black; halter with stem and knob yellow to whitish.

Wing. Hyaline; veins brown; costa ending at midpoint between end of veins R 4 + 5 and M 1; vein R 2 + 3 arising at nearly 90 °; cell dm narrowed apically; vein at base of cell m 1 shorter than r­m crossvein.

Abdomen. Dorsum brownish yellow; tergites III­VI with narrow yellow to yellowish white fasciae on posterior margin of each segment; tergites I and II darker brown than succeeding tergites; dorsum with scattered yellowish hairs; venter yellow.

Genitalia ( Fig. 13 View FIGURES 12 ­ 13 ). In lateral view with gonocoxite subquadrate­subtriangular; gonostyli not evident, with paired anteroventral curved structures; gonocoxal apodemes narrow caudally, flaring dramatically to broad, rounded triangular apex; aedeagus with broad, onion­shaped bulb basally, leading to long, thin aedeagal tip; aedeagal apodeme large, axeshaped, with small, thin lateral vanes; lateral rami corsair wing­shaped, slightly broadened distally in ventral view; epandrium elongate triangular, pseudo­surstylus incurved, not evident in lateral view; cercus reniform, slightly exserted.

Female as in male except as follows: genitalia ( Fig. 17 View FIGURES 17 ­ 19 ) with vaginal furca shield­like, V­shaped, entirely sclerotized as a plate, with additional posterior bridge connecting long, thin lateral processes, medial process about one­third length of lateral processes; apical process well developed, subtriangular; spermathecal reservoir as in angusta , but basal membranous area tapering to apical duct shorter than in angusta ; apical duct relatively short, membranous, length about 1.5 length of reservoir; sperm pump fused basally; apical valve enlarged into glove­like membranous structure, median sperm pump shorter than lateral ones, with apical valve approximately 2 size of lateral ones; basal spermathecal duct and valve not evident; common duct strongly sclerotized.

Types. Holotype female from UNITED STATES: California: Riverside County: Whitewater, 29.iii. 1955, A.L. Melander, in USNM. Holotype examined during this study. The orangeish color of the humeral callus and postalar calli in the holotype is not natural, but instead due to a hypercyanic condition.

Remarks. Hall and Evenhuis (1986) recorded variation in the small yellow triangular spot behind the ocellar tubercle from present, to vague, to absent; reexamination of a long series of this and related species shows that the yellow occipital spot is always present in ostenta ; those specimens in which it is absent belong to other species. The mesonotal vittae can vary from thick to thin and almost incomplete between the interhumeral marks and the prescutellar area, but the latter case is very uncommon in the long series of specimens studied. The characters in the key should serve to distinguish virtually all of the specimens known thus far. Specimens have been collected between 5 April and 23 June, with most collected in late April and the middle of May.

Distribution. Previously known from California, Arizona, and Texas ( Hall and Evenhuis 1986). The following additional localities can be added to that distribution: UNITED STATES: Colorado: Walden. Utah: San Juan County: Abajo Mountains. MEXICO: Baja California Sur: 13 km S. Guillermo Prieto; 3.5 km WNW San Isidro; 13 km WNW La Purisima. Sonora: Ciudad Obregon. Further concentrated collecting may show it to also be found in New Mexico, Nevada, and possibly Chihuahua in northern Mexico.


Smithsonian Institution, National Museum of Natural History














Pieza ostenta (Melander)

Evenhuis, Neal L. 2002

Mythicomyia (Mythenteles) ostenta Melander. Hall & Evenhuis, 1986 : 339

Hall 1986: 339

Mythicomyia ostenta

Evenhuis 1983: 483
Hull 1973: 269
Painter 1965: 417
Melander 1961: 236