Pieza angusta (Melander) Melander, 2002

Evenhuis, Neal L., 2002, Pieza, a new genus of microbombyliids from the New World (Diptera: Mythicomyiidae), Zootaxa 36, pp. 1-28 : 6-9

Pieza angusta (Melander) , comb. nov.

Mythicomyia angusta Melander, 1961: 180 . Painter & Painter, 1965: 416. Evenhuis, 1983: 463.

Mythicomyia ministra Melander, 1961: 224 . Painter & Painter, 1965: 418. Evenhuis, 1983: 480. Syn. nov.

Mythicomyia (Mythenteles) angusta Melander. Hall & Evenhuis, 1986: 332 .

Mythicomyia (Mythenteles) ministra Melander. Hall & Evenhuis, 1986: 335 .

Mythicomyia vernalis Tabet & Hall, 1987: 50 . Syn. nov.

Male. Length: 0.82–1.23 mm. Head ( Fig. 5 ). Eyes dichoptic, separated at vertex by approximately 1.5 distance between lateral ocelli; front depressed medially, brownish yellow to yellow with spot of brownish black medially; face black, oral margin slightly paler; antenna black; scape minute; pedicel nearly as wide as long; first flagellomere ovoid, length 1.5–2.0 greatest width; second flagellomere short, about equal to width of first flagellomere; proboscis black, projecting beyond oral margin for distance from 0.5– 1.5 head height; occiput dull black to dark brown, with scattered pale hairs.

Thorax. Mesonotum dull black to dark brown; humeral callus, interhumeral triangle, lateral margin to wing base, postalar callus and (in some specimens) small spot above postalar callus yellow; interhumeral marks contiguous with humeral callus; dorsum with scattered inconspicuous minute dark hairs; scutellum brown to black; pleura predominantly black, yellow along notopleural suture and along medial longitudinal stripe; coxae and femora dark brown to black; apices of femora and tibiae yellow; hind tibia brown to dark brown; apical tarsal segments black; halter with stem and knob yellow.

Wing. Hyaline; veins brown; costa ends at just beyond end of vein R4+5; cell dm narrowed apically; vein at base of cell m1 subequal in length to r­m crossvein; otherwise venation as is typical for the genus.

Abdomen. Dorsum subshining dark brown to black; tergites II­VII with narrow yellow fascia on posterior margins, yellow color increasing in width on succeeding posterior segments, with scattered pale hairs; venter black with very narrow yellow fascia on posteriormargin of each segment.

Genitalia ( Fig. 7 ). In lateral view with gonocoxites long, thin, subtriangular, in ventral view subtrapezoidal with apical notch and small lateral button­like flange; gonostyli absent; gonocoxal apodemes flared apically, subtriangular­spatulate, strongly sclerotized at extreme apex; aedeagus long, thin, bifid apically; aedeagal apodeme subparallel and bent to large reniform apical portion, broadly vanes laterally, small vane dorsoapically; lateral rami large, subfoliate, slightly downcurved apically; epandrium subrectangular, rounded on anterior portion; pseudo­surstylus1 pointed, large; cercus hook­shaped, posterior end clubbed, anterior end spatulate, partially exserted.

Female as in male except as follows: genitalia ( Fig. 9 ) with vaginal furca V­shaped, thick, interrupted medially at vaginal orifice; lateral processes long, thin, slightly curved outward; spermathecal reservoir linear­ovate, darkly sclerotized on apical seven­eighths; apical spermathecal duct thin, membranous, length twice that of reservoir; sperm pump subequal in length to apical spermathecal duct, sclerotized on basal half, membranous on apical half, apical portion flared at apical valve, basal portion contiguous with common duct; basal valve not evident.

Types. Holotype male of angusta from UNITED STATES: California: Santa Barbara County: Carpinteria, 28.viii.1946, A.L. Melander. Holotype and paratype in the USNM examined during this study. The holotype of angusta differs from the description given in Hall and Evenhuis (1986) in that the male has dichoptic, not holoptic eyes. The type specimen has the eyes and head collapsed from drying, which gives the superficial appearance of holopticism.

Holotype female of ministra from UNITED STATES: Ca­ lifornia: San Diego County: Oak Grove, 9.v.1945, A.L. Melander. Holotype in USNM examined during this study.

Holotype male of vernalis from UNITED STATES: Cali­ fornia: Riverside County: Deep Canyon, 0.8 mi. N. Junction of Deep Creek and Horsethief Creek, 2960 ft., 9­16.v.1973, Ma­ laise trap, A.B. Tabet. Holotype in CAS. The holotype and a large amount of the type series has been examined during this study.

Remarks. Comparison of male genitalia of angusta , ministra , and vernalis shows considerable similarities of all the salient characters. Examination of a large series of all 3 spe­

cies and comparisons of male and female genitalia showed the three to be conspecific, thus the new synonymy above.

Study subsequent to that of Hall and Evenhuis (1986) has shown that there is some variation in the amount of sclerotization and the length of the sperm pump and some slight variation in the shape of the lateral sclerites of the vaginal furca of the female genitalia.

Specimens of this species have been collected in almost every month of the year. However, there does appear to be an apparent bivoltine occurrence of this species in the southern counties of California: a population from 24 April to 16 May, another from 29 July to 28 August, with the majority of specimens having been collected in late April and late August. Seven Mexican specimens from Sonora, Jalisco, and Tamaulipas were collected in January and February. Despite the temporal differences, all these Mexican specimens fall within the range of variation of the salient characters of this species.

Distribution. Hall and Evenhuis (1986) recorded angusta and ministra from California, Arizona, and New Mexico. I have examined conspecific specimens from these states plus the following additional localities in the UNITED STATES: Texas: Hidalgo County; and MEXICO: Baja California Sur: La Purisima; Miraflores. Jalisco: Puerto Vallarta. Sonora: Alamos. Tamaulipas: Manuel.

Figures

Figure 9. Pieza angusta (Melander), female genitalia.

FIGURES 5 ­ 6. Pieza heads, scanning electron micrographs. 5. Pieza angusta (Melander). 6. Pieza sinclairi, sp. nov.

FIGURES 7 ­ 8. Pieza male genitalia. 7. P. angusta (Melander); a. lateral view; b. epiphallic complex, dorsal view; c. gonocoxites, ventral view. 8. P. flavitibia, sp. nov.; a. lateral view; b. epiphallic complex, dorsal view; c. gonocoxites, ventral view.