Penthetria arizonensis Fitzgerald

Fitzgerald, Scott J., 2021, Penthetria Meigen (Diptera: Bibionidae): Revision of the New World species and world catalog, Zootaxa 4926 (4), pp. 451-500: 463-467

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Penthetria arizonensis Fitzgerald

n. sp.

Penthetria arizonensis Fitzgerald   n. sp.

( Figs. 7–8 View FIGURES 7–8 , 32 View FIGURES 30–32 , 52–53 View FIGURES 50–53 , Map 2 View MAP 2 )

Type Material. Holotype: Male, point-pinned ( USNM), USA, ARIZONA, Cochise Co., near Benson , 21 Sept. 1985, J. Jenkins coll. [white label]   / HOLOTYPE, Penthetria arizonensis Fitzgerald   [red label]. Terminalia dissected. Paratypes: USA: ARIZONA: Same data as HT, 3M ( CSUC)   ; Ramsey Cyn. 5200’, 15 mi S. Sierra Vista, Huachuca Mts. 12. VI.1967, R. F. Sternitzky, 2M ( CNCI)   ; Ramsey Cyn., 5000’, 15 mi S. Sierra Vista, Huachuca Mts., Malaise trap, Sternitzky , 3. VI.1967, 1M ( CNCI)   , 4. VI.1967, 1M ( CNCI)   ; Santa Cruz Co., Duquesne Rd. at jct. FS4675, 17–30 Sept 2018, V-FIT, 31.3771°, -110.7593°, W.B. Warner, 4M (2 SFC, 2 ASUT)   ; Cochise Co., Bisbee, 1429 Franklin St. , 1585 m, A.S. Menke , MT, 31°24’23”N, 109°55’57”W, 28.ix–1.x.2012, 3M ( SFC) GoogleMaps   , 2–7.x.2012, 3M ( SFC)   , 10–16.ix.2012, 6M, 1F ( SFC)   , 16–24.ix.2012, 5M ( SFC)   , 1M ( BYUC).

Additional Material examined. GUATEMALA: GUATEMALA: Puerta Parada , 1850 m, 7–14 IX 2013, J.C. Schuster, 1M ( UVGC)   , 22–28 Aug 2015, 1M, 2F ( SFC)   ; COSTA RICA: SAN JOSÉ: San Pedro de Montes de Oca, 11.X.33, C.H. Ballou , on cabbage, C. R. No. 1872, 1M ( USNM)   ; MEXICO: CHIAPAS: 7200 ft., S. Crist. las Casas , 10 June 1969, Malaise Trap, 3M ( CNCI)   ; MEXICO CITY: D.F., Sept ’98, 2M ( USNM)   ; MICHOACAN: El Salto, 5 mi. W., X.9.1964, A.E. Michelbacher , 1M, 1F (in copula) ( SFC)   ; MORELOS: 6 mi E Cuernavaca , 12 Sept 1973, W.J. Hanson, B.A. Haws, 2M, 2F ( NHMLA)   ; Cuernavaca , 9-28-57, R. & K. Dreisbach, 1M ( CNCI)   ; PUEBLA [?]: Puebla Rd., km 63, x-2-57, Dreisbach , 4M ( CNCI)   ; SONORA: Alamos Rancho Acosta, MT in dry wash, tropical deciduous forest, 28.ix–3.x.2006, M.E. Irwin, 395 m, 27°01.57N, 108°55.37W, 1M ( SFC) GoogleMaps   ; 27 km NE Alamos, Rancho Santa Barbara, La Posa de Encino Boludo , MT at isolated water hole in oak woodlands, 20–27.ix. 2008, 1242 m, M.E. Irwin & F.D. Parker, 27°06.27N, 108°43.86W, 1M ( SFC) GoogleMaps   ; 37 km NE Alamos, Rancho santa Barbara , malaise, dry wash in oak-pine forest, 2–6.x.2006, M.E. Irwin, 1295 m, 27°06.60N, 108°43.91W, 1M ( SFC) GoogleMaps   ; ZACATECAS: Rio Grande , X-18-68, G.E. Bohart, 1M ( NHMLA)   .

Description (based on specimens from Arizona, USA). Male ( Fig. 32 View FIGURES 30–32 ). Body length: approx. [5.0] mm. Head. Black. Compound eye holoptic, covering virtually all of dorsal and lateral surface of head, with lateral longitudinal step dividing upper and lower portion of eye. Eyes nearly bare, with some very minute, very sparse ommatrichia present.Antennae black, eight to nine flagellomeres with black setae. Flagellomeres wider than long except first and ultimate flagellomeres about as wide as long. Three ocelli on well-developed tubercle. Thorax matte dark brown to blackish with light brown highlights on humeral ridge and posterior portions of pleurae, sometimes with mesonotum dark brown with three broad black longitudinal stripes, the median stripe reaching the pronotum and the lateral stripes truncated anteriorly. Thorax largely bare except fine short dark hairs on mesonotum in broad dorsocentral rows and a few hairs anterolaterally. Scutellum bare or with a few sparse short fine dark hairs and middle of katepisternum and metepisternum with long dark hairs. Legs. Slender, entirely dark brownish-black with dense short dark appressed hairs. Hind femur slightly thickened (clavate) on apical third. Hind tibia slender elongate gradually thickened apically. Hind basitarsus robust to slightly swollen and sausage-shaped, about four times as long as wide. Wings. Arizona specimens ca. [5.0]–6.0 mm (n=7) and Mexican and Central American specimens slightly larger 7.0–8.0 mm (n=3), brown fumose, darker costally. Veins brown, pterostigma concolorous with membrane. Venation as in other members of the genus. Sc long, complete. R 2+3 elongate, subparallel to R 4+5, without basal appendix. CuA and CuP apically convergent, sometimes reaching wing edge independently (not meeting), sometimes meeting prior to wing edge forming a closed cell cua ( Fig. 32 View FIGURES 30–32 ). Abdomen. Dark brown to black. Terminalia ( Figs. 7–8 View FIGURES 7–8 ) dark brown to black. Tergite nine broader than long, posterior margin with shallow emargination reaching about one-third to slightly less than one-half the depth of sclerite. In dorsal view, gonocoxites dorsoapically without small apically rounded medially-projecting lobe just dorsal to gonostylar socket (as found in P. dolichopeza   ). In ventral view, posterior edge of medially fused gonocoxites + hypandrium with a broad shallow median cleft bounded by a pair of weakly ( Fig. 8 View FIGURES 7–8 ) to moderately (as in Fig. 20 View FIGURES 16–20 ) developed lobes. In dorsal and ventral views, gonostylus stout, gently curved, apically broadly rounded or broad and culminating in a very obtuse point medially (in one paratype from Arizona point is more distinctive and in some Mexican and Central American specimens the apex of gonostylus slightly truncate due to a flat area between the median point and a minutely developed dorsoapical point). Paramere indistinguishable from P. heteroptera   ; in dorsal and ventral views fused parameres projecting from out of genital capsule, shiny brown heavily sclerotized dome-like, often with a small cleft apically. Divergent horn-like lobes of paramere present, but ventral and subapical in position and more confluent, with the dome-like contours of the paramere rather than strongly projecting caudally and ventrally as found in P. mexicana   . Cerci fleshy, apically rounded with setae.

Female. Similar to male. Body about 5.0 mm and wing 5.5–6.0 mm (n=2; Arizona). Eyes dichoptic. Antennae with unknown number of flagellomeres (Arizona female missing antennae). Female hind basitarsus slender elongate. Abdomen stout. Terminalia ( Figs. 52–53 View FIGURES 50–53 ): Tergite nine present as narrow, transverse strap, medially subdivided into two sclerites; more produced ventrolaterally. Tergite ten minute, nearly hyaline, longitudinally elongate, lying between bases of cerci. Cerci two-segmented, apical segment relatively short. Subgenital plate (= sternite eight) large, longitudinally subdivided, with posterior margin with a pair of broad lobes. Y-shaped genital fork present. In addition to genital fork, a minute pair of sclerites present between the posterior margin of the subgenital plate and the anterior margin of sternite ten. Sternite 10 present, posteriorly broadly rounded. Three rounded, sclerotized, capsule-like, spermathecae present.

Diagnosis. Males of P. arizonensis   can be distinguished from the very similar species P. heteroptera   and P. mexicana   by the gonostylus without an apical notch and apex of paramere broadly rounded (see detailed discussion and comparsion of these three species in “Remarks”).

Remarks. Historically all specimens of Penthetria   from the USA were considered to be P. heteroptera   . However, specimens from southern Arizona (previously determined as P. heteroptera   by various workers including the present author) represent a distinct species ( P. arizonensis   ). Within the USA, allopatric populations of P. heteroptera   (East of the Rocky Mountains) and P. arizonensis   (southern AZ) are easily distinguished based on differences in the apex of the gonostylus; P. heteroptera   has the apex of the gonostylus minutely truncate, the truncate portion often slightly notched ( Figs. 16–20 View FIGURES 16–20 ), with the anterodorsal side of the notch often produced into a small point, while the Arizona specimens studied all have the apex of the gonostylus broadly rounded or broadly rounded and culminating in an obtuse median point ( Figs. 7–8 View FIGURES 7–8 ). While these morphological differences and the correlated allopatric distribution seem to indicate two distinct species, the study of Mexican and Central American specimens attributed to P. arizonensis   revealed variation in the apex of the gonostylus (the broadly rounded apex is sometimes very minutely truncate (as in Fig. 19 View FIGURES 16–20 ), though never notched), which make these specimens, in some cases, indistinguishable from some specimens of P. heteroptera   from the eastern USA that have only a very slight truncation and lack a notch. It is unclear whether the slightly truncate gonostylus in P. arizonensis   is simply intraspecific variation or if there is some integration between the two species, but as no definitive specimens of P. heteroptera   (gonostylus with an apical notch) have been studied from south of the USA (either in this study or by Hardy (1945)) and the fact that P. mexicana   also sometimes has the gonostylus slightly apically truncate, the conclusion adopted here is that of intraspecific variation. Regardless of this inability to reliably distinguish some Mexican and Central American specimens from some eastern North American specimens, the two forms have been treated as distinct species; P. heteroptera   east of the Rocky Mountains in USA and Canada and P. arizonensis   from southern Arizona, USA to Central America. P. arizonensis   likely represents the species identified by Hardy (1945) as P. nigerrima (Bellardi)   , which was originally described from Mexico (see “Unrecognized Species of Penthetria   ” below).

In addition to P. heteroptera   , P. arizonensis   is also very similar to P. mexicana   , as they share the apically broadly rounded gonostylus which sometimes culminates in an obtuse median point or may be apically truncate. P. arizonensis   is most easily distinguished from P. mexicana   by the structure of the paramere; in P. mexicana   the pair of divergent horn-like lobes (whale-tail-like structure) often appears apical (most posterior) when the paramere is in dorsal or ventral views ( Figs. 24–26, 28 View FIGURES 24–29 ), while in P. arizonensis   the divergent lobes of the paramere do not appear apical when viewed ventrally or dorsally, are more ventral and subapical in position, and are more confluent with the dome-like contours of the paramere rather than strongly projecting caudally ( Figs. 7–8 View FIGURES 7–8 ). In some specimens of P. mexicana   where the divergent lobes of the paramere are slightly less projecting ( Fig. 28 View FIGURES 24–29 ) or even slightly out of view from a strict dorsal view ( Fig. 29 View FIGURES 24–29 ), the apex of the paramere is slightly laterally compressed making it narrow and ridge/nubbin-like apically ( Fig. 29 View FIGURES 24–29 ), whereas the paramere of P. arizonensis   is broadly rounded ( Fig. 7 View FIGURES 7–8 ) and often has a small groove apically (as in Figs. 16 & 20 View FIGURES 16–20 ); the paramere of P. arizonensis   is indistinguishable from that of P. heteroptera   .

Females of P. arizonensis   are indistinguishable from females of P. heteroptera   , P. mexicana   and P. yakima   , but they can be distinguished from P. appendicula   and P. distincta   , which have more slender posteromedian lobes on sternite eight and the second segment of the cerci more elongate ( Figs. 46–48 View FIGURES 46–49 ), and from P. neonigrita   , which has a more strongly developed tergite nine ( Fig. 54 View FIGURES 54–57 ).

Etymology. The specific epithet is taken from the type locality, Arizona, USA.

Geographic & Seasonal Distribution. Southern Arizona, USA south to Central America ( Map 2 View MAP 2 ). Seasonal distribution summarized in Table 1.


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