Penthetria arizonensis Fitzgerald 2021, n. sp.
Creators: name: Fitzgerald, Scott J.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Bibionidae
Penthetria
Penthetria arizonensis

description: Penthetria arizonensis Fitzgerald n. sp.
(Figs. 7–8, 32, 52–53, 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), 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); 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); 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); ZACATECAS: Rio Grande, X-18-68, G.E. Bohart, 1M (NHMLA).
Description (based on specimens from Arizona, USA). Male (Fig. 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). Abdomen. Dark brown to black. Terminalia (Figs. 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) to moderately (as in Fig. 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): 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), 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). 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), 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), 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). In some specimens of P. mexicana where the divergent lobes of the paramere are slightly less projecting (Fig. 28) or even slightly out of view from a strict dorsal view (Fig. 29), the apex of the paramere is slightly laterally compressed making it narrow and ridge/nubbin-like apically (Fig. 29), whereas the paramere of P. arizonensis is broadly rounded (Fig. 7) and often has a small groove apically (as in Figs. 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), and from P. neonigrita, which has a more strongly developed tergite nine (Fig. 54).
Etymology. The specific epithet is taken from the type locality, Arizona, USA.
Geographic & Seasonal Distribution. Southern Arizona, USA south to Central America (Map 2). Seasonal distribution summarized in Table 1.
description: Published as part of Fitzgerald, Scott J., 2021, Penthetria Meigen (Diptera: Bibionidae): Revision of the New World species and world catalog, pp. 451-500 in Zootaxa 4926 (4) on pages 463-467, DOI: 10.11646/zootaxa.4926.4.1, http://zenodo.org/record/4529512