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

description: Key to the species of New World Penthetria
Based on males (eyes holoptic). Females (eyes dichoptic) of some of these species are presently unknown (P. dolichopeza) or indistinguishable. To improve the efficiency of the identification process of specimens from USA and Canada proceed directly to couplet six (though females from USA / Canada are presently indistinguishable, they may be separated with relative confidence based on geographic distribution in areas where species appear to be allopatric (see distribution of species in Maps 2 & 3)).
1 Ventromedian lobes of posterior margin of gonocoxites strongly developed (Fig. 34, 45, vml) with ventromedian cleft often slightly deeper or more narrow in appearance due to stronger flanking lobes (Fig. 34 inset); gonostylus relatively slender in posterior view (Fig. 35) and apically acute; posterior margin of tergite nine with relatively shallow cleft, usually about one-third depth of tergite; tergite nine never deeply emarginate (over one-half length of tergite), shelf-like posteriorly (Fig. 10), or with a field of densely-set, short, black, spine-like setae on posteroventral edge of tergite (Fig. 5, sls); female with tergite nine well developed and strongly lobate posterolaterally (Fig. 54), cerci with second (ultimate) segment relatively short, and posteromedian lobes of sternite eight relatively broad (Fig. 55); South America..................... P. neonigrita Fitzgerald n. sp.
- Ventromedian lobes of posterior margin of gonocoxites weakly (Fig. 11, vml) to moderately (Figs. 20 & 25, vml) developed, sometimes entirely absent (Fig. 15); posteromedian cleft usually shallower and broader (Fig. 20, vmc) or entirely absent; gonostylus variable, but not slender in posterior view unless tergite nine deeply emarginate or gonostylus apically notched; tergite nine variable; female terminalia not with the above combination of characters; Canada to Central America.............. 2
2 Gonostylus glossy, shining, with long hairs basally, but only minute sparse hairs beyond base (Figs. 4–6, 9–11); tergite nine with posteromedian emargination deep, extending at least half, but usually more, the length of the tergite (Figs. 4–5, 9) and posteroventral edge bearing a field of densely-set, short, black, spine-like setae sharply contrasting typical setae on remainder of tergite (Fig. 5, sls; can be difficult to see in undissected specimens); tergite nine sometimes shelf-like posteroventrally (Fig. 10); apex of gonostylus broadly rounded (Figs. 9–11) or coming to a narrow rounded point (Fig. 5), never apically truncate or notched (Figs 16–20); females with second (ultimate) segment of cerci elongate and posteromedian lobes of sternite eight relatively narrow (Figs. 46–48); in both sexes vein R 2+3 sometimes with a basal appendix (Fig. 2, ba); Mexico and Central America............................................................................................ 3
- Gonostylus with long hairs basally as well as beyond base (e.g., Figs. 7–8); tergite nine without posteromedian emargination or with emargination more shallow and most often extending one-fifth to one-third the length of the tergite, but sometimes slightly over one-half the length of the tergite; vein R 2+3 without a basal appendix (e.g., Figs. 21, 23); tergite nine never shelf-like or with posteroventral edge with a field of densely-set, short, black, spine-like setae sharply contrasting typical setae on remainder of tergite; gonostylus variable; females with second (ultimate) segment of cerci shorter and posteromedian lobes of sternite eight broader (Figs. 49–53, 56) (females of these species indistinguishable except some by geographic range); widespread...... 4
3 Ninth tergum almost completely divided into two plates by posterior emargination (Fig. 9); posterior, inner (ventral) surface of ninth tergite developed into a pair of broad flat shelves when viewed posteriorly (Fig. 10); gonostylus broad and broadly rounded apically (Figs. 9–11); R 2+3 usually without, but sometimes with a basal appendix; female with sternite ten truncate/broadly rounded posteriorly? (as in Fig. 49; sternite 10 not visible in Fig. 48 as it is partly telescoped within preceding segments) (but see notes on this character in “Remarks” under P. appendicula).................................. P. distincta Hardy
- Ninth tergum not so deeply cleft (Fig. 4); posterior, inner (ventral) surface of ninth tergite not developed (or at most only very weakly developed) into a pair of broad flat shelves when viewed posteriorly (Fig. 5); gonostylus not as broad (Fig. 5); R 2+3 usually, but not always, with a basal appendix (Fig. 2); female (Fig. 3) with sternite ten tapered posteriorly to a rounded point? (Fig. 47) (but see notes on this character in “Remarks”)..................................... P. appendicula Hardy
4 Hind basitarsus, parallel-sided, very slender elongate (hind tibia only about 2.5 times as long as basitarsus; Fig. 12, hb); gonostylus short and stout with a distinct anteroapical thorn (Figs. 14–15); gonocoxite dorsally with an apical, medially-directed lobe just anterior to the gonostylar socket (Fig. 14, dal); ventromedian lobes of gonocoxites absent (Fig. 15); southern Mexico, Costa Rica ................................................................. P. dolichopeza Fitzgerald n. sp.
- Hind basitarsus usually robust to slightly swollen and sausage-shaped, sometimes more slender, but never slender and greatly elongated (Figs. 23, 30–31, hb); gonostylus not as above; gonocoxite dorsally without an apical medially-directed lobe just anterior to the gonostylar socket; ventromedian lobes of gonocoxites variable; widespread........................... 5
5 In dorsal and ventral views, divergent horn-like lobes of paramere more strongly projecting caudally and ventrally, often appearing apical (even though really more subapical in position) (Figs. 24–26, dlp), sometimes divergent lobes slightly less projecting (Figs. 28–29) making them barely visible or barely not visible in a strictly dorsal view, but in the latter case at least apex (most posterior aspect) of paramere slightly laterally compressed into a ridge so that apex appears more narrow (as an apical nubbin) in dorsal view rather than broadly rounded (Fig. 29); apex of gonostylus (Figs. 24–26, 28–29) usually broadly rounded or broadly rounded and culminating in an obtuse point medially, sometimes apically slightly truncate, but never with an apical notch; tergite nine uncleft or relatively shallowly cleft (up to about one-third its length) (Fig. 24); Mexico and Central America............................................................................ P. mexicana (Hardy)
- Divergent horn-like lobes of paramere not visible in dorsal view. In ventral view, divergent horn-like lobes less developed, not strongly projecting or appearing apical, but more collar-like and more confluent with posteroventral edge of paramere (Figs. 8 & 20, dlp); apex (most posterior aspect) of paramere rounded, dome-like in dorsal view, not laterally compressed into a narrow ridge/nubbin, and often with a minute notch (Figs. 7 & as in 16 & 20, p); gonostylus variable; Canada to Central America.. 6
6 Apex of gonostylus minutely truncate or with a small notch (the anterodorsal side of the notch often developed into a small point) (Figs. 16–20, 36–39); Canada, northwestern USA and USA east of the Rocky Mountains....................... 7
- Gonostylus apically broadly rounded or broadly rounded and culminating in an obtuse median point (Figs. 7–8) or, in some Mexican and Central American specimens gonostylus very slightly truncate apically (as in Fig. 19); Southern Arizona, USA south to Central America....................................................... P. arizonensis Fitzgerald n. sp.
7 In posterior view, gonostylus more robust (Fig. 40); in dorsal view, paramere more broadly rounded, less diamond-shaped (Fig. 38, p); USA & Canada east of the Rocky Mountains.......................................... P. heteroptera (Say)
- In posterior view, gonostylus more slender (Fig. 41); in dorsal view, paramere more diamond-shaped (Fig. 39, p); northwestern USA, widespread in Canada ........................................................ P. yakima Fitzgerald n. sp.
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 460-461, DOI: 10.11646/zootaxa.4926.4.1, http://zenodo.org/record/4529512