Penthetria mexicana  1937
Creators: name: Fitzgerald, Scott J.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Bibionidae
Penthetria
Penthetria mexicana

description: Penthetria mexicana (Hardy), 1937
(Figs. 23–29, 49, Map 4)
Type Material (examined). Holotype: Male (Fig. 23), point-pinned (BYUC), MEXICO: Guadalajara, 29 March 1934, S.E. Jones, 6528. Terminalia missing. Red label added: “ HOLOTYPE Plecia mexicanus Hardy det. S. Fitzgerald 2017.” Paratypes: MEXICO: same as holotype, 1F (“ allotype female”) (BYUC); Teotihuacan, 21 March 1934, S.E. Jones Coll., 1M (terminalia missing) (BYUC).
In the original description of P. mexicana (Hardy 1937; as Plecia mexicanus), three specimens, a male holotype and female allotype from the same locality and a male paratype from an additional Mexican locality are listed (see label data above). These specimens were stated to be deposited in the H.J. Reinhard collection (Hardy 1937, 1945). Three specimens matching the sexes and label data given by Hardy (1937, 1945) were found in the collection at BYUC with a hand written header label “ Plecia mexicanus n. sp.,” but without any additional labels indicating that these specimens represent the types of this species. However, because the sexes and label data match the original description, these specimens are here considered to be the types and have been labeled as such with red/blue “HOLOTYPE, ALLOTYPE, PARATYPE ” labels as appropriate and “det. S. Fitzgerald 2017” so it is clear that these specimens were identified as the types at a later date.
Though the male holotype and male paratype are missing the terminalia, Hardy’s drawings and original description (1937, 1945) indicate that the apex of the paramere has a distinctive pair of divergent points and the gonostylus is broadly rounded. Of the specimens I have examined, there is only one species that has this combination of characters. Additionally, material from the type locality (Guadalajara, Mexico) has been studied in order to accurately place this species.
Additional Material Examined. COSTA RICA: Hwy # 2 km 93, 83°45’W, 9°36’N, 1–7.IV.85, 3200 m, H. Goulet, L. Masner, 1M (CNCI); SAN JOSE: Villa Mills km 97, 14–16.II.1992, 3200 m, D.M. Wood, 3M (CNCI); GUATEMALA: GUATEMALA: Puerta Parada, 1850 m, J.C. Schuster, 27 June–4 July 2015, 1M (SFC), 11–18 July 2015, 1M (SFC), 19–26 Oct 2013, 1M (SFC), 2–9 XI 2013, 3M, 2F (SFC); Puerta Parada, 1840 m, J.C. Schuster, 4– 11 XI 2017, 6M (4 SFC, 2 UVGC), 28 Oct–4 Nov 2017, 1M (SFC); MEXICO: “ Mex.,” 2M (USNM); HIDALGO: 34 mi. NE Jacala, 15 VII 1964, E.M. Fisher, 1M (NHMLA); JALISCO: Guadalajara, Crawford, 1M (USNM); Villa Corona, 14 April 1977, Davis & Hanson, 5M (NHMLA); MEXICO: 29 Aug 1922, E.G. Smyth, 1M (USNM); Ixtapan de la Sal, 16-X-1996, R. T. Ballstaedt, 1M (BYUC); MEXICO CITY: D.F., J. R. Inda, 1M (USNM); D.F., Coapa, 29 Aug 1922, E.G. Smyth, 1M (USNM); Mexico City, I-4-1915, Mx 10, R. H. Van Zwalenburg, 1M (USNM); MICHOACAN: Patzcuaro, 20 Aug 1976, Hanson, Schwartz, 4M (NHMLA); OAXACA: Oaxaca, 27 May 1900, C.C. Deam, 1M (USNM); SAN LUIS POTOSÍ: “Tamasopa” [= Tamasopo?], XII.4.09, F.C. Bishopp, 1M (USNM); VERACRUZ: Cordoba, F. Knab, 20 Dec 07, 1M, 1F (in copula) (USNM), 23 Dec 07, 1M (USNM), 24 Dec 07, 1F (USNM); Cordoba, VII-13-1966, 3M, 1F (SFC); Jalapa, 1–6.VIII.61, R.& K. Dreisbach, 1M (CNCI), 1M (USNM); Jalapa, 9/28–X/3/61, R.& K. Dreisbach, 2M, 4F (USNM); Orizaba, 2500’, II-13-54, R. R. Dreisbach, 2M (USNM); Rio Blanco, II-13-57, R.& K. Dreisbach, 1M (USNM); Orizaba, 9–16 Jan ’92, H. Osborn, 1M, 2F (USNM).
Diagnosis. Males of P. mexicana can be distinguished from all New World congeners by the following combination of characters: divergent horn-like lobes (whale-tail-like structure) of paramere strongly projecting caudally and ventrally, often appearing nearly apical when viewed dorsally or ventrally (Figs. 24–26) though in some cases where slightly less projecting (Figs. 28–29) and slightly visible or barely not visible in strict dorsal view, apex of paramere slightly laterally compressed forming a narrow ridge or nubbin (Fig. 29), apex of gonostylus (Figs. 24–26, 28–29) broadly rounded, broadly rounded and culminating in an obtuse median point, or apically truncate (though never with an apical notch), ventromedian lobes of gonocoxite weakly to moderately developed (Fig. 25, vml), and posterior margin of tergite nine (Fig. 24) virtually uncleft (flat) to cleft about one-third its length, without shelf-like development or field of densely-set, short, black, setae on posterior edge.
Remarks. P. mexicana is most similar to P. arizonensis, but can be distinguished by the structure of the paramere as described above. While the pair of divergent lobes of the paramere are also distinctly present in P. arizonensis (as well as most of the other species studied), in this species the lobes are never strongly developed, never apical when viewed ventrally or dorsally, and are more collar-like and confluent with the dome-like contours of the paramere (Fig. 8, dlp). Furthermore, the paramere is broadly rounded in P. arizonensis (often with a small groove as in P. heteroptera, Fig. 16). In some specimens of P. mexicana studied from Central America where the divergent lobes of the paramere are less dramatic (are slightly less projecting and are barely not visible in a strictly dorsal view), the apex of the paramere in P. mexicana is slightly laterally compressed into a ridge or nubbin rather than broadly rounded with a groove as in P. arizonensis.
Females of P. mexicana (Fig. 49) are indistinguishable from P. arizonensis, which they are sympatric with over much of their range, but they can be distinguished from P. appendicula and P. distincta, which have more slender lobes on sternite eight and the second segment of the cerci more elongate (Figs. 46–48), and from P. neonigrita, which has a strongly developed tergite nine (Fig. 54).
Wing length in P. mexicana ranges from 5.5–8.0 mm (n=5) in males and is about 8.0 mm (n=1) in females. Geographic & Seasonal Distribution. Mexico and Central America (Map 4). 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 476-479, DOI: 10.11646/zootaxa.4926.4.1, http://zenodo.org/record/4529512