UDC 595.773.4
A New Species of the Genus Plagiocephalus 
(Diptera, Ulidiidae) from Central America
E. P. Kameneva

This e-paper is distributed as an example and does not consist a publication in the sense of the Code

I. I. Schmalhausen Institute of Zoology, National Academy of Sciences of the Ukraine, 
B. Khmelnitski str. 15 UA01601 Kiev Ukraine
E-mail: kameneva@entom.freenet.kiev.ua
Received
A New Species of the Genus Plagiocephalus (Diptera, Ulidiidae) from Central America. Kameneva E. P. —Plagiocephalus intermedius Kameneva sp. n. from Costa Rica is described. It differs from two other species by shorter eye stalks and pattern, venation and shape of the wing in male and head coloration and wing venation in female. A key to species of the genus Plagiocephalus Wiedemann is provided. The lectotype of Achias lobularis Wiedemann is designated.
Key words: Diptera, Ulidiidae, Central America, new species.
Новый вид рода Plagiocephalus (Diptera, Ulidiidae) из Центральной Америки. Каменева Е. П. — Описан Plagiocephalus intermedius Kameneva sp. n. из Коста-Рики, который отличается от других видов рода более короткими стебельками глаз, а также рисунком, жилкованием и формой крыла самца и окраской головы и жилкованием крыла самки. Приведена таблица для определения видов рода Plagiocephalus Wiedemann. Обозначен лектотип Achias lobularis Wiedemann.
Ключевые слова: Diptera, Ulidiidae, Центральная Америка, новый вид. 
Новий вид роду Plagiocephalus (Diptera, Ulidiidae) з Центральної Америки. Каменєва О. П. — Описано Plagiocephalus intermedius Kameneva sp. n. з Коста-Ріки, який відрізняється від інших видів роду коротшими стебельцями очей, а також візерунком, жилкуванням і формою крила самця та забарвленням голови і жилкуванням крила самки. Наведено таблицю для визначення видів роду Plagiocephalus Wiedemann. Позначено лектотип Achias lobularis Wiedemann.
Ключові слова: Diptera, Ulidiidae, Центральна Америка, новий вид.

Introduction
Plagiocephalus Wiedemann is a peculiar genus of the family Ulidiidae. Males of all species have stalked eyes (fig. 1). The genus has been revised by Steyskal (1963, 1964, 1968). However, while treating material of collection of the Instituto National de Biodiversidad (Santo Domingo, Costa Rica), some uncommon specimens certainly belonging to this genus attracted my attention. The study of numerous additional material (including types) from the museums listed below, as well as descriptions and figures of nominal species ever assigned to Plagiocephalus (including already synonymized), has shown that a series of specimens from Costa Rica (both males and females) belonging neither to Plagiocephalus lobularis Wiedemann nor P. latifrons (Hendel) represents a new undescribed species. Also, while preparing the catalogue of the family Ulidiidae of the World, some nomenclatural inconsistencies needed correction were noted in previous publications.
This study is based upon material deposited in the following collections: DEI — Deutsche Entomologisches Institut, Zentrum für Agrarlandschafts- und Landnutzungsforschung, Eberswalde, Germany; HMNH — Hungarian Natural History Museum (Természettudományi Muzeum), Budapest; INBio — Instituto Nacional de Biodiversidad, Santo Domingo, Heredia, Costa Rica; INBio OET — material possessed by the “OET” Project deposited in INBio; MLUH — Institut für Zoologie, Martin-Luther-Universität Halle-Wittenberg, Halle-am-Saale, Germany; MTD — National Museum of Zoology (Staatliches Museum für Tierkunde), Dresden, Germany; NHMLA — Natural History Museumof Los Angeles County, USA; NHMW — Natural History Museum of Vienna (Naturhistorisches Museum Wien); UG — Department of Environmental Biology, University of Guelph (Canada); USNM — United States National Museum of Natural History, Washington, D. C.; ZMHB — Museum of Natural History of the Humboldt University in Berlin (Museum für Naturkunde der Humboldt-Universität zu Berlin); ZMUC — Zoologisk Museum, Universitets Copenhagen, Denmark.
Morphological terminology follows J. F. McAlpine (1981).
Plagiocephalus Wiedemann, 1830
Wiedemann, 1830 b: 12; Westwood, 1849: 235; Osten-Sacken, 1881: 478; Hendel, 1911: 4, 52; Cresson, 1923: 258; Frey, 1926: 47; Carrera, I950: 261; Aczél, 1951: 421; Steyskal, 1963: 511; 1964: 400; 1968: 54.21.
Type species: Plagiocephalus lobularis Wiedemann, 1830: 15 (by monotypy).
Stylophthalmyia Frey, 1926: 45 (synonymized by Steyskal, 1963).
Type species: Stylophthalmyia fascipennis Frey, 1926: 46 (by original designation).
Ophryoterpnomyia Hendel, 1936: 76 (synonymized by Carrera, 1950).
Type species: Terpnomyia latifrons Hendel, 1909a: 18 (by original designation).
Paragoniaeola Blanchard, 1938a: 370 (synonymized by Aczél, 1951). 
Type species: Paragoniaeola tanycephala Blanchard, 1938a: 371 (by original designation).
Eupterocerina Blanchard, 1938b: 91 (synonymized by Steyskal, 1968). 
Type species: Eupterocerina conjucta Blanchard, 1938b: 91 (by original designation).
Willineria Blanchard, 1951: 32 (synonymized by Steyskal, 1964).
Type species: Willineria orfilai Blanchard, 1951: 32 (by original designation).
Plagiocephala: Macquart, 1843: 213; Loew, 1873: 26; Hendel, 1909b: 47 (unjustified emendation).
Plagiocephalas: Frey, 1926: 47 (error).

Diagnosis. Head transverse in both sexes, its shape sexually dimorphic: in males, strongly widened head with stalked eyes and frons much wider than long, while in females, only moderately widened (at least most twice as wide as long). Body brownish to black with pattern of sparsely yellowish-grey microtrichose spots and bands; mesonotum with brown microtrichose pattern, without dots at bases of setulae; proepisternal seta well-developed; 1 supraalar and 2 dorsocentral setae. Wing hyaline with dark banded pattern; vein R1 setulose in apical half, in male not bowed posteriorly; R2+3 almost straight; R-M at apical 2/5 of discomedial cell; cell bcu with short postero-apical lobe. Abdominal tergites 3–5 subequal long in both sexes. Male genitalia: phallus bare, extremely elongated; ejaculatory apodeme with apical portion at least as long as its fan-like portion, elliptic epandrium similar to that in Rhyparella Hendel and Dasymetopa Loew: medial surstylus bears 2 equal subapical prensisetae in P. latifrons (Hendel). Abdominal sternites of females 4–6 without apodemes; tergite 6 short, hidden under tergite 5, with several short marginal setulae; aculeus long and narrow; cercal unit elongate oval.
 
Key to species of Plagiocephalus
Таблица для определения видов Plagiocephalus
1. Face wholly pale yellow or brownish; eyes stalked; wing sometimes lobate (males) ............. 2
— Face with large black spot between antennae; eyes not stalked, wings of normal outline (females) ............ 4
2. Wing with three scallop-like lobes at base of posterior margin; crossband running through vein R-M widely connected with oblique subbasal band (fig. 1, 2) ............ lobularis Wiedemann
— Wing of normal outline; crossband through vein R-M at most barely touching oblique subbasal band............ 3 
	3. Eye span (< 7,1 mm) almost equal to length of body or wing; vein R-M proximally of R1 apex (fig. 1, 3) ............ ............. intermedius Kameneva, sp. n.
— Eye span (> 7,9 mm) much greater than length of body or wing; vein R-M at level of R1 apex (fig. 1, 1) ..............................................................…….....… latifrons Hendel
	4. Parafacial between antenna and eye distinctly blackened (fig. 2, 4); vein R-M at level of R1 apex (fig. 2, 1) ...................................................................……..... latifrons Hendel
— Parafacial between antenna and eye yellow (fig. 2, 5); vein R-M proximally of vein R1 apex (figs. 2, 2–2, 3) ........... 5
5. Crossband running through vein R-M well connected with oblique subbasal band (fig. 2, 2) ...................................................................……..... lobularis Wiedemann
— Crossband running through vein R-M not or barely touching oblique subbasal band (fig. 2, 3). .................. ........... intermedius Kameneva, sp. n.
Plagiocephalus lobularis (Wiedemann, 1830) (figs. 1, 2; 2, 2)
Wiedemann, 1830 a: 555; Macquart, 1835: 260 (Achias); Wiedemann, 1830 b: 15; Westwood, 1849: 235; Frey, 1926: 47; Carrera, 1950: 262; Aczél, 1951: 422; Hennig, 1952: 616; Steyskal, 1963: 512; 1968: 54.21 (Plagiocephalus); Macquart, 1843: 213; Hendel, 1909 b: 47 (Plagiocephala). — Paragoniaeola tanycephala Blanchard, 1938a: 371 (synonymized by Aczél, 1951). — Eupterocerina conjuncta Blanchard, 1938b: 91 (synonymized by Steyskal, 1968). — Ophryoterpnomyia zikani Capoor, 1954: 205 (synonymized by Steyskal, 1963). — Plagiocephalus latifrons: Carrera, 1950: 265 (?misidentification; see Steyskal, 1963).
Material. Type. Lectotype (here designated) #: “P. lobularis / Wied. / Brazils / Lund”, “Mus. Westerm.”, “Syntype # / Achias lobularis / Wiedemann / 1830 / des. V. Korneyev / XII.2003” (ZMUC). 
Non-type. Brazil: Santa Catharina, “Bez. Humboldt / W. Ehrhardt / vend.”, 1.11.1910, # (DEI); ibidem, “Nova Teutonia”, 10.05.1954, $, 11.08.1955, $ (Plaumann) (ZMHB); San Paulo, Santos, 24.01.94, # (MLUH); “Maracau / M. Grosso”, 02.1937, $; Rio de Janeiro, 10.1938, 11 $ (Shannon) (USNM); Paraguay: Hohenau, 250 m, 25.10.1907, $ (DEI); ibidem, 25, 26.10.1907, 2 $ (MTD); Argentina: Misiones, Iguazu, 4–10.10.1927, # (Shannon) (USNM).
Comments. This species is well known from complete descriptions including excellent figures (male: Wiedemann, 1830 b; Blanchard, 1938 a; female: Blanchard, 1938 b; Capoor, 1954; both sexes: Carrera, 1950). Female terminalia were studied and briefly described and figured by Capoor (1954: 207). Revised distributional range includes southeastern and southern Brazil, Paraguay and Argentina. P. lobularis differs from other species of the genus by the following characters: crossband running through vein R-M well connected with oblique subbasal band and vein R-M proximally of vein R1 apex in both sexes; wing of male with three scallop-like lobes at base of posterior margin; the eye span in male less than in P. latifrons; parafacialium of female between antenna and eye completely yellow.
Dr. Valery Korneyev kindly examined the Wiedemann’s collection at the ZMUC on my request, but has not found any specimens of this species. Instead, there was a male specimen in the general collection, which fits well the original description (Wiedemann, 1830 a) and figure (Wiedemann, 1830 b) in position of certain pale spots and other individual features. It belonged to Lund’s collection and was collected in Brazil, as it was originally noted in the description. As this species was described from an unknown number of males (one male? more?), we considered the specimen depicted by Wiedemann and now deposited in the ZMUK collection a syntype. According to my own observations, there are no additional specimens of this species from Wiedemann’s collection neither in Vienna nor in Frankfurt. Herewith, I designate it as the lectotype of Achias lobularis Wiedemann to avoid further uncertainty. 
Plagiocephalus latifrons (Hendel, 1909) (figs. 1, 1; 2, 1; 2, 4)
Hendel, 1909 a: 18; 1909 b: 31; pl. 2, figs. 30, 31 (Terpnomyia); Hendel, 1936: 76 (Ophryoterpnomyia); Aczél, 1951: 421; Steyskal, 1963: 512; 1964: 400; 1968: 54.21 (Plagiocephalus). — Stylophthalmyia fascipennis Frey, 1926: 46 (synonymized by Steyskal, 1963). — Willineria orfilai Blanchard, 1951: 32 (synonymized by Steyskal, 1964). 
Material. Type. Syntypes of Terpnomyia latifrons: 4 $: “Bolivia - Mapiri / 21.I.03 / S. Carlos 800 m”, “Terpnomyia latifrons / det. F. Hendel”, “Cotypus”; Bolivia - Mapiri / 5.III.03 / Sarampioni 700 m”, “Terpnomyia latifrons / det. F. Hendel”, “Cotypus”; “Peru - Urubambafl. / 10.IX.03 / Umahuankilia”, “Terpnomyia latifrons / det. F. Hendel”, “Cotypus” [Garlepp] (Coll. Schnuse) (MTD); “Peru - Urubambafl. / 13.IX.03 / Umahuankilia”, “Terpnomyia latifrons / det. F. Hendel”, “Paratype”, “Coll. Hendel” [Garlepp] (NHMW).
Non-type. Mexico: Chiapas, Cacahcatan, 30.08.1967, 3 $ (Sancae); Guatemala: Escuinta: Pafin, 1992, #, $ (Lopez); Salvador: “La Union”, “GRS”, 25.01.1957, #, 2 $; “Santa Tecla”, $; Honduras: La Ceiba, 7.04.1916, $; Nicaragua: Masaya, La Concha, 7.02.1961, # (USNM); Costa Rica: Alajuela: San Ramón, Angeles, R. B. San Ramón, 1100 m, 23.01-23.02.1995, $ (Carballo); Fca San Gabriel, 2 km SW Dos Rios, 600 m, 05.1989, $ (GNP Biodiv. Survey); Puesto Quebradón, Guatuzo, P. N. Tenório, 300 m, 05.1989, $ (Rodrigues) (INBio); Volcán Tenório, Bijagua Biol. Sta., 700 m, 20.06.2000, $ (Buck) (UG); San Mateo, Higuito, $; Cartago: La Suiza, 2 $ (AL Melander Collection) (Schild) (USNM); Heredia: Est. Biol. La Selva, 50-150 m, 1.04.1993, 2.03.1993, 1.07.1993, 3 $ (INBio OET); Guanacaste: Tierras Morenas, 700 m, 01.1994, 2 #, 3 $; ibidem, 685 m, 09.1993, #; ibidem, 02.1994, # (Rodrigues); Guan. PNSR, Bosque Humedo, 300 m, 5–6.04.1997, # (Zumbado); ibidem, 07.1999, 2 $ (Sullivan, Pérez); ibidem, 11.1999, $ (Janzen); Limón: A. C. Amistad, R. B. Hitoy Cerere, Valle de la Estrella, 300 m, 13.05-15.06.1994, 5 $ (Carballo); ibidem, 140 m, 17.06-17.07.1999, 2 $ (Umafia); Sendero Bobócara, 140 m, 17.06-17.07.1999, $ (Umafia); 300 m, 11.10-11.11.1999, $ (Umafia); ibidem, 17.02–17.03.2000, $ (Umafia); Valle del Selencio, Sendero Toma de Agua, 100-140 m, 05-06.2000, $ (Umafia); (INBio); Estrella Valley, Pandora, 28.03.1984, 4 $ (Manley) (UG); Puntarenas: Coto Brus, Est. Pittier, Rio Gemelo, 700 m E de la Estacion, 1600 m, 8–19.09.1997, # (Moraga); P. N. Manuel Antonio, Quepos, 80 m, 10.1993, # (Varela); 50 m R. B. Carara, Est. Quebrada Bonita, 09.1989, $ (Zúniga); Osa: Golfito, P. N. Corcovado, Sendero a Rio Claro, 1–100 m, 17.06–4.09.1991, $ (Saborio); ibidem, Sendero a Sirena, 100 m, 15.05-15.06.2000, $ (Azofeifa); ibidem, Est. Sirena, 1-100 m, 06.1990, $ (Maass); Rancho Quemado, 200 m, 01.1991, $ (Quesada) (INBio); Golfito, 22.07.1957, 2 $ (Truxal, Menke) (NHMLA); Piedras Blancas, 24 km W, 200 m, 11.1990, $ (Hanson) (USNM); Panama: Barro, Colorado Isl., 01–03.1944, # (Zetek); ibidem, 10–17.05.1964, # (Duckworth); El Cermeno, 12.1939–01.1940, # (Zetek); TRINIDAD: Simpla., Akima - Blanchisseuse Rd., 20.07.1975, # (Price); Venezuela: Lara, 4 km NW of La Pastora, 2–3.03.1978, # (Hoppner); T. F. Amaz., Cerro de la Neblina, Basecamp, 140 m, 21–29.02.1984, $ (Davis, McCabe); ibidem, 10–20.02.1985, $ (Spangler, Faitoute, Steiner) (USNM); Brazil: “Unt. Amaz. Taperinha b. Santarem”, “Ophryterpnomyia latifrons / det. F. Hendel”, “Ophyroterpnomyia latifrons / det. F. Hendel”, 1–10.07.1927, 2 $, 11–20.07.1927, 7 $ (Zerny) (NHMW); Para, Belem, 10.1969, $ (Aitken); Ecuador: Past. Prov., Santa Clara, 30.06.1976, $ (Turner); Tung., Banos (39 km S E), 25.01.1976, $ (Spangler) (USNM); PERU: Vilcanota, “latifrons / det. F. Hendel”, 3 $ (HMNH); Urubambafl., Umahuankilia, 17.09.1903, $ [Garlepp] (Coll. Lichtwardt) (DEI); ibidem, 17.09.1903, 2 $; ibidem, 12, 15, 16.09.1909, 3 $; Meshagua, 10, 30.09.1903, 2 $ [Garlepp] (Coll. Schnuse) (MTD); Iquitos, 03–04.1931, $ (Shannon); 80 km NE Iquitos on Rio Yanamo (1 km upriver from Rio Amazon, 15–26.07.1995, # (Levis) (USNM); Bolivia: Songo, “latifrons / det. F. Hendel”, $ (HMNH); Mapiri, S. Carlos, 800 m, 11.01.1903, $ [Garlepp] (Coll. Schnuse) (MTD); Paraguay: Depto Alto Parana, 14–16.04.1986, $ (Pogue, Solis) (USNM).
Comments. The original description of the female (Hendel, 1909a) is quite complete and needs no addition; the male was described by Frey (as Stylophthalmyia fascipennis Frey, 1926) and Blanchard (as Willineria orfilai Blanchard, 1951), including excellent figures. The male postabdomen was briefly described and figured by Steyskal (1963). 
P. latifrons differs from other species of the genus by the following characters: wing of normal outline, without lobes posteriorly in both sexes; vein R-M at level of R1 apex and crossband through vein R-M in both sexes at most barely touching oblique subbasal band; eye span of male (8.0–15.3 mm) greater than in other species; parafacialium of female between antenna and eye distinctly blackened. 
Prior to this study, P. latifrons was known only from Bolivia, Peru, Guatemala, Salvador, Honduras, Nicaragua, Costa Rica, Panama (Steyskal, 1963, 1968) and northern Brazil (Hendel, 1936). Now, it is recorded for the first time from Mexico, Trinidad, Venezuela, Ecuador and Paraguay.
Plagiocephalus intermedius Kameneva, sp. n. (figs. 1, 3; 2, 3; 2, 5)
Material. Type. Holotype #: Costa Rica: Puntarenas: Monteverde, San Luis, Buen Amigo, 1000-1350 m, 09.1994, #3224 (Fuentes); Paratypes 3 #, 17 $: Costa Rica: Cartago: A. C. Amistad, P. N. Tapanti, 1150 m, 01.1994, # (Mora); Guanacaste: Rio San Lorenzo, Tierras Morenas, Z. P. Tenorio, 1050 m, 01.1993, $ (Rodriguez); P. N. Guanacaste: Est. Cacao, 07.1989, $ (GNP Biod. Sur.); ibidem, SW side Volcan Cacao, 1000-1400 m, 11–12.1989, $ (Blanco, Chaves); ibidem, Lado SO Volcan Cacao, 800-1600 m, 12–17.07.1993, $ (Fuentes); Puntarenas: Monteverde, San Luis, Buen Amigo, 1000-1350 m, 09.1994, $; ibidem, 11.1994, #; ibidem, 25.11–10.12.1996, # (Fuentes); Est. Pittier, Sendero Pittier, 1670 m, 26.06.1995, $ (Angulo); ibidem, 21.06–4.07.1995, 2 $ (Moraga); ibidem, 25.06-4.07.1995, 3 $ (Zumbfado); ibidem, 1700 m, 3.07.1995, 2 $ (Zumbado); Buenos Aires, Est. Altamira, Sendero Los Gigantes, 1450 m, 4.01-3.02.2000, 4 $ (Rubi) (INBio).
 Description. Male (fig. 1, 3). Head strongly transverse with eyes moderately stalked (distance across eyes 3.0-7.0 mm), reddish-yellow, with dorsolateral portions of occiput, posterior portion of frons and ocellar triangle brown to black. Frons 0.13–0.2 as long as wide and 6.3–10.8 as wide as eye, with many black setulae. Head length: height: width ratio = 1.5: 2.0: 10. Vertical, postocellar, ocellar and orbital setae not shorter than in females, at most as long as flagellomere 1 wide; frontal setae not expressed. All setae and setulae of the head are black. Scapus and pedicel uniformly yellow, without darker marks, flagellomere 1 light yellow, 1.8 times longer than wide. Arista brown, 3.5–4.1 times longer than flagellomere 1, with very short lightly pubescence. Face white microtrichose without dark spots. Palpus not extending beyond anterior oral margin, pale yellow, with black setulae at apex. Proboscis capitate, reddish-yellow with brown and black setulae.
Thorax brownish black, sparsely yellowish-grey microtrichose, with antepronotum, postpronotal lobes, scutellum, subscutellum and mediotergite mostly subshining brown. Mesonotum with brown microtrichose pattern, without dots at bases of setulae. One supraalar seta, two dorsocentrals, prsc setae present. Scutellum dull sparsely grey microtrichose medially, with median white stripe apically and on under side, darker on sides, with 4 long setae. Anepisternum and katepisternum uniformly yellowish-grey microtrichose, without dark spots at bases of setulae. All setae and setulae of the thorax brown to black. 
Wing of ordinary outline; costal vein between vein Sc and vein R1 apices unmodified, almost straight. Basicostal cell brown only in apical 1/3, costal cell brown in basal 1/5 and in apical 3/5, with little hyaline spot before its brown end. Pterostigma 5–7 times as long as wide, hyaline to yellow on basal half and brownish on apical. R1 vein setulose only on apical half (11-13 black setulae). R2+3 vein almost straight, slightly sinuate, and as R4+5 vein bare. Wing pattern hyaline with 3 brownish-grey crossbands. Basal crossband restricted to grey spot from basicostal cell to basad of br cell and apicad of bcu cell, with dm cell and basal bcu cell widely hyaline. Brown subbasal crossband from apicad of costal cell widely and obliquely crossing wing in RS bifurcation almost to posterior margin of wing and crossing dm-cu vein to connected with big brown spot on the apex of wing. Pterostigmal crossband reduced to little brown spot above vein R4+5 (in one specimen clearly connected with R-M vein). R-M vein far before end of R1 vein. Postero-apical lobe of bcu cell very short, not exceeding BM-Cu vein level. Upper calypter slightly longer than lower calypter, white, with white fringe. Halter white.
Legs unmodified, moderately setulose (setae and setulae black); fore (including coxae) and mid legs yellow; hind tibia yellow to brown, hind femora brown and hind tarsi yellow.
Abdomen dark brown and uniformly black setulose; tergite 1–2 sparsely grey microtrichose, tergites 3 and 4 with narrow grey microtrichose areas at anterior and posterior margins; tergite 5 without grey microtrichose, shorter than tergite 4. Male genitalia not examined.
Female similar to male, except head unmodified, slightly widened (fig. 2, 5). Head length: height: width ratio = 1.0: 1.2: 2.0. Face white microtrichose, with black microtrichose spot between bases of antennae and 2 horizontal elongate shining brown spots medially of antennal grooves. Parafacial between antenna and eye completely yellow. Gena white microtrichose, with C-shaped brown microtrichose marks. Frontal vitta black setulose and white microtrichose, with 2 brown spots above antenna. Scapus and pedicel uniformly reddish yellow, flagellomere 1 reddish yellow, slightly darkened on apical half. Wing (fig. 2, 3): pterostigmal crossband wedge-like always covering R-M vein, but not or barely touching oblique subbasal fascia. Abdominal tergite 5 with narrow grey microtrichose areas at anterior and posterior margins; slightly shorter than tergite 4. Tergite 6 small, exposed, without grey microtrichose, with 4–5 short marginal setulae. Tergo-sternite 7 brown, black setulose, slightly longer than tergites 3–6 together. Oviscape black, not shorter than four preceding tergites together. Aculeus long and narrow; cercal unit elongate oval. Spermathecae not examined.
 Measurements (length in mm). Male. Body 4.5–5.8, wing 4.7–6.1. Female. Body (with oviscape) 7.5–9.6, wing 5.0–6.5, oviscape dorsally 2.2–2.5, aculeus 2.2–2.8.
Comments. The new species is known only from Costa Rica. It differs from other species of the genus by combination of the following characters: the eye span in male less than in P. latifrons, like in P. lobularis; wing venation like in P. lobularis: the vein R-M proximally of the vein R1 apex, but the pattern of wing similar to P. latifrons: the crossband through vein R-M in both sexes at most barely touching oblique subbasal band; the wing of male of normal outline, without posterior lobes, like in P. latifrons; the parafacialium of female between antenna and eye completely yellow, like in P. lobularis.

I wish to express my sincere thanks to Valery A. Korneyev for reading this manuscript and useful critical comments and his assistance in preparation of computer artwork. Specimens studied were borrowed or examined through the kindness of the following collection curators: Dr. Joachim Ziegler (DEI, currently ZMHB), Dr. Lászlo Papp (HMNH), Dr. Manuel Zumbado (INBio), Dr. Karla Schneider (MLUH), Dr. Uwe Kallweit (MTD), Dr. Brian B. Brown (NHMLA), Dr. Ruth-Eva Contreras-Lichtenberg and Mr. Peter Sehnal (NHMW), Dr. Steve Marshall (UG), Dr. David G. Furth and Dr. Allen L. Norrbom (SEL USDA, material deposited in the USNM), Dr. Wolfram Mey and Dr. Hella Wendt (ZMHB), Dr. Lars Vilhelmsen (ZMUC). Dr. F. Christian Thompson and Dr. Irina Brake (USDA SEL) kindly provided me with some important literature. I thank Dr. Andrew Whittington (National Museums of Scotland, Edinburgh) for reading this paper on its final stage and valuable corrections.
This paper is a part of study supported by the travel grants from the Curtis Sabrosky Fund (USNM & SEL BARC USDA, Washington, D.C.) and the Ernest Mayr Fund (Museum of Comparative Zoology, Cambridge, Pa., U.S.A.), a grant from INBio (Santo Domingo, Costa Rica) in 2001 and a stipend from the Deutscher Academischer Austauschdienst (DAAD, Bonn, Germany) in 2002 (Ref. 322, Kennziffer A/02/16257).

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Fig. 1. Plagiocephalus, male, total view, dorsally.
1 — P. latifrons (Hendel); 2 — P. lobularis Wiedemann; 3 — P. intermedius Kameneva, sp. n.
Рис. 1. Plagiocephalus, самец, общий вид, дорсально.
1 — P. latifrons (Hendel); 2 — P. lobularis Wiedemann; 3 — P. intermedius Kameneva, sp. n.
Fig. 2. Plagiocephalus, female.
1–3 — wing: 1 — P. latifrons (Hendel); 2 — P. lobularis Wiedemann; 3 — P. intermedius Kameneva, sp. n.; 4–5 — head: 4 — P. latifrons (Hendel); 5 — P. intermedius Kameneva, sp. n.
Рис. 2. Plagiocephalus, самка.
1–3 — крыло: 1 — P. latifrons (Hendel); 2 — P. lobularis Wiedemann; 3 — P. intermedius Kameneva, sp. n.; 4–5 — голова: 4 — P. latifrons (Hendel); 5 — P. intermedius Kameneva, sp. n.