_18_Grichanov Negrobov/Image_001.png)
Кавказский энтомол. бюллетень 14(1): 95–104 © CAUCASIAN ENTOMOLOGICAL BULL. 2018
1All-Russian Institute of Plant Protection, Podbelskiy roadway, 3, St. Petersburg, Pushkin 196608 Russia. E-mail: grichanov@mail.ru
2Voronezh State University, Universitetskaya sq., 1, Voronezh 394006 Russia. E-mail: negrobov@list.ru
1Всероссийский институт защиты растений, шоссе Подбельского, 3, Санкт-Петербург, Пушкин 196608 Россия
2Воронежский государственный университет, Университетская пл., 1, Воронеж 394006 Россия
Key words: Diptera, Dolichopodidae, Paleomedeterus, Baltic amber, new synonym, key.
Ключевые слова: Diptera, Dolichopodidae, Paleomedeterus, балтийский янтарь, новый синоним, определительная таблица.
Abstract. The Baltic amber genus Palaeomedeterus Meunier, 1894 (Diptera: Dolichopodidae) is redescribed and assigned to the subfamily Peloropeodinae. The genus Gheynia Meunier, 1899, syn. n. is placed in synonymy with Palaeomedeterus. Palaeochrysotus ignavus Meunier, 1907 is designated as the type species of Palaeomedeterus. The previous designation of “Tipula culiciforme Meunier, 1899” (nomen nudum) as the type species of Palaeomedeterus is considered invalid. In addition, the names Dolichopus soccata Meunier, 1899 and Diaphorus fernandi Meuffels et Grootaert, 1999 are also considered nomina nuda. Palaeomedeterus bifurcatus (Meunier, 1907), comb. n. (from Gheynia), P. ignavus (Meunier, 1907) and P. lassatus (Meunier, 1907) are redescribed. The genus Palaeomedeterus is similar to the extant genera of the subfamily Peloropeodinae, but it does not demonstrate any apomorphic character established for the extant genera. A key for males of seven species of Palaeomedeterus known from Baltic amber (Eocene / Oligocene) is given.
Резюме. Известный из балтийского янтаря (эоцен / олигоцен) род Palaeomedeterus Meunier, 1894 (Diptera: Dolichopodidae) переописан и помещен в современное подсемейство Peloropeodinae. Ископаемый род Gheynia Meunier, 1899, syn. n. из того же янтаря сведен в синонимы к Palaeomedeterus. Palaeochrysotus ignavus Meunier, 1907 обозначен типовым видом рода Palaeomedeterus. Прежнее обозначение «Tipula culiciforme Meunier, 1899» (nomen nudum) в качестве типового вида Palaeomedeterus признано недействительным. Названия Dolichopus soccata Meunier, 1899 и Diaphorus fernandi Meuffels et Grootaert, 1999 признаны nomina nuda. Переописаны Palaeomedeterus bifurcatus (Meunier, 1907), comb. n. (из Gheynia), P. ignavus (Meunier, 1907) и P. lassatus (Meunier, 1907). Род Palaeomedeterus наиболее близок к современным родам Peloropeodinae, но не обнаруживает апоморфных признаков, установленных для современных родов. Составлен определитель по самцам семи видов Palaeomedeterus, известных из балтийского янтаря.
DOI: 10.23885/1814-3326-2018-14-1-95-104
The subfamily Peloropeodinae was created by Robinson [1970] with the type genus Peloropeodes Wheeler, 1890. Now 17 extant genera are considered in this subfamily [Grichanov, 2017a]. It can be distinguished from other subfamilies by the following combination of characters: wing discal cell fused with 2nd basal cell; vertex not excavated; wing vein M2 absent; antennal scape without setae on dorsal surface; posterior mesonotum distinctly flattened and slightly depressed, from 1/3 to 1/2 of surface between dorsocentral setae, and distinct from curved anterior mesonotum; mid and/or hind femur with distinct anterior or anterodorsal preapical seta. Selivanova and Negrobov [1997] suggested the placement of two extinct genera in this subfamily, monotypic Gheynia Meunier, 1899 and Palaeomedeterus Meunier, 1894 with seven described species. Grichanov [2000] recorded Palaeomedeterus for the Ukrainian amber (from the Rovno Region).
Several pieces with inclusions of Gheynia bifurcata
Meunier, 1907, and also with two Palaeomedeterus species of Baltic amber are recently studied. This paper aims to redescribe the known taxa with taxonomical notes and to give a key to species of Palaeomedeterus from Baltic amber including P. bifurcatus (Meunier, 1907), comb. n.
The specimens studied are housed at the collection of the Paleontological Institute of the Russian Academy of Sciences (PIN, Moscow, Russia). They were studied and illustrated with ZEISS Discovery V-12 stereomicroscope and AxioCam MRc5 camera. Morphological terminology follows Grichanov and Brooks [2017]. The relative lengths of the antennomeres and podomeres should be regarded as representative ratios and not measurements. Body length is measured from the base of the antenna to the tip of abdominal segment 6. Antenna length is measured from the frons to the stylus apex. Wing length is measured from the base to the wing apex.
Palaeomedeterus Meunier, 1895: 175; 1907: 199 (as synonym of Palaeochrysotus Meunier, gen. nov.).
Gheynia Meunier, 1899b: 322, syn. n. Type species: Gheynia bifurcata Meunier, 1907, by subsequent monotypy in Meunier [1907: 199] (as “Gheynius bifurcatus”).
Palaeochrysotus Meunier, 1907: 199; Evenhuis, 1994:
366 (as synonym of Palaeomedeterus Meunier, 1895). Type species: Palaeochrysotus horridus Meunier, 1907, by subsequent designation of Spahr [1985: 36].
Type species: Palaeochrysotus ignavus Meunier, 1907: 210, here designated.
on males of the type species Palaeochrysotus ignavus, males and females of Palaeomedeterus bifurcatus comb. n. and a male of
P. lassatus (Meunier, 1907) studied by the authors of this paper. Length 1.5–3 mm; body dark, metallic, with dark setae;
dorsal part of postcranium slightly concave; pair of strong and long ocellar bristles; face without setae, relatively broad, slightly narrowed downward, at clypeus about as wide as postpedicel height; clypeus small, slightly convex; facial suture distinct at eye margins; antenna with scape and pedicel small; scape glabrous, with angular inner apex; pedicel globular, with circlet of apical setulae of approximately equal length, with one apicodorsal seta strong; postpedicel much larger than pedicel; arista-like stylus dorsal to dorsoapical, filiform, pubescent, with its 1st segment short; proboscis short, setose; palpus moderately large, haired, with one strong seta; posterior third of mesonotum distinctly flattened; acrostichals distinct; six dorsocentrals; two notopleurals; scutellum with two strong bristles and two lateral hairs; fore and mid coxae with anterior and apical setae; hind coxa with one bristle at middle; legs simple, with simple setae and bristles; mid and hind femora with strong anterior subapical bristle; tibiae with strong apical setae; mid and hind tibiae with strong anterodorsal and posterodorsal bristles, with some short ventral setae; hind tibia with row of short dorsal setae in apical half, with strong dorsal subapical bristle; hind tarsus simple, with some short ventral setae; wing distinctly shorter than body, relatively broad; costa reaching M1; R1 ending far before level of dm-m; R2+3 and R4+5 gradually diverging to wing apex, R2+3, R4+5 and M1 almost straight; R4+5 and M1 subparallel behind dm-m; M1 joining costa right behind wing apex; distal section of M4 2–3 times longer than dm-m; alula not developed; lower calypter distinct, with setae; halter with well- developed rounded knob, which shorter than halter stem; male abdomen with well-developed setose terga 1–5 and sterna 2–4; tergum 6 small, bare, mostly concealed; segment 7 small, with tergum and sternum; segment 8 large, covered with setae; female similar to male; processes of postpedicel short.
Remarks. The genus Palaeomedeterus was proposed by Meunier [1895] with none included species and without description of characters of generic significance. This author supposed close relationship of fossil species of the genera Palaeomedeterus, Chrysotus Meigen, 1824 (Diaphorinae), Medetera Fischer von Waldheim, 1819 (Medeterinae), and Oppenheimiella Meunier, 1893 (now in Opetiidae), and he pointed out a great variability of shape of the antennal postpedicel and position of the arista-like stylus on this segment in the Palaeomedeterus. Validating the name, Meunier provided his proposal with line drawings of antenna for six different unnamed Palaeomedeterus species (thus the name Palaeomedeterus is available according to the article 12.2.7 of International Code of Zoological Nomenclature [1999]). The authors of
this paper suppose that the Meunier’s schematic drawings could be associated with different dolichopodid genera with extinct species known to Meunier [1907, 1908a, b].
Meunier mentioned the name Palaeomedeterus in several of his papers and short notes published between 1895 and 1907, giving no additional characters to the generic concept. One of these papers [Meunier, 1899a] was recently used for establishing new nomenclatural acts [Evenhuis, 1994; Meuffels, Grootaert, 1999]. Thus, Evenhuis [1994] designated the type species for Palaeomedeterus, “Tipula culiciforme” Meunier, 1899, “by subsequent monotypy”, and Meuffels and Grootaert [1999] proposed a new replacement name Palaeomedeterus meunieri for “Tipula culiciformis Meunier, 1899” (nec Linnaeus, 1767). However, despite its title (“Revision of fossil dipteran types of Loew deposited in the Königsberg Provincial Museum”), the work of Meunier [1899a] contains a list of the Loew’s museum identification labels reprinted with a number of errors and misprintings, with each label accompanied usually with Meunier’s notes on taxonomical position of the particular inclusion. For example, the name “Tipula culiciforme, Löw”, was repeated twice (p. 174), each time for different taxa (according to Meunier). Reading carefully original monograph of Loew [1850], we cannot find the species name “Tipula culiciforme”. At the same time, we can find there an outdated classification of nematoceran Diptera, including “die Familie der Tipularia culiciformia” (p. 29), “Tipularia fungicola” (p. 32), “Tipularia terricola” (p. 35), etc. The authors suppose that Meunier [1899a] erroneously reprinted these names from Loew’s labels as “Tipulaculiciforme”, “Tipulidae fongicola”, “Tipulaterricola” (p. 174), having no intention to name the flies. Also, Meunier usually did not provide his notes under the listed species and other taxa with diagnostic characters, making them nomina nuda (if they were not published before).
Regarding “Tipula culiciforme” (No 14515), Meunier’s note contains two common characters (large postpedicel and bristled hind basitarsus) of the genus Dolichopus, a member of the subfamily Dolichopodinae, distinguishing the latter genus from Palaeomedeterus, and general remark on a great variability of the antenna within Palaeomedeterus. The authors hope that nobody considers this note as a species description of “Tipula culiciforme”. It is worth noting here that “Tipula terricola, Löw” was also mentioned by Meunier as a member of Palaeomedeterus (p. 174) without both description and diagnostic character. Therefore, both “Tipula culiciforme, Löw” and “Tipula terricola, Löw” (sensu Meunier) must be considered at most nomina nuda, and the designation of Tipula culiciforme as the type species for Palaeomedeterus “by subsequent monotypy” [Evenhuis, 1994] must be considered invalid.
The same publication [Meunier, 1899a] contained also the list of the Loew’s materials labeled as members of the family Dolichopodidae (p. 179). One specimen labeled as “Dolichopodidae L[oew]” was referred to the genus Chrysotus (Diaphorinae). Two specimens labeled as “2. Psilopus” (now the name Psilopus Meigen, 1824 is a synonym of Sciapus Zeller, 1842, Sciapodinae) had the following remark: “Dans des travaux antérieurs, j’ai fait connaître les genres suivants: Palaeoargyra, Palaeomedeterus, Medeterus et Argyra” [Meunier, 1899a: 179], i.e. Meunier
was uncertain in association of the material with one of the four genera belonging now to Diaphorinae, Medeterinae and Peloropeodinae. One inclusion labeled as “Dolichopus soccatus, Löw” had no Meunier’s remark despite the obvious impossibility of finding the extant Canadian Dolichopus soccatus Walker, 1849 (currently an unrecognized species) in the Baltic amber. Finally, one specimen labeled as “Diaphorus. ♂. Löw” and printed by Meunier as “1. Dolichopus soccata ? Diaphorus. ♂. Löw” had the following remark [Meunier, 1899a: 179]: “Ce Dolichopodidae dont le troisième article des antennes est conique et assez allongé, est referable au genre cité. Je ne puis admettre, avec Löw, que c’est un Diaphorus, car le troisième article des diptères de ce genre est ‘scheibenrand’. ”. It means that Meunier did not accept Loew’s identification of this specimen as Diaphorus sp., placing this fly in the genus Dolichopus (sensu Loew) on the base of the non-rounded postpedicel shape of the specimen. The name “Dolichopus soccata” [Meunier, 1899a] had no any diagnostic character and should be considered nomen nudum, but it was listed by Evenhuis [1994] within the genus Diaphorus Meigen, 1824 and was renamed as Diaphorus fernandi by Meuffels and Grootaert [1999]. We here consider the latter name as an unjustified new name for an invalid name.
Meunier [1899b] proposed also a new genus Gheynia
with none included species, without description, but with a reference to a picture of antenna of unnamed fossil species [Meunier, 1894]. He noted close relationship of Gheynia and Palaeomedeterus differing from each other in the shape of the postpedicel. Meunier [1907, 1908b] published a short description of Gheynia bifurcata Meunier, 1907 (as “Gheynius bifurcatus”), adding three more line drawings of the postpedicel. A male postpedicel pictured [Meunier, 1908b: Fig. 81] is almost identical to that published in Meunier [1894]. Figs 83 and 84 [Meunier, 1908b] demonstrate individual variability of female postpedicel in this species. It is interesting that the Fig. 84 [Meunier, 1908b] is quite similar to the Fig. II [Meunier 1895] illustrating one of the Palaeomedeterus species. Ulrich and Schmelz [2001] published a photo of the female Gheynia bifurcata (along with a possible prey, enchytraeid worm), which added some important diagnostic characters to the original description of the species.
Palaeomedeterus bifurcatus (Meunier, 1907), comb. n.
Gheynia bifurcata Meunier, 1907: 199; 1908b: 58 (as Gheynius
bifurcatus); Ulrich, Schmelz, 2001: 89; Evenhuis, 1994: 366.
Palaeomedeterus fessus (Meunier, 1907)
Palaeochrysotus fessus Meunier, 1907: 210; 1908b: 55.
Palaeomedeterus fessus (Meunier, 1907): Evenhuis, 1994: 366.
Palaeomedeterus hirsutus (Meunier, 1907)
Palaeochrysotus hirsutus Meunier, 1907: 210; 1908b: 49.
Palaeomedeterus hirsutus (Meunier, 1907): Evenhuis, 1994:
366.
Palaeomedeterus horridus (Meunier, 1907)
Palaeochrysotus horridus Meunier, 1907: 210; 1908b: 47.
Palaeomedeterus horridus (Meunier, 1907): Evenhuis, 1994:
366.
Palaeomedeterus ignavus (Meunier, 1907)
Palaeochrysotus ignavus Meunier, 1907: 210; 1908b: 50.
Palaeomedeterus ignavus (Meunier, 1907): Evenhuis 1994:
366.
Palaeomedeterus languidus (Meunier, 1907)
Palaeochrysotus languidus Meunier, 1907: 210; 1908b: 54.
Palaeomedeterus languidus (Meunier, 1907): Evenhuis 1994:
366.
Palaeomedeterus lassatus (Meunier, 1907)
Palaeochrysotus lassatus Meunier, 1907: 210; 1908b: 55.
Palaeomedeterus lassatus (Meunier, 1907): Evenhuis 1994:
366.
Palaeomedeterus lentus (Meunier, 1907)
Palaeochrysotus lentus Meunier, 1907: 210; 1908b: 52.
Palaeomedeterus lentus (Meunier, 1907): Evenhuis 1994: 366. Remarks. This species was described with the dorsal arista-like stylus, but was pictured with the apical stylus [Meunier, 1908b: Fig. 70]. We consider the stylus position to be dorsal because Meunier [1908b: 9] used the latter character in his generic key for all species of
Palaeochrysotus.
Palaeomedeterus culiciformis (Meunier, 1899).
Tipula culiciformis Meunier, 1899a: 174 (as “Tipula culiciforme, Löw”, nec Linnaeus, 1767), nomen nudum.
Palaeomedeterus culiciformis Evenhuis, 1994: 366 (as “Palaeomedeterus culiciformis Meunier, 1899”). Unavailable name; replacement proposed for an unavailable species- group name.
Palaeomedeterus meunieri Meuffels et Grootaert, 1999: 291 (nom. nov. for “Tipula culiciformis Meunier, 1899”, nec Linnaeus, 1767). Unavailable name; a new name proposed for an unavailable species-group name.
Palaeomedeterus bifurcatus (Meunier, 1907) (Figs 1–8)
Material. Seven completely preserved males and two females have been selected for the redescription from amber pieces labelled: “Baltic Amber, Upper Eocene – Lower Oligocene Gheynia bifurcata Meunier, det.
Negrobov & O. Selivanova 1996 Palaeomedeterus bifurcatus (Meunier), det. I. Grichanov 2017, with the numbers 93, 97, 209, 343, 467, 492, 514 (males), 151, 236 (females)” (PIN).
Head: vertex not excavated; vertical bristle strong and long, located at upper corner of frons; short postvertical seta as a linear
continuation of postocular setal row; one pair of strong ocellar bristles (adjacent hairs invisible); single row of short dark simple postoculars of about equal length; eyes with microscopic hairs between facets; upper and lower facets about equal in size; face shining, under antenna nearly twice as wide as postpedicel height, narrowing towards clypeus; clypeus small and narrow, nearly as high as wide; antenna about as long as eye height, dark; scape and pedicel small, simple; scape vaselike, glabrous, with angular inner apex; pedicel globular, with circlet of apical setulae of approximately equal length, with one dorsal seta strong; postpedicel swollen at base, flattened laterally, with two drawn-out apices, longer than high at base (12 : 10), long haired; ventral process of postpedicel usually longer than dorsal process; arista-like stylus inserted in apical incision, filiform, pubescent, with its 1st segment being very short. Length ratio of scape to pedicel to postpedicel to arista-like stylus, 6 : 6 : 12 : 48. Palpus and proboscis dark, small, sparsely haired; palpus as long as clypeus, ovate, with strong apical bristle. Thorax: with posterior third of mesonotum distinctly flattened; two regular rows of 6 strong dorsocentrals decreasing in length anteriorly; acrostichals biserial, distinct, reaching posterior depression of mesonotum; few hairs on anterior slope of mesonotum; 1 pair of strong scutellars, as long as posterior dorsocentrals, and two lateral hairs, adjacent to median bristles; postnotum small; 1 strong proepisternal bristle just above fore
coxa; proepimeron without strong setae.
Legs including coxae dark, simple, evenly covered with ordinary setulae, with strong bristles; fore coxa with short simple hairs and several subapical setae anteriorly; mid and hind coxae with 1 strong lateral bristle at middle; claws and pulvilli on all legs small; mid trochanter with 1 dorsal seta; mid and hind femora with strong anterior preapical bristle, as long or slightly longer than femur height; fore tibia with at most 1 weak dorsal, with 2–3 short apical setae; mid tibia with 2 pairs of antero- and posterodorsals including strong and long upper anterodorsal bristle, with or without additional short anterodorsal at base, with 4 strong apicals; hind tibia with 1–2 pairs of short antero- and posterodorsal setae in basal half, dorsal row of short dorsal setae in distal half, with strong dorsal subapical bristle, with 2–3 short ventral setae, with 3–4 apical setae; tarsomeres of all legs with very short apical setae; fore leg length ratio (from femur to tarsomere 5): 51 : 51 : 24 : 13 : 10 : 8 : 8, mid leg: 59 : 65 : 25 : 15 : 11 : 7 : 7, hind leg: 64 : 78 : 15 :
20 : 11 : 9 : 7.
Wing: hyaline, with dark veins; R1 ending far before level of dm-m; R2+3 and R4+5 gradually diverging to wing apex, R2+3, R4+5 and M1 almost straight; R4+5 and M1 subparallel behind dm-m; M1 joining costa right behind wing apex; ratio of part of costa between R2+3 and R4+5 to this between R4+5 and M1 to dm-m to distal part of M4, 25 : 18 : 15 : 36; crossvein dm-m nearly straight, forming right angles with M1 and with M4 longitudinal veins, as long as maximum distance between R4+5 and M1 veins; anal wing distinct, almost reaching wing margin; anal lobe developed; anal angle obtuse; lower calypter light, with long dark setae; halter light, with well-developed rounded knob, shorter than halter stem.
Abdomen: conoid, covered with hairs, with short marginal
tergal setae and sparse sternal hairs on segments 2–5; sterna 2–4 well sclerotised; tergum 6 small and bare; segment 7 small, with distinct tergum and sternum; segment 8 large, positioned left basodorsally, covered with setae; epandrium globular; hypandrium raised from middle of epandrium, projected, bilobate, with lobes gradually broadened apically, rounded at apex; phallus thick, with small ventral hook at apex; distoventral epandrial lobe broad, slightly projected, fused with epandrium, with one long and 1–2 short ventral setae; surstylus bilobate, with short subequal in length lobes, bearing short setae at apex, with ventral lobe narrower, than dorsal lobe of surstylus; postgonite projected, bilobate, with hooked pointed lobes, cercus small, rounded, covered with short cilia.
Length (mm): body without antennae 2–2.25, antenna 0.6, wing 1.9 : 0.7.
Female. Similar to male; postpedicel (including short ventral process) as long as high (9 : 9), dorsal process of postpedicel weakly pronounced; hemitergite each with at least 3 short thick setae; body length 2–2.25 mm, wing length 2 mm.
bifurcatus. Recently, Ulrich and Schmelz [2001] found a female of this species with a possible prey, enchytraeid worm, in a single piece of Baltic amber.
Palaeomedeterus lassatus (Meunier, 1907) (Figs 9–15)
Material. One completely preserved male partly covered with milky-white decay coating in a piece of amber labelled: “Baltic Amber, Upper Eocene – Lower Oligocene Palaeomedeterus lassatus (Meunier), det. I. Grichanov 2017” (PIN).
virtually indistinguishable. Major bristles dark.
Head: vertex not excavated; vertical bristle strong and long, positioned at upper corner of frons; short postvertical seta as linear continuation of postocular setal row; one pair of strong ocellar bristles (adjacent hairs invisible); single row of short dark simple postoculars of about equal length; eyes with microscopic hairs between facets; upper and lower facets about equal in size; face (poorly visible) moderately broad; eyes distinctly separated; antenna about as long as eye height, dark; scape and pedicel small, simple; scape vaselike, glabrous, with angular inner apex; pedicel globular, with circlet of apical setulae of approximately equal length, with 1 dorsal seta strong; postpedicel flattened laterally, with small pointed ventral projection at apex, higher than long (9 : 5), haired; arista-like stylus inserted in subapical emargination, filiform, pubescent, with its 1st segment being very short; length ratio of scape to pedicel to postpedicel to arista-like stylus, 4 : 4 : 5 : 43; palpus and proboscis small, sparsely haired; palpus with strong apical bristle.
Thorax: with posterior third of mesonotum distinctly flattened; two regular rows of 6 strong dorsocentrals decreasing in length anteriorly; acrostichals biserial, distinct, reaching posterior depression of mesonotum; few hairs on anterior slope of mesonotum; one pair of strong scutellars, as long as posterior dorsocentrals, and two lateral hairs, adjacent to median bristles; postnotum small; one strong proepisternal bristle just above fore coxa; proepimeron without strong setae.
Legs including coxae simple, evenly covered with ordinary setulae, with strong bristles; fore coxa with short simple hairs and several subapical setae anteriorly; mid and hind coxae with one strong lateral bristle at middle; claws and pulvilli on all legs small; mid trochanter with one dorsal seta; mid and hind femora with strong anterior preapical bristle, as long as or slightly longer than femur height; fore tibia with at most one weak dorsal, with 2–3 short apical setae; mid tibia with two pairs of antero- and posterodorsals including subequal in length anterodorsal bristles, with or without additional short anterodorsal at base, with four strong apicals; hind tibia with 1–2 pairs of short antero- and posterodorsal setae in basal half, dorsal row of short dorsal setae in distal two-thirds, with dorsal subapical bristle which not stronger than apicoventral bristle, with 2–3 short ventral setae, with 3–4 apical setae; tarsomeres of all legs with very short apical setae;
fore leg length ratio (from tibia to tarsomere 5): 42 : 16 : 8 : 6 : 5 : 6,
mid leg: 53 : 21 : 11 : 8 : 6 : 7, hind leg: 60 : 15 : 18 : 11 : 7 : 7.
Wing: hyaline, with dark veins; R1 ending far before level of dm-m; R2+3 and R4+5 gradually diverging to wing apex, R2+3, R4+5 and M1 almost straight; R4+5 and M1 subparallel behind dm-m; M1 joining costa right behind wing apex; ratio of part of costa
between R2+3 and R4+5 to this between R4+5 and M1 to dm-m to distal part of M4, 22 : 13 : 11 : 35; crossvein dm-m nearly straight, forming right angles with M1 and with M4 longitudinal veins, as long as maximum distance between R4+5 and M1 veins; lower calypter light, with long setae; halter light, with well-developed rounded knob, shorter than halter stem.
_18_Grichanov Negrobov/Image_002.jpg)
Figs 1–8. Palaeomedeterus bifurcatus (Meunier, 1907), male.
1 – habitus; 2 – head; 3 – antenna; 4 – thorax; 5 – wing; 6 – fore leg; 7 – mid and hind legs; 8 – abdomen. Рис. 1–8. Palaeomedeterus bifurcatus (Meunier, 1907), самец.
1 – внешний вид; 2 – голова; 3 – усик; 4 – грудь; 5 – крыло; 6 – передняя нога; 7 – средняя и задняя ноги; 8 – брюшко.
_18_Grichanov Negrobov/Image_003.jpg)
Figs 9–15. Palaeomedeterus lassatus (Meunier, 1907), male.
9 – habitus; 10 – antenna; 11 – wing; 12 – fore leg; 13 – mid leg; 14 – hind leg; 15 – hypopygium. Рис. 9–15. Palaeomedeterus lassatus (Meunier, 1907), самец.
9 – внешний вид; 10 – усик; 11 – крыло; 12 – передняя нога; 13 – средняя нога; 14 – задняя нога; 15 – гипопигий.
Abdomen: conoid, covered with hairs, with short marginal tergal setae and sparse sternal hairs on segments 2–5; sterna 2–4 well sclerotised; tergum 6 small and bare; segment 7 small, with distinct tergum and sternum; segment 8 large, positioned left basodorsally, covered with setae; epandrium globular; hypandrium raised from middle of epandrium, projected, bilobate, with lobes gradually broadened apically, rounded at apex; phallus poorly visible, projected, somewhat broadened at apex; distoventral epandrial lobe concealed, not visible; surstylus with only one large lobe visible, elongate-triangular, with narrow curved ventrally apex, with two small ventral preapical tubercles, without distinct setae; postgonite projected, rhomboid, nearly half as long as cercus; cercus long, swollen at base, narrow distally, with flattened and slightly enlarged apex, covered with short cilia, with long dorsal preapical bristle.
Length (mm): body without antennae 1.75, antenna 0.55, wing 1.65 : 0.63.
Female. Similar to male (according with Meunier [1907, 1908b]).
Palaeomedeterus ignavus (Meunier, 1907) (Figs 16–20)
Material. Two completely preserved males partly covered with milky-white decay coating in two pieces of amber labelled: “Baltic Amber, Upper Eocene – Lower Oligocene Palaeomedeterus ignavus (Meunier), det.
Grichanov 2017” (PIN).
Redescription. Male. Similar to Palaeomedeterus lassatus in all respects except as noted.
Head: face moderately broad, under antennae about as wide as postpedicel height, slightly narrowed towards clypeus; postpedicel flattened laterally, with ventral projection at apex, subtriangular, longer than high (10 : 7), haired; arista-like stylus inserted in dorsoapical emargination, filiform, pubescent; length ratio of scape to pedicel to postpedicel to arista-like stylus, 5 : 5 : 7 : 49.
Legs: fore leg length ratio (from tibia to tarsomere 5): 61 : 29 : 17 : 9 : 9 : 8, mid leg: 86 : 42 : 23 : 17 : 10 : 9, hind leg:
96 : 21 : 33 : 19 : 14 : 10.
Wing: ratio of part of costa between R2+3 and R4+5 to this between R4+5 and M1 to dm-m to distal part of M4, 36 : 20 : 18 : 42. Abdomen: epandrium globular; hypandrium raised from middle of epandrium, strongly projected beyond apex of surstylus, bilobate, with narrow band-like lobes, rounded at apex; phallus invisible; distoventral epandrial lobe broad, projected, with pointed distal apex bearing pedunculate seta, with one long ventral seta at base; surstylus located distoventrally, with only one large lobe visible, elongate-triangular, narrow distally, with curved ventrally apex, with one or two small inner preapical tubercles, without distinct setae; postgonite strongly projected, bilobate, with hooked pointed lobes, slightly longer than cercus; cercus long, narrow,
with rounded apex, densely covered with short cilia.
Length (mm): body without antennae 2.5, antenna 0.65, wing 2.3 : 0.9.
Female. Similar to male, being somewhat smaller than male
(according with Meunier [1907, 1908b]).
provided by the author for the male antenna, fore and hind tarsus and hypopygium allow reliable association of the inclusions studied with Palaeomedeterus ignavus.
is not included)
Arista-likestylusapical, insertedindeepslitofpostpedicel; body length 2–2.25 mm; wing length 2 mm ................
.......................................................................... P. bifurcatus
Arista-like stylus dorsal, at most inserted in small notch of postpedicel 2
First two segments of hind tarsus subequal in length; body length 3 mm; wing length 2 mm ............. P. horridus
Hind basitarsus distinctly shorter than next segment 3
Postpedicel reniform, distinctly higher than long; hind basitarsus half as long as next segment; body length 2 mm; wing length 2 mm .................................... P. lentus
Postpedicel about as long as high, with distinct apex; hind basitarsus more than half as long as next segment 4
Hypopygium clavate; cercus with several long cilia at apex; surstylus lanceolate; phallus long and cylindrical; body length 2 mm; wing length 1 mm [Meunier, 1908b]
........................................................................... P. languidus
Another combination of characters; cercus with short hairs at apex 5
Cercus stalk-like, much shorter than surstylus; surstylus narrow, straight almost to apex; body length 3 mm; wing length 2 mm ............................................. P. hirsutus
Cercus about as long as surstylus 6
Cercus swollen at base, narrow distally, with flattened and slightly enlarged apex; postgonite projected, rhomboid, nearly half as long as cercus; body length 1.5–1.75 mm; wing length 1–1.65 mm .......... P. lassatus
Cercus ribbon-like, with rounded apex; postgonite strongly projected, with hooked pointed lobes, slightly longer than cercus; body length 2.5–3 mm; wing length 2–2.3 mm ............................................... P. ignavus
The subfamilies Peloropeodinae with 17 extant genera and Sympycninae with 38 extant genera are very close each to other [Grichanov, 2017a]. As currently defined, peloropeodines are characterized by the posterior mesonotum distinctly flattened and slightly depressed, from 1/3 to 1/2 of surface between dorsocentral setae, and sympycnines differ from the former in the posterior mesonotum not flattened, or at most only slightly flattened immediately anteriad of scutellum [Grichanov, 2011]. Most of those 55 genera are closely related to several large genera, such as Chrysotimus Loew, 1857, Micromorphus Mik, 1878, Nepalomyia Hollis, 1964, and Peloropeodes Wheeler, 1890 (Peloropeodinae), Campsicnemus Haliday in Walker, 1851, Chaetogonopteron De Meijere, 1913, Sympycnus Loew, 1857, Syntormon Loew, 1857, and Teuchophorus Loew, 1857 (Sympycninae), being distinguished by remarkable apomorphies or by male secondary sexual characters (MSSC). However, most species of the listed genera are
_18_Grichanov Negrobov/Image_004.jpg)
Figs 16–20. Palaeomedeterus ignavus (Meunier, 1907), male.
16 – habitus; 17 – head; 18 – wing; 19 – legs; 20 – hypopygium, with inset showing cercus. Рис. 16–20. Palaeomedeterus ignavus (Meunier, 1907), самец.
16 – внешний вид; 17 – голова; 18 – крыло; 19 – ноги; 20 – гипопигий, на врезке показана церка.
also characterized by more or less pronounced MSSC on at least some podomeres.
Palaeomedeterus is assigned to the subfamily Peloropeodinae due to the following synapomorphic character states: eyes distinctly separated; face slightly narrowed downward with small clypeus; posterior third of mesonotum distinctly flattened; antennal pedicel with 1 strong apicodorsal seta; postpedicel much larger than pedicel; mid and hind femora with strong anterior subapical bristle; tibiae with strong bristles; R1 short; distal section of M4 longer than dm-cu; segment 7 small.
Keeping in mind that 2 million years is an optimal
period for rapid species radiation [Goodman et al., 2016; Grichanov, 2017b], and at least some extant dolichopodid genera (as they presently recognized) appeared up to 12 m.y.a. [Goodman et al., 2016], it is little wonder that the Palaeomedeterus species from Baltic amber (30–50 million years old) lack such apomorphies of extant peloropeodine genera as ornamented legs. The arista-like stylus insertion in apical notch of the postpedicel in both sexes is a striking modification of the P. bifurcatus antenna. Somewhat similar modification can be observed in some extant species of several genera from different subfamilies (e.g. Acropsilus Mik, 1878, Chrysotus, Nepalomyia), having no generic significance to our knowledge. Most probably, we deal with an example of recurrent evolution of the character that could independently appear within remote taxa.
Palaeomedeterus species are remarkably similar to the Sympycnites primaevus Grimaldi et Cumming [1999], described by one female from the much older Lebanese amber (125–135 million years old). Up to date, Sympycnites Grimaldi et Cumming, 1999, is not known from Baltic and other younger amber sources. According to current classification, it must be considered in the subfamily Sympycninae. Both Palaeomedeterus and Sympycnites well differ from the fossil Medeterinae and Diaphorinae in the presence of strong anterior preapical bristles on mid and hind femora. Recently, extant Neomedetera Zhu, Yang et Grootaert, 2007 and Udzungwomyia Grichanov, 2018, have been put to Medeterinae despite presence of a distinct anterior preaрiсаl seta on the mid and hind femora [Zhu et al., 2007; Grichanov, 2018]. Nevertheless, these genera well differs from Palaeomedeterus and other genera of the subfamily Peloropeodinae in such characters, as postpedicel about as large as pedicel, semiglobular, with indistinct apex; stylus preapical; legs with rather short major bristles; hind basitarsus much shorter than next segment; postabdomen nearly symmetrical, with epandrial foramen positioned basally.
Palaeomedeterus differs from fossil Dolichopodinae, Sciapodinae and Sympycninae in flattened posterior mesonotum mainly. At present, it is the only recognized genus of Peloropeodinae in Baltic amber. Eight species are here included into this genus, and three of them are redescribed and illustrated in this paper. Meunier [1907, 1908b] provided the line drawing of the hypopygium for one more species of Palaeomedeterus, P. hirsutus. Four more species, P. fessus (only females available), P. horridus (no pictures available), P. languidus and P. lentus were inadequately described and illustrated by Meunier [1907, 1908b]. Their taxonomic link with Palaeomedeterus can
be confirmed, if the type specimens are found and studied (in the Geowissenschaftlicher Zentrum der Georg-August- Universität Göttingen, Germany). Regarding the three species studied in this paper, P. bifurcatus, P. ignavus and
P. lassatus, they have rather similar overall habitus except for the difference in the antennal postpedicel shape. Globular epandrium, reduced sterna 5 and 6, reduced segment 7, and projected bilobate hypandrium with rounded apex are present in males of all species. Nevertheless, the hypopygial surstylus, cercus and postgonite are different in each species (including P. hirsutus).
As a result of this study, the Baltic amber fauna of long- legged flies contains now 8 extinct genera with 37 described species belonging to five subfamilies represented in the recent fauna as well. About 30 species placed by Meunier in the extant genera need to be revised. It is worth noting that Ulrich [2003] also doubted the assignment of most Baltic amber species to the modern genera.
The authors express sincere gratitude to Dr. A.P. Rasnitsyn (Paleontological Institute of the Russian Academy of Sciences, Moscow, Russia) for his kindness in furnishing an opportunity to study the PIN collection.
V. Novikov (St. Petersburg, Pushkin, Russia) kindly presented several amber pieces to the senior author. Two anonymous reviewers kindly commented on earlier drafts of the manuscript.
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Received / Поступила: 3.05.2018 Accepted / Принята: 5.06.2018