The Fossil Strepsiptera (Insecta: Strepsiptera)

831 Systematics

The Fossil Strepsiptera (Insecta: Strepsiptera) RAGNAR KINZELBACH and HANS POHL

Institute of Zoology, Technical University of Darmstadt, Schnittspahnstrasse 3, D-64287 Darmstadt, Germany

Ann. Entomol. Soc. Am. 87(1): 059-070 (1994)

ABSTRACT Three new species of Strepsiptera are described and six additional species are discussed. The oldest fossil records are of four species from several Eocene sites in Europe (Geiseltal, Messel, Baltic amber), one of Mengeidae and three of Myrmecolacidae. At least six species are from Dominican amber of various ages since the Oligocene, comprising four species of Myrmecolacidae, one of Elenchidae, and one of Bohartillidae, which are very close to or even identical with living species. KEY WORDS

THE

Strepsiptera, phylogeny, amber

"STREPSIPTERA PROBLEM" (Kristensen

1981), the problem of the position of stylopids in the natural system, has not been resolved since the description of the taxon by Rossius (1793). There are several possible approaches to a solution: (1) the formulation of more precise questions (e.g., a search for genuine synapomorphies and for truly phylogenetic taxa); (2) an improvement in the knowledge of the ancestry (and piesiomorphic characters) of potential sister-groups;

(3) the investigation and comparison of biochemical characters; and (4) a complete knowledge of all the recent species and as many fossil species as possible. This paper is a contribution to the fourth of these objectives. Good luck and the perceptiveness of some private collectors and colleagues has considerably increased the number of fossil species of Strepsiptera during the last decade. Some new findings are described here. Together with a survey of all the known fossil Strepsiptera, they contribute toward a comparative evaluation

claws; tarsi with dorsal sensory spots; an-

tennae with 4-7 segments . . 3 (Stylopidia) Praementum free, with short palps; anterior branch of MA absent (?); antenna with 7 segments, with flabella on third and fourth segments Mengeidae Hosts unknown, probably grown dwellers; Eocene dry pine forests; Baltic Sea region. 2. Praementum and hypopharynx forming a united sclerite; MA well developed, with anterior branch present; antennae with 6 segments with flabella on third and fourth or third-sixth segments . . . Mengenillidae Hosts Thysanura (Zygentoma), ground dwellers; scleraea of Old World; females with legs, free-living or in pupal cases. 3. Mandibles absent or vestigial; tarsi either 5-segmented with small claws or 4-segmented without claws; tarsi with sensory spots; antenna 5- to 7-segmented with flabellum on third and fourth segments

2.

of these taxa.

^

,_ ~M ,

Corioxenidae

T

.

fj,

„

Hosts Heteroptera, brush dwellers; mainly tropical forests; females turn ventral side

.,.

Key to Male Imagines ot the Families For females, none of which have yet been found as fossils, see Kinzelbach (1971). The Callipharixenidae are known only from females, and for this reason are not included in the following key to males only. The puparia (cf. Stichotrema from Messel) and first instars (cf. Stichotrema eocaenicum [Haupt]) are not sufficiently well known for a reliable key to be given. 1. Tarsi 5-segmented, with strong claws; tarsi without sensory spots; antennae with 6-7 segments, the third and following segments flabellate ; 2 (Mengenillidia) 1. Tarsi either with 2-5 segments, without claws, or with 5 segments, with small

t h t

3.

Mandibles present; tarsi 2- to 4-segmented, without claws 4 4. Tarsi 3-segmented; fourth antennal segment with or without flabellum but equal in size and shape to the more distal segments Halictophagidae Hosts Homoptera, Heteroptera, Blattodea, Saltatoria, Diptera; herbal stratum; worldwide except Antarctica and polar Arctic region. 4. Tarsi 2- or 4-segmented 5 5. Tarsi 2-segmented; antennae 4-segmented with flabellum on third segment Elenchidae

0013-8746/94/0059-0070$02.00/0 © 1994 Entomological Society of America

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5. 6.

Annals of the Entomological Society of America

Hosts Homoptera, herb layer; worldwide. Tarsi 4-segmented; antennae 5- to 7-segmented with flabellum on third, thirdfourth or third, fifth, and sixth segments . 6 Antenna 7-segmented with flabellum on third, fifth, and sixth segments; maxillary base large, at least 5 times as long as max illary palpus Bohartillidae Hosts unknown, (?) Mutillidae; Neotropi cal rain forest.

6. 7.

7.

Antenna 4- to 7-segmented with flabellum on third segment only; maxillary base equal to or smaller than maxillary palpus . 7 Antenna 4- to 7-segmented, with broad, flat segments and flabella Stylopidae Hosts Hymenoptera (Apoidea, Sphecoidea, Vespoidea); worldwide except Antarctica and polar Arctic region. Antenna 7-segmented, with narrow, cylin drical segments and flabella Myrmecolacidae Hosts Hymenoptera (Formicoidea) for males, Saltatoria and Mantodea for fe males; pantropical.

The Fossils, Listed According to Localities Geiseltal near Halle

Stichotrema eocaenicum (Haupt, 1950)

Pseudococcites eocaenicus Haupt, 1950, Geologica 6: 47-48, 108, pi. V/5. Stichotrema eocaenicum: Kinzelbach & Lutz, 1985, Ann. Entomol. Soc. Am. 78: 600-602, figs. 1-3.

Material Examined. One primary larva (Lx), found by Voigt (1938) by chance in the gut con tents of an Eopyrophorus sp. (Coleoptera: Elateridae). Locality and Stratum. Eocene brown coal of the Geiseltal near Halle an der Saale. Characteristics. No characters different from

recent representatives of the relevant taxa. With a length of 0.12 mm (without setae), the larva is

probably a male, which corresponds with L1 measurements of recent Myrmecolacidae: these are sexually dimorphic, with females 1.5-2 times the size of males.

Systematic Position. The distribution of the

bristles, the relatively broad shape, and the me dian clypeolabral groove enable the species to be placed in the Myrmecolacidae and, probably, in the genus Stichotrema. Messel Oil Slate near Darmstadt

Stichotrema sp. (Fig. 1)

Lychnocolax sp. Lutz, 1990, Cour. Forschungsinst. Senckenb. 124: 29-30.

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Material Examined. Host with two male puparia of Strepsiptera, Senckenberg Collection SMF-Mel 196. Unfortunately, the specimens are in a poor state of preservation. Locality and Stratum. Grube Messel (Darmstadt-Dieburg district), Middle Eocene oil slate. Characteristics. Under the tergites of gastric segments 2 and 3 of the host, there are two puparia, probably already empty (the males hatched earlier). Measurements: width 0.97 mm, length 1.093-1.336 mm (Fig. 1 A, B). Host. Formicinae Camponotus is the only re cent genus known to host Strepsiptera (Myrmecolax nietneri Westwood, 1861, from Sri Lanka [Ceylon] [Westwood 1861]). Systematic Position. Tentatively assigned to Stichotrema; known from the Old World and confirmed by other Eocene findings. Baltic Amber

Mengea tertiaria (Menge, 1866)

Triaena tertiaria Menge, 1866, Schriftenr. Naturforsch. Ges. Danzig 2(1): 2-5, figs. 1-6. Mengea tertiaria: Grote, 1886, Can. Entomol. 18: 100; Ulrich, 1927, Z. Morphol. Oekol. Tiere 8(y2): 45-62. Material (only male imagines known).

(1) Danziger Naturkundemuseum (Menge 1866). Specimen lost. (2) Danziger Museum fur Naturkunde and Vorgeschichte, Halm collection, probably not identical with Menge's specimen according to Ulrich (1927). Specimen lost. (3) Geologisch-palaontologisches Institut der Universitat Konigsberg, four specimens (Keilbach 1939). After 1945 parts of this col lection came to the Institut fur Geologie und Palaontologie der Universitat Gottingen. There, in 1966, Kinzelbach found only an empty glass vial containing the label Mengea tertiaria.

(4) Private collection of G. Liedtke, Itzehoe, specimen no. KI 0983. Published in Kinzel bach (1978). (5) One specimen found in 1975 on the beach of the Baltic Sea near Gdansk, in Amber depart ment of the Museum of the Earth, Polish Academy of Sciences, cat. no. 9270. Descrip tion by Kulicka (1978), who designated it as the neotype of Mengea tertiaria. In a letter of 3 November 1978, Barbara Ceranowicz men tioned a total of four Strepsiptera in this col lection.

(6) One specimen in the amber collection of the Staatliches Museum fur Naturkunde in Stutt

gart, inv. no. BB-220-K, mentioned by Kin zelbach (1979).

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Kinzelbach & Pohl: The Fossil Strepsiptera

61

Fig. 1. Stichotrema sp. from Messel. (A) Host Camponotus sp. with two puparia. (B) Details.

Locality and stratum. Baltic amber, Eocene. Blue clay and coast of the Baltic Sea near Danzig/ Gdansk (Poland) and Konigsberg/Kaliningrad

bach 1972) (Fig. 2). For a definitive evaluation of Mengea tertiaria we need information about the female and about the host.

(Bussia).

Characteristics. Menge's original description is rather poor. Only Ulrich (1927) has given a complete description. Keilbach (1939) was the first to illustrate the straight, pointed aedeagus of the simple shape found in all plesiomorphic re cent taxa of Strepsiptera. The most outstanding characters of Mengea are also plesiomorphic: the presence of a free labium with labial palps, as shown by Menge (1866) and Ulrich (1927); the metacoxa is considerably less integrated into the metathorax than in all other known Strepsiptera and may even have been movable (Ulrich 1927; Kinzelbach 1971, 1978). On the other hand, the venation pattern of the hind wing does not differ in its essentials from that of recent Mengenillidae; the closed "cell" of the venation, depicted by all the earlier authors, is an artifact, caused by folds. This was first published by Kinzelbach (1978), based on specimen no. 4 in the Liedtke collection; it was confirmed by Kulicka (1978). Systematic Position. Pierce (1908) erected the monotypic family Mengeidae for Mengea tertia ria. Hofeneder (1910) united it with his Mengenillinae. The plesiomorphic structures of the taxon Mengeidae mentioned above suggest that it should continue to be ranked as a family, be cause it is probably not the ancestor but the sis ter-group of the recent Mengenillidae (Kinzel

Stichotrema weitschati Kinzelbach & Pohl, n. sp.

(Figs. 3, 4, 7G)

Diagnosis. A new species of the genus Sti chotrema from Baltic amber. The shape of the

postscutum and the cubital wing venation would formerly place this species in the Old World ge nus "Lychnocolax." Because this has proved to be an artificial concept (see Discussion), it is abandoned here. The hind wing is characterized by unique additional veins in the posterior part of the radial sector: R,

Rfi

Total length =1.6 mm (without appendages). Dark reddish brown like all Myrmecolacidae,

the degree of darkening depending on the thick ness or sclerotization of the cuticle.

Head, as typical for the Myrmecolacidae (cf. the median incision even in Lx), shortest along median line, dilating on both sides toward com pound eyes. Eyes composed of 31-33 rather well-spaced, reflecting ommatidia (Fig. 3). Antennae seven-segmented and third segment provided with a flabellum that reaches as far as tip of antenna. Fourth segment very short, with Hofeneder's organ (sensorial pit) hardly visible, followed by two short and one long terminal seg ments of the flagellum. Antennae as a whole ro-

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62

m

8 Family

Superfamlly

tMengeidae

Mengeoidea

Suborder

hosts

?

Pierce 1908

Pierce 1908

Thysanura

s

ij Mengenillidae

Mengenilloidea

Kinzelbach 1970

Hofeneder 1910

Mengenilliformia Kinzelbach 1971

Mengeniliidia w-5'

Kinzelbach 1969

o & fa'to

±T Corioxenidae Kinzelbach 1970

Corioxenoidea

Halictophagidae

Halictophagoidea

Perkins 1905

Perkins 1905

Callipharixenidae

Superfamilia

Pierce 1918

incerta

Bohartillidae Kinzelbach 1969

Bohartilloidea Kinzelbach 1969

fa

Corioxeniformia

s§

Elenchidae Perkins 1905

I o

ft i

Stylopifonnia

Stylopidia

Kinzelbach 1971

Kinzelbach 1969

Myrmecolacidae

Stylopoidea Kirby 1813

Saunders 1872

iH II™

|-»

Stylopidae Kirby 1813

Fig. 2.

ill

SSI

3-

Diagram of the main bifurcations of the Strepsiptera (modified from Kinzelbach [1990]).

bust and broad compared with the slender anten nae of other Myrmecolacidae. Most of the surface of flabellum and of segments 5—7 covered by sensilla basiconica (Fig. 4). Mandibles sclerotized. Maxillae composed of a short basal part (corpus maxillare), to which a long, slender, slightly curved palpus maxillaris consisting of one segment is connected in an anteroventral direction. Palpus covered with short microtrichia. The mouth region itself is in visible.

Prothorax and mesothorax short. Only general outlines can be discerned. Metathorax also has

the usual proportions and sclerites. Postscutum

rather short and cuneiform, as in most "Lynchnocolax." The legs also have no special charac ters. For the main proportions, see Fig. 3A, B. They terminate in four-segmented tarsi without claws.

The short, club-shaped forewings are seen in frontal view, without special characters. Hind wings are partly extended, which enables the very special wing venation to be reconstructed (Fig. 7G). As usual, the anterior edge of the wing consists of a sclerotized and pigmented area of costa and subcosta. These are followed by a com plete set of radial veins. Rx originates together with R4 and extends to margin of wing. R2 and R3

B Fig. 3. Stichotrema weitschati, n. sp., lateral view. (A) Photograph. (B) Drawing. Abbreviations: FW, forewing; MD, mandible; MX, maxilla.

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Type Material. HOLOTYPE: 1 6, in Baltic amber, Museum Hamburg, no. SGPIHM 3117. The specimen is well preserved, but because it

is lying on a surface coated by two different flows of resin ("Schlaube"), it is partly surrounded by an air bubble. Consequently, some essential parts are not clearly visible and the total recon struction of a normal view (dorsal, lateral) is im possible without advanced techniques. Locality and Stratum. Baltic amber, Eocene. Weitschat, curator at the Hamburg Museum, con firmed the presence of the stellate plant hairs ("Sternhaare") that are characteristic of Baltic amber.

Systematic Position. The most striking charac ter is the wing venation, which suggests that this species could be placed in its own genus after a revision of Stichotrema. The insect shows more

Fig. 4.

Stichotrema weitschati, n. sp., antenna.

veins than any other known species of Myrme colacidae; some veins, such as the additional sec tions of R3, are even new for the Strepsiptera. Unfortunately, there is considerable individual variation in the wing venation of the Strep siptera, so the importance of this observation made on a single individual should not be over blown for the present.

are broad and pigmented patches without any connection with other veins in the anterodistal

part of the wing, as in most Strepsiptera. R4 short and after a break is continued by R5 as far as the wing margin. In addition to this customary pat tern of the radius sector, there are some special features: the occurrence of relics of the begin nings of three more veins, R3a—R3c, which have not been found in other Strepsiptera; and a dark ened area, running parallel to R4 caudally for Va of width of wing. Its line is continued after a long break by a patchlike vein Re, which resembles usual R2—R3 patches in shape and size. Its iden tification as radius is not final, but there is no

other choice because MAX (see below) starts be fore the median plate; it cannot be identified as MP, even if the R6 region is interpreted as MA. Similar spots, found for example in Hylecthrus, have been interpreted as MAX. This may not be the last word on the subject. The radial sector is followed by the medial sector. This starts with a typical MA1? originating from the medial plate on wing base, ending halfway, and continued after a break by MA2 to wing margin. There are no signs of MP, except as an acute outgrowth on caudal end of medial plate. Both cubital veins present: CuA2 characteristically concave, followed by CuA2 and CuP. No anal veins, as always in Myrmecolacidae.

Dominican Amber

Myrmecolax glaesi Kinzelbach, 1983

Myrmecolax glaesi Kinzelbach, 1983, Verh. Naturwiss. Ver. Hambg. (nf) 26: 31-33, figs. 1-2.

Material Examined. Male imago in the collec tion of the Geologisch-Palaontologisches Institut der Universitat Hamburg, no. 1232. Locality and Stratum. Dominican amber, prob ably Oligocene. Characteristics. This species differs only in de tails from the recent nominal species known from the Neotropical Region: CuP of the hind wing is not present or is only very weakly devel oped; and flabellum of third antennal segment reaches as far as tip of antenna. There are three recent species of Myrmecolax in the Neotropical Region: M. borgmeieri Hofeneder, 1949 from Argentina; M. trinidadensis Giinther, 1949 from Trinidad; and M. incautus de Oliveira & Kogan, 1959 from Brazil. They differ only in details, mainly in the proportions of the antennal segments, which are subject to infraspecific variation. They probably belong to a single species.

Most of the abdomen is concealed beneath the

hind wings. The tenth abdominal segment, bear ing the aedeagus, is visible; aedeagus is curved as usual in Myrmecolacidae. Unfortunately, its tip is obscured by artifacts. Derivatio Nominis. Dr. W. Weitschat, Museum Hamburg.

Stichotrema beckeri de Oliveira & Kogan, 1959

Stichotrema beckeri de Oliveira & Kogan, 1959, Mem. Inst. Oswaldo Cruz Rio J. 57(2): 219233; Luna de Carvalho, 1978, Garcia de Orta Ser. Zool. 7(1-2): 41-106.


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Vol. 87, no. 1

Fig. 5. Stichotrema dominicanum, n. sp., lateral view. (A) Photograph. (B) Drawing. Abbreviations: PS, postscutum; IX, ninth abdominal segment.

Stichotrema trilohulata Brailowski, 1974, Bev. Soc. Mex. Hist. Nat. 35: 167-173.

Stichotrema aff. beckeri: Kinzelbach, 1983, Verh. Naturwiss. Ver. Hambg. (nf) 26: 33-34.

Material Examined. Only male imagines. Nos. 1—3 were described by Kinzelbach (1983). (1) Collection of G. Liedtke, Itzehoe. (2) Collection of J. Scheven, Hagen-Hohenlimburg. (3) Collection of J. Wunderlich, Straubenhardt. (4) One more specimen in the J. Scheven collec tion.

Locality and Stratum. Dominican amber, prob ably post-Oligocene. Characteristics. The specimens listed above differ among themselves in very few details (e.g., number of ommatidia [12—15 versus 20-22] and proportions of antennal segments). There is also no striking difference from the recent Sti chotrema beckeri. All observed variations are

considered to be caused by artifacts of preserva tion and description or a result of infraspecific variation.

Stichotrema dominicanum Kinzelbach & Pohl, n. sp.

(Figs. 5, 6, 7H) Diagnosis. A Stichotrema species, the first New World species to display the plesiomorphic pattern of cubital wing veins traditionally attrib

uted to "Lychnocolax." It differs from other spe cies mainly by one important character, the ab sence of MAj and MA2 in the hind wing. Total length —1.3 mm (without appendages). Dark reddish brown like all Myrmecolacidae, the degree of darkening depending on the de gree of sclerotization of the cuticle. Head shows characteristic shape of the Myrmecolacidae. Eyes composed of 13—16 om matidia, with little space separating them. Antennae seven-segmented, and third seg ment provided with a flabellum that reaches as far as base of last (seventh) segment of flagellum. Fourth segment very short, followed by one long and two short terminal segments of flagellum. Antenna as a whole robust and broad. Most of

surface of flabellum and of segments 5—7 covered by sensilla basiconica. Mandibles sclerotized and comparatively short; they and maxillae mainly covered with microtrichia. As usual in this family, mouth re gion consists of a sclerite (fused product of la bium, hypopharynx, and labrum) with a central mouth opening after the first V3. Prothorax and mesothorax short. Only general outlines recognizable. Metathorax also has the usual proportions and sclerites. Postscutum rather short, as in the genus "Lychnocolax" (Fig. 5A, B). Legs have no special characters; they are partly disarticulated. They end in four-seg mented tarsi without claws. The short, club-

shaped forewings are without special characters.

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segment (shared with Elencholax), and, most im portant, a long vein R5, a plesiomorphic charac ter shared with the Myrmecolacidae, the sistergroup of the Elenchidae (Kinzelbach 1979). Systematic Position. The most plesiomorphic representative of the Elenchidae.

Bohartilla joachimscheveni Kinzelbach & Pohl, n. sp.

(Figs. 8, 9, 10A)

Diagnosis. A fossil species of Bohartilla that in general is very similar to the only known living relative, B. megalognatha Kinzelbach, 1969 from Honduras. The species is generally more slender than B. megalognatha and antennae, maxillae, and legs are relatively longer. Total length «1.3 mm (without appendages). Brown, with whitish intersegmental and articu lation membranes.

Fig. 6. Stichotrema dominicanum, n. sp. (A) An tenna. (B) Aedeagus.

Left hind wing extended, enabling the wing ve nation to be reconstructed (Fig. 7H). Abdomen visible from the side. The tenth ab

dominal segment, with aedeagus, also visible. Aedeagus is curved as usual in Myrmecolacidae. Unfortunately, its tip is obscured by a wing membrane, so the drawing may not be fully ac curate (Fig. 6B). Type Material. HOLOTYPE: a fine 3 imago in a lateral normal position, in clear amber, collec tion of J. Scheven, Hagen-Hohenlimburg. Locality and Stratum. Dominican amber, Oligocene.

Systematic Position. This specimen combines plesiomorphic characters (e.g., the massive an tenna [cf. Stichotrema weitschati, n. sp.]) with apomorphic ones: smaller than average size, reduction of the media, elongated spina dorsalis of the aedeagus, and reduced number of ommatidia. The final position can only be deter mined after a more thorough revision of the genus.

Protelencholax schleei Kinzelbach, 1979

Protelencholax schleei Kinzelbach, 1979, Stuttg. Beitr. Naturkd. Ser. B (Geol. Palaeontol.) 52: 1-14.

Material Examined. One male in the amber collection of the Staatliches Museum fur

Naturkunde in Stuttgart, inv. no. Do-7-K-l. Locality and Stratum. Dominican amber, Oligocene.

Characteristics. This species is the most ple siomorphic representative of the Elenchidae, with a hook-shaped aedeagus (shared with Elencholax and Deinelenchus), free fourth antennal

Head in lateral view dominated by compound eyes, composed of 17—20 ommatidia with only a little space between them. Corneae not hemi spherical, as is usually the case, but roundedconical to some extent, probably an artifact. Antennae (Fig. 8) six-segmented; third, fourth, and fifth segments with a flattened flabellum. Surface of flabella and of segments 3-6 covered by sensilla basiconica. Mandibles sclerotized and comparatively short. Body of maxillae very long, which is char acteristic for this family, followed by one short, slender segment of maxillary palpus. Maxilla without the palpus equals in length coxa of prothorax. Proportions differ from those of B. megalognatha by presence of a longer palpus. Prothorax and mesothorax short. Only general outlines recognizable. In metathorax, postnotum shorter than in B. megalognatha: its length ex ceeds only slightly that of prescutum + scutellum. Legs also provide no specific characters; they seem to be somewhat more slender than in B. megalognatha, especially the four-segmented tarsi (Fig. 9A, B). The club-shaped forewings on the other hand seem to be more inflated. But these relative dif

ferences are hard to prove, because positions of mounted recent specimens and the fixed fossil are different and no direct comparison is possi ble. Hind wings are extended and cover each other almost exactly. Wing venation in general agrees with that of B. megalognatha (Fig. 10A, B); some minor differences reflect the individual variation well known in the Strepsiptera. Kinzel bach (1969) was suspicious about finding a relic, the pattern of a closed vein cell formed by MP and CuA. This is not visible in the fossil speci men; it was evidently a misinterpretation of the folds, as in Mengea tertiaria (see above). Entire abdomen visible from the side. Aedea

gus is withdrawn into ninth abdominal segment


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Vol. 87, no. 1

Fig. 7. Comparison of the venation pattern of the hind wing of some Myrmecolacidae, including the new

species: (A) Myrmecolax trinidadensis, (B) Myrmecolaxfurcatus,(C, D) Stichotrema retrorsum, (E) Caenocholax fenyesi, (F) Lychnocolax mindoro, (G) Stichotrema weitschati, n. sp. (H) Stichotrema dominicanum, n. sp. Abbreviations: Rr-R6, radius; MA!-MA2, media anterior; CUAJ-CUA2, cubitus anterior; CuP, cubitus posterior (A-E modified from Kinzelbach [1971]).

and only partly visible. It does not differ from that of B. megalognatha.

ture and description show two typical fea tures of Bohartilla: three flabellate antennal

segments and the wing venation. Type Material.

(1) HOLOTYPE. A very fine specimen in lateral view, collection of J. Scheven, Hagen-Hohenlimburg. (2) Published photograph of an undetermined specimen in the collection of Mr. Brodzinsky, Santo Domingo (Poinar 1982). The pic

Locality and Stratum. Dominican amber, Oligocene.

Systematic Position. As in most specimens

from Dominican amber, there are almost no dif ferences from living representatives at the spe cies level. Because only two specimens of the recent B. megalognatha have been reported so

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far, the extent of infraspecific variation is virtu ally unknown. So the fossil may represent only a geographic or host subspecies. Discussion

Fig. 8. tenna.

Bohartilla joachimscheveni,

sp..

The Fossils and the Systematic Position of Strepsiptera. The Strepsiptera are a well-defined taxon of entomophagous insects whose position in the natural system has not yet been defini tively resolved. Some entomologists have con sidered its particularity to be a result of early isolation and the subsequent development of nu merous autapomorphies. Others have argued in favor of a close relationship with the large orders of the Holometabola, above all with the subtaxa of the Coleoptera. The results obtained from this study of all the fossil Strepsiptera available at the current time have not resolved this long-standing problem of over two centuries, but they do lend support to the first-mentioned theory. Strepsiptera are thought to have diverged very early from the common ancestral line of all the Holometabola (Oligoneoptera) and to have sur vived in their parasitic niche as living fossils, comparable, for example, with the Cyclostomata among the Vertebrata. Morphologically they dis play a mosaic of plesiomorphic and highly spe cialized autapomorphic characters. The search

iTlWfr Fig. 9. Bohartilla joachimscheveni, n. sp., lateral view. (A) Photograph. (B) Drawing. Abbreviations: PS, postscutum; MX, maxilla.


68

CuA2

Fig. 10.

Vol. 87, no. 1

CuA0

Hind wing. (A) Bohartilla joachimscheveni, n. sp. (B) Bohartilla megalognatha.

for undoubted synapomorphies with other insect orders has to be continued. So far only the opisthomotoric flight mechanism (Ulrich 1943) and the structures related to it (Crowson 1938) suggest a tentative approach to the Coleoptera. They could easily be interpreted as parallelisms. The fossils known so far do not contribute di

rectly to the solution of this question, but indi rectly they provide strong support for the great phylogenetic age of the Strepsiptera. Comparing the fossil records with the dendro gram of the Strepsiptera based on structural ar guments (Fig. 2) shows that all taxa of the rank of family and genus already existed in the Eocene. This is shown by the direct evidence of the fos sils or indirectly: if more specialized taxa were already in existence, then all the preceding branchings must have taken place in much ear lier periods. This refers especially to the highly differentiated Myrmecolacidae, which accumu lated strongly autapomorphic characters (e.g., host dimorphism). The Myrmecolacidae and (partly) their sister-group the Elenchidae also share the character of secondary segmental brood organs in the females. Because these late and specialized taxa already existed in the Eocene, they suggest that the older branchings must go very far back, probably as far as the Permian (Kinzelbach 1971, 1979, 1990). The Fossils and Systematics within the Strep siptera. In some cases the fossils contribute to an understanding of evolution within the Strep siptera.

Mengeidae. Mengea tertiaria is most impor tant. This species gives some idea of the plesio morphic characters in Strepsiptera (e.g., free la bium and free metathoracic coxa). Others are

confirmed by the Mengenillidae and part of the Corioxenidae (e.g., straight aedeagus, seven an tennal segments, complete wing venation, the existence of free-living females). The Mengenil lidae are probably the recent sister-group of the Mengeidae. Myrmecolacidae. The generic subdivision of the Myrmecolacidae is not based on natural re lationships. The genus "Lychnocolax" in partic ular is not defined by autapomorphies. Bohart (1951) gave the completeness of the wing vena tion as the most striking character. Because the complete wing venation is a plesiomorphic char acter, which may or may not have been retained alongside further specialization, it cannot define a natural taxon. The second character given by Bohart is that the triangular scutellum in dorsal view is longer than the prescutum. Unfortu nately, this character has not been re-examined for all Myrmecolacidae and is not even known for all "Lychnocolax"; in the amber fossils it is hardly visible, because visual access is not pos sible from all directions.

In searching for synapomorphies, it was deter mined that "Lychnocolax" shows some internal inconsistencies concerning important characters (e.g., the absence or presence of the spina dorsalis of the aedeagus, the size of the hook of the aedeagus, the absence of some of the wing veins thought to be characteristic for the genus, occur rence of a short scutellum as in Stichotrema). So most of the apomorphic characters of the species attributed to this genus diverge very widely and converge with characters of Stichotrema and Myrmecolax. "Lychnocolax" is accordingly now abandoned as a natural genus, and all its species are provisionally transferred to Stichotrema.

January 1994


69

The traditional key to the genera of the Myrmecolacidae follows: 1. Hind wing with R2 and R3 2 1. Hind wing only with R2 or without R2 and R3 3 2. Only one media (MA), followed by 2 more veins (CuAx, CuP) (Fig. 7A, B) Myrmecolax 2. Two mediae (MA1? MA2), MAX frequently very short, followed by 3 more veins (CuA1? CuA2, CuP) (Fig. 7F)

sects, or they may have been attracted to this fluid by pheromonelike substances. Is it only by chance that neither the widespread Stylopidae and Halictophagidae nor the tropical Corioxenidae have been found in amber inclusions? The occurrence of Myrmecolacidae during the Eocene at several sites in central Europe, near to or far north of latitude 50°N, is further strong evidence of the tropical climate of Europe at that time, because the recent Myrmecolacidae are strictly confined to the tropics of the Old and

"Lychnocolax" 3. CuP long, aedeagus without spinae laterales (Fig. 7C, D, G, H) . . . . Stichotrema 3. CuP absent or inconspicuous, aedeagus with spinae laterales (Fig. 7E)

New World. The Messel and Geiseltal environments consisted of more or less tropical lowland forests. The presence of the Mengeidae also indicates that the climate during the Eocene of the contemporary Baltic region was warm but drier,

Caenocholax

because its sister-group Mengenillidae now lives

Of these genera, only Caenocholax is sharply

only in subtropical xerothermic regions of the

defined by an autapomorphic character, the pres-

Old World,

ence of spinae laterales on the aedeagus. Myrmecolax also has to be redefined. Promising characters are the apomorphic lack of MAX and the (always?) furcate R2. For the present, Stichotrema includes all the other Myrmeco-

So far as Dominican amber is concerned, it is no surprise to find Myrmecolacidae, Elenchidae, and Bohartillidae in a region where tropical climatic conditions have remained almost unchanged since the Oligocene. The species differ

lacidae. Revisional work and subdivisions still

little from their living representatives. This con-

pose a challenge. The new species S. weitschati, n. sp. and S. dominicanum, n. sp. described above have a full cubitus venation, which they share with "Lych-

firms that basic ecological conditions in MesoAmerica have remained stable for a long time, which facilitated the buildup of the tremendously rich biota that exist there now.

nocolax." In addition they also conform in the small hook of the aedeagus and the stout, flat

antennal segments and flabella. Both characters

Acknowledgments

are also plesiomorphic But S. dominicanum, n

For making their material avaiiable for study we

sp. is much further reduced by the absence of

cordially thank G. Liedtke (Itzehoe), H. Lutz

the peculiar veins of the radial sector and by the

(Naturhistorisches Museum Mainz), J. Scheven

absence of a media. Elenchidae. Within the Elenchidae, a compar-

(Hagen-Hohenlimburg), D. Schlee (Stuttgarter Bernsteinsammlung, Museum fur Naturkunde in Stuttgart),

ison of Protelencholax with the other known gen-

W. Weitschat (Hamburg), andJ. Wunderlich (Strauben-

morphic and thatElenchus is a very specialized

Pont (Goring-on-Thames).

era demonstrates that this genus is most plesio-

hardt)- For linguistic revision ofthe text we thank A. C.

genus, characterized by reductions (e.g., aedea

gus, fusion of antennal segments, loss of wing i

i

....

r

I'll

ir

Rpfprpnres Cited

l

iiciciciitcs \jiicu

veins, desclerotization ot mandibles and ot aede

agus). Either this may be an advanced character,

Bohart, R. M. 1951. The Myrmecolacidae of the

preceded by the apomorphic segmental argumentation, shared with Deinelenchus and all

Philippines (Strepsiptera). Wasmann J. Biol. 9(1): 83-103.

sinrnnrnhic in in this character when siomorpnic this character when comnared compared with all other Elenchidae and Myrmecolacidae.

chotrema Hofeneder, lacidae) para Mexico. 1910 Rev. (Strepsiptera: Soc. Mex. Hist.MyrmecoNat. 35: 167-173

The female has only one brood organ per seg-

Crowson, R. A. 1938. The metendosternite in Co-

ment. Strata, Facies, and Localities. Strepsipteran fossils stem from two sources: oil slate and am-

leoptera: a comparative study. Trans. R. Entomol. Soc. Lond. 87: 397-416. Grote, A. R. 1886. Changes Triaena Menge preoc-

Myrmecolacidae, or Elenchus may be most pie- Brailowski, H. 1974. Una^ nueva especie de Sti-

ber. This is easily explained as follows: (1) oil slate is more suitable than other sediments for

the preservation of the tiny relics ofthese para-

cupied, to Mengea n. nov. Can. Entomol. 18: 100. Giinther, V. 1949. Strepsiptera z Trinidadu B.W.I,

[Strepsiptera from Trinidad B.W.I.]. Acta Soc. En-

sites and so is amber; and (2) in oil slate either Hau^H ^

the findings are casual (e.g., Stichotrema eocae-

nicum) or the specimens are found on the host

aus der

eoz^nen Braunkohle des Geiseltales. Geologica 6: I-VII 1-168.

(e.g., Stichotremasp. from Messel); in amber the

Hofeneder, K. 1910. Mengenilla n. g. Dalla-Torrea-

Strepsiptera may have been caught accidentally by the sticky resin, as happened with most in-

num n. sp. Eine neue Strepsiptere aus Nordafrika. Ber. Naturwiss.-med. Ver. Innsb. 32: 33-58.

70


1949.

Uber einige Strepsipteren. Broteria 18: 109-

122, 145-166.

Keilbach, R.

1939.

Vol. 87, no. 1

Lutz, H. 1990. Systematische und palokologische Untersuchungen an Insekten aus dem Mittel-Eozan

Neue Funde des Strepsipterons

der Grube Messel bei Darmstadt. Cour. Forsch-

Mengea tertiaria Menge im baltischen Bernstein. Bernstein-Forschungen 4: 1-7. Kinzelbach, R. 1969. Bohartillidae, eine neue Fam-

ungsinst. Senckenb. 124: 1-165. Menge, A. 1866. Ueber ein Rhipidopteron und ein ige Helminthen im Bernstein. Schriftenr. Naturforsch. Ges. Danzig 2(1): 1-8. de Oliveira, S. J. & M. Kogan. 1959. A contribution to the knowledge of the Brazilian Strepsiptera (In secta). Mem. Inst. Oswaldo Cruz Rio J. 57(2): 219-

ilie der Facherfliigler (Insecta, Strepsiptera). Beitr. Neotrop. Fauna 6: 92-102.

1970. Loania canadensis n. gen. n. sp. und die Untergliederung der Callipharixenidae (Insecta: Strepsiptera). Senckenb. Biol. 51(1/2): 99-107. 1971. Morphologische Befunde an Facherfliiglern und ihre phylogenetische Bedeutung (Insecta, Strepsiptera). Zoologica (Stutt.) 41(119) 1. Halfte: XIII, 1-128; 2. Halfte: IV, 129-256. 1972. Die Facherfliigler des SenckenbergMuseums. II. Mengenillidae (Insecta: Strep siptera). Senckenb. Biol. 53(5/6): 403-409. 1978. Strepsiptera, pp. 1-166. In K. Senglaub & H.-J. Hannemann [eds.], Die Tierwelt Deutschlands 65 (begriindet von F. Dahl). VEB Gustav Fischer, Jena. 1979. Das erste neotropische Fossil der Facher fliigler (Stuttgarter Bernsteinsammlung: Insecta, Strepsiptera). Stuttg. Beitr. Naturkd. Ser. B (Geol. Palaeontol.) 52: 1-14. 1983. Facherfliigler aus dem dominikanischen Bernstein (Insecta: Strepsiptera: Myrmecolacidae). Verh. Naturwiss. Ver. Hambg. (nf) 26: 29-36. 1990. The systematic position of Strepsiptera (In secta). Am. Entomol. 36(4): 292-303. Kinzelbach, R. & H. Lutz. 1985. A stylopid larva from the eocene: a spotlight on the phylogeny of the stylopids (Insecta: Strepsiptera). Ann. Entomol. Soc. Am. 78: 600-602.

Kirby, W. 1813. VI. Strepsiptera, a new order of in sects proposed; and the characters of the order, with those of its genera, laid down. Trans. Linn. Soc. Lond. 11: 86-123.

Kristensen, N. P.

1981.

1905.

The leaf-hopper of sugar

cane. Bull. Div. Entomol. Haw. 1.

Pierce, W. D. 1908. A preliminary review of the classification of the order Strepsiptera. Proc. Ento mol. Soc. Wash. 9: 75-85.

1918. The comparative morphology of the order Strepsiptera together with records and descriptions of insects. Proc. U.S. Nat. Mus. 54: 391-501, pi. 64-78.

1964. The Strepsiptera are a true order, unrelated to Coleoptera. Ann. Entomol. Soc. Am. 57: 603-605. Poinar, G. O. 1982. Feature photograph (Strep siptera). Ann. Entomol. Soc. Am. 75(6): 586. Rossius, P. 1793. Observation de M. Rossi sur un nouveau genre d'Insecte, voisin des Ichneumons. Bull. Soc. Philomatique 1: 49. Saunders, S. S. 1872. Stylopidarum, ordinem Strepsipterorum Kirbii constituentium, mihi tamen potius Coleopterorum Familiae, Rhipiphoridis Meloidisque propinquae, Monographia. Trans. R. Entomol. Soc. Lond. 1872: 1-48.

Ulrich, W. 1927. Uber das bisher einzige Strepsipteron aus dem baltischen Bernstein und iiber eine Theorie der Mengeinenbiologie. Z. Morphol. Oekol. Tiere 8(1/2): 45-62. 1943. Die Mengeiden (Mengenillini) und die Phylogenie der Strepsiptera. Z. Parasitenkd. 3: 62-101. Voigt, E. 1938. Weichteile an fossilen Insekten aus der eozanen Braunkohle des Geiseltales bei Halle/

Phylogeny of insect orders.

Annu. Rev. Entomol. 26: 135-157. *

Kulicka, R. 1978. Mengea tertiaria (Menge), (Strep siptera) from the Baltic ambers Pr. Mus. Ziemi Warsz. 29: 141-145, pi. I, II. Luna de Carvalho, E. 1978. African Strepsiptera (Ethiopian region). Garcia de Orta Ser. Zool. 7(1-2): 41-106.

233.

Perkins, R.C.L.

Saale. Nova Acta Leopold, (nf) 6(34): 1-38. Westwood, J. O. 1861. Notice on the occurence of a strepsipterous insect parasitic in ants discovered in Ceylon by Herr Nietner. Trans. Entomol. Soc. Lond. (2a)5: 418-420, tab. 1, figs. 1-13; (3a)l: 23.

Received for publication 19 November 1992; ac cepted 26 July 1993.