Tarsophlebia eximia ( Hagen, 1862 )

Fleck, Günther, Bechly, Günter, Martínez-Delclòs, Xavier, Jarzembowski, Edmund A. & Nel, André, 2004, A revision of the Upper Jurassic-Lower Cretaceous dragonfly family Tarsophlebiidae, with a discussion on the phylogenetic positions of the Tarsophlebiidae and Sieblosiidae (Insecta, Odonatoptera, Panodonata), Geodiversitas 26 (1), pp. 33-60 : 36-39

Tarsophlebia eximia ( Hagen, 1862) ( Figs 1 ; 2 )

Heterophlebia eximia Hagen, 1862: 102 , 106.

Euphaea longiventris Hagen, 1862: 106 , 121, pl. 13, figs 7, 8.

Tarsophlebia eximia – Hagen 1866: 65, pl. 2, figs 1-6, 11.

Agrion latreillei [sensu Meunier] Meunier, 1896: pl. 1. Agrion exhaustum [sensu Meunier] Meunier, 1896: pl. 2. Tarsophlebia major Handlirsch, 1906: 580 .

? Tarsophlebia longissima Handlirsch, 1906: 581 .

Tarsophlebiopsis mayi Tillyard, 1923: 149 (n. syn.).

HOLOTYPE OF HETEROPHLEBIA EXIMIA . — Specimen No. AS-VI-44a-b ( BSPGM). The holotype of T. major is in the collection of the National Museum in Prague ( Malz & Schröder 1979: 26). Tarsophlebiopsis mayi is known by the holotype specimen, only represented by three wing fragments, located in the collection of Sedgwick Museum, Cambridge, UK.

GEOLOGICAL SETTING. — Upper Jurassic (“Oberer Weissjura”, Malm ξ 2b), lower Tithonian, Hybonotum-Zone, Solnhofen Formation (Solnhofen Lithographic Limestone), Eichstätt area, near Solnhofen, southern Frankonian Alb, Bavaria, SW Germany. The type specimen of T. mayi was found at the Boulder Clay (probably derived from the Ampthill Clay, Corallian), Hertfordshire, UK ( Tillyard 1923: 146).

DIAGNOSIS. — That of the genus. The fore wing length varies from 35-41 mm, and the hind wing length from 30-39 mm. The wing lengths of Tarsophlebia major Handlirsch, 1906 (39 mm) and Tarsophlebia longissima Handlirsch, 1906 (42 mm) still fit in this continuous

A range of variability. Since there are no other diagnostic characters known, we tentatively concur with the synonymization of Nel et al. (1993), even though the unusually large range of size would well allow the recognition of a distinct larger species of Tarsophlebia .

REDESCRIPTION

Head

A well preserved head is only known from specimen No. 6129 in coll. Carpenter of MCZ, which is labelled “ Tarsophlebia eximia Hag. - mas. - Counterpart - Solenhofen - Dr. Krantz” and indicated as “Type”. Hagen (1866) figured this specimen (reproduced by Nel et al. 1993: fig. 53a-b). Our re-examination of the specimen showed that the original figures were rather imprecise. We give a new figure, after the direct examination of the holotype ( Fig. 1C ).

Thorax

Nel et al. (1993: 85) remarked that all specimens with the synthorax preserved are in dorsal aspect, so that it is not possible to quantify exactly the degree of skewness (“prognathisme” sensu Nel et al. 1993) of the thorax. However, they estimate that the skewness was probably more important than in recent Zygoptera, Lestidae Calvert, 1901 . The very elongated humeral region (mesepisternum) of the synthorax with a very long dorsal carina (visible in specimens No. SOS 1705/ 1720 in JME) strongly supports a hypertrophied skewness.

Legs

The very long legs and tarsi stipulated the generic name Tarsophlebia . Legs of similar relative length are only known from the fossil protomyrmeleontid Malmomyrmeleon viohli Martínez-Delclòs & Nel, 1996 from the same locality (Martínez- Delclòs & Nel 1996). Hagen (1866) described a four-segmented tarsus, which was accepted by all subsequent authors, except Nel et al. (1993) who rejected this interpretation, since the type specimen is not sufficiently preserved. In fact, the tarsi of most specimens are far too poorly preserved to recognize the true number of tarsomeres. It is extremely hard to identify the different tarsomeres of the legs of these fossils. As example, only three tarsomeres could be identified on all tarsi of the specimen No. 1951/73K (JME) (Nel et al. 1993: 86), with the following putative lengths: the foreleg length of first tarsomere 3.0 mm, length of second tarsomere 1.5 mm, length of third tarsomere 2.0 mm; median leg length of first tarsomere 2.5 mm, length of second tarsomere 1.2 mm, length of third tarsomere 1.0 mm; hind leg length of first tarsomere 3.0 mm, length of second tarsomere 2.0 mm, length of third tarsomere 1.0 mm. Nevertheless, we found two well preserved specimens which clearly confirm the original description of four-segmented tarsi because they show four segment borders and the segments are angled and not aligned with each other. The right hind leg of the holotype specimen AS-VI-44b in BSPGM indeed shows four tarsomeres, with the following dimensions: length of first tarsomere 1.46 mm, length of second tarsomere 1.40 mm (both could correspond to the putative first tarsomere of specimen No. 1951/73K), length of third tarsomere 1.45 mm, length of fourth tarsomere 1.68 mm. The left foreleg of specimen No. 1960/ 66K in JME also shows four tarsomeres of more or less equal length.

The tarsi of all specimens show a pair of elongate tarsal claws that do not seem to have a subapical tooth (putative plesiomorphy, even though a reduction or artifact of preservation cannot be excluded).

Wings

They are extensively described in Nel et al. (1993), except for the following emendations: primary antenodal braces stronger than the secondaries; presence of a relatively long not zigzagged secondary vein (“postero-CuA vein”) closely parallel to distal part of CuA, in cubito-anal area and another one in area between MP and CuA (“antero-CuA vein”); presence of a relatively long not zigzagged secondary vein (“postero-MA vein”) closely parallel to distal part of MA, in postdiscoidal area and another one in area between RP3/4 and MA (“antero-MA vein”).

Abdomen

Several specimens (e.g., specimen No. SOS 1720 in JME) show the presence of a longitudinal mediodorsal carina on the abdominal terga, which is covered with a row of small spines. Specimen No. SOS 1720 also shows numerous tiny spines on the lateral parts of the abdominal terga, very similar to extant odonates (e.g., Calopteryx Leach, 1815 ).

Male secondary genital apparatus

There is a single male specimen (No. SOS 1720 in JME) that shows the male secondary genital apparatus, even though the specimen is preserved in dorsal aspect, since the ventral side is pressed through. Nel et al. (1993: fig. 54) figured this specimen, but the genitals were apparently difficult to interpret. The alleged male “auricles” of Tarsophlebia eximia , described by Nel et al. (1993: fig. 68) from the second abdominal segment of specimen No. 1650/57a-b in JME, are obviously based on a misinterpretation of the hamuli posteriors ( Bechly 1996; Rehn 2003: 201). We propose a new interpretation of the male secondary genital apparatus (see Fig. 1A ).

Female ovipositor

The female ovipositors are very long, extending well beyond the abdomen. They were already figured and described in Nel et al. (1993), on the basis of specimen No. SOS 3609, in JME. Fleck & Nel (2003) noted that, despite the fact they both have long ovipositor, its structure is different in the extant family Cordulegastridae Hagen, 1875 and the Mesozoic Aeschnidiidae Needham, 1903 . In the latter group, the valvula 1 is distinctly longer, narrower and weaker than in Cordulegastridae . The exact structure of the ovipositor cannot be established in Tarsophlebia because of the poor state of preservation of the available material.

Male anal appendages

The presence of a long ovipositor in female specimen supports the hypothesis that the specimens without such a structure are male. The anal appendages were always interpreted as calopterygoid-like, thus consisting of two pairs of long and curved claspers (cerci and paraprocts). Also, Nel et al. (1993: fig. 52) described such appendages from the holotype specimen. The discovery of very curious anal appendages of Turanophlebia vitimensis n. sp. (see below) stipulated the thorough re-examination of these structures in T. eximia . Indeed we could identify appendages of the same type in specimen No. 6222 in coll. Carpenter of MCZ, which is also labelled “ Tarsophlebia eximia Hag. - mas. - Counterpart - Solenhofen - Dr. Krantz” and indicated as “Type”. The previous misinterpretations are based on artifacts of preservation.

THE STATUS OF THE ENIGMATIC TARSOPHLEBIOPSIS MAYI TILLYARD, 1923

Tillyard (1923) described Tarsophlebiopsis mayi based on two wing fragments that were found in the body chamber of an ammonite from the Upper Jurassic of England. Fraser (1955) revised this specimen and provided a reconstruction of the complete wing. Nel et al. (1993: 92) considered that the holotype of this taxon could be just an aberrant specimen in the plesiomorphic character state “basal separation of the stems of M and Cu with several cross-veins between their stems”. We completely agree with this statement and now formally synonymize Tarsophlebiopsis mayi with Tarsophlebia eximia . The reasons are as follows: Nel et al. (1993: 92) falsified two of the four diagnostic characters mentioned in the original description of Tillyard (1923). Nel et al. (1993: 92) accepted the better-defined primary antenodal cross-veins Ax1 and Ax2 as valid diagnostic character. This state also occurs in Tarsophlebia eximia . Thus, except for two character states (“M and Cu basally separated”; “submedian space with two rows of cells”), all preserved characters (including size and fore wing venation) of Tarsophlebiopsis mayi are absolutely identical with Tarsophlebia eximia . Both taxa are from the Upper Jurassic of Middle Europe. The first mentioned difference is very strange, since this character state (“M and Cu basally separated”) would represent a unique plesiomorphy within Panodonata (= Tarsophlebiidae + Odonata ), which is only known from older and more basal stemgroup representatives of Odonata (e.g., Meganisoptera, Protanisoptera, Triadophlebiomorpha , and Protozygoptera ). All other tarsophlebiids agree with the derived character state of extant odonates. The second character state (“submedian space with two rows of cells”) is in the same area of the wing and could be related to the aberrant structure of veins M and Cu. Therefore, both character states of the holotype of Tarsophlebiopsis mayi could be related to an individual atavistic aberration (also known from other wing venational structures in extant Odonata ), or even as an artifact of preservation. The latter case could occur when the two membranes of the wing are separated and partly detached, which is for example a common phenomenon in amber damselflies.

Figures

FIG. 1. — Tarsophlebia eximia (Hagen, 1862); A, male specimen (SOS 1720, JME), secondary genital apparatus; B, male holotype (BSPGM AS-VI-44b), counterpart, right hind leg; C, male (No. 6129, coll. Carpenter, MCZ), head; D, male (No. 6222, coll. Carpenter, MCZ), male genital appendage. Scale bars: A, B, D, 5 mm; C, 10 mm.

FIG. 2. — Tarsophlebia minor n. sp., holotype (No. 55, coll. Carpenter, MCZ), left hind wing. Scale bar: 10 mm.