Ictinogomphus hassleri, Schädel, Mario & Lechner, Thomas S., 2017

Schädel, Mario & Lechner, Thomas S., 2017, Two new dragonflies (Odonata: Anisoptera) from the Miocene of Carinthia (Austria), Zootaxa 4243 (1), pp. 153-164 : 157-159

Ictinogomphus hassleri sp. nov.

Figures 1 & 2

Holotype. The holotype is stored in the private collection of Dr. Andreas Hassler. The deposition of the specimen is projected in the State Museum of Kärnten, Klagenfurt, Austria under collection number LMK-Pal-2016-5538 (Old working-title: SIH-14).

Diagnosis. This new fossil species is very similar to modern representatives of the genera Ictinogomphus and Sinictinogomphus Fraser, 1939 . It differs from other Lindeniinae genera in the shape of the triangulum and the position of the Tspl-origin. The unique compilation of character states may not separate the fossil from all members of Ictinogomphus and Sinictinogomphus , but the remoteness in time and geographical range strongly suggests that the described specimen is not conspecific in the sense of a biological species concept.

The Lindeniinae fossil described by Huang & Nel (2009) from the Miocene of China has a distinctly larger hind wing than our specimen and 3 to 4 rows of cells between the origin of the secondary branch of IR2 and RP´´instead of only two rows as in our specimen (which is probably due to the larger size). With a length of 40 mm, the hind wing is distinctly larger than the Chinese specimen.

Our specimen is very similar to the specimen described by Nel & Paicheler (1994) from the latest Oligocene sediments in Bes-Konak, Turkey. The Bes-Konak specimen differs only in the manifestation of intercalated veins and the oblique pterostigmal brace vein, based on the area of the fossil wings that is preserved in both specimens.

The Ictinogomphus specimen from Seifhennersdorf (Early Oligocene, Germany; Prokop & Fikacek 2007; Prokop et al. 2016) cannot be clearly differentiated from our herein-described specimen, because the Seifhennersdorf specimen is represented by a forewing in contrast to our specimen that is represented by a hind wing.

Description. An almost complete wing lacking only anal region and basalmost part of ACuf as well as area basal to discoidal triangle. Total length 32.5 mm and total width 11.1 mm. Preservation better towards wingtip than in more basal part.

Anterior wing margin from base to nodus (CA & CP & ScA´) with short spines; nodus 14.1 mm from wing base and 18.4 mm from tip (at 43% of the wing length); secondary antenodal crossveins at least in distal part of ans not aligned.

Pterostigma with parallel anterior and posterior margin; 5.7 mm in proximodistal dimension and maximum 0.9 mm in anteroposterior dimension; posterior margin of pterostigma broader than anterior margin; proximal margin orthogonal and distal margin oblique with an angle of 134° to posterior margin. Pterostigmal brace vein broad and pointing posterior at a right angle to RA +; Preradial and Interradial field both with one row of cells.

Distal part of antesubnodal space not free; at least one crossvein between RA and RP´ 2.4 mm proximal of subnodus; distance between RP´–RP´´furca and subnodus 4.8 mm. Interradial sector with distinct secondary branch 7.8 mm distal from RP´–RP´´furca; two intercalated veins between IR2 + and its secondary branch and between same secondary branch and RP´´-.

RP1 and RP2 parallel and with one row of cells in between just near to level of proximal margin of pterostigma; intercalated vein between RP1 and RP2 from mid-pterostigmal level to posterior wing margin dividing area between outer veins more or less centrally; numerous small cells anterior and posterior of this intercalated vein.

Distance between arculus and RP furca (origin of RP´& RP´´) 6.3 mm; premedial field with one row of cells and with more or less parallel boundaries except for the very posterodistal part; posterodistal part of premedial field with two rows of cells and broader than anteroproximal part.

At least five antefurcal crossveins between RP - and MA +.

Htc 3.9 mm long and 0.8 mm wide; anterior margin of htc (MA +) distinctly curved.

Discoidal triangle longitudinally stretched and divided by at least two secondary crossveins; basal side 1.5 mm long; costal side 3.2 mm; posterodistal side 3.6 mm; posterodistal side (ddv) almost straight with a slight kink at origin of the distinct Tspl. Two rows of cells in basal part of postdiscoidal space. Strong secondary branch of MA + 4.5 mm distal of distal angle of discoidal triangle.

Gaff (CuA from posterior angle of discoidal triangle to CuA’/CuA’’-branching) 0.6 mm long (not prolonged); CuA´+ with 2 distinct secondary branches.

Type locality and horizon. Claypit Schaßbach (46°47'53.32"N, 14°48'23.77"E), St. Andrä , Wolfsberg (district), Carinthia, Austria. Fine laminated mudstone of the lacustrine lower part of the Mühldorf Formation. Age late Early Miocene.

Etymology. The species name hassleri refers to the finder of the specimen and local specialist for the field site Dr. Andreas Hassler, St. Andrä, Wolfsberg, Austria.

Wingspan estimation. The wingspan for the whole animal is estimated as about 70 mm, taking into account that the forewing is a bit longer than the hind wing in recent Ictinogomphus species.

Sex determination. The sex determination is not possible lacking the basal part of the wing.

Phylogenetic affinities. Anisoptera Selys, 1854 : strong expansion of the cubito-anal field, presence of a discoidal triangle and a hypertriangle ( Bechly 2007).

Gomphidae Rambur, 1842 : posterodistal side of the triangulum with a slight angle; presence of a trigonal supplement; distinctly curved anterior side of hypertriangle ( Bechly 1996, 2003).

Lindeniinae Jacobson & Bianchi, 1905: IR2 and MA both with a distinct secondary branch; hind wing discoidal triangle elongated in distal direction; distal side of triangulum sigmoidal shaped with a slight kink at origin of Tspl; triangulum with more than two cells ( Bechly 2003).

According to the slight differences in wing morphology and the large distance between the two fossil sites it seems not very likely that Ictinogomphus hassleri is truly conspecific but is closely related to the undetermined Lindeniinae fossil from Turkey ( Nel & Paicheler 1994).

Although our specimen resembles modern species of both Ictinogomphus and Sinictinogomphus , we suggest Ictinogomphus as the most suitable genus name due to the older age of the name.

Figures

FIGURE 1. Photograph of the hind wing fragment of Ictinogomphus hassleri sp. nov., holotype LMK-Pal- 2016 - 5538.

FIGURE 2. Drawing of the hind wing fragment of Ictinogomphus hassleri sp. nov., holotype LMK-Pal- 2016 - 5538, with terminology of wing venation.