Paraphaenogaster freihauti

Identification
Jessen (2020) - This is the first fossil Paraphaenogaster, and there are not yet any known Oligocene Aphaenogaster workers. Two Aphaenogaster species, Aphaenogaster maculate and Aphaenogaster maculipes are gynes from the late Oligocene. Radchenko and Perkovsky (2016) informally allocated these species to the genus Paraphaenogaster. Since workers do not have wings, the main differentiating feature to allocate the genus is missing. So genus allocation is based on an assumption. For completeness and as a precaution, a comparision with all known Aphaenogaster workers is done herein. This species resembles Aphaenogaster sommerfeldti in its body contours. But sculpture of head differs. Head sculpture of A. sommerfeldti is described as fine wrinkled dots. Paraphaenogaster freihauti shows distinct longitudinal striae at head. It clearly differs from Aphaenogaster oligocenica and Aphaenogaster mersa because their promesonotum is not raised. In addition, head and alitrunk sculpture differs in A. mersa and Paraphaenogaster freihaut. Aphaenogaster amphioceanica is characterised by an elongated head and neck which are missing here. Aphaenogaster dlusskyana is bearing elongate-triangular mandibles and long spines in contrast to P. freihauti. Also Aphaenogaster praerelicta from Mexican amber shows long propodeal spines. In Aphaenogaster antiqua, propodeal spines are not widened at base, additionally, antennal segments 2–7 seem to be very short compared to those in P. freihauti.

Distribution
This taxon was described from.

This species and other fossil ants were collected as part of yearly excavation campaigns between 1995 and 2013 conducted by the Directorate General for Cultural Heritage Rhineland-Palatinate, Directorate Archaeology, Department of Earth History.

Nomenclature

 * †. †Paraphaenogaster freihauti Jessen, 2020: 14, figs. 6a, b (w.) GERMANY.

Worker
Holotype BLw/ oG: 4.25, HL: 1.34, HW: 1.24, ED: 0.19, GeL: 0.60, ML: 0.63, MML: 0.32, AL: 1.7, AH: 0.98, HiTL: 1.55, PL: 0.54, PH: 0.37, PPL: 0.34, PPH: 0.34, HeH: 0.22, G1L: 1.28, GL: 1.89. Indices: CI 92.31, IED/HL: 14.29, IHL/AL: 78.52.

Position: Head, alitrunk from dorsolateral, petiole, postpetiole and gaster from lateral.

Colour: Head, alitrunk and first gastral segment dark brown to black, petiole and postpetiole, gastral segments 2–4, and legs medium brown.

BL about 6.14. Head longer than wide, with smoothly rounded occipital corners. Head sides are slightly convex. Strong gena. Eyes located behind mid length of head. Eyes diameter is about 14.3% of head length. Mandibles stout, sub-triangular, with 7–8 teeth. Teeth have approximately the same size. Antenna hardly preserved, only some funicular segments preserved. The anterior margin of clypeus is smooth. Head with distinct longitudinal striae. Alitrunk elongate, slender. Promesonotum dome-shaped, pronotum sculptured longitudinal rugose. Along the middle of the pronotum, there is a deep longitudinal groove, but it is not clear if this is a morphological or a taphonomical feature. Dorsal profile line of propodeum distinctly lower than arched promesonotum. Propodeal spines short, acute, triangular, widened at base. Petiole with distinct peduncle that gradually develops into a tapered rounded node. Although link between peduncle and propodeum is partly disarticulated and morphology gets unclear, a small projection at anteroventral part of peduncle is indicated. Postpetiole in profile with smoothly rounded node. Postpetioles node not as high as petioles node. Helcium articulates at more than half of posterior face of petiole. Gaster complete. First gastral segment far the longest of all gastral segments, reaches slightly more than half-length of gaster.

Type Material
Holotype: NHMM-PE1995/8758-LS, worker. Enspel Oilshale, Rhineland- Palatinate, Germany. Enspel Formation, Upper Oligocene, MP 28; (24.56–24.79 Ma, Mertz et al. 2007), layer S14.

Abbreviation of specimen numbers:NHMM= Naturhistorisches Museum Mainz; PE = Palaeontology Entomology; 2009 = found in 2009; 6281 = running inventory number of the year; LS = Landessammlung (State Collection). Information on the layer is given. They refer to the standard profile in Felder et al. (1998).

Currently stored in the Directorate General for Cultural Heritage Rhineland-Palatinate, Directorate Archaeology, Department Earth History, Mainz, Germany. In the long term, they will be deposited in the “Typothek” of the State Collection of Natural History Rhineland-Palatinate/Museum of Natural History Mainz, Mainz, Germany (NHMM).

Etymology
Honouring Bernd Freihaut, Darmstadt, a distinguished architect, who ran the project to develop the Fossil- Lagerstätte Enspel and an industrial heritage of basalt mining to the famous touristic site Stöffel-Park (Enspel, Westerwald Mountains, Germany)