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Eldermyrmex oblongiceps
| †Eldermyrmex oblongiceps Temporal range: Bartonian, Middle to Late Eocene Baltic amber, Baltic Sea region | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | Dolichoderinae |
| Genus: | Eldermyrmex |
| Species: | †E. oblongiceps |
| Binomial name | |
| †Eldermyrmex oblongiceps (Wheeler, W.M., 1915) | |
Dlussky (1997) postulated that this species likely did not belong in Iridomyrmex and that it “... most probably should be placed into another genus ...” However, he did not erect a new genus for it as he only had Wheeler’s (1915) drawing available and did not feel this was sufficient to establish a new genus. It is clear that this species does not belong to Iridomyrmex, and is, in fact, so distinct that assignment to a separate, and new, genus seems straightforward. This genus, Eldermyrmex, was established by Shattuck (in Heterick & Shattuck, 2011).
Identification
Key to the species of the genus Eldermyrmex
Key based on Dubovikoff et al. (2019).
- Head long (CI 158), with subparallel sides and straight occipital margin. Basal surface of propodeum is more long than declivous (Pl. 1, figs. 1, 2). Petiole with small conical node inclined forward => Eldermyrmex oblongiceps
- Head shorter (CI 120), with convex sides and deeply concave occipital margin. Basal surface of propodeum distinctly shorter than declivous. Petiole with high vertical conical node (Pl. 1, figs. 5, 6) => Eldermyrmex exsectus
Distribution
This taxon was described from Baltic amber, Baltic Sea region, Europe (Bartonian, Middle to Late Eocene).
Biology
Castes
Nomenclature
The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.
- †oblongiceps. †Iridomyrmex oblongiceps Wheeler, W.M. 1915h: 93, fig. 45 (w.) BALTIC AMBER (Eocene). Provisionally retained in Iridomyrmex: Shattuck, 1992a: 16. Combination in †Ctenobethylus: Dlussky & Rasnitsyn, 2009: 1036; in †Eldermyrmex: Shattuck, in Heterick & Shattuck, 2011: 170.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Description
Worker
Dubovikoffa et al. (2019)- mm: HL 1.06, HW0.67, EL 0.2, SL 0.71, VL 0.53, WL 1.47, PEL 0.27, F3 1.02, GL 1.84, TL 4.63, CI 158, EI 30, SI 67.
Body length about 5 mm. Head is rectangular, with pronounced occipital angles and an almost straight occipital margin; its length is noticeably longer than width (CI 158). Eyes rounded, markedly shifted forward. Maximum diameter of eye is 5 times less than length of head. Length of cheek is approximately equal to the maximum diameter of eye. Ocelli are absent. Antennae robust, 12-segmented. Scapus reaches the occipital margin of head but is not issued for it. The first segment of flagellum is 1.5 times longer than next. Length of segments 3–10 slightly greater than thickness. Anterior margin of clypeus straight; lateral angles above the mandibles slightly raised. Mandibles are triangular, teeth are not visible. Last segments of maxillary palps are absent, but it can be assumed that they reached the middle of the distance from the mouth to the occipital foramen and were 6 segmented. Labial palpi short, 4-segmented. Mesosome is slender, narrower than head. Pronotum convex, without humeral tubercles and keels. Dorsal surface of the mesonotum is flattened. Seam between mesonotum and mesopleuron missing. Propodeum elongated, angular in profile. Its dorsal surface is slightly concave, its length longer than length of declivous surface. Declivous surface of propodeum with longitudinal impression. Lateral surfaces of the propodeum are separated from the dorsal and posterior by a rather sharp bend. Propodeal spiracles are located on bend between posterior (declivous) and lateral surfaces of the propodeum. Petiole with low tilted forward conical node. Length of petiole is greater than height. Legs relatively short, with markedly thickened hips. Last sternite with a longitudinal keel. Entire body weakly shining, with shagreen sculpture. Standing hairs are visible on the mandibles, clypeus and the last tergites and sternites of abdomen.
Type Material
Dubovikoffa et al. (2019)- Holotype. GU, no. B 5385 (BST05036), worker, Baltic amber, Late Eocene.
References
- Dlussky, G.M. 1997. Genera of ants from Baltic Amber. Paleontological Journal, 31(6), 616–627.
- Dlussky, G.M. & Rasnitsyn, A.P. 2009. Ants in the Upper Eocene amber of central and eastern Europe. Paleontological Journal 43: 1024-1042.
- Dubovikoff, D.A., Dlussky, G.M., Perkovsky, E.E., Abakumov, E.V. 2019. A new species of the genus Eldermyrmex Shattuck, 2011 (Hymenoptera, Formicidae) from Bitterfeld Amber (Late Eocene) with species key of the genus. Paleontological Journal 53, 994–997 (doi:10.1134/S0031030119100046).
- Heterick, B.E. & Shattuck, S.O. 2011. Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae). Zootaxa 2845: 1–174.
- Shattuck, S.O. 1992. Review of the dolichoderine ant genus Iridomyrmex Mayr with descriptions of three new genera (Hymenoptera: Formicidae). J. Aust. Entomol. Soc. 31: 13-18.
- Wheeler, W. M. 1915. The ants of the Baltic Amber. Schr. Phys.-Ökon. Ges. Königsb. 55: 1-142.