Myrmica longispinosa

†Myrmica longispinosa; Temporal range: Bartonian, Middle to Late Eocene K Pa Eo Ol Mi Pl Baltic amber, Baltic Sea region
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Myrmicini
Genus:	Myrmica
Species group:	ritae
Species:	†M. longispinosa
Binomial name
	†Myrmica longispinosa; Mayr, 1868

Photo Gallery

Radchenko (2023), Figure 1. Myrmica paradoxa, workers: (A) holotype and paratype, general view (arrows indicate propodeal teeth); (B) holotype, head and antenna (arrows indicate shape of frontal carina and 3-segmented funicular club); Myrmica longispinosa, worker, neotype: (C) body, right side lateral view; (D) body, left side dorso-lateral view; (E) hind tibia. Scale bars: A–D – 1 mm, E – 0.5 mm.

Identification

Radchenko (2023) - Meso- and metatibiae with conspicuous pectinate spurs; head, mesosoma and waist coarsely sculptured; upper lateroventral corners of head somewhat pointed; eyes located approximately at midlength of sides of head; scape gradually, but quite strongly curved at base, without any angle, lobe or carina (similar to modern Myrmica sulcinodis); mesosoma long and low; petiole long and low; propodeal spines directed mainly backward (seen in profile) and very slightly divergent (seen from above).

Myrmica longispinosa differs from Myrmica dictyosa by the presence of pectinate spurs on the meso-and metatibiae and by the longitudinally rugosed mesopleura, propodeum and waist (vs. completely coarsely reticulated mesosoma in the latter). It is distinguished from Myrmica electrina and Myrmica saxonica by the long and slender mesosoma (ML/MH > 3.5) and long and low petiole (PL/PH > 1.50) vs. shorter and more robust mesosoma and short and high petiole in the latter species (ML/MH ≤ 2.50, PL/PH < 1.30). In general appearance, Myrmica longispinosa resembles Myrmica eocenica, Myrmica rudis, Myrmica intermedia and Myrmica damzeni, but differs from all of them (except M. eocenica) by the presence of pectinate spurs on the meso- and metatibiae. It differs from M. eocenica in having very weakly diverging propodeal spines (vs. strongly divergent ones) and a gradually but rather strongly curved scape at the base (vs. the very weakly curved scape in the latter species). In M. rudis and M. intermedia, the eyes are located in front of the midlength of the sides of the head, while in M. longispinosa they are located approximately at the midlength of the sides of the head; moreover, the propodeal spines of M. rudis are directed more upwards and distinctly divergent. From M. damzeni it is well distinguished by a much more abundant erect or suberect pilosity on the body and appendages, vs. very sparse scattered thin suberect hairs on the body and very sparse thin decumbent hairs on the appendages.

Wheeler (1915) studied the Mayr’s holotype specimen and an unnumbered additional worker from the Königsberg’s collection, but added very little to Mayr’s description.

According to Mayr’s description, the most important diagnostic features of this species are the following:

meso- and metatibiae with distinct pectinate spurs
head and mesosoma with very coarse sculpture
antennal scape strongly, but gradually curved at the base
propodeal spines long, directed mostly backward and slightly divergent (seen from above)

Unfortunately, Mayr’s drawing of this species is too schematic to be helpful (Mayr 1868, Fig. 86).

The neotype specimen of M. longispinosa designated by Rachenko (2023) corresponds well to the original description with one exception: Mayr noted that the propodeal lobes of the holotype specimen are not pointed apically, while they are pointed in the neotype. Since the most of the holotype specimen was covered with a white film, the shape of the propodeal lobes was probably not clearly visible (see also Mayr 1868; Wheeler 1915).

Keys including this Species

Distribution

This taxon was described from Baltic amber, Baltic Sea region, Europe (Bartonian, Middle to Late Eocene).

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

†longispinosa. †Myrmica longispinosa Mayr, 1868c: 87, pl. 4, fig. 86 (w.) BALTIC AMBER (Eocene). See also: Radchenko, Dlussky & Elmes, 2007: 1495; Radchenko & Elmes, 2010: 654.

Type Material

Neotype worker (designated by Radchenko, 2023), complete specimen, Baltic amber, No. JDC 8606 (SIZK); worker, complete specimen, Baltic amber, No. JDC 6810 (CJDL).

Type locality: Poland, Baltic amber, late Eocene, Priabonian age, 37.8–33.9 Ma.

Description

References