Schismiscapus exstinctum

A fossil species known from Mexican amber. One hundred thirty-seven worker specimens are embedded in single piece of amber, golden in colour, with a translucent glossiness (Figure 1A). The head of one worker specimen is more prominent than the others, suggesting polymorphism. It seems that all of these workers were trapped in the resin while foraging. Two other ant specimens identified as Camponotus sp. and Pheidole sp. were trapped in the same amber piece. Also, two specimens of Diptera, leaf litter, flower stamens, soil and bubble impressions, partially hiding some ants.

Identification
Scapes long, surpassing vertex of head by about twice the length of the scape, base of scape flattened and notched; compound eyes positioned anteriorly on head; mandibles with 15 teeth and denticles; hypostomal bridge forming a U-shaped notch without any denticule; mesosoma long, narrow and sinuous, mesonotum with two longitudinal dorsolateral carinae forming two angled process at the junction of the anterior and posterior faces of the mesonotum, metathoracic spiracle protruding dorsolaterally but not surpassing the mesosoma profilein lateral view (more evident in dorsolateral view), metanotal groove wide and deep; propodeum with distinct anterior,  dorsal and declivitous faces, dorsal face with a shallow mesal depression, dorsal and declivitous faces of propodeum forming a 90-degree angle, legs long and slender; long post peduncle that joints with the gaster; all body cuticle devoid of any ornamentation.

Distribution
This taxon was described from.

Nomenclature

 * †. †Schismiscapus exstinctum Varela-Hernández et al., 2022: 2, figs. 1B-D, 2A-D, 3 (w.) MEXICO (Mexican amber, Miocene).

Type Material

 * Holotype CPAL.447, amber inclusion (Figure 1B), La Pimienta site: 17°09ʹ11”N, 92°46ʹ08”W, Simojovel, Chiapas, Mexico. Mazantic shale and Balumtum sandstone strata, Miocene (Riquelme et al. 2014).
 * Paratypes from CPAL.448/n.1 to CPAL.448/n.137, amber inclusions.

The type material is housed in the Colección de Paleontología mantened at the Laboratorio de Sistemática Molecular, Universidad Autónoma del Estado de Morelos (CPAL-UAEM), Mexico.