Ground-Living Spider

Females of Coelotes terrestris reach a body length of 10 to 13 mm, males 8 to 10 mm. The body structure corresponds to that of other species in the genus Coelotes. The prosoma (cephalothorax) of Coelotes terrestris, like other species in Coelotes and unlike other agelenids, is hardly narrowed. The carapace is dark red-brown to black. The sternum appears almost black. The legs are uniformly red-brown to dark red-brown. The opisthosoma (abdomen) has a dark gray to black-gray base color. Dorsally, there is also a dark median band in the anterior part of the opisthosoma, which narrows posteriorly and transitions into a yellow-gray chevron pattern in the posterior area. Posteriorly on the dorsal surface of the opisthosoma are yellowish-gray lateral stripes. Laterally, the opisthosoma has yellowish-gray patterns.

Genital morphology. In males of Coelotes terrestris, a single pedipalp, as typical for the genus Coelotes, has an apophysis (chitinized process) on the patella, whose distal edge is distinctly indented. The conductor (sperm duct) of a single bulb (male genital organ) has a narrow, short tip. The epigyne (external female genital organ) of the species is characterized within the genus particularly by the parallel lateral margins. The anterior margin is strongly pronounced. Between them is a square pit.

Differentiation from similar spiders. …

Coelotes terrestris is present in Europe and Turkey. The distribution extends north to Denmark. In Central Europe, the species is widespread except for the Baltic states and Kaliningrad Oblast as well as Croatia, which also applies to Western Europe. There, Coelotes terrestris is recorded in the Benelux countries, mainland France, and Great Britain. In Great Britain itself, the species is mainly present in southeastern England and replaces Coelotes atropos there. From other parts of Great Britain, there are only isolated records of Coelotes terrestris. Old records from Yorkshire and Berwickshire are likely based on confusions with Coelotes atropos, which, unlike Coelotes terrestris, mainly inhabits the west and north of Great Britain. In Eastern Europe, Coelotes terrestris is only present in Ukraine and Belarus, while in Southeast Europe, it has been recorded so far in Romania, Bulgaria, and North Macedonia as well as mainland Greece and the European part of Turkey. In Germany, the species particularly inhabits mountainous regions. Examples include the Franconian Jura, the Burgberg near Erlangen, and the area of the district Rathsberg near Erlangen.

Habitats. Coelotes terrestris preferably inhabits forests, that are not too dry. Among these, especially deciduous and coniferous forests with higher site quality are sought. …

Coelotes terrestris lives predatorily like all spiders and constructs a spider web for hunting purposes. Like all spiders with this hunting method, this species is also considered an ambush predator.

Web construction. The web of Coelotes terrestris is basically a funnel web typical and named for Agelenidae. Depending on the nature of the web site, it can be built very differently in this species. The spider works on its web only at night, corresponding to its activity period.

= Web location =. A common web site for Coelotes terrestris are trunks of pines (Pinus), and on a single pine trunk, several inhabited webs of the spider can be present even with a relatively small diameter of the trunk. Individuals living on these trunks preferably place their webs between the bark and the surrounding raw humus or litter layer. Occasionally, the spider uses surfaces under stones or tree stumps as web sites. To prevent flooding of the web when built at trunks by runoff water, Coelotes terrestris preferably places its web on the east side, but not the eastern half. Similarly, the species increasingly avoids the west and northwest sides of the trunks for the same reason. In addition, though less so, the north and south sides of the trunks are accepted, but intermediate directions are mostly avoided. …