28 November 2023

The genus Ceraticelus is found in the family Linyphiidae which includes sheetweb spiders (subfamily Linyphiinae) and the dwarf/money spiders (subfamily Erigoninae). These are dwarf spiders and some of the smallest spider species found in Minnesota. They spin minute sheet-like webs in low vegetation or amongst the leaf litter. Adults can be found year-round and are most likely to be collected via sweep net or from sifting leaf litter (Kaston, 1948).

Most members of the genus are small (<2.0mm); females are slightly larger than males (Crosby & Bishop, 1925). The carapace is often orange to red-orange while the ocular area is often darker (black). In some of the males the ocular area is irregularly shaped and bulbous. The abdomen is variable in color but most often pale orange to cream in color. A sclerotized plate called a scutum (think armored plate) is often present and positioned toward the anterior of the abdomen on the dorsal surface. Legs are often unmarked. Members of this genus are most often confused with spiders in other genera within Linyphiiidae (Styloctetor, Ceratinopsis, Ceratinella, etc.) as well as genera within Araneidae (Hypsosinga) and Theridiidae (Thymoites).

Ceraticelus is represented by nine species in Minnesota (at this time) and caution should be taken when identifying them to species. There are no common names assigned to them. Two species are widespread and have been found more frequently than the others.

1) C. emertoni is often swept from grasslands and prairies and is known from 18 Minnesota counties at the time of this post. The male abdomen is almost entirely covered by the scutum. Both sexes are dark around the eyes and females lack a scutum. Examples of a male and female can be found here: https://www.inaturalist.org/observations/168356080.

2) C. fissiceps is also known from 18 counties at the time of this post and is often swept from the herb layer in forested ecosystems. Both sexes are dark around the eyes and both sexes also have a scutum. The ocular region of the carapace on males is bilobed and bulbous. A female can be seen here: https://www.inaturalist.org/observations/122823785. A male can be seen here: https://www.inaturalist.org/observations/126373950.

The other species are only known from 1-2 counties:

C. atriceps is similar to C. fissiceps. The males of this species also have a bilobed ocular area. A male C. atriceps collected for me by a student had a gray abdomen with an orangish scutum and gray abdomens are typical based on web-based images. In contrast, every male C. fissiceps that I've encountered had cream to orange abdomen with a darker orange scutum. Female C. atriceps lack a scutum on the dorsal surface of the abdomen but this structure is present in C. fissiceps. The epigyna are very similar between these two species though. A male is pictured here: https://bugguide.net/node/view/1672632/bgimage.

C. bryantae has a carapace that is orange-yellow with a darker eye region (Kaston, 1948). A female can be seen here: https://linepig.fieldmuseum.org/multimedia/1678182.

C. laetabilis is poorly known and there are very few pictures on the web. This species seems to differ from many members of the genus in Minnesota in that the carapace is generally darker (brown to red-brown) and the ocular area is not noticeably darker. The abdomen is paler and males have a scutum (Crosby & Bishop, 1925). See a female here: https://www.inaturalist.org/observations/26583563.

C. laetus is apparently similar to C. laetabilis in that it has a brownish carapace. Males of this species also have a scutum (Crosby & Bishop 1925). No images of this species can be found on BugGuide or iNaturalist at this time, but an image can be seen here : https://linepig.fieldmuseum.org/multimedia/1761666.

C. minutus is smaller than the other species (1.2-1.3mm) per Crosby & Bishop, 1925. Its carapace is described as brown with black reticulations (Crosby & Bishop, 1925). Very little is known about this species but habitus images of male and female can be found here: https://linepig.fieldmuseum.org/subset/habitus/381457.

C. paschalis has a yellow-orange carapace with darker eye region; the scutum on males has dusky lateral edges (Crosby & Bishop, 1925). No images of this species can be found on BugGuide or iNaturalist at this time but images of a female can be found here: https://linepig.fieldmuseum.org/multimedia/1761773.

C. similis has a yellow-orange carapace with darker eye region; males have a scutum while females do not (Crosby & Bishop, 1925). A female can be seen here: https://www.inaturalist.org/observations/46422530. A male can be seen here: https://www.inaturalist.org/observations/173792058.

SOURCES:
Crosby, C. R. & Sherman C. Bishop. 1925. Studies in New York spiders: Genera: Ceratinella and Ceraticelus. New York State Museum Bulletin, 264:1-46.

Kaston, B. J. 1948. Spiders of Connecticut. Bulletin of the Connecticut State Geological and Natural History Survey 70: 1-874.