Rathke’s woodlouse

(Trachelipus rathkii)

               
Conservation Status

IUCN Red List

not listed

Rathke’s woodlouse

 

NatureServe

NNA - Not applicable

Minnesota

not listed

Occurrence

Not uncommon in Minnesota

Flight/Season

 

Habitat

On rotting logs; under logs, stones, and boards; and in woodsheds and greenhouses.

Size

Total Length: 316 to 716 (5 to 10.5 mm)

Photo by Alfredo Colon
 
Identification

Rathke’s woodlouse is a non-native isopod. It is native to central Europe, was introduced into North America, and now occurs from Newfoundland south to Tennessee and west to South Dakota. It is not uncommon in Minnesota. It is found in places with at least some dampness, including on rotting logs; under logs, stones, and boards; and in woodsheds and greenhouses. It is mostly a scavenger, eating plant and animal organic matter, but sometimes also feeds on living plants.

Adults are 316 to 716 (5 to 10.5 mm) in length, a little more than two times longer than wide. The body is oval in outline. It is compressed along its upper and lower sides (dorsoventrally flattened). It is dark brown with wavy pale lines, giving it a mottled look. There is a blackish longitudinal stripe down the middle and a row of pale spots on each side near the lateral margin.

The head is about twice as wide as long. It has three lobes in front; a broadly rounded lobe in the center, and a longer, narrower, rounded lobe on each side. There are two small compound eyes, one on each side of the head, and no simple eyes. There are two pairs of antennae. The first pair are small and have just two segments. The second pair has five segments and a whip-like tip (flagellum) with two segments. The fourth antennal segment is twice as long as the third, and the fifth is one-and-a-half times as long as the fourth. The segments of the flagellum are of equal length.

The thorax has seven segments of slightly unequal length. There is a single leg-like appendage on each side of each segment. The upper exoskeletal plate (tergite) on each thoracic segment and the first five abdominal segments is curved outward at each lateral margin. The rear (posterior) angle on each side is produced rearward. On the first thoracic tergite, the front (anterior) angle on each side is also produced forward.

The abdomen six segments, all of which are distinct. The lateral portions of the first two abdominal tergites are concealed beneath the seventh thoracic tergite. The third, fourth, and fifth tergites have the rear corners of the lateral margins produced, continuing the oval outline of the body. The last segment, the sixth, is called the telson The telson is triangular. On each side of the telson there is an elongated appendage, called a uropod. The uropods project well beyond the end of the body. On the under (ventral) side of the abdomen there are 5 pairs of lungs appearing as white patches.

 
Similar
Species

 

 
Juvenile Food

 

 
Adult Food

Plant and animal organic matter

 
Life Cycle

 

 
Behavior

Unlike pill woodlice (Family Armadillidae), Rathke’s woodlouse cannot roll into a ball.

 
Distribution Distribution Map  

Sources: 24, 29, 30, 82.

 
Comments

 

 
Taxonomy

Class:

Malacostraca (malacostracans)

 

Superorder:

Peracarida

  Order:

Isopoda (Isopods)

 

Suborder:

Oniscidea (woodlice)

 

Infraorder:

Holoverticata

 

No Rank:

Orthogonopoda

 

No Rank:

Crinocheta

 

Family:

Trachelipodidae

 

Genus:

Trachelipus rathkii

 
Synonyms

Trachelipus rathkei

 
Common
Names

Rathke’s woodlouse

 

 

 

 

 

 

Glossary

Tergum; tergite

The upper (dorsal), hardened plate on a segment of the thorax or abdomen of an arthropod or myriapod. Plural: terga.

 

Uropod

On some crustaceans, a pair of appendages on the sixth and final abdominal segment. On lobsters and similar species, it forms part of the tail fan.

 

 

 

 

 

       
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Alfredo Colon
       
  Rathke’s woodlouse    
       
       
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Camera

     
Slideshows
   
  Family: Trachelipodidae
Bill Keim
 
  Family: Trachelipodidae  
 
About

Order: Isopoda
Suborder: Oniscidea
Infraorder: Holoverticata
Zoosection: Crinocheta
Family: Trachelipodidae

Trachelipus rathkii (Rathke's Woodlouse)

 
     

 

slideshow

       
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Other Videos
 
  Trachelipus rathkii, Time Lapse
Donovan C
 
   
 
About

Mar 24, 2020

I wanted to make a nice little video of my friends eating their dinner, so I started recording a time lapse and walked away. I came back in an hour or so to find that my phone had stopped recording long ago. Bummer.

   
       

 

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Alfredo Colon
8/23/2019

Location: Woodbury, MN

Rathke’s woodlouse


     
     
 
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Created: 11/9/2020

Last Updated:

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