Key to US Scolopocryptops

Scolopocryptops is a genus of small- to mid-sized scolopendromorph centipedes found throughout much of the US and often observed quite frequently where present. This key is for the six species found in the US and Canada. Many other species exist elsewhere, especially in Central and South America, and are not covered here apart from the genus diagnosis.

Genus diagnosis: eyeless; 23 pairs of legs; ultimate legs straight, slender, and "unmodified" (not pincer-like or subdivided). The number of legs is the most useful feature in distinguishing the family Scolopocryptopidae from Scolopendridae and Cryptopidae, while the form of the last legs distinguishes this genus from others in the same family (none of which are common in the US). Note that legs can be partially hidden or missing entirely, so counting body segments after the head is often more accurate.

Scolopocryptops has a distinctly bifurcate distribution, with a large gap in the middle of the continent. The two sides are treated separately below.

Anatomical terms

• The dorsal surface of each body segment is known as a tergite. The first one behind the head is tergite 1, or T1.
• Dorsal paramedian sulci are parallel or subparallel grooves than run lengthwise on a tergite on either side of the midline. This photo shows complete sulci that extend the full length of the tergite. When incomplete they can appear more like notches, or can be nearly indiscernable.
• The ultimate legs (aka terminal or caudal legs) aren't used for walking and typically extend straight out behind the body, but they still count in the 23 total pairs. One or both are frequently missing.

Western species

1. Complete paramedian dorsal sulci beginning on tergites 2-3. Orange color. Southwest BC through CA to northern Baja, extension to southwest UT through southern NV and northwest AZ. => gracilis
   Incomplete paramedian dorsal sulci, extending no more than 1/3 total tergal length from posterior margin. Reddish orange or brown color. Southwest BC to southern CA along Pacific coast. => spinicaudus

Eastern species

1. Complete paramedian dorsal sulci beginning on tergites 3-7. => (2)
   Incomplete paramedian dorsal sulci, extending no more than 1/3 total tergal length from posterior margin. => (3)

2. Pale yellowish color. Moderately dense hair on 2nd antennomere. NYC to eastern KY and northwestern NC. => peregrinator
   Red to reddish orange color. Moderately dense hair on 2nd antennomere. Southern MI and WI south to northern TX. => rubiginosus

3. Red to orange color. Dense hair on 2nd antennomere. Entire eastern US: eastern NE south to TX and east to the Atlantic, south to FL, north to NY and southern tip of Ontario. => sexspinosus
   Brownish color. Sparse hair on 2nd antennomere. Central PA south to FL panhandle, east to the Atlantic, west to Mississippi river up to southern IL. => nigridius

References

• Shelley, Rowland (2002). A synopsis of the North American centipedes of the order Scolopendromorpha (Chilopoda). Virginia Museum of Natural History Memoir 5.

Posted on 22 February, 2023 04:57 by jfmantis