CLASSIFICATION OF CENTIPEDES
Class Chilopoda - This class comprises five orders distinguished by the number of legs and pedal (leg-bearing) segments, and by the degree of "heteronomy" (unequalness) or fusion in the "tergites" (the dorsal segmental plates). The orders are combined into two subclasses based on the position of the "spiracles" (openings to the tracheal or respiratory system) and the general body form.

Subclass Notostigmophora - "spriacles" are located middorsally, head is "dome shaped."

Order Scutigeromorpha (1 family) - adults with 15 pairs of legs and pedal segments; hatchlings with four; characterized by very long legs and antennae, and fusion of tergites, resulting in less than 15 dorsal plates. Occurrence: worldwide except in North America where one species has been introduced and is commonly found in drains, sinks, bathtubs, and cellars in houses.

Figure 2. Scutigera coleoprata L. from Hungary, last legs missing. Photo by Z. Korsos.

Subclass Pleurostigmophora - "spiracles" located laterally, head flattened. Forms exhibit two modes of development - "anamorphic," in which hatchlings possess less than the adult complement of legs and segments, adding legs and segments, and becoming larger, at each molt; and "epimorphic," in which hatchlings possess the full adult complement of legs and segments, and become larger at each molt.

Order Lithobiomorpha (2 families) - "anamorphic" forms; adults with 15 pairs of legs and pedal segments; hatchlings with 6-8; exhibits strong tergite"heteronomy" with alternating long and short plates. Occurrence: Worldwide.

Figure 3. A common lithobiomorph centipede in the southern Appalachian Mountains. Photo by H. Ellis.

Order Craterostigmomorpha (1 family; also only 1 genus and at most 2 species) - "anamorphic" forms, adults with 15 pairs of legs and pedal segments, hatchlings with 12. Occurrence: Tasmania and the South Island of New Zealand.

Figure 4. (right) Craterostigmus tasmanianus Pocock from Tasmania. Photo by Z. Korsos.

Order Scolopendromorpha (3 families) - "epimorphic" forms with 21 or 23 pairs of legs and pedal segments, with a low degree of tergite "heteronomy" [segments are more-or-less uniform]. Includes the largest centipedes - the aggressive, intimidating species known to the general public. Occurrence: Worldwide.

Figure 5. (left) Scolopocryptops sexspinosus (Say), a common centipede in the forests of North America east of the Central Plains. Photo by H. Ellis.

Order Geophilomorpha (11-12 families) - "epimorphic" forms with 29 or more pairs of legs and pedal segments, without tergite "heteronomy." Includes the only centipedes with 100 or more feet/legs. Occurrence: Worldwide.

Figure 6. (right) Necrophloephagus longicornis (Leach) from Denmark. Photo by Z. Korsos.