Mecistocephalus

Mecistocephalus is the largest genus of centipedes in the family Mecistocephalidae, with about 140 species. This genus is among the most diverse and widespread of all the genera in the order Geophilomorpha. The British entomologist George Newport first proposed this genus in 1843 to contain a group of centipedes marked by an unusual elongation of the head.

Description
Centipedes in this genus range from 2 cm to 10 cm in length. The head, forcipular segment, and their appendages are often elongated, and the cephalic pleurites feature a pair of sclerotized teeth. Each of the first articles of the forcipules often features a pair of denticles. The first pair of legs are markedly reduced in size.

A phylogenetic analysis of the family Mecistocephalidae using morphological features places this genus in the subfamily Mecistocephalinae along with the genera Tygarrup, Krateraspis, and Takashimaia. The genera in this subfamily share a set of distinctive traits, including setae on the clypeus that are limited to a short transverse band. Diagnostic features also include a body that tapers toward the posterior end and a cephalic plate that is evidently longer than wide.

Centipedes in the genus Mecistocephalus usually have 45 to 51 pairs of legs, but some have more, up to as many as 101 leg pairs. Most species in this genus have 49 pairs of legs (e.g., M. punctifrons and M. pallidus), but other species have 51 pairs (e.g., M. sechellarum and M. lifuensis), 47 pairs (e.g., M. angusticeps and M. tahitiensis), or 45 pairs (e.g., M. nannocornis and M. spissus). Intraspecific variation in the number of leg-bearing segments within each sex has been recorded among the species with the greatest number of legs in this genus: M. diversisternus, which has 57 or 59 leg pairs, M. japonicus, which has 63 or 65 leg pairs, and M. microporus, which has odd numbers of leg pairs ranging from 93 to 101, the maximum number in the family Mecistocephalidae.

Distribution
Centipedes in this genus occur mainly in tropical and subtropical regions of south and east Asia, with some also found in temperate areas and in the Americas.

Species
There are about 140 valid species, including:


 * Mecistocephalus angusticeps (Ribaut,1914)
 * Mecistocephalus apator Chamberlin, 1920
 * Mecistocephalus brevisternalis Takakuwa, 1934
 * Mecistocephalus capillatus Takakuwa, 1935
 * Mecistocephalus castaneiceps Haase, 1887
 * Mecistocephalus ciliatus Takakuwa, 1942
 * Mecistocephalus collinus Verhoeff, 1937
 * Mecistocephalus consocius Chamberlin, 1944
 * Mecistocephalus erythroceps Chamberlin, 1920
 * Mecistocephalus furculigera (Verhoeff, 1925)
 * Mecistocephalus gigas Haase, 1887
 * Mecistocephalus glabridorsalis Attems, 1900
 * Mecistocephalus gracilis (Verhoeff, 1925)
 * Mecistocephalus hebrides (Chamberlin,1944)
 * Mecistocephalus heteropus Humbert, 1865
 * Mecistocephalus kabasanus (Chamberlin, 1920)
 * Mecistocephalus kurandanus Chamberlin, 1920
 * Mecistocephalus labasanus (Chamberlin, 1920)
 * Mecistocephalus lifuensis Pocock, 1899
 * Mecistocephalus magister Chamberlin, 1939
 * Mecistocephalus manokwarius Chamberlin, 1944
 * Mecistocephalus marcusensis Miyosi, 1953
 * Mecistocephalus mater (Verhoeff, 1925)
 * Mecistocephalus modestus (Silvestri,1919)
 * Mecistocephalus nagasaunus Chamberlin, 1920
 * Mecistocephalus nigriceps Chamberlin, 1920
 * Mecistocephalus ocanus Chamberlin, 1946
 * Mecistocephalus okabei Takakuwa, 1942
 * Mecistocephalus ongi Takakuwa, 1934
 * Mecistocephalus porosus Haase, 1887
 * Mecistocephalus pseustes (Chamberlin,1939)
 * Mecistocephalus punctifrons Newport, 1843
 * Mecistocephalus siaronus (Chamberlin, 1920)
 * Mecistocephalus simplex Chamberlin, 1920
 * Mecistocephalus somonus (Chamberlin, 1920)
 * Mecistocephalus spissus Wood, 1862
 * Mecistocephalus subgigas (Silvestri,1919)
 * Mecistocephalus subinsularis (Silvestri, 1919)
 * Mecistocephalus tahitiensis Wood, 1862
 * Mecistocephalus tsenapus Chamberlin, 1944
 * Mecistocephalus turucanus (Chamberlin, 1920)
 * Mecistocephalus uncifer ( Silvestri,1919)
 * Mecistocephalus waikaneus Chamberlin, 1953
 * Mecistocephalus waipaheenas (Chamberlin, 1953)
 * Mecistocephalus zygethus Chamberlin, 1939