Xystodesmidae is a familyofmillipedes. Its members often have very small distributional areas, with many species only known from a single locality.[1] They are found across the northern hemisphere, with peak diversity in the Appalachian Mountains, where one-third of the 300 or so species occur.[2] They are particularly abundant in deciduous broadleaf forests in the Mediterranean Basin, Africa, Asia, Central and North America, and Russia.[2] Information on basic taxonomy is scant for this family; for example, it is estimated that the genus Nannaria contains over 200 species, but only 25 were described as of 2006.[2] By 2022, 78 species in Nannaria have been described.[3]
This family also includes the cave-dwelling genus Devillea, notable for having more than the 20 segments (counting the collum as the first segment and the telson as the last) usually found the Polydesmida.[5][6] For example, in the species D. tuberculata, adult females have 22 segments and adult males have 21, with a corresponding increase in the number of leg pairs (35 in adult females and 32 in adult males, excluding the gonopods).[7][5][8] Some species in this genus also exhibit variation in segment number within the same sex, for example, in D. subterranea, adult males can have as few as 19 segments or as many as 23.[5][8] The species D. doderoi has the maximum number of segments recorded in this family (29, including the telson).[5]
The family Xystodesmidae was named by O. F. Cook in 1895, upon the description of Xystodesmus martensii, (previously Polydesmus martensii). Xytodesmidae is placed in the suborder Chelodesmidea within the order Polydesmida (the "flat-backed" or "keeled millipedes"). Xystodemids are characterized by a relatively broad and compact body shape and one or more spines on the second leg-segments (prefemoral spines) in most species.[9]
The family is divided into three subfamilies: the Melaphinae with around 10 species, the Parafontariinae with a dozen species in a single genus, and the Xystodesminae, with many genera and species.[10]
Unidentified Xystodesmidae, either Apheloria montana (Bollman) or Cherokia georgiana (Bollman). Purchase Knob, Smokies National Park, Haywood County, North Carolina, USA.
The subfamily Xystodesminae is subdivided into ten tribes,[10][11] each ending in the suffix "-ini", although taxonomist Richard Hoffman stated in his 1999 checklist: "I am by no means satisfied that this is the definitive arrangement, nor that the tribal divisions of the Xystodesminae are entirely satisfactory either."[10]
^Brölemann, H.-W. (1902). "Myriapodes Cavericoles". Annales de la Société Entomologique de France (in French). 71: 448–460 – via Biodiversity Heritage Library.
Data related to Xystodesmidae at Wikispecies
Media related to Xystodesmidae at Wikimedia Commons
