A New Damothus and a Key to the North American Dignathodontid Genera (Chilopoda: Geophilomorpha: Dignathodontidae)

The genus Damothus was proposed by R. V. Chamberlin in 196o (p. 239) .for the reception of a single species, montis, which had been collected in the Wasatch Mountains of Utah. While collecting arachnids and myriapods at Ophir in the Oquirrh Mountains of that State, Dr. H. W. Levi unwittingly uncovered the second-known specimen of the genus, which I judge to represent a new species, alastus, here described. I wish to express nay thanks to Dr. Levi for his kindness in placing this and much other valuable material in my hands .for study. On the basis o.f all available information, the two most distinctive features of the genus are the massively crassate and essentially tubular ultimate legs of the male, and the presence o.f two basal denticles on the prehensorial tarsungula. Indeed, the latter character alone will distinguish Damothus from all other known chilopod genera of whatever order. After more is known about Damothus, it may well be seen that two other .features have significance diagnostically: the. peculiar shape o.f the St maxillary medial lobes; the relatively stronglydeveloped labral sidepieces. Comparing the Harvard specimen with Dr. Chamberlin’s original description o.f too.ntis, I find the .following to be significant distinguishing features. D. montis: (I) The first maxillae are without lappets. (2) The coxopleural pores are concentrated along and mostly concealed beneath the margins o"f the ultimate pedal sternite. (3) Ventral pore-fields are absent. D. alastus, n. sp.: (I) The first maxillary coxosternum bears a pair o"f conspicuous and relatively long lappets. (2) The coxopleural pores are all exposed and are not concentrated along and beneath the ultimate pedal sternite. (3) Small but conspicuous pore-fields are present on all pedal sternites except the last.