Pilonychiurus, Pomorski, Romuald J., 2007

Pomorski, Romuald J., 2007, Three new genera of Onychiuridae (Collembola), Zootaxa 1461, pp. 49-58 : 56

Pilonychiurus gen. n.

Type species: Onychiurus delhezi Stomp, 1983: 192

Diagnosis. Body white, cylindrical, without anal spines. Head orthognathic. All abdominal segments demarcated. Integument with fine and regular granulation, without areas of coarser granules. Dorsal side of body with multiple pseudocelli which mostly are located on posterior margins of the terga. Posterior cephalic pseudocelli present, located on the back side of the granulated head capsule. Parapseudocelli absent. Furca reduced to two poorly defined areas of fine granulation on the border between abdominal sterna III and IV. Antennal III sense organ consisting of 4 papillae and granulated sensory clubs. Postantennal organ with simple vesicles. Labial palps unmodified, of AC type. Head of maxilla short with unmodified lamellae and typical ungulus. Chaetotaxy oligochaetose, usually symmetrical, microsetae often asymmetric. Dorsal setae distinctly differentiated into very thin and relatively long macrosetae and mesosetae. Microsetae are short and apically pointed. Seta d0 present on head. Tibiotarsi with 11 distal setae.

Etymology. The genus name is derived from the Latin word “pilosus”––hairy.

Discussion. Onychiurus delhezi was described on the basis of three specimens. Two of them have been lost (Weiner & Stomp, personal communication) but the holotype is still in the collection of the Museum of Natural History in Geneva. It is preserved in alcohol and completely cleared. Some parts of the body are wrinkled or destroyed and it is impossible to observe the postantennal organ, antennal III sense organ and details of the ventral tube. However, those characters which are possible to examine clearly show that the species does not belong to any known genus. Even the tribal association remains uncertain. Simple vesicles in the postantennal organ suggest relationship with Protaphorurini, but the structure of the reduced furca and the presence of d0 seta on head point to Onychiurini. The exceptionally long and thin macrosetae and the abundance of pseudocelli are known only in one other cave dwelling species, Ongulonychiurus colpus Thibaud & Massoud, 1986 . This similarity, however, may just be a simple convergence related to a troglobiotic life style. In spite of the presence of simple vesicles in postantennal organ I provisionally classify the Pilonychiurus gen. nov. within Onychiurini. New material is necessary to verify the tribal position of the species.